MicroRNA 195, lactate dehydrogenase 5, phosphatase and tensin homologue in colorectal cancer: Clinicopathology and prognosis

Abstract

BACKGROUND

Colorectal cancer (CRC) is a prevalent gastrointestinal malignancy, with its pathogenesis involving dysregulation of multiple genes, including adenomatous polyposis coli and p53. Emerging evidence suggests that microRNA 195 (miR195) plays a critical role in carcinogenesis by modulating the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) signaling pathway through phosphatase and tensin homologue (PTEN), thereby influencing cellular metabolism. Loss of PTEN function leads to hyperactivation of PI3K/AKT signaling pathway, resulting in upregulated expression of lactate dehydrogenase-5 (LDH-5) and promoting the tumor progression.

AIM

To explore the clinical relevance of miR195, LDH-5, and PTEN expression patterns in CRC patient tissues and their association with clinicopathological features and prognosis.

METHODS

We enrolled 53 CRC patients who received surgical resection at our hospital from January 2020 to February 2022. Fresh tumor tissues and paired adjacent normal tissues (> 5 cm from the tumor margin) were collected. The mRNA expression of miR195 was quantified by real-time quantitative polymerase chain reaction, while the protein expression of LDH-5 and PTEN were assessed via immunohistochemistry. Differences in molecular expression between tumor and adjacent normal tissues were compared, along with their correlations with clinicopathological parameters and prognosis.

RESULTS

The positive rate of miR195 in CRC tissues (35.85%) was significantly lower than that in adjacent normal tissues (90.57%). LDH-5 displayed a higher positive rate (79.25%) in the tissues compared to normal tissues (11.32%), while PTEN expression was markedly reduced in tumors (28.30% vs 94.34%, P < 0.05). Elevated expression of miR195 was observed in CRC tissues from patients with earlier tumor, node, metastasis (TNM) stages and without lymph node metastasis. Conversely, higher expression of LDH-5 was associated with advanced TNM stages, lower differentiation grades, and the presence of lymph node metastasis. Additionally, PTEN expression was higher in patients with smaller tumor diameters and no lymph node metastasis (P < 0.05). In CRC tissues, miR195 showed a negative correlation with LDH-5 (r = -0.883, P = 0.015) but a positive correlation with PTEN (r = 0.429, P = 0.006). LDH-5 was negatively associated with PTEN (r = -0.396, P < 0.001). Patients with miR195 positivity, LDH-5 negativity, and PTEN positivity demonstrated significantly better prognosis (P < 0.05).

CONCLUSION

Low miR195 and PTEN expression, coupled high LDH-5 expression could constitutes a hallmark molecular signature of CRC progression. These signature may act as potential markers for diagnosis and disease assessment, and prognostic evaluation in CRC patients, eventually improving CRC management.

Key Words: Colorectal cancer; MicroRNA 195; Lactate dehydrogenase-5; Phosphatase and tensin homologue; Clinicopathology; Prognosis

Core Tip: Colorectal cancer (CRC) incidence has shown a sustained annual increase with a notable trend toward younger-onset cases, significantly affecting public health. In this retrospective cohort study, we systematically conducted clinical data of 53 CRC patients, performing quantitative comparison of microRNA 195 (miR195), lactate dehydrogenase-5 (LDH-5), and phosphatase and tensin homologue (PTEN) expression profiles between tumor tissues and matched adjacent normal tissues, as well as their correlation with clinicopathological parameters and prognosis. Our findings revealed that reduced miR195 and PTEN expression, coupled high LDH-5 expression exhibited strong mechanistic associations with CRC pathogenesis and disease progression, suggesting that molecular alterations as potential utility as a novel diagnostic indicators for precision oncology applications.

INTRODUCTION

Colorectal cancer (CRC) is a prevalent malignant tumor of the digestive system originating from abnormal proliferation of the colorectal epithelium[1]. The disease exhibits a characteristic clinical development: Early-stage lesions typically remain asymptomatic, while advanced stages manifest with clinically significant symptoms including altered bowel habits, hematochezia, and abdominal discomfort. In terminal stages, patients often develop systemic manifestations such as cachexia and severe anemia. Recent epidemiological data from China (2022), the number of new cases of CRC was 517100 (10.7% of total cancer incidence), ranking second. And CRC mortality was 240000 (9.3% of total), ranking fourth[2]. The molecular pathogenesis of CRC has become increasingly elucidated recently. For CRC patients, current diagnostic paradigms emphasize comprehensive preoperative evaluation incorporating molecular profiling, where histological examination serves as the diagnostic gold standard while providing critical prognostic information through tumor grading and molecular characterization[3]. Numerous studies have reported that CRC result from the cumulative effects of multiple genetic and epigenetic alterations[4-6]. In CRC patients, proto-oncogenes are often highly expressed, while tumor suppressor genes are functional inactivated. In this context, it is of great significance to explore molecular markers correlated with the development, progression, and prognosis of CRC for clinical prevention and treatment.

