RESUMO
Overcoming temozolomide (TMZ)-resistance is a major challenge in glioblastoma therapy. Therefore, identifying the key molecular player in chemo-resistance becomes urgent. We previously reported the downregulation of PDCD10 in primary glioblastoma patients and its tumor suppressor-like function in glioblastoma cells. Here, we demonstrate that the loss of PDCD10 causes a significant TMZ-resistance during treatment and promotes a rapid regrowth of tumor cells after treatment. PDCD10 knockdown upregulated MGMT, a key enzyme mediating chemo-resistance in glioblastoma, accompanied by increased expression of DNA mismatch repair genes, and enabled tumor cells to evade TMZ-induced cell-cycle arrest. These findings were confirmed in independent models of PDCD10 overexpressing cells. Furthermore, PDCD10 downregulation led to the dedifferentiation of glioblastoma cells, as evidenced by increased clonogenic growth, the upregulation of glioblastoma stem cell (GSC) markers, and enhanced neurosphere formation capacity. GSCs derived from PDCD10 knockdown cells displayed stronger TMZ-resistance and regrowth potency, compared to their parental counterparts, indicating that PDCD10-induced stemness may independently contribute to tumor malignancy. These data provide evidence for a dual role of PDCD10 in tumor suppression by controlling both chemo-resistance and dedifferentiation, and highlight PDCD10 as a potential prognostic marker and target for combination therapy with TMZ in glioblastoma.
Assuntos
Proteínas Reguladoras de Apoptose , Resistencia a Medicamentos Antineoplásicos , Glioblastoma , Temozolomida , Humanos , Glioblastoma/patologia , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/tratamento farmacológico , Temozolomida/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Linhagem Celular Tumoral , Proteínas Reguladoras de Apoptose/metabolismo , Proteínas Reguladoras de Apoptose/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/tratamento farmacológico , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas/genética , Proliferação de Células/efeitos dos fármacos , Metilases de Modificação do DNA/metabolismo , Metilases de Modificação do DNA/genética , Proteínas Supressoras de Tumor/metabolismo , Proteínas Supressoras de Tumor/genética , Enzimas Reparadoras do DNA/metabolismo , Enzimas Reparadoras do DNA/genéticaRESUMO
Temozolomide (TMZ) is the first line of standard therapy in glioblastoma (GBM). However, relapse occurs due to TMZ resistance. We attempted to establish an acquired TMZ resistance model that recapitulates the TMZ resistance phenotype and the relevant gene signature. Two GBM cell lines received two cycles of TMZ (150 µM) treatment for 72 h each. Regrown cells (RG2) were defined as TMZ resistant cells. MTT assay revealed significantly less susceptibility and sustained growth of RG2 compared with parental cells after TMZ challenge. TMZ-induced DNA damage significantly decreased in 53BP1-foci reporter transduced-RG2 cells compared with parental cells, associated with downregulation of MSH2 and MSH6. Flow cytometry revealed reduced G2/M arrest, increased EdU incorporation and suppressed apoptosis in RG2 cells after TMZ treatment. Colony formation and neurosphere assay demonstrated enhanced clonogenicity and neurosphere formation capacity in RG2 cells, accompanied by upregulation of stem markers. Collectively, we established an acute TMZ resistance model that recapitulated key features of TMZ resistance involving impaired mismatch repair, redistribution of cell cycle phases, increased DNA replication, reduced apoptosis and enhanced self-renewal. Therefore, this model may serve as a promising research tool for studying mechanisms of TMZ resistance and for defining therapeutic approaches to GBM in the future.