A Recombinant Adenovirus Expressing Wild-Type Bax Induces Apoptosis in Prostate Cancer Cells Independently of Their Bcl-2 Status and Androgen Sensitivity

Abstract

Using a binary co-transfection strategy of Ad/GT Bax and Ad/PGK-GV16, we have succeeded in inducing overexpression of Bax protein in three prostate cell lines (androgen-insensitive DU145 and PC3, and androgen-sensitive LNCaP). The expression of Bax protein by this system was sufficient to induce all three prostate lines to undergo apoptosis. The fact that DU145 cells which have a p53 mutation and are deficient in Bax, responded to this treatment, suggests that this effect is independent of these pathways. Initiation of the cleavage of Caspase-3 (CPP32/Yama/apopain) and PARP (poly (ADP-ribose) polymerase) by the introduction of Bax were confirmed by western blot analysis. Bcl-2 expression is relevant in the progression of prostate cancer and contributes to an androgen, apoptotic-resistant phenotype in the advanced stages. We examined stable Bcl-2 overexpressing DU145, PC3 and LNCaP cell lines as models of advanced prostate cancer. The adenoviral co-transfection system induced Bax protein expression and apoptosis even in these Bcl-2 transfected cell lines. Taken together, our results suggest that this Bax expression system might represent a useful gene therapy strategy when applied to the treatment of prostate cancer and its efficacy would be independent of the Bcl-2 status and androgen sensitivity of these cancers.

Ribozyme-mediated inhibition of survivin expression increases spontaneous and drug-induced apoptosis and decreases the tumorigenic potential of human prostate cancer cells

“…Specifically, the ability to restore the susceptibility to programmed cell death in DU145 cells that are characterized not only by a high level of expression of antiapoptotic proteins, such as survivin and other IAPs (McEleny et al, 2002), but also by the lack of expression of proapoptotic proteins like Bax (Honda et al, 2001) is particularly relevant. Our data would suggest that in these cells the enhanced apoptotic response is mainly attributable to the almost complete inhibition of survivin, although the concomitant induction of proapoptotic factors like BID (Chao and Korsmeyer, 1998), as indicated by microarray and Western blot analysis, could play an additional role.…”

Hypoxia Response Elements Can Cause the Overexpression of the BAX mRNA Under Hypoxic Condition

“…One of the main proapoptotic proteins is BAX protein of bcl-2 family (2). Many researchers have shown that over expression of BAX gene can overcome anti-apoptotic proteins and cause cancer cells' apoptosis (3,4,31,32). In this study it was shown that BAX over expression can lead to apoptosis in cancer cells.…”

A comprehensive assessment of p53-responsive genes following adenoviral-p53 gene transfer in Bcl-2-expressing prostate cancer cells

“…Stable vector control (PC3-BN) and bcl-2-overexpressing clones (PC3-Bcl-2) were generated from parental PC3 prostate cancer cells (Beham et al, , 1998Herrmann et al, 1997Herrmann et al, , 1998Schumacher et al, 2001;Honda et al, 2002). Western blot analysis confirmed that PC3-Bcl-2 cells express significantly more bcl-2 protein than control PC3-BN cells (data not shown) (Munshi et al, 2001).…”

“…It was of interest to determine if this altered response could also be observed after activation of endogenous wt p53. The LNCaP prostate carcinoma cell line, which is wt for p53, was used to generate vector control (LNCaP-BN) and bcl-2-overexpressing (LNCaP-Bcl-2) clones (Beham et al, , 1998Herrmann et al, 1997Herrmann et al, , 1998Munshi et al, 2001;Schumacher et al, 2001;Honda et al, 2002). Both cell lines were treated with increasing concentrations of the topoisomerase 2 inhibitor etoposide.…”

“…A 1.8 kb fragment of the Bcl-2 cDNA containing the open reading frame was cloned into an expression plasmid (pSFFV-neo). Stable empty vector control cells and bcl-2-overexpressing clones were generated using standard gene transfer techniques and selection in Geneticin (Invitrogen, Carlsbad, CA, USA) and have been previously described in detail (Beham et al, , 1998Herrmann et al, 1997Herrmann et al, , 1998Munshi et al, 2001;Schumacher et al, 2001;Honda et al, 2002). Cell lines were cultured at 371C in a humidified chamber under 5% CO 2 using RPMI 1640 media (Invitrogen) supplemented with 10% FBS, 100 U penicillin and 100 mg/ml streptomycin.…”