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

Abstract

Impaired expression of connexins, the gap junction subunits that facilitate direct cell-cell communication, have been implicated in prostate cancer growth. To elucidate the crucial role of connexins in prostate cancer progression, we performed a systematic quantitative RT-PCR screening of connexin expression in four representative prostate cancer cell lines across the spectrum of malignancy. Transcripts of several connexin subunits were detected in all four cell lines, and connexin 43 (Cx43) showed marked elevation at both RNA and protein levels in cells with increased metastatic potential. Analysis of gap-junction-mediated intercellular communication revealed homocellular coupling in PC-3 cells, which had the highest Cx43 expression, with minimal coupling in LNCaP cells where Cx43 expression was very low. Treatment with the gap junction inhibitor carbenoxolone or connexin mimetic peptide ACT-1 did not impair cell growth, suggesting that growth is independent of functional gap junctions. PC-3 cells with Cx43 expression reduced by shRNA showed decreased migration in monolayer wound healing assay, as well as decreased transwell invasion capacities when compared to control cells expressing non-targeting shRNA. These results, together with the correlation between Cx43 expression levels and the metastatic capacity of the cell lines, suggest a role of Cx43 in prostate cancer invasion and metastasis.

High mobility group box 1 antagonist limits metastatic seeding in the lungs via reduction of cell-cell adhesion

“…While both A-375 and NIH/3T3 presented a significant inhibition of 30% and 46%, respectively, with 10 μM Carbenoxolone, LLC cells demonstrated no clear effect on proliferation (Supplementary Figure 2). Our results support previous experiments that presented a lack of response in human prostate cell lines which were incubated with considerably higher concentrations of Carbenoxolone over 7 days [39]. Data suggest that rather than affecting proliferation, the main mechanism through which the drug acts in these cells is through targeting other metastatic cellular processes related to cell migration and invasion.…”

Gap junctions and cancer: communicating for 50 years

“…The authors suggested this was due to enhanced intravasation and extravasation, as Cx26 facilitated heterologous GJIC between melanoma cells and endothelial cells ex vivo . Several other studies now suggest that increased connexin expression within the tumour (and even in the tumour stroma 133 ) at late stage disease facilitates metastatic features such as migration and invasion 134-137 (reviewed in 63 ), endothelial adhesion 138,139 , intravasation and extravasation 132,139-143 , and targeting to the metastatic site 144 . In addition, a recent study clearly demonstrates how Cx43 can increase growth of brain metastases at a very late stage, after extravasation and remodelling of existing vascular networks 145 .…”

Tuning Collective Cell Migration by Cell–Cell Junction Regulation

“…Besides cadherins, Ig superfamily members and ephrins/EpH receptor systems were implicated in mediating more labile or transient cell-cell interactions in cancer cells (Cavallaro and Christofori 2004;Haeger et al 2014;Krusche et al 2016). As well, connexins may enable communication through GJs between connected tumor cells and their inhibition reduces collective migration in prostate cancer cells (Zhang et al 2015). Similar to morphogenetic and homeostatic migration, collectives of migrating cancer cells display leader cells that engage with surrounding tissue structures via Rac-driven filopodal protrusions and integrin-mediated substrate adhesion (Hegerfeldt et al 2002;Yamaguchi et al 2015).…”