Connexin 43 expression is associated with increased malignancy in prostate cancer cell lines and functions to promote migration

Connexin and pannexin channels in cancer

Communication among cells via direct cell-cell contact by connexin gap junctions, or between cell and extracellular environment via pannexin channels or connexin hemichannels, is a key factor in cell function and tissue homeostasis. Upon malignant transformation in different cancer types, the dysregulation of these connexin and pannexin channels and their effect in cellular communication, can either enhance or suppress tumorigenesis and metastasis. In this review, we will highlight the latest reports on the role of the well characterized connexin family and its ability to form gap junctions and hemichannels in cancer. We will also introduce the more recently discovered family of pannexin channels and our current knowledge about their involvement in cancer progression.

Connexin 43 expression is associated with poor survival in patients with esophageal squamous cell carcinoma

Connexin 43 (Cx43) is an important gap junction protein in vertebrates, which has been reported to function as a tumor suppressor in a number of organs. However, the mechanism underlying the effect of Cx43 on tumor progression remains unknown, with only a limited number of studies reporting on the role of Cx43 in esophageal cancer. In the present study, Cx43 expression was analyzed by immunohistochemical staining and the associations between Cx43 expression and clinicopathological characteristics or prognosis were evaluated. Cx43 was expressed at a high frequency in patients with esophageal squamous cell carcinoma (ESCC). Of the 98 ESCC cases investigated, positivity for Cx43 was observed in 62 cases (63.26%). In patients with high Cx43 expression, the survival rates were significantly reduced compared with those in patients with low Cx43 expression. Moreover, the overexpression of Cx43, as measured by immunohistochemistry, was an independent prognostic indicator of ESCC. Thus, our data indicated that Cx43 may be a candidate molecular prognostic marker and molecular target for the development of an effective therapeutic intervention for patients with esophageal cancer.

Translating connexin biology into therapeutics

It is 45 years since gap junctions were first described. Universities face increasing commercial pressures and declining federal funding, with governments and funding foundations showing greater interest in gaining return on their investments. This review outlines approaches taken to translate gap junction research to clinical application and the challenges faced. The need for commercialisation is discussed and key concepts behind research patenting briefly described. Connexin channel roles in disease and injury are also discussed, as is identification of the connexin hemichannel as a therapeutic target which appears to play a role in both the start and perpetuation of the inflammasome pathway. Furthermore connexin hemichannel opening results in vascular dieback in acute injury and chronic disease. Translation to human indications is illustrated from the perspective of one connexin biotechnology company, CoDa Therapeutics, Inc.

Identification of miR-200a as a novel suppressor of connexin 43 in breast cancer cells

We demonstrated that miRNA (miR)-200a inhibited connexin 43 (Cx43) expression by directly targeting at the 3’-UTR of Cx43 gene in human breast cancer cells. The miR-200a/Cx43 axis might be a useful diagnostic and therapeutic target of metastatic breast cancer.

Both miRNAs (miRs) and connexin 43 (Cx43) were important regulators of the metastasis of breast cancer, whereas the miRs regulating Cx43 expression in breast cancer cells were still obscure. In the present study, we scanned and found miR-1, miR-206, miR-200a, miR-381, miR-23a/b and miR-186 were functional suppressors of human Cx43 mRNA and protein expression. Specially, we demonstrated that only miR-200a could directly target the 3′-untranslated region (3′-UTR) of human Cx43 gene. Functionally, overexpression of Cx43 in MCF cells potentiated the migration activity, whereas additional miR-200a treatment notably prevented this effect. Finally, we demonstrated that decreased levels of miR-200a and elevated expression of Cx43 in the metastatic breast cancer tissues compared with the primary ones. Thus, we are the first to identify miR-200a as a novel and direct suppressor of human Cx43, indicating that miR200a/Cx43 axis might be a useful diagnostic and therapeutic target of metastatic breast cancer.

ZO-1 expression shows prognostic value in chronic B cell leukemia

Connexin-mediated gap junctions are vital for tumor cell function. Intracellular pathways of connexin signaling use Zonula Occludens protein-1 (ZO-1) as an intermediate. This report describes the ZO-1 and connexin 43 (Cx43) expression pattern in lymphocytes from chronic B-cell leukemia (B-CLL) patients. The ZO-1 and Cx43 expression in the B cells of 113 B-CLL patients was identified. Western blot and flow cytometry were used to determine protein expression. Results indicated that ZO-1 and Cx43 expression was reduced and correlated negatively with CD38 and Zap-70 expression. Inhibition of intercellular communication with anti-Cx43 antibodies, 1-octanol, or carbenoxolone resulted in induced cell apoptosis. These data suggest that ZO-1, along with CD38 and Zap-70, plays a role in cell cycle regulation in B-CLL and may be used as a prognostic marker in B-CLL monitoring.