Methotrexate (MTX) belongs to a group of medicines known as antimetabolites. It is commonly used in the treatment of malignant diseases and is prescribed in autoimmune and chronic inflammatory disorders. Along with its effective therapeutic power, MTX has adverse effects on several organs, including the kidney. The organic anion transporter 5 (Oat5) is exclusively localized in the renal apical membrane. Oat5 urinary excretion was proposed as an early biomarker in ischemic and nephrotoxic-induced kidney injury and in renal damage due to vascular calcification in preclinical models. The aim of this study was to evaluate Oat5 renal expression and urinary excretion in rats 48 h after the exposure to different doses of MTX, in comparison with traditional markers of renal injury, such as creatinine and urea plasma levels, protein urinary levels, urinary alkaline phosphatase (AP) activity, fractional excretion of water (FEWater) and renal histology. Male Wistar rats were treated with a single intraperitoneal injection of MTX at different dosages: 40-80-120-180-360 mg per kg b.w. (M40, M80, M120, M180, M360, n = 4, respectively) and experiments were carried out 48 h after MTX administration. Oat5 renal expression was evaluated by western blotting and immunohistochemistry. Traditional parameters were only modified at the higher MTX dose (M360). Conversely, Oat5 urinary excretion was elevated at the middle dose of 80 mg per kg b.w. Oat5 renal expression was modified at the highest dose as well, both in homogenates and in apical membranes. These results suggest that Oat5 urinary excretion might serve as an early biomarker of MTX-induced kidney injury.

Recently, several reports demonstrated the efficacy of neoadjuvant chemotherapy (NAC) or chemoradiotherapy (NACRT) for patients with borderline resectable (BRPC) and locally advanced unresectable pancreatic carcinoma (LAPC). The aim of this study was to evaluate the treatment response after NACRT, especially for nerve plexuses, and the optimal resection area for superior mesenteric artery nerve plexuses in BRPC and LAPC patients after NACRT.A total of 17 patients with BRPC and LAPC received preoperative gemcitabine-based NACRT. The numbers of BRPC and LAPC patients were 13 and 4, respectively. We evaluated nerve plexus invasion by CT before and after NACRT, decided on the resection area of plexus invasion in SMA before NACRT, and compared the preoperative evaluation and clinicopathological findings.In the plexus of the supra-mesenteric artery (pl-SMA), arterial nerve plexus invasion, in cases <90°, all patients showed the absence of residual cancer in the resected specimen after NACRT. In cases between 90° and 180°, 1 of 2 patients (50%) showed nerve plexus invasion. In cases over 180°, all patients showed nerve plexus invasion. We could perform R0 resection in all 10 cases, and pl-SMA invasion disappeared in 6 of 7 BRPC patients.We demonstrated the relationship between the angle of nerve plexus tumor invasion and treatment effect after NACRT. We could perform R0 resection in all pl-SMA invasion cases, deciding on the resection area of pl-SMA based on CT before NACRT.