Functional Proteomics of Breast Cancer Metabolism Identifies GLUL as Responder during Hypoxic Adaptation.

Hypoxia as well as metabolism are central hallmarks of cancer, and hypoxia-inducible factors (HIFs) and metabolic effectors are crucial elements in oxygen-compromised tumor environments. Knowledge of changes in the expression of metabolic proteins in response to HIF function could provide mechanistic insights into adaptation to hypoxic stress, tumorigenesis, and disease progression. We analyzed time-resolved alterations in metabolism-associated protein levels in response to different oxygen potentials across breast cancer cell lines. Effects on the cellular metabolism of both HIF-dependent and -independent processes were analyzed by reverse-phase protein array profiling and a custom statistical model. We revealed a strong induction of glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA) as well as reduced glutamate-ammonia ligase (GLUL) protein levels across all cell lines tested as consistent changes upon hypoxia induction. Low GLUL protein levels were correlated with aggressive molecular subtypes in breast cancer patient data sets and also with hypoxic tumor regions in a xenograft mouse tumor model. Moreover, low GLUL expression was associated with poor survival in breast cancer patients and with high HIF-1α-expressing patient subgroups. Our data reveal time-resolved changes in the regulation of metabolic proteins under oxygen-deprived conditions and elucidate GLUL as a strong responder to HIFs and the hypoxic environment.

The highly expressed 5'isomiR of hsa-miR-140-3p contributes to the tumor-suppressive effects of miR-140 by reducing breast cancer proliferation and migration.

BACKGROUND: miRNAs are small noncoding RNA molecules that play an important role in post-transcriptional regulation of gene expression. Length and/or sequence variants of the same miRNA are termed isomiRs. While most isomiRs are functionally redundant compared to their canonical counterparts, the so-called 5'isomiRs exhibit a shifted 5' end and therefore a shifted seed sequence resulting in a different target spectrum. However, not much is known about the functional relevance of these isoforms. RESULTS: Analysis of miRNA-seq data from breast cancer cell lines identified six pairs of highly expressed miRNAs and associated 5'isomiRs. Among them, hsa-miR-140-3p was of particular interest because its 5'isomiR showed higher expression compared to the canonical miRNA annotated in miRbase. This miRNA has previously been shown to control stemness of breast cancer cells. miRNAseq data of breast cancer patients (TCGA dataset) showed that both the canonical hsa-miR-140-3p and its 5'isomiR-140-3p were highly expressed in patients' tumors compared to normal breast tissue. In the current work, we present the functional characterization of 5'isomiR-140-3p and the cellular phenotypes associated with its overexpression in MCF10A, MDA-MB-468 and MDA-MB-231 cell lines in comparison to the canonical hsa-miR-140-3p. Contrary to the effect of the canonical hsa-miR-140-3p, overexpression of the 5'isomiR-140-3p led to a decrease in cell viability. The latter observation was supported by cell cycle analysis, where the 5'isomiR-140-3p but not the hsa-miR-140-3p caused cell cycle arrest in G0/G1-phase. Additionally, 5'ismoiR-140-3p overexpression was found to cause a decrease in cell migration in the three cell lines. We identified three novel direct target genes of the 5'isomiR-140-3p; COL4A1, ITGA6 and MARCKSL1. Finally, we have shown that knocking down these genes partially phenocopied the effects of the 5'isomiR-140-4p overexpression, where COL4A1 and ITGA6 knockdown led to reduced cell viability and cell cycle arrest, while MARCKSL1 knockdown resulted in a decrease in the migratory potential of cells. CONCLUSIONS: In summary, this work presents evidence that there is functional synergy between the canonical hsa-miR-140-3p and the newly identified 5'isomiR-140-3p in suppressing growth and progression of breast cancer by simultaneously targeting genes related to differentiation, proliferation, and migration.

TGFß1 regulates HGF-induced cell migration and hepatocyte growth factor receptor MET expression via C-ets-1 and miR-128-3p in basal-like breast cancer.

Breast cancer is the most common cancer in women worldwide. The tumor microenvironment contributes to tumor progression by inducing cell dissemination from the primary tumor and metastasis. TGFß signaling is involved in breast cancer progression and is specifically elevated during metastatic transformation in aggressive breast cancer. In this study, we performed genomewide correlation analysis of TGFBR2 expression in a panel of 51 breast cancer cell lines and identified that MET is coregulated with TGFBR2. This correlation was confirmed at the protein level in breast cancer cell lines and human tumor tissues. Flow cytometric analysis of luminal and basal-like breast cancer cell lines and examination of 801 tumor specimens from a prospective cohort of breast cancer patients using reverse phase protein arrays revealed that expression of TGFBR2 and MET is increased in basal-like breast cancer cell lines, as well as in triple-negative breast cancer tumor tissues, compared to other subtypes. Using real-time cell analysis technology, we demonstrated that TGFß1 triggered hepatocyte growth factor (HGF)-induced and MET-dependent migration in vitro. Bioinformatic analysis predicted that TGFß1 induces expression of C-ets-1 as a candidate transcription factor regulating MET expression. Indeed, TGFß1-induced expression of ETS1 and breast cancer cell migration was blocked by knockdown of ETS1. Further, we identified that MET is a direct target of miR-128-3p and that this miRNA is negatively regulated by TGFß1. Overexpression of miR-128-3p reduced MET expression and abrogated HGF-induced cell migration of invasive breast cancer cells. In conclusion, we have identified that TGFß1 regulates HGF-induced and MET-mediated cell migration, through positive regulation of C-ets-1 and negative regulation of miR-128-3p expression in basal-like breast cancer cell lines and in triple-negative breast cancer tissue.

