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Divergent BRAF Inhibitor Resistance Mechanisms Revealed through Epigenetic Mapping

ABSTRACT: In this report, we generated eight matched pairs of vemurafenib sensitive/resistant melanoma lines and subjected these to concurrent RNA-seq and H3K27Ac ChIP-seq analysis. Globally, we identified two classes of epigenetic profiles that correlate with resistance. Class 1 resistance involves fewer RNA expression alterations accompanied by fewer enhancer mark changes with H3K27Ac. Class 2 resistance shows widespread alterations in transcription and enhancer profiles, which converge on EMT and hypoxia-related pathways. We also observed significant and dynamic changes in super-enhancers that underpin these transcriptomic patterns. We subsequently verified the 2-class structure in pre-BRAFi and post-relapse human melanoma specimens. Our findings reveal a broad and underappreciated spectrum of epigenetic plasticity during acquired BRAFi resistance.

ORGANISM(S): Homo sapiens

PROVIDER: GSE203544 | GEO | 2022/05/25

REPOSITORIES: GEO

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Divergent BRAF Inhibitor Resistance Mechanisms Revealed through Epigenetic Mapping [RNA-seq]

Project description:In this report, we generated eight matched pairs of vemurafenib sensitive/resistant melanoma lines and subjected these to concurrent RNA-seq and H3K27Ac ChIP-seq analysis. Globally, we identified two classes of epigenetic profiles that correlate with resistance. Class 1 resistance involves fewer RNA expression alterations accompanied by fewer enhancer mark changes with H3K27Ac. Class 2 resistance shows widespread alterations in transcription and enhancer profiles, which converge on EMT and hypoxia-related pathways. We also observed significant and dynamic changes in super-enhancers that underpin these transcriptomic patterns. We subsequently verified the 2-class structure in pre-BRAFi and post-relapse human melanoma specimens. Our findings reveal a broad and underappreciated spectrum of epigenetic plasticity during acquired BRAFi resistance.

2022-05-25 | GSE203545 | GEO

Ibrutinib blocks YAP1 activation and reverses BRAFi resistance in melanoma cells

Project description:Most BRAF-mutant melanoma tumors respond initially to BRAFi/MEKi therapy, although few patients have durable long-term responses to these agents. The goal of this study was to utilize an unbiased computational approach to identify inhibitors which reverse an experimentally derived BRAFi resistance gene expression signature. Using this approach, we predicted that ibrutinib, a BTK inhibitor, effectively reverses this signature, and we demonstrate experimentally that ibrutinib re-sensitizes a subset of BRAFi-resistant melanoma cells to vemurafenib. Ibrutinib is used clinically as a BTK inhibitor; however, neither BTK deletion nor treatment with acalabrutinib, an analog of ibrutinib with reduced off-target activity, re-sensitized cells to vemurafenib. These data suggest that ibrutinib acts through a BTK-independent mechanism in vemurafenib re-sensitization. To better understand this mechanism, we analyzed the transcriptional profile of ibrutinib-treated BRAFi-resistant melanoma cells and found that the transcriptional profile of ibrutinib was highly similar to that of multiple SRC kinase inhibitors. Since ibrutinib, but not acalabrutinib, has significant off-target activity against multiple SRC family kinases, it suggests that ibrutinib may be acting through this mechanism. Furthermore, genes either upregulated or downregulated by ibrutinib treatment are enriched with YAP1 target genes and we experimentally demonstrate that ibrutinib, but not acalabrutinib, reduces YAP1 activity in BRAFi-resistant melanoma cells. Taken together, these data suggest that ibrutinib, or other SRC family kinase inhibitors, may be useful for treating some BRAFi/MEKi-refractory melanoma tumors.

2020-02-27 | GSE145990 | GEO

Vemurafenib, BRAF inhibitor, Resistance in BRAFV600E Positive Thyroid Cancer cell lines

Project description:We report the application of single-molecule-based sequencing technology for high-throughput profiling of RNAs in BRAFV600E+ thyroid cancer cell lines 8505C and WRO. We generated genome-wide transcriptome maps of 8505C and WRO cells after vemurafenib, BRAF inhibitor, treatment. In addition, we generated genome-wide transcriptome maps of clonally selected vemurafenib-resistant 8505C and WRO cells with or without vemurafenib treatment. Negative control treatment was 0.1% of dimethy solfoxide (DMSO), the diluent used to resuspend vemurafenib. The treatment regine of vemurafenib was 2 µM concentration for 24 hours. We find that both inducible response to BRAFi and acquired BRAFi resistance in thyroid cancer cells showed significant activation of the JAK/STAT pathway. Our study demonstrates that the JAK/STAT-signaling pathway is activated as thyroid cancer cells develop resistance to BRAFi and that this pathway is a potential target for anticancer activity and to overcome drug resistance that commonly develops to treatment with BRAFi in thyroid cancer and potentially in other malignancies.

