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Increased TMEM16A channel activities activate EGFR/STAT3/ROCK1 signaling, and ROCK1 activation by RhoA increased TMEM16A channel activities via moesin phosphorylation at T558. TMEM16A and ROCK1/moesin signaling cooperatively promotes breast cancer metastasis. [Display omitted] Transmembrane protein 16A (TMEM16A) is a Ca2+-activated chloride channel that plays a role in cancer cell proliferation, migration, invasion, and metastasis. However, whether TMEM16A contributes to breast cancer metastasis remains unknown. In this study, we investigated whether TMEM16A channel activation by ROCK1/moesin promotes breast cancer metastasis. Wound healing assays and transwell migration and invasion assays were performed to study the migration and invasion of MCF-7 and T47D breast cancer cells. Western blotting was performed to evaluate the protein expression, and whole-cell patch clamp recordings were used to record TMEM16A Cl− currents. A mouse model of breast cancer lung metastasis was generated by injecting MCF-7 cells via the tail vein. Metastatic nodules in the lung were assessed by hematoxylin and eosin staining. Lymph node metastasis, overall survival, and metastasis-free survival of breast cancer patients were assessed using immunohistochemistry and The Cancer Genome Atlas dataset. TMEM16A activation promoted breast cancer cell migration and invasion in vitro as well as breast cancer metastasis in mice. Patients with breast cancer who had higher TMEM16A levels showed greater lymph node metastasis and shorter survival. Mechanistically, TMEM16A promoted migration and invasion by activating EGFR/STAT3/ROCK1 signaling, and the role of the TMEM16A channel activity was important in this respect. ROCK1 activation by RhoA enhanced the TMEM16A channel activity via the phosphorylation of moesin at T558. The cooperative action of TMEM16A and ROCK1 was supported through clinical findings indicating that breast cancer patients with high levels of TMEM16A/ROCK1 expression showed greater lymph node metastasis and poor survival. Our findings revealed a novel mechanism underlying TMEM16A-mediated breast cancer metastasis, in which ROCK1 increased TMEM16A channel activity via moesin phosphorylation and the increase in TMEM16A channel activities promoted cell migration and invasion. TMEM16A inhibition may be a novel strategy for treating breast cancer metastasis. [ABSTRACT FROM AUTHOR]

Background and Purpose: Ca2+‐activated Cl− channels (Ano1 channels) contribute to the pathogenesis of colorectal cancer. Honokiol is known to inhibit cell proliferation and tumour growth in colorectal cancer. However, the molecular target of honokiol remains unclear. This study aimed to investigate whether honokiol inhibited cell proliferation of colorectal cancer by targeting Ano1 channels. Experimental Approach Patch‐clamp techniques were performed to study the effect of honokiol on Ca2+‐activated Cl− currents in HEK293 cells overexpressing Ano1‐ or Ano2‐containing plasmids or in human colorectal carcinoma SW620 cells. Site‐directed mutagenesis was used to identify the critical residues for honokiol‐induced Ano1 inhibition. Proliferation of SW620 cells or human intestinal epithelial NCM460 cells by CCK‐8 assays. Key Results: Honokiol blocked Ano1 currents in Ano1‐overexpressing HEK293 cells and SW620 cells. Honokiol more potently inhibited Ano1 currents than Ano2 currents. Three amino acids (R429, K430 and N435) were critical for honokiol‐induced Ano1 inhibition. The R429A/K430L/N435G mutation reduced the sensitivity of Ano1 to honokiol. Honokiol inhibited SW620 cell proliferation, and this effect was reduced by Ano1‐shRNAs. Furthermore, Ano1 overexpression promoted proliferation in NCM460 cells with low Ano1 endogenous expression and resulted in an increased sensitivity to honokiol. Overexpression of the R429A/K430L/N435G mutation reduced WT Ano1‐induced increase in the sensitivity of NCM460 cells to honokiol. Conclusion and Implications: We identified a new anticancer mechanism of honokiol, through the inhibition of cell proliferation, by targeting Ano1 Ca2+‐activated Cl− channels. [ABSTRACT FROM AUTHOR]

A positive activation loop between TMEM16A and the IP 3 R/Ca2+/NFκB/IL-6 pathway is important for Ca2+ elevation, NFκB activation and IL-6 release, and thus cooperatively promotes the pathogenesis of AP. TMEM16A Ca2+-activated Cl− channels are expressed in pancreatic acinar cells and participate in inflammation-associated diseases. Whether TMEM16A contributes to the pathogenesis of acute pancreatitis (AP) remains unknown. Here, we found that increased TMEM16A expression in the pancreatic tissue was correlated with the interleukin-6 (IL-6) level in the pancreatic tissue and in the serum of a cerulein-induced AP mouse model. IL-6 treatment promoted TMEM16A expression in AR42J pancreatic acinar cells via the IL-6 receptor (IL-6R)/signal transducers and activators of transcription 3 (STAT3) signaling pathway. In addition, TMEM16A was co-immunoprecipitated with the inositol 1,4,5-trisphosphate receptor (IP 3 R) and was activated by IP 3 R-mediated Ca2+ release. TMEM16A inhibition reduced the IP 3 R-mediated Ca2+ release induced by cerulein. Furthermore, TMEM16A overexpression activated nuclear factor-κB (NFκB) and increased IL-6 release by increasing intracellular Ca2+. TMEM16A knockdown by shRNAs reduced the cerulein-induced NFκB activation by Ca2+. TMEM16A inhibitors inhibited NFκB activation by decreasing channel activity and reducing TMEM16A protein levels in AR42J cells, and it ameliorated pancreatic damage in cerulein-induced AP mice. This study identifies a novel mechanism underlying the pathogenesis of AP by which IL-6 promotes TMEM16A expression via IL-6R/STAT3 signaling activation, and TMEM16A overexpression increases IL-6 secretion via IP 3 R/Ca2+/NFκB signaling activation in pancreatic acinar cells. TMEM16A inhibition may be a new potential strategy for treating AP. [ABSTRACT FROM AUTHOR]