Stepwise Combination of Multi-Pathway Blockade in Addition to Radio-Chemotherapy for Glioblastoma

Abstract

Materials/Methods: A PSMA-targeted Glu-Lys urea moiety was conjugated to variably modified DNAPK21, 5’NH2-modified DNAPK27 and 3’NH2-modified DNAPK27 siRNA by amide bond formation from the corresponding active ester. Conjugations used at least a 5:1 ratio of GluLys urea to siRNA. Lipofectamine transfection of the conjugates into LNCaP cells was performed to investigate cellular processing of the siRNA. Treatment without lipofectamine was used to determine if conjugates could independently bind PSMA, internalize and reduce DNAPK mRNA. mRNA levels were determined by RT-PCR. Results: Preliminary results of lipofectamine transfected urea-siRNA conjugates reveal up to 90% knockdown of DNAPK mRNA expression relative to control. Direct treatment of the LNCaP cancer cell line with the urea-5’DNAPK27 conjugate resulted in a 53% DNAPK mRNA knockdown (P Z 0.068), while the urea3’DNAPK27 conjugate demonstrated a 37.6% DNAPK mRNA knockdown (P Z 0.025). The urea-DNAPK21 conjugate yielded 43% DNAPK mRNA knockdown (P<0.01). Conclusions: Cancer cell specific radiosensitization promises to enable tumor control while reducing radiation-induced side effects. We provide results supporting that PSMA-targeted DNAPK siRNA conjugates can be constructed, delivered and successfully targeted to prostate cancer, resulting in reductions in target mRNA in a fashion that may lead to selective prostate cancer radiosensitization. Author Disclosure: M.H. Khattab: None. R.R. Raval: None. Y. Zhang: None. S. Regter: None. M. Hedayati: None. S.R. Banerjee: None. H. Zhou: None. D.V. Ferraris: None. J. Alt: None. C. Rojas: None. B.S. Slusher: None. M.G. Pomper: None. T.L. DeWeese: None.