Adipocyte culture medium stimulates production of macrophage inhibitory cytokine 1 in MDA-MB-231 cells

Metformin ameliorates BMP2 induced adipocyte-like property in breast cancer cells

Neighboring adipocytes of tumor cells/cancer associated adipocytes supply many factors and fatty acids as fuel to cancer cells for inducing cancer progression and development. Epithelial breast cancer cells also differentiate into several cell types to meet various demands. This study reports that breast cancer cells exhibit inherent adipocyte-like property which is further enhanced in presence of BMP2. Antidiabetic metformin inhibits BMP2 induced adipocyte-like potential in breast cancer cells. Interestingly, breast cancer cells not only show lipid accumulation but also have ability to release lipid content. Thus, this study centers around the presence of the adipocyte cell-like property in breast cancer cells, the significance of BMP2 and metformin that may be explored in designing therapeutics against breast cancer.

Macrophage inhibitory cytokine-1 induced by a high-fat diet promotes prostate cancer progression by stimulating tumor-promoting cytokine production from tumor stromal cells

Background

Recent studies have indicated that a high‐fat diet (HFD) and/or HFD‐induced obesity may influence prostate cancer (PCa) progression, but the role of HFD in PCa microenvironment is unclear. This study aimed to delineate the molecular mechanisms of PCa progression under HFD milieus and define the stromal microenvironment focusing on macrophage inhibitory cytokine‐1 (MIC‐1) activation.

Methods

We investigated the effects of HFD on PCa stromal microenvironment and MIC‐1 signaling activation using PC‐3M‐luc‐C6 PCa model mice fed with HFD or control diet. Further, we explored the effect of periprostatic adipocytes derived from primary PCa patients on activation and cytokine secretion of prostate stromal fibroblasts. Expression patterns and roles of MIC‐1 signaling on human PCa stroma activation and progression were also investigated.

Results

HFD stimulated PCa cell growth and invasion as a result of upregulated MIC‐1 signaling and subsequently increased the secretion of interleukin (IL)‐8 and IL‐6 from prostate stromal fibroblasts in PC‐3M‐luc‐C6 PCa mouse model. In addition, periprostatic adipocytes directly stimulated MIC‐1 production from PC‐3 cells and IL‐8 secretion in prostate stromal fibroblasts through the upregulation of adipose lipolysis and free fatty acid release. The increased serum MIC‐1 was significantly correlated with human PCa stroma activation, high serum IL‐8, IL‐6, and lipase activity, advanced PCa progression, and high body mass index of the patients. Glial‐derived neurotrophic factor receptor α‐like (GFRAL), a specific receptor of MIC‐1, was highly expressed in both cytoplasm and membrane of PCa cells and surrounding stromal fibroblasts, and the expression level was decreased by androgen deprivation therapy and chemotherapy.

Conclusion

HFD‐mediated activation of the PCa stromal microenvironment through metabolically upregulated MIC‐1 signaling by increased available free fatty acids may be a critical mechanism of HFD and/or obesity‐induced PCa progression.

Stimulating effect of palmitate and insulin on cell migration and proliferation in PNT1A and PC3 prostate cells: Counteracting role of metformin

BACKGROUND

A potential association between obesity and prostate cancer has been proposed. Metformin, an antidiabetes drug, has antiproliferative effects being proposed for cancer treatment. However, under intense proliferative stimulation conditions such as those found in obesity, its efficacy is still uncertain. Thus, we analyzed the effects of saturated fatty acid and/or insulin under high concentrations, with or without metformin, on the proliferation and migration of prostate cells.

METHODS

Human prostate epithelial cell lines non-tumor (PNT1A) and tumor (PC3) were treated with control media (DMEM, C), palmitate (100 µM, HF), and/or insulin (50 µU, HI) with or without metformin (100 µM) for 24 or 48 h.

