| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Ji, Zhenyu, et al.
(författare)
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MITF Modulates Therapeutic Resistance through EGFR Signaling.
- 2015
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Ingår i: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 135:7, s. 1863-1872
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Vizoso, Miguel, et al.
(författare)
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Epigenetic activation of a cryptic TBC1D16 transcript enhances melanoma progression by targeting EGFR
- 2015
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 21:7, s. 741-
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Roh, Mi Ryung, et al.
(författare)
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Promoter Methylation of PTEN is a Significant Prognostic Factor in Melanoma Survival.
- 2016
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Ingår i: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 136:5, s. 1002-1011
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Tidskriftsartikel (refereegranskat)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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