MicroRNA 195 (miR195), a member of the non-coding RNA microRNA family, serves as an important regulator in multiple solid tumors, modulating tumor cells' metastasis, invasion, and apoptosis via various pathways. miR195 downregulation has also been found to contribute to drug resistance in cancer cells[7], making its potential as a diagnostic biomarker for cancer diagnosis. Tian et al[8] demonstrated that miR497HG and its embedded miR195 promoted breast cancer progression and tamoxifen resistance in estrogen receptor-positive (or ER+) patients by regulating the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) signaling pathway, serving as a biomarker for predicting disease progression and drug resistance. Lactate dehydrogenase-5 (LDH-5), a muscle-enriched isozyme of lactate dehydrogenase critical for lactate metabolism, has emerged as an important regulator of tumor proliferation, survival and metastasis[9]. Chen et al[10] unraveled that 182 kDa tankyrase-1-binding protein (TAB182) can modulate glycolytic metabolism by controlling lactate dehydrogenase A (LDHA) transcription, hence influencing cellular responses to radiation therapy. The protein encoded by phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor gene, renowned for its dual-specificity phosphatase activity, and participates in the regulation of multiple processes such as cell growth and differentiation, and[11]. Extensive research has validated PTEN's critical tumor-suppressive functions in colorectal carcinogenesis[12,13].

While miR195 is widely recognized as a tumor suppressor across multiple malignancies, emerging evidence suggests its function may be context-dependent, with some studies reporting paradoxical oncogenic properties in specific cellular environments[14]. Moreover, while the individual roles of miR195, LDH-5, and PTEN in cancer biology have been partially characterized, their collective association with CRC clinicopathological features and patient outcomes remains poorly elucidated. To address these critical knowledge gaps, we designed this comprehensive study, aiming to provide novel biomarker signature for the prevention and treatment of CRC patients.

MATERIALS AND METHODS

Source of patient tissue specimens

Paired CRC tumor and adjacent normal tissues (> 5 cm away from tumor margin) were collected from 53 CRC patients undergoing surgical resection in our hospital from January 2020 to February 2022. After being confirmed by two independent experienced pathologists, all tissue specimens were cut into 0.5 mm³ pieces and stored in liquid nitrogen at -80 °C for subsequent analysis. All patients had not received radiotherapy or chemotherapy prior to surgery, with an age range of 31-85 years and an average age of (58.71 ± 6.02) years. There were 30 males and 23 females. Tumor sites: 28 cases of colon cancer and 25 cases of rectal cancer; tumor, node, metastasis (TNM) staging: 10 cases of stage I, 11 cases of stage II, 17 cases of stage III, and 15 cases of stage IV; tumor diameter: ≥ 2 cm in 23 cases and < 2 cm in 30 cases; differentiation degree: 11 well differentiated cases, 25 moderately differentiated cases, and 17 poorly differentiated cases; presence of lymph node metastasis: 29 cases showing presence, and 24 cases showing absence. This study was approved by the hospital's ethics committee and was conducted in keeping with the Declaration of Helsinki. Written informed consent was obtained from all participants prior to tissue collection.

Real-time fluorescence quantitative polymerase chain reaction for detecting miR195 mRNA expression in tissue specimens

Frozen tissue samples were pulverized and homogenized using liquid nitrogen. Total RNA was extracted using the miRNeasy Mini Kit (QIAGEN) following the instructions. Then, the SYBRPrimeScript miRNA reverse transcription polymerase chain reaction (PCR)[15] kit (Takara) was adopted to reversely transcribe the total RNA into cDNA according to the kit instructions. The obtained cDNA was utilized as a template. Real-time fluorescence qPCR was employed for examining the mRNA expression level of miR195 in the specimen tissues, with U6 as the internal reference for normalization. The upstream primer of miR195 was 5'-cgtagcagcacagaaatattggc-3', and the downstream primer was 5'-ccagtctcagggtccgaggtattc-3'. Real-time fluorescence qPCR was carried out in LightCycler 480. Each experiment was conducted in triplicate, and the average values were calculated. The relative expression of miR195 was expressed using 2^-△Q, and the 2^-△△Q method was introduced for calculating its relative quantification (with U6 as the internal reference). If the 2^-△△Q value is < 2.00, the sample is considered positive.

