MicroRNA-21 links epithelial-to-mesenchymal transition and inflammatory signals to confer resistance to neoadjuvant trastuzumab and chemotherapy in HER2-positive breast cancer patients

The Impact of Pdcd4, a Translation Inhibitor, on Drug Resistance

Programmed cell death 4 (Pdcd4) is a tumor suppressor, which has been demonstrated to efficiently suppress tumorigenesis. Biochemically, Pdcd4 binds with translation initiation factor 4A and represses protein translation. Beyond its role in tumor suppression, growing evidence suggests that Pdcd4 enhances the chemosensitivity of several anticancer drugs. To date, numerous translational targets of Pdcd4 have been identified. These targets govern important signal transduction pathways, and their attenuation may improve chemosensitivity or overcome drug resistance. This review will discuss the signal transduction pathways regulated by Pdcd4 and the potential mechanisms through which Pdcd4 enhances chemosensitivity or counteracts drug resistance.

Extracellular vesicle-mediated drug delivery in breast cancer theranostics

Breast cancer (BC) continues to be a significant global challenge due to drug resistance and severe side effects. The increasing prevalence is alarming, requiring new therapeutic approaches to address these challenges. At this point, Extracellular vesicles (EVs), specifically small endosome-released nanometer-sized EVs (SEVs) or exosomes, have been explored by literature as potential theranostics. Therefore, this review aims to highlight the therapeutic potential of exosomes in BC, focusing on their advantages in drug delivery and their ability to mitigate metastasis. Following the review, we identified exosomes' potential in combination therapies, serving as miRNA carriers and contributing to improved anti-tumor effects. This is evident in clinical trials investigating exosomes in BC, which have shown their ability to boost chemotherapy efficacy by delivering drugs like paclitaxel (PTX) and doxorubicin (DOX). However, the translation of EVs into BC therapy is hindered by various challenges. These challenges include the heterogeneity of EVs, the selection of the appropriate parent cell, the loading procedures, and determining the optimal administration routes. Despite the promising therapeutic potential of EVs, these obstacles must be addressed to realize their benefits in BC treatment.

Circulating miRNA-21 Levels in Breast Cancer Patients Before and After Chemotherapy and Its Association with Clinical Improvement

Breast cancer is the most frequent type of cancer in women, many patients experience recurrences and metastasis. miR-21 (microRNA-21) as biomarker is under investigation for breast cancer. At present, there is very limited information available regarding effect of chemotherapy on miR-21 expression in breast cancer and its correlation with the clinical improvement. Hence, this study was planned to evaluate the effect of chemotherapy on miR-21 in metastatic breast cancer and its relationship with the clinical outcome. Females, aged-18-90 years diagnosed with Invasive Ductal Carcinoma of breast and candidate of neoadjuvant chemotherapy including Adriamycin (60 mg/m2), Cyclophosphamide (600 mg/m2) with or without Taxane (75-175 mg/m2) were included in the study. Before and after 42 days of staring of chemotherapy sample was collected for circulatory miR-21 and RECIST 1.1 criteria was applied to assess the clinical status. Blood samples for routine clinical biomarkers including liver function test and renal function tests was also collected. miR-21 expression before and after chemotherapy was assessed using standard method based on real time PCR. Expression of miR-21, RECIST criteria and other liver and kidney related biomarkers were compared before and after chemotherapy. After neoadjuvant chemotherapy expression of miR-21 was significantly increased by 5.65-fold. There was significant improvement in clinical scores based on RECIST criteria (0.046). No significant correlation was observed between miR-21 expression and difference in RECIST score (r = - 0.122, p = 0.570). Neoadjuvant chemotherapy causes clinical improvement in breast cancer patients however it is not correlated with the miR-21 expression which significantly increased after chemotherapy.

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.

Drug resistance mechanisms in cancers: Execution of pro-survival strategies

One of the quintessential challenges in cancer treatment is drug resistance. Several mechanisms of drug resistance have been described to date, and new modes of drug resistance continue to be discovered. The phenomenon of cancer drug resistance is now widespread, with approximately 90% of cancer-related deaths associated with drug resistance. Despite significant advances in the drug discovery process, the emergence of innate and acquired mechanisms of drug resistance has impeded the progress in cancer therapy. Therefore, understanding the mechanisms of drug resistance and the various pathways involved is integral to treatment modalities. In the present review, I discuss the different mechanisms of drug resistance in cancer cells, including DNA damage repair, epithelial to mesenchymal transition, inhibition of cell death, alteration of drug targets, inactivation of drugs, deregulation of cellular energetics, immune evasion, tumor-promoting inflammation, genome instability, and other contributing epigenetic factors. Furthermore, I highlight available treatment options and conclude with future directions.

Non-coding RNAs mediated inflammation in breast cancers

Breast cancer is the major cancer that affects women all over the world. The awareness over past several decades has led to intensive screening and detection as well as successful treatments. Still, the breast cancer mortality is unacceptable and needs to be urgently addressed. Among many factors, inflammation has often been associated with tumorigenesis, including breast cancer. More than a third of all breast cancer deaths are marked by deregulated inflammation. The exact mechanisms are still not completely known but among the many putative factors, the epigenetic changes, particularly those mediated by non-coding RNAs are fascinating. microRNAs, long non-coding RNAs as well as circular RNAs seem to impact the inflammation in breast cancer which further highlights their important regulatory role in breast cancer pathogenesis. Understanding inflammation in breast cancer and its regulation by non-coding RNAs is the primary objective of this review article. We attempt to provide the most complete information on the topic in hopes of opening new areas of research and discoveries.

Inflammatory cytokines and two subtypes of breast cancer: A two-sample mendelian randomization study

BACKGROUND

Breast cancer is a common cancer type that leads to cancer-related deaths among women. HER2-positive breast cancer, in particular, is associated with poor prognosis due to its high aggressiveness, increased risk of recurrence, and metastasis potential. Previous observational studies have explored potential associations between inflammatory cytokines and the risk of two breast cancer subtypes (HER2-positive and HER2-negative), but the results have been inconsistent. To further elucidate the causal relationship between inflammatory cytokines and the two breast cancer subtypes, we conducted a two-sample Mendelian randomization (MR) study.

METHODS

We employed a two-sample bidirectional MR analysis using publicly available genome-wide association study (GWAS) statistics. After obtaining instrumental variables, we conducted MR analyses using five different methods to ensure the reliability of our results. Additionally, we performed tests for heterogeneity and horizontal pleiotropy. Subsequently, we conducted a reverse MR study by reversing exposure and outcome variables.

