BACKGROUNDTo study the abnormal expression of β-catenin and its mRNA in non-small-cell lung cancer (NSCLC) and its relation to histological classification and cell differentiation.

METHODSThirty-five cases of NSCLC (18 squamous cell carcinomas and 17 adenocarcinomas ) and eight adjacent para-cancerous tissues were obtained from September 2002 to March 2003 and diagnosed pathologically. Immunofluorescence and confocal microscope were used to investigate the distribution of β-catenin. By using the staining of normal cell membrane as a positive control, the staining of tumor cell membrane was divided into two categories, fifty percent or more of tumor cell membranes stained positive and less than fifty percent of tumor cell membranes stained positive. If the image contained one or more cells stained in nuclei or/and cytoplasmic, the image was scored positive. The mRNA expression of β-catenin was detected by one-step RT-PCR. The integrated density values of PCR productions were analyzed semiquantitatively.

RESULTSImmunofluorescence showed that the membranous expression of β-catenin reduced in the thirty-seven percent of NSCLC (13/35). Furthermore, the membranous expression was significantly more heterogeneous in tumors than that in normal tissues. There was no significant difference among the β-catenin expression, histological classification and cell differentiation of the cancer. β-catenin accumulated in the one-hundred percent of the cytoplasm and the fifty-one percent of the nuclei. The mRNA expression of β-catenin in squamous cell carcinoma (0.280±0.136) and adenocarcinoma ( 0.260 ±0.086) was remarkably higher than that in the para-cancerous tissues (0.120±0.069, P < 0.01).There was no significant difference of β-catenin mRNA expression in histological classification and cell differentiation.

CONCLUSIONSAbnormal subcellular distribution and deletion of mRNA expression of β-catenin may play an important role in the oncogenesis and progression of NSCLC.