Supplementary Material for: Distinct Involvement of the Sonic Hedgehog Signaling Pathway in Gastric Adenocarcinoma of Fundic Gland Type and Conventional Gastric Adenocarcinoma

Background/Aims: Gastric adenocarcinoma of fundic gland
type (GAFG), which is a rare variant of gastric cancer, is reportedly
associated with both Wnt/β-catenin signaling activation and guanine
nucleotide binding protein, alpha stimulating complex (GNAS) mutations. This study aimed to elucidate potential roles of the Sonic hedgehog (Shh) signaling pathway in GAFG. Methods:
We performed immunostaining for β-catenin and Shh signal-associated
proteins, including Patched (Ptch), Smoothened (Smo), and
Glioma-associated oncogene-1 (Gli1), and the direct sequencing of GNAS/BRAF/KRAS in 27 GAFGs, and compared them with 30 conventional gastric adenocarcinomas (CGAs). Results:
GAFGs exhibited significantly lower immunoreactivity scores for Ptch,
Smo, and Gli1 than CGAs. Moreover, while the Ptch score was
significantly lower in the GAFG tumor areas than in the non-neoplastic
areas adjacent to GAFG, the score was significantly higher in the CGA
tumor areas than in the non-neoplastic areas. Similar trends were
observed in the scores for Smo and Gli1. β-Catenin expression and GNAS
mutations were found in 22 (81%) and 8 (30%) of the 27 GAFGs
respectively. Gli1 expression was significantly associated with
mutations in GNAS. Conclusion: GAFG and CGA
exhibited distinct Ptch, Smo, and Gli1 expression patterns.
Downregulation of the Shh signaling pathway, as well as activation of
the Wnt/β-catenin signaling pathway, may therefore be associated with
tumorigenesis in GAFG.