RESULTS

Evidence from our IVW analysis revealed that genetically predicted levels of IL-5 [odds ratio (OR): 1.18, 95% confidence interval (CI): 1.04-1.35, P = 0.012], IL-7 (OR: 1.11, 95% CI: 1.01-1.22, P = 0.037), and IL-16 (OR: 1.13, 95% CI: 1.02-1.25, P = 0.025) were associated with an increased risk of HER2-positive breast cancer. Conversely, IL-10 (OR: 1.14, 95% CI: 1.03-1.26, P = 0.012) was associated with an increased risk of HER2-negative breast cancer. These results showed no evidence of heterogeneity or horizontal pleiotropy (P > 0.05). Results from the reverse MR analysis indicated no potential causal association between breast cancer and inflammatory cytokines (P > 0.05).

CONCLUSION

Our findings demonstrate that IL-5, IL-7, and IL-16 are risk factors for HER2-positive breast cancer, with varying degrees of increased probability of HER2-positive breast cancer associated with elevated levels of these inflammatory cytokines. Conversely, IL-10 is a risk factor for HER2-negative breast cancer. Reverse studies have confirmed that breast cancer is not a risk factor for elevated levels of inflammatory cytokines. This series of results clarifies the causal relationship between different types of inflammatory cytokines and different subtypes of breast cancer. Based on this research, potential directions for the mechanism research of different inflammatory cytokines and different subtypes of breast cancer have been provided, and potential genetic basis for identifying and treating different subtypes of breast cancer have been suggested.

Plasma microRNA-195, -34c, and - 1246 as novel biomarkers for the diagnosis of trastuzumab-resistant HER2-positive breast cancer patients

Recently, miRNAs have been regarded as potential candidates for mediating therapeutic functions by targeting genes related to drug response. In this study, we suggested that plasma miRNAs may be correlated with response to trastuzumab in HER2-positive breast cancer patients. To determine whether miR-195, miR-23b-3p, miR-1246, and miR-34c-3p are involved in trastuzumab resistance, we screened their expressions in the BT-474 cell line, which was followed by plasma analysis from 20 trastuzumab-resistant HER2-positive breast cancer patients and 20 nonresistance subjects. Then, TargetScan, Pictar, and miRDB were applied to find the possible targets of the selected miRNAs. In addition, the expression status of admitted targets was evaluated. Our results showed that in resistant BT-474 cells, miR-1246, and miR-23b-3p were significantly upregulated, and miR-195-5p and miR-34c-3p were downregulated. In plasma analysis, we found miR-195-5p, miR-34c-3p, and miR-1246 meaningfully diminished in the resistant group, while the expression of miR-23b-3p was not statistically different. The expression levels of confirmed targets by qRT-PCR showed that the expression of RAF1, AKT3, c-MET, CCND1, PHLPP2, MYB, MAP2K1, and PTEN was significantly upregulated, while the expression of CCNG2 was significantly downregulated. The networks of miRNAs with their confirmed targets improved comprehension of miRNA-mediated therapeutic responses to trastuzumab and might be proposed for more characterization of miRNA functions. Moreover, these data indicated that miR-195-5p, miR-34c-3p, and miR-1246 could be possible biomarkers for prognosis and early detection of the trastuzumab-resistant group from the sensitive group of HER2-positive breast cancer patients.

The impact of microRNAs on the resistance of breast cancer subtypes to chemotherapy

Breast cancer (BC) formation is primarily influenced by genetics, epigenetics and environmental factors. Aberrant Genetics and epigenetics leads to a condition known as heterogeneity. The heterogeneity of BC can be divided into several subtypes. Among the epigenetic factors, microRNAs (miRNAs) have been shown to play a crucial role in the development and progression of malignancies. These small non-coding RNAs regulate gene expression through a variety of mechanisms, resulting in either mRNA degradation or translation repression. As miRNAs directly control many proteins, genetic anomalies affect tumor metastasis, apoptosis, proliferation, and cell transportation. Consequently, miRNA dysregulations contribute not only in cancer development but also in invasiveness, proliferation rate and more importantly, drug response. Findings mostly indicate subtype-specified identical miRNA profile in BC. Among the BC subtypes, TNBC, HER2 + and luminal are the most resistant to therapy, respectively. Therapy resistance is greatly associated with miRNA expression profile. Hence, concentration of miRNA is the first marker of its role in chemotherapy response. Overexpressed miRNAs may disrupt drug efflux transporters and decrease the drug accumulation in cell. While down-regulated miRNAs which mediate drug resistance processes are mostly correlated with poor treatment response. Moreover, other mechanisms in which miRNAs play crucial roles in chemoresistance such as cell receptor mediations, dysregulation by environmental factors, DNA defects, etc. Recently, several miRNA-based treatments have shown promising results in cancer treatment. Inhibition of up-regulated miRNAs is one of these therapeutic approaches whilst transfecting cell with down-regulated miRNAs also show promising results. Moreover, drug-resistance could also be determined while in the pre-treatment phase via expression levels of miRNAs. Therefore, miRNAs provide intriguing insights and challenges in overcoming chemoresistance. In this article, we have discussed how miRNAs regulate breast cancer subtypes-specific chemoresistance.

Unlocking the Potential of Circulating miRNAs in the Breast Cancer Neoadjuvant Setting: A Systematic Review and Meta-Analysis

The potential role of circulating microRNAs (miRNAs) as biomarkers in breast cancer (BC) management has been widely reported. However, the numerous discrepancies between studies in this regard hinders the implementation of circulating miRNAs in routine clinical practice. In the context of BC patients undergoing neoadjuvant chemotherapy (NAC), the possibility of predicting NAC response may lead to prognostic improvements by individualizing post-neoadjuvant therapy. In this context, the present meta-analysis aims to clarify circulating miRNAs' predictive role with respect to NAC response among BC patients. We conducted a comprehensive literature search on five medical databases until 16 February 2023. We pooled the effect sizes of each study by applying a random-effects model. Cochran's Q test (p-level of significance set at 0.05) scores and I² values were assessed to determine between-study heterogeneity. The PROBAST (Prediction Model Risk of Bias Assessment Tool) tool was used to evaluate the selected studies' risk of bias. Overall, our findings support the hypothesis that circulating miRNAs, specifically miR-21-5p and miR-155-5p, may act as predictive biomarkers in the neoadjuvant setting among BC patients. However, due to the limited number of studies included in this meta-analysis and the high degrees of clinical and statistical heterogeneity, further research is required to confirm the predictive power of circulating miR-21-5p and miR-155-5p.

