Metformin combined with aspirin significantly inhibit pancreatic cancer cell growthin vitroandin vivoby suppressing anti-apoptotic proteins Mcl-1 and Bcl-2

Abstract

Metformin and aspirin have been studied extensively as cancer preventive or therapeutic agents. However, the effects of their combination on pancreatic cancer cells have not been investigated. Herein, we evaluated the effects of metformin and aspirin, alone or in combination, on cell viability, migration, and apoptosis as well as the molecular changes in mTOR, STAT3 and apoptotic signaling pathways in PANC-1 and BxPC3 cells. Metformin and aspirin, at relatively low concentrations, demonstrated synergistically inhibitory effects on cell viability. Compared to the untreated control or individual drug, the combination of metformin and aspirin significantly inhibited cell migration and colony formation of both PANC-1 and BxPC-3 cells. Metformin combined with aspirin significantly inhibited the phosphorylation of mTOR and STAT3, and induced apoptosis as measured by caspase-3 and PARP cleavage. Remarkably, metformin combined with aspirin significantly downregulated the anti-apoptotic proteins Mcl-1 and Bcl-2, and upregulated the pro-apoptotic proteins Bim and Puma, as well as interrupted their interactions. The downregulation of Mcl-1 and Bcl-2 was independent of AMPK or STAT3 pathway but partially through mTOR signaling and proteasome degradation. In a PANC-1 xenograft mouse model, we demonstrated that the combination of metformin and aspirin significantly inhibited tumor growth and downregulated the protein expression of Mcl-1 and Bcl-2 in tumors. Taken together, the combination of metformin and aspirin significantly inhibited pancreatic cancer cell growth in vitro and in vivo by regulating the pro- and anti-apoptotic Bcl-2 family members, supporting the continued investigation of this two drug combination as chemopreventive or chemotherapeutic agents for pancreatic cancer.

Proteomic modulation in breast tumors after metformin exposure: results from a “window of opportunity” trial

“…Bad, or the Bcl-2 associated death promoter, is a member of the pro-apoptotic Bcl-2 family, which also includes Bim, Bax, and Bid. Other studies demonstrated either no change in Bad levels (pancreatic cell lines, PANC-1 and BxPC3) [35] or an increase in Bad expression (ovarian epithelial cell lines, OVCAR-3, and OVCAR-4) [36] after metformin. In addition, we identified changes in cell-cycle markers that differ from the description of others.…”

Metformin synergizes with rapamycin to inhibit the growth of pancreatic cancer in�vitro and in�vivo

“…A previous study reported that metformin combined with vemurafenib may induce apoptosis and result in the synergistic inhibition of the growth of cancer cells, suggesting that metformin reverses the resistance of cancer cells to vemurafenib by altering the cellular energy balance (24). Metformin and salicylate may synergistically reduce the survival of cancer cells in vitro by inhibiting de novo lipogenesis and targeting pro-apoptotic and Bcl-2 family members (25,26). Metformin also synergizes with chemotherapy to reverse multi-drug resistance in cancers by targeting the AMPK/mTOR/hypoxia inducible factor-1α/P-glycoprotein/multidrug resistance-associated protein 1 signaling pathway (27,28).…”

Aspirin and metformin exhibit antitumor activity in murine breast cancer

“…Not surprisingly, metformin and aspirin have synergistic effects and share several underlying mechanisms for controlling cancer (24)(25)(26). In the present study, we investigated the antitumor activity of aspirin and metformin mediated by the TGF-β signaling pathway.…”