Downregulation of miroRNA-141 mediates acquired resistance to trastuzumab and is associated with poor outcome in breast cancer by upregulating the expression of ERBB4

miRNAs as biomarkers of therapeutic response to HER2-targeted treatment in breast cancer: A systematic review

Breast cancer is the most common type of lethal cancer in women globally. Women have a 1 in 8 chance of developing breast cancer in their lifetime. Among the four primary molecular subtypes (luminal A, luminal B, HER2+, and triple-negative), HER2+ accounts for 20-25 % of all breast cancer and is rather aggressive. Although the treatment outcome of HER2+ breast cancer patients has been significantly improved with anti-HER2 agents, primary and acquired drug resistance present substantial clinical issues, limiting the benefits of HER2-targeted treatment. MicroRNAs (miRNAs) play a central role in regulating acquired drug resistance. miRNA are single-stranded, non-coding RNAs of around 20-25 nucleotides, known for essential roles in regulating gene expression at the post-transcriptional level. Increasing evidence has demonstrated that miRNA-mediated alteration of gene expression is associated with tumorigenesis, metastasis, and tumor response to treatment. Comprehensive knowledge of miRNAs as potential markers of drug response can help provide valuable guidance for treatment prognosis and personalized medicine for breast cancer patients.

Deregulated miRNA Expression in Triple-Negative Breast Cancer of Ancestral Genomic-Characterized Latina Patients

Among patients with triple-negative breast cancer (TNBC), several studies have suggested that deregulated microRNA (miRNA) expression may be associated with a more aggressive phenotype. Although tumor molecular signatures may be race- and/or ethnicity-specific, there is limited information on the molecular profiles in women with TNBC of Hispanic and Latin American ancestry. We simultaneously profiled TNBC biopsies for the genome-wide copy number and miRNA global expression from 28 Latina women and identified a panel of 28 miRNAs associated with copy number alterations (CNAs). Four selected miRNAs (miR-141-3p, miR-150-5p, miR-182-5p, and miR-661) were validated in a subset of tumor and adjacent non-tumor tissue samples, with miR-182-5p being the most discriminatory among tissue groups (AUC value > 0.8). MiR-141-3p up-regulation was associated with increased cancer recurrence; miR-661 down-regulation with larger tumor size; and down-regulation of miR-150-5p with larger tumor size, high p53 expression, increased cancer recurrence, presence of distant metastasis, and deceased status. This study reinforces the importance of integration analysis of CNAs and miRNAs in TNBC, allowing for the identification of interactions among molecular mechanisms. Additionally, this study emphasizes the significance of considering the patients ancestral background when examining TNBC, as it can influence the relationship between intrinsic tumor molecular characteristics and clinical manifestations of the disease.

Circulating miR-141 as a potential biomarker for diagnosis, prognosis and therapeutic targets in gallbladder cancer

MicroRNA-141(miR-141) has been reported to play vital roles in the regulation of carcinogenesis and cancer progression. However, the biological function of miR-141 in GBC has received less attention. The aim of this study was to estimate the potential value of the expression level of miR-141 as a diagnostic and prognostic blood-based biomarker in gallbladder cancer (GBC) patients. Meanwhile, to explore its biological role in GBC cells. RT-PCR was employed to confirm the expression of miR-141 in ten paired tissue samples (10 GBC tissues and 10 adjacent normal gallbladder tissues), GBC cell lines and peripheral blood specimens from 98 GBC patients and 60 healthy controls. MTT assay was used to evaluate the GBC cells proliferation and flow cytometry was used to detect the cell apoptosis. Receiver operating characteristic curve analysis and the area under the curve (AUC) were used to evaluate the value of miR-141 plasma levels for GBC diagnosis. Finally, clinicopathological and survival data of all GBC patients were collected and analyzed. Here, we confirmed that the expression of miR-141 were upregulated in primary gallbladder cancer cells and tissues compared with human gallbladder epithelial cells and adjacent normal tissues (P < 0.0001). Meanwhile, we found that downregulated expression of miR-141 by miR-141 inhibitor could induce apoptosis and inhibit proliferation of GBC cells. Additionally, elevated plasma miR-141 expression was also detected in the peripheral blood of GBC patients compared with healthy controls (P < 0.0001). The AUC value of miR-141 for GBC diagnosis was 0.894 (95% CI 0.843–0.945), which was more valuable than those including carcinoembryonic antigen (CEA) (0.713, 95% CI 0.633–0.793), carbohydrate antigen 125 (CA125) (0.837, 95% CI 0.776–0.899) and carbohydrate antigen 19–9 (CA19-9) (0.869, 95% CI 0.813–0.924). The high expression level of miR-141 in plasma was significantly associated with tumor invasion (P = 0.008), lymph node metastasis (P < 0.0001) and advanced pathologic tumor/node/metastasis (pTNM) stage (P = 0.009). More importantly, high plasma miR-141 expression was an independent prognostic factor for predicting poorer long-term survival in GBC patients. Elevated expression of circulating miR-141 in peripheral blood might be a potential novel biomarker for diagnosis and prognosis of GBC patients. Downregulated expression of miR-141 could inhibit proliferation and induce apoptosis of GBC cells, that provide a potential therapeutic target for GBC.