New Biomarkers and Treatment Advances in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a specific subtype of breast cancer lacking hormone receptor expression and HER2 gene amplification. TNBC represents a heterogeneous subtype of breast cancer, characterized by poor prognosis, high invasiveness, high metastatic potential, and a tendency to relapse. In this review, the specific molecular subtypes and pathological aspects of triple-negative breast cancer are illustrated, with particular attention to the biomarker characteristics of TNBC, namely: regulators of cell proliferation and migration and angiogenesis, apoptosis-regulating proteins, regulators of DNA damage response, immune checkpoints, and epigenetic modifications. This paper also focuses on omics approaches to exploring TNBC, such as genomics to identify cancer-specific mutations, epigenomics to identify altered epigenetic landscapes in cancer cells, and transcriptomics to explore differential mRNA and protein expression. Moreover, updated neoadjuvant treatments for TNBC are also mentioned, underlining the role of immunotherapy and novel and targeted agents in the treatment of TNBC.

Endothelial plasticity across PTEN and Hippo pathways: A complex hormetic rheostat modulated by extracellular vesicles

Vascularization is a multifactorial and spatiotemporally regulated process, essential for cell and tissue survival. Vascular alterations have repercussions on the development and progression of diseases such as cancer, cardiovascular diseases, and diabetes, which are the leading causes of death worldwide. Additionally, vascularization continues to be a challenge for tissue engineering and regenerative medicine. Hence, vascularization is the center of interest for physiology, pathophysiology, and therapeutic processes. Within vascularization, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and Hippo signaling have pivotal roles in the development and homeostasis of the vascular system. Their suppression is related to several pathologies, including developmental defects and cancer. Non-coding RNAs (ncRNAs) are among the regulators of PTEN and/or Hippo pathways during development and disease. The purpose of this paper is to review and discuss the mechanisms by which exosome-derived ncRNAs modulate endothelial cell plasticity during physiological and pathological angiogenesis, through the regulation of PTEN and Hippo pathways, aiming to establish new perspectives on cellular communication during tumoral and regenerative vascularization.

Targeted Therapy and Mechanisms of Drug Resistance in Breast Cancer

Breast cancer is the most common cause of cancer-related death in women worldwide. Multidrug resistance (MDR) has been a large hurdle in reducing BC death rates. The drug resistance mechanisms include increased drug efflux, enhanced DNA repair, senescence escape, epigenetic alterations, tumor heterogeneity, tumor microenvironment (TME), and the epithelial-to-mesenchymal transition (EMT), which make it challenging to overcome. This review aims to explain the mechanisms of resistance in BC further, identify viable drug targets, and elucidate how those targets relate to the progression of BC and drug resistance.

Circular Sponge against miR-21 Enhances the Antitumor Activity of Doxorubicin against Breast Cancer Cells

Breast cancer is the most common type of cancer in women, with chemotherapy being the main strategy. However, its effectiveness is reduced by drug resistance mechanisms. miR-21 is upregulated in breast cancer that has been linked to drug resistance and carcinogenic processes. Our aim was to capture miR-21 with a circular sponge (Circ-21) and thus inhibit the carcinogenic processes and drug resistance mechanisms in which it participates. Proliferation, migration, colony formation, cell cycle, and poly [ADP-ribose] polymerase 1 (PARP-1) and vascular endothelial growth factor (VEGF) detection assays were performed with MCF7 breast cancer cells and MCF10A non-tumor cells. In addition, doxorubicin resistance tests and detection of drug resistance gene expression were performed in MCF7 cells. Reduction in proliferation, as well as migration and colony formation, increased PARP-1 expression, inhibition of VEGF expression and cell cycle arrest in G2/M phase were displayed in the Circ-21 MCF7, which were not observed in the MCF10A cells. Furthermore, in the MCF7 cells, the Circ-21 enhanced the antitumor activity of doxorubicin and decreased the expression of resistance genes: ABCA1, ABCC4, and ABCC5. Based on these results, the use of Circ-21 can be considered a first step for the establishment of an effective gene therapy in the treatment of breast cancer.

Role of Nanotechnology in Overcoming the Multidrug Resistance in Cancer Therapy: A Review

Cancer is one of the leading causes of morbidity and mortality around the globe and is likely to become the major cause of global death in the coming years. As per World Health Organization (WHO) report, every year there are over 10 and 9 million new cases and deaths from this disease. Chemotherapy, radiotherapy, and surgery are the three basic approaches to treating cancer. These approaches are aiming at eradicating all cancer cells with minimum off-target effects on other cell types. Most drugs have serious adverse effects due to the lack of target selectivity. On the other hand, resistance to already available drugs has emerged as a major obstacle in cancer chemotherapy, allowing cancer to proliferate irrespective of the chemotherapeutic agent. Consequently, it leads to multidrug resistance (MDR), a growing concern in the scientific community. To overcome this problem, in recent years, nanotechnology-based drug therapies have been explored and have shown great promise in overcoming resistance, with most nano-based drugs being explored at the clinical level. Through this review, we try to explain various mechanisms involved in multidrug resistance in cancer and the role nanotechnology has played in overcoming or reversing this resistance.

The role and application of small extracellular vesicles in breast cancer

Breast cancer (BC) is the most common malignancy and the leading cause of cancer-related deaths in women worldwide. Currently, patients’ survival remains a challenge in BC due to the lack of effective targeted therapies and the difficult condition of patients with higher aggressiveness, metastasis and drug resistance. Small extracellular vesicles (sEVs), which are nanoscale vesicles with lipid bilayer envelopes released by various cell types in physiological and pathological conditions, play an important role in biological information transfer between cells. There is growing evidence that BC cell-derived sEVs may contribute to the establishment of a favorable microenvironment that supports cancer cells proliferation, invasion and metastasis. Moreover, sEVs provide a versatile platform not only for the diagnosis but also as a delivery vehicle for drugs. This review provides an overview of current new developments regarding the involvement of sEVs in BC pathogenesis, including tumor proliferation, invasion, metastasis, immune evasion, and drug resistance. In addition, sEVs act as messenger carriers carrying a variety of biomolecules such as proteins, nucleic acids, lipids and metabolites, making them as potential liquid biopsy biomarkers for BC diagnosis and prognosis. We also described the clinical applications of BC derived sEVs associated MiRs in the diagnosis and treatment of BC along with ongoing clinical trials which will assist future scientific endeavors in a more organized direction.

miRNAs as therapeutic predictors and prognostic biomarkers of neoadjuvant chemotherapy in breast cancer: a systematic review and meta-analysis

PURPOSE

Accumulating evidence has shown that microRNAs (miRNAs) are promising biomarkers of neoadjuvant chemotherapy (NAC) response in breast cancer (BC). However, their predictive roles remain controversial. Thus, this systematic review and meta-analysis aimed to describe the role of miRNA expression in NAC response and prognosis in BC to increase statistical power and improve translation.

