A Kinome-wide screen identifies a CDKL5-SOX9 regulatory axis in epithelial cell death and kidney injury

© 2020, The Author(s). Renal tubular epithelial cells (RTECs) perform the essential function of maintaining the constancy of body fluid composition and volume. Toxic, inflammatory, or hypoxic-insults to RTECs can cause systemic fluid imbalance, electrolyte abnormalities and metabolic waste accumulation- manifesting as acute kidney injury (AKI), a common disorder associated with adverse long-term sequelae and high mortality. Here we report the results of a kinome-wide RNAi screen for cellular pathways involved in AKI-associated RTEC-dysfunction and cell death. Our screen and validation studies reveal an essential role of Cdkl5-kinase in RTEC cell death. In mouse models, genetic or pharmacological Cdkl5 inhibition mitigates nephrotoxic and ischemia-associated AKI. We propose that Cdkl5 is a stress-responsive kinase that promotes renal injury in part through phosphorylation-dependent suppression of pro-survival transcription regulator Sox9. These findings reveal a surprising non-neuronal function of Cdkl5, identify a pathogenic Cdkl5-Sox9 axis in epithelial cell-death, and support CDKL5 antagonism as a therapeutic approach for AKI

Conjunctive Therapy of Cisplatin With the OCT2 Inhibitor Cimetidine: Influence on Antitumor Efficacy and Systemic Clearance

The organic cation transporter 2 (OCT2) regulates uptake of cisplatin in proximal tubules, and inhibition of OCT2 protects against severe cisplatin-induced nephrotoxicity. However, it remains uncertain whether potent OCT2 inhibitors, such as cimetidine, can influence the antitumor properties and/or disposition of cisplatin. Using an array of preclinical assays, we found that cimetidine had no effect on the uptake and cytotoxicity of cisplatin in ovarian cancer cells with high OCT2 mRNA levels (IGROV-1 cells). Moreover, the antitumor efficacy of cisplatin in mice bearing luciferase-tagged IGROV-1 xenografts was unaffected by cimetidine (P = 0.39). Data obtained in 18 patients receiving cisplatin (100 mg/m(2)) in a randomized crossover fashion with or without cimetidine (800 mg x 2) revealed that cimetidine did not alter exposure to unbound cisplatin, a marker of antitumor efficacy (4.37 vs. 4.38 mu g.h/ml; P = 0.86). These results support the future clinical exploration of OCT2 inhibitors as specific modifiers of cisplatin-induced nephrotoxicity

Human OCT2 variant c.808G > T confers protection effect against cisplatin-induced ototoxicity

Aim: Assuming that genetic variants of the SLC22A2 and SLC31A1 transporter affect patients' susceptibility to cisplatin-induced ototoxicity, we compared the distribution of 11 SLC22A2 variants and the SLC31A1 variant rs10981694 between patients with and without cisplatin-induced ototoxicity. Patients & methods: Genotyping was performed in 64 pediatric patients and significant findings were re-evaluated in 66 adults. Results: The SLC22A2 polymorphism rs316019 (c.808G>T; Ser270Ala) was significantly associated with protection from cisplatin-induced ototoxicity in the pediatric (p = 0.022) and the adult cohort (p = 0.048; both: Fisher's exact test). This result was confirmed by multiple logistic regression analysis accounting for age which was identified as a relevant factor for ototoxicity as well (rs316019: OR [G/T vs G/G] = 0.12, p = 0.009; age: OR [per year]: 0.84, p = 0.02). Conclusion: These results identified rs316019 as potential pharmacogenomic marker for cisplatin-induced ototoxicity and point to a critical role of SLC22A2 for cisplatin transport in humans and its contribution to the organ specific side effects of this drug

Proximal Tubular Secretion of Creatinine by Organic Cation Transporter OCT2 in Cancer Patients

Purpose: Knowledge of transporters responsible for the renal secretion of creatinine is key to a proper interpretation of serum creatinine and/or creatinine clearance as markers of renal function in cancer patients receiving chemotherapeutic agents. Experimental Design: Creatinine transport was studied in transfected HEK293 cells in vitro and in wildtype mice and age-matched organic cation transporter 1 and 2-deficient [Oct1/2(-/-)] mice ex vivo and in vivo. Clinical pharmacogenetic and transport inhibition studies were done in two separate cohorts of cancer patients. Results: Compared with wild-type mice, creatinine clearance was significantly impaired in Oct1/2(-/-) mice. Furthermore, creatinine inhibited organic cation transport in freshly isolated proximal tubules from wild-type mice and humans, but not in those from Oct1/2(-/-) mice. In a genetic association analysis (n = 590), several polymorphisms around the OCT2/SLC22A2 gene locus, including rs2504954 (P = 0.000873), were significantly associated with age-adjusted creatinine levels. Furthermore, in ca Conclusions: Collectively, this study shows that OCT2 plays a decisive role in the renal secretion of creatinine. This process can be inhibited by OCT2 substrates, which impair the usefulness of creatinine as a marker of renal function. Clin Cancer Res; 18(4); 1101-8. (C)2012 AACR

CYP3A4*22 Genotype and Systemic Exposure Affect Paclitaxel-Induced Neurotoxicity

Purpose: Paclitaxel is used for the treatment of several solid tumors and displays a high interindividual variation in exposure and toxicity. Neurotoxicity is one of the most prominent side effects of paclitaxel. This study explores potential predictive pharmacokinetic and pharmacogenetic determinants for the onset and severity of neurotoxicity. Experimental Design: In an exploratory cohort of patients (n = 261) treated with paclitaxel, neurotoxicity incidence, and severity, pharmacokinetic parameters and pharmacogenetic variants were determined. Paclitaxel plasma concentrations were measured by high-performance liquid chromatography or liquid chromatography/tandem mass spectrometry, and individual pharmacokinetic parameters were estimated from previously developed population pharmacokinetic models by nonlinear mixed effects modeling. G Results: Exposure to paclitaxel ((log)AUC) was correlated with severity of neurotoxicity (P 0.05) of paclitaxel in males or females. Other genetic variants displayed no association with neurotoxicity. In the subsequent independent validation cohort, CYP3A4*22 carrie Conclusions: Paclitaxel exposure showed a relationship with the severity of paclitaxel-induced neurotoxicity. In this study, female CYP3A4*22 carriers had increased risk of developing severe neurotoxicity during paclitaxel therapy. These observations may guide future individualization of paclitaxel treatment. (C)2013 AACR