Microarray analysis of responsible genes in increased growth rate in the subline of HL60 (HL60RG) cells

HL60RG, a subline of human promyelocytic leukemia HL60 cells, has a increased growth rate than their parental cells. To gain information of the mechanisms involved in the increased growth rate of HL60RG, we performed a multiplex fluorescence in situ hybridization (M-FISH), standard cytogenetics analysis (G-banding) and genome scan using 10K SNP mapping array on both cell types. Characteristic genomic alterations in HL60RG cells were identified including uniparental disomy (UPD) of chromosome 1, and hemizygous deletion in 10p and 11p. However, no such defects were observed in HL60 cells. Changes in gene expression in HL60RG cells were determined using expression arrays (Affymetrix GeneChip, HU133A). Candidate genes associated with the rapid growth of HL60RG cells were identified. Two tumor necrosis factor receptors, TNFRSF1B (type II tumor necrosis factor-α receptor) and TNFRSF8 (also known as a tumor marker CD30), which are adjacently located on chromosome 1 showed opposing changes in gene expression in HL60RG cells-over-expression of TNFRSF8 and repression of TNFRSF1B. Differences in the DNA methylation status in the transcriptional regulatory regions of both genes between HL60 and HL60RG was detected by a methylation-specific PCR assay. In conclusion, alterations in chromosome and gene expression in HL60RG may be associated with increased growth rate.