Inhibition of Pannexin 1 Reduces the Tumorigenic Properties of Human Melanoma Cells

Abstract

Pannexin 1 (PANX1) is a channel-forming glycoprotein expressed in many tissues including the skin. PANX1 channels allow the passage of ions and molecules up to 1 kDa, including ATP and other metabolites. In this study, we show that PANX1 is highly expressed in human melanoma tumors at all stages of disease progression, as well as in patient-derived cells and established melanoma cell lines. Reducing PANX1 protein levels using shRNA or inhibiting channel function with the channel blockers, carbenoxolone (CBX) and probenecid (PBN), significantly decreased cell growth and migration, and increased melanin production in A375-P and A375-MA2 cell lines. Further, treatment of A375-MA2 tumors in chicken embryo xenografts with CBX or PBN significantly reduced melanoma tumor weight and invasiveness. Blocking PANX1 channels with PBN reduced ATP release in A375-P cells, suggesting a potential role for PANX1 in purinergic signaling of melanoma cells. In addition, cell-surface biotinylation assays indicate that there is an intracellular pool of PANX1 in melanoma cells. PANX1 likely modulates signaling through the Wnt/β-catenin pathway, because β-catenin levels were significantly decreased upon PANX1 silencing. Collectively, our findings identify a role for PANX1 in controlling growth and tumorigenic properties of melanoma cells contributing to signaling pathways that modulate melanoma progression.

Pannexin1 Is Associated with Enhanced Epithelial-To-Mesenchymal Transition in Human Patient Breast Cancer Tissues and in Breast Cancer Cell Lines

“…This scenario is supported by data from recent studies on testicular cancer cells, where PANX1 inhibition downregulates EMT genes, upregulates E-cadherin, downregulates MMP-9, and decreases cell invasion [80]. Freeman et al showed that decreasing PANX1 protein levels, in melanoma cells, using shRNA or blocking PANX1 channel using PBN or carbenoxolone decreased cell growth, migration, and invasiveness, probably through the Wnt/β-catenin pathway [83].…”

ATP triggers macropinocytosis that internalizes and is regulated by PANX1

“…Precise regulation of purinergic signalling via PANX1 is critical in many diverse cell types, including maintaining neural stem cell populations [76][77][78], regulating the development of immature neurons [79,80], tumorigenicity [81,82] and metastasis [83] of several cancers [84].…”

“…Precise regulation of purinergic signalling via PANX1 is critical in many diverse cell types, including maintaining neural stem cell populations [76–78], regulating the development of immature neurons [79,80], tumorigenicity [81,82] and metastasis [83] of several cancers [84]. Macropinocytosis is also intimately involved in regulating these processes ([3–11], reviewed in Finicle et al [12] and Bloomfield and Kay [13]).…”

Targeting FER Kinase Inhibits Melanoma Growth and Metastasis

“…Biopsies were dissected by a pathologist immediately after surgery. Primary melanoma cells were isolated and cultured, and total cell lysates were prepared as described [53].…”