The recently discovered rTS gene is convergent with and overlaps the thymidylate synthase gene in the antisense orientation. K562 B1A and KB 1BT are two methotrexate-resistant cell lines that have amplified genes for dihydrofolate reductase. K562 B1A cells have increased levels of rTS mRNA and protein compared with their parental K562 cells, whereas KB 1BT cells show unaltered rTS expression co...

We previously reported that MX2, a new morpholino anthracycline, showed marked effects on pleiotropic drug-resistant sublines of murine P388 leukemia in vivo as well as in vitro. In this study we examine the in vitro cytotoxicity against pleiotropic drug-resistant sublines of human tumor cell lines. MX2 was effective against multidrug-resistant sublines of four human tumor cell lines; these cel...

Previously, we characterized a zinc finger protein gene HZF1 (ZNF16) and demonstrated that it played a significant role in the erythroid and megakaryocytic differentiation of K562 cells by knockdown of the gene. In this study, we examined the effect of HZF1 on the proliferation and apoptosis of K562 cells and identified the possible mechanism for this effect. By lentivirus-mediated gene transfe...

Resistance to imatinib is commonly associated with reactivation of Bcr-Abl signalling. However, Bcr-Abl-independent signalling pathways may be activated and contributed to imatinib resistance in some CML (chronic myelogenous leukaemia) patients. We had isolated three imatinib-resistant K562/R1, R2 and R3 variants with gradual loss of Bcr-Abl from K562 cells to develop effective therapeutic stra...

We have investigated the hormonal responsiveness of K562 cells using a serum-substituted in vitro clonogenic assay. Dexamethasone inhibited colony formation by the K562 cells. and the inhibitory effect could be reversed by progesterone (10 M). Fluoxymesterone caused a prominent enhancement of K562 colony growth. whereas estriol had no effect. Stimulation by triiodothyronine was maximal at iO M....

Asciminib (previously ABL001), which binds the myristate-binding pocket of the Bcr-Abl kinase domain, is in phase I clinical trials as monotherapy and in combination with imatinib, nilotinib and dasatinib for the treatment of patients with refractory CML or Ph+ ALL. Asciminib sensitivity was evaluated in asciminib naïve BCR-ABL1+ cell lines K562 (negligible ABCB1/ABCG2 expression), K562-Dox (AB...

We previously reported that natural killer (NK)-sensitive target cells, K562, kill interleukin-2-stimulated (lymphokine-activated killer [LAK]) but not unstimulated NK cells. We have now investigated the molecular basis of this phenomenon. Soluble monoclonal antibody (MoAb) to CD18 inhibited 75% of K562-induced DNA fragmentation and membrane disruption, whereas blocking MoAb to Fas partially in...