miRNA - Therapeutic tool in breast cancer? Where are we now?

Tumor suppressive activity of miR-424-5p in breast cancer cells through targeting PD-L1 and modulating PTEN/PI3K/AKT/mTOR signaling pathway

AIMS

MicroRNAs (miRs) are key modulators of cellular processes such as proliferation, apoptosis, as well as anti-cancer immune responses. Here, we evaluated the role of miR-424-5p in breast cancer (BC) and investigated its effects on T cell-related immune response.

MAIN METHODS

BC tissues and cell lines were prepared and the expression of miR-424-5p and PD-L1, as well as the underlying molecular pathways, were assessed via qRT-PCR and western blotting. The MTT assay and flow cytometry were used to assess the effect of miR-424-5p on proliferation, apoptosis, autophagy, and cell cycle progression. The co-culture of T cells with MDA-MB-231 was performed for evaluating the role of miR-424-5p in rescuing T cell exhaustion.

KEY FINDINGS

The results indicated the down-regulation of miR-424-5p and up-regulation of PD-L1 expression in BC tissue specimens. MiR-424-5p transfection into PD-L1 overexpressing MDA-MB-231 cells decreased the expression of PD-L1. Also, miR-424-5p could reduce MDA-MB-231 cell viability through modulating apoptosis and autophagy pathways. Furthermore, miR-424-5p transfection leads to decreased colony formation and increased cell number at the G2/M phase. Western blot analysis illustrated that miR-424-5p could exert its anti-proliferative effect via modulating PTEN/PI3K/AKT/mTOR pathway. Moreover, it was demonstrated that suppression of PD-L1 by miR-424-5p could participate in regulating the expression of effector cytokines in T cells.

SIGNIFICANCE

MiR-424-5p could be considered as a potential tumor-suppressor miR in regulating BC cellular growth, apoptosis, and T cell-related immune response through targeting PD-L1, and its downstream mediators. Therefore, we recognized miR-424-5p as a promising candidate for miR restoration therapy in BC patients.

lncRNA H19 promotes viability and epithelial-mesenchymal transition of lung adenocarcinoma cells by targeting miR-29b-3p and modifying STAT3

Considering the joint contribution of long non‑coding RNAs (lncRNAs) and microRNAs (miRNAs/miRs) to tumorigenesis, the aim of the present study was to investigate whether and how lncRNA H19 targets miR‑29b‑3p to affect the progression of lung adenocarcinoma by the modulation of signal transducer and activator of transcription 3 (STAT3). A total of 305 lung adenocarcinoma tissues and four human lung adenocarcinoma cell lines (i.e. Calu‑3, NCI‑H1975, A549 and NCI‑H23) were used. pcDNA3.1‑H19, short interfering RNA (si‑)H19, miR‑29b‑3p mimic, miR‑29b‑3p inhibitor and negative control (NC) were transfected into the cells, and the proliferation, viability and apoptosis of the cells were determined using a Cell Counting Kit‑8 assay, colony formation assay and flow cytometry, respectively. The results indicated that highly expressed H19 and poorly expressed miR‑29b‑3p could serve as predictors for the poor prognosis of lung adenocarcinoma patients. Additionally, si‑H19 and miR‑29b‑3p mimic significantly increased the apoptosis of lung adenocarcinoma cells, and decreased the survival rate and viability of cells. Simultaneously, expression of epithelial‑mesenchymal transition (EMT)‑specific proteins was significantly altered, i.e. increased epithelial cadherin expression, as well as decreased vimentin, Snail and Slug expression. Furthermore, miR‑29b‑3p was verified to be targeted and regulated by H19, and STAT3 was targeted and modified by miR‑29b‑3p. Ultimately, STAT3 was identified to decrease lung adenocarcinoma cell viability, survival, apoptosis and EMT imposed by miR‑29b‑3p. In conclusion, the results of the present study indicated that lncRNA H19/miR‑29b‑3p/STAT3 signaling was involved in the development of lung adenocarcinoma, which may be critical for developing effective diagnostic and treatment strategies for lung adenocarcinoma.

MicroRNA-493 is a prognostic factor in triple-negative breast cancer

Breast cancer is one of the most common malignant diseases in women. Triple‐negative breast cancer (TNBC) shows higher aggressiveness and recurrence rates than other subtypes, and there are no effective targets or tailored treatments for TNBC patients. Thus, finding effective prognostic markers for TNBC could help clinicians in their ability to care for their patients. We used tissue microarrays (TMAs) to detect microRNA‐493 (miR‐493) expression in breast cancer samples. A miRCURY LNA detection probe specific for miR‐493 was used in in situ hybridization assays. Staining results were reviewed by two independent pathologists and classified as high or low expression of miR‐493. Kaplan–Meier survival plots and multivariate Cox analysis were carried out to clarify the relationship between miR‐493 and survival. In the Kaplan–Meier analysis, patients with high miR‐493 expression had better disease‐free survival than patients with low miR‐493 expression. After adjusting for common clinicopathological factors in breast cancer, the expression level of miR‐493 was still a significant prognostic factor in breast cancer. Further subtype analysis revealed that miR‐493 expression levels were only significantly prognostic in TNBC patients. These results were validated in the Molecular Taxonomy of Breast Cancer International Consortium database for overall survival. We proved the prognostic role of miR‐493 in TNBC by using one of the largest breast cancer TMAs available and validated it in a large public RNA sequencing database.

