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Selective cyclin-dependent kinase 2/cyclin A antagonists that differ from ATP site inhibitors block tumor growth
Nerissa Mendoza1, Sharon Fong, Jim Marsters
1Department of Molecular Oncology, Genentech, Inc., South San Francisco, California 94080, USA.
Abstract:
A central function of the tumor suppressor retinoblastoma (Rb) is its ability to repress E2F transcriptional activity. Many cancers harbor inactivated Rb and consequently deregulated E2F. RXL peptides inhibit E2F recruitment and phosphorylation by CDK2/cyclin A. Here we report that RXL peptides selectively kill tumor cells with deregulated Rb/cyclin D pathways. We extend these observations to tumor models and demonstrate inhibition of tumor growth in SV40 large T transformed Balb/c 3T3 grafts and in HER2 transgenic tumors. Moreover, our observations reveal that RXL peptide-treated tumors undergo apoptosis. Our results indicate that RXL motif-based inhibitors will provide selective antiproliferative agents with in vivo efficacy in tumors with deregulated Rb/cyclin D pathways.
Insights
RXL peptides selectively eliminate tumor cells with faulty retinoblastoma (Rb) and cyclin D pathways. These findings show potential for new cancer therapies targeting deregulated cell growth.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- The retinoblastoma (Rb) tumor suppressor protein is crucial for regulating E2F transcriptional activity.
- Inactivation of Rb is common in many cancers, leading to uncontrolled E2F activity.
- RXL peptides are known inhibitors of E2F recruitment and CDK2/cyclin A phosphorylation.
Purpose of the Study:
- To investigate the efficacy of RXL peptides in targeting tumor cells with deregulated Rb/cyclin D pathways.
- To evaluate the anti-tumor effects of RXL peptides in preclinical cancer models.
Main Methods:
- Treatment of tumor cells and models with RXL peptides.
- Assessment of cell viability and tumor growth inhibition.
- Analysis of apoptotic pathways in treated tumors.
Main Results:
- RXL peptides demonstrated selective killing of tumor cells with deregulated Rb/cyclin D pathways.
- Significant inhibition of tumor growth was observed in SV40 large T transformed Balb/c 3T3 grafts and HER2 transgenic tumors.
- RXL peptide treatment induced apoptosis in tumor tissues.
Conclusions:
- RXL motif-based inhibitors show promise as selective antiproliferative agents.
- These inhibitors possess in vivo efficacy against tumors characterized by deregulated Rb/cyclin D pathways.
- RXL peptides represent a potential therapeutic strategy for specific cancer types.