Department of Medicine I, Medical University of Vienna, Institute of Cancer Research and Comprehensive Cancer Center, Vienna, Austria.
Research Cluster "Translational Cancer Therapy Research", University of Vienna, Vienna, Austria.
Int J Cancer. 2020 Sep 15;147(6):1680-1693. doi: 10.1002/ijc.32924. Epub 2020 Mar 2.
Ponatinib is a small molecule multi-tyrosine kinase inhibitor clinically approved for anticancer therapy. Molecular mechanisms by which cancer cells develop resistance against ponatinib are currently poorly understood. Likewise, intracellular drug dynamics, as well as potential microenvironmental factors affecting the activity of this compound are unknown. Cell/molecular biological and analytical chemistry methods were applied to investigate uptake kinetics/subcellular distribution, the role of lipid droplets (LDs) and lipoid microenvironment compartments in responsiveness of FGFR1-driven lung cancer cells toward ponatinib. Selection of lung cancer cells for acquired ponatinib resistance resulted in elevated intracellular lipid levels. Uncovering intrinsic ponatinib fluorescence enabled dissection of drug uptake/retention kinetics in vitro as well as in mouse tissue cryosections, and revealed selective drug accumulation in LDs of cancer cells. Pharmacological LD upmodulation or downmodulation indicated that the extent of LD formation and consequent ponatinib incorporation negatively correlated with anticancer drug efficacy. Co-culturing with adipocytes decreased ponatinib levels and fostered survival of cancer cells. Ponatinib-selected cancer cells exhibited increased LD levels and enhanced ponatinib deposition into this organelle. Our findings demonstrate intracellular deposition of the clinically approved anticancer compound ponatinib into LDs. Furthermore, increased LD biogenesis was identified as adaptive cancer cell-defense mechanism via direct drug scavenging. Together, this suggests that LDs represent an underestimated organelle influencing intracellular pharmacokinetics and activity of anticancer tyrosine kinase inhibitors. Targeting LD integrity might constitute a strategy to enhance the activity not only of ponatinib, but also other clinically approved, lipophilic anticancer therapeutics.
泊那替尼是一种小分子多酪氨酸激酶抑制剂，临床上已批准用于癌症治疗。目前，癌症细胞对泊那替尼产生耐药性的分子机制还知之甚少。同样，细胞内药物动力学以及影响该化合物活性的潜在微环境因素也未知。应用细胞/分子生物学和分析化学方法研究了 FGFR1 驱动的肺癌细胞对泊那替尼的摄取动力学/亚细胞分布、脂滴（LDs）和类脂微环境在其中的作用。对获得性泊那替尼耐药的肺癌细胞进行选择，导致细胞内脂质水平升高。揭示泊那替尼的固有荧光，使我们能够在体外和小鼠组织冷冻切片中剖析药物摄取/保留动力学，并揭示了药物在癌细胞 LD 中的选择性积累。药理学 LD 上调或下调表明 LD 形成的程度和随之而来的泊那替尼掺入与抗癌药物疗效呈负相关。与脂肪细胞共培养会降低泊那替尼水平并促进癌细胞存活。经泊那替尼选择的癌细胞表现出 LD 水平升高，并增强了该细胞器中泊那替尼的沉积。我们的研究结果表明，临床上批准的抗癌化合物泊那替尼被沉积到 LD 中。此外，增加 LD 的生物发生被确定为通过直接药物清除来增强癌细胞防御的适应性机制。综上所述，这表明 LD 是一种被低估的细胞器，影响着抗癌酪氨酸激酶抑制剂的细胞内药代动力学和活性。靶向 LD 完整性可能是增强不仅是泊那替尼，还有其他临床上批准的亲脂性抗癌治疗药物活性的策略。
