转录因子（TFs）和N6-甲基腺苷（m6A）修饰酶通过基因的转录调控和转录后调控分别参与肿瘤进展。然而，这两种类型的基因表达调节因子在头颈鳞状细胞癌（HNSC）中的相互作用和作用机制尚不清楚。在本研究中，我们证明转录因子homeobox-D1（HOXD1）和甲基腺苷脱甲基酶脂肪质量和肥胖相关蛋白（FTO）形成一个正反馈环路，在HNSC中促进细胞增殖和存活。临床上，HOXD1表达在多种癌症类型中发生异常，并与HNSC、胃腺癌、子宫体内膜癌和嗜铬细胞瘤及嗜纵泡红细胞瘤患者的预后较差相关。机制上，FTO在HNSC肿瘤样本中过表达，并以m6A依赖性的方式正调节HOXD1的表达。功能上，HOXD1的缺失改善了HNSC细胞对凋亡的抵抗能力，并抑制了肿瘤细胞在G0/G1期的停滞，从而抑制了细胞增长，而HOXD1的过表达则产生了相反的效果。此外，HOXD1通过直接靶向FTO的启动子激活了致癌因子FTO的转录。FTO的下调效果模拟了HOXD1敲除对HNSC的生物学影响。重要的是，HOXD1的过表达显著拯救了FTO缺失引起的HNSC细胞增殖抑制和凋亡促进。综上所述，我们的研究结果揭示了HOXD1作为一种新的预后预测因子和HNSC的潜在靶点，并为HOXD1-FTO回路在该癌症中的作用机制提供了机械性洞察。©2023国际细胞生物学联合会。

Transcription factors (TFs) and N6-methyladenosine (m6A) modifiers are involved in tumor progression through transcriptional regulation and posttranscriptional regulation of genes, respectively. However, the crosstalk and role of these two types of gene expression regulators in head and neck squamous cell carcinoma (HNSC) remains poorly understood. In this study, we demonstrate that the TF homeobox-D1 (HOXD1) and the m6A demethylase fat mass and obesity-associated protein (FTO) form a positive feedback loop to promote cell proliferation and survival in HNSC. Clinically, HOXD1 expression is dysregulated in multiple cancer types and is associated with worse prognosis in patients with HNSC, stomach adenocarcinoma, uterine corpus endometrial carcinoma, and pheochromocytoma and paraganglioma. Mechanistically, FTO is overexpressed in HNSC tumor samples and positively regulates HOXD1 expression in an m6A-dependent manner. Functionally, deficiency of HOXD1 relieved the resistance of HNSC cells to apoptosis and arrested tumor cells at the G0/G1 phase, thereby inhibiting cell growth, whereas overexpression of HOXD1 caused the opposite effect. Furthermore, HOXD1 activates the transcription of the oncogenic factor FTO by directly targeting its promoter. Downregulation of FTO mimicked the biological effect of HOXD1 knockdown on HNSC. Importantly, overexpression of HOXD1 significantly rescued the proliferation inhibition and apoptosis promotion of HNSC cells induced by deficiency of FTO. Together, our findings reveal HOXD1 as a novel prognostic predictor and a potential target for HNSC, providing mechanistic insights into the role of the HOXD1-FTO circuit in this cancer.© 2023 International Federation of Cell Biology.