Abnormal cell cycle regulation in malignancy.
The cell cycle consists of an initial growth phase (G1), DNA replication (S), a gap phase (G2), and mitosis (M), after which the cell may differentiate or enter the resting state (G0). The cycle is driven by a number of positive and negative regulatory phosphorylation and dephosphorylation events, involving protein kinases, protein phosphatases, cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitors, that ultimately impinge on the activity of transcription factors. Unreplicated or damaged DNA blocks the progression of the cell cycle at checkpoints, including a late G1 checkpoint regulated by the dephosphorylated retinoblastoma protein and a late G2 checkpoint regulated by the phosphorylation of cyclin-dependent kinase 1 complexed with cyclin B. Many cell cycle regulator genes may be considered proto-oncogenes or tumor suppressor genes, and point mutations, amplifications, deletions, or rearrangements involving their loci, particularly those in the "RB pathway," are associated with various tumors. A number of molecular techniques may be used to detect genomic alterations or posttranscriptional modifications, but immunohistochemistry remains the most common method to determine expression levels of a regulatory protein. Multivariate analysis of the usefulness in prognosis has been applied most often for the general proliferation antigen Ki-67.
Department of Pathology, Lund University Hospital, Sweden.
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M
Dictor
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Ehinger
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Mertens
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Akervall
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J
Wennerberg
D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D003362:Cost-Benefit Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005821:Genetic Techniques / Q000191:economics; D006801:Humans; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D004273:DNA, Neoplasm