METHODS

A systematic review of electronic databases for relevant studies was conducted following PRISMA guidelines. Data were extracted, collated, and combined by odds ratio (OR) and hazard ratio (HR) with 95% confidence intervals (CIs) to estimate the strength of the associations.

RESULTS

Of the 560 articles screened, 59 studies were included in our systematic review, and 5 studies were included in the subsequent meta-analysis. Sixty of 123 miRNAs were found to be related with NAC response and an elevated baseline miR-7 level in tissues was associated with a higher pathological complete response rate (OR 5.63; 95% CI 2.15-14.79; P = 0.0004). The prognostic value of 39 miRNAs was also studied. Of them, 26 miRNAs were found to be associated with survival. Pooled HRs indicated that patients with increased levels of serum miR-21 from baseline to the end of the second NAC cycle and from baseline to the end of NAC had a worse disease-free survival than those with decreased levels.

CONCLUSION

Our results highlight that a large number of miRNAs have possible associations with NAC response and prognosis in BC patients. Further well-designed studies are needed to elucidate the molecular mechanisms underlying these associations.

Dissecting the Roles of PDCD4 in Breast Cancer

The human programmed cell death 4 (PDCD4) gene was mapped at chromosome 10q24 and encodes the PDCD4 protein comprised of 469 amino acids. PDCD4 inhibits protein translation PDCD4 inhibits protein translation to suppress tumor progression, and its expression is frequently decreased in breast cancer. PDCD4 blocks translation initiation complex by binding eIF4A via MA-3 domains or by directly binding 5’ mRNA internal ribosome entry sites with an RNA binding domain to suppress breast cancer progression and proliferation. Numerous regulators and biological processes including non-coding RNAs, proteasomes, estrogen, natural compounds and inflammation control PDCD4 expression in breast cancer. Loss of PDCD4 expression is also responsible for drug resistance in breast cancer. HER2 activation downregulates PDCD4 expression by activating MAPK, AKT, and miR-21 in aromatase inhibitor-resistant breast cancer cells. Moreover, modulating the microRNA/PDCD4 axis maybe an effective strategy for overcoming chemoresistance in breast cancer. Down-regulation of PDCD4 is significantly associated with short overall survival of patients, which suggests that PDCD4 may be an independent prognostic marker for breast cancer.

Overview of MicroRNA Expression in Predicting Response to Neoadjuvant Therapies in Human Epidermal Growth Receptor-2 Enriched Breast Cancer - A Systematic Review

Purpose:

Increased appreciation of the human epidermal growth factor receptor-2 (HER2/neu) signalling pathway has led to the development of targeted therapeutic agents used in conjunction with chemotherapy to improve outcomes for HER2 overexpressing (HER2+) breast cancer. For neoadjuvant therapy, response rates can be unpredictable – novel biomarkers predicting effectiveness are required to enhance oncological outcomes for these patients, and microRNA may prove effective. Our objective was to identify microRNA (miRNA) expression patterns predictive of response to neoadjuvant chemotherapy (NAC) and/or anti-HER2 targeted therapies in patients being treated for early-stage HER2+ breast cancer.

Methods:

A search was performed of the PUBMED, SCOPUS, Web of Science, and EMBASE in accordance to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines.

Results:

Overall, 15 studies including 1335 patients were included. These studies highlighted an expression profile of 73 miRNA and their ability to predict tumour response to neoadjuvant therapies was correlated. Results from 11 studies were in relation to circulatory miRNA and 4 studies included data from tumour tissue. Overall, upregulation and downregulation of 41 miRNA and 29 miRNA, respectively, predicted differential response to neoadjuvant therapy. Expression levels of 3 miRNA (miR-21, miR-210, and miR-376c-3p) were inconclusive in predicting therapeutic response, while ‘aberrant’ expression of circulating miR-199a predicted pathological complete response (pCR) to NAC.

Conclusions:

This systematic review outlines expression patterns of a number of miRNA which correlate with response to NAC and/or anti-HER2 therapies. Future translational research evaluating predictive biomarkers of primary response to neoadjuvant therapy in HER2+ breast cancer may consider these results.

Small non-coding RNA profiling in breast cancer: plasma U6 snRNA, miR-451a and miR-548b-5p as novel diagnostic and prognostic biomarkers

BACKGROUND

Breast cancer is a leading cause of cancer-related death in women. Most cases are invasive ductal carcinomas of no special type (NST breast carcinomas).

METHODS AND RESULTS

In this prospective, multicentric biomarker discovery study, we analyzed the expression of small non-coding RNAs (mainly microRNAs) in plasma by qPCR and evaluated their association with NST breast cancer. Large-scale expression profiling and subsequent validations have been performed in patient and control groups and compared with clinicopathological data. Small nuclear U6 snRNA, miR-548b-5p and miR-451a have been identified as candidate biomarkers. U6 snRNA was remarkably overexpressed in all the validations, miR-548b-5p levels were generally elevated and miR-451a expression was mostly downregulated in breast cancer groups. Combined U6 snRNA/miR-548b-5p signature demonstrated the best diagnostic performance based on the ROC curve analysis with AUC of 0.813, sensitivity 73.1% and specificity 82.6%. There was a trend towards increased expression of both miR-548b-5p and U6 snRNA in more advanced stages. Further, increased miR-548b-5p levels have been partially associated with higher grades, multifocality, Ki-67 positivity, and luminal B rather than luminal A samples. On the other hand, an association has been observed between high miR-451a expression and progesterone receptor positivity, lower grade, unifocal samples, Ki-67-negativity, luminal A rather than luminal B samples as well as improved progression-free survival and overall survival.

CONCLUSIONS

Our results indicated that U6 snRNA and miR-548b-5p may have pro-oncogenic functions, while miR-451a may act as tumor suppressor in breast cancer.

Non-Coding RNAs in the Crosstalk between Breast Cancer Cells and Tumor-Associated Macrophages

Non-coding RNAs (ncRNAs) play a pivotal role in regulating the tumor microenvironment (TME) by controlling gene expression at multiple levels. In tumors, ncRNAs can mediate the crosstalk between cancer cells and other cells in the TME, such as immune cells, stromal cells, and endothelial cells, influencing tumor development and progression. Tumor-associated macrophages (TAMs) are among the most abundant inflammatory cells infiltrating solid cancers that promote tumorigenesis, and their infiltration correlates with a poor prognosis in many tumors. Cancer cells produce different ncRNAs that orchestrate TAM recruitment and polarization toward a tumor-promoting phenotype. Tumor-reprogrammed macrophages shape the TME by promoting angiogenesis and tissue remodeling, and suppressing the anti-tumor activity of adaptive immune cells. TAMs can also produce ncRNA molecules that boost cancer cell proliferation and direct their phenotype and metabolic changes facilitating cancer progression and metastasis. This review will focus on the crosstalk between cancer cells and TAMs mediated by microRNAs and long non-coding RNAs during breast cancer (BC) initiation and progression.

