Purpose: Renal cell carcinoma (RCC) is the most common renal cancer in adults and includes several subtypes that may be distinguished by their histology, genetic background, clinical course and responses to treatment. Human telomerase reverse transcriptase (hTERT), a crucial enzyme for telomere maintenance, has been linked to RCC development. The purpose of this study was to search for genetic and epigenetic alterations in hTERT (promoter mutations and methylation and gene amplification), and to establish a possible association between molecular and clinico-pathological characteristics of RCC.
Methods: DNA was extracted from 31 formalin-fixed, paraffin-embedded tumor samples and 23 blood samples from 54 patients with RCC. Polymerase chain reaction (PCR) products were sequenced and analyzed using the Sequencher software. HTERT amplification was determined by quantitative PCR, while the promoter methylation status was assessed by methylation specific PCR. Statistical analysis was performed using SPSS.
Results: No mutations could be detected in the hTERT promoter but only a single nucleotide polymorphism (SNP) (-245 T>C). In 54 analyzed RCC cases, the variant allele C was present in homozygous or heterozygous form in 48% of the patients. The C allele was significantly more frequent in low grade tumors (p=0.046). Gene amplification was detected in 19.4% of the 31 RCCs and hTERT methylation in 54.8% of the 31 samples. An association was established between methylation and histological type of RCC (p=0.047).
Conclusions: HTERT seems to be implicated in RCC pathogenesis since the promoter polymorphism exerts a modulation effect on tumor behavior. In addition, hTERT promoter methylation status is related to RCC histology.