Relation between the circular and linear form of the Elongator Acetyltransferase Complex Subunit 3 in the progression of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer (BC) that hardly responds to common treatment. Recent studies show that circ-ELP3 (Elongator Acetyltransferase Complex Subunit 3 or hsa-circ-0001785) is involved in the pathogenesis of several malignancies. The present study aimed to evaluate the possible role of this circRNA in the progression of TNBC cells and the possible relation between the circular and linear forms of the ELP3. We evaluated the circ-ELP3 and its host gene expression level in clinical samples and breast cancer cell lines. Using an expression vector, hsa-circ-0001785 was upregulated to investigate its role on cancer cell progression. After a transient transfection, we evaluated possible alterations in the cell cycle progression, cell viability, and cell proliferation. Quantitative real-time polymerase chain reaction analyses verified that circ-ELP3 and its host gene were significantly upregulated in TNBC tissues and breast cancer cells. Overexpression of circ-ELP3 markedly increases the cell viability and proliferation and also the formation of colonies in transfected cells compared to the controls. Briefly, our results showed that Circ-ELP3 and its host gene were significantly upregulated in TNBC. Circ-ELP3 is involved in TNBC progression and may exert its effects by indirectly regulating of ELP3 expression.

MiR-646 prevents proliferation and progression of human breast cancer cell lines by suppressing HDAC2 expression.

BACKGROUND: Breast cancer is a type of cancer with a high incidence and mortality rate worldwide. Change in epigenetic mechanisms enhances cancer cell progression. Histon deacetylase 2 (HDAC2) was found to act as a potential oncogene in different malignancies. For better understanding the mechanisms related to breast cancer development, we investigated the role of HDAC2 in breast cancer and the inhibitory effect of miR-646 on this oncogene. METHODS: A total of thirty cancerous tissues and 30 adjacent non-cancerous specimens and also three breast cancer cell lines were enrolled in the study. Quantitative reverse transcriptase PCR (qRT-PCR) was employed to detect the HDAC2 and miR-646 expression level in the studied samples. The biological roles of HDAC2 and miR-646 were investigated through manipulating the expression level of HDAC2 or miR-646 in breast cancer cells. Finally, we evaluated whether the HDAC2 is a direct target for miR-646. RESULTS: In this study, we found HDAC2 is significantly upregulated in cancerous specimens and cell lines compared to non-cancerous tissues and normal cell line. On the other hand, miR-646 expression was decreased in clinical specimens and breast cancer cells compared to non-cancerous samples. Knocking out of the HDAC2 and overexpression of miR-646 inhibited breast cancer cell growth but promoted cell death, while untreated groups showed inverse results. Furthermore, we showed that in the breast cancer cells, miR-646 regulates the progression and proliferation by suppressing HDAC2. CONCLUSION: Taken together, our study identified a miR-646/HDAC2 regulatory function in the breast cancer development and introduced a therapeutically target for breast cancer.

Association of HDAC8 Expression with Pathological Findings in Triple Negative and Non-Triple Negative Breast Cancer: Implications for Diagnosis.

Background: Previous data have shown the tumorigenicity roles of histone deacetylase 8 (HDAC 8) in breast cancer. More recently, the oncogenic effects of this molecule have been revealed in triple negative breast cancer (TNBC). The present study aimed to determine the diagnostic value of HDAC8 for the differentiation of TNBC from nTNBC tumors. Methods: A total of 50 cancerous and normal adjacent tumor specimens were obtained, and the clinical and pathological findings of studied subjects were recorded. The expression of HDAC8 gene was determined by qRT-PCR. Also, immunohistochemical staining was performed on tissue samples. Results: Our results showed that the expression of HDAC8 in breast cancer tissues was significantly higher than the normal adjacent tissues (p = 0.0011). HDAC8 expression was also observed to be higher in TNBC patients than nTNBC group (p = 0.0013). In addition, in the TNBC group, there was a significant association between the HDAC8 overexpression and tumor characteristics, including tumor size (p = 0.039), lymphatic invasion (p = 0.01), tumor grade (p = 0.02), and perineural invasion (p < 0.05). The cut-off value was fixed at 0.6279 r.u., and the corresponding sensitivity and specificity were found to be 73.91% and 70.37%, respectively. Conclusion: According to the findings, among the other markers, HDAC8 oncogene may be used as a potential tumor marker in the diagnosis of TNBC tumors.

miR-483-3p suppresses the proliferation and progression of human triple negative breast cancer cells by targeting the HDAC8>oncogene.

