Interactions between RASA2, CADM1, HIF1AN gene polymorphisms and body fatness with breast cancer: a population-based case-control study in China

Organotypic 3D Cell-Architecture Impacts the Expression Pattern of miRNAs-mRNAs Network in Breast Cancer SKBR3 Cells

BACKGROUND

Currently, most of the research on breast cancer has been carried out in conventional two-dimensional (2D) cell cultures due to its practical benefits, however, the three-dimensional (3D) cell culture is becoming the model of choice in cancer research because it allows cell-cell and cell-extracellular matrix (ECM) interactions, mimicking the native microenvironment of tumors in vivo.

METHODS

In this work, we evaluated the effect of 3D cell organization on the expression pattern of miRNAs (by Small-RNAseq) and mRNAs (by microarrays) in the breast cancer SKBR3 cell line and analyzed the biological processes and signaling pathways regulated by the differentially expressed protein-coding genes (DE-mRNAs) and miRNAs (DE-microRNAs) found in the organoids.

RESULTS

We obtained well-defined cell-aggregated organoids with a grape cluster-like morphology with a size up to 9.2 × 105 μm3. The transcriptomic assays showed that cell growth in organoids significantly affected (all p < 0.01) the gene expression patterns of both miRNAs, and mRNAs, finding 20 upregulated and 19 downregulated DE-microRNAs, as well as 49 upregulated and 123 downregulated DE-mRNAs. In silico analysis showed that a subset of 11 upregulated DE-microRNAs target 70 downregulated DE-mRNAs. These genes are involved in 150 gene ontology (GO) biological processes such as regulation of cell morphogenesis, regulation of cell shape, regulation of canonical Wnt signaling pathway, morphogenesis of epithelium, regulation of cytoskeleton organization, as well as in the MAPK and AGE-RAGE signaling KEGG-pathways. Interestingly, hsa-mir-122-5p (Fold Change (FC) = 15.4), hsa-mir-369-3p (FC = 11.4), and hsa-mir-10b-5p (FC = 20.1) regulated up to 81% of the 70 downregulated DE-mRNAs.

CONCLUSION

The organotypic 3D cell-organization architecture of breast cancer SKBR3 cells impacts the expression pattern of the miRNAs-mRNAs network mainly through overexpression of hsa-mir-122-5p, hsa-mir-369-3p, and hsa-mir-10b-5p. All these findings suggest that the interaction between cell-cell and cell-ECM as well as the change in the culture architecture impacts gene expression, and, therefore, support the pertinence of migrating breast cancer research from conventional cultures to 3D models.

The Asparagine Hydroxylase FIH: A Unique Oxygen Sensor

Significance: Limited oxygen availability (hypoxia) commonly occurs in a range of physiological and pathophysiological conditions, including embryonic development, physical exercise, inflammation, and ischemia. It is thus vital for cells and tissues to monitor their local oxygen availability to be able to adjust in case the oxygen supply is decreased. The cellular oxygen sensor factor inhibiting hypoxia-inducible factor (FIH) is the only known asparagine hydroxylase with hypoxia sensitivity. FIH uniquely combines oxygen and peroxide sensitivity, serving as an oxygen and oxidant sensor. Recent Advances: FIH was first discovered in the hypoxia-inducible factor (HIF) pathway as a modulator of HIF transactivation activity. Several other FIH substrates have now been identified outside the HIF pathway. Moreover, FIH enzymatic activity is highly promiscuous and not limited to asparagine hydroxylation. This includes the FIH-mediated catalysis of an oxygen-dependent stable (likely covalent) bond formation between FIH and selected substrate proteins (called oxomers [oxygen-dependent stable protein oligomers]). Critical Issues: The (patho-)physiological function of FIH is only beginning to be understood and appears to be complex. Selective pharmacologic inhibition of FIH over other oxygen sensors is possible, opening new avenues for therapeutic targeting of hypoxia-associated diseases, increasing the interest in its (patho-)physiological relevance. Future Directions: The contribution of FIH enzymatic activity to disease development and progression should be analyzed in more detail, including the assessment of underlying molecular mechanisms and relevant FIH substrate proteins. Also, the molecular mechanism(s) involved in the physiological functions of FIH remain(s) to be determined. Furthermore, the therapeutic potential of recently developed FIH-selective pharmacologic inhibitors will need detailed assessment. Antioxid. Redox Signal. 37, 913-935.