Functional mechanism and clinical implications of miR-141 in human cancers

Cancer is caused by the abnormal proliferation of local tissue cells under the control of many oncogenic factors. MicroRNAs (miRNAs) are a class of evolutionarily conserved, approximately 22-nucleotide noncoding small RNAs that influence transcriptional regulationby binding to the 3'-untranslated region of target messenger RNA. As a member of the miRNA family, miR-141 acts as a suppressor or an oncomiR in various cancers and regulates cancer cell proliferation, apoptosis, invasion, and metastasis through a variety of signaling pathways, such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) and constitutive activation of nuclear factor-κB (NF-κB). Target gene validation and pathway analysis have provided mechanistic insight into the role of this miRNA in different tissues. This review also outlines novel findings that suggest miR-141 may be useful as a noninvasive biomarker and as a therapeutic target in several cancers.

Bone marrow mesenchymal stem cells-derived exosomal microRNA-16-5p restrains epithelial-mesenchymal transition in breast cancer cells via EPHA1/NF-κB signaling axis

OBJECTIVE

This study intends to conquer the mystery of microRNA-16-5p/erythropoietin-producing hepatocellular A1/nuclear factor-κB signaling (miR-16-5p/EPHA1/NF-κB signaling) in breast cancer.

METHODS

Expression of miR-16-5p, EPHA1 and NF-κB signaling-related proteins were detected. Gene overexpression or silencing was used to examine the biological roles of bone marrow mesenchymal stem cells (BMSCs)-derived exo-miR-16-5p in breast cancer. The effect of exo-miR-16-5p on tumorigenesis of breast cancer was confirmed by the xenograft nude mouse model.

RESULTS

Low miR-16-5p and high EPHA1 expression were examined in breast cancer. BMSCs-derived exosomes, up-regulated miR-16-5p or down-regulated EPHA1 restrained epithelial-mesenchymal transition (EMT) of breast cancer cells and tumor growth in nude mice. Down-regulated miR-16-5p or up-regulated EPHA1 activated NF-κB signaling. Knockdown of EPHA1 or inhibition of NF-κB signaling reversed the effects of down-regulated miR-16-5p on breast cancer cells.

CONCLUSION

BMSCs-derived exosomal miR-16-5p hinders breast cancer cells progression via EPHA1/NF-κB signaling axis.

The Role of MiRNA in Cancer: Pathogenesis, Diagnosis, and Treatment

Cancer is also determined by the alterations of oncogenes and tumor suppressor genes. These gene expressions can be regulated by microRNAs (miRNA). At this point, researchers focus on addressing two main questions: "How are oncogenes and/or tumor suppressor genes regulated by miRNAs?" and "Which other mechanisms in cancer cells are regulated by miRNAs?" In this work we focus on gathering the publications answering these questions. The expression of miRNAs is affected by amplification, deletion or mutation. These processes are controlled by oncogenes and tumor suppressor genes, which regulate different mechanisms of cancer initiation and progression including cell proliferation, cell growth, apoptosis, DNA repair, invasion, angiogenesis, metastasis, drug resistance, metabolic regulation, and immune response regulation in cancer cells. In addition, profiling of miRNA is an important step in developing a new therapeutic approach for cancer.

Is the regulation by miRNAs of NTPDase1 and ecto-5'-nucleotidase genes involved with the different profiles of breast cancer subtypes?

