VEGFR-1 Expression Relates to Fuhrman Nuclear Grade of Clear Cell Renal Cell Carcinoma

Expression of growth factors and their receptors in the primary renal cell carcinoma: new data and review

Introduction

The aim of our study was to investigate expression levels and the prognostic value of multiple growth factors and their receptors in the primary tumor cells of renal cell carcinoma (RCC).

Material and methods

Expression of vascular endothelial growth factor (VEGF)A, fibroblast growth factor (FGF)2, vascular endothelial growth factor receptor (VEGFR)1, VEGFR2, FGFR1, FGFR2, platelet-derived growth factor receptor (PDGFR)α, and PDGFRβ was investigated in 65 primary RCC specimens by immuhistochemical staining using the appropriate antibodies. Expression levels were evaluated by the semi-quantitative method. A search for correlations of expression levels of investigated growth factors and receptors with RCC features and patients outcomes was performed.

Results

Expression of all growth factors and their receptors was detected both on the surface and in the cytoplasm of the primary tumor cells in RCC patients. The expression of all analyzed factors was interconnected. FGFR2 expression correlated with the largest number of other growth factors and receptors. A strong correlation was revealed between high expression of the studied markers, high Fuhrman grade, and advanced RCC stages. In a univariate analysis overexpression of VEGFR2 (p <0.0001) and FGFR2 (p = 0.014) had negative influence on cancer-specific survival.

Conclusions

Expression of growth factors and tyrosine kinase receptors in the primary tumor cells is strongly interconnected and associated with unfavorable features of RCC.

ACAT1 and Metabolism-Related Pathways Are Essential for the Progression of Clear Cell Renal Cell Carcinoma (ccRCC), as Determined by Co-expression Network Analysis

Kidney cancer ranks as one of the top 10 causes of cancer death; this cancer is difficult to detect, difficult to treat, and poorly understood. The most common subtype of kidney cancer is clear cell renal cell carcinoma (ccRCC) and its progression is influenced by complex gene interactions. Few clinical studies have investigated the molecular markers associated with the progression of ccRCC. In this study, we collected microarray profiles of 72 ccRCCs and matched normal samples to identify differentially expressed genes (DEGs). Then a weighted gene co-expression network analysis (WGCNA) was conducted to identify co-expressed gene modules. By relating all co-expressed modules to clinical features, we found that the brown module and Fuhrman grade had the highest correlation (r = -0.8, p = 1e-09). Thus, the brown module was regarded as a clinically significant module and subsequently analyzed. Functional annotation showed that the brown module focused on metabolism-related biological processes and pathways, such as fatty acid oxidation and amino acid metabolism. We then performed a protein-protein interaction (PPI) network to identify the hub nodes in the brown module. It is worth noting that only one candidate, acetyl-CoA acetyltransferase (ACAT1), was considered to be the final target most relevant to the Fuhrman grade of ccRCC, by applying the intersection of hub genes in the co-expressed network and the PPI network. ACAT1 was subsequently validated using another two external microarray datasets and the TCGA dataset. Intriguingly, validation results indicated that ACAT1 was negatively correlated with four grades of ccRCC, which was also consistent with our results from qRT-PCR analysis and immunohistochemistry staining of clinical samples. Overexpression of ACAT1 inhibited the proliferation and migration of human ccRCC cells in vitro. In addition, the Kaplan-Meier survival curve showed that patients with a lower expression of ACAT1 showed a significantly lower overall survival rate and disease-free survival rate, indicating that ACAT1 could act as a prognostic and recurrence/progression biomarker of ccRCC. In summary, we found and confirmed that ACAT1 might help to identify the progression of ccRCC, which might have important clinical implications for enhancing risk stratification, therapeutic decision, and prognosis prediction in ccRCC patients.

Identification of Biomarkers Associated With Pathological Stage and Prognosis of Clear Cell Renal Cell Carcinoma by Co-expression Network Analysis

Clear cell renal cell carcinoma (ccRCC) is the most common subtype among renal cancer whose prognostic is affected by the tumor progression associated with complex gene interactions. However, there is currently no available molecular markers associated with ccRCC progression and used or clinical application. In our study, microarray data of 101 ccRCC samples and 95 normal kidney samples were analyzed and 2,425 differentially expressed genes (DEGs) were screened. Weighted gene co-expression network analysis (WGCNA) was then conducted and 11 co-expressed gene modules were identified. Module preservation analysis revealed that two modules (red and black) were found to be most stable. In addition, Pearson's correlation analysis identified the module most relevant to pathological stage(patho-module) (r = 0.44, p = 3e-07). Functional enrichment analysis showed that biological processes of the patho-module focused on cell cycle and cell division related biological process and pathway. In addition, 29 network hub genes highly related to ccRCC progression were identified from the stage module. These 29 hub genes were subsequently validated using 2 other independent datasets including GSE53757 (n = 72) and TCGA (n = 530), and the results indicated that all hub genes were significantly positive correlated with the 4 stages of ccRCC progression. Kaplan-Meier survival curve showed that patients with higher expression of each hub gene had significantly lower overall survival rate and disease-free survival rate, indicating that all hub genes could act as prognosis and recurrence/progression biomarkers of ccRCC. In summary, we identified 29 molecular markers correlated with different pathological stages of ccRCC. They may have important clinical implications for improving risk stratification, therapeutic decision and prognosis prediction in ccRCC patients.

Involvement of ion channels and transporters in carcinoma angiogenesis and metastasis

Angiogenesis is a finely tuned process, which is the result of the equilibrium between pro- and antiangiogenic factors. In solid tumor angiogenesis, the balance is highly in favor of the production of new, but poorly functional blood vessels, initially intended to provide growing tumors with nutrients and oxygen. Among the numerous proteins involved in tumor development, several types of ion channels are overexpressed in tumor cells, as well as in stromal and endothelial cells. Ion channels thus actively participate in the different hallmarks of cancer, especially in tumor angiogenesis and metastasis. Indeed, from their strategic localization in the plasma membrane, ion channels are key operators of cell signaling, as they sense and respond to environmental changes. This review aims to decipher how ion channels of different families are intricately involved in the fundamental angiogenesis and metastasis hallmarks, which lead from a nascent tumor to systemic dissemination. An overview of the possible use of ion channels as therapeutic targets will also be given, showing that ion channel inhibitors or specific antibodies may provide effective tools, in the near future, in the treatment of carcinomas.