  Background and Purpose: Colorectal cancer as a leading cause of mortality
worldwide, can be regarded as a relatively common and fatal disease with
increasing incidence over recent years. Colorectal cancer is characterized by
uncontrolled growth of abnormal cells occurring in different parts of the
colon. About 90% of deaths associated with cancers occur due to metastasis
which overcome overcomes the body's cellular connection, including tight
junctions. Claudin and Occludin are integral membrane proteins found in tight
junctions. The aim of the present study was to investigate the expression level
of claudin and occludin in human colorectal cancer. Method: In this study, 38
colorectal cancer patients who referred to Cancer Institute of Imam Khomeini
Hospital in Tehran, Iran were studied after obtaining the informed consent.
First, quantitative extraction of RNA was performed, then the expression levels
of claudin and Occludin genes were examined by reverse transcription, PCR, and
Real-time PCR. Findings: The expression levels of both claudin and Occludin
genes in cases with higher stage and grade of disease, in the state of
metastasis were more than those of the control samples. Conclusion: The
increased expression level of the mentioned genes can be considered as an
influential factor in turning the normal healthy tissues into cancerous cells.