Triple negative breast cancer (TNBC) is a heterogeneous subclass of breast cancer (BC) distinguished by lack of hormone receptor expression. It is highly aggressive and difficult to treat with traditional chemotherapeutic regimens. Targeted-therapy using microRNAs (miR) has recently been proposed to improve the treatment of TNBC in the early stages. Here, we explore the roles of miR-483-3p/HDAC8 HDAC8 premiR-vector on tumorigenicity in TNBC patients. Clinical TNBC specimens and three BC cell lines were prepared. miR-483-3p and expression levels were measured using quantitative real-time polymerase chain reaction. Cell cycle progression was assessed by a flow-cytometry method. We also investigated cell proliferation by 3-2, 5-diphenyl tetrazolium bromide assay and colony formation assay. We used a to overexpress miR-483-3p, and a HDAC8-KO-vector for knocking out the endogenous production of HDAC8. Our data showed significant downregulation of miR-483-3p expression in TNBC clinical and cell line samples. The HDAC8 was also upregulated in both tissue specimens and BC cell lines. We found that increased levels of endogenous miR-483-3p affects tumorigenecity of MDA-MB-231. Downregulation of HDAC8 using the KO-vector showed the same pattern. Our results revealed that the miR-483-3p suppresses cellular proliferation and progression in TNBC cell lines via targeting HDAC8. Overall, our outcomes demonstrated the role of miR-483-3p as a tumor suppressor in TNBC and showed the possible mechanism via HDAC8. In addition, targeted treatment of TNBC with miR-483-3p might be considered in the future.

MiR-216b-5p inhibits cell proliferation in human breast cancer by down-regulating HDAC8 expression.

AIM: Over-expression of histone deacetylase 8 (HDAC8) has been demonstrated in breast cancer. But the underlying molecular mechanism of HDAC8 on the progression of breast cancer remains unknown. MicroRNAs (miRs) are proposed as important molecules in cancer progression by targeting specific oncogenes or tumor-suppressor genes. Our overall objective was to assess the miR-216b-5p role on HDAC8; and its impacts on breast cancer (BC) progression. MAIN METHODS: We acquired cancerous and noncancerous tissues from Iran Tumor Bank (I.T.B). The MDA-MB-231, MCF-7 and MCF-10A BC cell lines were also purchased. The tissue and cell line expression levels of miR-216b-5p and HDAC8 were determined by quantitative real-time PCR (qPCR). We next measured protein levels of HDAC8 by Western blotting assay. The cell cycle, cell proliferation, and colony formation assay were determined. Finally, we investigated the role of HDAC8 using a knockout vector; and confirmed the targeting of 3' untranslated region (3'-UTR) of HDAC8 through miR-216b-5p using a luciferase reporter assay. KEY FINDINGS: Our results demonstrated a significant decrease in miR-216b-5p, and remarkable increase in HDAC8 levels within human breast cancer tissues and cell lines. The lower levels of miR-216b-5p were negatively correlated with lymph node metastasis and advanced tumor size. The overexpression of miR-216b-5p in BC cell lines inhibited cellular proliferation and progression. HDAC8 was directly down-regulated by miR-216b-5p and knockout of HDAC8 showed the similar effects as miR-216b-5p overexpression. SIGNIFICANCE: Briefly, HDAC8 is an oncogene that accelerate breast cancer proliferation and progression and miR-216b-5p modulates those functions by binding to HDAC8 3'-UTR.