Cycline D1

expression in mantle cell lymphomas. Cyclin D1 is negative for marginal zone lymphoma and other B cell type lymphomas.

Cyclin D1 plays a central role in the G1-S transition of the cell cycle. Dysregulated cyclin D1 expression plays a crucial pathogenetic role in many different tumors. A dysregulated cyclin D1 expression plays a decisive pathogenetic role in many different tumors. Especially in (cutaneous) B-cell lymphomas (mantle cell lymphoma, multiple myeloma). Furthermore, also in malignant melanoma, gastric carcinoma, carcinomas of the head and neck region as well as of the breast and intestine. The overexpression can be the result of gene amplification (e.g. in multiple myeloma and carcinomas), chromosomal translocation in mantle cell lymphoma (t11;14)(q13;q32) or stabilization at the RNA or protein level.

Cyclin D1 can be assigned the following functions:

• Activation of cyclin-dependent kinases 4 and 6 (CDK4/ CDK6). These take an important role in the transition from G1 to S phase in the cell cycle.
• Cyclin D1 inhibits the inhibitory function of the p21Cip1 and p27Kip1 proteins by intercepting them, thus accelerating the G1 phase in the cell cycle.
• Furthermore, cyclin D1 is able to alter the activity of various transcription factors independently of the cyclin-dependent kinases CDK4 or CDK6. transcription factors. The transcription factors affected include thyroid hormone, estrogen and androgen receptors as well as DMP1, STAT3 and others.

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4. Karim RZ et al (200) Reduced p16 and increased cyclin D1 and pRb expression are correlated with progression in cutaneous melanocytic tumors. Int J Surg Pathol 17:361-367.
5. Shen Yet al (2014) Cyclin D1 expression in Bowen's disease and cutaneous squamous cell carcinoma. Mol Clin Oncol 2:545-548.