BRCA1/BRCA2-containing complex subunit 3 mediates glioma growth and resistance to temozolomide

  • 蔡 潔雯

Student thesis: Master's Thesis


Glioblastoma multiforme (GBM) is the most aggressive form of brain tumors Although the median survival of patients with GBM has been raised up to 18 months by the current glioma treatment using surgery combined with chemotherapy and radiation therapy Yet drug-resistance induced in glioma cells is a critical issue in chemotherapeutic efficiency Previous observations in our laboratory showed that the expression of BRCA1-BRCA2-containing complex subunit 3 (BRCC3) was highly abundant in rat C6 glioma cells BRCC3 a deubiquitinating enzyme which is encoded by the BRCC3 gene in human This molecule has been known as one of the component of DNA repair complex to execute DNA repair in response to DNA damage Previous studies have indicated that BRCC3 acts as a potential target for treatment of breast cancer However the roles of BRCC3 in glioma cells still remain elusive Here we used three human malignant glioma cell lines including U87 U251 and A172 to determine the role of BRCC3 in glioma growth Among the three glioma cell lines A172 cells expressed the highest level of BRCC3 mRNA and exhibited the greatest resistance to temozolomide (TMZ) the alkylating chemotherapeutic agent for glioma treatment When compared to U87 cells U251 cells had a higher BRCC3 mRNA expression and less sensitivity to TMZ Moreover exposure to TMZ resulted in upregulation of BRCC3 mRNA expression in U251 and A172 cells Interestingly the expression of the other genes commonly associated with HR-dependent DNA repair i e BRCA1 BRCA2 RAD51 and FANCD2 were increased in TMZ-treated U251 and A172 cells Apart from that inhibition of BRCC3 using lentivirus-mediated shRNA targeting system was conducted The results showed that depletion of BRCC3 expression significantly suppressed cell growth migration and invasion in U251 and A172 cells In addition BRCC3 gene knockdown improved sensitization of U251 and A172 cells to TMZ Persistent accumulation of intense ?H2AX foci (DNA damage marker) was observed at the later time points post TMZ treatment in U251 and A172 cells with BRCC3 knockdown Further expression of DNA repair genes as indicated above was also downregulated in TMZ-treated U251 and A172 cells when BRCC3 gene expression was inhibited These results indicated that ablation of BRCC3 expression resulted in impairment of DNA repair in TMZ-treated U251 and A172 Collectively our data provides important evidence to show that BRCC3 is critical for glioma cell growth and its upregluation is the responsive factor to induce resistance in human glioma cells to alkylating agents
Date of Award2014 Jul 26
Original languageEnglish
SupervisorShun-Fen Tzeng (Supervisor)

Cite this