Background: T cell factor-4 (TCF-4) plays an important role in development and carcinogenesis. Recently, the role of TCF-4 has been described in colon cancer and other cancers. However, whether TCF-4 plays a similar role in lung cancer is unknown. To answer this question, we studied the expression of TCF-4 protein and mRNA in non-small-cell lung cancer (NSCLC) and the relation of TCF-4 expression pattern to histological type and cell differentiation.
Methods: Tissue samples from sixty cases of pathologically diagnosed NSCLC and eight normal tissue samples were obtained between September 2001 and March 2003. Immunohistochemistry was used to investigate the distribution of TCF-4 protein. The staining patterns of the tumors were divided into 4 categories: nuclear staining alone or nuclear staining greater than cytoplasmic staining; cytoplasmic staining or cytoplasmic staining greater than nuclear staining; equal nuclear and cytoplasmic staining; no nuclear staining or cytoplasmic staining. The integrated optical density (OD) values of all sections were analyzed by UIC MetaMorph image analysis software. The expression of TCF-4 mRNA was detected by one-step reverse transcription-polymerase chain reaction (RT-PCR). The integrated density values of the PCR products were analyzed semi-quantitatively.
Results: Immunohistochemistry showed that there was no expression of TCF-4 in normal tissue. However, TCF-4 was expressed in 86.7% (52/60) of NSCLC samples, mainly in the nuclei of tumor cells. Furthermore, there was a significant difference in TCF-4 localization patterns between squamous cell carcinomas and adenocarcinomas (P < 0.05). The integrated OD values of TCF-4 expression was significantly higher in tumors with moderate-poor cell differentiation than in well differentiated tumors (51.63 +/- 6.67 vs 46.13 +/- 12.31, P < 0.01). There was no TCF-4 mRNA expression in normal tissue. However, 63.9% (23/36) of carcinoma samples expressed TCF-4 mRNA. TCF-4 mRNA expression was significantly higher in tumors with moderate-poor cell differentiation than in well differentiated tumors (P < 0.05). There were no significant differences in mRNA expression in comparison with histological type.
Conclusions: The sub-cellular distribution of TCF-4 may correlate with NSCLC histological type. High expression of TCF-4 mRNA and protein may be associated with the degree of cell differentiation in NSCLC.