3 research outputs found
Mclâ1 targeting strategies unlock the proapoptotic potential of TRAIL in melanoma cells
TNFârelated apoptosisâinducing ligand (TRAIL) induces apoptosis selectively in cancer cells. For melanoma, the targeting of TRAIL signaling appears highly attractive, due to pronounced TRAIL receptor expression in tumor tissue. However, mechanisms of TRAIL resistance observed in melanoma cells may limit its clinical use. The Bclâ2 family members are critical regulators of cellâintrinsic apoptotic pathways. Thus, the antiapoptotic Bclâ2 protein myeloid cell leukemia 1 (Mclâ1) is overexpressed in many tumor types and was linked to chemotherapy resistance in melanoma. In this study, we evaluated the involvement of antiapoptotic Bclâ2 proteins (Bclâ2, BclâxL, Bclâw, Mclâ1, BclâA1, and BclâB) in TRAIL resistance. They were targeted by small interfering RNAâmediated silencing in TRAILâsensitive (Aâ375, MelâHO) and in TRAILâresistant melanoma cell lines (Melâ2a, MeWo). This highlighted Mclâ1 as the most efficient target to overcome TRAIL resistance. In this context, we investigated the effects of Mclâ1âtargeting microRNAs as well as the Mclâ1âselective inhibitor S63845. Both miRâ193b and S63845 resulted in significant enhancement of TRAILâinduced apoptosis, associated with decreased cell viability. Apoptosis induction was mediated by caspaseâ3 processing as well as by Bax and Bak activation, indicating the critical involvement of intrinsic apoptosis pathways. These data may indicate a high relevance of Mclâ1 targeting also in melanoma therapy. Furthermore, the data may suggest to consider the use of the tumor suppressor miRâ193b as a strategy for countering TRAIL resistance in melanoma
Cannabinoids reduce melanoma cell viability and do not interfere with commonly used targeted therapy in metastatic melanoma in vivo and in vitro
Background: Cannabinoids are mainly used for recreational purposes, but also made their way into oncology, since these substances can be taken to increase appetite in tumour cachexia. Since there are some hints in the literature that cannabinoids might have some anti-cancerous effects, the aim of this study was to study if and how cannabinoids mediate pro-apoptotic effects in metastatic melanoma in vivo and in vitro and its value besides conventional targeted therapy in vivo.
Methods: Several melanoma cell lines were treated with different concentrations of cannabinoids, and anti-cancerous efficacy was assessed by proliferation and apoptosis assays. Subsequent pathway analysis was performed using apoptosis, proliferation, flow cytometry and confocal microscopy data. The efficacy of cannabinoids in combination with trametinib was studied in NSG mice in vivo.
Results: Cannabinoids reduced cell viability in multiple melanoma cell lines in a dose-dependent way. The effect was mediated by CB1, TRPV1 and PPARα receptors, whereby pharmacological blockade of all three receptors protected from cannabinoid-induced apoptosis. Cannabinoids initiated apoptosis by mitochondrial cytochrome c release with consecutive activation of different caspases. Essentially, cannabinoids significantly decreased tumour growth in vivo and were as potent as the MEK inhibitor trametinib.
Conclusions: We could demonstrate that cannabinoids reduce cell viability in several melanoma cell lines, initiate apoptosis via the intrinsic apoptotic pathway by cytochrome c release and caspase activation and do not interfere with commonly used targeted therapy