OBJECTIVETo screen genes differentially expressed in two human giant-cell lung cancer lines of same origin but with different metastasis potentials.

METHODSSuppression subtractive hybridization (SSH) was done twice on two giant-cell lung cancer lines, PLA-801C and PLA-801D (hereafter abbreviated as C and D), of same origin but with low (C) and high (D) metastatic potentials. In the first round, SSH C was used as tester and D as driver, while in the second round, the tester and driver were interchanged. The sequences acquired from both rounds of SSH were spotted on glass slides respectively and screened by hybridizing with two-color fluorescence probes. Clones that had different expression levels on chips were also confirmed by RNA dot blot or Northern blot.

RESULTSThere were 16 sequences with high expression in C as compared to those in D, and 79 sequences with high expression in D compared to those in C. After sequencing, most of them were found to be highly homologous to those encoding the following proteins: (1) cytokines and their receptors; (2) kinases and related proteins; (3) other proteins including enzymes, heat shock proteins, receptors, proteins of cell skeleton and mitochondria, products of oncogenes, etc; (4) some proteins deduced from gene sequences with yet unknown functions.

CONCLUSIONThe alterations in expression of some known genes, including HSP70, AXL receptor tyrosine kinase and 14-3-3zeta, might have impact on metastasis of giant-cell lung cancer. Whether some differentially expressed genes newly revealed are metastasis-related needs further study.