Research Center of Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53, Brno, Czech Republic.
Cell Mol Biol Lett. 2022 Feb 23;27(1):18. doi: 10.1186/s11658-022-00323-x.
ΔNp63 overexpression is a common event in squamous cell carcinoma (SCC) that contributes to tumorigenesis, making ΔNp63 a potential target for therapy.
We created inducible TP63-shRNA cells to study the effects of p63-depletion in SCC cell lines and non-malignant HaCaT keratinocytes. DNA damaging agents, growth factors, signaling pathway inhibitors, histone deacetylase inhibitors, and metabolism-modifying drugs were also investigated for their ability to influence ΔNp63 protein and mRNA levels.
HaCaT keratinocytes, FaDu and SCC-25 cells express high levels of ΔNp63. HaCaT and FaDu inducible TP63-shRNA cells showed reduced proliferation after p63 depletion, with greater effects on FaDu than HaCaT cells, compatible with oncogene addiction in SCC. Genotoxic insults and histone deacetylase inhibitors variably reduced ΔNp63 levels in keratinocytes and SCC cells. Growth factors that regulate proliferation/survival of squamous cells (IGF-1, EGF, amphiregulin, KGF, and HGF) and PI3K, mTOR, MAPK/ERK or EGFR inhibitors showed lesser and inconsistent effects, with dual inhibition of PI3K and mTOR or EGFR inhibition selectively reducing ΔNp63 levels in HaCaT cells. In contrast, the antihyperlipidemic drug lovastatin selectively increased ΔNp63 in HaCaT cells.
These data confirm that ΔNp63-positive SCC cells require p63 for continued growth and provide proof of concept that p63 reduction is a therapeutic option for these tumors. Investigations of ΔNp63 regulation identified agent-specific and cell-specific pathways. In particular, dual inhibition of the PI3K and mTOR pathways reduced ΔNp63 more effectively than single pathway inhibition, and broad-spectrum histone deacetylase inhibitors showed a time-dependent biphasic response, with high level downregulation at the transcriptional level within 24 h. In addition to furthering our understanding of ΔNp63 regulation in squamous cells, these data identify novel drug combinations that may be useful for p63-based therapy of SCC.
ΔNp63 过表达是鳞状细胞癌（SCC）中的常见事件，有助于肿瘤发生，使 ΔNp63 成为治疗的潜在靶点。
我们创建了诱导型 TP63-shRNA 细胞，以研究 p63 耗竭对 SCC 细胞系和非恶性 HaCaT 角质形成细胞的影响。还研究了 DNA 损伤剂、生长因子、信号通路抑制剂、组蛋白去乙酰化酶抑制剂和代谢修饰药物对 ΔNp63 蛋白和 mRNA 水平的影响。
HaCaT 角质形成细胞、FaDu 和 SCC-25 细胞表达高水平的 ΔNp63。HaCaT 和 FaDu 诱导型 TP63-shRNA 细胞在 p63 耗竭后增殖减少，FaDu 细胞比 HaCaT 细胞的影响更大，与 SCC 中的癌基因成瘾一致。遗传毒性刺激物和组蛋白去乙酰化酶抑制剂可使角质形成细胞和 SCC 细胞中的 ΔNp63 水平发生不同程度的降低。调节鳞状细胞增殖/存活的生长因子（IGF-1、EGF、 Amphiregulin、KGF 和 HGF）和 PI3K、mTOR、MAPK/ERK 或 EGFR 抑制剂的作用较小且不一致，PI3K 和 mTOR 双重抑制或 EGFR 抑制选择性降低 HaCaT 细胞中的 ΔNp63 水平。相比之下，降脂药 lovastatin 选择性增加 HaCaT 细胞中的 ΔNp63。
这些数据证实 ΔNp63 阳性 SCC 细胞需要 p63 才能持续生长，并为 p63 减少是这些肿瘤的治疗选择提供了概念验证。对 ΔNp63 调节的研究确定了特定于药物和细胞的途径。特别是，PI3K 和 mTOR 通路的双重抑制比单一通路抑制更有效地降低 ΔNp63，广谱组蛋白去乙酰化酶抑制剂表现出时间依赖性的双相反应，在 24 小时内转录水平的下调幅度较高。除了进一步了解鳞状细胞中 ΔNp63 的调节外，这些数据还确定了新的药物组合，这些组合可能对基于 p63 的 SCC 治疗有用。
