To the Editors: Schildkraut et al. (1) report that the relationship between calculated lifetime number of ovulatory cycles (LOC) and risk of epithelial ovarian cancer is significantly stronger among cancer cases overexpressing cyclin E than those not overexpressing it. They conclude that this difference provides evidence for the involvement of repeated ovulation in the etiology of ovarian cance...

Cdc25A, a phosphatase essential for G1-S transition, associates with, dephosphorylates, and activates the cell cycle kinase cyclin E-cdk2. p21CIP1 and p27 are cyclin-dependent kinase (cdk) inhibitors induced by growth-suppressive signals such as p53 and transforming growth factor beta (TGF-beta). We have identified a cyclin binding motif near the N terminus of Cdc25A that is similar to the cycl...

OBJECTIVE To evaluate endometrial expression of cyclin E and p27 in fertile and infertile women. DESIGN Retrospective clinical study. SETTING University medical center and private practice. PATIENT(S) Thirty-three fertile volunteers, 83 women seeking infertility treatment, and 23 women undergoing mock cycles. INTERVENTION(S) Endometrial biopsy. MAIN OUTCOME MEASURE(S) Cyclin E and p27...

The transcription factor E2F plays crucial roles in induction of S phase in mammalian cells by regulating the expression of genes that encode molecules involved in cell cycle progression. E2F exerts a repressive effect on E2F-responsive genes in G0/G1 phase by associating with the retinoblastoma tumor suppressor gene product pRb and the related protein p130. This repression is relieved by phosp...

PURPOSE Low-molecular-weight cyclin E (LMW-E) in breast cancer cells induces genomic instability and resistance to inhibition by p21, p27, and fulvestrant therapy. Here, we sought to determine if LMW-E renders breast cancer cells unresponsive to aromatase inhibitors (AI), elucidate the mechanism of such resistance, and ascertain if inhibitors of LMW-E-associated kinase activity could overcome t...

background: esophageal squamous cell carcinoma (escc) is one of the lethal cancers with a high incidence rate in asia. many genes including cyclin d1 and p16 play important role in its carcinogenesis. we aimed to analyze the expressions of cyclin d1 and p16 with the various clinicopathological characteristics of escc.   method: we examined 30 biopsy samples of escc for cyclin d1 and p16 protein...

Normal, nontumorous cells express cyclin proteins in an orderly, scheduled fashion, at a given phase of the cell cycle. Thus, cyclin B1 is synthesized during G2 and abruptly degraded during mitosis. The onset of cyclin E synthesis takes place in mid-G1, its maximal expression is at the time of cell entrance to S, and its degradation occurs during cell progression through S phase. In the present...

Cyclin E and the cyclin-dependent kinase inhibitor p27 are two important regulators of the G1-S transition modulating the activity of cyclin-dependent kinases. Aberrations in the cell cycle control are often observed in tumors and might even be mandatory in tumor development. To investigate the importance of cell-cycle defects in malignant lymphomas we have characterized the expression of cycli...

The capacity of the cyclin D-dependent kinase to promote G(1) progression through modulation of RB.E2F is well documented. We now demonstrate that the cyclin D1/CDK4 kinase binds to components of the MCM complex. MCM7 and MCM3 were identified as cyclin D1-binding proteins. Catalytically active cyclin D1/CDK4 complexes were incorporated into chromatin-bound protein complexes with the same kineti...

Cyclins A and E and their partner cyclin-dependent kinases (Cdks) are key regulators of DNA synthesis and of mitosis. Immunofluorescence studies have shown that both cyclins are nuclear and that a proportion of cyclin A is localized to sites of DNA replication. However, recently, both cyclin A and cyclin E have been implicated as regulators of centrosome replication, and it is unclear when and ...