ABSTRACT
AIM: The effect of combining sodium butyrate (NaB), a histone deacetylase inhibitor, and 7-hydroxy-staurosporine (UCN-01) on cytotoxicity in human cervical carcinoma cells was evaluated. MATERIALS AND METHODS: HeLa and CaSki cells were treated using NaB alone or in combination with staurosporine (STS) or its analog UCN-01. Cytotoxicity was determined by flow cytometry and morphological assays. Apoptotic pathways were characterized by Western blotting and immunostaining. CaSki cells were also xenografted into nude mice to assess the in vivo effects of NaB/UCN-01 combination. RESULTS: Treatment with NaB and STS or UCN-01 resulted in enhanced apoptosis of cancer cells. Apoptosis involved mitochondrial pathways and overexpression of p53 and p73. In concordance, co-treatment modulated some p53/p73 downstream targets such as p21, BAX, BCL-2 and BCL-X(L), leading to increased caspase-3 and poly(ADP-ribose) polymerase cleavage. In vivo, NaB/UCN-01 combination exerted a substantial tumour growth suppression effect compared with single treatment. CONCLUSION: UCN-01 was shown to be a potentiator of NaB therapy for cervical cancer cells.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Butyrates/pharmacology , Staurosporine/analogs & derivatives , Uterine Cervical Neoplasms/drug therapy , Animals , Apoptosis/drug effects , Butyrates/administration & dosage , Cell Cycle/drug effects , Cell Growth Processes/drug effects , Cell Line, Tumor , Female , HeLa Cells , Human papillomavirus 16/isolation & purification , Human papillomavirus 18/isolation & purification , Humans , Mice , Mice, Nude , Papillomavirus Infections/pathology , Papillomavirus Infections/virology , Staurosporine/administration & dosage , Staurosporine/pharmacology , Uterine Cervical Neoplasms/pathology , Uterine Cervical Neoplasms/virology , Xenograft Model Antitumor AssaysABSTRACT
BACKGROUND INFORMATION: Caspase-dependent and -independent death mechanisms are involved in apoptosis in a variety of human carcinoma cells treated with antineoplastic compounds. Our laboratory has reported that p53 is a key contributor of mitochondrial apoptosis in cervical carcinoma cells after staurosporine exposure. However, higher mitochondrial membrane potential dissipation and greater DNA fragmentation were observed in p53wt (wild-type p53) HeLa cells compared with p53mt (mutated p53) C-33A cells. Here, we have studied events linked to the mitochondrial apoptotic pathway. RESULTS: Staurosporine can induce death of HeLa cells via a cytochrome c/caspase-9/caspase-3 mitochondrial-dependent apoptotic pathway and via a delayed caspase-independent pathway. In contrast with p53wt cells, p53mt C-33A cells exhibit firstly caspase-8 activation leading to caspase-3 activation and Bid cleavage followed by cytochrome c release. Attenuation of PARP-1 [poly(ADP-ribose) polymerase-1] cleavage as well as oligonucleosomal DNA fragmentation in the presence of z-VAD-fmk points toward a major involvement of a caspase-dependent pathway in staurosporine-induced apoptosis in p53wt HeLa cells, which is not the case in p53mt C-33A cells. Meanwhile, the use of 3-aminobenzamide, a PARP-1 inhibitor known to prevent AIF (apoptosis-inducing factor) release, significantly decreases staurosporine-induced death in these p53mt carcinoma cells, suggesting a preferential implication of caspase-independent apoptosis. On the other hand, we show that p53, whose activity is modulated by pifithrin-alpha, isolated as a suppressor of p53-mediated transactivation, or by PRIMA-1 (p53 reactivation and induction of massive apoptosis), that reactivates mutant p53, causes cytochrome c release as well as mitochondrio-nuclear AIF translocation in staurosporine-induced apoptosis of cervical carcinoma cells. CONCLUSIONS: The present paper highlights that staurosporine engages the intrinsic mitochondrial apoptotic pathway via caspase-8 or caspase-9 signalling cascades and via caspase-independent cell death, as well as through p53 activity.