The immunohistochemical method for testing LDH-5 and PTEN protein expression levels in specimen tissues

Frozen tissue specimens were fixed with 4% neutral paraformaldehyde. Following fixation, tissues were dehydrated, embedded in paraffin, sectioned consecutively. For immunohistochemical staining[16], the specimens were deparaffinized, rehydrated, and incubated in the 3% hydrogen peroxide solution at 37 °C for 20 minutes. Next, the specimens were subjected to high-pressure heating for 4 minutes, cooled to room temperature, blocked with goat serum, and placed in a water bath at 37 °C for 15 minutes. Primary antibodies were applied and incubated at 37 °C for 1 hour, followed by secondary antibodies (incubated at 37 °C for 30 minutes) and horseradish peroxidase (incubated at 37 °C for 30 minutes). At last, phosphate buffered saline was used for washing, and 3,3'-diaminobenzidine was employed for visualization.

Assessment of immunohistochemistry results

The immunohistochemical slides were evaluated independently by two pathologists using a double-blind protocol to ensure objective scoring. LDH-5 and PTEN exhibited predominant cytoplasmic localization. The semi-quantitative scoring method[17] was adopted for assessing the immunohistochemical staining results. Scoring rules: (1) Cells with no staining are scored as 0; weak staining is scored as 1; and intense staining is scored as 2 points; (2) Positive cells accounting for < 5%, 0 points; 5%-25%, 1 point; 26%-50%, 2 points; > 50%, 3 points; and (3) If the sum of the scores from the two criteria above is 0, the result is considered negative; a score of 1 or higher is considered positive.

Data collection and follow-up investigation

The clinical data of all patients were collected, including age, sex, tumor site, tumor diameter, histological differentiation grade, TNM staging, and lymph node metastasis status. We also analyzed the correlation of miR195, LDH-5, and PTEN expression with clinicopathological parameters. After the patients were discharged, they were followed up for 3-years via telephone and outpatient visits to assess their prognosis. No cases were lost during follow-up period. The overall survival was defined as time from postoperative day 1 to either date of death of the last confirmed alive status. The relationship between the expression levels of miR195, LDH-5, and PTEN and patient prognosis was analyzed.

Statistical analysis

SPSS22.0 software was introduced for data processing and analysis in our study. Measurement data were represented as (mean ± SD), with t-tests conducted. Enumeration data were exhibited as percentages, with χ² tests performed for analysis. Contingency table correlation analysis was carried out for miR195, LDH-5, and PTEN. Kaplan-Meier survival curves were plotted to analyze the relationship between the expression levels of miR195, LDH-5, and PTEN and patient prognosis. The Log-rank test was employed for statistical analysis, with a P value of < 0.05 considered statistically significant.

RESULTS

miR195, LDH-5, and PTEN expression in CRC tissues

The positive rate of miR195 was 35.85% in CRC tissues, significantly lower than that in adjacent normal tissues (90.57%). LDH-5 had a positive rate of 79.25%, which was remarkably higher than that in adjacent normal tissues (11.32%). PTEN displayed a positive rate of 28.30%, significantly lower than that in adjacent normal tissues (94.34%) (Table 1). Our findings showed that compared with adjacent normal tissues, CRC tissues presented with low miR195 and PTEN expression, as well as high LDH-5 expression, implying significant dysregulation of key biomarkers in CRC tissues compared to adjacent normal mucosa.

Table 1 The microRNA 195, lactate dehydrogenase-5, and phosphatase and tensin homologue expression in colorectal cancer tissues and adjacent normal tissues, n (%).

Group	miR195		LDH-5		PTEN
	Positive	Negative	Positive	Negative	Positive	Negative
CRC tissues (n = 53)	19 (35.85)	34 (64.15)	42 (79.25)	11 (20.75)	15 (28.30)	38 (71.70)
Adjacent normal tissues (n = 53)	48 (90.57)	5 (9.43)	6 (11.32)	47 (88.68)	50 (94.34)	3 (5.66)
χ2	34.116		49.345		48.724
P value	< 0.001		< 0.001		< 0.001

CRC: Colorectal cancer; miR195: MicroRNA 195; LDH-5: Lactate dehydrogenase-5; PTEN: Phosphatase and tensin homologue.