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Project description:About half of all melanomas harbor a constitutively active mutant BRAFV600E/K kinase that can be selectively inhibited by targeted BRAF inhibitors (BRAFi). While patients treated with BRAFi initially exhibit measurable clinical improvement, the majority of patients eventually develop drug resistance and relapse. We observe significant elevation of WNT5A in a subset of tumors from patients exhibiting disease progression on BRAFi therapy. WNT5A transcript and protein are also elevated in BRAFi-resistant melanoma cell lines generated by long-term in vitro treatment with BRAFi. RNAi-mediated reduction in levels of endogenous WNT5A in melanoma decreases cell growth, increases apoptosis in response to BRAFi challenge, and decreases the activity of pro-survival AKT signaling. Overexpression of WNT5A conversely promotes melanoma growth and tumorigenesis and activates AKT signaling. Similar to WNT5A knockdown, knockdown of the WNT receptors FZD7 and RYK inhibits growth, sensitizes melanoma cells to BRAFi, and reduces AKT activation. Together, these findings suggest that chronic BRAF inhibition elevates WNT5A expression, which then acts through FZD7 and RYK to promote AKT signaling, leading to increased growth and therapeutic resistance. Increased WNT5A expression in BRAFi-resistant melanomas also correlates with an associated transcriptional signature, which identifies potential therapeutic targets to reduce clinical resistance to BRAFi. Expression of WNT5A-correlated genes was compared in melanoma cell lines generated to be resistant to PLX4032 and the their associated naïve parental line Basal expression of the WNT5A-correlated genes was also measured in experiments comparing each naïve line to a mixed reference pool containing equal amounts of 47 melanoma cell lines.

2014-03-06 | E-GEOD-55583 | biostudies-arrayexpress

BRAF and MEK inhibitor combinations induce potent molecular and immunological effects in NRAS-mutant melanoma cells – insights into mode of action and resistance mechanisms

Project description:About 25% of melanoma harbor activating NRAS mutations, which are associated with aggressive disease therefore requiring a rapid anti-tumor intervention. However, no efficient targeted therapy options are currently available for patients with NRAS-mutant melanoma. MEK inhibitors (MEKi) appear to display a moderate anti-tumor activity and also immunological effects in NRAS-mutant melanoma, providing an ideal backbone for combination treatments. In this study, the MEKi binimetinib, cobimetinib, and trametinib combined with the BRAF inhibitors (BRAFi) encorafenib, vemurafenib, and dabrafenib were investigated for their ability to inhibit proliferation, induce apoptosis and alter the expression of immune modulatory molecules in sensitive NRAS-mutant melanoma cells using 2D and 3D cell culture models and transcriptome analyses. Furthermore, NRAS-mutant melanoma cells resistant to the three BRAFi/MEKi combinations were established to characterize the mechanisms contributing to their resistance. All BRAFi induced a stress response in the sensitive NRAS-mutant melanoma cells thereby significantly enhancing the anti-proliferative and pro-apoptotic activity of the MEKi analyzed. Furthermore, BRAFi/MEKi combinations upregulated immune relevant molecules, such as ICOS-L, components of antigen-presenting machinery and the “don’t eat me signal” molecule CD47 in the melanoma cells. The BRAFi/MEKi-resistant, NRAS-mutant melanoma cells counteracted the molecular and immunological effects of BRAFi/MEKi by upregulating downstream mitogen-activated protein kinase pathway molecules, inhibiting apoptosis and promoting immune escape mechanisms. Together, this study reveals potent molecular and immunological effects of BRAFi/MEKi in sensitive NRAS-mutant melanoma cells that may be exploited in new combinational treatment strategies for patients with NRAS-mutant melanoma.

