NSC606985, a novel camptothecin analog, induces apoptosis and growth arrest in prostate tumor cells

Abstract

Purpose-Prostate cancer is a major cause of cancer mortality in American males. Once prostate cancer has metastasized, there is currently no curative therapy available. The development of effective agents is therefore a continuing effort to combat this disease. In the present study, the effects and potential mechanisms of NSC606985 (NSC), a water-soluble camptothecin analog, in prostate cancer cells were investigated.Methods-Prostatic tumor cells, DU-145, LNCaP and PC-3, were used for the study. Cell proliferation, cell cycle, cell apoptosis and caspase 3/7 activity were determined in the presence or absence of NSC. The levels of Bax and Bak, and the release of cytochrome c from mitochondria were analyzed by Western blot. Results-Treatment NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript produced a time-and dose-dependent induction of cell apoptosis and cell cycle arrest as evidenced by cell morphological changes, increases in S-phase and sub-G1 cell fractions, an elevation of caspase 3/7 activity, DNA fragmentation and apoptotic cells. NSC increased the levels of apoptotic proteins, Bax and Bak, and induced a release of cytochrome c from mitochondria to cytosol in DU-145 cells. Co-administration of Z-VAD-FMK, a pan-caspase inhibitor, blocked NSC-induced caspase 3/7 activity and cell apoptosis without affecting NSC-induced cell cycle arrest. In contrast, co-administration of a PKCδ inhibitor, rottlerin, had no significant effect on NSC induction of caspase activity, and slightly potentiated NSC-induced cell death. Furthermore, like camptothecin, a mutation of topoi-somerase 1 that prevents the binding of camptothecin to the enzyme completely abolished the NSC effect in DU-145 cells. Conclusion-The data obtained suggest that NSC is able to decrease cell growth, induce cell apoptosis and cause growth arrest in prostatic tumor cells, which may involve an interaction with topoisomerase 1 and an activation of mitochondrial apoptotic pathway.

Camptothecin Induces Apoptosis in Cancer Cells via MicroRNA-125b-Mediated Mitochondrial Pathways

“…CPT is known to exert killing effects by inducing apoptosis in cancer cells (Tan et al, 2009). To reveal whether miR-125b was involved in CPT-induced apoptosis, we investigated the expression patterns of miR-125b during apoptotic stress after CPT treatment.…”

“…One of the major modes of action of these chemotherapeutic drugs may be via the activation of apoptosis (Makin and Dive, 2001). Indeed, several researchers have reported that CPT induces apoptosis in various cancer cells (Sá nchez-Alcá zar et al, 2000;Tan et al, 2009). However, the detailed molecular mechanisms are not fully understood.…”

Dissociation of NSC606985 induces atypical ER-stress and cell death in prostate cancer cells

“…To measure gene expression, RT-PCR and real-time PCR were performed as previously described (15,24). Briefly, total cellular RNA was isolated using TriPure reagents, and the level of specified RNAs were quantified using a NanoDrop2000C.…”

“…Western blotting was carried out following standard methods with minor modifications (15). Briefly, cells were harvested and total cellular proteins were extracted using a RIPA buffer (25 mM Tris-HCl pH 7.6, 150 mM NaCI, 1% NP-40, 1% sodium deoxycholate, 0.1% SDS).…”

“…NSC606985 (NSC), a highly water-soluble camptothecin analog, has recently been demonstrated to produce both caspase-dependent and caspase- independent tumor cell death via differential mechanisms (13,14). In a previous study, we demonstrated the antitumor activity of NSC in prostate cancer cells through the interaction with topoisomerase 1 and an activation of the mitochondrial apoptotic pathway (15). However, the molecular pathway of NSC activation of cell apoptosis in prostate cancer cells remains to be further elucidated.…”