Increased therapeutic potential of an experimental anti-mitotic inhibitor SB715992 by genistein in PC-3 human prostate cancer cell line.
BACKGROUND
Kinesin spindle proteins (KSP) are motor proteins that play an essential role in mitotic spindle formation. HsEg5, a KSP, is responsible for the formation of the bipolar spindle, which is critical for proper cell division during mitosis. The function of HsEg5 provides a novel target for the manipulation of the cell cycle and the induction of apoptosis. SB715992, an experimental KSP inhibitor, has been shown to perturb bipolar spindle formation, thus making it an excellent candidate for anti-cancer agent. Our major objective was a) to investigate the cell growth inhibitory effects of SB715992 on PC-3 human prostate cancer cell line, b) to investigate whether the growth inhibitory effects of SB715992 could be enhanced when combined with genistein, a naturally occurring isoflavone and, c) to determine gene expression profile to establish molecular mechanism of action of SB715992.


METHODS
PC-3 cells were treated with varying concentration of SB715992, 30 microM of genistein, and SB715992 plus 30 microM of genistein. After treatments, PC-3 cells were assayed for cell proliferation, induction of apoptosis, and alteration in gene and protein expression using cell inhibition assay, apoptosis assay, microarray analysis, real-time RT-PCR, and Western Blot analysis.


RESULTS
SB715992 inhibited cell proliferation and induced apoptosis in PC-3 cells. SB715992 was found to regulate the expression of genes related to the control of cell proliferation, cell cycle, cell signaling pathways, and apoptosis. In addition, our results showed that combination treatment with SB715992 and genistein caused significantly greater cell growth inhibition and induction of apoptosis compared to the effects of either agent alone.


CONCLUSIONS
Our results clearly show that SB715992 is a potent anti-tumor agent whose therapeutic effects could be enhanced by genistein. Hence, we believe that SB715992 could be a novel agent for the treatment of prostate cancer with greater success when combined with a non-toxic natural agent like genistein.
Davis
David A
DA
Department of Pathology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA. davisad@bu.edu
Sarkar
Sarah H
SH
Hussain
Maha
M
Li
Yiwei
Y
Sarkar
Fazlul H
FH
D050256:Antimitotic Agents / Q000008:administration & dosage*; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D001549:Benzamides / Q000008:administration & dosage*; D015153:Blotting, Western; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D017931:DNA Primers / Q000737:chemistry; D004357:Drug Synergism; D004797:Enzyme-Linked Immunosorbent Assay; D015972:Gene Expression Regulation, Neoplastic; D019833:Genistein / Q000008:administration & dosage*; D006657:Histones / Q000737:chemistry; D006801:Humans; D007529:Isoflavones / Q000737:chemistry; D016547:Kinesins / Q000737:chemistry; D008297:Male; D015233:Models, Statistical; D020411:Oligonucleotide Array Sequence Analysis; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000008:administration & dosage*; D012313:RNA / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D008941:Spindle Apparatus; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology
D050256:Antimitotic Agents; D000970:Antineoplastic Agents; D001549:Benzamides; D050759:Cyclin-Dependent Kinase Inhibitor p21; D017931:DNA Primers; D006657:Histones; D007529:Isoflavones; C470243:KIF11 protein, human; D011799:Quinazolines; D013778:Tetrazolium Salts; D013844:Thiazoles; D012313:RNA; D004247:DNA; C508757:ispinesib; D019833:Genistein; D051057:Proto-Oncogene Proteins c-akt; D016547:Kinesins; C022616:thiazolyl blue