Tumor microenvironment-driven microRNA dysregulation: Key interactions in colorectal cancer progression

Abstract

Colorectal cancer remains one of the leading causes of morbidity and mortality worldwide. Despite notable advances in early detection and therapeutic strategies, the molecular mechanisms underlying tumor survival, chemotherapy resistance, and metastasis are not yet fully understood. MicroRNAs (miRNAs) have emerged as pivotal regulators of cancer development, as they modulate gene expression and orchestrate key signaling pathways. However, the epigenetic mechanisms that control miRNA expression and their downstream gene targets remain largely unclear. In this review, we highlight the critical role of the colorectal cancer microenvironment in influencing miRNA expression and discuss how this regulation contributes to tumorigenesis. A better understanding of these processes may lead to the identification of novel therapeutic targets and strategies to prevent recurrence.

Key Words: Cancer progression; MicroRNAs; Colorectal cancer; Tumor microenvironment; Therapeutic response

Core Tip: MicroRNAs are crucial regulators of colorectal cancer progression, influencing tumor development, therapeutic response, and serving as potential biomarkers or therapeutic targets. Their expression is strongly shaped by the dynamic interaction between tumor cells and the tumor microenvironment. This comprehensive review summarizes the key microRNAs implicated in tumor progression and discusses the main therapeutic targets, highlighting current knowledge and strategies designed to modulate their expression and enhance treatment response.

INTRODUCTION

Colorectal cancer (CRC) is one of the most common and aggressive types of cancer, ranking third in incidence and second in mortality worldwide[1]. Fortunately, CRC is characterized by hallmarks related to cellular and molecular mechanisms throughout its development, progression, and metastasis. Although its complexity is still being unraveled, factors such as specific mutations, the diverse pool of cells contributing to tumor parenchyma formation, immune suppression, and paracrine protein communication indicate that our understanding remains limited. As with other major diseases, various therapeutic strategies have been developed, including surgery, radiotherapy, chemotherapy, and immunotherapy. However, due to the nature and progression of the disease, nearly 50% of cases remain incurable[2]. Therefore, novel alternatives, such as microRNAs (miRNAs or miRs) regulation, represent promising options to explore.

MiRNAs are short non-coding RNAs ranging from 18 to 25 nucleotides in length. Their structure enables them to interact with messenger RNAs at the 3’ untranslated region (UTR) region, blocking translation and thereby regulating gene expression[3]. Over the past decade, it has become evident that altered expression of several miR’s is strongly associated with the etiology and clinical outcomes of many human cancers, including CRC, highlighting their potential roles in carcinogenesis[4]. While many miR’s work at a local nuclear level, recent developments have determined that miR’s are carried outside the cell via exosomes, hence establishing important communication amongst effector-affected cells, i.e., tumor to adjacent cells, developing crosstalk, which is vital for establishing the tumor microenvironment (TME). Thus, understanding the roles of miR’s is essential for clarifying the mechanisms underlying TME regulation and development. In particular, this review focuses on literature from 2015 to 2025, examining miRNAs and their validated molecular targets, incorporating, where applicable, studies participating in CRC progression, using in vitro and/or in vivo models, as well as patient samples. Special attention is given to alterations in the TME and to molecular pathways driving CRC progression such as proliferation, angiogenesis, migration, and therapeutic response.

MIR’S BIOGENESIS AND GENE EXPRESSION, AND CANCER PATHWAYS

MiRNAs act as chemical messengers that mediate intercellular communication in cancer regulation by functioning either as tumor suppressors, blocking malignant transformation, or as oncogenes, promoting cell proliferation and invasion[5]. MiRNAs often exhibit altered expression patterns that contribute to the acquisition of cancer hallmarks. Over time, studies have shown that epigenetic modifications, such as hypermethylation or hypomethylation of promoter CpG islands and dysregulated histone acetylation, can suppress tumor-suppressive miRNAs or enhance oncogenic miRNAs[6]. These alterations promote cell proliferation, resistance to apoptosis, invasiveness, and angiogenesis[7]. Therefore, changes in miR expression profiles may provide valuable insights into disease stage, therapeutic response, and patient prognosis, representing promising therapeutic targets across diverse cancer types[8].

During miR biogenesis, alterations in processing steps can lead to dysregulation. Mutations in key components of the miRNA machinery, such as DGCR8, DROSHA, and DICER1, have been linked to cellular transformation and tumor progression. In addition, many miRs are located in genomic regions prone to deletion, amplification, or translocation in cancer[8]. Alterations in the 3’ UTR and other structural changes can affect RNA structure and binding sites, impairing pre-miR transcription and miR expression, which in turn dysregulate target genes. Some miRs, such as miR-29b, miR-148a, and miR-152, directly target DNA methyltransferases and indirectly modulate gene expression through epigenetic mechanisms[7]. Furthermore, both tumor suppressors and oncogenic factors influence miRNA expression and contribute to cancer pathogenesis[7,8].

Given that miR expression is tightly regulated, extraneous factors such as cellular stress, reduced oxygen availability, and hypoxia within the TME can alter the production and activity of mature miRs. Moreover, miRs can be encapsulated within extracellular vesicles (EVs) to facilitate intercellular communication in the TME[7]. EV-miRs can transform normal fibroblasts into cancer-associated fibroblasts (CAFs), which secrete cytokines and growth factors such as transforming growth factor (TGF)-β, interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α, all of which strongly contribute to tumor progression[5].

