ErbB3 mRNA expression correlated with specific clinicopathologic features of Japanese lung cancers

ErbB3 is a member of the epidermal growth factor receptor (EGFR) family of tyrosine kinase. A previous report has suggested that overexpression of ErbB3 protein was associated with lung cancer recurrence. Other reports suggested that high ErbB3 protein expression was associated with shorter survival in advanced non-small-cell lung carcinomas (NSCLC). The relationship between the erbB3 mRNA expression and EGFR mutation has not been reported. In this study, we have investigated the erbB3 mRNA levels in reference to clinicopathologic data and EGFR mutation status in Japanese lung cancer specimens.

This study included 192 surgically removed NSCLC cases operated at Nagoya City University Hospital. The erbB3 mRNA levels were quantified by real-time polymerase chain reaction using LightCycler (Roche Molecular Biochemicals, Mannheim, Germany).

The erbB3/glyceraldehydes-3-phosphatate dehydrogenase levels were significantly higher in female than in male (P < 0.0001), higher in nonsmoker than in smoker (P = 0.0007), higher in adenocarcinoma than in other types of lung cancers (P < 0.0001), and higher in well-differentiated than in less-differentiated subtypes (P = 0.0304). The erbB3/glyceraldehydes-3-phosphatate dehydrogenase levels were significantly higher in patients with EGFR gene mutation than in patients without mutation (P = 0.0124).

The present study suggests that increased expression of erbB3 may play an additional role in NSCLC especially in female, nonsmoker, adenocarcinoma, and with EGFR gene mutation. Further studies on large sample sizes would help to determine if erbB3 expression is a clinically useful tool to further define patients who will benefit from EGFR TKIs.