Metformin reverses mesenchymal phenotype of primary breast cancer cells through STAT3/NF-κB pathways

Abstract

Background Breast cancer currently is the most frequently diagnosed neoplasm and the leading cause of death from cancer in women worldwide, which is mainly due to metastatic disease. Increasing our understanding of the molecular mechanisms leading to metastasis might thus improve the pharmacological management of the disease. Epithelial-mesenchymal transition (EMT) is a key factor that plays a major role in tumor metastasis. Some pro-inflammatory cytokines, like IL-6, have been shown to stimulate phenotypes consistent with EMT in transformed epithelial cells as well as in carcinoma cell lines. Since the EMT is one of the crucial steps for metastasis, we studied the effects of metformin (MTF) on EMT. Methods Cytotoxic effect of MTF was evaluated in eight primary breast cancer cell cultures by crystal violet assay. EMT markers and downstream signaling molecules were measured by Western blot. The effect of MTF on cell proliferation and cell migration were analyzed by MTT and Boyden chamber assays respectively. Results We observed that the response of cultured breast cancer primary cells to MTF varied; mesenchymal cells were resistant to 10 mM MTF and expressed Vimentin and SNAIL, which are associated with a mesenchymal phenotype, whereas epithelial cells were sensitive to this MTF dose, and expressed E-cadherin but not mesenchymal markers. Further, exposure of mesenchymal cells to MTF down-regulated both Vimentin and SNAIL as well as cell proliferation, but not cell migration. In an in vitro IL-6-induced EMT assay, primary breast cancer cells showing an epithelial phenotype underwent EMT upon exposure to IL-6, with concomitant activation of STAT3 and NF-κB; addition of MTF to IL-6-induced EMT reversed the expression of the mesenchymal markers Vimentin and SNAIL, decreased pSTAT3 Y705 and pNF-κB S536 and increased E-cadherin. In addition, downregulation of STAT3·activation was dependent on AMPK, but not NF-κB phosphorylation. Further, MTF inhibited cell proliferation and migration stimulated by IL-6. Conclusion These results suggest that MTF inhibits IL-6-induced EMT, cell proliferation, and migration of primary breast cancer cells by preventing the activation of STAT3 and NF-κB. STAT3 inactivation occurs through AMPK, but not NF-κB. Electronic supplementary material The online version of this article (10.1186/s12885-019-5945-1) contains supplementary material, which is available to authorized users.

Anti-Aging Effects of Calorie Restriction (CR) and CR Mimetics Based on the Senoinflammation Concept

“…Chronic transactivation of NF-κB has been observed in multiple tissues in various experimental models of aging and human fibroblasts and human CD4+ T cells obtained from aged individuals [25,26]. NF-κB induces proinflammatory mediators, chemokines, and adhesion molecules [27] and interacts with other transcriptional factors that are involved in the initiation and deterioration of chronic inflammatory response including signal transducers, the activator of transcription 3 (STAT3) and p53 [22]. The transcriptional activity of NF-κB occurs concurrently with crosstalk among upstream signaling components such as glycogen synthase kinase 3 (GSK3)-β, mitogen-activated protein kinase (MAPK), mammalian target of rapamycin (mTOR), and protein kinase B (PKB) [23,28].…”

Metformin alleviates breast cancer through targeting high‐mobility group AT‐hook 2

“…There exists a close correlation among metformin treatment and cancer incidence or patient survival . For the molecular mechanism of metformin in cancer treatment, it has been reported to inactivate STAT3 or NF‐κB, preventing IL‐6‐induced breast cancer progression . In prostate cancer, lung cancer, colon cancer or breast cancer patients with T2DM, metformin has been shown to reduce the development of tumor and prolong the survival .…”

“…[4][5][6] For the molecular mechanism of metformin in cancer treatment, it has been reported to inactivate STAT3 or NF-κB, preventing IL-6-induced breast cancer progression. 7 In prostate cancer, lung cancer, colon cancer or breast cancer patients with T2DM, metformin has been shown to reduce the development of tumor and prolong the survival. 8,9 Metformin together with phenformin also resists the development of colon cancer through promoting AMPK and ROS production and inhibiting glycolysis.…”

“…An increasing number of studies display the relationship among metformin treatment and cancer incidence or patient survival . Metformin is able to inactivate STAT3 and NF‐κB to suppress IL‐6‐induced breast cancer progression . Some researchers have observed that metformin can reduce the development of tumor and prolong the survival of patients with T2DM and different cancers, such as prostate cancer, lung cancer, colon cancer or breast cancer .…”

“…[4][5][6] Metformin is able to inactivate STAT3 and NF-κB to suppress IL-6-induced breast cancer progression. 7 Some researchers have observed that metformin can reduce the development of tumor and prolong the survival of patients with T2DM and different cancers, such as prostate cancer, lung cancer, colon cancer or breast cancer. 8,9 In certain types of cancer including melanoma, ovarian, prostate, lung, colon or breast cancers, metformin and phenformin have been shown to prevent tumor progression.…”