TUMORAL MICROENVIRONMENT AND ITS RELATIONSHIP WITH MIRNAS

The CRC TME is a heterogeneous microenvironment that includes cancer cells, fibroblasts, endothelial cells, and immune cells. The TME develops under hypoxic conditions, which trigger metabolic reprogramming associated with inflammation and promote tumor progression, immune evasion, and therapeutic resistance[9,10]. Under these conditions, hypoxia-inducible factors (HIFs) are expressed, leading to acidification of the microenvironment, which further drives stromal remodeling while suppressing the immune response[11]. HIF activity is regulated by signaling pathways including phosphatidylinositol 3-kinase (PI3K)-mammalian target of rapamycin (mTOR), Janus kinase (JAK)-signal transducer and activator of transcription (STAT) 3, nuclear factor kappa-B, mitogen-activated protein kinase (MAPK), Wnt/β-catenin, and Notch, all of which have been implicated in CRC development[12]. Table 1 includes miR’s presented in key alterations of CRC TME.

Table 1 Involved microRNA’s in key alterations of the colorectal cancer microenvironment[14,105,132-149].

miR	Cell type	Conditions	Context (hipoxy/inflammation/acidosis)	Key effect on TME	Ref.
miR-210	Epitelial tumor CRC	Progression tumor and metastasis	Hypoxia-upregulated	Classic “hypoxamiR”: Induced by HIF-1α; promotes adaptation to hypoxia, invasion and resistance	Coronel-Hernández et al[132]
miR-21	Tumor/epithelial cells and exosome-mediated transfer to stromal, endothelial, and immune cells	Primary tumor and progression tumor	Inflammation (IL-6/STAT3) and angiogenesis upregulated	Role as an oncomiR; suppresses PTEN and PDCD4; potentiates IL-6/STAT3 signaling, thereby promoting invasion and metastasis; contributes to the establishment of a pro-angiogenic TME	Lai et al[133]
miR-25-3p	Exosomes released from tumor epithelial cells to target endothelial cells	Progression tumor	Hypoxia/angiogenesis (TME) upregulated	Enhances vascular permeability and angiogenesis through the KLF2/KLF4 axis regulating VEGFR2, ZO-1, occludin, and claudin-5; contributing to the establishment of pre-metastatic niche	Xiong et al[134]
miR-1229	Exosomes released from tumor epithelial cells to target endothelial cells	Progression tumor	Hypoxia/angiogenesis (TME) upregulated	Promotes tube formation by inhibiting HIPK2 and enhancing VEGF	Soheilifar et al[135]
miR-320	Epithelial/estromal (colon) IL-6R/STAT3	Primary tumor and metastasis	Inflammation (CAC) downregulated	Inhibits IL-6R STAT3 signaling and reduces tumorigenesis in colitis-associated CRC	Wu et al[136]; Mjelle et al[137]
miR-590-3p (CAF-exosomal)	CAFs (exosomes) tumoral cells	Progression tumor	Damage response/TME stress upregulated	Confers radioresistance and activates PI3K/AKT; an example of TME remodeling by CAFs	Gou et al[138]
miR-34a	Epithelial cells to tumoral cells	Primary tumor supress metastasis	Hipoxia-inflammation/TME downregulated	p53mt-miR-34a suppresses EMT; IL-6/STAT3 downregulates miR-34a, establishing a pro-inflammatory and pro-EMT feedback loop	Włodarczyk et al[139]; Zhang et al[140]
miR-338-5p	Epithelial	Primary tumor, progression and drug resistance	Hypoxia/inflammation downregulated	Deficiency of miR-338-5p enhances IL-6/STAT3 signaling and confers resistance to oxaliplatin, fostering a pro-inflammatory TME	Valencia-Cervantes and Sierra-Vargas[141]
miR-19a	Epithelial	Progression tumor	Inflammation/survival upregulated (hypoxia conditions)	Suppression of PTEN-PI3K/AKT signaling promotes proliferation and invasion, further sustained by IL-6/STAT3 activation	Rahbar Farzam et al[142]
miR-135b-5p (CAF-exosomal)	CAFs (exosomes) epithelial and endothelial cells	Progression tumor	Hypoxia/inflammation upregulated	Exosomes derived from CAFs upregulate miR-135b-5p, leading to TXNIP suppression and enhanced tumor growth and angiogenesis	Umezu et al[143]; Shao et al[144]
miR-425-5p (exosomal)	Tumor (exosomes) macrophages/T	Progression tumor	Inmunosupression upregulated	Induction of M2-like polarization along with suppression of the pro-inflammatory T-cell response contributes to tumor progression and increased vascular permeability	Feng et al[145]
miR-934 (exosomal)	Tumor (exosomes) macrophages (liver)	Upregulated metastasis	Inflammation/metastasis	Induces M2 polarization and facilitates hepatic metastasis	Zhao et al[105]
miR-128-3p	Tumor (exosomes) epithelial	Primary tumor and progression	Inflammation (STAT3) upregulated	Activation of JAK/STAT3 and TGF-β/SMAD signaling promotes EMT and metastatic progression	Rahbar Farzam et al[142]
miR-9-5p	Epithelial tumoral to SLC9A1/NHE1 (antiport Na+/H+)	Progression tumor and metastasis	Acidosis upregulated	Modulation of NHE1 contributes to extracellular acidification, which in turn facilitates tumor invasion and metastasis	Wang et al[146]
miR-224-5p	Epithelial tumoral (HT29) SLC4A4/NBCe1 (Na+/HCO3-)	Progression	Acidosis upregulated	Repression of HCO3- transport diminishes pH buffering capacity, thereby exacerbating tumor acidosis	Yi and Yu[147]
miR-34a	Epithelial tumoral LDHA (lactate dehydrogenase A)	Primary tumor and progression	Acidosis downregulated	Acidosis suppress p53wt downregulation of miR-34a increases LDHA expression, leading to elevated lactate levels and acidosis; it also promotes EMT and therapy resistance	Li et al[14]; Xiong et al[134]
miR-143	Epithelial tumoral hexokinase 2	Primary tumor overexpresssion metastasis	Acidosis downregulated	Loss of this factor promotes glycolytic flux and lactate accumulation, exacerbating tumor acidosis	Gregersen et al[148]; Guo et al[149]

