Project description:Metastatic melanoma is an aggressive treatment-refractory malignancy. Recently, c-Kit mutations were discovered in certain mucosal melanomas. A clinical trial was initiated with the c-Kit inhibitor imatinib mesylate. The first treated patient experienced dramatic clinical improvement within days, followed by major responses by PET/CT four weeks later at all sites of metastatic disease. Several established mucosal melanoma cell lines exhibited imatinib sensitivity in a fashion correlating with c-Kit mutational status. Although c-Kit mutations are uncommon in cutaneous melanoma, they may arise in geographically distinct subsets for whom use of c-Kit targeted kinase inhibition should be considered in a rational therapeutic approach. Keywords: Whole genome copy number analysis
Project description:Melanomas on mucosal membranes, acral skin (soles, palms, and nail bed), and skin with chronic sun-induced damage have infrequent mutations in BRAF and NRAS, genes within the mitogenactivated protein (MAP) kinase pathway commonly mutated in melanomas on intermittently sun-exposed skin. This raises the question of whether other aberrations are occurring in the MAP kinase cascade in the melanoma types with infrequent mutations of BRAF and NRAS. Oncogenic mutations in KIT were found in three of seven tumors with amplifications. Examination of all 102 primary melanomas found mutations and/or copy number increases of KIT in 39% ofmucosal, 36% of acral, and 28% of melanomas on chronically sun-damaged skin, but not in any (0%) melanomas on skin without chronic sun damage. Seventy-nine percent of tumors with mutations and 53% of tumors with multiple copies of KIT demonstrated increased KIT protein levels. KIT is an important oncogene in melanoma. Because the majority of the KIT mutations we found in melanoma also occur in imatinib-responsive cancers of other types, imatinib may offer an immediate therapeutic benefit for a significant proportion of the global melanoma burden. Keywords: melanoma, oncogene, comparative genomic hybridization, KIT
Project description:KIT is a key oncogenic driver in triple-wildtype melanoma and represents a rational therapeutic target for KIT inhibitors such as imatinib. However, the tumor immune microenvironment in KIT-altered melanoma and optimal strategies to integrate immunotherapy remain poorly defined. In this study, we found that melanomas harboring KIT mutations or amplifications exhibited reduced CD8⁺ T cell infiltration, indicative of an immune-cold phenotype. Imatinib treatment reversed this Immunosuppressive microenvironment by enhancing CD8⁺ T cell infiltration and cytotoxic activity. Furthermore, imatinib upregulated O-GlcNAc transferase (OGT), which functions as a protein lactyltransferase and increased PD-L1 expression through lysine lactylation, thereby sensitizing tumors to anti–PD-1 therapy. Based on these findings, we conducted an open-label, single-arm phase II clinical trial in patients with advanced or metastatic KIT-altered melanoma. Patients received imatinib monotherapy as induction for six weeks, followed by combination therapy with toripalimab, an anti–PD-1 antibody. The combiniation therapy was well-tolerated and demonstrated encouraging clinical activity, with an objective response rate (ORR) of 59.4% in the overall cohort, 73.9% in patients with exon 11/13 mutations, and 100% in those with exon 11 mutation plus amplification—markedly higher than the ORRs of 23.3% with imatinib monotherapy and 25.7% with anti–PD-1 monotherapy. Median progression-free survival and overall survival were 8.2 months (95% CI, 6.5–9.9) and 15.1 months (95% CI, 13.1–20.8), respectively. These results support the use of imatinib as an immune-sensitizing induction therapy prior to PD-1 blockade in KIT-altered melanoma and highlight the therapeutic relevance of OGT-mediated PD-L1 regulation.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Objective is to identify microRNAs regulated by KIT signaling in mast cells. miRNA profiles of murine bone marrow derived mast cells with and without SCF treatment were compared. In addition, miRNA profiles of the P815 mutant KIT cell line with and without the KIT inhibitor, imatinib, were compared. We identified miRNAs that were differentially regulated by KIT signals.