Presence of Autoantibodies against Ras-like GTPases in Serum in Stage I/II Breast Cancer

Original Article
Background: Ras-like GTPases, RalA, and RalB, are members of the Ras superfamily of small GTPases. Their aberrant activation is a major cause of human tumorigenesis induced by oncogenic Ras. Serum anti-RalA antibodies (s-RalA-Abs) are induced in patients with esophageal carcinoma, but there have been no reports regarding their presence in patients with breast cancer. Methods: Serum samples from 100 patients with breast cancer and 73 healthy individuals were analyzed using an enzyme-linked immunosorbent assay system specifically developed for s-RalA-Abs. Positive rates of s-RalA-Abs and serum p53 antibodies (s-p53-Abs) were evaluated for two cut-off optical density values of 0.26 and 0.33 (i.e., the control mean+2 and 3 standard deviations), respectively. Results: Overall positive rates for s-RalA-Abs at the two cut-offs were 24% and 11%, respectively, with no statistically significant differences between stage I and stage II cancers. The positive rate increased significantly in a combination assay of s-p53-Abs with s-RalA-Abs, and s-RalA-Abs was shown to be inversely associated with s-p53-Abs. Conclusions: s-RalA-Abs in combination with s-p53-Abs may be a candidate serum antibody marker for breast cancer.