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Abnormal patterns of D-type cyclin expression and G1 regulation in human head and neck cancer
J Bartkova1, J Lukas, H Müller
1Danish Cancer Society, Division of Cancer Biology, Copenhagen.
Abstract:
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.
Insights
D-type cyclins, particularly cyclin D1, are key in head and neck cancer. This study shows cyclin D1 is often elevated in HNSCC, driving cell cycle progression and offering diagnostic potential.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- D-type cyclins are proto-oncogenic cell cycle regulators.
- Cyclin D1 gene amplification occurs in 30-50% of human head and neck squamous cell carcinoma (HNSCC).
Purpose of the Study:
- To investigate the role and expression of D-type cyclins in HNSCC pathogenesis.
- To assess the potential of immunohistochemistry for detecting cyclin D1 aberrations in clinical specimens.
Main Methods:
- Immunohistochemistry using a cyclin D1-specific mAb (DCS-6) on archival HNSCC specimens.
- Immunoblotting analysis of D-type cyclins in HNSCC-derived cell lines.
- Electroporation of neutralizing antibodies to assess cyclin function in cell cycle progression.
Main Results:
- Cyclin D1 positivity was detected in 69% of HNSCC patients (strong in 17%, moderate in 31%).
- HNSCC cell lines exhibited distinct D-type cyclin profiles (cyclin D1 only, D1/D3, or D1/D2/D3).
- Cyclin D1 was essential for cell cycle progression in all tested HNSCC cell lines; Cyclin D2 showed cooperative effects with cyclin D1 in UMSCC-1 cells.
Conclusions:
- Data support the oncogenic role of cyclin D1 in HNSCC.
- Immunohistochemical assessment of cyclin D1 aberrations is feasible in archival specimens.
- Elevated cyclin D1 or cooperative D-type cyclin effects may deregulate G1 control in HNSCC subsets.