Cell cycle control in breast cancer cells

Abstract

In breast cancer, cyclins D1 and E and the cyclin-dependent kinase inhibitors p21 (Waf1/Cip1)and p27 (Kip1) are important in cell-cycle control and as potential oncogenes or tumor suppressor genes. They are regulated in breast cancer cells following mitogenic stimuli including activation of receptor tyrosine kinases and steroid hormone receptors, and their deregulation frequently impacts on breast cancer outcome, including response to therapy. The cyclindependent kinase inhibitor p16 (INK4A) also has a critical role in transformation of mammary epithelial cells. In addition to their roles in cell cycle control, some of these molecules, particularly cyclin D1, have actions that are not mediated through regulation of cyclin-dependent kinase activity but may be important for loss of proliferative control during mammary oncogenesis. J. Cell. Biochem. 97: 261-274, 2006. ß 2005 Wiley-Liss, Inc.Key words: cyclin D1; cyclin E; CDK inhibitors; steroid hormones; receptor tyrosine kinasesThe identification of cyclins in the 1980s revolutionized the cell-cycle field and the subsequent functional analysis of cyclins and CDKs provided an unprecedented opportunity to gain a molecular understanding of the cell-cycle machinery, its regulation in normal physiology, and its deregulation during oncogenesis. In the context of breast cancer, cyclins D1 and E were quickly established as early response genes following treatment with known regulators of proliferation including steroids and mitogenic growth factors. Complementary studies showed that these cyclins were deregulated in breast cancer. As the complexity of regulation of CDK activity was revealed, it also became apparent that the cell-cycle machinery was deregulated at multiple levels in breast cancer cells. There is now so much information on the regulation and function of the cell-cycle machinery in breast cancer cells that we have necessarily been selective in the areas covered in this review. We have concentrated here on the cyclins and CDK inhibitors that have been most extensively studied as regulators of the cell cycle in breast cancer cells, as putative mammary oncogenes or tumor suppressor genes, and as potential markers of therapeutic response or outcome: cyclins D1 and E1, and the CDK inhibitors p27 (Kip1), p21 (WAF1/Cip1), and p16 (INK4A). Although this review focuses on cyclins and CDK inhibitors, there are other cell-cycle regulators of known importance in breast cancer, notably the proto-oncogene c-Myc, which has recently been reviewed in this context [Jamerson et al., 2004]. CELL-CYCLE CONTROL MECHANISMSThe cell cycle comprises a series of tightly controlled events that drive the replication of DNA and cell division. It is divided into several phases: preparation for (G 1 phase), and execution of, DNA synthesis (S phase), a second gap phase (G 2 ), and mitosis (M). Quiescence (G 0 ) is a ß 2005 Wiley-Liss, Inc.

Targeting triple-negative breast cancer cells with 6,7-bis(hydroxymethyl)-1H,3H-pyrrolo[1,2-c]thiazoles

“…As can be observed in Figure 7, 3 induces a blockade in the G0/G1 phase in HCC1806 cell line (p=0.001), but has no effect in the other phases of the cell cycle, indicating a state of quiescence where cells stop dividing [13]. Similarly to treatment in the MCF7 cell line, 9b produced a decreased population of HCC1806 cells in the G0/G1 (p<0.001) and an accentuated accumulation of cells in the S phase (p<0.001) and in the pre-G0 phase (p=0.011).…”

Enhanced Expression of Rab27A Gene by Breast Cancer Cells Promoting Invasiveness and the Metastasis Potential by Secretion of Insulin-Like Growth Factor-II

“…MMPs are a family of zinc-dependent neutral endopeptidases that play a key role in degrading the extracellular matrix and basement membrane in various cancers and therefore promotes metastasis and angiogenesis (42,46). Increased numbers of blood vessels and hence increased angiogenic activity are essential for the growth and metastasis of cancer (47).…”

Impaired p53 function leads to centrosome amplification, acquired ERα phenotypic heterogeneity and distant metastases in breast cancer MCF-7 xenografts

“…Likewise, cyclin E/cdk2 and cyclin A/cdk2 complexes are responsible for the G 1 /S transition and onset of DNA replication, respectively (Hwang and Clurman, 2005;Mailand and Diffley, 2005). Aberrant expression of cyclins is linked to breast cancer development and progression (Bindels et al, 2002;Akli et al, 2004;Caldon et al, 2006). While cyclin D1 overexpression is generally associated with an ERapositive phenotype and favorable clinical outcome, deregulation of cyclin E and A is linked to induction of centrosome amplification, aneuploidy, loss of ERa and poor outcome (Bindels et al, 2002;Span et al, 2003;Joe et al, 2005).…”