Urinary podocyte mRNAs precede microalbuminuria as a progression risk marker in human type 2 diabetic nephropathy
SCIENTIFIC REPORTS
Authors: Fukuda, Akihiro; Minakawa, Akihiro; Kikuchi, Masao; Sato, Yuji; Nagatomo, Masanao; Nakamura, Shuji; Mizoguchi, Tetsu; Fukunaga, Naoya; Shibata, Hirotaka; Naik, Abhijit S.; Wiggins, Roger C.; Fujimoto, Shouichi
Abstract
Earlier detection of progression risk in diabetic nephropathy will allow earlier intervention to reduce progression. The hypothesis that urinary pellet podocyte mRNA is a more sensitive progression risk marker than microalbuminuria was tested. A cross sectional cohort of 165 type 2 diabetics and 41 age and sex-matched controls were enrolled. Podocyte stress (Urinary pellet podocin:nephrin mRNA ratio), podocyte detachment (Urinary pellet podocin mRNA:creatinine ratio: UPPod:CR) and a tubular marker (Urinary pellet aquaporin 2:creatinine ratio) were measured in macro-albuminuric, micro-albuminuric and norm-albuminuric groups. eGFR was reassessed after 4 years in 124 available diabetic subjects. Urinary pellet podocyte and tubular mRNA markers were increased in all diabetic groups in cross-sectional analysis. After 4 years of follow-up univariable and multivariate model analysis showed that the only urinary markers significantly related to eGFR slope were UPPod:CR (P<0.01) and albuminuria (P<0.01). AUC analysis using K-fold cross validation to predict eGFR loss of >= 3 ml/min/1.73m(2)/year showed that UPPod:CR and albuminuria each improved the AUC similarly such that combined with clinical variables they gave an AUC=0.70. Podocyte markers and albuminuria had overlapping AUC contributions, as expected if podocyte depletion causes albuminuria. In the norm-albuminuria cohort (n=75) baseline UPPod:CR was associated with development of albuminuria (P=0.007) and, in the tertile with both normal kidney function (eGFR 84 +/- 11.7 ml/min/1.73m(2)) and norm-albuminuria at baseline, UPPod:CR was associated with eGFR loss rate (P=0.003). In type 2 diabetics with micro- or macro-albuminuria UPPod:CR and albuminuria were equally good at predicting eGFR loss. For norm-albuminuric type 2 diabetics UPPod:CR predicted both albuminuria and eGFR loss.
Gefitinib induces EGFR and alpha 5 beta 1 integrin co-endocytosis in glioblastoma cells
CELLULAR AND MOLECULAR LIFE SCIENCES
Authors: Blandin, Anne-Florence; Da Silva, Elisabete Cruz; Mercier, Marie-Cecile; Glushonkov, Oleksandr; Didier, Pascal; Dedieu, Stephane; Schneider, Cristophe; Devy, Jessica; Etienne-Selloum, Nelly; Dontenwill, Monique; Choulier, Laurence; Lehmann, Maxime
Abstract
Overexpression of EGFR drives glioblastomas (GBM) cell invasion but these tumours remain resistant to EGFR-targeted therapies such as tyrosine kinase inhibitors (TKIs). Endocytosis, an important modulator of EGFR function, is often dysregulated in glioma cells and is associated with therapy resistance. However, the impact of TKIs on EGFR endocytosis has never been examined in GBM cells. In the present study, we showed that gefitinib and other tyrosine kinase inhibitors induced EGFR accumulation in early-endosomes as a result of an increased endocytosis. Moreover, TKIs trigger early-endosome re-localization of another membrane receptor, the fibronectin receptor alpha5beta1 integrin, a promising therapeutic target in GBM that regulates physiological EGFR endocytosis and recycling in cancer cells. Super-resolution dSTORM imaging showed a close-proximity between beta1 integrin and EGFR in intracellular membrane compartments of gefitinib-treated cells, suggesting their potential interaction. Interestingly, integrin depletion delayed gefitinib-mediated EGFR endocytosis. Co-endocytosis of EGFR and alpha5beta1 integrin may alter glioma cell response to gefitinib. Using an in vitro model of glioma cell dissemination from spheroid, we showed that alpha5 integrin-depleted cells were more sensitive to TKIs than alpha5-expressing cells. This work provides evidence for the first time that EGFR TKIs can trigger massive EGFR and alpha5beta1 integrin co-endocytosis, which may modulate glioma cell invasiveness under therapeutic treatment.