Cross-Roads to Drug Resistance and Metastasis in Breast Cancer: miRNAs Regulatory Function and Biomarker Capability

Assessment of breast cytoarchitecture and its associated axillary lymph node status under normal and pathological conditions in Egyptian women

OBJECTIVE

Herein, we compare the features of neoplastic cancer cells in invasive ductal carcinoma (IDC) grade II and III patients to their corresponding normal cells both in breast and axillary lymph node (ALN) tissues.

METHODS

A retrospective cohort of 70 female breast cancer patients enrolled between 2018 and 2020 at Medical Research Institute, Alexandria University, Egypt, was analyzed for clinicopathological features presentation. Fresh tiny pieces of breast tissue and its associated ALN tissues were then processed to investigate the morphological appearance by scanning electron microscopy. Moreover, the histological architecture of tissue sections stained with hematoxylin and eosin was studied by light microscope, while the characterization of the ultrastructure features of breast and ALN tissues was analyzed by transmission electron microscopy.

RESULTS

Clinicopathological presentation of patients revealed that the Egyptian female breast cancer population adhered to the global trends of breast cancer disease with elevated incidence rate among postmenopausal women (61.3%), high frequency of IDC (95.7%), and increased ALN metastasis (65.7%). The percentage of estrogen receptor alpha (ERα) and human epidermal growth factor receptor 2 (HER2) expression, as key indicators for carcinogenesis and disease progression was 87.1% and 55.8%, respectively. The present study points to the observed discrepancies among the investigated variables in the diagnostic separation between IDC grade II and grade III. Ductal epithelial cells organization, nuclei size and irregularity, chromatin amount and uniformity, mitochondrial abundance and dysfunction were differentially manifested in IDC grades. Moreover, aberrations in the cellular organelles like lysosomes, endoplasmic reticulum, and lipid droplets vary according to the grade of IDC and the aggressiveness of the invasive breast cancer.

CONCLUSIONS

To sum up, this study emphasizes the importance of accurate specimen evaluation for treatment choice and decision.

In Vitro microRNA Expression Profile Alterations under CDK4/6 Therapy in Breast Cancer

BACKGROUND

Breast cancer is the most common type of cancer worldwide. Cyclin-dependent kinase inhibition is one of the backbones of metastatic breast cancer therapy. However, there are a significant number of therapy failures. This study evaluates the biomarker potential of microRNAs for the prediction of a therapy response under cyclin-dependent kinase inhibition.

METHODS

This study comprises the analysis of intracellular and extracellular microRNA-expression-level alterations of 56 microRNAs under palbociclib mono as well as combination therapy with letrozole. Breast cancer cell lines BT-474, MCF-7 and HS-578T were analyzed using qPCR.

RESULTS

A palbociclib-induced microRNA signature could be detected intracellularly as well as extracellularly. Intracellular miR-10a, miR-15b, miR-21, miR-23a and miR-23c were constantly regulated in all three cell lines, whereas let-7b, let-7d, miR-15a, miR-17, miR-18a, miR-20a, miR-191 and miR301a_3p were regulated only in hormone-receptor-positive cells. Extracellular miR-100, miR-10b and miR-182 were constantly regulated across all cell lines, whereas miR-17 was regulated only in hormone-receptor-positive cells.

CONCLUSIONS

Because they are secreted and significantly upregulated in the microenvironment of tumor cells, miRs-100, -10b and -182 are promising circulating biomarkers that can be used to predict or detect therapy responses under CDK inhibition. MiR-10a, miR-15b, miR-21, miR-23a and miR-23c are potential tissue-based biomarkers.

Over-expression of miR-183-5p or miR-492 triggers invasion and proliferation and loss of polarity in non-neoplastic breast epithelium

microRNAs (miRNAs) serve as novel noninvasive cancer biomarkers. In an HMT-3522 S1 (S1) breast epithelial risk-progression three-dimensional (3D) culture model, non-neoplastic S1 cells form a fully polarized epithelium. When silenced for the gap junction and tumor suppressor Cx43, Cx43-KO-S1 cells recapitulate pre-neoplastic phenotypes observed in tissues at risk for breast cancer in vivo. To delineate the role of miRNAs in breast tumorigenesis and identify key miRNA players in breast epithelial polarity, the miRNA profile specific to Cx43 loss in Cx43-KO-S1 compared to S1 cells was sequenced, revealing 65 differentially expressed miRNAs. A comparative analysis was conducted between these miRNAs and tumor-associated miRNAs from a young Lebanese patient validation cohort. miR-183-5p, downstream of Cx43 loss, was commonly upregulated in the patient cohort and the 3D culture model. miR-492, not attributed to Cx43 loss, was only specifically up-regulated in the young Lebanese patients. Ectopic expression of either miR-183-5p or miR-492 in S1 cells, through pLenti-III-miR-GPF vectors, resulted in the formation of larger multi-layered acini devoid of lumen, with disrupted epithelial polarity, as shown by an altered localization of Cx43, ß-catenin and Scrib, and decreased nuclear circularity in 3D cultures. Enhanced proliferation and invasion capacity were also observed. Over-expression of miR-183-5p or miR-492, therefore, induces pre-neoplastic phenotypes similar to those reported upon Cx43 loss, and may act as oncomiRs and possible biomarkers of increased breast cancer risk.

