Rescue of cell cycle progression in BRAF^V600E inhibitor–resistant human melanoma by a chromatin modifier

Abstract

The BRAF V600E -specific inhibitor vemurafenib blocks mitogen-activated protein kinase pathway and induces cell cycle arrest at G0/G1 phase leading to apoptosis of melanomas. To gain an understanding of the dynamics of cell cycle regulation during vemurafenib therapy, we analyzed several vemurafenib-resistant human melanoma sublines derived from BRAF V600E harboring vemurafenib-sensitive parental lines. Vemurafenib provoked G0/G1 phase arrest in parental but not in vemurafenib-resistant sublines. We hypothesized that refractoriness of vemurafenib-resistant sublines to vemurafenib-mediated cell cycle inhibition can be partially rescued by the chromatin modifier suberoylanilide hydroxamic acid. Suberoylanilide hydroxamic acid promoted G2/M arrest at expense of S phase irrespective of vemurafenib sensitivity. In parental lines, combination of suberoylanilide hydroxamic acid and vemurafenib induced both G0/G1 arrest and apoptosis, whereas in vemurafenib-resistant sublines combination induced G0/G1 as well as G2/M arrest resulting in dramatic cytostasis. Vemurafenib-resistant sublines exhibited extracellular signal-regulated protein kinases 1 and 2 but not AKT and hyperphosphorylation. Gene expression profiling revealed mitogen-activated protein kinase hyperactivation and deregulations of cyclins and cyclin-dependent kinases in vemurafenib-resistant sublines, all of which were reversed by suberoylanilide hydroxamic acid; changes that may explain the cytostatic effects of suberoylanilide hydroxamic acid. These results suggest that unresponsiveness of vemurafenib-resistant sublines to the biological effects of vemurafenib may be amenable by suberoylanilide hydroxamic acid. These in vitro results, while require further investigation, may provide rational biological basis for combination therapy in the management of vemurafenib-resistant melanoma.

Targeting CDC7 sensitizes resistance melanoma cells to BRAFV600E-specific inhibitor by blocking the CDC7/MCM2-7 pathway

“…Based on our findings, BRAF V600E inhibition blocks CDC7-downstream MCM2 and ERK1/2 activities in parental, but not in resistant cells. This was supported by the evidence that Vemurafenib treatment provoked cell cycle arrest associated with cytostatic and cytotoxic effects in parental, but not in resistant cells 38,39 . To further examine whether CDC7 inhibition could sensitize resistant melanoma cells to Vemurafenib, a pharmacologic selective CDC7 inhibitor, TAK-931, was used to manipulate the kinase activity.…”

Identification of pathways modulating vemurafenib resistance in melanoma cells via a genome-wide CRISPR/Cas9 screen

“…The BRAF-V600E mutation is present in approximately 50% of melanoma cases and causes constitutive activation of BRAF and the MAPK (ERK) signaling pathway leading to uncontrolled cell proliferation ( Ascierto et al 2012 ). Vemurafenib binds specifically to the adenosine triphosphate (ATP) binding pocket of activated BRAF-V600E, blocks ERK1/2 activation, and induces cell cycle arrest and apoptosis ( Torres-Collado et al 2017 ). Although there is short-term tumor regression and enhancement of patient survival, resistance to vemurafenib frequently develops ( Ascierto et al 2012 ).…”

miR 204-5p inhibits apoptosis in dacarbazine-treated melanoma cells

“…Another study revealed that treatment of SK-MEL-19 and SK-MEL-27 melanoma cells with prodiginine induced G1/G0 phase arrest and cell apoptosis via downregulating survivin [35]. Furthermore, the BRAF V600E -specific inhibitor, vemurafenib, could inhibit the MAPK pathway, which in turn promoted cell cycle arrest at the G0/G1 phase of the cell cycle, eventually leading to melanoma cell apoptosis [36].…”