Homozygous G/G variant of SNP309 in the human MDM2 gene is associated with earlier tumor onset in Caucasian female renal cell carcinoma patients.

Human mouse double minute 2 (Mdm2) plays an essential role in the regulation of the tumor suppressor p53. The G/G variant of SNP309 was shown to increase Mdm2 mRNA/protein expression and to be associated with an increased risk and earlier onset of different cancers in Asian populations. However, the frequency and impact of these G/G variants have not been studied in Caucasian renal cell carcinoma (RCC) patients. Therefore, we analyzed an unselected German cohort of 197 consecutive RCC patients and detected the G/G variant in 18 (9.1%) patients, the G/T variant in 116 (58.9%) patients and the T/T variant in 63 (32.0%) patients. Studying the association between age at tumor onset and SNP309 genotypes, no correlation was detected in the entire RCC cohort or among the male RCC patients. However, the female G/G patients (median age 59.5 years) were diagnosed 13.5 years earlier than the T/T females (median age 73 years). When separating all females into two groups at their median age (68 years), 7 and 1 patients with the G/G variant and 9 and 13 patients with the T/T variant were noted in these age groups (P=0.024). To study the age dependency of tumor onset further, a second, age-selected cohort of 205 RCC patients was investigated, which comprised especially young and old patients. Interestingly, the G/G type occurred more often at lower tumor stages and tumor grades compared with higher stages (P=0.039 and 0.004, respectively). In females, the percentage of the G/G variant was only slightly higher in the younger age group, whereas in males, the percentage of the G/G variant was remarkably higher in the younger age group (19.4% vs 8.0%). In summary, female Caucasian RCC patients with the MDM2 SNP309 G/G genotype showed significantly earlier tumor onset than patients with the wild-type T/T genotype.

Immunohistochemical marker panel differentiates between the three most common subtypes of renal cell carcinoma independent from histomorphologic criteria.

To develop a reliable immunohistochemical marker panel differentiating between the three most common renal cell carcinoma (RCC) subtypes without inclusion of histomorphologic criteria we investigated protein expression of vimentin, glutathione S-transferase alpha (GST-α), CD10, CD117 (C-KIT), carbonic anhydrase 2 (CAII), parvalbumin, alpha-methyl-CoA-racemase (AMACR), and cytokeratin-19 (CK 19) in 65 age and stage matched trios of clear cell carcinoma, papillary renal carcinoma and chromophobe renal carcinoma using tissue microarrays. All markers displayed significant differential expression among the subtypes (p < 0.001) except CAII (p = 0.192). According to positive (LR+) and negative (LR-) likelihood ratio, six markers (CD10, GST-α, AMACR, CK19, C-KIT and arvalbumin) demonstrated acceptable or good values to detect certain subtypes of RCC, but failed in terms of ruling out the respective subtypes. Based on the individual performance of these six markers, we combined them and reviewed each single case: LR+ for detection of clear cell RCC considerably increased by application of the six marker panel, but did not exceed 10. LR- was still >0.1; in case of papillary RCC LR+ rose beyond 10, but LR- remained >0.1. LR+ for recognition of chromophobe RCC rose far beyond 10, but LR- remained >0.1. Thus, the panel can reliably recognize two main RCC subtypes without inclusion of histomorphologic features. Further improvement is needed for consistent detection of clear cell RCC and for dependably ruling out all three main subtypes as well as identification of rare variants and benign lesions like oncocytoma.

Mutational activation of FGFR3: no involvement in the development of renal cell carcinoma.

BACKGROUND: Somatic point mutations in the fibroblast growth factor receptor 3 (FGFR3) gene have been identified in certain types of urological cancers, especially urothelial carcinoma of the bladder and the renal pelvis, and could be correlated with a favourable outcome. However, comprehensive data on the FGFR3 mutation status in renal cell carcinoma (RCC) are still missing. METHODS: In order to investigate a possible role for FGFR3 mutations in renal cell carcinogenesis, we performed a sequence-based mutational analysis of FGFR3 in 238 primary RCC. The cohort obtained the common RCC subtypes including 101 clear cell, 50 papillary and 68 chromophobe RCC specimens. The analysed regions encompassed all FGFR3 point mutations previously described in epithelial tumours and other noncutaneous epithelial malignancies. RESULTS: No mutations were detected in any renal tumour type examined, and all cases showed wild-type sequence. CONCLUSION: Our results argue against an involvement of mutational activation of FGFR3 in the development of RCC. A recently described cystic renal dysplasia in a patient with thanatophoric dysplasia type 1 due to a germ line FGFR3 mutation might portend to an involvement of mutational FGFR3 activation in renal cyst formation, but this speculation needs further evaluation.