Host and gut microbiota crosstalk: A new paradigm for colorectal cancer immunotherapy

Table 1 Effect of pathogenic bacteria on colorectal cancer tumorigenesis

CRC-associated bacteria	Virulence factors	Proposed carcinogenic mechanisms	Ref.
Fn	Fap2	Inhibited natural killer cell cytotoxicity and tumor-infiltrating lymphocyte activities	[76]
	FadA, Fap2, RadD, and FomA	Increased bacterial biomass and acute inflammation with pro-tumorigenic potential, tumor-associated macrophage type 2 and regulatory T cell infiltration in the tumor	[75]
	Formate	T helper 17 cell-favored proinflammatory profiles and metabolic shift with CRC stemness, invasion and metastasis	[77]
CoPEC	Colibactin	Impaired antitumor T-cell response and procarcinogenic TME leading to immunotherapy resistance	[79]
		Oncogenic-driven lipid reprogramming for lower tumor immunogenicity and acquired chemoresistance	[80]
ETBF	BFT	A pro-carcinogenic multi-step inflammatory cascade and nuclear factor-κB-activated myeloid-cell-dependent neoplasia	[63]
NTS	AvrA, SopE, SopE2, SopB, and SptP	Oncogenic transformation of pre-transformed cells upon targeting the host’s β-catenin, MAPK, and AKT signaling pathways	[81]
	Bacterial invasion and intracellular replication	Host cell metabolic transformation associated with high mammalian target of rapamycin activation	[82]

CRC: Colorectal cancer; TME: Tumor microenvironment; MAPK: Mitogen-activated protein kinase; AKT: Protein kinase B; Fn: Fusobacterium nucleatum; CoPEC: Colibactin-producing Escherichia coli; ETBF: Enterotoxigenic Bacteroides fragilis; NTS: Nontyphoidal Salmonella; Fap2: Fusobacterium autotransporter protein 2; FadA: Fusobacterium adhesin A; RadD: Radiation-sensitive DNA adhesins; FomA: Fusobacterial outer membrane protein A; BFT: Bacteroides fragilis toxin; AvrA: Anti virulence agent A; SopE: Salmonella outer protein E; SopB: Salmonella outer protein B; SptP: Salmonella protein tyrosine phosphatase.