Human renal adipose tissue from normal and tumor kidney: its influence on renal cell carcinoma

FABP4-mediated ERK phosphorylation promotes renal cancer cell migration

Clear cell Carcinoma (ccRCC) is the most common and lethal subtype among renal cancers. In the present study we investigated the potential role of fatty acid-binding protein 4 (FABP4), also known as adipocyte FABP (A-FABP) or aP2 on ccRCC progression. Firstly, we found that FABP4 median serum levels were significantly higher in ccRCC patients compared to HD. Based on this result and to evaluate whether FABP4 plays a role on renal cancer malignant phenotype, we analyzed proliferation and migration in 786-O and ACHN cell lines using recombinant FABP4. We found that FABP4 significantly increased cell migration, whereas it had no significant effect on proliferation. As FABP4 is mainly expressed by adipocytes, we measured FABP4 adipocyte conditioned media (Ad-CM) levels showing that Ad-CM from ccRCC (Ad-CM ccRCC) had significantly higher mean values compared to Ad-CM obtained from Healthy Donors (HD). To assess the effects of adipocyte-released FABP-4, on cancer malignant phenotype we evaluated 786-O and ACHN proliferation and migration, using Ad-CM from ccRCC and Ad-CM from HD alone or in combination with FABP4 inhibitor BMS309403. Our results showed that Ad-CM enhanced cell proliferation in ACHN, but not in 786-O and on cell motility in both cell lines and this effect was partially reverted by BMS309403 in both cell lines. Moreover, in both cell lines, FABP4 effect was associated with an increased ERK phosphorylation. Collectively these data support the role of FABP4 in ccRCC progression and its potential use as noninvasive biomarker and therapeutic target for ccRCC.

Obesity alters the fitness of peritumoral adipose tissue, exacerbating tumor invasiveness in renal cancer through the induction of ADAM12 and CYP1B1

Obesity exacerbates the risk and aggressiveness of many types of cancer. Adipose tissue (AT) represents a prevalent component of the tumor microenvironment (TME) and contributes to cancer development and progression. Reciprocal communication between cancer and adipose cells leads to the generation of cancer-associated adipocytes (CAAs), which in turn foster tumor invasiveness by producing paracrine metabolites, adipocytokines, and growth factors. Interfering with the crosstalk between CAAs and cancer cells is of key relevance in the prevention of tumor progression. The present study aimed to analyze the contribution of peritumoral AT in renal cell carcinoma (RCC) progression in lean versus overweight or obese patients. By isolating human adipose-derived stromal/stem cells from the three groups of patients and performing conditioned medium studies with RCC cells along with in vivo xenograft experiments, we found that peritumoral adipocytes from the three groups show a distinct expression profile of genes. In particular, ADAM metallopeptidase domain 12 (ADAM12) and cytochrome P450 family 1 subfamily B member 1 (CYP1B1) were found to be upregulated in obesity and their silencing reduced RCC cell invasiveness. In conclusion, high ADAM12 and CYP1B1 expressions in the peritumoral adipocytes boost tumor invasiveness and may serve as an indicator of poor prognosis in RCC.

The prognostic role of perirenal fat tissue in non-metastatic renal cell carcinoma

PURPOSE

The aim of this study was to evaluate the impact of perirenal fat volume and perirenal fat density on prognosis in surgically treated non-metastatic renal cell carcinomas (RCC).

METHODS AND MATERIALS

All consecutive patients who underwent partial or total nephrectomy surgery between March 2019 and December 2021 were assessed. Measurements of perirenal fat volume and perirenal fat density were performed on computed tomography (CT) images. The relationship between progression and perirenal fat parameters was evaluated using ROC analysis, Cox regression analysis, and Kaplan-Meier analysis.

RESULTS

In the study population comprising 118 patients diagnosed with RCC (74.6% male, mean age of 59.1 ± 11.8 years), the median follow-up duration was 43 months (interquartile range: 33-51 months). Perirenal fat volume (AUC: 0.669, 95% CI 0.538-0.799, p = 0.011) and perirenal fat density (AUC: 0.680, 95% CI 0.558-0.803, p = 0.007) demonstrated acceptable discrimination performance in predicting progression. There was a significant association between high perirenal fat volume and high perirenal fat density with poor progression-free survival (HR: 1.007, 95% CI 1.003-1.011, p = 0.001 vs. HR: 1.084, 95% CI 1.033-1.137, p = 0.001; respectively).

CONCLUSION

High perirenal fat volume and high perirenal fat density are independent predictors for poor progression-free survival. Perirenal fat parameters, easily obtainable from preoperative CT images, may serve as potential tools in predicting the prognosis of non-metastatic RCC.