2023-11-14 | GSE245262 | GEO

Reversing Vemurafenib-resistance in primary melanoma cells by combined Romidepsin and Type I IFN treatment through blocking of tumorigenic signals and induction of immunogenic effects

Project description:BRAFV600 mutations are the most common oncogenic alterations in melanoma cells, supporting proliferation, invasion, metastasis, and immune evasion. In patients, these aberrantly activated cellular pathways are inhibited by BRAFi whose potent antitumor effect and therapeutic potential are dampened by the development of resistance. Here, by using primary melanoma cell lines, generated from lymph node lesions of metastatic patients, we show that the combination of two FDA-approved drugs, the histone deacetylate inhibitor (HDCAi) romidepsin and the immunomodulatory agent IFNα-2b, reduces melanoma proliferation, long-term survival and invasiveness, and overcomes acquired resistance to the BRAFi vemurafenib (VEM). Targeted resequencing revealed that each VEM-resistant melanoma cell line and the parental counterpart are characterized by a distinctive and similar genetic fingerprint, shaping the differential and specific antitumor modulation of MAPK/AKT pathways by combined drug treatment. By using RNA-sequencing and functional in vitro assays, we further report that romidepsin-IFNα-2b treatment restores epigenetically silenced immune signals, modulates MITF and AXL expression, and induces both apoptosis and necroptosis in sensitive and VEM-resistant primary melanoma cells. Moreover, the immunogenic potential of drug-treated VEM-resistant melanoma cells results significantly enhanced, given the increased phagocytosis rate of these cells by dendritic cells, which in turn exhibit also a selective down-modulation of the immune checkpoint TIM-3. Overall, our results provide evidence that combined epigenetic-immune drugs can overcome VEM resistance of primary melanoma cells by oncogenic and immune pathways reprogramming, and pave the way for rapidly exploiting this combination to improve BRAFi-resistant metastatic melanoma treatment, also via reinforcement of immune checkpoint inhibitor therapy.

2023-05-15 | GSE221386 | GEO

Molecular changes induced in melanoma cells by stromal cells and anti-BRAF therapy.

Project description:Tumor-associated stromal cells can enable cancer cells to become insensitive to therapy. They can promote aggressive phenotype in cancer cells, which become less responsive to drugs such as BRAF inhibitors (BRAFi) used to treat melanomas. To clarify potential mechanism behind stromal influence on melanoma, we analyzed gene expression in Melmet 5 melanoma cells grown as mono-cultures or co-cultures with lung fibroblasts with/without BRAFi. We have shown that Melmet 5 growing as co-cultures gained a de-differentiated, invasive transcriptional state, which is known to be linked to BRAFi-resistance. The transcriptional changes induced by BRAFi were much larger in Melmet 5 mono-cultures compared to co-cultures, indicating a much dampened transcriptional response to BRAFi in melanoma under the influence of fibroblasts. We conclude that interaction with the stromal cells stimulate melanoma cell transition to the invasive de-differentiated phenotype, leading to a worse response to BRAF inhibitors. Total RNA was isolated from Melmet 5 cell line growing as mono- or co-cultures with fibroblasts for 72 hours and treated with BRAFi for the last 24 hours.

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Project description:Most genetic events that drive melanoma development and resistance to targeted therapy have been uncovered. In contrast, and despite their increasingly recognized contribution, little is known about the non-genetic mechanisms that drive these processes. Here, we performed in vivo gain-of-function CRISPR screens and identified SMAD3, BIRC3 and SLC9A5 as key drivers of BRAFi-resistance and the tumor growth capability of persister cells. We show that their expression levels increase during acquisition of BRAFi-resistance, and remain high in persister cells and during relapse. Critically, chemical inhibition of SMAD3 or BIRC3 efficiently abrogates melanoma tumor growth and persister cells proliferation. Genetic inhibition of these targets efficiently restored the sensitivity of persister cells to BRAFi. Our work expands our understanding of the biology of persister cells and highlight novel drug vulnerabilities that can be exploited to develop long-lasting anti-melanoma therapies.

2021-02-03 | E-MTAB-8595 | biostudies-arrayexpress

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Project description:Whole-exome sequencing was performed on DNA sample extracted from one melanoma cell line resistant to vemurafenib (BRAF V600E inhibitor). The aim of the experiment was to search for genetic alterations responsible for phenotypic diversity of melanoma cell lines reported at the level of cell morphology, activity of signaling pathways essential for melanoma development and progression, and resistance to targeted therapeutics.

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Gene expression profiling of isogenic malignant melanoma A375-BRAFV600E/NRASQ61 and A375-BRAFV600E/NRASQ61K cell lines

Project description:BRAF-inhibitor (BRAFi)-resistance compromises long term survivorship of malignant melanoma patients, and mutant NRAS is a major mediator of BRAFi-resistance. We have employed NanoString nCounterTM transcriptomic analysis of isogenic human malignant melanoma cells that differ only by NRAS mutational status (BRAFi-sensitive A375-BRAFV600E/NRASQ61 versus BRAFi-resistant A375-BRAFV600E/NRASQ61K), identifying modulation of specific gene expression networks as a function of NRASQ61K-status.

2021-09-23 | GSE184633 | GEO

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