Role of Cell Cycle Control and Cyclin-Dependent Kinases in Breast Cancer

2002 ◽  
Vol 15 (1) ◽  
pp. 33-52
Author(s):  
Adrian M. Senderowicz
Author(s):  
Shamim Mushtaq

Uninhibited proliferation and abnormal cell cycle regulation are the hallmarks of cancer. The main role of cyclin dependent kinases is to regulate the cell cycle and cell proliferation. These protein kinases are frequently down regulated or up regulated in various cancers. Two CDK family members, CDK 11 and 12, have contradicting views about their roles in different cancers. For example, one study suggests that the CDK 11 isoforms, p58, inhibits growth of breast cancer whereas, the CDK 11 isoform, p110, is highly expressed in breast tumor. Studies regarding CDK 12 show variation of opinion towards different parts of the body, however there is a consensus that upregulation of cdk12 increases the risk of breast cancer. Hence, CDK 11 and CDK 12 need to be analyzed to confirm their mechanism and their role regarding therapeutics, prognostic value, and ethnicity in cancer. This article gives an outline on both CDKs of information known up to date from Medline, PubMed, Google Scholar and Web of Science search engines, which were explored and thirty relevant researches were finalized.


1994 ◽  
Vol 127 (2) ◽  
pp. 467-478 ◽  
Author(s):  
J P Tassan ◽  
S J Schultz ◽  
J Bartek ◽  
E A Nigg

The activity of cyclin-dependent kinases (cdks) depends on the phosphorylation of a residue corresponding to threonine 161 in human p34cdc2. One enzyme responsible for phosphorylating this critical residue has recently been purified from Xenopus and starfish. It was termed CAK (for cdk-activating kinase), and it was shown to contain p40MO15 as its catalytic subunit. In view of the cardinal role of cdks in cell cycle control, it is important to learn if and how CAK activity is regulated during the somatic cell cycle. Here, we report a molecular characterization of a human p40MO15 homologue and its associated CAK activity. We have cloned and sequenced a cDNA coding for human p40MO15, and raised specific polyclonal and monoclonal antibodies against the corresponding protein expressed in Escherichia coli. These tools were then used to demonstrate that p40MO15 protein expression and CAK activity are constant throughout the somatic cell cycle. Gel filtration suggests that active CAK is a multiprotein complex, and immunoprecipitation experiments identify two polypeptides of 34 and 32 kD as likely complex partners of p40MO15. The association of the three proteins is near stoichiometric and invariant throughout the cell cycle. Immunocytochemistry and biochemical enucleation experiments both demonstrate that p40MO15 is nuclear at all stages of the cell cycle (except for mitosis, when the protein redistributes throughout the cell), although the p34cdc2/cyclin B complex, one of the major purported substrates of CAK, occurs in the cytoplasm until shortly before mitosis. The absence of obvious changes in CAK activity in exponentially growing cells constitutes a surprise. It suggests that the phosphorylation state of threonine 161 in p34cdc2 (and the corresponding residue in other cdks) may be regulated primarily by the availability of the cdk/cyclin substrates, and by phosphatase(s).


Cancers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 5343
Author(s):  
Joseph T. Decker ◽  
Jeffrey A. Ma ◽  
Lonnie D. Shea ◽  
Jacqueline S. Jeruss

TGFβ signaling enacts tumor-suppressive functions in normal cells through promotion of several cell regulatory actions including cell-cycle control and apoptosis. Canonical TGFβ signaling proceeds through phosphorylation of the transcription factor, SMAD3, at the C-terminus of the protein. During oncogenic progression, this tumor suppressant phosphorylation of SMAD3 can be inhibited. Overexpression of cyclins D and E, and subsequent hyperactivation of cyclin-dependent kinases 2/4 (CDKs), are often observed in breast cancer, and have been associated with poor prognosis. The noncanonical phosphorylation of SMAD3 by CDKs 2 and 4 leads to the inhibition of tumor-suppressive function of SMAD3. As a result, CDK overactivation drives oncogenic progression, and can be targeted to improve clinical outcomes. This review focuses on breast cancer, and highlights advances in the understanding of CDK-mediated noncanonical SMAD3 phosphorylation. Specifically, the role of aberrant TGFβ signaling in oncogenic progression and treatment response will be examined to illustrate the potential for therapeutic discovery in the context of cyclins/CDKs and SMAD3.


Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3075
Author(s):  
Jinyuan Duan ◽  
Wenzhu Li ◽  
Xin Shu ◽  
Bing Yang ◽  
Xiangwei He ◽  
...  