METTL3/LINC00662/miR-186-5p feedback loop regulates docetaxel resistance in triple negative breast cancer

Insight into the mechanism of docetaxel resistance in breast cancer may help to improve prognosis. We aimed to investigate the role of N6-methyladenosine (m6A) and the METTL3/LINC00662/miR-186-5p pathway in regulating docetaxel resistance in triple negative breast cancer (TNBC). We have recruited 193 pathologically diagnosed TNBC patients from 2016 to 2017 in our hospital. Quantitative real-time PCR was used to evaluate the expression of LINC00662 and miR-186-5p both in vivo and in vitro. CCK8 tests were used to assess cell viability. ELISA was used for protein expression evaluation. Dual luciferase reporter gene assay and RNA pull-down were used to evaluate the interaction between LINC00662 and miR-186-5p. m6A levels were enhanced in breast cancer tissues and cells. LINC00662, miR-186-5p and METTL3 were differentially expressed in vivo, and METTL3 expression was associated with LINC00662 and miR-186-5p expression. LINC00662 and miR-186-5p were differentially expressed in vitro; LINC00662 promoted cell viability and decreased the apoptosis rate, whereas miR-186-5p inhibited cell viability and increased the apoptosis rate. Furthermore, we found that METTL3 regulated m6A levels in docetaxel-resistant breast cancer cells by regulating the expression of LINC00662. Moreover, LINC00662 and miR-186-5p regulated the cell viability rate of docetaxel-resistant breast cancer cells. Further experiments showed that LINC00662 directly interacted with miR-186-5p to exert biological functions; besides miR-186-5p could regulate the expression of METTL3. METTL3 promotes m6A levels and docetaxel resistance in breast cancer by regulating the expression of LINC00662 and miR-186-5p; more experiments are needed to clarify the role of m6A regulation in drug resistance.

Silencing long non-coding RNA HNF1A-AS1 inhibits growth and resistance to TAM of breast cancer cells via the microRNA-363/SERTAD3 axis

Long non-coding RNAs (lncRNAs) can exert effects on drug resistance of cancer cells. This study investigated the role of lncRNA HNF1A-antisense 1 (HNF1A-AS1) in growth and Tamoxifen (TAM) sensitivity of breast cancer (BC) cells. HNF1A-AS1 expression was promoted in BC cells and tissues. BC cells with HNF1A-AS1 silencing were constructed to detect cell proliferation. TAM resistant cell line with HNF1A-AS1 silencing and parent cell line with overexpressed HNF1A-AS1 were constructed to measure drug resistance. Silencing HNF1A-AS1 reduced proliferation and TAM resistance of BC cells. The downstream microRNAs (miRs) of HNF1A-AS1 and its targets were figured out and their functions in TAM resistance of BC cells were identified. HNF1A-AS1 sponged miR-363 to promote SERTAD3 expression. Downregulation of miR-363 or upregulation of SERTAD3 stimulated TAM resistance of BC cells. The findings in vitro were reproduced in in vivo experiments. It could be concluded that silencing HNF1A-AS1 inhibited growth and drug resistance to TAM of BC cells through the miR-363/SERTAD3 axis and the inactivation of the TGF-β/Smad pathway.

