Interrelationships between Cellular Nucleotide Excision Repair, Cisplatin Cytotoxicity, HER‐2/neu Gene Expression, and Epidermal Growth Factor Receptor Level in Non‐small Cell Lung Cancer Cells

Nucleotide excision repair (NER) is a major repair mechanism for DNA lesions induced by cisplatin. Overexpressions of epidermal growth factor receptor (EGFR) and HER‐2/neu have been reported to affect the sensitivity of certain human cancer cells to cisplatin, presumably by modification of DNA repair activity through interference with NER. Using an in vitro repair assay, we investigated NER activity of cisplatin‐induced DNA lesions in a panel of 16 non‐small cell lung cancer (NSCLC) cell lines. The interrelationships between NER activity, cisplatin sensitivity, HER‐2/neu expression and EGFR level, were also analyzed. The results showed that high NER activity was closely correlated with cisplatin resistance and high levels of HER‐2/neu expression (P < 0.05). Analysis of the relationships between EGFR level and each of the other three parameters revealed no statistically significant correlations (all P values were > 0.05 by Spearman rank correlation), but a trend of association (all the values of proportion of accordance were ≥62.5% by using a 2x2 contingency table). These results suggest that NER activity may play an important role in the cisplatin resistance of NSCLC cells and there may be an association between enhanced NER activity and high levels of p185(neu) and probably EGFR in NSCLC cells. The finding that high levels of EGFR showed very little influence on the relationship between p185(neu) and cisplatin resistance suggests that EGFR may be a less crucial factor in modulating the chemoresistance of NSCLC cells when compared with HER‐2/neu.