Differential Expression of IQGAP1/2 in Hepatocellular Carcinoma and its Relationship with Clinical Outcomes

Purpose: To investigate IQGAP1 and IQGAP2 expression in hepatocellular carcinoma (HCC) and itsassociation with HCC clinicopathological characteristics and survival outcomes.
Methods: IQGAP1 and IQGAP2 mRNA and protein were measured in HCC tissues, para-tumor tissues and normal tissues by RT-PCR and Western blotting. We further examined 150 HCC samples with adjacent para-tumor tissues and 11 normal specimens by immunohistochemistry to evaluate the correlation of IQGAP1 and IQGAP2 with clinicopathological features and prognosis.
Results: IQGAP1 mRNA and protein were up-regulated while IQGAP2 mRNA and protein were down-regulated in human HCC tissues compared with para-tumor and normal liver tissues (p<0.05). IQGAP1 expression was higher in primary HCC (122/150, 81.3%) than matched adjacent tissues (30/150, 20%, p<0.001), whereas IQGAP2 was lower (31/150, 20.7% as compared to 112/150, 74.7%, P<0.001). Positive IQGAP1 expression correlated with larger tumor size (p=0.002), advanced TNM stage (p=0.002) and tumor differentiation (Ⅲ and Ⅳ, p=0.034). Negative IQGAP2 expression was significantly associated with larger tumor size (p=0.009), multicentric tumor occurrence (p=0.01), advanced TNM stage (0.009) and tumor differentiation (Ⅲ and Ⅳ, p=0.020). Survival analysis revealed that patients with either IQGAP1+ or IQGAP2- tumors had significantly reduced disease-free survival (p<0.001 and 0.006 respectively) and overall survival (p<0.001 for both). Multivariate analysis showed that IQGAP1/2 switch was an independent prognosis factor for disease-free survival (HR=2.824) and overall survival (HR=2.189).
Conclusion: Positive IQGAP1 and negative IQGAP2 expression were closely correlated with tumor progression and could be used as adjunctive biomarkers to improve prognostication for HCC patients.