Project description:Despite increasing amounts of experimental evidence depicting the involvement of non-coding RNAs in cancer, the study of BRAFV600E-regulated genes has thus far focused mainly on protein-coding ones. Here, we identify and study the microRNAs that BRAFV600E regulates through the ERK pathway.By performing small RNA sequencing on A375 melanoma cells and a vemurafenib-resistant clone that was taken as negative control, we discover miR-204 and miR-211 as the miRNAs most induced by vemurafenib. We also demonstrate that, although belonging to the same family, these two miRNAs have distinctive features. miR-204 is under the control of STAT3 and its expression is induced in amelanotic melanoma cells, where it acts as an effector of vemurafenib's anti-motility activity by targeting AP1S2. Conversely, miR-211, a known transcriptional target of MITF, is induced in melanotic melanoma cells, where it targets EDEM1 and consequently impairs the degradation of TYROSINASE (TYR) through the ER-associated degradation (ERAD) pathway. In doing so, miR-211 serves as an effector of vemurafenib's pro-pigmentation activity. We also show that such an increase in pigmentation in turn represents an adaptive response that needs to be overcome using appropriate inhibitors in order to increase the efficacy of vemurafenib.In summary, we unveil the distinct and context-dependent activities exerted by miR-204 family members in melanoma cells. Our work challenges the widely accepted "same miRNA family = same function" rule and provides a rationale for a novel treatment strategy for melanotic melanomas that is based on the combination of ERK pathway inhibitors with pigmentation inhibitors.
Project description:Despite increasing amounts of experimental evidence depicting the involvement of non-coding RNAs in cancer, the study of BRAFV600E-regulated genes has thus far focused mainly on protein-coding ones. Here, we identify and study the microRNAs that BRAFV600E regulates through the ERK pathway. By performing small RNA sequencing on A375 melanoma cells and a vemurafenib- resistant clone that was taken as negative control, we discover miR-204 and miR-211 as the miRNAs most induced by vemurafenib. We also demonstrate that, although belonging to the same family, these two miRNAs have distinctive features. miR-204 is under the control of STAT3 and its expression is induced in amelanotic melanoma cells, where it acts as an effector of vemurafenib’s anti-motility activity by targeting AP1S2. Conversely, miR-211, a known transcriptional target of MITF, is induced in melanotic melanoma cells, where it targets EDEM1 and consequently impairs the degradation of TYROSINASE (TYR) through the ER-associated degradation (ERAD) pathway. In doing so, miR-211 serves as an effector of vemurafenib’s pro-pigmentation activity. We also show that such an increase in pigmentation in turn represents an adaptive response that needs to be overcome using appropriate inhibitors in order to increase the ef cacy of vemurafenib. In summary, we unveil the distinct and context-dependent activities exerted by miR-204 family members in melanoma cells. Our work challenges the widely accepted “same miRNA family = same function” rule and provides a rationale for a novel treatment strategy for melanotic melanomas that is based on the combination of ERK pathway inhibitors with pigmentation inhibitors.
Project description:Despite increasing amounts of experimental evidence depicting the involvement of non-coding RNAs in cancer, the study of BRAFV600E-regulated genes has thus far focused mainly on protein-coding ones. Here, we identify and study the microRNAs that BRAFV600E regulates through the ERK pathway. By performing small RNA sequencing on A375 melanoma cells and a vemurafenib- resistant clone that was taken as negative control, we discover miR-204 and miR-211 as the miRNAs most induced by vemurafenib. We also demonstrate that, although belonging to the same family, these two miRNAs have distinctive features. miR-204 is under the control of STAT3 and its expression is induced in amelanotic melanoma cells, where it acts as an effector of vemurafenib’s anti-motility activity by targeting AP1S2. Conversely, miR-211, a known transcriptional target of MITF, is induced in melanotic melanoma cells, where it targets EDEM1 and consequently impairs the degradation of TYROSINASE (TYR) through the ER-associated degradation (ERAD) pathway. In doing so, miR-211 serves as an effector of vemurafenib’s pro-pigmentation activity. We also show that such an increase in pigmentation in turn represents an adaptive response that needs to be overcome using appropriate inhibitors in order to increase the ef cacy of vemurafenib. In summary, we unveil the distinct and context-dependent activities exerted by miR-204 family members in melanoma cells. Our work challenges the widely accepted “same miRNA family = same function” rule and provides a rationale for a novel treatment strategy for melanotic melanomas that is based on the combination of ERK pathway inhibitors with pigmentation inhibitors.
