The effects of diet induced obesity on breast cancer associated pathways in mice deficient in SFRP1

Secreted Frizzled Related Proteins in Cardiovascular and Metabolic Diseases

Abnormal gene expression and secreted protein levels are accompanied by extensive pathological changes. Secreted frizzled related protein (SFRP) family members are antagonistic inhibitors of the Wnt signaling pathway, and they were recently found to be involved in the pathogenesis of a variety of metabolic diseases, which has led to extensive interest in SFRPs. Previous reports highlighted the importance of SFRPs in lipid metabolism, obesity, type 2 diabetes mellitus and cardiovascular diseases. In this review, we provide a detailed introduction of SFRPs, including their structural characteristics, receptors, inhibitors, signaling pathways and metabolic disease impacts. In addition to summarizing the pathologies and potential molecular mechanisms associated with SFRPs, this review further suggests the potential future use of SFRPs as disease biomarkers therapeutic targets.

Modeling of the immune response in the pathogenesis of solid tumors and its prognostic significance

BACKGROUND

Tumor initiation and subsequent progression are usually long-term processes, spread over time and conditioned by diverse aspects. Many cancers develop on the basis of chronic inflammation; however, despite dozens of years of research, little is known about the factors triggering neoplastic transformation under these conditions. Molecular characterization of both pathogenetic states, i.e., similarities and differences between chronic inflammation and cancer, is also poorly defined. The secretory activity of tumor cells may change the immunophenotype of immune cells and modify the extracellular microenvironment, which allows the bypass of host defense mechanisms and seems to have diagnostic and prognostic value. The phenomenon of immunosuppression is also present during chronic inflammation, and the development of cancer, due to its duration, predisposes patients to the promotion of chronic inflammation. The aim of our work was to discuss the above issues based on the latest scientific insights. A theoretical mechanism of cancer immunosuppression is also proposed.

CONCLUSIONS

Development of solid tumors may occur both during acute and chronic phases of inflammation. Differences in the regulation of immune responses between precancerous states and the cancers resulting from them emphasize the importance of immunosuppressive factors in oncogenesis. Cancer cells may, through their secretory activity and extracellular transport mechanisms, enhance deterioration of the immune system which, in turn, may have prognostic implications.

Role of Secreted Frizzled-Related Protein 1 in Early Mammary Gland Tumorigenesis and Its Regulation in Breast Microenvironment

In mice, the lack of secreted frizzled-related protein 1 (SFRP1) is responsible for mammogenesis and hyperplasia, while, in bovines, its overexpression is associated with post-lactational mammary gland involution. Interestingly, there are no reports dealing with the role of SFRP1 in female involution. However, SFRP1 dysregulation is largely associated with human tumorigenesis in the literature. Indeed, the lack of SFRP1 is associated with both tumor development and patient prognosis. Considering the increased risk of breast tumor development associated with incomplete mammary gland involution, it is crucial to demystify the "grey zone" between physiological age-related involution and tumorigenesis. In this review, we explore the functions of SFRP1 involved in the breast involution processes to understand the perturbations driven by the disappearance of SFRP1 in mammary tissue. Moreover, we question the presence of recurrent microcalcifications identified by mammography. In bone metastases from prostate primary tumor, overexpression of SFRP1 results in an osteolytic response of the tumor cells. Hence, we explore the hypothesis of an osteoblastic differentiation of mammary cells induced by the lack of SFRP1 during lobular involution, resulting in a new accumulation of hydroxyapatite crystals in the breast tissue.

Functional transcriptomic annotation and protein-protein interaction network analysis identify NEK2, BIRC5, and TOP2A as potential targets in obese patients with luminal A breast cancer

PURPOSE

Although obesity is a risk factor for breast cancer, little effort has been made in the identification of druggable molecular alterations in obese-breast cancer patients. Tumors are controlled by their surrounding microenvironment, in which the adipose tissue is a main component. In this work, we intended to describe molecular alterations at a transcriptomic and protein-protein interaction (PPI) level between obese and non-obese patients.

METHODS AND RESULTS

Gene expression data of 269 primary breast tumors were compared between normal-weight (BMI < 25, n = 130) and obese (IMC > 30, n = 139) patients. No significant differences were found for the global breast cancer population. However, within the luminal A subtype, upregulation of 81 genes was observed in the obese group (FC ≥ 1.4). Next, we explored the association of these genes with patient outcome, observing that 39 were linked with detrimental outcome. Their PPI map formed highly compact cluster and functional annotation analyses showed that cell cycle, cell proliferation, cell differentiation, and cellular response to extracellular stimuli were the more altered functions. Combined analyses of genes within the described functions are correlated with poor outcome. PPI network analyses for each function were to search for druggable opportunities. We identified 16 potentially druggable candidates. Among them, NEK2, BIRC5, and TOP2A were also found to be amplified in breast cancer, suggesting that they could act as strategic players in the obese-deregulated transcriptome.