Reversible phosphorylation has emerged as an important mechanism for regulating proteasome function in various physiological processes. Essentially all proteasome phosphorylations characterized thus far occur on proteasome holoenzyme or subcomplexes to regulate substrate degradation. Here, we report a highly conserved phosphorylation that only exists on the unassembled α5 subunit of the proteasome. The modified residue, α5-Ser16, is within a SP motif typically recognized by cyclin-dependent kinases (CDKs). Using a phospho-specific antibody generated against this site, we found that α5-S16 phosphorylation is mitosis-specific in both yeast and mammalian cells. Blocking this site with a S16A mutation caused growth defect and G2/M arrest of the cell cycle. α5-S16 phosphorylation depends on CDK1 activity and is highly abundant in some but not all mitotic cells. Immunoprecipitation and mass spectrometry (IP-MS) studies identified numerous proteins that could interact with phosphorylated α5, including PLK1, a key regulator of mitosis. α5–PLK1 interaction increased upon mitosis and could be facilitated by S16 phosphorylation. CDK1 activation downstream of PLK1 activity was delayed in S16A mutant cells, suggesting an important role of α5-S16 phosphorylation in regulating PLK1 and mitosis. These data have revealed an unappreciated function of “exo-proteasome” phosphorylation of a proteasome subunit and may bring new insights to our understanding of cell cycle control.


2021 ◽  
Vol 13 (1) ◽  
pp. 17-29
Author(s):  
Emann M Rabie ◽  
Sherry X Zhang ◽  
Andreas P Kourouklis ◽  
A Nihan Kilinc ◽  
Allison K Simi ◽  
...  

Abstract Metastasis, the leading cause of mortality in cancer patients, depends upon the ability of cancer cells to invade into the extracellular matrix that surrounds the primary tumor and to escape into the vasculature. To investigate the features of the microenvironment that regulate invasion and escape, we generated solid microtumors of MDA-MB-231 human breast carcinoma cells within gels of type I collagen. The microtumors were formed at defined distances adjacent to an empty cavity, which served as an artificial vessel into which the constituent tumor cells could escape. To define the relative contributions of matrix degradation and cell proliferation on invasion and escape, we used pharmacological approaches to block the activity of matrix metalloproteinases (MMPs) or to arrest the cell cycle. We found that blocking MMP activity prevents both invasion and escape of the breast cancer cells. Surprisingly, blocking proliferation increases the rate of invasion but has no effect on that of escape. We found that arresting the cell cycle increases the expression of MMPs, consistent with the increased rate of invasion. To gain additional insight into the role of cell proliferation in the invasion process, we generated microtumors from cells that express the fluorescent ubiquitination-based cell cycle indicator. We found that the cells that initiate invasions are preferentially quiescent, whereas cell proliferation is associated with the extension of invasions. These data suggest that matrix degradation and cell proliferation are coupled during the invasion and escape of human breast cancer cells and highlight the critical role of matrix proteolysis in governing tumor phenotype.


BioEssays ◽  
1996 ◽  
Vol 18 (3) ◽  
pp. 183-190 ◽  
Author(s):  
Stephen E. Kearsey ◽  
Domenico Maiorano ◽  
Eddie C. Holmes ◽  
Ivan T. Todorov

2021 ◽  
Vol 11 ◽  
Author(s):  
Qianxue Wu ◽  
Xin Tang ◽  
Wenming Zhu ◽  
Qing Li ◽  
Xiang Zhang ◽  
...  

BackgroundPatients with triple-negative breast cancer (TNBC) have poor overall survival. The present study aimed to investigate the potential prognostics of TNBC by analyzing breast cancer proteomic and transcriptomic datasets.MethodsCandidate proteins selected from CPTAC (the National Cancer Institute’s Clinical Proteomic Tumor Analysis Consortium) were validated using datasets from METABRIC (Molecular Taxonomy of Breast Cancer International Consortium). Kaplan-Meier analysis and ROC (receiver operating characteristic) curve analysis were performed to explore the prognosis of candidate genes. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis were performed on the suspected candidate genes. Single-cell RNA-seq (scRNA-seq) data from GSE118389 were used to analyze the cell clusters in which OBFC2A (Oligosaccharide-Binding Fold-Containing Protein 2A) was mainly distributed. TIMER (Tumor Immune Estimation Resource) was used to verify the correlation between OBFC2A expression and immune infiltration. Clone formation assays and wound healing assays were used to detect the role of OBFC2A expression on the proliferation, invasion, and migration of breast cancer cells. Flow cytometry was used to analyze the effects of silencing OBFC2A on breast cancer cell cycle and apoptosis.ResultsSix candidate proteins were found to be differentially expressed in non-TNBC and TNBC groups from CPTAC. However, only OBFC2A was identified as an independently poor prognostic gene marker in METABRIC (HR=3.658, 1.881-7.114). And OBFC2A was associated with immune functions in breast cancer. Biological functional experiments showed that OBFC2A might promote the proliferation and migration of breast cancer cells. The inhibition of OBFC2A expression blocked the cell cycle in G1 phase and inhibited the transformation from G1 phase to S phase. Finally, downregulation of OBFC2A also increased the total apoptosis rate of cells.ConclusionOn this basis, OBFC2A may be a potential prognostic biomarker for TNBC.


2008 ◽  
Vol 10 (3) ◽  
Author(s):  
Elizabeth M Azzato ◽  
Kristy E Driver ◽  
Fabienne Lesueur ◽  
Mitul Shah ◽  
David Greenberg ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document