All the microRNAs have been validated in vitro and in vivo models, as well as in patient samples, except miR-590-3p for those that have only been detected in preclinical models and miR-320 in vivo/patients. miR: MicroRNA; CAF: Cancer-associated fibroblast; CRC: Colorectal cancer; IL: Interleukin; STAT: Signal transducer and activator of transcription; Na⁺: Sodium ion; H⁺: Hydrogen ion; HCO₃^-: Bicarbonate; LDHA: Lactate dehydrogenase A; TME: Tumor microenvironment; CAC: Colitis-associated colorectal cancer; HIF: Hypoxia-inducible factor; VEGFR2: Vascular endothelial growth factor receptor 2; ZO-1: Zonula occludens-1; PI3K: Phosphatidylinositol 3-kinase; AKT: Protein kinase B; JAK: Janus kinase; TGF: Transforming growth factor; pH: Potential of hydrogen.

The progression of the TME in CRC, driven by alterations in miR expression, is highly complex. Evidence suggests that dysregulated expression of specific miRs promotes the formation of aberrant crypts and rectal polyps while inducing microenvironmental changes in mouse models. These findings underscore the importance of detecting early miRs expression alterations within normal intestinal mucosa, as such changes may facilitate TME initiation and progression[13].

Among the diverse features of the TME, hypoxia is particularly prominent and fosters cellular proliferation, angiogenesis, and invasion, required for CRC progression. In contrast, other contributing factors, including the role of miRs in modulating inflammation and promoting extracellular acidification in CRC, remain less studied[14]. Table 1 summarizes the miRNAs directly or indirectly involved in hypoxia, inflammation, and extracellular acidification during CRC progression.

Several studies have identified oxygen deprivation as a driver for subsets of miRs collectively termed hypoxiamirs. In cancer, these include miRs that reinforce TME remodeling, such as miR-210, miR-2, and miR-30d[15]. Yang et al[16] further identified miR-197 and miR-26a as potential remodelers, whereas miR-375 appeared to play a protective role. These findings were correlated with poorer patient prognosis. Low oxygen conditions also correlate with activation of inflammatory signals such as TGF-β, platelet-derived growth factor, and other cytokines, as well as the induction of CAFs.

CAFs are important because they produce extracellular matrix components that facilitate tumor invasion, angiogenesis, and therapeutic resistance[10]. Savardashtaki et al[11] reported that CAF-derived exosomal miRs, miR-21, miR-199a, miR-181a, and miR-329, which are modulators of tumor-stromal crosstalk, contribute to aggressive cancer phenotypes. Inflammation and associated markers, i.e., TNF-α and nuclear factor kappa-B, are also subject to regulation by miRs[17].

Also, such effects have been observed in tumor-associated macrophages (TAMs), where elevated miR-155 activates Toll-like receptor signaling through nuclear factor kappa-B, hence mediating remodeling[18]. TAMs predominantly display an M2-like phenotype, accumulate in hypoxic tumor niches, and secrete pro-angiogenic and immunosuppressive factors such as vascular endothelial growth factor (VEGF), TNF-α, and matrix metalloproteinase-9, thereby supporting tumor growth and invasion[17]. Moreover, miR-24 and miR-218 reduce the cytotoxic effects of natural killer (NK) cells in CRC and lung adenocarcinoma, respectively, contributing to immune tolerance in the TME[19]. Remodeling of the TME is further promoted by the angiogenic activity of miR-155[20]. Another effect occurs when miR-21 is induced by chronic inflammation, enhancing chemoresistance and immune evasion through the PTEN and Toll-like receptor pathways[21].

IL-6 secreted by TAMs activates the JAK/STAT pathway and suppresses miR-506-3p expression in CRC cells. miR-506-3p functions as a tumor suppressor by targeting FoxQ1, thereby inhibiting CCL2 expression and macrophage recruitment. IL-6 also increases vimentin expression while reducing E-cadherin expression[22]. Furthermore, IL-6 activates the IL-6R/STAT3 pathway, transcriptionally activates STAT3, and suppresses the tumor suppressor miR-204-5p, which increases chemoresistance to 5-fluorouracil (5-FU) and oxaliplatin[23]. M2 macrophages with high expression of miR-21-5p and miR-155-5p bind to BRG1 in CRC, promoting metastasis[24].

Epithelial-mesenchymal transition (EMT) is a key step in metastasis, driven by cancer stem cells (CSCs), which maintain stemness and adaptability. During EMT, TNF-α induces miR-105 overexpression, targeting genes such as RAP2C, a small guanosine triphosphate-binding protein that promotes migration and invasiveness. miR-105 also enhances epithelial markers like E-cadherin, β-catenin, vimentin, and fibronectin[25]. Vimentin expression inversely correlates with miR-17-5p activity, which is associated with increased migration and invasiveness in LoVo and HT29 cells[26]. Moreover, miR-205 and let-7i are downstream targets of Snail, a zinc-finger transcription factor that induces EMT. Similarly, zinc-finger E-box binding homeobox 1 and E-box binding homeobox 2 are regulated by miR-200b, miR-200c, and miR-141, promoting early metastasis. With regard to growth, miR-4775 targets the SMAD7/TGF-β axis and RASSF6, promoting EMT and migration through Wnt signaling[27]. For survival, angiogenesis is supported by miR-92a, which targets TGF-β-R2, HIF-1α, and VEGFA[28]. In CRC, miR-92a promotes angiogenesis by downregulating Dickkopf-3 and claudin-11, and through the miR-92a/KLF4/p21 axis, enhances migration and proliferation[29]. In contrast, some miR’s exhibit anti-angiogenic activity; for example, p53-induced miR-1249 inhibits angiogenesis by targeting VEGFA and modulating the protein kinase B (AKT)/mTOR pathway. Similarly, miR-590-5p targets VEGFA and nuclear factor 90, while miR-25-3p promotes VEGF receptor 2 expression by regulating KLF2 and KLF4[27].