Breast cancer (BC) is a public health problem worldwide, causing suffering and premature death among women. As a heterogeneous disease, BC-specific diagnosis and treatment are challenging. Ectonucleotidases are related to tumor development and their expression may vary among BC. miRNAs may participate in epigenetic events and may regulate ectonucleotidases in BC. This study aimed to evaluate the expression of ectonucleotidases according to BC subtypes and to predict if there is post-transcriptional regulation of them by miRNAs. MCF 10A (non-tumorigenic), MCF7 (luminal BC), and MDA-MB-231 (triple-negative BC - TNBC) breast cell lines were used and ENTPD1 (the gene encoding for NTPDase1) and NT5E (the gene encoding for ecto-5'-nucleotidase) gene expression was determined. Interestingly, the expression of ENTPD1 was only observed in MCF7 and NT5E was lower in MCF7 compared to MDA-MB-231 cell line. ATP, ADP, and AMP hydrolysis were observed on the surface of all cell lines, being higher in MDA-MB-231. Like qPCR, the activity of AMP hydrolysis was also lower in the MCF7 cells, which may represent a striking feature of this BC subtype. In silico analyses confirmed that the miRNAs miR-101-3p, miR-141-3p, and miR-340-5p were higher expressed in MCF7 cells and targeted NT5E mRNA. Altogether, data suggest that the regulation of NT5E by miRNAs in MCF7 lineage may direct the molecular profile of luminal BC. Thus, we suggest that the roles of ecto-5'-nucleotidase and the aforementioned miRNAs must be unraveled in TNBC to be possibly defined as diagnostic and therapeutic targets.

Circulating and Intracellular miRNAs as Prognostic and Predictive Factors in HER2-Positive Early Breast Cancer Treated with Neoadjuvant Chemotherapy: A Review of the Literature

MicroRNAs (miRNA) are small noncoding RNAs that can act as both oncogene and tumor suppressors. Deregulated miRNA expression has been detected in human cancers, including breast cancer (BC). Considering their important roles in tumorigenesis, miRNAs have been investigated as potential prognostic and diagnostic biomarkers. Neoadjuvant setting is an optimal model to investigate in vivo the mechanism of treatment resistance. In the management of human epidermal growth factor receptor-2 (HER2)-positive early BC, the anti-HER2-targeted therapies have drastically changed the survival outcomes. Despite this, growing drug resistance due to the pressure of therapy is relatively frequent. In the present review, we focused on the main miRNAs involved in HER2-positive BC tumorigenesis and discussed the recent evidence on their predictive and prognostic value.

MicroRNAs as a clue to overcome breast cancer treatment resistance

Breast cancer is the most frequent cancer in women worldwide. Despite the improvement in diagnosis and treatments, the rates of cancer relapse and resistance to therapies remain higher than desirable. Alterations in microRNAs have been linked to changes in critical processes related to cancer development and progression. Their involvement in resistance or sensitivity to breast cancer treatments has been documented by different in vivo and in vitro experiments. The most significant microRNAs implicated in modulating resistance to breast cancer therapies are summarized in this review. Resistance to therapy has been linked to cellular processes such as cell cycle, apoptosis, epithelial-to-mesenchymal transition, stemness phenotype, or receptor signaling pathways, and the role of microRNAs in their regulation has already been described. The modulation of specific microRNAs may modify treatment response and improve survival rates and cancer patients' quality of life. As a result, a greater understanding of microRNAs, their targets, and the signaling pathways through which they act is needed. This information could be useful to design new therapeutic strategies, to reduce resistance to the available treatments, and to open the door to possible new clinical approaches.

Interference of long non-coding RNA HAGLROS inhibits the proliferation and promotes the apoptosis of ovarian cancer cells by targeting miR-26b-5p

Ovarian cancer (OV) is the fifth most common type of cancer affecting women worldwide. Long non-coding RNAs (lncRNAs) serve essential roles in the progression of OV. As such, the present study aimed to investigate the specific role of HAGLR opposite strand lncRNA (HAGLROS) in OV and the underlying mechanism of action through which HAGLROS exerts its effects on OV cells. In the present study, the expression of HAGLROS in several OV cell lines was first detected using reverse transcription-quantitative PCR. HAGLROS was then silenced to evaluate cell viability, proliferation and apoptosis, which were determined using Cell Counting Kit-8, colony formation and TUNEL assays, respectively. Additionally, immunofluorescence staining and western blotting were used to confirm the expression profile of proliferation- and apoptosis-related proteins. Moreover, a dual luciferase reporter assay was used to verify the potential interactions between HAGLROS and microRNA (miR)-26b-5p. Subsequently, rescue assays were performed to investigate the effects of HAGLROS and miR-26b-5p on OV progression. The results indicated that HAGLROS was highly expressed in OV cells. Interference of HAGLROS led to a decrease in the proliferation, but an increase in the apoptosis of OV cells, accompanied by downregulated expression levels of Ki67 and Bcl-2, and upregulated expression levels of Bax and cleaved caspase-3. Further study revealed that HAGLROS acted as a sponge for miR-26b-5p and positively regulated its expression. miR-26b-5p inhibitor transfection partially reversed the effects of HAGLROS knockdown on the proliferation and apoptosis of OV cells. In conclusion, the results of the present study suggested that interference of HAGLROS suppressed the proliferation and promoted the apoptosis of OV cells through regulating miR-26b-5p, indicating that HAGLROS may be a promising biomarker in OV diagnosis and treatment.

