Peroxisome proliferator-activated receptor-α expression is associated with histological type in human gastric carcinoma

Gastric carcinoma is one of the most common types of cancer worldwide and a leading cause of cancer-related mortality. Gastric carcinoma is histologically subdivided into differentiated and undifferentiated carcinoma, with the latter including poorly differentiated carcinoma and signet ring cell carcinoma (SRCC). Poorly differentiated carcinoma and SRCC have a worse prognosis compared with differentiated carcinoma. Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors and the PPAR-alpha subtype regulates important cellular functions, including cell proliferation, energy metabolism, oxidative stress, immune responses and cell differentiation. The aim of the present study was to elucidate the associations between clinicopathological factors and PPAR-alpha expression in patients with gastric carcinoma. The immunohistochemical staining of specimens obtained from 57 patients showed that PPAR-alpha expression was slightly weaker in undifferentiated carcinoma than in differentiated carcinoma (P<0.01). PPAR-alpha expression also significantly differed between poorly differentiated carcinoma (both positive and negative: 14/20, 70%) and SRCC (not expressed: 0/7, 0%) (P<0.01). However, PPAR-alpha expression was not significantly affected by age, lymph node invasion, venous invasion, lymph node metastasis, depth of invasion or stage. Collectively, the present results demonstrated that the downregulated expression of PPAR-alpha may play a key role in the biological transformation of tumors. Therefore, PPAR-alpha appears to be an important protein related to histology and may hold promise as a prognostic marker. Further studies with a larger number of subjects are needed to elucidate the relationship between PPAR-alpha expression and tumor progression and to analyze long-term clinical survival.