RESULTS

Both PNT1A and PC3 cells had greater proliferation when treated with HF, while HI treatment stimulated only PNT1A. Metformin inhibited cell proliferation caused by HF in both cell lines, but it did not block the proliferative action of HI in PNT1A cells. PNT1A increased cell migration after all treatments, while only HF influenced PC3; metformin inhibited the migration stimulated by all obese microenvironments. Both HF and HI treatments in PNT1A and HF treatment in PC3 augmented vimentin expression, resulting in a higher epithelial-mesenchymal transition (which, in turn, could influence cell migration). Metformin inhibited vimentin expression in both normal and tumor cells. Although HF treatment had increased AMPK activation, it also increased the levels of activated ERK1/2, which could be responsible for high cell proliferation in both cell lines. In contrast, HI decreased AMPK activation in both cell lines, whereas it increased ERK1/2 levels in PNT1A and decreased them in PC3 (reflecting greater cell proliferation only in non-tumor cells). Metformin maintained high activation of AMPK and decreased ERK1/2 levels after HF in both cell lines and only after HI in PNT1A, which was able to decrease the cell proliferation triggered by these treatments.

CONCLUSIONS

Higher concentrations of palmitate on PC3 cells and palmitate and insulin on PNT1A cells stimulate cellular activities that could favor cancer progression. Metformin inhibited most of these stimuli, showing the efficacy of this drug for cancer adjuvant therapy in obese patients (a group at increased risk for the development of prostrate cancer).

CRP Stimulates GDF15 Expression in Endothelial Cells through p53

Growth differentiation factor 15 (GDF15) is a multifunctional, secreted protein that is a direct target gene of p53. GDF15 is a prospective biomarker of cardiovascular disease (CVD). C-reactive protein (CRP), like GDF15, is implicated in inflammation and an independent biomarker of CVD. However, the molecular interactions between GDF15 and CRP remain unexplored. In women, we found a significant relationship between hsCRP and GDF15 serum and mRNA levels. In vitro treatment of cultured human aortic endothelial cells (HAECs) with purified CRP or transfection of a CRP plasmid into HAECs induced GDF15 expression. Dual-luciferase reporter assays confirmed that CRP significantly increased the levels of GDF15 promoter luciferase activity, indicating that CRP induces GDF15 transcription. Chromatin immunoprecipitation (ChIP) assays confirmed that p53 was recruited to both p53 binding sites 1 and 2 in the GDF15 promoter in response to CRP. We have uncovered a linkage between CRP and GDF15, a new clue that could be important in the pathogenesis of endothelial inflammation.

Human adipocytes stimulate invasion of breast cancer MCF-7 cells by secreting IGFBP-2

Background and Aims

A better understanding of the effects of human adipocytes on breast cancer cells may lead to the development of new treatment strategies. We explored the effects of adipocytes on the migration and invasion of breast cancer cells both in vitro and in vivo.

Methods

To study the reciprocal effects of adipocytes and cancer cells, we co-cultured human mature adipocytes and breast cancer cells in a system devoid of heterogeneous cell-cell contact. To analyze the factors that were secreted from adipocytes and that affected the invasive abilities of breast cancer cells, we detected different cytokines in various co-culture media. To study the communication of mature adipocytes and breast cancer cells in vivo, we chose 10 metastatic pathologic samples and 10 non-metastatic pathologic samples to do immunostaining.

Results

The co-culture media of human MCF-7 breast cancer cells and human mature adipocytes increased motility of MCF-7 cells. In addition, MMP-2 was remarkably up-regulated, whereas E-cadherin was down-regulated in these MCF-7 cells. Based on our co-culture medium chip results, we chose four candidate cytokines and tested their influence on metastasis individually. We found that IGFBP-2 enhanced the invasion ability of MCF-7 cells in vitro more prominently than did the other factors. In vivo, metastatic human breast tumors had higher levels of MMP-2 than did non-metastatic tumor tissue, whereas adipocytes around metastatic breast tumors had higher levels of IGFBP-2 than did adipocytes surrounding non-metastatic breast tumors.

Conclusions

IGFBP-2 secreted by mature adipocytes plays a key role in promoting the metastatic ability of MCF-7 breast cancer cells.