Promotional effect of microRNA-194 on breast cancer cells via targeting F-box/WD repeat-containing protein 7

Breast cancer is the most common type of malignant cancer in females. An increasing number of studies have revealed that microRNAs (miR), which belong to a class of small non-coding RNAs, serve an important role in a number of human cancer subtypes. In the present study, the role of miR-194 in breast cancer cells and its underlying mechanisms were investigated. The results demonstrated that the serum levels of miR-194 were significantly higher in patients of the poorly differentiated and well-differentiated groups, compared with in healthy adults. Additionally, the serum level of miR-194 was significantly higher in the poorly differentiated group compared with in the well-differentiated group. In order to further investigate the role of miR-194 in breast cancer cells, the present study transfected two breast cancer cell lines, MCF-7 and MDA-MB-231, with an empty vector (control), miR-194 (overexpression), antagomiR-194 (inhibitor, functional knock down) or antagomiR-194 and miR-194. An MTT assay was performed in order to detect the proliferation of breast cancer cells in the various groups. The results revealed that the overexpression of miR-194 significantly accelerated cell proliferation, whereas the inhibition of miR-194 significantly decelerated the proliferation of MCF-7 and MDA-MB-231 cells. Furthermore, the expression levels of cyclin D and cyclin E were significantly upregulated in miR-194 overexpressing cells, and the expression levels of cyclin D and cyclin E were significantly downregulated in miR-194 inhibited cells, as compared with in control cells. No significant change was observed in the level of proliferation of cells co-transfected with miR-194 and antagomiR-194, compared with in the control cells. According to the hypothesis suggesting possible target genes of miR-194, the present study proposed that F-box/WD repeat-containing protein 7 (Fbxw-7) may be a direct target of miR-194, which was confirmed by a luciferase reporter assay. The present study suggested that miR-194 expression promoted the proliferation of breast cancer cells by targeting Fbxw-7, and may serve as a biomarker and a novel target for breast cancer therapy.

Identification of novel microRNAs regulating HLA-G expression and investigating their clinical relevance in renal cell carcinoma

The non-classical human leukocyte antigen G (HLA-G) is expressed at a high frequency in renal cell carcinoma (RCC) and is associated with a higher tumor grade and a poor clinical outcome. This might be caused by the HLA-G-mediated inhibition of the cytotoxicity of T and NK cells. Therefore a selective targeting of HLA-G might represent a powerful strategy to enhance the immunogenicity of RCC lesions. Recent studies identified a number of HLA-G-regulating microRNAs (miRs) and demonstrated an inverse expression of some of these miRs with HLA-G in RCC in vitro and in vivo. However, it was postulated that further miRs might exist contributing to the tightly controlled selective HLA-G expression.By application of a miR enrichment assay (miTRAP) in combination with in silico profiling two novel HLA-G-regulatory miRs, miR-548q and miR-628-5p, were identified. Direct interactions of both miRs with the 3' untranslated region of HLA-G were confirmed with luciferase reporter gene assays. In addition, qPCR analyses and immunohistochemical staining revealed an inverse, expression of miR-628-5p, but not of miR-548q to the HLA-G protein in primary RCC lesions and cell lines. Stable overexpression of miR-548q and miR-628-5p caused a downregulation of HLA-G mRNA and protein. This leads in case of miR-548q to an enhanced NK cell-mediated HLA-G-dependent cytotoxicity, which could be reverted by ILT2 blockade suggesting a control of the immune effector cell activity at least by this miR. The identification of two novel HLA-G-regulatory miRs extends the number of HLA-G-relevant miRs tuning the HLA-G expression and might serve as future therapeutic targets.

miR-10b, miR-26a, miR-146a And miR-153 Expression in Triple Negative Vs Non Triple Negative Breast Cancer: Potential Biomarkers