Correlation of miR195, LDH-5, and PTEN with clinicopathological parameters

To further investigate the association between the expression of miR195, LDH-5, and PTEN and the clinicopathological parameters of CRC patients, we analyzed relevant clinical data. The results, as displayed in Table 2, revealed no significant associations between the expression levels of miR195, LDH-5, and PTEN and patients sexes, or ages, or tumor sites. However, miR195 expression was significantly associated with TNM staging and lymph node metastasis (P < 0.05) but not with tumor diameter or differentiation degree (P > 0.05). LDH-5 expression was correlated with TNM stages, differentiation degree, and lymph node metastasis (P < 0.05) but not with tumor diameter (P > 0.05). PTEN expression was related to tumor diameter and lymph node metastasis (P < 0.05) but not to TNM stages or differentiation degree (P > 0.05). Our results denoted that miR195 expression was higher in CRC tissues from patients with earlier TNM stages and no lymph node metastasis. LDH-5 expression was elevated in patients with advanced TNM stages, lower differentiation grades, and the presence of lymph node metastasis. Additionally, PTEN expression was higher in patients with smaller tumor diameters and no lymph node metastasis.

Table 2 Correlation of microRNA 195, lactate dehydrogenase-5, and phosphatase and tensin homologue expression with clinicopathological features, n (%).

Clinical features	Factors	n	miR195		χ2	P value	LDH-5		χ2	P value	PTEN		χ2	P value
			Positive (n = 19)	Negative (n = 34)			Positive (n = 42)	Negative (n = 11)			Positive (n = 15)	Negative (n = 38)
Sex	Male	30	11 (36.67)	19 (63.33)	0.020	0.887	22 (73.33)	8 (26.67)	1.469	0.225	9 (30.00)	21 (70.00)	0.098	0.754
	Female	23	8 (34.78)	15 (65.22)			20 (86.96)	3 (13.04)			6 (26.09)	17 (73.91)
Age, years	≥ 50	24	9 (37.50)	15 (62.50)	0.052	0.820	18 (75.00)	6 (25.00)	0.481	0.488	9 (37.50)	15 (62.50)	1.829	0.176
	< 50	29	10 (34.48)	19 (65.52)			24 (82.76)	5 (17.24)			6 (20.69)	23 (79.31)
Tumor site	Colon	28	12 (42.86)	16 (57.14)	1.268	0.260	21 (75.00)	7 (25.00)	0.651	0.420	7 (25.00)	21 (75.00)	0.319	0.572
	Rectum	25	7 (28.00)	18 (72.00)			21 (84.00)	4 (16.00)			8 (32.00)	17 (68.00)
TNM stage	I–II	21	13 (61.90)	8 (38.10)	10.268	0.001	13 (61.90)	8 (38.10)	6.359	0.012	8 (38.10)	13 (61.90)	1.644	0.200
	III–IV	32	6 (18.75)	26 (81.25)			29 (90.63)	3 (9.38)			7 (21.88)	25 (78.13)
Tumor diameter, cm	≥ 2	23	5 (21.74)	18 (78.26)	3.512	0.061	16 (69.57)	7 (30.43)	2.315	0.128	3 (13.04)	20 (86.96)	4.662	0.031
	< 2	30	14 (46.67)	16 (53.33)			26 (86.67)	4 (13.33)			12 (40.00)	18 (60.00)
Differentiation degree	Well and moderately	36	16 (44.44)	20 (55.56)	3.601	0.058	25 (69.44)	11 (30.56)	6.555	0.010	12 (33.33)	24 (66.67)	1.400	0.237
	Poorly	17	3 (17.65)	14 (82.35)			17 (100.00)	0 (0)			3 (17.65)	14 (82.35)
Lymph node metastasis	Presence	29	5 (17.24)	24 (82.76)	9.642	0.002	27 (93.10)	2 (6.90)	7.478	0.006	4 (13.79)	25 (86.21)	6.644	0.010
	Absence	24	14 (58.33)	10 (41.67)			15 (62.50)	9 (37.50)			11 (45.83)	13 (54.17)

miR195: MicroRNA 195; LDH-5: Lactate dehydrogenase-5; PTEN: Phosphatase and tensin homologue; TNM: Tumor, node, metastasis.

