Potential New Therapeutic Approaches for Cisplatin-Resistant Testicular Germ Cell Tumors.

BACKGROUND: Testicular germ cell tumors (TGCTs), a group of heterogeneous neoplasms, are the most frequent tumors of teenagers and young men, with the incidence rising worldwide. High cure rates can be achieved through cisplatin (CDDP)-based treatment, but approximately 10% of patients present refractory disease and virtually no treatment alternatives. Here, we explored new strategies to treat CDDP-resistant. METHODS: In vitro TGCT CDDP-resistance model was established and differential mRNA expression profiles were evaluated using NanoString technology. Then, TGCT cell lines were treated with four potential drugs (PCNA-I1, ML323, T2AA, and MG-132) to overcome CDDP-resistance. RESULTS: We found several differentially expressed genes related to DNA repair and cell cycle regulation on CDDP-resistant cell line (NTERA-2R) compared to parental cell line (NTERA-2P), and the proteasome inhibitor MG-132 demonstrated cytotoxic activity in all cell lines evaluated, even at a nanomolar range. MG-132 also enhanced cell lines' sensitivity to CDDP, increasing apoptosis in both NTERA-2P and NTERA-2R. CONCLUSIONS: MG-132 emerges as a potential new drug to treat CDDP-resistant TGCT. Targeted therapy based on molecular mechanism insights may contribute to overcome acquired chemotherapy CDDP-resistance.

Loss of 5'-Methylthioadenosine Phosphorylase (MTAP) is Frequent in High-Grade Gliomas; Nevertheless, it is Not Associated with Higher Tumor Aggressiveness.

The 5'-methylthioadenosine phosphorylase (MTAP) gene is located in the chromosomal region 9p21. MTAP deletion is a frequent event in a wide variety of human cancers; however, its biological role in tumorigenesis remains unclear. The purpose of this study was to characterize the MTAP expression profile in a series of gliomas and to associate it with patients' clinicopathological features. Moreover, we sought to evaluate, through glioma gene-edited cell lines, the biological impact of MTAP in gliomas. MTAP expression was evaluated in 507 glioma patients by immunohistochemistry (IHC), and the expression levels were associated with patients' clinicopathological features. Furthermore, an in silico study was undertaken using genomic databases totalizing 350 samples. In glioma cell lines, MTAP was edited, and following MTAP overexpression and knockout (KO), a transcriptome analysis was performed by NanoString Pan-Cancer Pathways panel. Moreover, MTAP's role in glioma cell proliferation, migration, and invasion was evaluated. Homozygous deletion of 9p21 locus was associated with a reduction of MTAP mRNA expression in the TCGA (The Cancer Genome Atlas) - glioblastoma dataset (p < 0.01). In addition, the loss of MTAP expression was markedly high in high-grade gliomas (46.6% of cases) determined by IHC and Western blotting (40% of evaluated cell lines). Reduced MTAP expression was associated with a better prognostic in the adult glioblastoma dataset (p < 0.001). Nine genes associated with five pathways were differentially expressed in MTAP-knockout (KO) cells, with six upregulated and three downregulated in MTAP. Analysis of cell proliferation, migration, and invasion did not show any significant differences between MTAP gene-edited and control cells. Our results integrating data from patients as well as in silico and in vitro models provide evidence towards the lack of strong biological importance of MTAP in gliomas. Despite the frequent loss of MTAP, it seems not to have a clinical impact in survival and does not act as a canonic tumor suppressor gene in gliomas.