Objective     To obtain the expression pattern of multidrug resistance-associated gene in human small cell lung cancer (SCLC) MDR cell line SH77/CDDP and provide basis for further studying the mechanism of human SCLC MDR induced by cisplatin.      Methods     Total RNA was isolated from SCLC MDR cell line SH77/CDDP and its parental cells

and synthesized into double-stranded cDNA

then synthesized into biotin-labeled cRNA probe by in vitro transcription. The cRNA probes were separately hybridized with Affymetrix GeneChip and human U133 set chips (U133A and U133B

containing 39 000 transcripts

including 33 000 known human genes and 6 000 unknown cDNA expression sequence tags

ESTs)

and the signals were scanned by the GeneArray Scanner. The results were analyzed by bioinformatics.      Results     Compared with the gene expression profile of parental SH77 cells

2 389(6.13%) genes were up-regulated in SCLC MDR cell line SH77/CDDP cells

of which 461 (1.19%)

89 (0.23%)

26 (0.07%) and 7 (0.02%) genes were separately up-regulated one-fold

two-folds

three-folds and four-folds.36 genes

including ABCC3

HSP70

CYP26B1

CYP4A11

IGF1R

LOX2

CAP2

LRP2BP

AKNA

ELTD1 and otherwise，were up-regulated 2.5-5.1 folds. According to Gene Ontology and Tree View analysis

these 35 genes were involved in transport

cell adhesion

signal transduction

transcription and ion binding and so on.      Conclusion     Many multidrug resistance-associated genes induced by cisplatin have been screened by high-throughput gene chip method. Validating their cellular functions will help to identify the mechanism of human SCLC MDR induced by cisplatin.