Relationship among miR195, LDH-5, and PTEN in CRC tissues

Pearson correlation analysis was conducted for analyzing the relationship among miR195, LDH-5, and PTEN in CRC tissues. miR195 was negatively associated with LDH-5 (r = -0.883, P = 0.015) but was positively associated with PTEN (r = 0.429, P = 0.006). LDH-5 had a negative correlation with PTEN (r = -0.396, P < 0.001; Table 3). These results demonstrated that higher expression of miR195 in CRC tissues was associated with lower expression of LDH-5 and higher expression of PTEN.

Table 3 Relationship among microRNA 195, lactate dehydrogenase-5, and phosphatase and tensin homologue in colorectal cancer tissues.

Indicator	miR195		LDH-5
	r	P value	r	P value
miR195	-	-	-0.883	0.015
LDH-5	-0.883	0.015	-	-
PTEN	0.429	0.006	-0.396	< 0.001

miR195: MicroRNA 195; LDH-5: Lactate dehydrogenase-5; PTEN: Phosphatase and tensin homologue.

Correlation of miR195, LDH-5, and PTEN with patient prognosis

The median time to progression (TTP) for miR195-positive patients was 25.50 months, compared with 20.49 months for miR195-negative patients (P = 0.0225). For LDH-5-positive patients, the median TTP was 17.22 months, while for LDH-5-negative patients, it was 22.73 months (P = 0.0299). Similarly, the median TTP for PTEN-positive patients was 25.51 months, compared with 21.69 months for PTEN-negative patients (P = 0.0293), as illustrated in Figure 1. Our findings suggested that CRC patients with positive miR195 expression, negative LDH-5 expression, and positive PTEN expression exhibited a more favorable prognosis.

Figure 1 Correlation of microRNA 195, lactate dehydrogenase-5, and phosphatase and tensin homologue with patient prognosis. A: MicroRNA 195; B: Phosphatase and tensin homologue; C: Lactate dehydrogenase-5. miR195: MicroRNA 195; PTEN: Phosphatase and tensin homologue; LDH-5: Lactate dehydrogenase-5; TTP: The median time to progression.

DISCUSSION

CRC is one of the most highly malignant gastrointestinal tumors with a significant incidence and mortality rate at present[18], posing a serious threat to public health. Surgical resection remains the primary curative approach for treating CRC currently. However, clinical outcomes are frequently compromised by late-stage presentation, with the majority of patients diagnosed at advanced stage when surgical efficacy is markedly diminished. Moreover, postoperative recurrence and metastasis contributes to the characteristically poor prognosis observed in CRC patients[19]. Therefore, it is of great significance to investigate the mechanisms underlying CRC metastasis and recurrence, identify novel molecular markers, and elucidate their relationships with clinicopathological features for improved survival of CRC patients.

Recent advances in miRNA research have significantly expanded our understanding of CRC biology, revealing the critical involvement of numerous miRNAs including miR-21, miR-142-3p, and miR-506-3p in disease development and progression[20,21]. These small regulatory molecules exert their effects through complex networks, modulating downstream targets and signaling pathways that govern key oncogenic processes such as tumor growth, invasion, and metastasis[22-24]. Among these, miR195, a member of the miR-15a and miR-16-1 family, is one of the earliest identified tumor-associated miRNAs. Its cell type-specific expression patterns, and abnormal expression have been implicated in various pathological processes and prognosis[25]. LDH-5, a key enzyme in glycolysis, is significantly elevated in tissues of lung cancer, renal cancer, oral cancer, breast cancer, and CRC[26]. PTEN, a tumor suppressor gene discovered after p53, possesses dual phosphatase activity targeting both proteins and lipids, with its functional loss strongly associated with cancer initiation and progression[27]. In our study, we compared the expression levels of miR195, LDH-5, and PTEN in tumor tissues and adjacent normal tissues from 53 CRC patients. In contrast with normal tissues, tumor tissues exhibited downregulated miR195 expression, upregulated LDH-5 expression, and downregulated PTEN expression. This triad of alterations suggests that miR195 and PTEN loss and abnormal high expression of LDH-5 may dampen normal cell growth and adhesion, promote tumor angiogenesis, and facilitate the development of CRC. Miyazaki et al[28] analyzed the results of four miRNA groups in 200 high-risk T1-stage CRC patients from two independent cohorts. Their findings identified miR195 as a promising liquid biopsy marker for identifying high-risk T1-stage CRC patients, potentially preventing overtreatment through improved preoperative risk stratification. Lin et al[29] reported that circular RNA TATDN3 (circTATDN3) upregulated LDHA expression by adsorbing and boosting miR-511-5p, synergistically contributing to CRC progression. High LDHA expression dramatically promoted the development and progression of CRC. Additionally, some researchers have unraveled that the loss of the tumor suppressor PTEN is a critical event in CRC progression. Bromodomain and extra-terminal domain heightens the overall level of p21 by suppressing myelocytomatosis viral oncogene homolog and promotes the nuclear import of p21 by dampening the PI3K/AKT upstream pathway, ultimately inducing selective G1 phase arrest and apoptosis in PTEN-deficient cells, demonstrating the crucial role of PTEN as a tumor suppressor gene in CRC[30]. These studies align closely with the conclusions of our research.

