Metformin increases natural killer cell functions in head and neck squamous cell carcinoma through CXCL1 inhibition

Abstract

BackgroundMetformin slows tumor growth and progression in vitro, and in combination with chemoradiotherapy, resulted in high overall survival in patients with head and neck cancer squamous cell carcinoma (HNSCC) in our phase 1 clinical trial (NCT02325401). Metformin is also postulated to activate an antitumor immune response. Here, we investigate immunologic effects of metformin on natural killer (NK) and natural killer T cells, including results from two phase I open-label studies in patients with HNSCC treated with metformin (NCT02325401,NCT02083692).MethodsPeripheral blood was collected before and after metformin treatment or from newly diagnosed patients with HNSCC. Peripheral immune cell phenotypes were evaluated using flow cytometry, cytokine expression by ELISA and/or IsoLight, and NK cell-mediated cytotoxicity was determined with a flow-based NK cell cytotoxicity assay (NKCA). Patient tumor immune infiltration before and after metformin treatment was analyzed with immunofluorescence. NK cells were treated with either vehicle or metformin and analyzed by RNA sequencing (RNA-seq). NK cells were then treated with inhibitors of significant pathways determined by RNA-seq and analyzed by NKCA, ELISA, and western blot analyses.ResultsIncreased peripheral NK cell activated populations were observed in patients treated with metformin. NK cell tumor infiltration was enhanced in patients with HNSCC treated with metformin preoperatively. Metformin increased antitumorigenic cytokines ex vivo, including significant increases in perforin. Metformin increased HNSCC NK cell cytotoxicity and inhibited the CXCL1 pathway while stimulating the STAT1 pathway within HNSCC NK cells. Exogenous CXCL1 prevented metformin-enhanced NK cell-mediated cytotoxicity. Metformin-mediated NK cell cytotoxicity was found to be AMP-activated protein kinase independent, but dependent on both mechanistic target of rapamycin and pSTAT1.ConclusionsOur data identifies a new role for metformin-mediated immune antitumorigenic function through NK cell-mediated cytotoxicity and downregulation of CXCL1 in HNSCC. These findings will inform future immunomodulating therapies in HNSCC.

Metformin: update on mechanisms of action and repurposing potential

“…Metformin treatment also increased natural killer cell infiltration and cytotoxicity in head and neck squamous cell carcinoma in patients by promoting perforin release secondary to an AMPK-independent and mTORC1–STAT1-mediated downregulation of CXCL1 (ref. 183 ) (Fig. 2b ).…”

Metformin and chidamide synergistically suppress multiple myeloma progression and enhance lenalidomide/bortezomib sensitivity

“…Metformin shows anticancer activities in various malignancies, including colorectal cancer, thyroid cancer along with head and neck cancer. [31][32][33] A study has also revealed that type II diabetes patients who received metformin treatment have an obviously lower risk of MM. 34 Chidamide is a new oral benzamide-type selective HDAC inhibitor with anticancer activity in multiple cancers, such as hematologic cancer, lung carcinoma, and laryngeal carcinoma.…”

“…Metformin shows anticancer activities in various malignancies, including colorectal cancer, thyroid cancer along with head and neck cancer 31–33 . A study has also revealed that type II diabetes patients who received metformin treatment have an obviously lower risk of MM 34 .…”

Advancements in Cancer Immunotherapies

“…has shown that the antidiabetic agent metformin slows tumor growth and progression in vitro and in combination with chemoradiotherapy in patients suffering from head and neck cancer squamous cell carcinoma (HNSCC) in their phase 1 clinical trial (NCT02325401). It increases the activated peripheral NK cell populations, enhanced HNSCC NK cell cytotoxicity, and inhibited the CXCL1 pathway while stimulating the STAT1 pathway [ 52 ]. It also influences anticancer immunity in esophageal squamous cell carcinoma (ESCC) in both humans and mice, via triggering an AMPK activation and STAT3 inactivation.…”