Feedback communication between CRC and endothelial cells allows transfer of miR’s to promote angiogenesis. CRC-derived miR-25-3p enhances vascular permeability and angiogenesis by targeting KLF2 and KLF4 in endothelial cells[30]. In addition, miR-21-5p suppresses KRIT1 in human umbilical vein endothelial cells (HUVECs), activating the β-catenin pathway and increasing VEGFA and CCND1 expression[31]. CRC-derived micro-vesicles containing miR-1246 promote angiogenesis by activating SMAD signaling in HUVECs through HIPK2 targeting. Suppression of HIPK2 allows MEF2C-mediated VEGF activation[32]. Furthermore, miR-320 loaded into micro-vesicles reduces GNAI1 levels in endothelial cells, enhancing JAK2/STAT3 signaling, VEGF production, proliferation, invasion, and angiogenesis[33].

CENTRAL MIR’S IDENTIFIED IN CRC PROGRESSION

MiRNAs regulate gene expression by coordinating complex molecular networks involved in CRC initiation, progression, metastasis, and response to therapy. Table 2 summarizes the main miRNAs associated with each consensus molecular subtype (CMS)(CMS1-CMS4) of CRC and highlights their clinical relevance. Notable miRNAs in CRC research include miR-145-5p[34,35], miR-16-5p[36,37], miR-199a-3p[38], miR-21-3p[39,40], and miR-21-5p[41], which collectively modulate overlapping pathways, such as PI3K/AKT, Ras/MAPK, Wnt/β-catenin, apoptosis regulators, DNA repair, angiogenesis, and EMT[42], as shown in Table 3. Dysregulation of these miRNAs disrupts cellular homeostasis, leading to uncontrolled proliferation, enhanced survival, EMT activation, stemness, metastatic potential, and resistance to chemotherapy, radiotherapy, and targeted therapies[31-84].

Table 2 MicroRNA’s associated with colorectal cancer molecular subtype and their clinical relevance[150,151].

CMS class	Molecular features	Frequency (%)	Immune phenotype	Prognosis	miR	Ref.
CMS1: Immune MSI	CIMP (increase); BRAFV600E m; hypermutated; KRASwt; TP53wt	14	Immune activation and infiltration LTC and NK	Intermediate prognosis; good early disease control but poor survival after relapse	miR-625 (increase), miR-31 (increase), miR-155 (increase)	Adam et al[150]
CMS2: Canonical (epithelial differentiation)	CIMP negative; BRAFwt; KRASwt; TP53m	37	WNT and MYC activation. Immune dessert	Best overall	miR-592 (increase), miR-552 (increase)	Adam et al[150]
CMS3: Metabolic	CIMP negative; BRAFwt; KRASm; TP53wt	13	Metabolic deregulation	Poor immunogenicity	miR-625 (increase)	Adam et al[150]
CMS4: Mesenchymal	CIMP negative; BRAFwt; KRASwt	23	Stromal infiltration (macrophages) TGF-β activator-CSC EMT and angiogenesis	Worse and poor survival. Resistant standard treatment	miR-625 (decrease), miR-143 (increase) (CMS4 vs CMS2); miR-200 (decrease), miR-218 (increase)	Adam et al[150]; Gherman et al[151]

CMS: Consensus molecular subtype; CIMP: CpG island methylator phenotype; wt: Wild type; m: Mutation; NK: Natural killer; TGF: Transforming growth factor; CSC: Cancer stem cell; EMT: Epithelial-mesenchymal transition; miR: MicroRNA.

Table 3 MicroRNA’s modulating colorectal cancer survivor and invasive pathways[31,36,37,39,47,53,58-60,63,70-72,76,77,79,82-84,98,124,152-169].