Association of ERBB4 genetic polymorphism with the risk and prognosis of non-small cell lung cancer in Chinese Han population: A population-based case-control study

The aim of this study was to explore the association of rs1836724 single-nucleotide polymorphism (SNP) of ERBB4 with risk and prognosis of non-small cell lung cancer (NSCLC) in the Chinese Han population.The genotype of rs1836724 SNP of ERBB4 from 258 patients with NSCLC and 200 noncancer controls were detected the TaqMan-MGB probes real-time fluorescence polymerase chain reaction. The distribution of genotype and alleles between the 2 groups was compared, and the association between clinicopathological characteristic and rs1836724 SNP was analyzed. Prognosis and influencing factors were analyzed by Kaplan-Meier and Cox regression analysis.There were significant differences in the genotype and allele distribution of ERBB4 rs1836724 between the NSCLC group and control group (P < .05). And CC genotype of rs1836724 was associated with increased risk of NSCLC in the Chinese Han population. Rs1836724 SNP was associated with TNM stage and lymph nodal metastasis (P = .001, P = .007). The median follow-up was 29 months, and the progression-free survival and overall survival of 258 NSCLC patients were 27.91% and 31.39%, respectively. Patients with GG genotype of rs1836724 had poor progression-free survival and overall survival. Rs1836724 SNP was an independent prognostic marker of NSCLC patients, CC genotype had a high risk of poor prognosis (odds ratio = 1.587, 95% confidence interval: 1.079-2.335, P = .019).In Chinese Han populations, rs1836724 SNP of ERBB4 may contribute toward the increased risk and poor prognosis of NSCLC.

Muscleblind-like 1 antisense RNA 1 inhibits cell proliferation, invasion, and migration of prostate cancer by sponging miR-181a-5p and regulating PTEN/PI3K/AKT/mTOR signaling

The present study aimed to investigate the role and underlying mechanisms of long non-coding RNA (lncRNA) muscleblind-like 1 antisense RNA 1 (MBNL1-AS1) in the progression of Prostate cancer (PCa). MBNL1-AS1 and microRNA (miR)-181a-5p expression in PCa tissues and several human PCa cell lines were analyzed, respectively, using StarBasev3.0 project and RT-qPCR assay. After MBNL1-AS1 overexpression, cell proliferation, invasion and migration were, respectively, evaluated using CCK-8, colony formation, transwell and wound healing assays. Dual luciferase assay were used for analysis of the interactions among MBNL1-AS1, miR-181a-5p, and phosphatase and tensin homolog (PTEN). Subsequently, the expression of PTEN and proteins in PI3K/AKT/mTOR signaling was examined using western blot analysis after transfection with miR-181a-5p mimic. The rescue assays were performed to investigate the effects of MBNL1-AS1 and miR-181a-5p on the functions of PCa cells and the expression of PTEN/PI3K/AKT/mTOR signaling by co-transfection with MBNL1-AS1 plasmid and miR-181a-5p mimic. Results indicated that MBNL1-AS1 was conspicuously downregulated while miR-181a-5p upregulating in PCa tissues and cell lines. MBNL1-AS1 overexpression decreased the abilities of cell proliferation, invasion, and migration. Further study revealed that MBNL1-AS1 acted as a sponge for miR-181a-5p and positively regulated PTEN by a sponge effect. Additionally, rescue assays proved that the effect of MBNL1-AS1-upregulation on the proliferation, invasion, and migration of PCa cells was dependent on miR-181a-5p. Furthermore, miR-181a-5p overexpression counteracted the expression of PTEN and proteins in PI3K/AKT/mTOR signaling exerted by MBNL1-AS1-upregulation in PCa cells. This study suggests that MBNL1-AS1 inhibits the progression of PCa via sponging miR-181a-5p and regulating PTEN/PI3K/AKT/mTOR pathway.