CONCLUSION

In summary, our in silico analysis describes molecular alterations of luminal A tumors and proposes a druggable PPI network in obese patients with potential for translation to the clinical practice.

Analysis of the miRNA-mRNA-lncRNA network in human estrogen receptor-positive and estrogen receptor-negative breast cancer based on TCGA data

Estrogen receptor-positive (ER⁺) and ER-negative (ER^-) subtypes of breast cancer have distinct clinical outcomes because they respond differentially to endocrine therapies. We aimed to comprehensively analyze differentially expressed microRNA (miRNAs), long non-coding RNAs (lncRNAs) and mRNAs in different ER subtypes as well as to identify prognosis-related RNAs. The expression levels of miRNAs, lncRNAs, and mRNAs between breast cancer and normal samples were compared using data from The Cancer Genome Atlas database. Differentially expressed miRNAs, lncRNAs and mRNAs between ER⁺ and ER^- samples were also screened. An ER subtype-related miRNA-lncRNA-mRNA network was constructed. lncRNAs and mRNAs in this network were further subjected to an analysis of their associations with patient prognosis. Sets of differentially expressed miRNAs, lncRNAs, and miRNAs between breast cancer and normal samples were identified among which 14 miRNAs, 78 lncRNAs, and 475 mRNAs were differentially expressed between ER subtypes. Relationships between these RNAs were analyzed. The resultant ER subtype-related miRNA-lncRNA-mRNA network consisted of 14 nodes, among which LINC0092 and chromosome 2 open reading frame 71 (C2orf71) were correlated with better prognosis of breast cancer. LINC0092 was co-expressed with SFRP1 and RGMA and regulated by hsa-miR-449a and hsa-miR-452-5p. C2orf71 was co-expressed with LINC00511 and regulated by hsa-miR-184. Cross-talk among differentially expressed miRNAs, lncRNAs, and miRNAs may be an important feature in ER⁺ and ER^- subtypes of breast cancer. LINC0092 and C2orf71, two of these cross-talking RNAs, may serve as novel prognostic predictor of breast cancer because of their close associations with prognosis.

Obesity and Diabetes: The Increased Risk of Cancer and Cancer-Related Mortality

Obesity and type 2 diabetes are becoming increasingly prevalent worldwide, and both are associated with an increased incidence and mortality from many cancers. The metabolic abnormalities associated with type 2 diabetes develop many years before the onset of diabetes and, therefore, may be contributing to cancer risk before individuals are aware that they are at risk. Multiple factors potentially contribute to the progression of cancer in obesity and type 2 diabetes, including hyperinsulinemia and insulin-like growth factor I, hyperglycemia, dyslipidemia, adipokines and cytokines, and the gut microbiome. These metabolic changes may contribute directly or indirectly to cancer progression. Intentional weight loss may protect against cancer development, and therapies for diabetes may prove to be effective adjuvant agents in reducing cancer progression. In this review we discuss the current epidemiology, basic science, and clinical data that link obesity, diabetes, and cancer and how treating obesity and type 2 diabetes could also reduce cancer risk and improve outcomes.

Estrogen-mediated signaling is differentially affected by the expression levels of Sfrp1 in mammary epithelial cells

Estrogen has been implicated in breast cancer risk for a variety of reasons including its role in stimulating mammary cell division. Secreted frizzled-related proteins (SFRPs) are a family of Wnt signaling antagonists. Loss of Sfrp1 in mice results in focal ductal epithelial hyperplasias and in humans, loss of SFRP1 is associated with early changes in premalignant breast lesions as well as poor overall survival in patients with early stage breast cancer. Considering that SFRP1 expression is further reduced in ER positive breast cancers when compared with ER negative breast cancers, we chose to determine whether loss of Sfrp1 alters ER signaling. Immunohistochemical analysis revealed that loss of Sfrp1 significantly increased the number of PR and BrdU positve cells in the mammary gland. We further demonstrate that down stream actions of ER-mediated signaling, including cellular proliferation and PR transcription, are elevated in estradiol treated explant cultures derived from Sfrp1(-/-) mice. Additionally, we show that Control explant cultures treated with estradiol exhibit an increase in the mRNA levels of Sfrp1. Finally, we establish that in human mammary epithelial cells with either SFRP1 knocked down (TERT-siSFRP1) and rescued SFRP1 expression (MCF7-SFRP1), estrogen signaling is augmented. Modulation of ER activity appears to be through a mechanism dependent upon Wnt/β-catenin activity. Taken together, our data suggest an important control mechanism by which estrogen signaling is tempered in normal cells and indicates why loss of SFRP1 in early lesions might be a causal change leading to enhanced estrogen-mediated proliferation.