Alterations of ubiquitylation and sumoylation in conventional renal cell carcinomas after the Chernobyl accident: a comparison with Spanish cases.

We determined whether ubiquitylation and sumoylation processes are involved in conventional renal cell carcinogenesis associated with chronic, long-term, persistent low doses of ionizing radiation (IR) in patients living for more than 20 years in cesium-137 ((137)Cs)-contaminated areas after the Chernobyl accident in Ukraine. To this end, we assessed the immunohistochemical expression of ubiquitin (Ub), SUMO1, SUMO E2 conjugating enzyme Ubc9, and the cell cycle regulators p53, mdm2, and p14(ARF) in 38 conventional renal cell carcinomas from Ukrainian patients with different degrees of radiation exposure after the Chernobyl accident. As control cases, 18 conventional renal carcinoma (cRCC) tissues from a Spanish cohort were analyzed. No significant differences between the Ukrainian and Spanish groups were found regarding Ub overexpression, although being higher in the Ukrainian cases. Furthermore, this expression was inversely associated with SUMO1 and Ubc9, with no correlation with tumor nuclear grade. There was also a direct relationship between Ubc9 and inflammatory response. These findings do not allow us to consider the immunohistochemical expression of ubiquitylation and sumoylation as valuable markers for discriminating the effects of long-term, low-dose IR exposure in cRCC carcinogenesis.

Extracellular matrix alterations in conventional renal cell carcinomas by tissue microarray profiling influenced by the persistent, long-term, low-dose ionizing radiation exposure in humans.

The present study was carried out in order to examine molecular alterations of extracellular matrix (ECM), associated with cell-cell communication in conventional (clear-cell) renal cell carcinomas (cRCCs) influenced by persistent long-term, low-dose ionizing radiation (IR) exposure to patients living more than 19 years after the Chernobyl accident in Cesium 137 (137Cs)-contaminated areas of Ukraine. The ECM major components such as fibronectin, laminin, E-cadherin/beta-catenin complexes and p53 tumor suppressor gene protein, and transforming growth factor beta 1 (TGF-beta1) were immunohistochemically (IHC) evaluated in cRCCs from 59 Ukrainian patients, which represented 18 patients living in non-contaminated areas and 41 patients from 137Cs-contaminated areas. In contrast, a control group of 19 Spanish patients with analogue tumors were also investigated. For IHC evaluation, a tissue microarray technique was used. Decrease or loss and abnormal distribution of fibronectin, laminin, E-cadherin/beta-catenin complexes accompanied by elevated levels of p53 and TGF-beta1 were detected in the Ukrainian cRCCs from 137Cs-contaminated areas with statistically significant differences. Thus, our study suggests that chronic long-term, low-dose IR exposure might result in global remodeling of ECM components of the cRCCs with disruption in peri-epithelial stroma and epithelial basement membranes.

Alteration of Apoptotic Regulatory Molecules in Conventional Renal Cell Carcinoma Influenced by Chronic Long-term Low-dose Ionizing Radiation Exposure in Humans Revealed by Tissue Microarray.

Compared to the 19-year period subsequent to the Chernobyl accident, the morbidity of malignant renal tumors in the Ukraine has increased from 4.7 to 9.0 per 100,000 of the total population. Cesium 137 (137Cs), which accounts for 90% of the internal radioactivity in the Ukrainian population exposed to long-term low-dose radiation and 90% of the more labile pool of 137Cs, is excreted via the kidneys. Our present study aimed to evaluate the status of pro- and anti-apoptotic regulatory molecules in conventional renal cell carcinomas (cRCCs) in Ukrainian patients. To achieve this objective, Bcl-2, Bcl-x, BAX, death receptor (DR5) and transcriptional nuclear factor kappa B (NF-κB, with p50 and p65 subunits) were immunohistochemically investigated using a tissue microarray technique in cRCCs from a group of 56 Ukrainian patients, comprising 18 patients living in non-contaminated areas and 41 patients from 137Cs-contaminated areas. As a comparison, 19 Spanish patients with analogous tumors were also investigated. It was shown that BAX and DR5-positive cRCCs tended to increase among the Ukrainian patients living in the radio-contaminated areas, along with the suppression of anti-apoptotic molecules (Bcl-2 and Bcl-x) and with p65 and p50 overexpression in the same tumors. This study suggested that chronic long-term, low-dose radiation exposure might result in the alteration of the apoptotic regulatory mechanisms, which, in turn, could lead to enhanced tumor progression and resistance to apoptosis.

The INK4a /ARF locus: role in cell cycle control for renal cell epithelial tumor growth after the Chernobyl accident.

Previous studies have shown that during the period subsequent to the Chernobyl accident, increases in morbidity, aggressivity and proliferative activity of renal-cell carcinomas (RCCs) in Ukrainian patients were recognized. The present paper describes the molecular alterations of those tumor suppressor genes located on chromosome 9p21 ( INK4a/ARF locus and p15(INK4B)) in 26 primary renal-cell epithelial tumors from patients with different degrees of radiation exposure after the Chernobyl accident in Ukraine. Radiometric measurement of Cesium 137 ((137)Cs) was conducted with 1-day urine from all patients before surgery. Our results demonstrate that RCCs from patients living in the radio-contaminated areas showed aberrant hypermethylation of p14(ARF) and p16(INK4A) genes, associated with increased p38MAPK, p14(ARF), mdm2, cyclinD1 and Ki67 protein expression levels. Present findings show the possibility that chronic long-term low-dose radiation activates the INK4a/ARF locus, targeted by activation of the p38MAPK cascade. These actions could lead to disruptions and loss of cell cycle checkpoints and, thereby, to cellular transformation.

P16INK4A and p15INK4B gene alteration associated with oxidative stress in renal cell carcinomas after the chernobyl accident (pilot study).

Our study was undertaken to better understand the role of G1/S transition abnormalities in the malignant progression of renal cell carcinomas (RCCs), exposed to long-term low doses of ionizing radiation (IR), from patients living in radiocontaminated areas of the Ukraine after the Chernobyl accident. We studied p16 and p15 gene alteration in association with oxidative stress markers, including inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2). We analyzed 88 samples collected from 22 patients with RCCs and with different exposure to IR. Homozygous deletion of the p16 and p15 genes, as well as hypermethylation of the 5CpG island in the promoter region of the same genes, were analyzed by differential PCR and Methylation-Specific PCR respectively, in association with histopathology and immunohistochemical analysis of p16 and p15 proteins. COX2 and iNOS expression in the same tumors were likewise analyzed. Aberrant hypermethylation was observed in 7 (32%) and 5 (23%) cases accompanied, by immunohistochemical loss of expression for p16 and p15 genes respectively, in both high stage and grade tumors from patients living in radiocontaminated areas, this being especially outstanding for the p16 gene. An association with COX2 and less iNOS overexpression in the same tumors was observed. Our data suggest that inactivation of p16 gene, but not p15, induced by increased oxidative stress generated by persistent chronic exposure to IR, could be one of the major pathways responsible for RCCs malignant progression.