Diallyl disulfide and diallyl trisulfide in garlic as novel therapeutic agents to overcome drug resistance in breast cancer

Breast cancer is one of the leading causes of cancer-related deaths in women worldwide. It is a cancer that originates from the mammary ducts and involves mutations in multiple genes. Recently, the treatment of breast cancer has become increasingly challenging owing to the increase in tumor heterogeneity and aggressiveness, which gives rise to therapeutic resistance. Epidemiological, population-based, and hospital-based case-control studies have demonstrated an association between high intake of certain Allium vegetables and a reduced risk in the development of breast cancer. Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are the main allyl sulfur compounds present in garlic, and are known to exhibit anticancer activity as they interfere with breast cancer cell proliferation, tumor metastasis, and angiogenesis. The present review highlights multidrug resistance mechanisms and their signaling pathways in breast cancer. This review discusses the potential anticancer activities of DADS and DATS, with emphasis on drug resistance in triple-negative breast cancer (TNBC). Understanding the anticancer activities of DADS and DATS provides insights into their potential in targeting drug resistance mechanisms of TNBC, especially in clinical studies.

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The review describes the causes of drug resistance in TNBC.

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The effects of DADS and DATS on drug resistance mechanisms in TNBC are presented.

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The impacts of DADS and DATS on metastasis of TNBC are discussed.

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Antitumor immune activities of DADS and DATS against TNBC are illustrated.

The Role of Non-Coding RNAs in Breast Cancer Drug Resistance

Breast cancer (BC) is one of the commonly occurring malignancies in females worldwide. Despite significant advances in therapeutics, the mortality and morbidity of BC still lead to low survival and poor prognosis due to the drug resistance. There are certain chemotherapeutic, endocrine, and target medicines often used for BC patients, including anthracyclines, taxanes, docetaxel, cisplatin, and fluorouracil. The drug resistance mechanisms of these medicines are complicated and have not been fully elucidated. It was reported that non-coding RNAs (ncRNAs), such as micro RNAs (miRNA), long-chain non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) performed key roles in regulating tumor development and mediating therapy resistance. However, the mechanism of these ncRNAs in BC chemotherapeutic, endocrine, and targeted drug resistance was different. This review aims to reveal the mechanism and potential functions of ncRNAs in BC drug resistance and to highlight the ncRNAs as a novel target for achieving improved treatment outcomes for BC patients.

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.

The Role of MicroRNA as Clinical Biomarkers for Breast Cancer Surgery and Treatment

Breast cancer is the most common cancer diagnosed in women. In recent times, survival outcomes have improved dramatically in accordance with our enhanced understanding of the molecular processes driving breast cancer proliferation and development. Refined surgical approaches, combined with novel and targeted treatment options, have aided the personalisation of breast cancer patient care. Despite this, some patients will unfortunately succumb to the disease. In recent times, translational research efforts have been focused on identifying novel biomarkers capable of informing patient outcome; microRNAs (miRNAs) are small non-coding molecules, which regulate gene expression at a post-transcriptional level. Aberrant miRNA expression profiles have been observed in cancer proliferation and development. The measurement and correlation of miRNA expression levels with oncological outcomes such as response to current conventional therapies, and disease recurrence are being investigated. Herein, we outline the clinical utility of miRNA expression profiles in informing breast cancer prognosis, predicting response to treatment strategies as well as their potential as therapeutic targets to enhance treatment modalities in the era of precision oncology.

Epithelial to Mesenchymal Transition History: From Embryonic Development to Cancers

Epithelial to mesenchymal transition (EMT) is a process that allows epithelial cells to progressively acquire a reversible mesenchymal phenotype. Here, we recount the main events in the history of EMT. EMT was first studied during embryonic development. Nowadays, it is an important field in cancer research, studied all around the world by more and more scientists, because it was shown that EMT is involved in cancer aggressiveness in many different ways. The main features of EMT's involvement in embryonic development, fibrosis and cancers are briefly reviewed here.

Hsa-miR-107 regulates chemosensitivity and inhibits tumor growth in hepatocellular carcinoma cells

Hepatocellular carcinoma is a common type of liver cancer. Resistance to chemotherapeutic agents is a major problem in cancer therapy. MicroRNAs have been reported in cancer development and tumor growth; however, the relationship between chemoresistance and hepatocellular carcinoma needs to be fully investigated. Here, we treated hepatocellular carcinoma cell line (HA22T) with a histone deacetylase inhibitor to establish hepatocellular carcinoma-resistant cells (HDACi-R) and investigated the molecular mechanisms of chemoresistance in HCC cells. Although histone deacetylase inhibitor could not enhance cell death in HDACi-R but upregulation of miR-107 decreased cell viability both in parental cells and resistance cells, decreased the expression of cofilin-1, enhanced ROS-induced cell apoptosis, and dose-dependently sensitized HDACi-R to HDACi. Further, miR-107 upregulation resulted in tumor cell disorganization in both HA22T and HDACi-R in a mice xenograft model. Our findings demonstrated that miR-107 downregulation leads to hepatocellular carcinoma cell resistance in HDACi via a cofilin-1-dependent molecular mechanism and ROS accumulation.

Cancer stem cell-targeted therapeutic approaches for overcoming trastuzumab resistance in HER2-positive breast cancer

Application of the anti-HER2 drug trastuzumab has significantly improved the prognosis of patients with the HER2-positive subtype of breast cancer. However, 50% of patients with HER2 amplification relapse due to trastuzumab resistance. Accumulating evidence indicates that breast cancer is driven by a small subset of cancer-initiating cells or breast cancer stem cells (BCSCs), which have the capacity to self-renew and differentiate to regenerate the tumor cell hierarchy. Increasing data suggest that BCSCs are resistant to conventional therapy, including chemotherapy, radiotherapy, and endocrine therapy, which drives distant metastasis and breast cancer relapse. In recent years, the trastuzumab resistance of breast cancer has been closely related to the prevalence of BCSCs. Here, our primary focus is to discuss the role of epithelial-mesenchymal transition (EMT) of BCSCs in the setting of trastuzumab resistance and approaches of reducing or eradicating BCSCs in HER2-positive breast cancer.