Gene expression differences in adipose tissue associated with breast tumorigenesis

Long thought to function only as an inert energy storage depot, the role of adipose tissue in breast tumorigenesis has been largely ignored. In light of increasing rates of obesity and use of breast conserving therapy and autologous fat grafting, improved understanding of the role of adipose tissue in tumor etiology is crucial. Thus, adipose tissue adjacent to and distant from invasive breast tumors (n = 20), or adjacent to non-malignant diagnoses (n = 20) was laser microdissected from post-menopausal women. Gene expression data were generated using microarrays and data analyzed to identify significant patterns of differential expression between adipose tissue groups at the individual gene and molecular pathway level. Pathway analysis revealed significant differences in immune response between non-malignant, distant, and tumor-adjacent adipose tissue, with the highest response in tumor-adjacent and lowest in non-malignant adipose tissue. Adipose tissue from invasive breasts exhibits increased expression of anti-inflammatory genes such as MARCO and VSIG4 while genes differentially expressed between tumor-adjacent and distant adipose tissue such as SPP1, RRM2, and MMP9, are associated with increased cellular proliferation, invasion, and angiogenesis. These data suggest that molecular profiles of adipose tissue differ depending on presence of or proximity to tumor cells. Heightened immunotolerance in adipose tissue from invasive breasts provides a microenvironment favorable to tumorigenesis. In addition, tumor-adjacent adipose tissue demonstrates expression of genes associated with tumor growth and progression. Thus, adipose tissue is not an inert component of the breast microenvironment but plays an active role in tumorigenesis.

Diet-induced macrophage inhibitory cytokine 1 promotes prostate cancer progression

Recent studies have indicated that a high-fat diet (HFD) plays an important role in prostate cancer (PCa) progression. Palmitic acid (PA) is one of the most abundant saturated free fatty acids (FAs) and is associated with carcinogenesis. In this study, we investigated the mechanism underlying the association of dietary fat, including PA, with PCa progression. In four PCa cell lines, in vitro PA administration stimulated the expression of macrophage inhibitory cytokine 1 (MIC1), which is a divergent member of the transforming growth factor-β family. In vivo, LNCaP xenograft tumor growth, serum MIC1 levels, and FA levels in xenograft tumors were significantly higher in mice receiving an HFD containing high amounts of PA than in those receiving a low-fat diet (LFD). In addition, tumor cells with high MIC1 expression invaded to venules and lymph vessels in the LNCaP xenograft. In vitro studies showed that proliferation and invasive capacity were significantly higher in PCa cells cultured with serum from HFD-fed mice than in those cultured with the serum from LFD-fed mice. This effect was attenuated by the addition of neutralizing antibodies against MIC1, but not by isotype control antibodies. Clinically, serum MIC1 levels were significantly higher in PCa patients than in healthy controls, and higher levels were associated with higher pathological grade and obesity. In conclusion, our results indicate that an HFD containing PA may promote growth and invasiveness of PCa cells through the upregulation of MIC1 expression.

BMP9 inhibits the bone metastasis of breast cancer cells by downregulating CCN2 (connective tissue growth factor, CTGF) expression

Bone morphogenetic proteins (BMPs), which belong to the transforming growth factor-β superfamily, regulate a wide range of cellular responses including cell proliferation, differentiation, adhesion, migration, and apoptosis. BMP9, the latest BMP to be discovered, is reportedly expressed in a variety of human carcinoma cell lines, but the role of BMP9 in breast cancer has not been fully clarified. In a previous study, BMP9 was found to inhibit the growth, migration, and invasiveness of MDA-MB-231 breast cancer cells. In the current study, the effect of BMP9 on the bone metastasis of breast cancer cells was investigated. After absent or low expression of BMP9 was detected in the MDA-MB-231 breast cancer cells and breast non-tumor adjacent tissues using Western blot and immunohistochemistry, In our previous study, BMP9 could inhibit the proliferation and invasiveness of breast cancer cells MDA-MB-231 in vitro and in vivo. This paper shows that BMP9 inhibit the bone metastasis of breast cancer cells by activating the BMP/Smad signaling pathway and downregulating connective tissue growth factor (CTGF); however, when CTGF expression was maintained, the inhibitory effect of BMP9 on the MDA-MB-231 cells was abolished. Together, these observations indicate that BMP9 is an important mediator of breast cancer bone metastasis and a potential therapeutic target for treating this deadly disease.

