Here we tested the efficacy of inhibiting cyclin-dependent kinase 9 (CDK9) on lung cancer cell lines with K-Ras and EGFR mutations and on lung cancer organoids

Here we tested the efficacy of inhibiting cyclin-dependent kinase 9 (CDK9) on lung cancer cell lines with K-Ras and EGFR mutations and on lung cancer organoids. reduced the viability and anchorage-independent growth of lung cancer cell lines at very low nanomolar to micromolar concentrations. CDK9 inhibition suppressed the expression of the anti-apoptotic protein, Mcl1, as well as SAPK the embryonic stem cell transcription factors, Sox2 and Sox9, which are pro-tumorigenic. In contrast, treatment with CDK9 inhibitors increased the levels of WT p53 and its downstream target p21 in K-Ras mutant cell lines. Furthermore, the CDK9 inhibitors could markedly reduce the viability of Osimertinib-resistant PC9 and AMG510-resistant H23 and H358 cells with comparable efficacy as the parental cells. CDK9 inhibitors could also significantly reduce the growth and viability of lung cancer organoids with high potency. Taken together, the data presented here strongly suggest that CDK9 inhibitors would be efficacious against K-Ras mutant and EGFR mutant NSCLCs, including those that develop resistance to targeted therapies. and Q61R mutation by WES sequencing present, in both the original tumor and the tumor organoid. viability of the various cell lines was measured using MTT (3-(4, 5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide) assays [57,58]. A total of 2500 cells were cultured per well in 96-well plates in 100 L medium and treated with at least 10 different concentrations, ranging from 10 nM to 40 M of SNS032 and LY2857785, or 3 nM to 2 Coumarin M of AZD4573, alone or in combination with 0.5 M JQ1, for 72 or 96 h. Moreover, 10 L of MTT solution (5 mg/mL) was added to each well and plates were incubated for 2C4 h, the formazan crystals were solubilized in 100 L DMSO prior to measurement of absorbance at 570 nm and IC50 analysis was performed using GraphPad Prism software for graphing and statistics. Viability of the Organoids was conducted using the CellTiter-Glo luminescent cell viability assay kit from Promega (Madison, WI, USA). Organoids were dissociated (1000 cells/well in suspension) and were cultured for 48 h in ultralow attachment 96 well plates prior to treatment with the CDK9 inhibitors for 96 h. At the end of treatment, CellTiter-Glo reagent was added to the wells and viability was determined by measuring the luminescence on a 96-well formatted luminometer. for detection of apoptosis in cells treated with CDK9 inhibitors we used the FITC Annexin V apoptosis Coumarin detection kit with PI from BioLegend, following the manufacturers instructions. Briefly, A549, H1650, PC9 parent and osimertinib-resistant, and H23 parent and AMG510-resistant cells were plated into 8 chamber slides at a density of 15,000C20,000 cells/well. After 24 h cells were treated with 20 Coumarin nM AZD4573, 0.5 M JQ1 or a combination of AZD4573 and JQ1 for 24 h. Cells treated with DMSO served as control. At the end of the treatment cells were Coumarin washed twice with cell staining buffer and incubated with 100 L Annexin V/PI diluted in binding buffer for 15C30 min at room temperature, protected from light. Subsequently, 250 L of binding buffer was added to the wells and the cells were imaged immediately using an inverted EVOS fluorescent microscope at 20 magnification. cells cultured on 60-mm tissue culture dishes (2.5 105 cells/dish) were treated with 20 nM AZD4573 for the indicated times. At the end of the.