| 1. |
- Ji, Zhenyu, et al.
(author)
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MITF Modulates Therapeutic Resistance through EGFR Signaling.
- 2015
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In: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 135:7, s. 1863-1872
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Journal article (peer-reviewed)abstract
- Response to targeted therapies varies significantly despite shared oncogenic mutations. Nowhere is this more apparent than in BRAF(V600E)-mutated melanomas where initial drug response can be striking and yet relapse is commonplace. Resistance to BRAF inhibitors have been attributed to the activation of various receptor tyrosine kinases (RTKs) though the underlying mechanisms have been largely uncharacterized. Here, we found that EGFR induced vemurafenib resistance is ligand dependent. We then employed whole-genome expression analysis and discovererd that vemurafenib resistance correlated with the loss of MITF, along with its melanocyte lineage program, and with the activation of EGFR signaling. An inverse relationship between MITF, vemurafenib resistance and EGFR was then observed in patient samples of recurrent melanoma and was conserved across melanoma cell lines and patients' tumor specimens. Functional studies revealed that MITF depletion activated EGFR signaling and consequently recapitulated the resistance phenotype. In contrast, forced expression of MITF in melanoma and colon cancer cells inhibited EGFR and conferred sensitivity to BRAF/MEK inhibitors. These findings indicate that an "autocrine drug resistance loop" is suppressed by melanocyte lineage signal(s), such as MITF. This resistance loop modulates drug response and could explain the unique sensitivity of melanomas to BRAF inhibition.Journal of Investigative Dermatology accepted article preview online, 19 March 2015. doi:10.1038/jid.2015.105.
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| 2. |
- Ji, Zhenyu, et al.
(author)
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Vemurafenib Synergizes with Nutlin-3 to Deplete Survivin and Suppresses Melanoma Viability and Tumor Growth
- 2013
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In: Clinical Cancer Research. - 1078-0432. ; 19:16, s. 4383-4391
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Journal article (peer-reviewed)abstract
- Purpose: For patients with advanced melanoma, primary and secondary resistance to selective BRAF inhibition remains one of the most critically compelling challenges. One rationale argues that novel biologically informed strategies are needed to maximally cripple melanoma cells up front before compensatory mechanisms emerge. As p53 is uncommonly mutated in melanoma, restoration of its function represents an attractive adjunct to selective BRAF inhibition. Experimental Design: Thirty-seven BRAF(V600E)-mutated melanoma lines were subjected to synergy studies in vitro using a combination of vemurafenib and nutlin-3 (Nt-3). In addition, cellular responses and in vivo efficacy were also determined. We also analyzed changes in the levels of canonical apoptotic/survival factors in response to vemurafenib. Results: Dual targeting of BRAF(V600E) and Hdm2 with vemurafenib and Nt-3, respectively, synergistically induced apoptosis and suppressed melanoma viability in vitro and tumor growth in vivo. Suppression of p53 in melanoma cells abrogated Nt-3's effects fully and vemurafenib's effects partially. A survey of canonical survival factors revealed that both vemurafenib and Nt-3 independently attenuated levels of the antiapoptotic protein, survivin. Genetic depletion of survivin reproduces the cytotoxic effects of the combination strategy. Conclusion: These results show preclinical feasibility for overcoming primary vemurafenib resistance by restoring p53 function. Moreover, it identifies survivin as one downstream mediator of the observed synergism and a potential secondary target. (C)2013 AACR.
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| 3. |
- Roh, Mi Ryung, et al.
(author)
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Promoter Methylation of PTEN is a Significant Prognostic Factor in Melanoma Survival.
