P276-00, a cyclin-dependent kinase inhibitor, modulates cell cycle and induces apoptosis in vitro and in vivo in mantle cell lymphoma cell lines.
BACKGROUND
Mantle cell lymphoma (MCL) is a well-defined aggressive lymphoid neoplasm characterized by proliferation of mature B-lymphocytes that have a remarkable tendency to disseminate. This tumor is considered as one of the most aggressive lymphoid neoplasms with poor responses to conventional chemotherapy and relatively short survival. Since cyclin D1 and cell cycle control appears as a natural target, small-molecule inhibitors of cyclin-dependent kinases (Cdks) and cyclins may play important role in the therapy of this disorder. We explored P276-00, a novel selective potent Cdk4-D1, Cdk1-B and Cdk9-T1 inhibitor discovered by us against MCL and elucidated its potential mechanism of action.


METHODS
The cytotoxic effect of P276-00 in three human MCL cell lines was evaluated in vitro. The effect of P276-00 on the regulation of cell cycle, apoptosis and transcription was assessed, which are implied in the pathogenesis of MCL. Flow cytometry, western blot, immunoflourescence and siRNA studies were performed. The in vivo efficacy and effect on survival of P276-00 was evaluated in a Jeko-1 xenograft model developed in SCID mice. PK/PD analysis of tumors were performed using LC-MS and western blot analysis.


RESULTS
P276-00 showed a potent cytotoxic effect against MCL cell lines. Mechanistic studies confirmed down regulation of cell cycle regulatory proteins with apoptosis. P276-00 causes time and dose dependent increase in the sub G1 population as early as from 24 h. Reverse transcription PCR studies provide evidence that P276-00 treatment down regulated transcription of antiapoptotic protein Mcl-1 which is a potential pathogenic protein for MCL. Most importantly, in vivo studies have revealed significant efficacy as a single agent with increased survival period compared to vehicle treated. Further, preliminary combination studies of P276-00 with doxorubicin and bortezomib showed in vitro synergism.


CONCLUSIONS
Our studies thus provide evidence and rational that P276-00 alone or in combination is a potential therapeutic molecule to improve patients' outcome in mantle cell lymphoma.
Target Identification Group, Piramal Healthcare Limited, 1-Nirlon Complex, Goregaon (E), Mumbai, India.
Nitesh P
NP
Shirsath
Sonal M
SM
Manohar
Kalpana S
KS
Joshi
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004357:Drug Synergism; D047309:Flavones / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020128:Inhibitory Concentration 50; D020522:Lymphoma, Mantle-Cell / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011719:Pyrazines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016019:Survival Analysis; D023041:Xenograft Model Antitumor Assays
D000954:Antigens, Surface; D000970:Antineoplastic Agents; D001897:Boronic Acids; C530104:CCND1 protein, human; D047309:Flavones; C115213:LY86 protein, human; D009363:Neoplasm Proteins; C520467:P276-00; D047428:Protein Kinase Inhibitors; D011719:Pyrazines; D034741:RNA, Small Interfering; D019938:Cyclin D1; D000069286:Bortezomib; D004317:Doxorubicin