Connexins (Cx) play both gap junctionrelated and independent roles in cells, and their localization is essential for their function in cellular processes. Besides membrane localization, connexins can also be localized to the cytoplasm and nucleus, especially in cancer cells. The differential localization of connexins including Cx32 was observed in different stages of cancers. Cx32 was upregulated and observed in cytoplasms of cells in lymphnode metastasis of breast cancer samples compared to primary tumors. However, the significance of the increase in Cx32 expression and alteration of Cx32 cellular localization in epithelialtomesenchymal transition (EMT) is not known. To determine if Cx32 overexpression and/or localization over one week would induce the EMT process we first examined the cellular localization of Cx32 in MCF10A and MDAMB231 cells at different time points using Western blot and RTPCR as well as immunostaining with confocal microscopy. Then, we correlated the changes of Cx32 expression and localization with EMT marker expression. We showed that Cx32 had altered cellular localization and Cx32 overexpression increased Slug levels while it reduced Ecadherin and Snail expression in MDAMB231 for 7 days. In contrast, Ecadherin and Vimentin were reduced in MCF10ACx32 cells compared with controls over 7 days, and the expression pattern for nuclear Cx32 and Zeb2 was following similar pattern in MCF10A cells. Our results suggest a previously unknown timedependent relation between Cx32 and the regulation of the EMT process.
Keywords: breast cancer; connexin32; epithelialtomesenchymal transition; nucleus; localization
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References
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