Inhibition of Stearoyl-CoA desaturase 1 reverts BRAF and MEK inhibition-induced selection of cancer stem cells in BRAF-mutated melanoma

Abstract

BackgroundCombination therapy with BRAF and MEK inhibitors significantly improves survival in BRAF mutated melanoma patients but is unable to prevent disease recurrence due to the emergence of drug resistance. Cancer stem cells (CSCs) have been involved in these long-term treatment failures. We previously reported in lung cancer that CSCs maintenance is due to altered lipid metabolism and dependent upon Stearoyl-CoA-desaturase (SCD1)-mediated upregulation of YAP and TAZ. On this ground, we investigated the role of SCD1 in melanoma CSCs.MethodsSCD1 gene expression data of melanoma patients were downloaded from TCGA and correlated with disease progression by bioinformatics analysis and confirmed on patient’s tissues by qRT-PCR and IHC analyses. The effects of combination of BRAF/MEKi and the SCD1 inhibitor MF-438 were monitored by spheroid-forming and proliferation assays on a panel of BRAF-mutated melanoma cell lines grown in 3D and 2D conditions, respectively. SCD1, YAP/TAZ and stemness markers were evaluated in melanoma cells and tissues by qRT-PCR, WB and Immunofluorescence.ResultsWe first observed that SCD1 expression increases during melanoma progression. BRAF-mutated melanoma 3D cultures enriched for CSCs overexpressed SCD1 and were more resistant than 2D differentiated cultures to BRAF and MEK inhibitors. We next showed that exposure of BRAF-mutated melanoma cells to MAPK pathway inhibitors enhanced stemness features by upregulating the expression of YAP/TAZ and downstream genes but surprisingly not SCD1. However, SCD1 pharmacological inhibition was able to downregulate YAP/TAZ and to revert at the same time CSC enrichment and resistance to MAPK inhibitors.ConclusionsOur data underscore the role of SCD1 as prognostic marker in melanoma and promote the use of SCD1 inhibitors in combination with MAPK inhibitors for the control of drug resistance.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-0989-7) contains supplementary material, which is available to authorized users.

Reverse transcriptase inhibition potentiates target therapy in BRAF-mutant melanomas: effects on cell proliferation, apoptosis, DNA-damage, ROS induction and mitochondrial membrane depolarization

“…Next day, cells were washed by PBS three times to remove unbound antibodies, then secondary antibody (1:300 dilution) was added in the dark and incubated at room temperature for 1 h. Then cells were stained with Hoechst 33,342 (1:1000 dilution) for 5 min in the dark. Immunofluorescence images of cell lines were performed as previously described [6,31]. For the pH2A.X foci counts at least 8-10 fields were randomly captured from each experimental triplicate [32].…”

Reverse transcriptase inhibition potentiates target therapy in BRAF-mutant melanomas: effects on cell proliferation, apoptosis, DNA-damage, ROS induction and mitochondrial membrane depolarization

“…Next day, cells were washed by PBS three times to remove unbound antibodies, then secondary antibody (1:300 dilution) was added in the dark and incubated at room temperature for 1 h. Then cells were stained with Hoechst 33,342 (1:1000 dilution) for 5 min in the dark. Immuno uorescence images of cell lines were performed as previously described (6,31). For the pH2A.X foci counts at least 8-10 elds were randomly captured from each experimental triplicate (32).…”

“…This therapeutic approach results in rapid and durable objective responses in the majority of patients and in prolonged overall survival. A big issue, however, still remains the emergence of drug resistance (3)(4)(5)(6). From here, the need to identify novel and more e cient combinatorial approaches capable to control the development of drug resistant clones and to avoid disease relapse (7).…”

In Vitro Biophysical and Biological Characterization of Lipid Nanoparticles Co-Encapsulating Oncosuppressors miR-199b-5p and miR-204-5p as Potentiators of Target Therapy in Metastatic Melanoma

“…Our group has been focusing over the last years on the study of non-genetic mechanisms at the basis of drug resistance to MAPKi in BRAF-mutated melanomas [14][15][16]. For example, we have demonstrated that a member of the EGFR family, the ErbB3 receptor, is activated upon exposure to MAPKi by the autocrine production of its ligand neuregulin-1 [17], and that circulating tumor cells (CTCs) derived from melanoma patients undergo up-regulation of ErbB3 phosphorylation in vivo shortly after initiation of therapy [18].…”