Association between the Cyclin D1 G870A polymorphism and the susceptibility to and prognosis of upper aerodigestive tract squamous cell carcinomas: an updated meta-analysis

Aberrant Cyclin D1 splicing in cancer: from molecular mechanism to therapeutic modulation

Cyclin D1 (CCND1), a crucial mediator of cell cycle progression, possesses many mutation types with different mutation frequencies in human cancers. The G870A mutation is the most common mutation in CCND1, which produces two isoforms: full-length CCND1a and divergent C-terminal CCND1b. The dysregulation of the CCND1 isoforms is associated with multiple human cancers. Exploring the molecular mechanism of CCND1 isoforms has offer new insight for cancer treatment. On this basis, the alterations of CCND1 gene are described, including amplification, overexpression, and mutation, especially the G870A mutation. Subsequently, we review the characteristics of CCND1 isoforms caused by G870A mutation. Additionally, we summarize cis-regulatory elements, trans-acting factors, and the splice mutation involved in splicing regulation of CCND1. Furthermore, we highlight the function of CCND1 isoforms in cell cycle, invasion, and metastasis in cancers. Importantly, the clinical role of CCND1 isoforms is also discussed, particularly concerning prognosis, chemotherapy, and radiotherapy. Last, emphasis is given to the corrective strategies that modulate the cancerous CCND1 isoforms. Thus, it is highlighting significance of aberrant isoforms of CCND1 as targets for cancer therapy.

G870A Polymorphic Variants of CCND1 Gene and Cyclin D1 Protein Expression as Prognostic Markers in Laryngeal Lesions

CCND1 gene encodes Cyclin D1 protein, the alternations and overexpression of which are commonly observed in human cancers. Cyclin D1 controls G1-S transition in the cell cycle. The aim of the study was to assess utility of the genotyping and protein expression in predicting the susceptibility of transformation from normal tissue to precancerous laryngeal lesions (PLLs) and finally to laryngeal cancer (LC). Four hundred and thirty-five patients (101 with LC, 100 with PLLs and 234 healthy volunteers) were enrolled in the study. Cyclin D1 expression was examined by immunohistochemistry and G870A polymorphism of gene CCND1 by PCR-RFLP technique. We confirmed association between the A allele and risk of developing LC from healthy mucosa (p = 0.006). Significantly higher expression of Cyclin D1 was observed in LC compering with PLLs (p < 0.0001) and we found that it could be a predictive marker of shorter survival time. To sum up, in the study population CCND1 gene polymorphism A870G and Cyclin D1 expression have a significant impact on the risk of developing PLLs and LC, and, therefore, Cyclin D1 could be a useful marker for the prediction of survival time in LC, whereas CCND1 gene polymorphism does not have a direct impact on patients’ outcome.

PKC iota promotes cellular proliferation by accelerated G1/S transition via interaction with CDK7 in esophageal squamous cell carcinoma

Protein kinase C iota (PKCι) has been shown to play an important role in tumorigenesis of many cancers. It was reported that frequent amplification and overexpression of PKCi were correlated with resistance to anoikis in primary esophageal squamous cell carcinomas (ESCC). In this study, we clarified a novel role of PKCι on the cell cycle progression and proliferation in ESCC. Western blot and immunohistochemistry (IHC) analysis showed that the expression of PKCι was higher in ESCC tumor tissues and cell lines. Meanwhile, IHC stain revealed that PKCι was positively correlated with clinical pathologic variables such as tumor size, tumor grade, and tumor invasion, as well as ki67. Immunoprecipitation and immunofluorescence assay revealed that PKCι/CDK7 has the physical interaction and were co-located in the cell nucleus. And this direct interaction could increase the phosphorylation level of CDK7. In vitro studies such as starvation and refeeding assay along with PKCι-shRNA transfection assay demonstrated that PKCι expression promoted proliferation of ESCC cells. And knocking PKCi down by silencing RNA (siRNA) significantly caused cell cycle arrest at G0/G1 phase, decreased rate of colony formation, and alleviated cellular apoptosis. This research provide new insights into PKCi signaling to more deeply understand its cancer-promoting function in ESCC.