To elucidate the clinical relevance of miR-195, LDH-5, and PTEN in colorectal carcinogenesis, we conducted a comprehensive correlation analyses between their expression patterns and clinicopathological parameters. The results revealed that factors such as age, sex, and tumor sites displayed no significant correlation with miR195, LDH-5, and PTEN expression. However, distinct associations were observed among patients with different TNM stages, differentiation degrees, tumor diameters, and lymph node metastasis status. miR-195 positivity correlated strongly with early-stage disease (TNM I-II) and absence of lymph node metastasis, while those with LDH-5 positivity were more likely to have advanced TNM stages and lymph node metastasis. Patients with PTEN positivity were more likely to have smaller tumor diameters and no lymph node metastasis. These data suggested that miR195 and PTEM loss and overexpression of LDH-5 are inextricably linked to the malignant transformation and progression of CRC. The identified expression signature offers a promising molecular biomarkers for the clinicopathological biopsy diagnosis, prognosis assessment, and prediction of tumor biological behaviors in CRC, holding significant implications for guiding clinical gene and protein-based therapies. Furthermore, our interaction analysis uncovered significant inter-molecular relationships. The results revealed a negative correlation between miR195 and LDH-5, a positive relationship between miR195 and PTEN, and a negative correlation between LDH-5 and PTEN, demonstrating potential crosstalk within this molecular network.

Our longitudinal survival analysis over a 3-year period revealed significant associations between biomarker expression profiles and clinical outcomes in CRC patients. Patients with elevated miR195 and PTEN expression, along with reduced LDH-5 levels, exhibited longer median survival and improved clinical outcomes. These findings are consistent with those reported by Mirzapour Abbas Abadi et al[31]. Given that tumor aggressiveness directly correlates with invasive potential and metastatic propensity. Surgical treatment often fails to completely remove the lesions, and recurrence is highly common[32,33]. Such clinical challenges underscore the critical need for biomarkers capable of predicting tumor behavior and guiding therapeutic strategies. Low miR195 and PTEN levels, along with high LDH-5 expression, may promote the proliferation and microvascular formation of tumor cells, accelerating tumor invasion and metastasis, hence impacting patient survival outcomes.

Current diagnostic paradigm for CRC incorporated two established approaches: Carcinoembryonic antigen (CEA) test and microsatellite instability (MSI) analysis. While CEA can assist in the initial diagnosis of CRC by detecting its level in the blood and help determine whether the tumor has progressed or metastasized. On the other hand, MSI testing can effectively identify Lynch syndrome-related CRC and evaluate the mismatch repair function of tumors. The two have different but complementary and significant values in the diagnosis of CRC. Notably, although CEA is a commonly used tumor marker, its specificity is not strong, and it may also increase in some non - tumor diseases. Our findings suggest that incorporating miR195, LDH-5, and PTEN evaluation into routine diagnostic workflows could significantly enhance clinical decision-making. That is, detecting multiple indicators simultaneously can complement each other and improve the accuracy of diagnosis.

However, this study has some limitations. Our study is a single-center, small-sample, retrospective study, which may introduce certain biases into the results. Further studies are required to increase the sample size and perform multi-center, prospective studies to validate our findings. Additionally, further in-depth mechanistic explorations will be undertaken.

CONCLUSION

To conclude, our study demonstrates a distinct molecular signature in CRC, characterized by downregulation of miR195 and PTEN alongside upregulation of LDH-5, which correlates significantly with TNM staging, differentiation, tumor diameters, as well as lymph node metastasis in patients. These findings imply that miR195, LDH-5, and PTEN, plays a crucial role in CRC development and progression, offering the potential biomarkers that may improve CRC management and outcomes. However, our article also has limitations. In this study, we did not explore the regulatory relationships among miR195, LDH-5, and PTEN. In future research, we will design a series of experiments to thoroughly investigate the specific molecular mechanisms by which miR195 regulates LDH-5 and PTEN, and clarify the specific signaling pathways involved in the regulatory role of miR195.