Apollon gene silencing induces apoptosis in breast cancer cells through p53 stabilisation and caspase-3 activation.
We analysed the effects of small interfering RNA (siRNA)-mediated silencing of Apollon, a member of the inhibitors of apoptosis protein family, on the proliferative potential and ability of human breast cancer cell lines to undergo apoptosis. In wild-type p53 ZR75.1 cells, Apollon knockdown resulted in a marked, time-dependent decline of cell growth and an increased rate of apoptosis, which was associated with p53 stabilisation and activation of the mitochondrial-dependent apoptotic pathway. Pre-incubation of cells with a p53-specific siRNA resulted in a partial rescue of cell growth inhibition, as well as in a marked reduction of the apoptotic response, indicating p53 as a major player in cell growth impairment consequent on Apollon silencing. Apollon knockdown induced consistently less pronounced anti-proliferative and pro-apoptotic effects in mutant p53 MDA-MB-231 cells than in ZR75.1 cells. Furthermore, the activation of caspase-3 seemed to be essential for the induction of apoptosis after Apollon knockdown, as the Apollon-specific siRNA had no effect on the viability of caspase-3-deficient, wild-type p53 MCF-7 cells or the ZR75.1 cells after RNA interference-mediated caspase-3 silencing. Our results indicate that p53 stabilisation and caspase-3 activation concur to determine the apoptotic response mediated by Apollon knockdown in breast cancer cells, and suggest Apollon to be a potential new therapeutic target for this malignancy.
Lopergolo
A
A
Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
Pennati
M
M
Gandellini
P
P
Orlotti
N I
NI
Poma
P
P
Daidone
M G
MG
Folini
M
M
Zaffaroni
N
N
D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D053148:Caspase 3 / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D005260:Female; D020868:Gene Silencing / Q000502:physiology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D008954:Models, Biological; D055550:Protein Stability / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology* / Q000627:therapeutic use; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
C401541:BIRC6 protein, human; D051034:Inhibitor of Apoptosis Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D053148:Caspase 3