Deletion in HSP110 T17: correlation with wild-type HSP110 expression and prognostic significance in microsatellite-unstable advanced gastric cancers.

Deletion of the HSP110 T17 mononucleotide repeat has recently been identified as a prognostic marker that is correlated with wild-type HSP110 (HSP110wt) expression in microsatellite instability-high (MSI-H) colorectal cancers. The aim of this study was to assess the correlation between deletion of the HSP110 T17 repeat and expression of HSP110wt using DNA testing and immunohistochemistry and to determine the prognostic implications of HSP110 T17 deletion in MSI-H advanced gastric cancers (GCs). The status of HSP110wt expression was evaluated by immunohistochemistry using an HSP110wt-specific antibody in 142 MSI-H advanced GCs. The size of the HSP110 T17 repeat deletion was analyzed in 96 MSI-H advanced GCs; deletions were divided into small (0-2base pairs) and large deletions (3-5base pairs). Low and high expressions of HSP110wt were detected in 38 (26.8%) and 104 (73.2%) of the 142 cases, respectively. The HSP110 T17 deletion was observed in 45 (46.9%) of the 96 MSI-H GC samples. Tumors with high expression of HSP110wt showed a tendency to have small or no deletion of HSP110 T17. In Kaplan-Meier survival analysis, tumors with a large HSP110 T17 deletion were associated with favorable overall survival and disease-free survival compared with those with small/no deletion of HSP110 T17. However, HSP110 T17 deletion size was not an independent prognostic factor in multivariate analysis. In summary, deletion of the HSP110 T17 repeat was frequently observed in MSI-H GCs, and HSP110 T17 deletion size was inversely correlated with HSP110wt expression status. Large HSP110 T17 was not a prognostic indicator in MSI-H GCs.