Despite decreasing incidence and mortality, gastric cancer remains the second leading cause of cancer-related deaths in the world. Successful management of gastric cancer is hampered by lack of highly sensitive and specific biomarkers especially for early cancer detection. Cell surface proteins that are aberrantly expressed between normal and cancer cells are potentially useful for cancer imaging and therapy due to easy accessibility of these targets. Combining two-phase partition and isobaric tags for relative and absolute quantification methods, we compared the relative expression levels of membrane proteins between noncancer and gastric cancer cells. About 33% of the data set was found to be plasma membrane and associated proteins using this approach (compared to only 11% in whole cell analysis), several of which have never been previously implicated in gastric cancer. Upregulation of SLC3A2 in gastric cancer cells was validated by immunoblotting of a panel of 13 gastric cancer cell lines and immunohistochemistry on tissue microarrays comprising 85 matched pairs of normal and tumor tissues. Immunofluorescence and immunohistochemistry both confirmed the plasma membrane localization of SLC3A2 in gastric cancer cells. The data supported the notion that SLC3A2 is a potential biomarker that could be exploited for molecular imaging-based detection of gastric cancer.

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An analogue of acetildenafil was detected in an extract of pre-mixed bulk powder. To our knowledge, the powder was destined to be encapsulated and sold as a dietary supplement. The structure was identified by NMR, HR-ESI-MS, ESI-MSn and FTIR analyses. Owing to the inclusion of a hydroxyl group in acetildenafil, the detected compound was called 'hydroxyacetildenafil'. With increasing use of dietary supplements marketed for penile erectile dysfunction, the detection of analogues of sexual performance enhancers is important and timely.