The RhoJ-BAD signaling network: An Achilles' heel for BRAF mutant melanomas.
Ontology highlight
ABSTRACT:
SUBMITTER: Ruiz R
PROVIDER: S-EPMC5549996 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Genes and pathways that allow cells to cope with oncogene-induced stress represent selective cancer therapeutic targets that remain largely undiscovered. In this study, we identify a RhoJ signaling pathway that is a selective therapeutic target for BRAF mutant cells. RhoJ deletion in BRAF mutant melanocytes modulates the expression of the pro-apoptotic protein BAD as well as genes involved in cellular metabolism, impairing nevus formation, cellular transformation, and metastasis. Short-term treatment of nascent melanoma tumors with PAK inhibitors that block RhoJ signaling halts the growth of BRAF mutant melanoma tumors in vivo and induces apoptosis in melanoma cells in vitro via a BAD-dependent mechanism. As up to 50% of BRAF mutant human melanomas express high levels of RhoJ, these studies nominate the RhoJ-BAD signaling network as a therapeutic vulnerability for fledgling BRAF mutant human tumors.
2017-07-26 | GSE101859 | GEO
Project description:Cells must interpret environmental information that often changes over time. In our experiment, we systematically monitored the growth of yeast cells under various frequencies of oscillating osmotic stress. Growth was severely inhibited at a particular resonance frequency, at which cells show hyperactivated transcriptional stress responses. This behavior represents a sensory misperception: The cells incorrectly interpret oscillations as a staircase of ever-increasing osmolarity. The misperception results from the capacity of the osmolarity-sensing mitogen-activated protein kinase (MAPK) network to retrigger with sequential osmotic stresses. Although this feature is critical for coping with natural challenges, such as continually increasing osmolarity, it results in a trade-off of fragility to non-natural oscillatory inputs that match the retriggering time. These findings demonstrate the value of non-natural dynamic perturbations in exposing hidden sensitivities of cellular regulatory networks.
| S-EPMC4721531 | biostudies-literature
Project description:BackgroundBRAF mutations are present in 40% of human skin melanomas. Mutated tumors with an increased percentage of BRAF mutant alleles (BRAF-M%) may have a better response to RAF/MEK inhibitors. We evaluated the BRAF-M% in melanomas, and the genetic causes of its variation.MethodsBRAF-M% was quantified by pyrosequencing, real-time PCR (rtPCR) and/or picoliter-droplet PCR (dPCR). BRAF mutant expression was detected by immunohistochemistry. Chromosomal alterations were analyzed with fluorescence in situ hybridization (FISH), and single nucleotide polymorphism (SNP) arrays.ResultsBRAF-M% quantification obtained with pyrosequencing was highly correlated (R = 0.94) with rtPCR, and with dPCR. BRAF-M% quantified from DNA and RNA were also highly correlated (R = 0.98). Among 368 samples with >80% tumor cells, 38.6% had a BRAF (V600E) mutation. Only 66.2% cases were heterozygous (BRAF-M% 30 to 60%). Increased BRAF-M% (>60%) was observed in 19% of cases. FISH showed a polysomy of chromosome 7 in 13.6%, 35.3% and 54.5% of BRAF wild-type, heterozygous and non-heterozygous BRAF-mutated samples, respectively (P < 0.005). Amplification (5.6%) and loss (3.2%) of BRAF locus were rare. By contrast, chromosome 7 was disomic in 27/27 BRAF-mutated nevi.ConclusionsBRAF-M% is heterogeneous and frequently increased in BRAF-mutant melanomas. Aneuploidy of chromosome 7 is more frequent in BRAF mutant melanomas, specifically in those with high BRAF-M%.
| S-EPMC4491198 | biostudies-literature
Project description:Isolated from the marine bacteria Serinicoccus sp., seriniquinone (SQ1) has been characterized by its selective activity in melanoma cell lines marked by its modulation of human dermcidin and induction of autophagy and apoptosis. While an active lead, the lack of solubility of SQ1 in both organic and aqueous media has complicated its preclinical evaluation. In response, our team turned its effort to explore analogues with the goal of returning synthetically accessible materials with comparable selectivity and activity. The analogue SQ2 showed improved solubility and reached a 30-40-fold greater selectivity for melanoma cells. Here, we report a detailed comparison of the activity of SQ1 and SQ2 in SK-MEL-28 and SK-MEL-147 cell lines, carrying the top melanoma-associated mutations, BRAFV600E and NRASQ61R, respectively. These studies provide a definitive report on the activity, viability, clonogenicity, dermcidin expression, autophagy, and apoptosis induction following exposure to SQ1 or SQ2. Overall, these studies showed that SQ1 and SQ2 demonstrated comparable activity and modulation of dermcidin expression. These studies are further supported through the evaluation of a panel of basal expression of key-genes related to autophagy and apoptosis, providing further insight into the role of these mutations. To explore this rather as a survival or death mechanism, autophagy inhibition sensibilized BRAF mutants to SQ1 and SQ2, whereas the opposite happened to NRAS mutants. These data suggest that the seriniquinones remain active, independently of the melanoma mutation, and suggest the future combination of their application with inhibitors of autophagy to treat BRAF-mutated tumors.