Curcumin-enhanced antitumor effects of sorafenib via regulating the metabolism and tumor microenvironment

Curcumin, the main active ingredient of turmeric, is widely used as a kind of food additive and also displays a range of pharmacological activities, such as anti-inflammation, anti-tumor, liver and kidney protection, and so forth. Sorafenib was the first targeted agent against hepatocellular carcinoma (HCC), whose intolerance is related to the promotion of lipid synthesis and epithelial-to-mesenchymal transition (EMT) formation. In this study, biochemical analysis, immune cells composition, the tumor microenvironment, metabolomics, and relative metabolic enzymes and transporters were detected in H22-bearing mice treated with curcumin combined with sorafenib vs. control groups. It was found that curcumin protected against liver cancer progression through reducing the level of alpha fetoprotein in liver tissues, increasing the number of immune cells, like NK cells, inhibiting EMT via the regulation of IL-6/JAK/STAT3 and IL-1β/NF-κB pathways, suppressing anaerobic glycolysis through the inhibition of LDH and HIF-1α, and decreasing the lipid synthesis via the downregulation of FASN, and upregulated the serum HDL-C and mRNA levels of apoA1 in the sorafenib-treated mice. Furthermore, curcumin regulation of the disorder of glycolipid metabolism and EMT was also based on the PI3K/AKT pathway. A docking study was performed and proved the strong affinity between curcumin and the proteins of STAT3, FASN, and AKT. All in all, this experiment provided evidence for the addition of curcumin in the diet to enhance the antitumor efficacy of sorafenib through activating immune function, downregulating EMT, and reversing disorders of the metabolism.

Regulation of microRNA-21 expression by natural products in cancer

Natural products have been of much interest in research studies owing to their wide pharmacological applications, chemical diversity, low side effects, and multitarget activities. Examples of these compounds include matrine, sulforaphane, silibinin, curcumin, berberin, resveratrol, and quercetin. Some of the present anticancer drugs, such as taxol, vincristine, vinblastine, and doxorubicin are also derived from natural products. The anti-carcinogenic effects of these products are partly mediated through modulation of microRNA-21 (miR-21) expression. To date, numerous downstream targets of miR-21 have been recognized, which include phosphatase and tensin homolog (PTEN), ras homolog gene family member B (RHOB), phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), programmed cell death 4 (PDCD4), signal transducer and activator of transcription (STAT)-3, and nuclear factor kappa B (NF-κB) pathways. These signaling pathways, their regulation by oncomiR-21 in cancer, and the modulating impact of natural products are the main focus of this review.

miR-21 Plays a Dual Role in Tumor Formation and Cytotoxic Response in Breast Tumors

Simple Summary

miR-21 is an oncogenic microRNA that has been associated with breast tumor growth and metastasis in vitro and is also noted to be upregulated by cytotoxic stressors in model systems and in breast cancer patients who have undergone radiation. In the present study, our findings demonstrate the novel role of miR-21 in vivo for breast cancer initiation and metastases, and in sensitizing tumor cells to cytotoxic therapy by upregulating the FAS/FASL signaling pathway.

Abstract

Breast cancer (BrCa) relies on specific microRNAs to drive disease progression. Oncogenic miR-21 is upregulated in many cancers, including BrCa, and is associated with poor survival and treatment resistance. We sought to determine the role of miR-21 in BrCa tumor initiation, progression and treatment response. In a triple-negative BrCa model, radiation exposure increased miR-21 in both primary tumor and metastases. In vitro, miR-21 knockdown decreased survival in all BrCa subtypes in the presence of radiation. The role of miR-21 in BrCa initiation was evaluated by implanting wild-type miR-21 BrCa cells into genetically engineered mouse models where miR-21 was intact, heterozygous or globally ablated. Tumors were unable to grow in the mammary fat pads of miR-21^−/− mice, and grew in ~50% of miR-21^+/− and 100% in miR-21^+/+ mice. The contribution of miR-21 to progression and metastases was tested by crossing miR-21^−/− mice with mice that spontaneously develop BrCa. The global ablation of miR-21 significantly decreased the tumorigenesis and metastases of BrCa, while sensitizing tumors to radio- and chemotherapeutic agents via Fas/FasL-dependent apoptosis. Therefore, targeting miR-21 alone or in combination with various radio or cytotoxic therapies may represent novel and efficacious therapeutic modalities for the future treatment of BrCa patients.

Endoplasmic reticulum stress and oncomir-associated chemotherapeutic drug resistance mechanisms in breast cancer tumors

Breast cancer, as a heterogenous malign disease among the top five leading causes of cancer death worldwide, is defined as by far the most common malignancy in women. It contributes to 25% of all cancer-associated deaths after menopause. Breast cancer is categorized based on the expression levels of cell surface and intracellular steroid receptors [estrogen, progesterone receptors, and human epidermal growth factor receptor (HER2)], and the treatment approaches frequently include antiestrogen, aromatase inhibitors, and Herceptin. However, the management and prevention strategies due to adverse side effects stress the patients. The unsuccessful treatments cause to raise the drug levels, leading to excessive toxic effects on healthy cells, and the development of multidrug-resistance (MDR) in the tumor cells against chemotherapeutic agents. MDR initially causes the tumor cells to gain a metastatic character, and subsequently, the patients do not respond adequately to treatment. Endoplasmic reticulum (ER) stress is one of the most important mechanisms supporting MDR development. ER stress-mediated chemotherapeutic resistance is very common in aggressive tumors. The in vitro and in vivo experiments on breast tumors indicate that ER stress-activated protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)- activating transcription factor (ATF4) signal axis plays an important role in the survival of tumors and metastasis. Besides, ER stress-associated oncogenic microRNAs (miRNAs) induce chemoresistance in breast tumors. We aimed to have a look at the development of resistance mechanisms due to ER stress as well as the involvement of ER stress-associated miRNA regulation following the chemotherapeutic regimen in the human breast tumors. We also aimed to draw attention to potential molecular markers and therapeutic targets.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

Triple negative breast cancer in the era of miRNA

The objective of this review is to elucidate the role of miRNAs in triple negative breast cancer (TNBC). To achieve our goal, we searched databases such as PubMed, ScienceDirect, Springer, Web of Science and Scopus. We retrieved up to 1233 articles, based a rigorous selection criterion, only 197 articles were extensively reviewed. We selected articles only addressing TNBC, but not other types of breast cancer, with the employed approach being miRNA analysis and/or profiling. Our extensive review resulted in grouping of miRNAs into categories in which specific members of miRNAs have roles in specific mechanism in TNBC i.e., carcinogenesis, invasion, metastasis, apoptosis, diagnosis, prognosis, and treatment. TNBC is an aggressive subtype of breast cancer; therefore, different approaches for accurate diagnosis, prognosis and treatment are needed. In this review we summarize the up-to-date miRNA profiling, prognostic, and therapeutic findings that add to the route of controlling TNBC.