AKT1 Transcriptomic Landscape in Breast Cancer Cells

Overexpression and hyperactivation of the serine/threonine protein kinase B (AKT) pathway is one of the most common cellular events in breast cancer progression. However, the nature of AKT1-specific genome-wide transcriptomic alterations in breast cancer cells and breast cancer remains unknown to this point. Here, we delineate the impact of selective AKT1 knock down using gene-specific siRNAs or inhibiting the AKT activity with a pan-AKT inhibitor VIII on the nature of transcriptomic changes in breast cancer cells using the genome-wide RNA-sequencing analysis. We found that changes in the cellular levels of AKT1 lead to changes in the levels of a set of differentially expressed genes and, in turn, imply resulting AKT1 cellular functions. In addition to an expected positive relationship between the status of AKT1 and co-expressed cellular genes, our study unexpectedly discovered an inherent role of AKT1 in inhibiting the expression of a subset of genes in both unstimulated and growth factor stimulated breast cancer cells. We found that depletion of AKT1 leads to upregulation of a subset of genes—many of which are also found to be downregulated in breast tumors with elevated high AKT1 as well as upregulated in breast tumors with no detectable AKT expression. Representative experimental validation studies in two breast cancer cell lines showed a reasonable concurrence between the expression data from the RNA-sequencing and qRT-PCR or data from ex vivo inhibition of AKT1 activity in cancer patient-derived cells. In brief, findings presented here provide a resource for further understanding of AKT1-dependent modulation of gene expression in breast cancer cells and broaden the scope and significance of AKT1 targets and their functions.

MicroRNA-155-3p promotes breast cancer progression through down-regulating CADM1

BACKGROUND/PURPOSE

Cell adhesion molecule 1 (CADM1) functions as a tumor suppressor and has been identified to be frequently inactivated in breast cancer, and closely associated with patients' poor prognosis and advanced TNM stage. However, the mechanisms underlying CADM1 in breast cancer progression remains incompletely clear. miR-155, a predicted modulator of CADM1 was reported to be overexpressed in breast cancer, and its high expression level was closely related to the malignant progression of breast cancer. The present study aimed to explore whether miR-155-3p could modulate CADM1 expression and then involved in the progression of breast cancer.

METHODS

The expression patterns of miR-155-3p in breast cancer tissues and cell lines were determined by RT-PCR technology. The relationship between CADM1 and miR-155-3p were determined by the luciferase gene reporter and Western Blot (WB) assays. Cell proliferation, apoptosis rates and tumorigenesis were determined by CCK-8, flow cytometry and in vivo xenotransplanation experiments, respectively.

RESULTS

miR-155-3p was up-regulated in breast cancer tissues and cells when compared to the adjacent normal tissues and normal breast MCF 10A cells. The mRNA and protein levels of CADM1 showed opposite expression patterns to that of miR-155-3p expression detected, and miR-155-3p could negatively regulate CADM1 expression in breast cancer MCF-7 cells. Moreover, gain-of function assay showed that overexpression of miR-155-3p promoted cell proliferation, tumorigenesis and repressed cell apoptosis, but these effects were all significantly impaired when the cells were simultaneously transfected with OE-CADM1, the overexpressing vector of CADM1.

CONCLUSION

This study revealed that miR-155-3p could accelerate the progression of breast cancer via down-regulation of CADM1 expression.

Polymorphisms in microRNA let-7 binding sites of the HIF1AN and CLDN12 genes can predict pathologic complete response to taxane- and platinum-based neoadjuvant chemotherapy in breast cancer

Background

Germline genetic polymorphisms in certain genes are associated with response to anthracycline- and taxane-based neoadjuvant chemotherapy in breast cancer (BC). Recent evidence has indicated that microRNA (miRNA) let-7 expression is associated with response to chemotherapeutics. This study aims to evaluate the potential role of let-7 miRNA-related single nucleotide polymorphisms (mirSNPs) in the prediction of pathologic complete response to taxane- and platinum-based neoadjuvant chemotherapy in locally advanced breast cancer (LABC).

Methods

We genotyped the SNPs that reside in and around miRNA let-7 binding sites of two target genes: hypoxia-inducible factor 1 subunit alpha inhibitor (HIF1AN) and claudin 12 (CLDN12). The distribution frequencies of the SNPs were genotyped in LABC patients who received taxane- and platinum-based neoadjuvant chemotherapy. Associations among tumour-relevant biomarkers, genotype and pathological complete response (pCR) were evaluated using Student's t-test for continuous variables and the chi-square or Fisher's exact tests for non-categorical variables. The modified odds ratios (ORs) with their 95% confidence intervals (CIs) were calculated by a multivariate logistic regression analysis to explore the association of genotype with pCR.

Results

For rs11292, which is located in the 3'-untranslated region (UTR) of HIF1AN, significant differences were detected in codominant, dominant and overdominant models between the patients who achieved pCR and those who did not (non-pCR) (P<0.05) in a multivariate analysis. For rs1017105, which is located in the 3'-UTR of CLDN12, significant differences were observed in the recessive model between the pCR and non-pCR patients with luminal-type BC.

Conclusions

Let-7-related mirSNPs could predict pathologic complete response to taxane- and platinum-based neoadjuvant chemotherapy in LABC, which suggests the potential role of variants of miRNA let-7-related gene networks as predictive markers in a clinical setting.