miR	Expression	Study model	Target genes	Modulated pathways	Ref.
miR-145-5p	Downregulated	In vitro	N-RAS and IRS1	Cell proliferation by AKT inactivation	Yin et al[152]
miR-145-5p	Downregulated	In vitro	CDCA3	Cell proliferation, migration, invasion, EMT	Chen et al[84]
miR-145-5p	Downregulated	In vitro	TWIST1	Migration and invasion	Shen et al[153]
miR-145-5p	Downregulated	In vitro	MAPK1	Cell proliferation, migration, and invasion	Yang et al[154]
miR-145-5p	Downregulated	In vitro	SIP1	Cell proliferation, migration, and invasion	Sathyanarayanan et al[155]
miR-145-5p	Downregulated	In vitro	PAK4	Migration and invasion	Sheng et al[59]
miR-145-5p	Downregulated	In vitro and in vivo	p70S6K1	Tumor growth and angiogenesis by HIF-1 and VEGF	Xu et al[156]
miR-145-5p	Downregulated	In vitro and in vivo	LASP1	Invasion and metastasis	Wang et al[58]
miR-145-5p	Downregulated	In vitro	CXCL1 and ITGA2	Cell proliferation and migration	Zhuang et al[60]
miR-16-5p	Downregulated	In vitro and in vivo	PVT1	Cell proliferation, migration, and invasion by VEGFA and p-AKT	Rahmati et al[98]
miR-16-5p	Downregulated	In vitro and in vivo	ITGA2	Apoptosis and tumor growth	Xu et al[36]
miR-16-5p	Downregulated	In vitro	BIRC5	Apoptosis, cell proliferation, and angiogenesis	Aslan et al[47]
miR-16-5p	Downregulated	In vitro	FOXK1	Cell proliferation and angiogenesis by PI3K/AKT/mTOR signaling	Huang et al[37]
miR-16-5p	Downregulated	In vitro and in vivo	HMGA2	Migration, invasion, and EMT by β-catenin pathway	Cai et al[63]
miR-199a-3p	Downregulated	In vitro	PAK4 and BCAR3	Cell proliferation, migration and invasion	Hou et al[70]
miR-199a-3p	Downregulated	In vitro	FN1	EMT by N-cadherin and vimentin	Lin et al[71]
miR-199a-3p	Downregulated	In vitro	NLK	Metastasis	Han et al[72]
miR-199a-3p	Downregulated	In vitro	TGFBR1 and PDGFRB	Cell proliferation by MAPK-signaling	Slattery et al[157]
miR-21-3p	Upregulated	In vitro and in vivo	SMAD7	EMT through the increase of N-cadherin	Jiao et al[39]
miR-21-3p	Upregulated	In vitro	RBPMS	Migration, invasion, and apoptosis by Smad4/ERK signaling	Hou et al[53]
miR-21-5p	Upregulated	In vitro and in vivo	KRIT1	Angiogenesis through β-catenin signaling pathway, VEGFA and CCND1	He et al[31]
miR-21-5p	Upregulated	In vitro and in vivo	PDCD4 and TGFBR2	Stemness promotion by upregulation of β-catenin, c-MYC and cyclin-D1	Yu et al[158]
miR-21-5p	Upregulated	In vitro and in vivo	PTEN	Apoptosis, cell proliferation and invasion	Wu et al[76]; Lin et al[77]
miR-21-5p	Upregulated	In vitro and in vivo	CHL1	Cell proliferation, invasion and tumor growth	Yu et al[79]
miR-21-5p	Downregulated	In vitro	TGFBI	Pyroptosis	Jiang et al[82]
	Downregulated	In vitro	SATB1	Cells sensitive to chemoradiation	Lopes-Ramos et al[83]
miR-4461	Downregulated	In vitro	COPB2	Cell proliferation, migration, and invasion	Chen et al[159]
miR-449a	Downregulated	In vitro	HDAC1, TGFB, SATB2, ADAM10, MYC, and MAPK1	Cell proliferation, invasion and poor survival	Ishikawa et al[160]
miR-519d-3p	Downregulated	In vitro	TROAP	Apoptosis, cell proliferation, migration, and invasion	Ye and Lv[161]
miRNA-31	Upregulated	In vitro	STK40	NF-κB signaling pathway and invasion	Zhu and Xue[162]
miR-200a	Upregulated	In vitro	PTEN	Cell proliferation, migration and invasion	Li et al[163]
miRNA-552	Upregulated	In vitro	PTEN	Poor prognosis	Im et al[164]
miRNA-552	Upregulated	In vitro and in vivo	ADAM28	Cell proliferation, migration and tumor growth	Wang et al[165]
miR-592	Upregulated	In vitro	mTOR and FOXO	Cell proliferation, migration and invasion	Pan et al[166]
miR-708 and miR-31	Upregulated	In vitro	CDKN2B	Cell proliferation, invasion and apoptosis resistance	Lei et al[167]
miR-25	Upregulated	In vitro and in vivo	SIRT6	Metastasis through inhibited LIN28B/NRP1 axis	Wang et al[168]
miR-130b-3p	Upregulated	In vitro and in vivo	CHD9	Cell proliferation and tumor growth	Song et al[169]
miRNA-221	Upregulated	In vitro and in vivo	TP53BP2	Cell proliferation through TP53 inhibition	Ali et al[124]

miR: MicroRNA; mTOR: Mammalian target of rapamycin; AKT: Protein kinase B; EMT: Epithelial-mesenchymal transition; HIF: Hypoxia-inducible factor; VEGF: Vascular endothelial growth factor; p-AKT: Phospho-protein kinase B; PI3K: Phosphatidylinositol 3-kinase; MAPK: Mitogen-activated protein kinase; ERK: Extracellular regulated protein kinases; NF-κB: Nuclear factor kappa-B.

PI3K/AKT SIGNALING REPRESENTS A MAJOR AXIS OF CONVERGENCE

The tumor-suppressive miR’s miR-145-5p and miR-16-5p inhibit PI3K/AKT signaling, reduce mesenchymal marker expression (N-cadherin and vimentin), restore epithelial markers such as E-cadherin, and suppress proliferation, migration, and invasion[37,44,63,85]. In parallel, miR-16-5p inhibits mTOR activation and modulates metabolic reprogramming through the ALDH1A3/PKM2 axis, further suppressing tumor growth[64]. In contrast, oncogenic miR-21-3p and miR-21-5p activate PI3K/AKT, upregulate transcription factors such as E2F-1 and Twist, and enhance β-catenin nuclear localization, promoting survival, EMT, stemness, and chemoresistance[53,77,80]. The net outcome of PI3K/AKT signaling in CRC depends on the relative expression of these antagonistic miRNAs, illustrating a tightly regulated network.

APOPTOSIS AND CELL CYCLE REGULATION ARE CO-MODULATED BY MULTIPLE MIR’S

Conversely, miR-21-3p and miR-21-5p inhibit apoptosis by upregulating multidrug resistance proteins (multidrug resistance-1, multidrug resistance protein 1), enhancing antioxidant defenses (glutathione, superoxide dismutase, glutathione S-transferase-π), and repressing tumor suppressors such as PDCD4, PTEN, and SATB1, conferring resistance to chemotherapy and radiotherapy[75,80,83,86]. miR-199a-3p contributes to apoptosis regulation by targeting NLK, PAK4, and SLITRK6, reducing proliferation, migration, and invasion[70-73]. The interplay among these miR’s determines the balance between cell death and survival in CRC, influencing tumor aggressiveness.

