Head and neck squamous cell carcinoma (HNSCC) is commonly associated with tobacco and alcohol consumption that induce a “precancerous field,” with phosphoinositide 3-kinase (PI3K) signaling being a common driver. However, the preclinical effectiveness of PI3K inhibitors has not necessarily translated to remarkable benefit in HNSCC patients. Thus, we sought to determine how precancerous keratinocytes influence HNSCC proliferation, cancer stem cell (CSC) maintenance, and response to PI3K inhibitors. We used the NOK keratinocyte cell line as a model of preneoplastic keratinocytes because it harbors two frequent genetic events in HNSCC, CDKN2A promoter methylation and TP53 mutation, but does not form tumors. NOK cell coculture or NOK cell-conditioned media promoted HNSCC proliferation, PI3K inhibitor resistance, and CSC phenotypes. SOMAscan-targeted proteomics determined the relative levels of >1300 analytes in the media conditioned by NOK cells and HNSCC cells ± PI3K inhibitor. These results demonstrated that NOK cells release abundant levels of ligands that activate epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor (FGFR), two receptor tyrosine kinases with oncogenic activity. Inhibition of EGFR, but not FGFR, blunted PI3K inhibitor resistance and CSC phenotypes induced by NOK cells. Our results demonstrate that precancerous keratinocytes can directly support neighboring HNSCC by activating EGFR. Importantly, PI3K inhibitor sensitivity was not necessarily a cancer cell-intrinsic property, and the tumor microenvironment impacts therapeutic response and supports CSCs. Additionally, combined inhibition of EGFR with PI3K inhibitor diminished EGFR activation induced by PI3K inhibitor and potently inhibited cancer cell proliferation and CSC maintenance.

中文翻译：

---

癌前角质形成细胞中的表皮生长因子受体信号传导促进邻近头颈癌、鳞状细胞癌、癌症干细胞样特性和磷酸肌醇3激酶抑制剂不敏感性

头颈鳞状细胞癌 (HNSCC) 通常与诱发“癌前病变”的吸烟和饮酒有关，其中磷酸肌醇 3 激酶 (PI3K) 信号传导是常见的驱动因素。然而，PI3K 抑制剂的临床前有效性并不一定能转化为 HNSCC 患者的显着获益。因此，我们试图确定癌前角质形成细胞如何影响 HNSCC 增殖、癌症干细胞 (CSC) 维持以及对 PI3K 抑制剂的反应。我们使用 NOK 角质形成细胞系作为癌前角质形成细胞的模型，因为它在 HNSCC 中具有两个常见的遗传事件：CDKN2A启动子甲基化和TP53突变，但不形成肿瘤。NOK 细胞共培养或 NOK 细胞条件培养基促进 HNSCC 增殖、PI3K 抑制剂耐药性和 CSC 表型。SOMAscan 靶向蛋白质组学确定了由 NOK 细胞和 HNSCC 细胞 ± PI3K 抑制剂调节的培养基中 >1300 种分析物的相对水平。这些结果表明，NOK 细胞释放大量配体，激活表皮生长因子受体 (EGFR) 和成纤维细胞生长因子受体 (FGFR)，这两种受体酪氨酸激酶具有致癌活性。抑制 EGFR，但不抑制 FGFR，减弱了 NOK 细胞诱导的 PI3K 抑制剂耐药性和 CSC 表型。我们的结果表明，癌前角质形成细胞可以通过激活 EGFR 直接支持邻近的 HNSCC。重要的，PI3K 抑制剂敏感性不一定是癌细胞固有的特性，肿瘤微环境会影响治疗反应并支持 CSC。此外，EGFR 与 PI3K 抑制剂的联合抑制可减少 PI3K 抑制剂诱导的 EGFR 激活，并有效抑制癌细胞增殖和 CSC 维持。