Cancer-Associated Stemness and Epithelial-to-Mesenchymal Transition Signatures Related to Breast Invasive Carcinoma Prognostic

Simple Summary

Breast cancer is one of the most common oncological diseases in women, as its incidence is rapidly growing. In this study, we have investigated the mechanism of epithelial-to-mesenchymal transition (EMT) and cancer stem cells (CSCs), demonstrating presence of an interconnectedness between them. This interconnectedness plays important roles in patient prognostic, as well as in diagnostic and therapeutic targets. It is identified that there is a common signature between CSCs and EMT, and this is represented by ALDH1A1, SFRP1, miR-139, miR-21, and miR-200c. This finding will provide a better understanding of this mechanism, and will facilitate the development of novel treatment options.

Abstract

Breast cancer is one of the most common oncological diseases in women, as its incidence is rapidly growing, rendering it unpredictable and causing more harm than ever before on an annual basis. Alterations of coding and noncoding genes are related to tumorigenesis and breast cancer progression. In this study, several key genes associated with epithelial-to-mesenchymal transition (EMT) and cancer stem cell (CSC) features were identified. EMT and CSCs are two key mechanisms responsible for self-renewal, differentiation, and self-protection, thus contributing to drug resistance. Therefore, understanding of the relationship between these processes may identify a therapeutic vulnerability that can be further exploited in clinical practice, and evaluate its correlation with overall survival rate. To determine expression levels of altered coding and noncoding genes, The Cancer Omics Atlas (TCOA) are used, and these data are overlapped with a list of CSCs and EMT-specific genes downloaded from NCBI. As a result, it is observed that CSCs are reciprocally related to EMT, thus identifying common signatures that allow for predicting the overall survival for breast cancer genes (BRCA). In fact, common CSCs and EMT signatures, represented by ALDH1A1, SFRP1, miR-139, miR-21, and miR-200c, are deemed useful as prognostic biomarkers for BRCA. Therefore, by mapping changes in gene expression across CSCs and EMT, suggesting a cross-talk between these two processes, we have been able to identify either the most common or specific genes or miRNA markers associated with overall survival rate. Thus, a better understanding of these mechanisms will lead to more effective treatment options.

Connecting the Missing Dots: ncRNAs as Critical Regulators of Therapeutic Susceptibility in Breast Cancer

Whether acquired or de novo, drug resistance remains a significant hurdle in achieving therapeutic success in breast cancer (BC). Thus, there is an urge to find reliable biomarkers that will help in predicting the therapeutic response. Stable and easily accessible molecules such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are regarded as valuable prognostic biomarkers and therapeutic targets since they act as crucial regulators of the various mechanisms involved in BC drug resistance. Here, we reviewed the current literature on ncRNAs as mediators of resistance to systemic therapies in BC. Interestingly, upon integrating data results from individual studies, we concluded that miR-221, miR-222, miR-451, Urothelial Carcinoma Associated 1 (UCA1), and Growth arrest-specific 5 (GAS5) are strong candidates as prognostic biomarkers and therapeutic targets since they are regulating multiple drug resistance phenotypes in BC. However, further research around their clinical implications is needed to validate and integrate them into therapeutic applications. Therefore, we believe that our review may provide relevant evidence for the selection of novel therapeutic targets and prognostic biomarkers for BC and will serve as a foundation for future translational research in the field.

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.

Mechanisms of Multidrug Resistance in Cancer Chemotherapy

Cancer is one of the main causes of death worldwide. Despite the significant development of methods of cancer healing during the past decades, chemotherapy still remains the main method for cancer treatment. Depending on the mechanism of action, commonly used chemotherapeutic agents can be divided into several classes (antimetabolites, alkylating agents, mitotic spindle inhibitors, topoisomerase inhibitors, and others). Multidrug resistance (MDR) is responsible for over 90% of deaths in cancer patients receiving traditional chemotherapeutics or novel targeted drugs. The mechanisms of MDR include elevated metabolism of xenobiotics, enhanced efflux of drugs, growth factors, increased DNA repair capacity, and genetic factors (gene mutations, amplifications, and epigenetic alterations). Rapidly increasing numbers of biomedical studies are focused on designing chemotherapeutics that are able to evade or reverse MDR. The aim of this review is not only to demonstrate the latest data on the mechanisms of cellular resistance to anticancer agents currently used in clinical treatment but also to present the mechanisms of action of novel potential antitumor drugs which have been designed to overcome these resistance mechanisms. Better understanding of the mechanisms of MDR and targets of novel chemotherapy agents should provide guidance for future research concerning new effective strategies in cancer treatment.

Role of exosomal miR‑21 in the tumor microenvironment and osteosarcoma tumorigenesis and progression (Review)

Osteosarcoma is the most common bone tumor affecting both adolescents and children. Early detection is critical for the effective treatment of the disease. Derived from cancer cells, miR‑21 contained within exosomes in the tumor microenvironment may act on both cancer cells and the surrounding tumor microenvironment (TME), including immune cells, endothelial cells and fibroblasts. In human serum and plasm, the level of exosomal miR‑21 between osteosarcoma patients and healthy controls differs, supporting the role of miR‑21 as a biomarker for osteosarcoma. The involvement of a number of miR‑21 target genes in tumor progression suggests that miR‑21 may significantly affect the plasticity of cancer cells, leading to tumor progression, metastasis, angiogenesis and immune escape in osteosarcoma. Understanding the biogenesis and functions of exosomal miR‑21 is of great value for the diagnosis and therapy of cancer, including osteosarcoma. The present review discusses the role of miR‑21 in the tumor microenvironment, and in the development and progression of osteosarcoma, with an aim to summarize the functions of this miRNA in cancer.

Associations Between miRNAs and Two Different Cancers: Breast and Colon

Objective

Screening approaches using microRNAs (miRNAs) have been gaining increased attention owing to their potential applications in the diagnosis, prognosis, and monitoring of cancer, because aberrant miRNA expression plays a role in the development and advancement of malignancies. The objectives of this study were to characterize mir21, miR31, mir143, mir145, and control RNU43, which are differentially expressed in peripheral blood mononuclear cells (PBMCs) of breast and colorectal cancer patients, compared to that in controls and to establish whether this is specific to breast and colon cancer for use as tumor markers.

Methods

Thirty newly diagnosed patients with breast cancer and 30 patients with colorectal cancer were enrolled together with 30 healthy controls. PBMCs were isolated from venous blood samples of individuals. Next, miRNA expression analysis was performed by a two-step method of reverse transcription and qPCR.

