The Plasma Membrane Ca2+ Pump PMCA4b Regulates Melanoma Cell Migration through Remodeling of the Actin Cytoskeleton

Abstract

We demonstrated that the plasma membrane Ca2+ ATPase PMCA4b inhibits migration and metastatic activity of BRAF mutant melanoma cells. Actin dynamics are essential for cells to move, invade and metastasize, therefore, we hypothesized that PMCA4b affected cell migration through remodeling of the actin cytoskeleton. We found that expression of PMCA4b in A375 BRAF mutant melanoma cells induced a profound change in cell shape, cell culture morphology, and displayed a polarized migratory character. Along with these changes the cells became more rounded with increased cell–cell connections, lamellipodia and stress fiber formation. Silencing PMCA4b in MCF-7 breast cancer cells had a similar effect, resulting in a dramatic loss of stress fibers. In addition, the PMCA4b expressing A375 cells maintained front-to-rear Ca2+ concentration gradient with the actin severing protein cofilin localizing to the lamellipodia, and preserved the integrity of the actin cytoskeleton from a destructive Ca2+ overload. We showed that both PMCA4b activity and trafficking were essential for the observed morphology and motility changes. In conclusion, our data suggest that PMCA4b plays a critical role in adopting front-to-rear polarity in a normally spindle-shaped cell type through F-actin rearrangement resulting in a less aggressive melanoma cell phenotype.

The Prognostic Relevance of PMCA4 Expression in Melanoma: Gender Specificity and Implications for Immune Checkpoint Inhibition

“…Our previous preclinical studies indicated a metastasis suppressor function of PMCA4 in melanoma [ 14 , 15 , 16 , 17 ]. Our in silico analysis of a recent large cell line panel with in vivo metastatic potential screen corroborates the putative metastasis suppressor function of PMCA4 [ 45 ].…”

“…Inhibition of this pathway increased the abundance of PMCA4b by increasing its stability [ 16 ]. Finally, PMCA4b was able to inhibit cell migration through the remodeling of the actin cytoskeleton by increasing cell–cell connections as well as lamellipodia and stress fiber formation [ 17 ].…”

Structure, Function and Regulation of the Plasma Membrane Calcium Pump in Health and Disease

“…Naffa et al made the interesting observation that PMCA4b can inhibit the migration of BRAF-mutant melanoma cells and impair their metastatic activity [115]. The authors suggest that by remodeling the actin cytoskeleton, PMCA4b affects the cell migration of those cells.…”

An Approach to Cell Motility as a Key Mechanism in Oncology

“…Melanoma is a classic model to analyze tumor cell migration in clinics and research [ 8 , 9 ] and this collection of Cell Motility and Cancer includes three contributions [ 10 , 11 , 12 ]. An Australian clinical study of 306 metastatic melanomas has found that BRAF + NRAS mutations were associated to the central nervous system and liver metastases, while BRAF mutation was to lymph node metastases and NRAS mutation with lung metastases [ 8 ], so tumor mutation status may advise to direct specifically to these sites the clinical surveillance of these patients.…”

“…The authors conclude that using Tspan8-blocking antibodies would prevent early melanoma from spreading [ 10 ]. Naffa et al [ 11 ] show that PMCA4b, a plasma membrane Ca 2+ key pump in the regulation of cytosolic Ca 2+ concentration, regulates melanoma cell migration via remodeling the actin cytoskeleton. PMCA4b plays a key role in regulating cell polarity through F-actin rearrangement resulting in a less aggressive phenotype.…”