Background
The small GTPases are involved in the regulation of critical cellular functions, such as transcription control, cell cycle, and organization of actin cytoskeleton. Although a number of investigations have established the significance of Rho-family GTPases in several human tumors, there is still little information available on the clinical significance of Rac1 expression in non-small cell lung cancer (NSCLC). Therefore, immunohistologic expression of Rac1 was studied in a tissue microarray of 111 Stage I-II NSCLCs and correlated with clinicopathologic parameters and clinical outcome.
Material and Method
For this retrospective study 111 tissue samples, obtained from anonymized patients with early operable NSCLC (stage I-II), were used to construct a tissue microarray for immunohistochemical study.
Results
Rac1 showed a cytoplasmic pattern of expression in tumor cells, while normal lung components showed negative or weak cytoplasmic staining. Rac1 expression increased significantly with the advancement of the T stage (P<0.01) and the TNM stage (P<0.05). Analysis of overall survival showed that Rac1 expression was related to poor outcome (P=0.012), even in the group of stage I patients (P=0.023). Multivariate analysis showed that Rac1 overexpression was an independent marker for overall survival after adjusting for other prognostic factors (P=0.023).
Conclusions
We found a positive prognostic value of immunohistologically determined Rac1 protein expression and presents Rac1 as a potential unfavorable prognosis biomarker in patients with early operable NSCLC.

Keywords: Proportional Hazards Models, Lung Neoplasms - surgery, Carcinoma, Non-Small-Cell Lung - surgery, rac1 GTP-Binding Protein - metabolism