We demonstrate in this paper that CDK4 which is a G1 phase specific cell cycle regulator and catalytic subunit of D-type cyclins has oncogenic activity similar to D-type cyclins themselves and is able to provoke focus formation when cotransfected with activated Ha-ras into primary rat embryo fibroblasts. Surprisingly, using two different mutants we show that CDK4's ability to bind to p16INK4a and not its kinase activity is important for its transforming potential. In addition, p16INK4a but not a mutant form that is found in human tumours can completely abrogate focus formation by CDK4 suggesting that CDK4 can malignantly transform cells by sequestering p16INK4a or other CKIs. We demonstrate that both cyclin D1 and CDK4 functionally depend on active Myc to exert their potential as oncogenes and vice versa that the transforming ability of Myc requires functional cyclin D/CDK complexes. Moreover, we find that p16INK4a and the Rb related protein p107 which releases Myc after phosphorylation by cyclin D1/CDK4 efficiently block Myc's activity as a transcriptional transactivator and as an oncogene. We conclude that both p16INK4a and cyclin D/CDK4 complexes are upstream regulators of Myc and directly govern Myc function in transcriptional transactivation and transformation via the pocket protein p107.
- MeSH
- aktivace transkripce MeSH
- buňky 3T3 MeSH
- cyklin D1 MeSH
- cyklin-dependentní kinasa 4 MeSH
- cyklin-dependentní kinasy fyziologie MeSH
- cykliny fyziologie MeSH
- geny myc fyziologie MeSH
- HeLa buňky MeSH
- inhibitor p16 cyklin-dependentní kinasy MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- myši MeSH
- nádorová transformace buněk * MeSH
- onkogenní proteiny fyziologie MeSH
- potkani inbrední F344 MeSH
- protoonkogenní proteiny * MeSH
- retinoblastomový protein fyziologie MeSH
- transportní proteiny fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
D-type cyclins are proto-oncogenic cell cycle regulators implicated in the pathogenesis of several types of cancer. Amplification of the cyclin D1 gene has been described in 30-50% of human head and neck squamous cell carcinoma (HNSCC). Using immunohistochemistry on archival specimens of human HNSCC and a mAb DCS-6, which is specific for cyclin D1, strong positivity was found in nuclei of 9 (17%) of 52, a moderately elevated signal in 16 (31%) of 52, and weak staining comparable with normal tissues in 27 (52%) of 52 patients. Immunoblotting analysis of five HNSCC-derived cell lines showed three distinct spectra of D-type cyclin proteins: cyclin D1 only (in UMSCC-2 and UMSCC-22b cell lines with 11q13 amplification), cyclins D1 and D3 (in HN5 and HN6), or cyclins D1, D2, and D3 (in UMSCC-1). Electroporation of neutralizing antibodies demonstrated requirement for cyclin D1 in cell cycle progression of all five HNSCC cell lines. Cyclin D2 was essential and showed a cooperative effect with cyclin D1 in positive regulation of G1 in UMSCC-1 cells. These data are consistent with the proposed oncogenic role of cyclin D1 in HNSCC and open up the way for immunohistochemical assessment of cyclin D1 aberrations in archival clinical specimens. It is also suggested that excessive levels of cyclin D1 alone or cooperative effects of several D-type cyclin proteins may lead to deregulation of G1 control in distinct subsets of human HNSCC. These results are discussed in the context of possible functional redundancy of D-type cyclins and the role of the D-type cyclin/p16-CDKN2/pRB pathway in tumorigenesis.
- MeSH
- cyklin D1 MeSH
- cyklin D2 MeSH
- cykliny analýza fyziologie MeSH
- G1 fáze * fyziologie MeSH
- imunohistochemie MeSH
- lidé MeSH
- nádory hlavy a krku chemie patologie MeSH
- onkogenní proteiny analýza fyziologie MeSH
- spinocelulární karcinom chemie patologie MeSH
- zalévání tkání do parafínu MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
D-type cyclins, in association with the cyclin-dependent kinases Cdk4 or Cdk6, promote progression through the G1 phase of the cell cycle by phosphorylating the retinoblastoma protein (RB). The activities of Cdk4 and Cdk6 are constrained by inhibitors such as p16, the product of the CDKN2 gene on human chromosome 9p21 (refs 12-14). The frequent deletion or mutation of CDKN2 in tumour cells suggests that p16 acts as a tumour suppressor. We show that wild-type p16 arrests normal diploid cells in late G1, whereas a tumour-associated mutant of p16 does not. Significantly, the ability of p16 to induce cell-cycle arrest is lost in cells lacking functional RB, including primary fibroblasts from Rb-/- mouse embryos. Thus, loss of p16, overexpression of D-cyclins and loss of RB have similar effects on G1 progression, and may represent a common pathway to tumorigenesis.
