Metformin suppresses hypoxia‑induced migration via the HIF‑1α/VEGF pathway in gallbladder cancer in�vitro and in�vivo

Abstract

Hypoxia plays a crucial role in cancer development and progression. Overexpression of hypoxia-inducible factor-1α (HIF-1α) has been demonstrated in a hypoxic microenvironment in various tumor types. Metformin has been identified as an antitumor drug in various tumor types. However, its role in cellular migration in a hypoxic microenvironment, and the associated regulatory mechanism, have yet to be fully elucidated. The present study aimed to investigate the clinical significance of HIF-1α, and its biological role, in gallbladder cancer (GBC). Furthermore, the role of metformin in cellular migration, and its underlying mechanism in GBC, were also identified. Real-time quantitative polymerase chain reaction analysis and immunohistochemistry experiments revealed that HIF-1α was significantly upregulated in GBC tissues. HIF-1α overexpression was closely associated with lymph node metastasis and tumor-lymph node-metastasis (TNM) stages. HIF-1α was able to promote cell migration in a hypoxic microenvironment by overexpressing vascular endothelial growth factor (VEGF) in GBC-SD cells, an effect which was partly reversed by small-interfering RNA HIF-1α (siHIF-1α) and 2-methoxyestradiol. Further experiments demonstrated that metformin inhibited hypoxia-induced migration via HIF-1α/VEGF in vitro. In addition, metformin suppressed GBC growth and downregulated the expression of HIF-1α and VEGF in a GBC-SD cell xenograft model. Taken together, these results suggest that HIF-1α may contribute to tumor migration via the overexpression of VEGF in GBC, while metformin is able to inhibit tumor migration by targeting the HIF-1α/VEGF pathway.

Metformin induces TPC-1 cell apoptosis through endoplasmic reticulum stress-associated pathways in vitro and in vivo

“…In the present study, the anticancer effect of metformin was explored in thyroid cancer cells, instead of a diabetic model. Our previous study also indicated that metformin at 20 mM exhibits anticancer effects in gallbladder cancer (18). Similar in vitro concentrations have been used in other studies (16,30,31).…”

“…Tumor xenografts were established by subcutaneous inoculation into the right flank of nude mice. The mice were randomly divided into two groups of 5 mice: the control group, administered with PBS containing 10% DMSO; and the metformin group, administered with 350 mg/kg intragastric metformin infusion, daily (16)(17)(18). The volume of the tumors was measured using calipers every week.…”

Mitochondrial Dysfunction Inhibits Hypoxia-Induced HIF-1α Stabilization and Expression of Its Downstream Targets

“…The CI inhibitor AG311 also reduced HIF-1α stabilization and in combination with an inhibitor of the pyruvate dehydrogenase kinase, a key regulatory enzyme of oxidative metabolism, resulted in a reduced tumor growth (54). The potentially most clinical interesting CI inhibitor, metformin, also used in our study, has already shown its ability to decrease HIF-1α stabilization in various tumor backgrounds (55,56) and therefore contributes to a slower tumor growth, potentially related to the suppression of VEGF (56)(57)(58). However, a tumor-dependent effect might be present as we did not observe reduced levels of CAIX and VEGF upon metformin exposure in all tumor cell types.…”

Targeting Hypoxia Sensitizes TNBC to Cisplatin and Promotes Inhibition of Both Bulk and Cancer Stem Cells

“…To prevent cisplatin-induced hypoxia, we employed metformin (first-line therapy for the treatment of type II diabetes), which was found to potently suppress hypoxia [21,[57][58][59]. Metformin inhibits complex I of the mitochondria to indirectly stimulate AMPK, which, in turn, activates TSC1/TSC2 to inhibit mTORC1 and subsequent hypoxia signalling.…”