MicroRNA-21 Expression in Primary Breast Cancer Tissue Among Egyptian Female Patients and its Correlation with Chromosome 17 Aneusomy

Exploring research progress in studying serum exosomal miRNA-21 as a molecular diagnostic marker for breast cancer

Breast cancer is one of the most prevalent malignancies affecting women globally and poses a significant public health challenge. Early clinical detection plays a pivotal role in providing optimal treatment opportunities and favorable prognoses, crucial for reducing breast cancer mortality and enhancing patients' quality of life. Therefore, the timely identification and diagnosis of breast cancer are imperative. Conventional tumor markers, such as carcinoembryonic antigen (CEA) and carbohydrate antigen 15-3 (CA15-3), serve as reliable methods for actively monitoring disease progression and have become a routine auxiliary diagnostic approach in clinical settings. However, these biomarkers exhibit limitations in sensitivity and specificity, particularly in the early screening and diagnosis of tumors, often yielding results inconsistent with clinical manifestations. In recent years, research has increasingly focused on exosomes released by tumor cells as potential new biomarkers for early stage breast cancer screening. Exosomes carry various components, including tumor-derived proteins, nucleic acids, and lipids. This paper delves into the specific utilization of serum exosomal microRNA-21 (miR-21) as a biomarker for early detection and diagnosis of breast cancer, evaluating its efficacy within this framework.

MicroRNAs in breast cancer: New maestros defining the melody

MicroRNAs, short non-coding single-stranded RNAs, are important regulators and gatekeepers of the coding genes in the human genome. MicroRNAs are highly conserved among species and expressed in different tissues and cell types. They are involved in almost all the biological processes as apoptosis, proliferation, cell cycle arrest and differentiation. Playing all these roles, it is not surprising that the deregulation of the microRNA profile causes a number of diseases including cancer. Breast cancer, the most commonly diagnosed malignancy in women, accounts for the highest cancer-related deaths worldwide. Different microRNAs were shown to be up or down regulated in breast cancer. MicroRNAs can function as oncogenes or tumor suppressors according to their targets. In this review, the most common microRNAs implicated in breast cancer are fully illustrated with their targets. Besides, the review highlights the effect of exosomal microRNA on breast cancer and the effect of microRNAs on drug and therapies resistance as well as the miRNA-based therapeutic strategies used until today.

Genotoxic Effects in Human Fibroblasts Exposed to Microwave Radiation

In the last decades, technological development has led to an increasing use of devices and systems based on microwave radiation. The increased employment of these devices has elicited questions about the potential long-term health consequences associated with microwave radiation exposure. From this perspective, biological effects of microwave radiation have been the focus of many studies, but the reported scientific data are unclear and contradictory. The aim of this study is to evaluate the potential genotoxic and cellular effects associated with in vitro exposure of human fetal and adult fibroblasts to microwave radiation at the frequency of 25 GHz. For this purpose, several genetic and biological end points were evaluated. Results obtained from comet assay, phosphorylation of H2AX histone, and antikinetochore antibody (CREST)-negative micronuclei frequency excluded direct DNA damage to human fetal and adult fibroblasts exposed to microwaves. No induction of apoptosis or changes in prosurvival signalling proteins were detected. Moreover, CREST analysis showed for both the cell lines an increase in the total number of micronuclei and centromere positive micronuclei in exposed samples, indicating aneuploidy induction due to chromosome loss.

Interrelation of the Circulating and Tissue MicroRNA-21 with Tissue PDCD4 Expression and the Invasiveness of Iraqi Female Breast Tumors

The changes in the translational repression and variation in mRNA degradation induced by micro RNA are important aspects of tumorigenesis. The association of microRNA-21 with clinicopathologic features and expression of programed cell death 4 (PDCD4) in Iraqi female's with breast tumors has not been studied. MicroRNAs were extracted from a set of 60 breast tumor tissues and blood samples of females with breast cancer and benign breast lesions obtained after breast-reductive surgery, and only blood samples from 30 normal volunteers. These extracts were evaluated for miR-21 expression by quantitative RT-PCR. Analysis of PDCD4 protein expression was carried out as miR-21 target gene by immunohistochemical tests and correlating the results with patients' clinicopathological features. Significant overexpression of miRNA-21 was found in breast cancer group. The fold increase in the miR-21 gene expression was significantly higher in circulating exosomes and breast tissues of breast cancer patients as compared to other groups (P < 0.001). Overexpression of miR-21 was also significantly associated with the advanced tumor stage and histological grade. In breast cancer patients, PDCD4 protein expression was decreased to about 70% of the level in the control group. The delta Ct of exosomal and breast tissue miRNA-21 was negatively associated with PDCD4 expression. In conclusion, the translational repression of the PDCD4 induced by the high expression of miR-21 promotes breast cell transformation and development of breast tumor, and circulating miR-21 level could be applied to the screening panels for early detection of women breast cancer.

