Sonic hedgehog (Shh) processing in gastric cancer cells is dependent on the activation of pepsinogen

Objective Sonic hedgehog (Shh) is highly expressed in parietal cells and is thought to regulate epithelial cell differentiation in the stomach. We have recently observed that Shh is processed from its full‐length 45kDa precursor to the biologically active 19kDa peptide through the activation of pepsinogen (PG) I. Interestingly, reduced serum PGI levels and Shh expression is correlated with atrophic gastritis and increased risk of gastric cancer. Thus, the present study investigates whether carcinogenesis alters Shh processing based on changes in PG expression. Methods Protein was extracted from human gastric cancer cell lines (AGS, MKN, NCI‐N87, 23132/87). Media from these cell lines was collected, concentrated and purified using gel filtration chromatography. Whole cell extracts (WCE) from AGS, MKN, NCI‐N87 and 23132/87 cell lines were prepared and incubated with in vitro translated Shh peptide (pH2‐3). Shh protein expression and processing was analyzed by western blot. Immunofluorescence for PG I and the parietal cell marker H + ,K + ‐ATPase on the gastric cancer cell lines was performed. Results Nascent 45kDa Shh protein was expressed in MKN, NCI‐N87 and 23132/87 but not in AGS cells. The processed 19kDa Shh peptide was secreted from 23132/87 cells alone. Processing of the in vitro translated Shh 45kDa to 19kDa peptide was observed using WCE from 23132/87 cells alone. Immunofluorescence revealed PGI staining in all cell lines except AGS cells. The 23132/87 cell line alone expressed H + ,K + ‐ATPase. Conclusion Shh processing was shown in at least one gastric cancer cell line (23132/87) that also expressed PGI and H + ,K + ‐ATPase. Therefore, expression of PGI and H + ,K + ‐ATPase may impart valuable information about the different clinical behaviors of tumor cells.