Abstract SY34-03: Braking the cycle: Inhibition of the cyclin D-Cdk4/6 pathway in breast cancer

Prognostic Utility of Cyclin D1 in Invasive Breast Carcinoma

Invasive breast carcinoma is the most common cancer among women worldwide. Increase in early detection of breast carcinoma by different diagnostic modalities led to decrease in cancer-related mortality and morbidity. Multiple factors and genes are implicated in breast cancer pathogenesis. Cyclin D1 is an important cell cycle regulatory protein involved in carcinogenesis of various human cancers including breast cancer. Aims of the present study were to evaluate the prognostic importance of cyclin D1 expression in invasive breast carcinoma and its correlation with other prognostic and predictive factors. Patients undergoing mastectomy for breast carcinoma were selected from January 2016 to June 2017 in a tertiary care hospital. Clinical history including demographic parameters was collected in the study pro forma. Immunohistochemical staining for ER, PgR, HER2 and cyclin D1 was performed on all cases. The clinicopathological parameters like age, tumour size, histologic grade, histological type, lymphovascular invasion, axillary lymph node metastasis, ER, PgR and HER2 status were compared and correlated with cyclin D1 expression. Cyclin D1 expression found in 60% cases of breast carcinoma. Expression of cyclin D1 showed a highly significant correlation with histological grade (p = 0.000). Cyclin D1 expression showed significant correlation (p = 0.000) with molecular subtypes. There was also significant correlation between cyclin D1 expression and ER (p = 0.000) and PgR (p = 0.010) status. This study revealed significant cyclin D1 expression in low grade, well-differentiated breast cancer. Therefore, we found cyclin D1 as a favourable prognostic marker in breast carcinoma.

EZH2-mediated suppression of lncRNA-LET promotes cell apoptosis and inhibits the proliferation of post-burn skin fibroblasts

Although the upregulation of enhancer of zeste homolog 2 (EZH2) expression and downregulation of long non-coding RNA (lncRNA) LET expression are known to be associated with cell apoptosis and proliferation, little is known about the interaction of EZH2 with lncRNA LET. The present study aimed to investigate the interaction of EZH2 and lncRNA LET, and the mechanism of human dermal fibroblast (HDF) proliferation and apoptosis. Tissue samples from 33 burn patients with second- and third-degree burns and 8 controls were collected. mRNA was extracted from the burn tissues for analysis. Isolated primary HDFs were treated with heat or transfected with LET overexpression vectors, and the cell functions and associated proteins in the HDFs were analyzed. Decreased lncRNA LET expression was detected in burn tissues compared with normal skin. Heat-treated HDFs exhibited a reduction in lncRNA LET expression and increase in EZH2 expression. LET gain-of-function experiments in primary HDFs revealed increases in cell proliferation, the proportion of cells in the S stage, and cyclin D1 and cyclin-dependent kinase 4 (CDK4) expression, and reductions in the percentage of apoptotic cells, the Bax/Bcl-2 ratio and caspase-3 expression. RNA immunoprecipitation and chromatin immunoprecipitation assays demonstrated the interaction of ZH2 with lncRNA LET, and of EZH2 with H3K27me3 in HDFs. Furthermore, a negative correlation between lncRNA LET and EZH2 expression was identified. It may be concluded that increased lncRNA-LET expression promoted cell proliferation and inhibited cell apoptosis via the cyclin D1-CDK4 and Bax/Bcl-2/caspase-3 signaling pathways, respectively. Furthermore, the inhibition of lncRNA LET may be regarded as an option for use in the healing of burns.