Shukla Sanjeev, Fletcher Steven, Chauhan Jay, Chalfant Victor, Riveros Carlos, Mackeyev Yuri, Singh Pankaj Kumar, Krishnan Sunil, Osumi Teruko, Balaji K C
University of Florida, Department of Urology, Jacksonville, FL, 32209, USA.
Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, 21201, USA.
Cancer Gene Ther. 2022 Nov;29(11):1550-1557. doi: 10.1038/s41417-022-00455-4. Epub 2022 Apr 19.
The proto-oncogene cellular myelocytomatosis (c-Myc) is a transcription factor that is upregulated in several human cancers. Therapeutic targeting of c-Myc remains a challenge because of a disordered protein tertiary structure. The basic helical structure and zipper protein of c-Myc forms an obligate heterodimer with its partner MYC-associated factor X (MAX) to function as a transcription factor. An attractive strategy is to inhibit MYC/MAX dimerization to decrease c-Myc transcriptional function. Several methods have been described to inhibit MYC/MAX dimerization including small molecular inhibitors and proteomimetics. We studied the effect of a second-generation small molecular inhibitor 3JC48-3 on prostate cancer growth and viability. In our experimental studies, we found 3JC48-3 decreases prostate cancer cells' growth and viability in a dose-dependent fashion in vitro. We confirmed inhibition of MYC/MAX dimerization by 3JC48-3 using immunoprecipitation experiments. We have previously shown that the MYC/MAX heterodimer is a transcriptional repressor of a novel kinase protein kinase D1 (PrKD1). Treatment with 3JC48-3 upregulated PrKD1 expression and phosphorylation of known PrKD1 substrates: the threonine 120 (Thr-120) residue in beta-catenin and the serine 216 (Ser-216) in Cell Division Cycle 25 (CDC25C). The mining of gene expression in human metastatic prostate cancer samples demonstrated an inverse correlation between PrKD1 and c-Myc expression. Normal mice and mice with patient-derived prostate cancer xenografts (PDX) tolerated intraperitoneal injections of 3JC48-3 up to 100 mg/kg body weight without dose-limiting toxicity. Preliminary results in these PDX mouse models suggest that 3JC48-3 may be effective in decreasing the rate of tumor growth. In conclusion, our study demonstrates that 3JC48-3 is a potent MYC/MAX heterodimerization inhibitor that decreases prostate cancer growth and viability associated with upregulation of PrKD1 expression and kinase activity.
原癌基因细胞髓细胞瘤病蛋白（c-Myc）是一种转录因子，在多种人类癌症中表达上调。由于其蛋白质三级结构紊乱，对c-Myc进行治疗性靶向仍然是一项挑战。c-Myc的碱性螺旋-环-螺旋结构域和拉链蛋白与其伙伴MYC相关因子X（MAX）形成一个专性异源二聚体，作为转录因子发挥作用。一种有吸引力的策略是抑制MYC/MAX二聚化，以降低c-Myc的转录功能。已经描述了几种抑制MYC/MAX二聚化的方法，包括小分子抑制剂和蛋白质模拟物。我们研究了第二代小分子抑制剂3JC48-3对前列腺癌生长和活力的影响。在我们的实验研究中，我们发现3JC48-3在体外以剂量依赖性方式降低前列腺癌细胞的生长和活力。我们使用免疫沉淀实验证实了3JC48-3对MYC/MAX二聚化的抑制作用。我们之前已经表明，MYC/MAX异源二聚体是一种新型激酶蛋白激酶D1（PrKD1）的转录抑制因子。用3JC48-3处理可上调PrKD1的表达以及已知PrKD1底物的磷酸化：β-连环蛋白中的苏氨酸120（Thr-120）残基和细胞分裂周期蛋白25（CDC25C）中的丝氨酸216（Ser-216）。对人类转移性前列腺癌样本中的基因表达挖掘表明，PrKD1和c-Myc表达呈负相关。正常小鼠和患有患者来源的前列腺癌异种移植瘤（PDX）的小鼠耐受腹腔注射高达100mg/kg体重的3JC48-3，且无剂量限制性毒性。这些PDX小鼠模型的初步结果表明，3JC48-3可能有效地降低肿瘤生长速率。总之，我们的研究表明，3JC48-3是一种有效的MYC/MAX异源二聚化抑制剂，可降低前列腺癌的生长和活力，这与PrKD1表达和激酶活性的上调相关。