- MeSH
- buněčný cyklus * fyziologie MeSH
- cyklin D1 MeSH
- cyklin-dependentní kinasa 4 MeSH
- cyklin-dependentní kinasa 6 MeSH
- cyklin-dependentní kinasy * MeSH
- cykliny fyziologie MeSH
- Escherichia coli MeSH
- G1 fáze fyziologie MeSH
- inhibitor p16 cyklin-dependentní kinasy MeSH
- klonování DNA MeSH
- kultivované buňky MeSH
- lidé MeSH
- mikroinjekce MeSH
- mutace MeSH
- myši inbrední BALB C MeSH
- myši MeSH
- nádorové buňky kultivované MeSH
- onkogenní proteiny fyziologie MeSH
- protein-serin-threoninkinasy antagonisté a inhibitory MeSH
- protoonkogenní proteiny * MeSH
- rekombinantní proteiny metabolismus MeSH
- retinoblastomový protein * fyziologie MeSH
- transportní proteiny fyziologie genetika MeSH
- tumor supresorové geny * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
To explore regulation and function of cyclin D2, a candidate cell cycle-regulatory proto-oncogene, we examined subcellular localisation, cell type- and cell cycle-dependent expression, and requirement of cyclin D2 protein for G1 progression, in a panel of 40 human normal and cancer cell types. Except for lymphoid cells and sarcoma cell lines, expression of cyclin D2 was considerably more restricted than that of cyclin D1, whereas both D-type cyclin proteins were low or undetectable in cells lacking functional retinoblastoma gene product. In G1 cells, the cyclin D2 protein was more resistant to extraction and localised predominantly to nuclei, whereas it became more soluble and distributed in both nuclei and cytoplasm from G1/S transition onwards. Centrifugal elutriation and multiparameter flow cytometry analyses of several cell types showed moderate cell cycle oscillation with maximum levels of the cyclin D2 protein reached in late G1. Microinjection and/or electroporation of antibodies to cyclin D2 during G1 arrested the cyclin D2-expressing lymphocytes, breast myoepithelium, and U-2-OS sarcoma cells in G1 phase, whereas cyclin D2-negative cell types were unaffected by such treatment. Consistent with the putative proto-oncogenic role of cyclin D2 in specific cell types, our data show that this G1 cyclin has properties closely resembling those of cyclin D1, including the essential positive role in regulation of G1.
- MeSH
- buněčné linie MeSH
- cyklin D1 MeSH
- cyklin D2 MeSH
- cykliny fyziologie imunologie MeSH
- G1 fáze * fyziologie MeSH
- lidé MeSH
- monoklonální protilátky imunologie MeSH
- myši inbrední BALB C MeSH
- myši MeSH
- nádorové buňky kultivované MeSH
- nukleoproteiny fyziologie imunologie MeSH
- onkogenní proteiny fyziologie MeSH
- subcelulární frakce metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
In this paper we describe how research on the mouse mammary tumor virus model of breast cancer resulted in the identification of an amplified region of DNA on human chromosome 11 band q13. This amplification occurs in approximately 15% of primary breast cancers. Several candidate oncogenes map within the amplicon but by analysing expression of these genes a strong case can be made for a role for cyclin D1 in tumorigenesis. Immunohistochemical staining indicates that cyclin D1 is expressed at elevated levels in around 40% of breast cancers, including those with the 11q13 amplification. The potential function of cyclin D1 as a regulator of early cell division cycle events would be consistent with a role in neoplasia.
- MeSH
- amplifikace genu MeSH
- cyklin D1 MeSH
- cykliny fyziologie MeSH
- lidé MeSH
- lidské chromozomy, pár 11 genetika MeSH
- nádory prsu genetika MeSH
- onkogenní proteiny fyziologie MeSH
- Southernův blotting MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
