MIAT lncRNA is overexpressed in breast cancer and its inhibition triggers senescence and G1 arrest in MCF7 cell line

Competing endogenous RNA (ceRNA) cross talk and language in ceRNA regulatory networks: A new look at hallmarks of breast cancer

Breast cancer (BC) is the most frequently occurring malignancy in women worldwide. Despite the substantial advancement in understanding the molecular mechanisms and management of BC, it remains the leading cause of cancer death in women. One of the main reasons for this obstacle is that we have not been able to find the Achilles heel for the BC as a highly heterogeneous disease. Accumulating evidence has revealed that noncoding RNAs (ncRNAs), play key roles in the development of BC; however, the involving of complex regulatory interactions between the different varieties of ncRNAs in the development of this cancer has been poorly understood. In the recent years, the newly discovered mechanism in the RNA world is "competing endogenous RNA (ceRNA)" which proposes regulatory dialogues between different RNAs, including long ncRNAs (lncRNAs), microRNAs (miRNAs), transcribed pseudogenes, and circular RNAs (circRNAs). In the latest BC research, various studies have revealed that dysregulation of several ceRNA networks (ceRNETs) between these ncRNAs has fundamental roles in establishing the hallmarks of BC development. And it is thought that such a discovery could open a new window for a better understanding of the hidden aspects of breast tumors. Besides, it probably can provide new biomarkers and potential efficient therapeutic targets for BC. This review will discuss the existing body of knowledge regarding the key functions of ceRNETs and then highlights the emerging roles of some recently discovered ceRNETs in several hallmarks of BC. Moreover, we propose for the first time the "ceRnome" as a new term in the present article for RNA research.

Long non-coding RNA CASC15 promotes tongue squamous carcinoma progression through targeting miR-33a-5p

Long non-coding RNAs (lncRNAs) have gained a lot of attention because they participate in several human disorders, including tumors. This study determined the role of LncRNA CASC15 (cancer susceptibility candidate 15) in the development of tongue squamous cell carcinoma (TSCC). Here, we identified that CASC15 expression was upregulated in TSCC samples and cell lines. We showed that overexpression of CASC15 promoted cell proliferation, cycle, and migration in TSCC. In addition, we revealed that miR-33a-5p expression was downregulated in TSCC tissues and cell lines. Moreover, we showed that the expression of CASC15 was negatively related with miR-33a-5p expression in TSCC tissues. Ectopic expression of miR-33a-5p suppressed cell proliferation, cycle, and migration in TSCC. Elevated expression of CASC15 suppressed miR-33a-5p expression and promoted ZEB1 expression in SCC4 cell. Ectopic expression of CASC15 promoted TSCC cell proliferation, cycle, and migration through targeting miR-33a-5p. These results suggested that lncRNA CASC15 and miR-33a-5p might be exploited as new markers of TSCC and were potential treatment targets for TSCC patients.

ALDH1 as a prognostic marker for lymph node metastasis in OSCC

Long-term survival in cases of head and neck squamous cell carcinoma, particularly oral squamous cell carcinoma (OSCC), remains a rare achievement in the field of clinical oncology. In recent years, the theory of cancer stem cells (CSCs) has emerged and been used to offer explanations for tumour recurrence and metastasis. The present aim was to investigate the role of aldehyde dehydrogenase 1 (ALDH1) as a CSC-marker for OSCC and to determine the role of p16^ink4a, which is also a surrogate marker of human papilloma virus (HPV), in the expression of ALDH1. The study cohort comprised of 186 surgically-treated cases of OSCC. The primaries were located in the oral cavity. The expression of the CSC marker (CSCM) ALDH1 was evaluated via immunohistochemistry (IHC) of a tissue microarray. HPV detection was performed by polymerase chain reaction and an HPV Array kit. Furthermore, the IHC expression of p16^ink4a was also analysed. Risk regression models as the Kruskal Wallis test was used to assess the association of CSCM and p16^ink4a expression with tumour size and lymph node metastasis, and cox proportional hazards were analysed. Additionally, coexpression of the markers ALDH1 and p16^ink4a was analysed with regard to associations with tumour classification. Overall, high expression of ALDH1 in lymph nodes was significantly associated with Union for International Cancer Control (UICC) stage IV (P=0.044) and T4 stage cancer (P=0.03). p16^ink4a positivity, in cases of HPV negativity, was associated with worse survival rate compared with that of the total cohort (P=0.048). Collectively the data indicate that ALDH1 expression may be suitable for detection of unfavourable prognosis in OSCC patients, based in part on its apparent role as a marker of metastasis. HPV status was not statistically predictive of patient outcome or CSCM expression; however, p16^ink4a remains a potential marker in HNSCC Further in vitro studies with ALDH1 and p16^ink4a should be performed to evaluate the expression of ALDH1 and HPV in cell culture and to clarify the role of ALDH1 as a marker for increased invasiveness of OSCC cells.

Long noncoding RNA MIAT regulates apoptosis and the apoptotic response to chemotherapeutic agents in breast cancer cell lines

The long noncoding RNA myocardial infarction associated transcript (MIAT) is involved in a number of diseases, including myocardial infarction and diabetic retinopathy. Emerging evidence suggests that MIAT expression levels are increased in different type of cancers, including breast cancer. In the present study, we further evaluated the role of MIAT in breast cancer and investigated the consequences of its silencing on breast cancer response to chemotherapeutic agents. Expression levels of MIAT mRNA in breast cancer were determined using TissueScan™ Breast Cancer cDNA Arrays. Breast cancer cell lines were transfected with MIAT specific siRNAs, with silencing confirmed using RT-qPCR and the effects on breast cancer cell survival and response to different apoptotic stimuli determined. MIAT transcript levels were significantly elevated in breast cancer samples. Such increase was specific to the early stages of the disease, ER, PR +ve, HER –ve, and triple negative breast cancer samples. Silencing of MIAT induced growth arrest and increased basal apoptosis. Reduced levels of MIAT augmented the apoptotic response of breast cancer cells to a wide range of apoptotic stimuli. Our results also showed that MIAT down-regulation was associated with a decrease in OCT4 mRNA, suggesting the existence of a MIAT/OCT4 regulatory loop, similar to that observed in malignant mature B cells. Taken together with the recent demonstration of oncogene characteristics, our observations suggest that MIAT plays an important role in breast tumorigenesis. Strategies to decrease MIAT expression levels may improve sensitivity to therapy in breast cancer by enhancing the apoptotic responses to conventional chemotherapies.