Adipose tissue and breast epithelial cells: a dangerous dynamic duo in breast cancer

Among the many different cell types surrounding breast cancer cells, the most abundant are those that compose mammary adipose tissue, mainly mature adipocytes and progenitors. New accumulating recent evidences bring the tumor-surrounding adipose tissue into the light as a key component of breast cancer progression. The purpose of this review is to emphasize the role that adipose tissue might play by locally affecting breast cancer cell behavior and subsequent clinical consequences arising from this dialog. Two particular clinical aspects are addressed: obesity that was identified as an independent negative prognostic factor in breast cancer and the oncological safety of autologous fat transfer used in reconstructive surgery for breast cancer patients. This is preceded by the overall description of adipose tissue composition and function with special emphasis on the specificity of adipose depots and the species differences, key experimental aspects that need to be taken in account when cancer is considered.

The H6D variant of NAG-1/GDF15 inhibits prostate xenograft growth in vivo

BACKGROUND

Non-steroidal anti-inflammatory drug-activated gene (NAG-1), a divergent member of the transforming growth factor-beta superfamily, has been implicated in many cellular processes, including inflammation, early bone formation, apoptosis, and tumorigenesis. Recent clinical studies suggests that a C to G single nucleotide polymorphism at position 6 (histidine to aspartic acid substitution, or H6D) of the NAG-1 protein is associated with lower human prostate cancer incidence. The objective of the current study is to investigate the activity of NAG-1 H6D variant in prostate cancer tumorigenesis in vivo.

METHODS

Human prostate cancer DU145 cells expressing the H6D NAG-1 or wild-type (WT) NAG-1 were injected subcutaneously into nude mice and tumor growth was monitored. Serum and tumor samples were collected for subsequent analysis.

RESULTS

The H6D variant was more potent than the WT NAG-1 and inhibited tumor growth significantly compared to control mice. Mice with tumors expressing the WT NAG-1 have greater reduced both body weight and abdominal fat than mice with H6D variant tumors suggesting different activities of the WT NAG-1 and the H6D NAG-1. A significant reduction in adiponectin, leptin, and IGF-1 serum levels was observed in the tumor-bearing mice with a more profound reduction observed with expression of H6D variant. Cyclin D1 expression was suppressed in the tumors with a dramatic reduction observed in the tumor expressing the H6D variant.

CONCLUSION

Our data suggest that the H6D variant of NAG-1 inhibits prostate tumorigenesis by suppressing IGF-1 and cyclin D1 expression but likely additional mechanisms are operative.

Growth/differentiation factor-15: prostate cancer suppressor or promoter?

Deregulation of expression and function of cytokines belonging to the transforming growth factor-β (TGF-β) family is often associated with various pathologies. For example, this cytokine family has been considered a promising target for cancer therapy. However, the detailed functions of several cytokines from the TGF-β family that could have a role in cancer progression and therapy remain unclear. One of these molecules is growth/differentiation factor-15 (GDF-15), a divergent member of the TGF-β family. This stress-induced cytokine has been proposed to possess immunomodulatory functions and its high expression is often associated with cancer progression, including prostate cancer (PCa). However, studies clearly demonstrating the mechanisms for signal transduction and functions in cell interaction, cancer progression and therapy are still lacking. New GDF-15 roles have recently been identified for modulating osteoclast differentiation and for therapy for PCa bone metastases. Moreover, GDF-15 is as an abundant cytokine in seminal plasma with immunosuppressive properties. We discuss studies that focus on the regulation of GDF-15 expression and its role in tissue homeostasis, repair and the immune response with an emphasis on the role in PCa development.

