Dual role of KRT17: development of papillary renal cell tumor and progression of conventional renal cell carcinoma.

Expression of KRT17 has been described in multi-layered epithelia as well as in tumors derived from these cells. In cancers arising from KRT17 negative single layered epithelia neo-expression of KRT17 has been associated with tumor progression. To obtain more insight into the biology of kidney cancers we have investigated KRT17 expression by immunohistochemistry in normal kidney, in papillary preneoplastic lesions and in 151 papillary and 692 conventional renal cell carcinomas placed on tissue microarray. We found a positive staining in ureteric bud and collecting duct cells in foetal kidney, in all papillary preneoplastic lesions and also in 77% of the 151 papillary renal cell tumors indicating a continuos KRT17 expression during tumor development. The neo-expression of KRT17 in conventional renal cell carcinomas, which derives from KRT17 negative proximal tubules showed a significant correlation with postoperative tumor relapse (RR=2.50; 95% CI=1.59-3.94; p<0.001). In conclusion, the continuous expression of KRT17 from emerging fetal kidney tubules and microscopic pre-neoplastic lesions towards papillary renal cell tumors and its neo-expression in aggressive growing conventional renal cell carcinomas reflects the multiple function of KRT17 in kidney cancers with distinct natural history. This should be taken into account in clinical managements and therapy.

Embryonal Origin of Metanephric Adenoma and its Differential Diagnosis.

BACKGROUND/AIM: The association of Wilms' tumor (WT), papillary renal cell tumor (PRCT) and mucinous tubular and spindle cell carcinoma (MTSCC) with embryonal rests has already been documented, but the cellular origin of metanephric adenoma (MA) is not yet known. The aim of this study was to understand their developmental evolution and find diagnostic markers. MATERIALS AND METHODS: CD57, KRT7, AMACR, SCEL, WT1 and CDH17 expression was analysed by immunohistochemistry in the four types of tumors and the associated pre-neoplastic lesions. RESULTS: Immunohistochemistry was able to differentiate WT, MA, MTSCC and PRCT. A phenotypic correlation between MA and perilobar nephrogenic rest associated with WT was identified. CONCLUSION: Perilobar nephrogenic rest and MA arise from differentiation arrested cells of the proximal domain of the S-shape body. We propose that WT1, MA, MTSCC and PRCT derive from different forms of maturation arrested embryonal rests.

Shift of Keratin Expression Profile in End-stage Kidney Increases the Risk of Tumor Development.

BACKGROUND/AIM: Pre-neoplastic lesions and renal cell tumors of distinct pheno- and genotypes occur frequently in end-stage kidneys. The aim of this study was to investigate the role of KRT7 and KRT19 in this process, the expression of which was previously detected by Affymetrix GeneChip analysis. PATIENTS AND METHODS: Twelve end-stage kidneys were analyzed to find pre-neoplastic lesions and tumors and expression of KRT7 and KRT19 was examined by immunohistochemistry. RESULTS: A total of 17 tumors, 149 pre-neoplastic lesions, 179 simple or proliferative cysts >2 mm were identified. Diffuse expression of KRT7 and KRT19 was seen in all end-stage kidneys as well as in the vast majority of cysts, pre-neoplastic lesions and tumors. CONCLUSION: Our data indicates that de novo expression of KRT7 and KRT19 resulting in altered plasticity and stem cell characteristics of epithelial cells might be a crucial factor in increasing the risk of tumor development in end-stage kidneys.

Examination of PACAP-Like Immunoreactivity in Urogenital Tumor Samples.

Numerous studies investigated the localization of pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors in different tumors and described the effects of analogs on tumor growth to show its potential role in oncogenesis. Recently, our research group has found significantly lower levels of PACAP27-like immunorreactivity (LI) and PACAP38-LI in different human samples of primary small cell lung cancer and colon cancer compared to normal healthy tissues. There are only few human studies showing the presence of PACAP and its receptors in urogenital tumors; therefore, the aim of the present study was to compare PACAP-LI in different healthy and pathological human samples from urogenital organs (kidney, urinary bladder, prostate, testis) with radioimmunoassay (RIA) method. Similar to our earlier observations, the PACAP27-LI was significantly lower compared to PACAP38-LI in all samples. We did not find significant alterations in PACAP-LI between healthy and tumoral samples from the urinary bladder and testis. On the other hand, we found significantly lower PACAP38-LI level in kidney tumors compared with healthy tissue samples, and we showed higher PACAP27-LI in prostatic cancer compared to samples from benign prostatic hyperplasia. These data indicate that PACAP levels of different tissue samples are altered under pathological conditions suggesting a potential role of PACAP in the development of different urogenital tumors.