Background: Temozolomide-resistant (TMZ-R) glioblastoma is very difficult to treat, and a novel approach to overcome resistance is needed.
Materials and methods: The efficacy of a combination treatment of STAT3 inhibitor, STX-0119, with rapamycin was investigated against our established TMZ-resistant U87 cell line.
Results: The growth-inhibitory effect of the combination treatment was significant against the TMZ-R U87 cell line (IC50: 78 μM for STX-0119, 30.5 μM for rapamycin and 11.3 μM for combination of the two). Western blotting analysis demonstrated that the inhibitory effect of STX-0119 on S6 and 4E-BP1 activation through regulation of YKL-40 expression occurred in addition to the inhibitory effect of rapamycin against the mTOR pathway.
Conclusion: These results suggest that the STAT3 pathway is associated with the mTOR downstream pathway mediated by YKL-40 protein, and the combination therapy of the STAT3 inhibitor and rapamycin could be worth developing as a novel therapeutic approach against TMZ-resistant relapsed gliomas.
Keywords: STAT3 inhibitor; glioblastoma; mTOR inhibitor; temozolomide resistance.
Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.