Background & objectives: KAI1 is a tumor suppressor gene and inhibitor of metastasis in a wide range of malignancies. While it is ubiquitously expressed in normal tissues, KAI1 expression subjects to the down regulation in tumors. The present research aims semi-quantitative evaluation of KAI1 mRNA expression in Iranian patients with colorectal cancer (CRC) and correlation between expression levels of KAI1 and stage oftumorigenesis, especially metastasis and invasion of CRC as well as pathologic factors of patients.

Methods: RT-PCR was done by specific primers for KAI1 and β-actin genes on the 80 tumor tissues and 14 normal tissues as fresh samples which obtained from 80 unrelated patients referred to Imam Khomeini Hospital.  

Results: According the results, 51.2% and 48.8% of the sample were on and off for KAI1 gene expression, respectively. As a detail, 97.3% of samples in the stage 3 and 4 and 94.5% of metastatic phases samples showed no expression of this gene. Statistical analysis showed that there is a significant difference of the KAI1 expression between four groups of samples; normal, stage 1, 2 and 3 (p<0.05). Also a significant difference was observed between semi-quantitative KAI1 expression and degree of spread to regional lymph nodes (p=0.02) as well as semi-quantitative KAI1 expression and metastasis (p=0.000001).

Conclusion: A significant difference between semi-quantitative expression of KAI1 and degree of spread to regional lymph nodes (p=0.02) and metastasis (p=0.000001) was observed.