| dc.description.abstract | The occurrence and death rates of renal cell carcinoma (RCC) are increasing each year.
However, this disease is mostly asymptomatic at an early stage but highly metastatic.
Among the RCC subtypes, the clear-cell RCC (ccRCC) is the most prevalent and
accounts for the most deaths. Importantly, more than 70% of the ccRCC cases carry
either genomic or epigenetic defects in the von Hippel-Lindau tumor suppressor gene
(VHL). Our laboratory has previously established a mouse model containing
conditional inactivation of the Vhlh (the mouse VHL locus) gene in the kidney tubules,
which results in hyperplastic, inflammatory, and fibrotic lesions in the kidneys. Initial
microarray analysis identified high expression of HAVCR-1 in mutant mouse kidneys
compared to wild-type. HAVCR-1 (also known as KIM-1 or TIM-1) is a type 1
membrane protein and has been recognized as a diagnostic marker for kidney disease.
Recently, several studies have also shown that KIM-1 is expressed abnormally in
human cancers, including ccRCC. This leads us to hypothesize that KIM-1 may
contribute to the progression of ccRCC. However, the functional correlation between
KIM-1 and VHL are still unknown. Here, we generated KIM-1 knockdown in proximal
tubule epithelial cell line (HK-2) with or without VHL knockdown, and RNA sequencing analysis was performed to analyze the differentially expressed genes
(DEGs) comparing control, VHL knockdown, KIM-1 knockdown, and VHL-KIM-1
double knockdown. Many DEGs were found, and the enrichment analysis using the
Ingenuity Pathway Analysis (IPA) software on DEGs showed that in VHL knockdown
cells, inflammatory, proliferative, and mesenchymal transition pathways are increased,
while cell death and apoptosis pathways are reduced, consistent with the tumorigenic
property of these VHL-defective kidney cells. Heatmap clustering analysis revealed 4
distinct groups of genes that show different expression patterns in different gene
knockdown backgrounds, suggesting the functional relationship between VHL and
KIM-1 is probably not a simple linear pathway. Interestingly, cell migration was tested
by wound healing experiment, and we found that KIM-1 knockdown in VHL
knockdown cells can inhibit cell migration. Our results showed that double knockdown
of KIM-1 and VHL in HK-2, compared with VHL single knockdown, reduces the
expression of multiple cytokines-induced inflammation pathways, and influences
tumor progression pathways. Thereby, these results together point to a new ccRCC or
renal cancer treatment targets in general. | en_US |