Background: BRAF + MEK inhibitors have become the standard of care for melanoma patients (approximately 50%) harboring BRAF-V600 mutations. However, drug resistance often impairs the efficacy of this combinatorial approach. Hence, the need to identify additional therapeutic approaches capable to control the development of drug resistance and to avoid disease relapse. Towards this goal, our group has been largely involved in the last years in the study of non-mutational mechanisms involved in the acquisition of drug resistance. For example, we reported that monoclonal antibodies targeting ErbB3 receptor are able to delay the emergence of resistance to target therapy in vitro and in vivo. More recently, we have also demonstrated that microRNAs are key players of resistance to target therapy in melanoma and that their targeting is able to restore drug sensitivity. Here, we have started to investigate whether reverse transcriptase inhibitors (RTIs) frequently used in the treatment of AIDS can act in combination with target therapy to fight the development of drug resistance. Material and methods: Human melanoma cell lines, namely M14 and A375 harboring BRAF-V600E mutation have been treated with different concentration of either BRAFi and/or MEKi in the presence or not of the non-nucleoside RTI, i.e. SPV122. MTT and colony formation assays have been used to determine cell proliferation. Annexin V assay for apoptosis, cell cycle and mitochondrial membrane depolarization have been tested through FACS analyses. DNA double-strand breaks have been determined through Western Blot and Immunofluorescence analyses. Results: Our present work has reported for the first time the capability of RTIs to mitigate drug resistance to target therapy in BRAF-mutant melanomas in vitro. We show that the novel non-nucleoside RTI, SPV122 synergizes with BRAF and MEK inhibitors to: 1) impair BRAF-mutant melanoma cell growth; 2) induce apoptosis; 3) block cell cycle progression and 4) delay the emergence of resistance in vitro. Mechanistically, we also show that this combination provokes DNA double-strand breaks, mitochondrial membrane depolarization and increased ROS levels. Conclusions: Our in vitro results pave the way for the combinatorial use of RTi + BRAFi + MEKi as a novel therapeutic option for BRAF-mutant melanoma patients and warrant further investigation in in vivo models.
|Titolo:||Reverse transcriptase inhibition potentiates target therapy in BRAF-mutant melanomas: an in vitro study|
|Data di pubblicazione:||2021|
|Appare nelle tipologie:||1.5 Abstract su Rivista|