The cysteines of the extracellular loop are crucial for trafficking of human organic cation transporter 2 to the plasma membrane and are involved in oligomerization.

Human organic cation transporter 2 (hOCT2) is involved in transport of many endogenous and exogenous organic cations, mainly in kidney and brain cells. Because the quaternary structure of transmembrane proteins plays an essential role for their cellular trafficking and function, we investigated whether hOCT2 forms oligomeric complexes, and if so, which part of the transporter is involved in the oligomerization. A yeast 2-hybrid mating-based split-ubiquitin system (mbSUS), fluorescence resonance energy transfer, Western blot analysis, cross-linking experiments, immunofluorescence, and uptake measurements of the fluorescent organic cation 4-(4-(dimethylamino)styryl)-N-methylpyridinium were applied to human embryonic kidney 293 (HEK293) cells transfected with hOCT2 and partly also to freshly isolated human proximal tubules. The role of cysteines for oligomerization and trafficking of the transporter to the plasma membranes was investigated in cysteine mutants of hOCT2. hOCT2 formed oligomers both in the HEK293 expression system and in native human kidneys. The cysteines of the large extracellular loop are important to enable correct folding, oligomeric assembly, and plasma membrane insertion of hOCT2. Mutation of the first and the last cysteines of the loop at positions 51 and 143 abolished oligomer formation. Thus, the cysteines of the extracellular loop are important for correct trafficking of the transporter to the plasma membrane and for its oligomerization.

Characterization and risk stratification of prostate cancer in patients undergoing radical cystoprostatectomy.

OBJECTIVE: To describe the prevalence of incidental prostate cancer in patients undergoing radical cystoprostatectomy for bladder malignancy; to quantify the association between incidental prostate cancer and mortality in these patients; and to quantify the association between incidental prostate cancer and age in radical cystoprostatectomy specimens. METHODS: Consecutive patients undergoing radical cystoprostatectomy for bladder malignancy at six academic institutions were assessed. End-points were the histological diagnosis of prostate cancer in the radical cystoprostatectomy specimens and mortality. The association between incidental prostate cancer and mortality was calculated by multivariable Cox regression, and the association between age and the occurrence of prostate cancer was calculated by logistic regression. RESULTS: A total of 1122 patients (aged 65.6 ± 10 years) were included in this analysis. Prostate cancer was detected in 17.8% (n = 200) of the cystoprostatectomy specimens. After multivariable adjustment, prostate cancer was significantly associated with mortality (hazard ratio 1.27, 95% confidence interval 1.03-1.56). There was a significant association between age and the presence of prostate cancer in the cystoprostatectomy specimen. The odds ratio for the presence of prostate cancer was 1.028 (95% confidence interval 1.011-1.045; P < 0.001) per each year after the age of 40 years. CONCLUSIONS: Concomitant prostate cancer is an independent prognostic factor for mortality after radical cystoprostatectomy for bladder cancer. When considering a prostate-sparing technique, urologists should consider that every fifth to sixth patient will present with a concomitant prostate cancer, and that after the age of 40 years, the odds of a concomitant prostate cancer increases by 2.8% per year, thus warranting a careful balance between the oncological risks and quality of life issues.

Final Results of a Non-Interventional Study Evaluating the Quality of Life in Second-line Treatment of Metastatic Renal Cell Carcinoma With Everolimus: The EVERPRO Study.

BACKGROUND: This study assessed the quality of life (QoL) and the implication of time effort of everolimus treatment in patients with metastatic renal cell carcinoma (mRCC). METHODS: Adult patients with mRCC were eligible for everolimus treatment after first-line vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors or bevacizumab therapy. The primary end-point, QoL, was assessed by means of the NCCN-FACT FKSI-19 questionnaire. RESULTS: In total, 202 patients (24% of female patients; median age, 71 years) were evaluable for QoL analyses. The median treatment duration was 4.4 months (95% CI, 3.8-5.3) and the median time to progression was 6 months (95% CI, 5.4-7.5). The median FKSI-19 total score remained stable during treatment (52.0 at therapy start, 55.0 at observation end). The median time effort spent on total therapy was 20 hours per patient. Most of the patients stated to have "no limitations," "a little" or "moderate" limitations in their daily, social, and professional lives. Two months after the start of treatment, 65 patients reported none or a little time burden due to therapy. CONCLUSIONS: QoL was maintained during the everolimus therapy and limitations as well as time effort were acceptable for most of the patients. The study supports previous findings on switching mode of action after anti-VEGFR-targeted therapy to a mammalian target of rapamycin inhibitor.

Cisplatin-induced renal injury is independently mediated by OCT2 and p53.

PURPOSE: Tubular secretion of cisplatin is abolished in mice deficient for the organic cation transporters Oct1 and Oct2 (Oct1/2(-/-)mice), and these animals are protected from severe cisplatin-induced kidney damage. Since tubular necrosis is not completely absent in Oct1/2(-/-)mice, we hypothesized that alternate pathways are involved in the observed injury. EXPERIMENTAL DESIGN: Studies were done in wild-type, Oct1/2(-/-), or p53-deficient animals, all on an FVB background, receiving cisplatin intraperitoneally at 15 mg/kg. Cisplatin metabolites were analyzed using mass spectrometry, and gene expression was assessed using Affymetrix microarrays and RT-PCR arrays. RESULTS: KEGG pathway analyses on kidneys from mice exposed to cisplatin revealed that the most significantly altered genes were associated with the p53 signaling network, including Cdnk1a and Mdm2, in both wild-type (P = 2.40 × 10(-11)) and Oct1/2(-/-)mice (P = 1.92 × 10(-8)). This was confirmed by demonstrating that homozygosity for a p53-null allele partially reduced renal tubular damage, whereas loss of p53 in Oct1/2(-/-)mice (p53(-/-)/Oct1/2(-/-)) completely abolished nephrotoxicity. We found that pifithrin-α, an inhibitor of p53-dependent transcriptional activation, inhibits Oct2 and can mimic the lack of nephrotoxicity observed in p53(-/-)/Oct1/2(-/-)mice. CONCLUSIONS: These findings indicate that (i) the p53 pathway plays a crucial role in the kidney in response to cisplatin treatment and (ii) clinical exploration of OCT2 inhibitors may not lead to complete nephroprotection unless the p53 pathway is simultaneously antagonized.