背景:垂体神经内分泌肿瘤,PitNET,在目前治疗难以治疗的远处转移中通常具有侵袭性和沉淀性。然而,PitNETs侵袭性的分子机制还没有得到很好的理解。发育多能性相关基因4(DPPA4)被称为干细胞调控基因,在某些癌症中过度表达。但它在PitNETs\'侵略性背景下的功能尚不清楚。
方法:我们采用了PitNET的大鼠和人模型。在大鼠垂体肿瘤模型(RPT)中,我们使用产前酒精暴露(PAE)雌性Fischer大鼠,这些大鼠在雌激素治疗后发展出侵略性PitNETs,而在人类垂体肿瘤(HPT)模型中,我们使用了手术患者垂体瘤的积极增殖细胞。各种分子,细胞,和表观遗传技术用于确定DPPA4在PitNETs侵袭性中的作用。
结果:我们显示DPPA4在PAE大鼠和人类患者的侵袭性PitNETs中过表达与细胞干性因子增加相关。基因编辑实验表明,DPPA4增加了细胞干细胞和肿瘤侵袭性基因的表达,并促进增殖,殖民,迁移,和PitNET细胞的致瘤潜能。ChIP分析和受体拮抗作用研究表明,DPPA4与经典WINTs启动子结合,并直接或间接增加Wnt/β-catenin对细胞干性的控制,肿瘤生长,以及PitNET的侵略性。表观遗传学研究表明,组蛋白甲基转移酶参与DPPA4的酒精激活。
结论:这些发现支持DPPA4在肿瘤干性和侵袭性方面的作用,并为调节这种干性调节剂治疗PitNETs提供了临床前理论基础。
BACKGROUND: Pituitary neuroendocrine tumors, PitNETs, are often aggressive and precipitate in distant metastases that are refractory to current therapies. However, the molecular mechanism in PitNETs\' aggressiveness is not well understood. Developmental pluripotency-associated 4 (DPPA4) is known as a stem cell regulatory gene and overexpressed in certain cancers, but its function in the context of PitNETs\' aggressiveness is not known.
METHODS: We employed both rat and human models of PitNETs. In the rat pituitary tumor model (RPT), we used prenatal-alcohol-exposed (PAE) female Fischer rats which developed aggressive PitNETs following estrogen treatment, while in the human pituitary tumor (HPT) model, we used aggressively proliferative cells from pituitary tumors of patients undergone surgery. Various molecular, cellular, and epigenetic techniques were used to determine the role of DPPA4 in PitNETs\' aggressiveness.
RESULTS: We show that DPPA4 is overexpressed in association with increased cell stemness factors in aggressive PitNETs of PAE rats and of human patients. Gene-editing experiments demonstrate that DPPA4 increases the expression of cell stemness and tumor aggressiveness genes and promotes proliferation, colonization, migration, and tumorigenic potential of PitNET cells. ChIP assays and receptor antagonism studies reveal that DPPA4 binds to canonical WINTs promoters and increases directly or indirectly the Wnt/β-catenin control of cell stemness, tumor growth, and aggressiveness of PitNETs. Epigenetic studies show involvement of histone methyltransferase in alcohol activation of DPPA4.
CONCLUSIONS: These findings support a role of DPPA4 in tumor stemness and aggressiveness and provide a preclinical rationale for modulating this stemness regulator for the treatment of PitNETs.