Sonic Hedgehog Protein Purification and Identification: A Potential Biomarker for Pancreatic Cancer
Cantú, Esperanza Felicidad
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New insights into the molecular biology of pancreatic cancer may help to improve patient survival. Sonic hedgehog (Shh) protein is misexpressed and may maintain tumor growth in pancreatic cancer. The digestive system served as a model to study Hedgehog (Hh) signaling, and it was found that Shh might be secreted from the stomach into the blood. Shh can be secreted from basolateral membranes of parietal cells into the mesenchymal tissue, which contains blood capillaries. Shh transport through the blood suggests that Shh could be traveling from the stomach to the pancreas, possibly maintaining cancer cells. The aims of this study were to identify plasma Shh, and determine a correlation between plasma Shh concentration and pancreatic cancer. It was hypothesized that because Shh is upregulated in pancreatic cancer tissue, plasma Shh concentration might reflect the same trend. Shh was identified in blood plasma using a Human Shh ELISA. To purify the plasma and identify Shh protein via SDS-PAGE, fast protein liquid chromatography, agarose bead immunoprecipitation, and heparin affinity chromatography were employed. Pancreatic cancer patients had significantly lower plasma Shh concentration in comparison to healthy patients. Moreover, Shh plasma concentration as a biomarker yielded a 95.9% negative predictive value. This indicates a high probability that screening Shh plasma concentration would correctly diagnose patients without pancreatic cancer. Mass spectrometry analysis of an SDS-PAGE gel displaying a 19-kDa-protein band revealed that Shh could not be detected; however, it is possible that another Hh protein could be detected. The study should be repeated with different fractions of the blood obtained through FPLC, and with age-matched controls to eliminate the superficial result that age predicts pancreatic cancer.