A risk progression breast epithelial 3D culture model reveals Cx43/hsa_circ_0077755/miR-182 as a biomarker axis for heightened risk of breast cancer initiation

mRNA-circRNA-miRNAs axes have been characterized in breast cancer, but not as risk-assessment axes for tumor initiation in early-onset breast cancer that is increasing drastically worldwide. To address this gap, we performed circular RNA (circRNA) microarrays and microRNA (miRNA) sequencing on acini of HMT-3522 S1 (S1) breast epithelial risk-progression culture model in 3D and chose an early-stage population miRNome for a validation cohort. Nontumorigenic S1 cells form fully polarized epithelium while pretumorigenic counterparts silenced for gap junction Cx43 (Cx43-KO-S1) lose epithelial polarity, multilayer and mimic premalignant in vivo mammary epithelial morphology. Here, 121 circRNAs and 65 miRNAs were significantly dysregulated in response to Cx43 silencing in cultured epithelia and 15 miRNAs from the patient cohort were involved in epithelial polarity disruption. Focusing on the possible sponging activity of the validated circRNAs to their target miRNAs, we found all miRNAs to be highly enriched in cancer-related pathways and cross-compared their dysregulation to actual miRNA datasets from the cultured epithelia and the patient validation cohort. We present the involvement of gap junction in post-transcriptional axes and reveal Cx43/hsa_circ_0077755/miR-182 as a potential biomarker signature axis for heightened-risk of breast cancer initiation, and that its dysregulation patterns might predict prognosis along breast cancer initiation and progression.

METTL3 promotes adriamycin resistance in MCF-7 breast cancer cells by accelerating pri-microRNA-221-3p maturation in a m6A-dependent manner

Breast cancer (BC) is the most prevalent malignant neoplasm among women and is the fifth most common cause of cancer-associated death worldwide. Acquired chemoresistance driven by genetic and epigenetic alterations is a significant clinical challenge in treating BC. However, the mechanism of BC cell resistance to adriamycin (ADR) remains to be elucidated. In this study, we identified the methyltransferase-like 3/microRNA-221-3p/homeodomain-interacting protein kinase 2/Che-1 (METTL3/miR-221-3p/HIPK2/Che-1) axis as a novel signaling event that may be responsible for resistance of BC cells to ADR. A dual-luciferase reporter gene assay was employed to test the presence of miR-221-3p binding sites in the 3'UTR of HIPK2. Drug resistance was evaluated by immunoblotting multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP). Cultured ADR-resistant MCF-7 cells were assayed for their half maximal inhibitory concentration (IC50) values and apoptosis using an MTT assay and Annexin V-FITC/PI-labeled flow cytometry, and the cells were then xenografted into nude mice. METTL3 knockdown was shown to reduce the expression of miR-221-3p by reducing pri-miR-221-3p m6A mRNA methylation, thereby reducing the IC50 value of ADR-resistant MCF-7 cells, reducing the expression of MDR1 and BCRP, and inducing apoptosis. Mechanistically, miR-221-3p was demonstrated to negatively regulate HIPK2 and upregulate its direct target Che-1, thus leading to enhanced drug resistance in ADR-resistant MCF-7 cells. In vitro results were reproduced in nude mice xenografted with ADR-resistant MCF-7 cells. Our work elucidates an epigenetic mechanism of acquired chemoresistance in BC, in support of the METTL3/miR-221-3p/HIPK2/Che-1 axis as a therapeutic target for the improvement of chemotherapy.

RETRACTED: LncRNA GAS6-AS1 facilitates the progression of breast cancer by targeting the miR-324-3p/SETD1A axis to activate the PI3K/AKT pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the current Editor in Chief, with the agreement of all authors. The article is being retracted due to inappropriate manipulation of the original data for presentation in Figures 2C, 5C and 6C. Upon further investigation and discussion with the authors, insufficient evidence was provided to support a reasonable explanation for these mistakes. In addition, the authors could not provide convincing original data supporting other figures of the manuscript, e.g. Figures 2G, 4 and 6A. Based on these findings, the Editor in Chief and the authors have decided to retract the study. The authors apologize for any inconvenience caused.

Characterizing the Relapse Potential in Different Luminal Subtypes of Breast Cancers with Functional Proteomics

Poor prognosis due to the high relapse and metastasis rates of breast cancer has been particularly linked to the luminal B subtype. The current study utilized MCF-7 and ZR-75-1 to investigate various luminal subtypes of breast cancers that have discrepant expressions in the estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2). Understanding of the differential protein profiles and the associated pathways could help alleviate the malignance and promote the long-term survival rate of breast cancer patients. Functional proteome tools were applied to comprehensively delineate the global protein alterations that reflect the varieties of biological features between the two subtypes. In this study, a total of 11 proteins with significant and meaningful changes were identified. These protein targets including PRX2, CK19, nucleophosmin and cathepsin D were mostly involved in cell differentiation or proliferation. Particularly, cathepsin D was highly expressed in the luminal B subtype. Moreover, the level of cathepsin-D was also upregulated in the clinical metastatic tissues. Accordingly, the RNA interference-mediated silencing of cathepsin D stimulated ER expression but suppressed the level of HER2. The knockdown of cathepsin D enhanced the level of ZO-1 and a remarkable decrease in N-cadherin was also detected. Again, the matrix metalloproteinases (MMP) activity was impaired under the cathepsin D abolishment. Collectively, this study represented a modality to explore novel relationships in a proteome complex and highlighted the functional roles of cathepsin D in treatment options for different subtypes of breast cancer.