Project description:In this short report, we pinpoint some technical and conceptual flaws that we found in the article entitled "miR-204-5p and miR-211-5p contribute to BRAF inhibitor resistance in melanoma" (Díaz-Martínez et al., Cancer Research 2018). We also discuss how, in our opinion, these flaws led Díaz-Martínez and colleagues to incorrect conclusions about the biological role that miR-204 and miR-211 play in melanoma and about the terms of their involvement in the phenomenon of resistance to BRAF inhibitors.
Project description:Melanoma is a form of skin cancer that can rapidly invade distant organs. A distinctive feature of melanomas is their pigmentation status, as melanin is present in most skin melanomas, whilst many metastatic tumors could become amelanotic. Besides the obvious malfunction of the key genes of the melanin pathway, the amelanotic tumors could bear a characteristic molecular signature accounting for their aggressivity. Using mass spectrometry-based proteomics we report here a distinctive panel of biomarkers for amelanotic aggressive melanoma that differ from the less invasive pigmented cells. The developed method allows the label-free quantification of proteins identified by LC-MS/MS analysis. We found a set of proteins comprising AHNAK, MYOF, ANXA1, CAPN2, ASPH, EPHA2, THBS1, TGM2, ACTN4 along with proteins involved in cell adhesion/migration (integrins, PLEC, FSCN1, FN1) that are highly expressed in amelanotic melanoma. Accompanying the down regulation of pigmentation specific proteins such as tyrosinase and TYRP1, these biomarkers are highly specific for a type of highly invasive melanoma. Interestingly, the LC-MS/MS proteomics analysis in hypoxia revealed that the abundance of this specific set of proteins found in normoxia was rather unaltered in these conditions. These biomarkers could therefore predict a metastatic behaviour for the amelanotic cells in the early stages of the tumor development and thus serve in melanoma prognostic. Applying this algorithm to related databases including melanoma samples published by independent laboratories/public databases we confirm the specificity of the newly found signatures. Overall, we begin to unravel the molecular alterations in the amelanotic melanoma and how basic proteomics offers insights into how to assess the clinical, pathological and misdiagnosis differences between the main subtypes of melanoma.
Project description:Purpose: Identification of miRNAs that enable resistance to BRAF inhibitors in melanoma suggests a mechanism-based strategy to limit resistance and improve clinical outcomes. Methods: We generated A375 melanoma cells resistant to Vemurafenib (VMF) with the goal of investigating changes in miRNA expression patterns that might contribute to resistance. Results: Increased expression of miR-204-5p and miR-211-5p occurring in VMF-resistant cells was determined to impact VMF response.
Project description:We analyzed an inducible melanoma model in TiRP Ink4a/ArfF/F B10.D2 mice based on the conditional deletion in melanocytes of two tumor suppressor genes INK4a/Arf coupled to the expression of the oncogene H-rasG12V and a known tumor antigen (Hujibers et al. Cancer Res. 66:3278,2006; Soudja et al. Cancer Res. 70:3515-3525,2010). About 40% of these mice develop melanomas. Some tumors are heavily pigmented melanotic melanoma and grow slowly (hereafter referred to as “Mela”), but most of the induced tumors are nonpigmented amelanotic melanomas which are more aggressive (hereafter referred to as “Amela”). Gene expression profiles of the two types of tumors and of Amela-derived cell lines established in vitro were analyzed to identify the transcriptional signatures of these two types of tumors (including stromal components and infiltrating cells), as well as that intrinsic to Amela-tumor cells. 4 Amela and 4 Mela ex-vivo tumors were compared in a dye-swap experiment (8 chips). 4 Amela and 4 Mela ex-vivo tumors were compared to healthy skin (CTRL) (8 chips). 4 Amela ex-vivo tumors and Amela cell lines were compared in a dye-swap experiment (8 chips).
Project description:We analyzed an inducible melanoma model in TiRP Ink4a/ArfF/F B10.D2 mice based on the conditional deletion in melanocytes of two tumor suppressor genes INK4a/Arf coupled to the expression of the oncogene H-rasG12V and a known tumor antigen (Hujibers et al. Cancer Res. 66:3278,2006; Soudja et al. Cancer Res. 70:3515-3525,2010). About 40% of these mice develop melanomas. Some tumors are heavily pigmented melanotic melanoma and grow slowly (hereafter referred to as “Mela”), but most of the induced tumors are nonpigmented amelanotic melanomas which are more aggressive (hereafter referred to as “Amela”). Gene expression profiles of the two types of tumors and of Amela-derived cell lines established in vitro were analyzed to identify the transcriptional signatures of these two types of tumors (including stromal components and infiltrating cells), as well as that intrinsic to Amela-tumor cells.