Identification of serum anti-striatin 4 antibodies as a common marker for esophageal cancer and other solid cancers.

Solid cancers have a poor prognosis, and their morbidity and mortality after surgery is high. Even after radical surgery for esophageal cancer, there have been cases of early postoperative death. The present study therefore aimed to explore new tumor markers that can predict the early postoperative prognosis. To identify antibody markers, serological antigens were identified using recombinant cDNA expression cloning (SEREX). The results identified striatin 4 (STRN4) as the antigen recognized by serum IgG antibodies in patients with esophageal cancer. After performing an amplified luminescence proximity homogeneous assay-linked immunosorbent assay (AlphaLISA), it was revealed that when compared with healthy donors, serum anti-STRN4 antibody (STRN4-Ab) levels were significantly higher not only in patients with esophageal cancer but also to lesser extent, in those with gastric cancer, colorectal cancer, lung cancer and breast cancer. Compared with STRN4-Ab-negative patients with esophageal cancer, STRN4-Ab-positive patients had a poorer postoperative prognosis at early stages, suggesting that STRN4-Abs may be useful for predicting poor early-stage prognoses of patients with esophageal cancer. The positive diagnosis rates of esophageal cancer using the STRN4-Ab marker and conventional markers, including squamous cell carcinoma antigen and p53 antibody alone, were 26.4, 35.2 and 19.1% respectively; a result that increased up to 59.1% by combining all three markers. Serum STRN4-Ab may serve as a novel marker of esophageal cancer.