Methotrexate (MTX)-resistant K562 human myclocytic leukemia sublines with 20- and 200-fold amplified dihydrofolate reductase (DHFR) genes localized to homogeneously staining regions (HSRs) on the long arms of chromosomes 5, 6, and 19 were used to examine whether other genes mapping close to the DHFR genes were coamplified. The gene for 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, located on chromosome 5q13.3-14, was coamplified 4-14-fold, corresponding to the levels of resistance exhibited by these cells. Similar observations were made with a MTX-resistant subline of the promyelocytic leukemia cell line, HL-60R, with 200 gene copies of DHFR. These observations indicate a light linkage of DHFR and HMG-CoA genes on chromosome 5q.
All Science Journal Classification (ASJC) codes
- Dihydrofolate reductase
- Myclocytic leukemia cell lines