EMT, STEMNESS, AND METASTATIC POTENTIAL ARE SIMILARLY CO-REGULATED

MiR-145-5p represses EMT- and CSC-associated transcription factors (OCT4, SOX2, and KLF4), thereby inhibiting spheroid formation and stem-like properties[35,44,85]. miR-16-5p suppresses HMGA2 and FOX-1 expression, limiting EMT and metastatic potential[37,63].

In contrast, miR-21-5p promotes CSC traits via Wnt/β-catenin activation and TGF-βR2 suppression, leading to nuclear β-catenin accumulation and upregulation of epithelial cell adhesion molecule and catenins[75,80,83,84,86]. miR-21-3p enhances EMT, migration, and invasion, whereas miR-199a-3p reduces mesenchymal marker expression under hypoxic conditions, highlighting context-dependent regulation[70-73]. Collectively, these miR’s establish a dynamic balance that dictates CRC invasiveness and recurrence.

Angiogenesis and microenvironmental modulation are critical for tumor progression. miR-145-5p inhibits VEGF, HIF-1α, and N-RAS, reducing neovascularization. miR-16-5p suppresses VEGFA expression, impairing vascular support for tumors. In contrast, miR-21-5p enhances angiogenesis by repressing KRIT1 and activating β-catenin signaling, promoting vascular permeability and neovascularization[31,42]. miR-199a-3p regulates endothelial inflammation and barrier function, indirectly influencing tumor angiogenesis and metastatic niche formation[36,87].

Therapy resistance arises from the combined effects of these miRNAs on DNA repair, survival signaling, EMT, stemness, and drug efflux. miR-145-5p modulates the 5-FU response via the ATF4/miR-145/HDAC4/p53 axis and RAD18-mediated DNA repair, while reducing cetuximab resistance by targeting RREB1 and Ras/MAPK signaling[44,88,89]. miR-16-5p enhances chemotherapy and radiotherapy sensitivity by targeting KRAS, BCL2, and the PI3K/AKT/mTOR pathway, and its low expression predicts poor response. miR-199b-3p contributes to cetuximab resistance via Wnt/β-catenin signaling and CRIM1 regulation; its inhibition restores drug sensitivity both in vitro and in vivo[90-93]. miR-21-3p promotes cisplatin and paclitaxel resistance by enhancing drug efflux, antioxidant defense, and survival signaling[86]. miR-21-5p mediates resistance to 5-FU, oxaliplatin, and radiation by repressing SATB1, PDCD4, PTEN, and TIMP3[77,79,80,83,94,95]. Contextually, miR-21-5p can sensitize cells to chemoradiotherapy in rectal cancer, illustrating its dual role as both a resistance mediator and a therapeutic target.

Collectively, miR-145-5p, miR-16-5p, miR-199a-3p, miR-21-3p, and miR-21-5p form a highly interconnected regulatory network[43-51,79,80]. Their coordinated modulation of PI3K/AKT, Ras/MAPK, Wnt/β-catenin, apoptosis, DNA repair, EMT, stemness, and angiogenesis underlies CRC progression, metastasis, and therapy resistance[53-84]. Therapeutic strategies targeting these miRs, individually or in combination[31-38,66], offer potential to improve chemosensitivity[39-42,76,79,85], radiosensitivity[43-51,79,80], and overall clinical outcomes, emphasizing the importance of understanding miR crosstalk[53-84,89] and pathway integration in precision oncology[73-100]. Table 4 provides an overview of the miRs linked to treatment response. Below are selected examples highlighting specific miRs and the molecular mechanisms by which they influence therapeutic outcomes in CRC.

Table 4 MicroRNA’s associated with treatment response and therapeutic outcomes in colorectal cancer[26,86,88,91,93,94,170-186].

miR	Mechanism	Study model	Target	Response therapy	Ref.
miR-153-5p	Overexpression	In vitro	BCL-2	Sensibilize oxaliplatin	He et al[170]
miR-145-5p	Decreased	In vitro	BIRC5, Fli-1	Sensibilize, 5-FU, oxaliplatin	Xie et al[171]
miR-1451	Overexpression	In vitro and in vivo	SNAI1, HDAC4 and ATF4	Sensibilize radiotherapy and 5-FU	Zhao et al[88]; Zhu et al[172]
miR-150-5p	Overexpression	In vitro and in vivo	BIRC5, CASP7, VEGFA	Anti-VEGF	Slattery et al[173]; Chen et al[174]
miR-195-5p	Expression	In vivo	GDPD5	Sensibilize 5-FU	Feng et al[175]
	Overexpression	In vitro	BIRC5, BCL-2, YAP	Sensibilize, doxorrubicin and oxaliplatin	Qu et al[176]; Poel et al[177]
miR20b-5p1	Expression	In vitro and in vivo	CTSS, ADAM9, EGFR, CCND1/CDK4/FOXM1 axis	Sensibilize 5-FU	Fu et al[178]; Yang et al[179]
miR21-3p	Overexpression	In vitro	MDR1 and MRP1	Cisplatin resistance	Dong et al[86]
miR21-5p	Overexpression	In vitro	SATB1, PTEN, MSH2, PDCD4	Chemoresistance (oxaliplatin)	Chen et al[94]
miR497-5p	Overexpression	In vitro and in vivo	KSR1, BCL-2, IGF1-R	Sensibilize 5-FU, oxaliplatin	Poel et al[177]; Wang et al[180]
miR-17-5p	Overexpression	In vitro and in vivo	MFN2, vimentin STAT3, E2F1, HMGA2, SOX4, TWIST1, and EGFR	Resistance oxaliplatin, irinotecan, and fluorouracil	Kim et al[26]; Sun et al[181]
miR-199b-3p; miR-199a-5p	Overexpression	In vitro and in vivo	CRIM1	Resistance cetuximab, sensitive cetuximab	Kim et al[26]; Han et al[93]; Mussnich et al[182]
miR-124	Overexpression	In vitro and in vivo	PRRX1	Sensitive radiotherapy (inhibition PRRX1)	Zhang et al[183]
miR-1226-5p	Overexpression	In vitro	IRF1	Resistance radiotherapy	Choi et al[184]
miR-7-5p	Downregulated	In vitro and in vivo	KLF4	Resistance radiotherapy	Shang et al[185]
miR-16-5p	Downregulated	In vitro	FOXK, PI3K/AKT/mTOR	Resistance radiotherapy	Mousavikia et al[91]
miR-423-5p	Downregulated	In vitro	BCL-2	Resistance radiotherapy	Shang et al[186]