Causal Association of Adipose Tissue with Bladder Cancer and the Mediating Effects of Circulating Metabolites: A Mendelian Randomization Study

Background: Previous studies have indicated that there is an association between obesity and bladder cancer (BCa). However, the relationship between fat distribution, which is more representative of the risk of obesity, and BCa remains unclear. This study aimed to investigate the causal relationship between fat distribution and BCa, and the mediating role of circulating metabolites. Methods: The necessary data were obtained from a large Genome-Wide Association Studies (GWAS) database. Two-sample and two-step Mendelian randomization (MR) analyses were performed to investigate the association between fat distribution and BCa, as well as the mediating effect of circulating metabolites. The inverse variance weighted (IVW) method was the main analysis method. Heterogeneity tests, horizontal pleiotropy analyses, Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) tests, and leave-one-out analyses were performed to assess the stability of the results. Results: The IVW method indicated that abdominal subcutaneous adipose tissue adjusted for body mass index (BMI) and height (ASATadj) and abdominal subcutaneous/gluteofemoral adipose tissue (ASAT/GFAT) increased the risk of BCa. The odds ratio (OR) for ASATadj was 1.78 (95% CI=1.27-2.50, p=0.001) and that for ASAT/GFAT was 1.64 (95% CI=1.01-2.66, p=0.047). Furthermore, two-step MR analysis revealed that the effect of ASAT/GFAT on BCa was mediated by valine (proportion mediated: 7.13%, 95% CI = 3.57%-10.69%, p=0.045). Conclusions: Our research shows that, unlike most studies which focus on visceral fat, ASAT also impacts human health by increasing the risk of BCa, with the blood metabolite valine involved in this process. Monitoring and reducing ASAT accumulation can help reducce the disease burden of BCa.

Update on Adipose Tissue and Cancer

Adipose tissue is the largest endocrine organ and an accepted contributor to overall energy homeostasis. There is strong evidence linking increased adiposity to the development of 13 types of cancer. With increased adiposity comes metabolic dysfunction and insulin resistance, and increased systemic insulin and glucose support the growth of many cancers, including those of the colon and endometrium. There is also an important direct crosstalk between adipose tissue and various organs. For instance, the healthy development and function of the mammary gland, as well as the development, growth, and progression of breast cancer, are heavily impacted by the breast adipose tissue in which breast epithelial cells are embedded. Cells of the adipose tissue are responsive to external stimuli, including overfeeding, leading to remodeling and important changes in the secretion of factors known to drive the development and growth of cancers. Loss of factors like adiponectin and increased production of leptin, endotrophin, steroid hormones, and inflammatory mediators have been determined to be important mediators of the obesity-cancer link. Obesity is also associated with a structural remodeling of the adipose tissue, including increased localized fibrosis and disrupted angiogenesis that contribute to the development and progression of cancers. Furthermore, tumor cells feed off the adipose tissue, where increased lipolysis within adipocytes leads to the release of fatty acids and stromal cell aerobic glycolysis leading to the increased production of lactate. Both have been hypothesized to support the higher energetic demands of cancer cells. Here, we aim to provide an update on the state of the literature revolving around the role of the adipose tissue in cancer initiation and progression.

Cellular and Molecular Players in the Tumor Microenvironment of Renal Cell Carcinoma

Globally, clear-cell renal cell carcinoma (ccRCC) represents the most prevalent type of kidney cancer. Surgery plays a key role in the treatment of this cancer, although one third of patients are diagnosed with metastatic ccRCC and about 25% of patients will develop a recurrence after nephrectomy with curative intent. Molecular-target-based agents, such as tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs), are recommended for advanced cancers. In addition to cancer cells, the tumor microenvironment (TME) includes non-malignant cell types embedded in an altered extracellular matrix (ECM). The evidence confirms that interactions among cancer cells and TME elements exist and are thought to play crucial roles in the development of cancer, making them promising therapeutic targets. In the TME, an unfavorable pH, waste product accumulation, and competition for nutrients between cancer and immune cells may be regarded as further possible mechanisms of immune escape. To enhance immunotherapies and reduce resistance, it is crucial first to understand how the immune cells work and interact with cancer and other cancer-associated cells in such a complex tumor microenvironment.