Nanoparticle-complexed antimiRs for inhibiting tumor growth and metastasis in prostate carcinoma and melanoma

Background

MiRNAs act as negative regulators of gene expression through target mRNA degradation or inhibition of its translation. In cancer, several miRNAs are upregulated and play crucial roles in tumorigenesis, making the inhibition of these oncomiRs an interesting therapeutic approach. This can be achieved by directly complementary single-stranded anti-miRNA oligonucleotides (antimiRs). A major bottleneck in antimiR therapy, however, is their efficient delivery. The nanoparticle formation with polyethylenimine (PEI) may be particularly promising, based on the PEI’s ability to electrostatically interact with oligonucleotides. This leads to their protection and supports delivery. In the present study, we explore for the first time PEI for antimiR formulation and delivery. We use the branched low molecular weight PEI F25-LMW for the complexation of different antimiRs, and analyse tumor- and metastasis-inhibitory effects of PEI/antimiR complexes in different tumor models.

Results

In prostate carcinoma, transfection of antimiRs against miR-375 and miR-141 leads to tumor cell inhibition in 2D- and 3D-models. More importantly, an in vivo tumor therapy study in prostate carcinoma xenografts reveals anti-tumor effects of the PEI/antimiR complexes. In advanced melanoma and metastasis, we identify by a microRNA screen miR-150 as a particularly relevant oncomiR candidate, and validate this result in vitro and in vivo. Again, the systemic application of PEI/antimiR complexes inhibiting this miRNA, or the previously described antimiR-638, leads to profound tumor growth inhibition. These effects are associated with the upregulation of direct miRNA target genes. In a melanoma metastasis mouse model, anti-metastatic effects of PEI/antimiR treatment are observed as well.

Conclusions

We thus describe PEI-based complexes as efficient platform for antimiR therapy, as determined in two different tumor entities using in vivo models of tumor growth or metastasis. Our study also highlights the therapeutic relevance of miR-375, miR-141, miR-150 and miR-638 as target miRNAs for antimiR-mediated inhibition.

Autophagy-mediating microRNAs in cancer chemoresistance

Chemoresistance is a complex phenomenon responsible for failure in response to chemotherapy agents and more than 90% of deaths in cancer patients. MicroRNAs (miRNAs), as a subgroup of non-coding RNAs with lengths between 21 and 25 nucleotides, are involved in various cancer processes like chemoresistance via interacting with their target mRNAs and suppressing their expression. Autophagy is a greatly conserved procedure involving the lysosomal degradation of cytoplasmic contents and organelles to deal with environmental stresses like hypoxia and starvation. Autophagy contributes to response to chemotherapy agents: autophagy can act as a protective mechanism for mediating the resistance in response to chemotherapy or can induce autophagic cell death and mediate the sensitivity to chemotherapy. On the other hand, one of the processes targeted by microRNAs in the regulation of chemoresistance is autophagy. Hence, we studied the literatures on chemoresistance mechanisms, the miRNAs' role in cancer, and the miRNAs' role in chemoresistance by modulating autophagy. Graphical Abstract.

circGNB1 Facilitates Triple-Negative Breast Cancer Progression by Regulating miR-141-5p-IGF1R Axis

As an intriguing class of RNA, circular RNAs (circRNAs) are vital mediators of various diseases including cancers. However, the biological role and underlying mechanism of the majority of circRNAs are still ambiguous in the progression of triple-negative breast cancer (TNBC). In this study, we characterized and further investigated hsa_circ_0009362 (circGNB1) by reanalyzing the circRNA microarray profiling in our previous study. Validating by qRT-PCR, circGNB1 was overexpressed in TNBC cell lines and high expression of circGNB1 was associated with worse clinical features and survival outcomes. The expression of circGNB1 was positively correlated with tumor size and clinical stage, and high expression of circGNB1 was an independent risk factor for TNBC patients. Cell proliferation, colony formation, wound-healing and mouse xenograft assays were carried out to investigate the functions of circGNB1. Both in vitro and in vivo assays revealed that knockdown of circGNB1 significantly suppressed cell proliferation, migration and tumor growth. Subsequently, we performed luciferase reporter assays and RNA immunoprecipitation assays to elucidate the underlying molecular mechanism of circGNB1. The results showed that circGNB1 sponges miR-141-5p and facilitates TNBC progression by upregulating IGF1R. Altogether, our study demonstrated the pivotal role of circGNB1-miR-141-5p-IGF1R axis in TNBC growth and metastasis though the mechanism of competing endogenous RNAs. Therefore, circGNB1 may have the potential to be a therapeutic target and novel prognostic biomarker for TNBC.

