Table 2 The summary of preclinical (in vivo) use of metformin in CRC models

HT-29-xenografted BALB/c-nude mice

Co-administration of metformin (250 mg/kg) with sirolimus (1 mg/kg), tacrolimus (1 mg/kg) or cyclosporin A (5 mg/kg) for four weeks significantly suppresses the tumor growth in HT-29-xenografted BALB/c-nude mice by downregulating the expression of p-mTOR, p-70S6K, p-4EBP1, livin, survivin, E-cadherin, TGF-β, and pSmad3.

Apc mutated mice

Metformin (250 mg/kg/day, 10 weeks) reduces polyps number (2.0–2.5 mm) but increases polyps ranging from 1.0–1.5 mm in diameter in Apc^Min/+ mice. No significant reduction in total number of polyps in the small intestine and changes in BrdU index, PCNA index, percentage of apoptotic cells, cyclin D1 and c-myc as compared to untreated group.

Metformin (250 mg/kg/day, 6–32 weeks) + basal diet inhibit formation of ACF in azoxymethane-induced mice. Treatment decreased total number of polyp formation (by 20%), polyp expansion (by 11%) and abolished polyps larger than 3 mm. Metformin suppressed the colonic epithelial cell proliferation (not by apoptosis) in the azoxymethane-induced mice.

MC38-xenografts mice

Metformin mitigates high-energy diet-induced tumor growth in MC38-xenografts mice by reducing FASN expression.

Organoid peritoneal metastases of CRC patients xenografts

Metformin inhibits DMH-induced ACF formation in diabetic Sprague Dawley rats by reversing the Warburg effect.

COLO25 and DSS-mice

Metformin significantly suppressed TNF-α-stimulated COLO 205 cells and ameliorated DSS-induced acute colitis and colitic cancer in IL-10⁻/⁻ mice.

SW48-Mut xenograft nude mice

Pre-administration of metformin (one week) reduces tumor volume in a time-dependent manner (maximum inhibition ~ 50%) in SW48-Mut xenograft nude mice.

HCT116 and HT-29-xenograft SCID mice

FuOx mixture (metformin (5 weeks) + 5-FU (IP, 25 mg/kg, once a week for 3 weeks) and oxaliplatin (IP, 2 mg/kg, once a week for 3 weeks)) inhibited tumor volume (50%, day 34) in HCT116-xenografts and in HT-29-xenografts (more than 70%). FuOx downregulated CD44, upregulated CK20, and reduced number of stem/stem like cells

Metformin (IP, 250 mg/kg/day) prior to IR inhibits 59% tumor growth as compared to 4.5% in metformin-treated only and IR-treated only HCT116 p53⁻/⁻ xenografts mice. Combination with IR inhibits DNA repair protein that increases radiosensitivity in HCT116 p53⁻/⁻ xenografts mice.

Metformin (alone, 150 mg/kg body weight) and with rapamycin (intraperitoneal, 0.5 mg/kg body weight) modulates AMPK and mTOR modulation, inhibits tumor volume in HCT116-xenorafted NOD/SCIDs male mice. The addition of probiotic mixture inhibited the intracellular ROS, IL-3, and IL-6 levels which further reduced the tumor volume by 40%.

DMH-induced CRC in diabetic and non-diabetic mice

Single (100 or 200 mg/kg) and combination of metformin and/or oxaliplatin inhibited angiogenesis and tumor proliferation in DMH-induced CRC diabetic and non-diabetic mice by suppressing tumor angiogenesis and cell proliferation by reducing serum VEGF level and intratumoral IGFR-I.

PDX- female SCID mice

Metformin (150 mg/kg, 24 days) suppresses tumor growth (by 50%) in PDX CRC-female SCID mice. Combination with 5-FU (IP, 25 mg/kg) inhibited tumor growth (up to 85%). Metformin exposure to ex vivo PDX organoids culture suppresses O₂ via activation of AMPK signaling and inhibited culture growth.

DMH-induced CRC rat and DMH-DSS-induced colitis-associated colon neoplasia mice model

Metformin (medium dose of 120 mg/kg/day) + vitamin D3 (100 IU/kg/day) synergistically enhances the chemopreventive effects against DMH-induced colon cancer rat and DMH-DSS-induced colitis-associated colon neoplasia mice model