¹Expressed on advanced cancer.

miR: MicroRNA; MDR1: Multidrug resistance-1; MRP1: Multidrug resistance protein 1; PI3K: Phosphatidylinositol 3-kinase; AKT: Protein kinase B; mTOR: Mammalian target of rapamycin; 5-FU: 5-fluorouracil; VEGF: Vascular endothelial growth factor.

COMMUNICATION BETWEEN CANCER CELLS AND THE TME: THE MODULATORY IMPACT OF MIR’S IN CRC

In CRC, the interaction between tumor cells and the TME is orchestrated through a dynamic exchange of signals mediated by EVs, cytokines, growth factors, and non-coding RNA[101-103]. EVs including exosomes, micro-vesicles, and apoptotic bodies act as critical carriers of miR’s, thereby regulating gene expression and sustaining tumor stromal communication. TAM-derived EVs often promote malignancy by delivering miR-21, miR-155, and miR-105, which enhance angiogenesis, immune evasion, and tumor growth[20,21]. In the immune evasion context, miR-934 and miR-106b-5p inhibit M1 macrophage polarization through the upregulation of miR-19a-3p and downregulation of miR-155[18,104-107]. CAFs also display distinct miR signatures, with overexpression of miR-345-5p, miR-17-5p, miR-20a-5p, miR-122-5p, miR-93-5p, and miR-590-3p, together with reduced levels of miR-200b-3p, contributing to stromal remodeling[108-113].

Tumor cells further evade immune surveillance by expressing miR-24 and miR-218, which suppress NK cell cytotoxicity, and by miR-155–mediated inhibition of T-cell responses[114-116]. Moreover, tumor-derived EVs enriched on miR-23a-3p, miR-1246, miR-25-3p, and miR-21-5p activate endothelial cells, promoting angiogenesis through tip-cell formation[30-32]. This process is modulated by pro-angiogenic miR’s (e.g., miR-92a) and counterbalanced by anti-angiogenic miR’s (e.g., miR-1249 and miR-590-5p). Similarly, tumor-secreted miR-200b, miR-200c, miR-141, and miR-105 drive EMT, which sustains CSC maintenance through the cooperative action of miR-21, miR-145-5p, miR-16-5p, and miR-199a-3p[25,27,56,73,77,80,117,118]. Collectively, these findings underscore the intricate miR-mediated crosstalk between cancer cells and the TME, which drives tumor progression, metastasis, therapy resistance, and immune tolerance. Importantly, this dual role positions EV-carried miRNAs not only as mediators of malignancy but also as promising therapeutic targets (Figure 1).

Figure 1 Modulation of microRNA’s dynamics in the colorectal cancer microenvironment. There is a crosstalk between cells inside tumor microenvironment that drives microRNA’s dysregulation, leading to immune evasion, decreased cytotoxicity, therapy resistance, angiogenesis, and metastasis of colorectal cancer. NK: Natural killer; miR: MicroRNA; CAF: Cancer-associated fibroblast; TAM: Tumor-associated macrophage; EC: Endothelial cell; CRC: Colorectal cancer; CSC: Cancer stem cell.

MIR-BASED TARGETED THERAPY FOR CRC

Currently, most clinical trials (n = 11) evaluating miRNAs in CRC have focused on their roles as biomarkers and predictors of tumor stage. These studies, registered in the United States National Library of Medicine (https://clinicaltrials.gov/), highlight the diagnostic and prognostic potential of miRs. Therapeutically, two main strategies are being pursued: (1) The use of miR mimics to restore tumor-suppressive miRs; and (2) The inhibition of oncogenic miRs using antisense oligonucleotides, locked nucleic acids (LNAs), or miR sponges[119,120]. Although viral and liposomal systems have been employed to improve mimic delivery, clinical translation has been limited by toxicity, off-target effects, and immune-related complications[121,122].

Among these mimics, MRX34 (a liposomal miR-34a mimic) represented the first in-human clinical trial, demonstrating preliminary antitumor activity in refractory solid tumors before termination due to severe immune-mediated toxicities[123]. Other candidates, such as TargomiRs (miR-16 mimic) and INT-1B3 (miR-193a-3p mimic), have shown encouraging safety and preclinical efficacy. However, their clinical progress has been slowed by modest outcomes and financial constraints. In contrast, inhibitors targeting oncogenic miRs have produced more favorable results. For example, LNA-i-miR-221 demonstrated an excellent safety profile and durable clinical benefit in CRC patients, while coboomarsen (anti-miR-155) improved safety and quality-of-life outcomes in lymphoma patients before its discontinuation for strategic reasons[124,125]. More recently, TTX-MC138 (anti-miR-10b) entered early-phase clinical trials for metastatic cancers, and lademirsen (anti-miR-21) was well tolerated in patients with Alport syndrome, although it failed to provide significant clinical benefits[126-128]. Collectively, these findings suggest that miR inhibition may represent a safer and more feasible therapeutic approach than mimic-based strategies, while highlighting the need for further optimization.