| S-EPMC8658889 | biostudies-literature
Project description:Malignant melanoma is characterized by frequent metastasis, however, specific changes that regulate this process have not been clearly delineated. Although it is well known that Wnt signaling is frequently dysregulated in melanoma, the functional implications of this observation are unclear. By modulating ?-catenin levels in a mouse model of melanoma that is based on melanocyte-specific Pten loss and Braf(V600E) mutation, we demonstrate that ?-catenin is a central mediator of melanoma metastasis to the lymph nodes and lungs. In addition to altering metastasis, ?-catenin levels control tumor differentiation and regulate both MAPK/Erk and PI3K/Akt signaling. Highly metastatic tumors with ?-catenin stabilization are very similar to a subset of human melanomas. Together these findings establish Wnt signaling as a metastasis regulator in melanoma.
| S-EPMC3241928 | biostudies-literature
Project description:Targeted BRAF inhibition (BRAFi) and combined BRAF and MEK inhibition (BRAFi and MEKi) therapies have markedly improved the clinical outcomes of patients with metastatic melanoma. Unfortunately, the efficacy of these treatments is often countered by the acquisition of drug resistance. Here we investigated the molecular mechanisms that underlie acquired resistance to BRAFi and to the combined therapy. Consistent with previous studies, we show that resistance to BRAFi is mediated by ERK pathway reactivation. Resistance to the combined therapy, however, is mediated by mechanisms independent of reactivation of ERK in many resistant cell lines and clinical samples. p21-activated kinases (PAKs) become activated in cells with acquired drug resistance and have a pivotal role in mediating resistance. Our screening, using a reverse-phase protein array, revealed distinct mechanisms by which PAKs mediate resistance to BRAFi and the combined therapy. In BRAFi-resistant cells, PAKs phosphorylate CRAF and MEK to reactivate ERK. In cells that are resistant to the combined therapy, PAKs regulate JNK and ?-catenin phosphorylation and mTOR pathway activation, and inhibit apoptosis, thereby bypassing ERK. Together, our results provide insights into the molecular mechanisms underlying acquired drug resistance to current targeted therapies, and may help to direct novel drug development efforts to overcome acquired drug resistance.
| S-EPMC5891348 | biostudies-literature
Project description:BackgroundThe assessment of calibration performance of risk prediction models based on regression or more flexible machine learning algorithms receives little attention.Main textHerein, we argue that this needs to change immediately because poorly calibrated algorithms can be misleading and potentially harmful for clinical decision-making. We summarize how to avoid poor calibration at algorithm development and how to assess calibration at algorithm validation, emphasizing balance between model complexity and the available sample size. At external validation, calibration curves require sufficiently large samples. Algorithm updating should be considered for appropriate support of clinical practice.ConclusionEfforts are required to avoid poor calibration when developing prediction models, to evaluate calibration when validating models, and to update models when indicated. The ultimate aim is to optimize the utility of predictive analytics for shared decision-making and patient counseling.
| S-EPMC6912996 | biostudies-literature
Project description:Guided by evolutionarily signaled vulnerabilities in the structure of SARS-CoV-2, we identify epitopes in free monomers of the spike protein that steer the generation of induced or administered antibodies geared at promoting destabilization of the virus quaternary structure, thereby hampering infectivity.
| S-EPMC7552172 | biostudies-literature
Project description:Mycobacterial pathogens adapt to environmental stresses such as nutrient deprivation by entering a non-replicative antibiotic-tolerant state of persistence. Using a biochemically-validated data-driven approach, we identified an adaptive metabolic network underlying the mycobacterial response to starvation in M. tuberculosis, M. bovis BCG and M. smegmatis. All three species show a strong Mg+2-dependence for surviving complete nutrient deprivation, accompanied by a broad phenotypic antibiotic resistance. Multivariate analysis of RNA-seq, metabolic phenotyping and biochemical data revealed substantial metabolic remodelling involving a shift to triacylglycerol utilization with adaptation to the consequent ketoacidosis by upregulation of cytochrome P450s. Paradoxically, the ketosis-driven P450 upregulation generated substantial levels of reactive oxygen species (ROS) yet conferred hypersensitivity to killing by hydrogen peroxide-induced inactivation of the P450s that reduced ROS levels. This emergent property of starvation-induced mycobacterial persistence represents a potentially exploitable vulnerability.
2016-08-25 | GSE66883 | GEO
Project description:The development of vemurafenib resistance limits the long-term efficacy of this drug for treatment of metastatic melanomas with the (V600E)BRAF mutation. Inhibition of downstream MAPK signaling with vemurafenib induces apoptotic cell death mediated by caspase-3, suggesting that addition of a procaspase-3 activator could enhance anticancer effects. Here, we show that the combination of PAC-1, a procaspase-activating compound, and vemurafenib is highly synergistic in enhancing caspase-3 activity and apoptotic cell death in melanoma cell lines harboring the (V600E)BRAF mutation. In vivo, the combination displays a favorable safety profile in mice and exerts significant antitumor effects. We further demonstrate that addition of PAC-1 to the clinically useful combination of vemurafenib and a MEK inhibitor, trametinib, starkly enhances the caspase-3 activity and proapoptotic effect of the combination. Moreover, addition of low concentration PAC-1 also delays the regrowth of cells following treatment with vemurafenib. Finally, PAC-1 remains potent against vemurafenib-resistant A375VR cells in cell culture and synergizes with vemurafenib to exert antitumor effects on A375VR cell growth in vivo Collectively, our data suggest that inhibition of MAPK signaling combined with concurrent procaspase-3 activation is an effective strategy to enhance the antitumor activity of vemurafenib and mitigate the development of resistance. Mol Cancer Ther; 15(8); 1859-69. ©2016 AACR.
| S-EPMC4975653 | biostudies-literature