Genetic alterations of HER genes in chromophobe renal cell carcinoma.

Chromophobe (ch) renal cell carcinoma (RCC) is the 3rd most common subtype of RCC and occurs in 5% of all RCCs. Although chRCC generally demonstrates more favorable outcomes compared with other subtypes of RCC, there is a 6-7% probability of tumor progression and metastasis in this disease. The subclassification of a more aggressive subtype of chRCC may be useful for the management of this cancer. The Erb-B2 receptor tyrosine kinase 2 [also known as human epidermal growth factor receptor (HER) 2] gene has been reported to be important in chRCC. The present study aimed to further investigate the abnormalities of the HER family genes and their potential association with chRCC. Fluorescence in situ hybridization was performed on 11 chRCC tissue specimens, and the Spearman's rank correlation coefficient analysis was used to assess the results. The loss of one copy of the HER2 and HER4 genes was observed to be the major alteration of the tumor cells in all chRCC cases. Statistical data indicated that loss of the HER2 gene was strongly correlated with loss of the HER4 gene (P=0.019). The findings of previous studies were also combined for analysis, and were consistent with those of the present study. In addition, the amplification of HER1 was also strongly correlated with the amplification of HER4 (P=0.004). Furthermore, a high percentage of genetic structural rearrangements was observed in HER3 genes, which was significantly associated with amplification of HER2 (P=0.005). Certain alterations in the HER gene family were also noted as a phenomenom in chRCC. Therefore, the characterization of the underlying aberrant functions of HER genes may be of interest for additional studies in the context of using HER genes to distinguish between RCC subtypes in order to establish improved treatment guidelines.