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Updated: Mar 12, 2026
The Use of Reverse Phase Protein Arrays RPPA to Explore Protein Expression Variation within Individual Renal Cell Cancers
Published on: January 22, 2013
Gene expression profile of renal cell carcinomas after neoadjuvant treatment with sunitinib: new pathways revealed
Carlos Dzik1, Sabrina T Reis2, Nayara I Viana2
1ICESP - Sao Paulo Cancer Institute, Sao Paulo - Brazil.
Background:
In renal cell carcinoma (RCC) of the clear cell type, inactivity of the VHL gene induces overexpression of HIF1 α and its targets, the tyrosine kinase receptors, promoting RCC development and progression. The discovery of tyrosine kinase inhibitors (TKIs) changed the treatment of these tumors. Other molecular pathways involved in the TKI mechanisms of action have not been described in the literature. The aim of our study was to elucidate alternative mechanisms of action of sunitinib in tumor tissue after neoadjuvant treatment of RCC.
Methods:
The gene expression profile was accessed using microarray (Affymetrix Human Genome U133 Plus 2.0 platform) and frozen RCC tissues collected from 5 patients with locally advanced non-metastatic tumors who underwent nephrectomy after being treated with 2 cycles of neoadjuvant sunitinib. The results were compared with matched controls comprising 6 patients with no neoadjuvant intervention.
Results:
There was underexpression of the majority of genes after sunitinib treatment. The lower expression levels of IGFBP1, CCL20, CXCL6 and FGB were confirmed by qRT-PCR in all cases. The downregulation of gene expression leads us to search for methylation as a mechanism of action of the TKI. IGFBP1 was shown to be methylated by methylation-sensitive high-resolution melting technique.
Conclusions:
The ultimate genetic effects of sunitinib may explain its actions as an antitumor drug that apparently suppresses the expression of important genes related to cell survival, adhesion, invasion and immunomodulation. The methylation of gene promoters was shown to be part of the mechanism of action of this class of drugs.
Insights
Sunitinib, a tyrosine kinase inhibitor (TKI), suppresses clear cell renal cell carcinoma (ccRCC) by downregulating key genes. Gene promoter methylation is identified as a novel mechanism of action for TKIs in ccRCC treatment.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Clear cell renal cell carcinoma (ccRCC) pathogenesis involves VHL gene inactivation, leading to HIF1α overexpression and promoting tumor growth.
- Tyrosine kinase inhibitors (TKIs) have revolutionized ccRCC treatment, but their full molecular mechanisms remain incompletely understood.
Purpose of the Study:
- To investigate alternative molecular mechanisms of sunitinib action in ccRCC tumor tissue following neoadjuvant therapy.
- To identify specific genes and pathways affected by sunitinib treatment in ccRCC.
Main Methods:
- Gene expression profiling using microarray analysis on ccRCC tissues from patients treated with neoadjuvant sunitinib.
- Quantitative real-time PCR (qRT-PCR) and methylation-sensitive high-resolution melting (MS-HRM) to validate gene expression changes and identify promoter methylation.
Main Results:
- Sunitinib treatment resulted in the underexpression of most genes in ccRCC tissues.
- Significant downregulation of IGFBP1, CCL20, CXCL6, and FGB was confirmed.
- Promoter methylation of the IGFBP1 gene was identified as a key mechanism contributing to its reduced expression.
Conclusions:
- Sunitinib exerts antitumor effects by suppressing critical genes involved in cell survival, adhesion, invasion, and immunomodulation in ccRCC.
- Gene promoter methylation represents a significant mechanism of action for sunitinib and potentially other TKIs in ccRCC treatment.
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