Results

The expression levels of miR-143 and miR-31 were significantly decreased, whereas the expression levels of miR-145 and miR-21 were significantly increased in breast cancer patients compared to those in healthy subjects. Moreover, the expression levels of miR-143, miR-145, and miR-21 were significantly increased and, in contrast, the changes in the expression levels of miR-31 were not statistically significant in colon cancer compared to those in healthy subjects. miR-21 exhibited the highest increase in both breast and colon cancers. There was a weak positive correlation between miR-145 and CA-15.3 in patients with breast cancer (r = 0.451; p = 0.012). miR-143 was positively correlated with the TNM stage in colon cancer patients (r = 0.568; p = 0.001).

Conclusion

A biomarker panel composed of miR-21, miR-31, miR-143, and miR-145 in PBMC may provide a new diagnostic approach for the early detection of breast and colon cancer. As miR-21 expression was found to be the highest among all the miRNAs evaluated, it may represent a new tumor biomarker and a candidate therapeutic drug or gene target in colon and breast cancer.

Role of miR-21 as an authentic oncogene in mediating drug resistance in breast cancer

Breast cancer (BC) is the most common cancer among women that is responsible for the most of the cancer-related death in worldwide. Drug resistance is remaining as a significant clinical obstacle to treat BC patients effectively. Therefore, to help overcome this problem, it is necessary to understand the mechanisms of drug resistance. microRNAs classify as highly conserved non-coding RNAs (~22 nucleotides) and interact with mRNAs-coding genes for direct post-transcriptional repression. It has been reported that miR-21 is overexpressed and also acts as oncomiR in many human malignancies by targeting of several tumor suppressor genes-associated with apoptosis, proliferation and metastasis. Specifically, it has been reported that miR-21 is responsible for the drug resistance and its overexpression is related to the development of Multi Drug Resistance (MDR) in breast cancer. In this review, we discussed about the role of miR-21 on the drug resistance of breast cancer.

Role of JAK/STAT3 Signaling in the Regulation of Metastasis, the Transition of Cancer Stem Cells, and Chemoresistance of Cancer by Epithelial-Mesenchymal Transition

The JAK/STAT3 signaling pathway plays an essential role in various types of cancers. Activation of this pathway leads to increased tumorigenic and metastatic ability, the transition of cancer stem cells (CSCs), and chemoresistance in cancer via enhancing the epithelial–mesenchymal transition (EMT). EMT acts as a critical regulator in the progression of cancer and is involved in regulating invasion, spread, and survival. Furthermore, accumulating evidence indicates the failure of conventional therapies due to the acquisition of CSC properties. In this review, we summarize the effects of JAK/STAT3 activation on EMT and the generation of CSCs. Moreover, we discuss cutting-edge data on the link between EMT and CSCs in the tumor microenvironment that involves a previously unknown function of miRNAs, and also discuss new regulators of the JAK/STAT3 signaling pathway.

Nanotechnology, in silico and endocrine-based strategy for delivering paclitaxel and miRNA: Prospects for the therapeutic management of breast cancer

Breast cancer is one of the most prevalent and reoccurring cancers and the second most common reason of death in women. Despite advancements in therapeutic strategies for breast cancer, early tumor recurrence and metastasis in patients indicate resistance to chemotherapeutic medicines, such as paclitaxel due to the abnormal expression of ER and EGF2 in breast cancer cells. Therefore, the development of alternatives to paclitaxel is urgently needed to overcome challenges involving drug resistance. An increasing number of studies has revealed miRNAs as novel natural alternative substances that play a crucial role in regulating several physiological processes and have a close, adverse association with several diseases, including breast cancer. Due to the therapeutic potential of miRNA and paclitaxel in cancer research, the current review focuses on the differential roles of various miRNAs in breast cancer development and treatment. miRNA delivery to a specific target site, the development of paclitaxel and miRNA formulations, and nanotechnological strategies for the delivery of nanopaclitaxel in the management of breast cancer are discussed. These strategies involve improving the cellular uptake and bioavailability and reducing the toxicity of free paclitaxel to achieve accumulation tumor site. Furthermore, a molecular docking study was performed to ascertain the enhanced anticancer activity of the nanoformulation of ANG1005 and Abraxane. An in silico analysis revealed that ANG1005 and Abraxane nanoformulations have superior and significantly enhanced interactions with the proteins α-tubulin and Bcl-2. Therefore, ANG1005 and Abraxane may be more suitable in the therapeutic management of breast cancer than the existing free paclitaxel. miRNAs can revert abnormal gene expression to normalcy; since miRNAs serve as tumor suppressors. Therefore, restoration of particular miRNAs levels as a replacement therapy may be an effective endocrine potential strategy for treating ER positive/ negative breast cancers.

MicroRNAs Involved in Carcinogenesis, Prognosis, Therapeutic Resistance and Applications in Human Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive, prevalent, and distinct subtype of breast cancer characterized by high recurrence rates and poor clinical prognosis, devoid of both predictive markers and potential therapeutic targets. MicroRNAs (miRNA/miR) are a family of small, endogenous, non-coding, single-stranded regulatory RNAs that bind to the 3′-untranslated region (3′-UTR) complementary sequences and downregulate the translation of target mRNAs as post-transcriptional regulators. Dysregulation miRNAs are involved in broad spectrum cellular processes of TNBC, exerting their function as oncogenes or tumor suppressors depending on their cellular target involved in tumor initiation, promotion, malignant conversion, and metastasis. In this review, we emphasize on masses of miRNAs that act as oncogenes or tumor suppressors involved in epithelial–mesenchymal transition (EMT), maintenance of stemness, tumor invasion and metastasis, cell proliferation, and apoptosis. We also discuss miRNAs as the targets or as the regulators of dysregulation epigenetic modulation in the carcinogenesis process of TNBC. Furthermore, we show that miRNAs used as potential classification, prognostic, chemotherapy and radiotherapy resistance markers in TNBC. Finally, we present the perspective on miRNA therapeutics with mimics or antagonists, and focus on the challenges of miRNA therapy. This study offers an insight into the role of miRNA in pathology progression of TNBC.

Improving the therapeutic efficiency of noncoding RNAs in cancers using targeted drug delivery systems

The delivery of noncoding (nc)RNA to target cancer stem cells and metastatic tumors has shown many positive outcomes, resulting in improved and more efficient treatment strategies. The success of therapeutic RNA depends solely on passing cellular barriers to reach the target site, where it binds to the mRNA of the interest. By 2018, 20 clinical trials had been initiated, most focusing on cancer and diabetes, with some progressing to Phase II clinical trials testing the safety and efficacy of small interfering (si)RNA. Many challenges limit RNA interference (RNAi) and miRNA usage in vivo; therefore, various approaches have been developed to promote ncRNA efficiency and stability. In this review, we focus on targeting the tumor microenvironment (TME) via the modification of delivery systems utilizing nanotechnology-based delivery approaches.