Given the limitations of conventional delivery systems, there is growing interest in developing novel, efficient, and non-cytotoxic vehicles. Cell-derived carriers, particularly exosomes, have emerged as promising delivery platforms for miRs[129]. Among these, mesenchymal stem cell (MSC)-derived exosomes are especially attractive because of their clinical applicability in gene therapy delivery systems (e.g., IL-2, interferon, and TNF-related apoptosis-inducing ligand)[130,131]. Table 5 presents selected examples of MSC-derived exosomes engineered for miRNA delivery, which may offer a potential therapeutic avenue for CRC treatment.

Table 5 Mesenchymal stem cell-derived exosome-based strategies for microRNA delivery in colorectal cancer[36,159,187-192].

Exo-miR	Cell delivery	Study model	Mechanism	Ref.
Exo-miR30a; miR222	hCC-MSC	In vitro and in vivo	Growth (increase), migration and metastasis (inhibit MIA3)	Du et al[187]
Exo-miR4461	hBM-MSC	In vitro	The proliferation, migration and invasion by down-regulating COPB2 (decrease)	Chen et al[159]
Exo-miR22-3p	hBM-MSC	In vitro	Proliferation and invasion (RAP2B/PI3K/AKT pathway) (decrease)	Wang and Lin[188]
Exo-miR-16-5p	hBM-MSC	In vitro and in vivo	Proliferation, invasion and migration (downregulating ITGA2) (decrease)	Xu et al[36]
Exo-miR431-5p	hUC-MSC	In vitro and in vivo	Progression (suppress PRDX1) (decrease)	Qu et al[189]
Exo-anti-miR-146b-5p ASO	hUC-MSC	In vitro and in vivo	Proliferation, migration and EMT (inhibition of Smad signaling) (decrease)	Yu et al[190]
Exo-miR-486-5p	hUC-MSC	In vitro	Glycolysis and cell stemness by targeting NEK2 (decrease)	Cui et al[191]
Exo-miR-431-5p	hUC-MSC	In vitro and in vivo	Cell growth and progression by inhibiting PRDX1 (decrease)	Qu et al[189]
1Exo-miR-199a-3p	AMSCs	In vitro and in vivo	Sensitized to chemotherapeutic agents by targeting mTOR pathway	Lou et al[192]

¹Hepatocellular carcinoma.

miR: MicroRNA; ASO: Antisense oligonucleotides; hCC-MSC: Human cancer cells-mesenchymal stem cell; hBM-MSC: Human bone marrow-mesenchymal stem cell; hUC-MSC: Human umbilical cord- mesenchymal stem cell; AMSC: Adipose tissue-derived mesenchymal stem cell; PI3K: Phosphatidylinositol 3-kinase; AKT: Protein kinase B; EMT: Epithelial-mesenchymal transition; mTOR: Mammalian target of rapamycin.

PERSPECTIVES

While the role of the microenvironment in modulating miRs and influencing CRC prognosis and treatment has been acknowledged, ongoing research continues to clarify the mechanisms underlying specific regulatory targets that are critical for understanding tumor cellular and immunological characteristics.

The present work provides an extensive examination of miR’s implicated in carcinogenesis, expressed in CRC, and regulated by molecular pathways associated with tumor progression and resistance. The continued investigation of tissues and circulating miR’s is crucial, as it represents a promising approach to developing noninvasive diagnostic tools capable of predicting treatment response and recurrence risk.

Because the functional role of each miR varies greatly, numerous miR’s, especially newly identified ones, remain under intensive study. Modern methodologies for RNA analysis, exosome isolation, and expression panel analyses have led to considerable improvements in the identification of biomarkers, predictive signatures, and therapeutic targets. A major challenge in advancing the functional understanding of miR’s in CRC is the lack of preclinical models that accurately replicate the complexity of the TME. The use of organoids, three dimensional models, and co-culture systems incorporating immune and vascular cells provides an effective approach for validating miR expression levels. Such models can yield a more precise understanding of intercellular interactions and guide the development of strategies to modulate miR’s, which may directly influence the response to conventional treatments, including immunotherapy, radiotherapy, and chemotherapy, thereby creating opportunities to overcome tumor resistance and improve patient prognosis.

To date, miR-based therapies have faced substantial challenges, particularly in developing strategies that ensure efficient and stable delivery of miR’s to target sites without inducing cytotoxicity. Promising results have been observed when MSCs were used as delivery vehicles; however, these strategies have thus far only been evaluated in in vitro and in vivo models, and their effectiveness in clinical settings remains to be determined.

Ultimately, integrating miR profiles with genomic and clinical data is essential for advancing personalized medical strategies for CRC. Implementing such an approach could enable the development of customized therapies tailored to the specific molecular and biological features of each patient. Achieving meaningful progress in this direction will require a multidisciplinary effort that brings together molecular biology, preclinical modeling technologies, and clinical research.

CONCLUSION

In summary, our findings emphasize the regulatory roles of miRNAs in CRC that must be interpreted within the context of TME heterogeneity. While certain mechanisms are broadly shared across diverse TMEs, others are restricted to specific molecular subtypes or cellular contexts. MiRNAs emerge as central modulators of CRC progression, acting as both oncogenic and tumor-suppressive molecules that shape key biological processes, including epithelial mesenchymal transition, stemness acquisition, and therapeutic response. Their expression profiles not only hold prognostic value but also highlight promise as biomarkers for treatment stratification. Although definite clinical validation is still lacking, innovative strategies particularly stem cell-derived exosomes for targeted delivery of miRNAs or anti-miRNAs offer a path towards more precise and personalized therapies. Continued research in this field is therefore essential to improve patient outcomes and advance our understanding of CRC biology.

ACKNOWLEDGEMENTS

We are grateful to the students of Universidad Autonoma de Nuevo Leon for their assistance in the literature analysis that contributed to this manuscript.