Tumor microenvironment and epithelial mesenchymal transition as targets to overcome tumor multidrug resistance

It is well established that multifactorial drug resistance hinders successful cancer treatment. Tumor cell interactions with the tumor microenvironment (TME) are crucial in epithelial-mesenchymal transition (EMT) and multidrug resistance (MDR). TME-induced factors secreted by cancer cells and cancer-associated fibroblasts (CAFs) create an inflammatory microenvironment by recruiting immune cells. CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) and inflammatory tumor associated macrophages (TAMs) are main immune cell types which further enhance chronic inflammation. Chronic inflammation nurtures tumor-initiating/cancer stem-like cells (CSCs), induces both EMT and MDR leading to tumor relapses. Pro-thrombotic microenvironment created by inflammatory cytokines and chemokines from TAMs, MDSCs and CAFs is also involved in EMT and MDR. MDSCs are the most common mediators of immunosuppression and are also involved in resistance to targeted therapies, e.g. BRAF inhibitors and oncolytic viruses-based therapies. Expansion of both cancer and stroma cells causes hypoxia by hypoxia-inducible transcription factors (e.g. HIF-1α) resulting in drug resistance. TME factors induce the expression of transcriptional EMT factors, MDR and metabolic adaptation of cancer cells. Promoters of several ATP-binding cassette (ABC) transporter genes contain binding sites for canonical EMT transcription factors, e.g. ZEB, TWIST and SNAIL. Changes in glycolysis, oxidative phosphorylation and autophagy during EMT also promote MDR. Conclusively, EMT signaling simultaneously increases MDR. Owing to the multifactorial nature of MDR, targeting one mechanism seems to be non-sufficient to overcome resistance. Targeting inflammatory processes by immune modulatory compounds such as mTOR inhibitors, demethylating agents, low-dosed histone deacetylase inhibitors may decrease MDR. Targeting EMT and metabolic adaptation by small molecular inhibitors might also reverse MDR. In this review, we summarize evidence for TME components as causative factors of EMT and anticancer drug resistance.

MicroRNA-based risk scoring system to identify early-stage oral squamous cell carcinoma patients at high-risk for cancer-specific mortality

Background

For early‐stage oral squamous cell carcinoma (OSCC), there is no existing risk‐stratification modality beyond conventional TNM staging system to identify patients at high risk for cancer‐specific mortality.

Methods

A total of 568 early‐stage OSCC patients who had surgery only and also with available 5‐year clinical outcomes data were identified. Signature microRNAs (miRNAs) were discovered using deep sequencing analysis and validated by qRT‐PCR. The final 5‐plex prognostic marker panel was utilized to generate a cancer‐specific mortality risk score using the multivariate Cox regression analyses. The prognostic markers were validated in the internal and external validation cohorts.

Results

The risk score from the 5‐plex marker panel consisting of miRNAs‐127‐3p, 4736, 655‐3p, TNM stage and histologic grading stratified patients into four risk categories. Compared to the low‐risk group, the high‐risk group had 23‐fold increased mortality risk (hazard ratio 23, 95% confidence interval 13‐42), with a median time‐to‐recurrence of 6 months and time‐to‐death of 11 months (vs >60 months for each among low‐risk patient; p < .001).

Conclusion

The miRNA‐based 5‐plex marker panel driven mortality risk score formula provides clinically practical and reliable measures to assess the prognosis of patients assigned to an early‐stage OSCC.

miR-190-5p in human diseases

miRNAs, a major class of small noncoding RNAs approximately 18-25 nucleotides in length, function by repressing the expression of target genes through binding to complementary sequences in the 3'-UTRs of target genes. Emerging evidence has highlighted their important roles in numerous diseases, including human cancers. Recently, miR-190 has been shown to be dysregulated in various types of human cancers that participates in cancer-related biological processes, including proliferation, apoptosis, metastasis, drug resistance, by regulating associated target genes, and to predict cancer diagnosis and prognosis. In this review, we summarized the roles of miR-190-5p in human diseases, especially in human cancers. Then we classified its target genes in tumorigenesis and progression, which might provide evidence for cancer diagnosis and prognosis, promising tools for cancer treatment, or leads for further investigation.