MicroRNA-519a-3p mediates apoptosis resistance in breast cancer cells and their escape from recognition by natural killer cells.

Aggressive breast cancer is associated with poor patient outcome and characterized by the development of tumor cell variants that are able to escape from control of the immune system or are resistant to targeted therapies. The complex molecular mechanisms leading to immune escape and therapy resistance are incompletely understood. We have previously shown that high miR-519a-3p levels are associated with poor survival in breast cancer. Here, we demonstrate that miR-519a-3p confers resistance to apoptosis induced by TRAIL, FasL and granzyme B/perforin by interfering with apoptosis signaling in breast cancer cells. MiR-519a-3p diminished the expression of its direct target genes for TRAIL-R2 (TNFRSF10B) and for caspase-8 (CASP8) and its indirect target gene for caspase-7 (CASP7), resulting in reduced sensitivity and tumor cell apoptosis in response to apoptotic stimuli. Furthermore, miR-519a-3p impaired tumor cell killing by natural killer (NK) cells via downregulation of the NKG2D ligands ULBP2 and MICA on the surface of tumor cells that are crucial for the recognition of these tumor cells by NK cells. We determined that miR-519a-3p was overexpressed in more aggressive mutant TP53 breast cancer that was associated with poor survival. Furthermore, low levels of TRAIL-R2, caspase-7 and caspase-8 correlated with poor survival, suggesting that the inhibitory effect of miR-519a-3p on TRAIL-R2 and caspases may have direct clinical relevance in lowering patient's prognosis. In conclusion, we demonstrate that miR-519a-3p is a critical factor in mediating resistance toward cancer cell apoptosis and impairing tumor cell recognition by NK cells. This joint regulation of apoptosis and immune cell recognition through miR-519a-3p supports the hypothesis that miRNAs are key regulators of cancer cell fate, facilitating cancer progression and evasion from immunosurveillance at multiple and interconnected levels.

miRNA-1246 induces pro-inflammatory responses in mesenchymal stem/stromal cells by regulating PKA and PP2A.

The tumor microenvironment (TME) has an impact on breast cancer progression by creating a pro-inflammatory milieu within the tumor. However, little is known about the roles of miRNAs in cells of the TME during this process. We identified six putative oncomiRs in a breast cancer dataset, all strongly correlating with poor overall patient survival. Out of the six candidates, miR-1246 was upregulated in aggressive breast cancer subtypes and expressed at highest levels in mesenchymal stem/stroma cells (MSCs). Functionally, miR-1246 led to a p65-dependent increase in transcription and release of pro-inflammatory mediators IL-6, CCL2 and CCL5 in MSCs, and increased NF-κB activity. The pro-inflammatory phenotype of miR-1246 in MSCs was independent of TNFα stimulations and mediated by direct targeting of the tumor-suppressors PRKAR1A and PPP2CB. In vitro recapitulation of the TME revealed increased Stat3 phosphorylation in breast epithelial (MCF10A) and cancer cells (SK-BR-3, MCF7, T47D) upon incubation with conditioned medium (CM) of MSCs overexpressing miR-1246. Additionally, this stimulation enhanced proliferation of MCF10A cells, increased migration of MDA-MB-231 cells and induced attraction of THP-1 monocytic cells. Our data shows that miR-1246 acts as both key-enhancer of pro-inflammatory responses in MSCs and putative oncomiR in breast cancer, suggesting its influence on cancer-related inflammation and breast cancer progression.

The quality of life of family caregivers of cancer patients in the east of Turkey.

PURPOSE: In this study, the aim was to examine the quality of life of family caregivers of cancer patients in the east of Turkey. METHOD: The study design was descriptive. Data were collected by the researcher in Oncology-Hematology policlinic and Chemotherapy unit of Yakutiye Research Hospital of Atatürk University. Participants were 18 years old and older. The sample included 106 family caregivers who were living in the same flat with the patients during caregiving. Data were collected using a questionnaire that included sociodemographic questions for family caregivers and the World Health Organization Quality of Life-Short Form, Turkish Version (WHOQOL-BREF TR). RESULTS: The mean domain scores of WHOQOL-BREF(TR) were 70.12 (SD=19.24) for social, 68.26 (SD=20.10) for physical, 59.70 (SD=18.07) for psychological, 56.32 (SD=15.12) for national environment, and 53.87 (SD=16.99) for environment domains. About 71.7% of caregivers shared the caregiving process with someone else. Environmental domain scores of those who shared the caregiving process with someone else were higher. The environment domain scores of men (49.6, SD=17.1) were lower than those of women. As the income lowers, lowered, so did the quality of life score in every domain. The quality of life scores of those feeling unhealthy during the last two weeks were low in every domain. CONCLUSION: Physical and psychological health of family caregivers in assisted living facilities should be comprehensively supported by professionals.