miR-519 regulates the proliferation of breast cancer cells via targeting human antigen R

Breast cancer is one of the most prevalent types of cancer among women that leads to millions of deaths worldwide every year. The mechanisms of breast cancer pathogenesis remain unclear. It has been reported that aberrant expression of miR-519, is associated with breast cancer development; however, the effects of miR-519 on breast cancer cell proliferation remain unknown. Therefore, the present study aimed to determine whether miR-519 could regulate breast cancer cell proliferation. A total of 20 pairs of primary breast cancer and adjacent normal tissues were collected from patients with breast cancer. miR-519 expression level was determined by reverse transcription-quantitative polymerase chain reaction. Furthermore, miR-519 mimics or inhibitors were transfected into breast cancer MCF-7 cells in order to up- or downregulate miR-519 expression. Subsequently, human antigen R (HUR), BCL-2 and BAX protein levels were analyzed by western blotting. MCF-7 cell proliferation was assessed using MTT and colony formation assays. A luciferase assay was performed to verify whether miR-519 could directly bind to HUR mRNA. The results demonstrated that miR-519 expression level was lower in primary breast cancer tissues compared with adjacent normal tissues. Furthermore, miR-519 overexpression and downregulation inhibited and stimulated MCF-7 cell proliferation, respectively. In addition, the results from luciferase assay demonstrated that HUR was a target of miR-519. HUR overexpression could reverse the effect of miR-519 mimics on MCF-7 cell proliferation, whereas HUR silencing could rescue the effect of miR-519 inhibitors on MCF-7 cell proliferation. These findings suggested that miR-519 may regulate MCF-7 cell proliferation by targeting HUR.

Modulation of the dual-faced effects of miR-141 with chitosan/miR-141 nanoplexes in breast cancer cells

BACKGROUND

miR-141, known as a tumor suppressive microRNA, is downregulated in breast cancer. However, recent contrasting studies report that it also acts as oncogene when it is upregulated. The present study aimed to investigate whether miR-141 is a tumor suppressor or oncogenic when it reaches normal levels in chitosan/miR-141 nanoplexes.

METHODS

Chitosan nanoplexes were prepared using simple complexation method. Nanoplexes were characterized by a gel retardation assay and zeta potential and particle size measurements. To determine the expression level of miR-141, a quantitative real-time polymerase chain reaction was performed. The effects of miR-141 mimics were investigated with respect to angiogenesis by vascular endothelial growth factor (VEGF), epithelial-mesenchymal transition (EMT) by E-cadherin, metastasis by Igfbp-4 and Tinagl1 enzyme-linked immunosorbent assays, invasion by an invasion chamber, and apoptosis by Annexin V.

RESULTS

The miR-141 expression levels of MDA-MB-231 and MDA-MB-435 cells by administration of chitosan/mimic miR-141 nanoplexes reached endogenous miR-141 levels of a non-tumorigenic epithelial breast cell line, MCF-10A. According to our results, metastasis, VEGF, EMT and invasion in breast cancer cells were diminished, whereas apoptosis increased by 1.5- and 2.4-fold in breast cancer cell lines as a result of the miR-141 mimics.

CONCLUSIONS

In conclusion, we have demonstrated that administration of miR-141 mimics at the determined doses to breast cancer cells revealed a tumor suppressor effect, and not the oncogenic face. The delivery of miR-141 by chitosan nanoplexes presents a promising approach for the suppression of breast cancer.

Gene Expression and miRNAs Profiling: Function and Regulation in Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Breast Cancer

Breast cancer is the second most common cause of cancer-related deaths among women worldwide. It is a heterogeneous disease with four major molecular subtypes. One of the subtypes, human epidermal growth factor receptor 2 (HER2)-enriched (HER2-positive) is characterized by the absence of estrogen and progesterone receptors and overexpression of HER2 receptor, and accounts for 15–20% of all breast cancers. Despite the anti-HER2 and cytotoxic chemotherapy, HER2 subtype is an aggressive disease with significant mortality. Recent advances in molecular biology techniques, including gene expression profiling, proteomics, and microRNA analysis, have been extensively used to explore the underlying mechanisms behind human breast carcinogenesis and metastasis including HER2-positive breast cancer, paving the way for developing new targeted therapies. This review focuses on recent advances on gene expression and miRNA status in HER2-positive breast cancer.