MicroRNAs (miRNAs) are small non-coding RNAs composed of 18-25 nucleotides that can post-transcriptionally regulate gene expression and have key regulatory roles in cancer, acting as both oncogenes and tumor suppressors. About 1000 genes in humans encode miRNAs, which account for approximately 3% of the human genome, and up to 30% of human protein coding genes may be regulated by miRNAs. The objective of this article is to evaluate the expression profile of four miRNAs previously implicated in triple negative breast cancer: miR-10b, miR-26a, miR-146a and miR-153, and to determine their possible interaction in triple negative and non triple negative breast cancer based on clinical outcome and the expression of BRCA1. 24 triple-negative and 13 non triple negative breast cancer cases, were studied by q-RT-PCR and immunohistochemistry to determine the expression of the four studied miRNAs and the BRCA1 protein, respectively. We observed that the BRCA1 protein was absent in 62.5% of the triple negative cases. Besides, the miR-146a and miR-26a were over expressed in triple negative breast cancer. These two miRNAs, miR-10b and miR-153 were significantly associated to lymph node metastases occurrence in triple negative breast carcinoma. All the analyzed microRNAs were not associated with the expression of BRCA1 in our conditions. Our work provides evidence that miR-146a, miR-26a, miR-10b and miR-153 could be defined as biomarkers in triple negative breast cancer to predict lymph node metastases (LNM).

Pseudogene PTENP1 Functions as a Competing Endogenous RNA (ceRNA) to Regulate PTEN Expression by Sponging miR-499-5p

Increasing evidence has shown that pseudogenes can widely regulate gene expression. However, little is known about the specific role of PTENP1 and miR-499-5p in insulin resistance. The relative transcription level of PTENP1 was examined in db/db mice and high fat diet (HFD)-fed mice by real-time PCR. To explore the effect of PTENP1 on insulin resistance, adenovirus overexpressing or inhibiting vectors were injected through the tail vein. Bioinformatics predictions and a luciferase reporter assay were used to explore the interaction between PTENP1 and miR-499-5p. The relative transcription level of PTENP1 was largely enhanced in db/db mice and HFD-fed mice. Furthermore, the overexpression of PTENP1 resulted in impaired Akt/GSK activation as well as glycogen synthesis, while PTENP1 inhibition led to the improved activation of Akt/GSK and enhanced glycogen contents. More importantly, PTENP1 could directly bind miR-499-5p, thereby becoming a sink for miR-499-5p. PTENP1 overexpression results in the impairment of the insulin-signaling pathway and may function as a competing endogenous RNA for miR-499-5p, thereby contributing to insulin resistance.

Pre and post radiotherapy serum oxidant/antioxidant status in breast cancer patients: Impact of age, BMI and clinical stage of the disease

AIM

In this study the effects of radiation therapy (RT) on serum oxidant/antioxidant status in breast cancer patients and the impact of age, BMI and clinical stage of the disease on the aforementioned variables were investigated.

BACKGROUND

RT that is used for cancer treatment is dependent on the production of reactive oxygen species.

MATERIALS AND METHODS

Eighty patients with breast cancer participated in this study and received RT at a dose of 50 Gy for 5 weeks. Blood samples were obtained in one day before and after the end of RT. Serum status of malondialdehyde (MDA), total antioxidant status (TAS), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were analyzed by spectrophotometry or ELISA and selenium (Se) level were analyzed by atomic absorption spectrometry. Paired t-test was used for comparing pre and post radiotherapy data.

RESULTS

Before and after the radiotherapy, a significant increase in MDA level was observed, while a significant decrease in GPx activity, SOD, TAS and Se levels were found (p < 0.05). The level of the CAT enzyme had no significant changes (p = 0.568). The results showed some changes in the status of TAS, SOD and GPx which are associated with age, BMI and clinical stage of the disease.

CONCLUSION

It seems that RT would have the potential to cause variations in the status of antioxidant/oxidant system. Although, some changes in variables were observed by sub-classification of the age, BMI and the disease stage, but it seems that these changes are not necessarily dependent to them.

Pokemon siRNA Delivery Mediated by RGD-Modified HBV Core Protein Suppressed the Growth of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a deadly human malignant tumor that is among the most common cancers in the world, especially in Asia. Hepatitis B virus (HBV) infection has been well established as a high risk factor for hepatic malignance. Studies have shown that Pokemon is a master oncogene for HCC growth, suggesting it as an ideal therapeutic target. However, efficient delivery system is still lacking for Pokemon targeting treatment. In this study, we used core proteins of HBV, which is modified with RGD peptides, to construct a biomimetic vector for the delivery of Pokemon siRNAs (namely, RGD-HBc-Pokemon siRNA). Quantitative PCR and Western blot assays revealed that RGD-HBc-Pokemon siRNA possessed the highest efficiency of Pokemon suppression in HCC cells. In vitro experiments further indicated that RGD-HBc-Pokemon-siRNA exerted a higher tumor suppressor activity on HCC cell lines, evidenced by reduced proliferation and attenuated invasiveness, than Pokemon-siRNA or RGD-HBc alone. Finally, animal studies demonstrated that RGD-HBc-Pokemon siRNA suppressed the growth of HCC xenografts in mice by a greater extent than Pokemon-siRNA or RGD-HBc alone. Based on the above results, Pokemon siRNA delivery mediated by RGD-modified HBV core protein was shown to be an effective strategy of HCC gene therapy.