- 2016
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In: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 136:5, s. 1002-1011
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Journal article (peer-reviewed)abstract
- Structural compromise of the tumor suppressor gene, PTEN occurs in 10% of melanoma specimens and loss of PTEN expression through DNA methylation of the PTEN promoter region has also been reported in a number of other malignancies. However, the role of PTEN promoter methylation in melanoma is not well understood. We thus sought to elucidate the prevalence of PTEN promoter methylation in melanoma specimens, its relationship to clinical features and its impact on the outcome of melanoma patients. PTEN promoter methylation data was acquired from an archived primary Korean melanoma cohort (KMC) of 158 patients and, for validation, 234 patients from The Cancer Genome Atlas melanoma cohort (TCGA-MEL). Hierarchical clustering was performed to identify PTEN "high methylated" and "low methylated" samples. Subsequently, differences in clinical features and outcomes based on PTEN promoter methylation status were then analyzed using SPSS and R. In the KMC, all tumors were acquired from primary tumors and 65.7% (n=105) were acral or mucosal by site, whereas in TCGA-MEL, 90.5% of the tumors were from regional lymph node and distant metastatic lesions. Overall, 17.7% and 45.7% of the specimens harbored BRAF mutations in the KMC and TCGA-MEL, respectively. NRAS was mutated in 12.2% and 26.9% of the tumors in the KMC and TCGA-MEL, respectively. In KMC, 31 cases (19.6%) were included in the high methylated group versus 142 cases (60.7%) in the TCGA-MEL cohort (P<0.001). Multivariate Cox-regression analysis revealed promoter methylation of PTEN to be an independent negative prognostic factor for survival in both the KMC (HR 3.76, 95% CI=1.24 to 11.12, P=0.017) and TCGA-MEL (HR 1.88, 95% CI=1.13 to 3.12, P=0.015). Our results indicate that PTEN promoter methylation is an independent predictor for impaired survival in melanoma patients.
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| 4. |
- Silverstein, Arthur, et al.
(author)
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Evolution of biomarker research in autoimmunity conditions for health professionals and clinical practice
- 2022
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In: Precision medicine. - : Elsevier. - 9780323997843 ; , s. 219-276
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Book chapter (peer-reviewed)abstract
- Medical abzymology has made a great contribution to the development of general autoimmunity theory: it has put the autoantibodies (Ab) as the key brick of the theory to the level of physiological functionality by providing such Ab with the ability to catalyze and mediate direct and independent cytotoxic effect on cellular and molecular targets. Natural catalytic autoantibodies (abzymes) while being a pool of canonical Abs and possessing catalytic activity belong to the new group of physiologically active substances whose features and properties are evolutionary consolidated in one functionally active biomolecule. Therefore, further studies on Ab-mediated autoAg degradation and other targeted Ab-mediated proteolysis may provide biomarkers of newer generations and thus a supplementary tool for assessing the disease progression and predicting disability of the patients and persons at risks. This chapter is a summary of current knowledge and prognostic perspectives toward catalytic Abs in autoimmunity and thus some autoimmune clinical cases, their role in pathogenesis, and the exploitation of both whole molecules and their constituent parts in developing highly effective targeted drugs of the future to come, and thus the therapeutic protocols being individualized.
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| 5. |
- Vizoso, Miguel, et al.
(author)
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Epigenetic activation of a cryptic TBC1D16 transcript enhances melanoma progression by targeting EGFR
- 2015
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In: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 21:7, s. 741-
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Journal article (peer-reviewed)abstract
- Metastasis is responsible for most cancer-related deaths, and, among common tumor types, melanoma is one with great potential to metastasize. Here we study the contribution of epigenetic changes to the dissemination process by analyzing the changes that occur at the DNA methylation level between primary cancer cells and metastases. We found a hypomethylation event that reactivates a cryptic transcript of the Rab GTPase activating protein TBC1D16 (TBC1D16-47 kDa; referred to hereafter as TBC1D16-47KD) to be a characteristic feature of the metastatic cascade. This short isoform of TBC1D16 exacerbates melanoma growth and metastasis both in vitro and in vivo. By combining immunoprecipitation and mass spectrometry, we identified RAB5C as a new TBC1D16 target and showed that it regulates EGFR in melanoma cells. We also found that epigenetic reactivation of TBC1D16-47KD is associated with poor clinical outcome in melanoma, while conferring greater sensitivity to BRAF and MEK inhibitors.
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| 6. |
- Niemi, MEK, et al.
(author)
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- 2021
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swepub:Mat__t
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