a b s t r a c tSodium glucose cotransporters (SGLT) actively catalyse carbohydrate transport across cellular membranes. Six of the 12 known SGLT family members have the capacity to bind and/or transport monosaccharides (SGLT-1 to 6); of these, all but SGLT-5 have been characterised. Here we demonstrate that human SGLT-5 is exclusively expressed in the kidney. Four splice variants were detected and the most abundant SGLT-5-mRNA was functionally characterised. SGLT-5 mediates sodium-dependent [ 14 C]-a-methyl-D-glucose (AMG) transport that can be inhibited by mannose, fructose, glucose, and galactose. Uptake studies using demonstrated high capacity transport for mannose and fructose and, to a lesser extent, glucose, AMG, and galactose. SGLT-5 mediated mannose, fructose and AMG transport was weakly (lM potency) inhibited by SGLT-2 inhibitors. In summary, we have characterised SGLT-5 as a kidney mannose transporter. Further studies are warranted to explore the physiological role of SGLT-5.

High-resolution melting provides a valid and powerful tool for detecting genomic mutations efficiently.

The accuracy of common markers for PI3K/AKT and MAPK pathway activation in preclinical and clinical cancer biomarker studies depends on phosphoepitope stability and changes of phosphorylation under ischemia. Herein, we define conditions under which phosphoepitope-specific duplex immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded tumor tissues reflects pathway activation in situ as accurately as possible, and identify activation patterns linked to mutational status, pathway dependency and tumor microenvironment in clinical tumor samples, cell culture and xenograft tissues. Systematically assessing robustness of pAKT, pERK1/2, pMEK1/2 and pmTOR detection and related markers in xenograft tissues exposed to ischemia, we show that control of preprocessing and ischemia times allows accurate interpretation of staining results. Phosphorylation patterns were then analyzed in 33 xenograft models and in 58 cases with breast cancer, including 21 paired samples of core-needle biopsies with corresponding mastectomy specimens, and 37 mastectomy samples obtained under rigorously controlled conditions minimizing ischemia time. Patterns of pAKT and pERK1/2 staining (predominant PI3K/AKT, predominant MAPK and concomitant activation) were associated with sensitivity to pathway inhibition and partially with the mutational status in cell lines and corresponding xenograft tumors. In contrast, no clear correlation between mutational status and staining patterns was observed in clinical breast cancer samples, suggesting that interaction with the human tumor microenvironment may interfere with the use of phosphoepitope-specific IHC as potential markers for pathway dependency. In contrast to core needle biopsies, surgically resected breast cancer samples showed evidence of severe signal changes comparable to those effects observed in xenograft tumors exposed to controlled ischemia.Robust assessment of kinase phosphorylation in tumor biopsy samples is necessary to understand how mutations translate into aberrant oncogenic signaling, and it has been successfully used as pharmacodynamic marker to monitor the effect of therapeutic inhibition of cancer-related pathways.