Cancer secretomics reveal pathophysiological pathways in cancer molecular oncology

Emerging proteomic tools and mass spectrometry play pivotal roles in protein identification, quantification and characterization, even in complex biological samples. The cancer secretome, namely the whole collection of proteins secreted by cancer cells through various secretory pathways, has only recently been shown to have significant potential for diverse applications in oncoproteomics. For example, secreted proteins might represent putative tumor biomarkers or therapeutic targets for various types of cancer. Consequently, many proteomic strategies for secretome analysis have been extensively deployed over the last few years. These efforts generated a large amount of information awaiting deeper mining, better understanding and careful interpretation. Distinct sub-fields, such as degradomics, exosome proteomics and tumor-host cell interactions have been developed, in an attempt to provide certain answers to partially elucidated mechanisms of cancer pathobiology. In this review, advances, concerns and challenges in the field of secretome analysis as well as possible clinical applications are discussed.

Growth differentiation factor-15: a new biomarker in cardiovascular disease

Growth differentiation factor-(GDF-)15 is a stress-responsive cytokine that is emerging as a biomarker of cardiac and vascular dysfunction and disease. Elevated circulating levels of GDF-15 identify high-risk individuals across the cardiovascular continuum, from stable coronary artery disease to acute coronary syndrome and heart failure. The association of GDF-15 with outcome in these conditions is independent of clinical risk factors and established biomarkers, including NT-proBNP (N-terminal pro-B-type natriuretic peptide) and troponin. The prognostic information provided by GDF-15 in cardiovascular disease may inform patient management, e.g., by identifying patients with non-ST segment elevation acute coronary syndrome who benefit from an invasive strategy, or by monitoring treatment response in heart failure. Future studies need to evaluate prospectively whether GDF-15, alone or as part of a multimarker strategy, can improve contemporary risk prediction algorithms and support therapeutic management of patients with cardiovascular disease.

Growth-differentiation factor-15 in heart failure

The stress-responsive transforming growth factor-beta-related cytokine, growth-differentiation factor-15 (GDF-15), is emerging as a new biomarker in patients with cardiovascular disease. The circulating levels of GDF-15 are elevated and independently related to an adverse prognosis in acute coronary syndrome and left- or right-sided heart failure. GDF-15 adds significant prognostic information to established clinical and biochemical risk markers in these conditions. Elevated levels of GDF-15 may identify patients who have non-ST-elevation acute coronary syndrome who derive the greatest benefit from an invasive treatment strategy. As with other heart failure biomarkers, including BNP, it is currently not known what specific therapies could be used to reduce the risk associated with elevated levels of GDF-15 in heart failure. Further elucidation of the pathobiology and upstream inducers of this new biomarker may lead to new therapeutic concepts that address the risk associated with elevated GDF-15 levels. A commercial assay for GDF-15 should be available in the near future.

Growth-differentiation factor-15 is an independent marker of cardiovascular dysfunction and disease in the elderly: results from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) Study

AIMS

Growth-differentiation factor-15 (GDF-15) is emerging as an independent prognostic biomarker in patients with cardiovascular (CV) disease. Little is known about the pathophysiological basis for the close association of GDF-15 to future CV events. We hypothesized that GDF-15 is related to underlying CV pathologies.

METHODS AND RESULTS

To relate the levels of GDF-15 to indices of CV dysfunction and disease in elderly individuals, serum levels of GDF-15 were measured in 1004 subjects aged 70 years from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Carotid intima-media thickness and plaque burden, and left ventricular (LV) geometry and function were assessed by ultrasound. Endothelial function was evaluated in forearm resistance vessels and in the brachial artery by venous occlusion plethysmography and ultrasound imaging, respectively. Elevated levels of GDF-15 were related to several CV risk factors (male gender, current smoking, body mass index, waist circumference, diabetes, fasting glucose, triglycerides, and low HDL cholesterol). After adjustment for CV risk factors, increased levels of GDF-15 were associated with reduced endothelium-dependent vasodilation in resistance vessels, plaque burden, LV mass and concentric LV hypertrophy, reduced LV ejection fraction, and clinical manifestations of coronary artery disease and heart failure.

CONCLUSION

GDF-15 carries information on CV dysfunction and disease that is not captured by traditional CV risk factors in elderly individuals.