Involvement of elevated expression of multiple cell-cycle regulator, DTL/RAMP (denticleless/RA-regulated nuclear matrix associated protein), in the growth of breast cancer cells

Abstract

To investigate the detailed molecular mechanism of mammary carcinogenesis and discover novel therapeutic targets, we previously analysed gene expression profiles of breast cancers. We here report characterization of a significant role of DTL/RAMP (denticleless/RA-regulated nuclear matrix associated protein) in mammary carcinogenesis. Semiquantitative RT-PCR and northern blot analyses confirmed upregulation of DTL/RAMP in the majority of breast cancer cases and all of breast cancer cell lines examined. Immunocytochemical and western blot analyses using anti-DTL/RAMP polyclonal antibody revealed cell-cycle-dependent localization of endogenous DTL/RAMP protein in breast cancer cells; nuclear localization was observed in cells at interphase and the protein was concentrated at the contractile ring in cytokinesis process. The expression level of DTL/RAMP protein became highest at G 1 /S phases, whereas its phosphorylation level was enhanced during mitotic phase. Treatment of breast cancer cells, T47D and HBC4, with small-interfering RNAs against DTL/RAMP effectively suppressed its expression and caused accumulation of G 2 /M cells, resulting in growth inhibition of cancer cells. We further demonstrate the in vitro phosphorylation of DTL/ RAMP through an interaction with the mitotic kinase, Aurora kinase-B (AURKB). Interestingly, depletion of AURKB expression with siRNA in breast cancer cells reduced the phosphorylation of DTL/RAMP and decreased the stability of DTL/RAMP protein. These findings imply important roles of DTL/RAMP in growth of breast cancer cells and suggest that DTL/RAMP might be a promising molecular target for treatment of breast cancer.

The Neddylation Inhibitor Pevonedistat (MLN4924) Suppresses and Radiosensitizes Head and Neck Squamous Carcinoma Cells and Tumors

“…Previous studies demonstrated that the CRL4 substrate receptor CDT2 is overexpressed in various human cancers (27,(39)(40)(41)(42). This study extends this observation to HNSCC, where CDT2 is found to be significantly overexpressed in HNSCC from various tissues.…”

“…CDT2 expression is elevated in a number of human malignancies, including breast, gastric, liver, brain, and skin cancers (27,(39)(40)(41). In addition, the DTL gene encoding CDT2 is amplified in a subset of Ewing carcinoma (42).…”

Involvement of C12orf32 overexpression in breast carcinogenesis

“…Through the genome-wide expression analysis of a large number of microdissected clinical cancer materials, we have identified dozens of genes that function as oncogenes in the process of development and/or progression of breast cancer (10)(11)(12)(13)(14)(15)(16)(17), bladder cancer (18,19), synovial sarcoma (20,21), testicular seminoma (22), and renal cell carcinoma (23,24). Such molecules are considered to be candidate molecular targets for development of new therapeutic modalities.…”

Regulation of TGF-β signaling, exit from the cell cycle, and cellular migration through cullin cross-regulation: SCF-FBXO11 turns off CRL4-Cdt2

“…On the other hand, Cdt2 may function as a tumor oncogene, because it exhibits high expression in multiple human cancers, including liver, breast, gastric, and colon cancers, and its elevated expression correlates positively with advanced disease state, metastasis, and poor patient survival. [58][59][60][61] In addition, the Cdt2 gene was amplified in a subset of Ewing sarcomas. 62 However, it is unclear how Cdt2 may exhibit its oncogenic activity, although its ability to assemble CRL4 Cdt2 E3 ubiquitin ligase and promote the polyubiquitylation and degradation of p21 as well as its ability to monoubiquitylate PCNA and regulate TLS in proliferating cells may play an Cdt2 to promote exit from the cell cycle.…”