MiR-328 May be Considered as an Oncogene in Human Invasive Breast Carcinoma

Background

The recent investigations have rendered microRNAs (miRs) as a novel biomarker in cancer research. In fact, alteration in miR expression may be associated with tumor suppression, tumorigenesis, metastasis, and poor prognosis in human breast cancer (BC).

Objectives

The aim of this clinical experimental study was to measure the miR-328 expression level in breast cancer tissues, at first. Then, we tried to find out any possible correlation between miR-328 and prognostic and predictive biomarkers in BC. Both of these two objectives were investigated for the first time; and we did not find any similar survey measuring the expression level of miR-328 in both tumor and non-tumor breast tissues. This research was conducted in Iran (Ahvaz, Khuzestan), between December 2013 and April 2014. Furthermore, we did not find any previous document investigating the correlation between miR-328 expression level and prognostic factors in BC. Due to the lack of similar studies intending to measure the expression level of miR-328 in tumor and adjacent non-tumor tissues, we decided to carry out a pilot study.

Methods

We measured the expression level of miR-328 by Poly (A) real-time PCR based on SYBR Green-I in 28 fresh samples of BC tissues and 28 samples of normal adjacent tissues, including invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), and ductal carcinoma in situ (DCIS). We tried to attribute the results to clinicopathologic features such as status of estrogen and progesterone receptors (ER/PR), HER2/neu (HER2), P53 and also Ki67 labeling (Ki67-LI).

Results

The results showed that the miR-328 median level of expression was 0.88 (2^-ΔΔCt) (25^th-75^th percentile, 0.07 - 2.34). It means that the expression level increased in tumor tissues compared to normal adjacent tissues (NATs). However, a statistically significant correlation between the miR-328 median expression level and prognostic factors, including pathologic diagnosis, age, and also the status of ER, PR, HER2, and Ki67-LI was not observed (P > 0.05).

Conclusions

Therefore, it might be possible to consider miR-328 as an oncogene; but not necessarily an oncomiR, in human BC.

Prognostic value of circulating microRNA-21 for breast cancer: a systematic review and meta-analysis

BACKGROUND

There is an urgent need for novel noninvasive prognostic molecular tumor marker for monitoring the recurrence of breast cancer. MicroRNA-21 (miR-21) play a crucial role in the progression and aggressiveness of breast cancer, but its prognostic significance for patients with breast cancer remains inconclusive. The aim of this meta-analysis is to summarize the role of circulating miR-21 as a molecular marker in patients with breast cancer.

MATERIAL AND METHODS

Eligible studies were searched from the PubMed, EMBASE and Web of Science databases. The χ² and I² tests were used to evaluate heterogeneity between studies. The pooled hazard ratios (HR) with 95% confidence interval (CI) were calculated by a fixed-effects model, if no heterogeneity existed. If there was heterogeneity, a random-effects model was applied. The meta-analysis was conducted using the Review Manager 5 software.

RESULTS

A total of 7 articles which included 1629 cases were selected for the meta-analysis. Elevated miR-21 expression was significantly predictive of poor overall survival (HR = 1.51, 95%CI 1.15-1.98, p = 0.003). The subgroup analysis consisted of in tissue sample (HR = 1.66, 95%CI 1.03-2.67, p = 0.04) and serum sample (HR = 1.73, 95%CI 1.22-2.46, p = 0.002). The association between miR-21 expression level and lymph node metastasis was statistically significant (OR = 2.36, 95%CI 1.04-4.78, p = 0.03).

CONCLUSION

Our findings suggest that the circulating miR-21 expression level can predict poor prognosis in patients with breast cancer.

Exploration of the regulatory effect of miR-21 on breast cancer cell line proliferation and invasion as well as the downstream target genes

OBJECTIVE

To study the regulatory effects of miR-21 on breast cancer cell line proliferation and invasion as well as the downstream target genes.

METHODS

Breast cancer cell lines MCF-7 were cultured and transfected with miR-21 mimics and the corresponding negative control mimics (NC mimics), and then MTS kits were used to detect cell viability. Transwell experiment was used to detect cell invasion ability, and fluorescence quantitative PCR was used to detect the expression of proliferation and invasion-related genes in cells.

RESULTS

24 h after transfection of miR-21 mimics and NC mimics, cell OD value and the number of invasive cells of miR-21 group were significantly higher than those of NC group, and mRNA contents of PDCD-4, FasL, PTEN, RhoB, Maspin, TIMP3 and RECK in cells were significantly lower than those of NC group.

CONCLUSION

miR-21 can promote the proliferation and invasion of breast cancer cell lines, and its downstream target genes include PDCD-4, FasL, PTEN, RhoB, Maspin, TIMP3 and RECK.