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Deregulation of cyclin E2 expression and associated kinase activity in primary breast tumors
Marc Payton1, Shelia Scully, Grace Chung
1Department of Cancer Biology, Amgen Inc., Thousand Oaks, California, CA 91320, USA.
Abstract:
The increased expression of G(1) cyclins has been associated with the many types of human tumors. In primary solid tumors however, the expression and activity of cyclin E2, the newest member of the G(1) cyclin family, is largely unknown. In this study we have analysed the expression of the E-type cyclins in primary solid tumors from breast, lung, uterus, ovary, colon, and rectal tissues. Relative gene expression was analysed by quantitative real-time reverse transcription polymerase chain reaction (Taqman). The levels of cyclin E1 and cyclin E2 were significantly elevated (23 vs 38%, respectively) in primary breast tumor samples relative to normal breast tissue controls. We also observed an inverse correlation between the expression of cyclin E1/E2 and estrogen receptor in breast tumors. Our results demonstrate that the expression and associated catalytic activity for both cyclin E1 and cyclin E2 is elevated in primary breast tumors when compared to normal breast tissue. The increased level of cyclin E2 in breast tumors suggests that, similar to cyclin E1, it may contribute to the pathogenesis of breast cancer.
Insights
Cyclin E1 and E2 expression is elevated in breast tumors, suggesting a role in cancer development. This study investigated these G(1) cyclins in various solid tumors, focusing on breast cancer.
Area of Science:
- Oncology
- Molecular Biology
- Cell Cycle Regulation
Background:
- G(1) cyclins are linked to human tumors.
- Cyclin E2 expression and activity in primary solid tumors are largely uncharacterized.
- Cyclin E1 and E2 are key regulators of cell cycle progression.
Purpose of the Study:
- To analyze the expression of E-type cyclins (cyclin E1 and E2) in primary solid tumors.
- To investigate the role of cyclin E1 and E2 in breast cancer pathogenesis.
- To compare cyclin E1 and E2 expression in tumor tissues versus normal tissues.
Main Methods:
- Quantitative real-time reverse transcription polymerase chain reaction (Taqman) was used for relative gene expression analysis.
- Expression levels of cyclin E1 and cyclin E2 were measured in breast, lung, uterus, ovary, colon, and rectal tumor samples.
- Breast tumor samples were compared to normal breast tissue controls.
Main Results:
- Cyclin E1 and E2 levels were significantly elevated in primary breast tumor samples compared to normal breast tissue (23% and 38% increase, respectively).
- An inverse correlation was observed between cyclin E1/E2 expression and estrogen receptor status in breast tumors.
- Both cyclin E1 and cyclin E2 expression and catalytic activity were found to be elevated in primary breast tumors.
Conclusions:
- The elevated expression of cyclin E1 and E2 in primary breast tumors suggests their potential contribution to breast cancer development.
- Cyclin E2, like cyclin E1, may play a role in the pathogenesis of breast cancer.
- Further research is warranted to elucidate the precise mechanisms by which these cyclins contribute to tumorigenesis.