A hint for the obesity paradox and the link between obesity, perirenal adipose tissue and Renal Cell Carcinoma progression

Increasing evidence supports a role for local fat depots in cancer outcomes. Despite the robust positive association of obesity with renal cell carcinoma (RCCa) diagnosis, increased adiposity is inversely related to RCCa oncological outcomes. Here, we sought to ascertain whether imagiologically assessed local fat depots associate with RCCa progression and survival and account for this apparent paradox. A retrospective cohort of renal carcinoma patients elective for nephrectomy (n = 137) were included. Beyond baseline clinicopathological characteristics, computed tomography (CT)-scans at the level of renal hilum evaluated areas and densities of different adipose tissue depots (perirenal, subcutaneous, visceral) and skeletal muscle (erector spinae, psoas and quadratus lumborum muscles) were analyzed. Univariate and multivariable Cox proportional hazards models were estimated following empirical analysis using stepwise Cox regression. Age, visceral adipose tissue (VAT) area and body mass index (BMI) predicted tumour-sided perirenal fat area (R² = 0.584), which presented upregulated UCP1 expression by 27-fold (P = 0.026) and smaller adipocyte areas, compared with subcutaneous depot. Multivariate analyses revealed that increased area of perirenal adipose tissue (PRAT) on the contralateral and tumour side associate with improved progression-free survival (HR = 0.3, 95CI = 0.1-0.8, P = 0.019) and overall survival (HR = 0.3, 95CI = 0.1-0.7, P = 0.009). PRAT measurements using CT, might become a possible tool, well correlated with other measures of obesity such as VAT and BMI, that will improve determination of obesity and contribute to assess the risk for disease progression and mortality in renal cancer patients. Present data supports the obesity paradox in RCCa, assumed that larger PRAT areas seem to protect from disease progression and death.

Renal peritumoral adipose tissue undergoes a browning process and stimulates the expression of epithelial-mesenchymal transition markers in human renal cells

Tumor cells can interact with neighboring adipose cells and adipocyte dedifferentiation appears to be an important aspect of tumorigenesis. We evaluated the size of adipocytes in human adipose explants from normal (hRAN) and kidney cancer (hRAT); changes in the expression of WAT and BAT/beige markers in hRAN and hRAT; the expression of epithelial-mesenchymal transition (EMT) cell markers in human kidney tumor (786-O, ACHN and Caki-1); and non-tumor (HK-2) epithelial cell lines incubated with the conditioned media (CMs) of hRAN and hRAT. We observed that hRAT adipocytes showed a significantly minor size compared to hRAN adipocytes. Also, we observed that both Prdm16 and Tbx1 mRNA and the expression of UCP1, TBX1, PPARγ, PCG1α, c/EBPα LAP and c/EBPα LIP was significantly higher in hRAT than hRAN. Finally, we found an increase in vimentin and N-cadherin expression in HK-2 cells incubated for 24 h with hRAT-CMs compared to hRAN- and control-CMs. Furthermore, desmin and N-cadherin expression also increased significantly in 786-O when these cells were incubated with hRAT-CMs compared to the value observed with hRAN- and control-CMs. We observed a significant decrease in E-cadherin expression in the ACHN cell line incubated with hRAT-CMs versus hRAN- and control-CMs. However, we did not observe changes in E-cadherin expression in HK-2, 786-O or Caki-1. The results obtained, together with the results previously published by our group, allow us to conclude that perirenal white adipose tissue browning contributes to tumor development in kidney cancer. In addition, hRAT-CMs increases the expression of mesenchymal markers in renal epithelial cells, which could indicate a regulation of EMT due to this adipose tissue.

Cladosporols A and B, two natural peroxisome proliferator-activated receptor gamma (PPARγ) agonists, inhibit adipogenesis in 3T3-L1 preadipocytes and cause a conditioned-culture-medium-dependent arrest of HT-29 cell proliferation

BACKGROUND

Obesity and type 2 diabetes mellitus, which are widespread throughout the world, require therapeutic interventions targeted to solve clinical problems (insulin resistance, hyperglycaemia, dyslipidaemia and steatosis). Several natural compounds are now part of the therapeutic repertoire developed to better manage these pathological conditions. Cladosporols, secondary metabolites from the fungus Cladosporium tenuissimum, have been characterised for their ability to control cell proliferation in human colon cancer cell lines through peroxisome proliferator-activated receptor gamma (PPARγ)-mediated modulation of gene expression. Here, we report data concerning the ability of cladosporols to regulate the differentiation of murine 3T3-L1 preadipocytes.

METHODS

Cell counting and MTT assay were used for analysing cell proliferation. RT-PCR and Western blotting assays were performed to evaluate differentiation marker expression. Cell migration was analysed by wound-healing assay.

