High co-expression of Sp1 and HER-2 is correlated with poor prognosis of gastric cancer patients

• We assess co-expression of HER-2 and Sp1 in GC patients for the first time.
• Co-expression of HER-2 and Sp1 identified a subtype GC with poor prognoses.
• Co-expression of HER-2 and Sp1 is an independent prognostic factor.
• Inhibition of Sp1 could be a potential target for GC therapeutic intervention.

The aim of this study was to investigate co-expression of HER-2 and Sp1 in gastric cancer (GC) so as to determine whether these two proteins may be correlated with poor prognosis of GC patients. We examined the HER-2 overexpression and amplification and expression levels of Sp1 in 227 GC patients using immune-histochemical staining and fluorescence in situ hybridization. Data on clinicopathological features and relevant prognostic factors in these patients were analyzed. Of the 227 gastric cancer samples, 11.89% were positive for HER-2 overexpression/amplification under the new scoring system, and the frequency of negative, weak positive and strong positive expression of Sp1 was 14.98%, 48.01% and 37.0% respectively. No statistically positive correlation was observed between the expression levels of HER-2 and Sp1 in GC tissues. HER-2 overexpression was closely correlated to the Lauren type, degree of differentiation, tumor size and lymph node metastasis, and Sp1 as well (P < 0.05). Overexpression of HER-2 and Sp1 predicted poor survival in univariate analysis as well as in a Cox proportional hazards model.