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Cytoplasmic Cyclin E and Phospho-Cyclin-Dependent Kinase 2 Are Biomarkers of Aggressive Breast Cancer.

ABSTRACT: Cyclin E and its co-activator, phospho-cyclin-dependent kinase 2 (p-CDK2), regulate G1 to S phase transition and their deregulation induces oncogenesis. Immunohistochemical assessments of these proteins in cancer have been reported but were based only on their nuclear expression. However, the oncogenic forms of cyclin E (low molecular weight cyclin E or LMW-E) in complex with CDK2 are preferentially mislocalized to the cytoplasm. Here, we used separate nuclear and cytoplasmic scoring systems for both cyclin E and p-CDK2 expression to demonstrate altered cellular accumulation of these proteins using immunohistochemical analysis. We examined the specificity of different cyclin E antibodies and evaluated their concordance between immunohistochemical and Western blot analyses in a panel of 14 breast cell lines. Nuclear versus cytoplasmic staining of cyclin E readily differentiated full-length from LMW-E, respectively. We also evaluated the expression of cyclin E and p-CDK2 in 1676 breast carcinoma patients by immunohistochemistry. Cytoplasmic cyclin E correlated strongly with cytoplasmic p-CDK2 (P < 0.0001), high tumor grade, negative estrogen/progesterone receptor status, and human epidermal growth factor receptor 2 positivity (all P < 0.0001). In multivariable analysis, cytoplasmic cyclin E plus phosphorylated CDK2 (as one variable) predicted breast cancer recurrence-free and overall survival. These results suggest that cytoplasmic cyclin E and p-CDK2 can be readily detected with immunohistochemistry and used as clinical biomarkers for aggressive breast cancer.

SUBMITTER: Karakas C

PROVIDER: S-EPMC4929404 | biostudies-other | 2016 Jul

REPOSITORIES: biostudies-other

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Cytoplasmic Cyclin E and Phospho-Cyclin-Dependent Kinase 2 Are Biomarkers of Aggressive Breast Cancer.

Karakas Cansu C Biernacka Anna A Bui Tuyen T Sahin Aysegul A AA Yi Min M Akli Said S Schafer Jolie J Alexander Angela A Adjapong Opoku O Hunt Kelly K KK Keyomarsi Khandan K

The American journal of pathology 20160513 7

Cyclin E and its co-activator, phospho-cyclin-dependent kinase 2 (p-CDK2), regulate G1 to S phase transition and their deregulation induces oncogenesis. Immunohistochemical assessments of these proteins in cancer have been reported but were based only on their nuclear expression. However, the oncogenic forms of cyclin E (low molecular weight cyclin E or LMW-E) in complex with CDK2 are preferentially mislocalized to the cytoplasm. Here, we used separate nuclear and cytoplasmic scoring systems for ...[more]

PMID: 27182644

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Project description:OBJECTIVE:To review palbociclib, a novel small-molecule inhibitor of cyclin-dependent kinases 4 and 6, and its current place in therapy for the treatment of hormone receptor (HMR)-positive, human epidermal growth factor receptor 2 (Her2)-negative advanced breast cancer. STUDY SELECTION AND DATA ABSTRACTION:Four phase I trials, 2 phase II trials, and 1 phase III trial were identified from May 2004 to May 2015 using PubMed, American Society of Clinical Oncology (ASCO) abstracts, and European Society of Medical Oncology (ESMO) abstracts. DATA SYNTHESIS:In the first-line setting, the phase II PALbociclib: Ongoing trials in the Management of breast cAncer (PALOMA)-1 trial randomized patients to receive letrozole alone or letrozole plus palbociclib 125 mg daily for 3 weeks, followed by 1 week off, as initial therapy for advanced breast cancer. The investigator-assessed median progression-free survival (PFS) was 20. 2 months for the combination versus 10.2 months for letrozole alone (hazard ratio [HR] = 0.488; 95% CI = 0.319-0.748; 1-sided P = 0.0004). The ensuing Food and Drug Administration approval of palbociclib was given a "breakthrough therapy" designation, where preliminary evidence suggests substantial improvement over existing therapies for a serious or life-threatening disease. A confirmatory phase III trial, PALOMA-2, is under way. In patients who were previously treated with endocrine therapy for advanced breast cancer, the phase III PALOMA-3 trial randomized patients to fulvestrant plus palbociclib versus fulvestrant plus placebo. The investigator-assessed median PFS at the time of a preplanned analysis was 9.2 months with palbociclib-fulvestrant compared with 3.8 months with placebo-fulvestrant (HR = 0.42; 95% CI = 0.32-0.56; P < 0.001). CONCLUSIONS:Palbociclib, the first-in-class CDK4/6 inhibitor, significantly extended PFS in combination with endocrine therapy in the first and subsequent lines of treatment for HMR-positive, Her2-negative advanced breast cancer.

Dataset Information

Cytoplasmic Cyclin E and Phospho-Cyclin-Dependent Kinase 2 Are Biomarkers of Aggressive Breast Cancer.

Publications

Cytoplasmic Cyclin E and Phospho-Cyclin-Dependent Kinase 2 Are Biomarkers of Aggressive Breast Cancer.

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