RESULTS

We showed that cladosporol A and B inhibited the storage of lipids in 3T3-L1 mature adipocytes, while their administration did not affect the proliferative ability of preadipocytes. Moreover, both cladosporols downregulated mRNA and protein levels of early (C/EBPα and PPARγ) and late (aP2, LPL, FASN, GLUT-4, adiponectin and leptin) differentiation markers of adipogenesis. Finally, we found that proliferation and migration of HT-29 colorectal cancer cells were inhibited by conditioned medium from cladosporol-treated 3T3-L1 cells compared with the preadipocyte conditioned medium.

CONCLUSIONS

To our knowledge, this is the first report describing that cladosporols inhibit in vitro adipogenesis and through this inhibition may interfere with HT-29 cancer cell growth and migration.

GENERAL SIGNIFICANCE

Cladosporols are promising tools to inhibit concomitantly adipogenesis and control colon cancer initiation and progression.

Quantitative Proteomics Identifies Secreted Diagnostic Biomarkers as well as Tumor-Dependent Prognostic Targets for Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the third most common and most malignant urological cancer, with a 5-year survival rate of 10% for patients with advanced tumors. Here, we identified 10,160 unique proteins by in-depth quantitative proteomics, of which 955 proteins were significantly regulated between tumor and normal adjacent tissues. We verified four putatively secreted biomarker candidates, namely, PLOD2, FERMT3, SPARC, and SIRPα, as highly expressed proteins that are not affected by intratumor and intertumor heterogeneity. Moreover, SPARC displayed a significant increase in urine samples of patients with ccRCC, making it a promising marker for the detection of the disease in body fluids. Furthermore, based on molecular expression profiles, we propose a biomarker panel for the robust classification of ccRCC tumors into two main clusters, which significantly differed in patient outcome with an almost three times higher risk of death for cluster 1 tumors compared with cluster 2 tumors. Moreover, among the most significant clustering proteins, 13 were targets of repurposed inhibitory FDA-approved drugs. Our rigorous proteomics approach identified promising diagnostic and tumor-discriminative biomarker candidates which can serve as therapeutic targets for the treatment of ccRCC. IMPLICATIONS: Our in-depth quantitative proteomics analysis of ccRCC tissues identifies the putatively secreted protein SPARC as a promising urine biomarker and reveals two molecular tumor phenotypes.

Body Mass Index in Patients Treated with Cabozantinib for Advanced Renal Cell Carcinoma: A New Prognostic Factor?

We analyzed the clinical and pathological features of renal cell carcinoma (RCC) patients treated with cabozantinib stratified by body mass index (BMI). We retrospectively collected data from 16 worldwide centers involved in the treatment of RCC. Overall survival (OS) and progression-free survival (PFS) were analyzed using Kaplan–Meier curves. Cox proportional models were used at univariate and multivariate analyses. We collected data from 224 patients with advanced RCC receiving cabozantinib as second- (113, 5%) or third-line (111, 5%) therapy. The median PFS was significantly higher in patients with BMI ≥ 25 (9.9 vs. 7.6 months, p < 0.001). The median OS was higher in the BMI ≥ 25 subgroup (30.7 vs. 11.0 months, p = 0.003). As third-line therapy, both median PFS (9.2 months vs. 3.9 months, p = 0.029) and OS (39.4 months vs. 11.5 months, p = 0.039) were longer in patients with BMI ≥ 25. BMI was a significant predictor for both PFS and OS at multivariate analysis. We showed that a BMI ≥ 25 correlates with longer survival in patients receiving cabozantinib. BMI can be easily assessed and should be included in current prognostic criteria for advanced RCC.

The tumour microenvironment and metabolism in renal cell carcinoma targeted or immune therapy

Renal cell carcinoma (RCC) is one of the most common tumours of the urinary system, and is insidious and not susceptible to chemoradiotherapy. As the most common subtype of RCC (70-80% of cases), clear cell renal cell carcinoma (ccRCC) is characterized by the loss of von Hippel-Lindau and the accumulation of robust lipid and glycogen. For advanced RCC, molecular-targeted drugs, tyrosine kinase inhibitors (TKIs) and the immune checkpoint inhibitors (ICIs) have been increasingly recommended and investigated. Due to the existence of a highly dynamic, adaptive and heterogeneous tumour microenvironment (TME), and due to the glucose and lipid metabolism in RCC, this cancer may be accompanied by various types of resistance to TKIs and ICIs. With the increased production of lactate, nitric oxide, and other new by-products of metabolism, novel findings of the TME and key metabolic enzymes drived by HIF and other factors have been increasingly clarified in RCC carcinogenesis and therapy. However, there are few summaries of the TME and tumour metabolism for RCC progression and therapy. Here, we summarize and discuss the relationship of the important implicated characteristics of the TME as well as metabolic molecules and RCC carcinogenesis to provide prospects for future treatment strategies to overcome TME-related resistance in RCC.