Expression and clinical significance of CRABP1 and CRABP2 in non-small cell lung cancer

The impairment of retinoic acid (RA)-dependent signaling is a frequent event during carcinogenesis. Cellular retinoic acid-binding proteins (CRABP1 and CRABP2) are important modulators of RA activity. Up to date, the role of these proteins in cancer progression remains poorly investigated. Here, we studied for the first time the simultaneous messenger RNA (mRNA) and protein expression of CRABPs in non-small cell lung cancer (NSCLC) samples. CRABP1 and CRABP2 mRNA levels were elevated in 42 and 56 % of NSCLC samples, respectively. Decrease of CRABP2 mRNA expression was significantly associated with the presence of lymph node metastases. Protein expression of CRABP1 and CRABP2 was detected in 50 and 56 % of tumor samples, respectively. We also found a positive correlation between CRABP1 and CRABP2 expression. Taken together, we demonstrated significant changes in CRABP expression in NSCLC samples. Importantly, the presented data provide the first evidence of potential involvement of CRABP2 in lung cancer metastasis.