Liver Cancer Institute, Zhongshan Hospital, and Key Laboratory of Carcinogenesis and Cancer Invasion (Ministry of Education), Fudan University, 180 Fenglin Road, Shanghai, 200032, People's Republic of China.
Cancer Research Institute, Fudan University Shanghai Cancer Center, Shanghai, People's Republic of China.
BMC Cancer. 2017 Sep 13;17(1):648. doi: 10.1186/s12885-017-3633-6.
FOXP3 has been discovered to be expressed in tumor cells and participate in the regulation of tumor behavior. Herein, we investigated the clinical relevance and biological significance of FOXP3 expression in human hepatocellular carcinoma (HCC).
Expression profile of FOXP3 was analyzed using real-time RT-PCR, western blotting and immunofluorescence on HCC cell lines, and immunostaing of a tissue microarray containing of 240 primary HCC samples. The potential regulatory roles of FOXP3 were dissected by an integrated approach, combining biochemical assays, analysis of patient survival, genetic manipulation of HCC cell lines, mouse xenograft tumor models and chromatin immunoprecipitation (ChIP) sequencing.
FOXP3 was constitutively expressed in HCC cells with the existence of splice variants (especially exon 3 and 4 deleted, Δ3,4-FOXP3). High expression of FOXP3 significantly correlated with low serum α-fetoprotein (AFP) level, absence of vascular invasion and early TNM stage. Survival analyses revealed that increased FOXP3 expression was significantly associated with better survival and reduced recurrence, and served as an independent prognosticator for HCC patients. Furthermore, FOXP3 could potently suppress the proliferation and invasion of HCC cells in vitro and reduce tumor growth in vivo. However, Δ3,4-FOXP3 showed a significant reduction in the tumor-inhibiting effect. The inhibition of FOXP3 on HCC aggressiveness was acted probably by enhancing the TGF-β/Smad2/3 signaling pathway.
Our findings suggest that FOXP3 suppresses tumor progression in HCC via TGF-β/Smad2/3 signaling pathway, highlighting the role of FOXP3 as a prognostic factor and novel target for an optimal therapy against this fatal malignancy.
FOXP3 已被发现表达于肿瘤细胞中，并参与调节肿瘤行为。在此，我们研究了 FOXP3 在人肝细胞癌（HCC）中的表达与临床相关性和生物学意义。
使用实时 RT-PCR、western blot 和免疫荧光法分析 HCC 细胞系中 FOXP3 的表达谱，并对包含 240 例原发性 HCC 样本的组织微阵列进行免疫染色。通过生化分析、患者生存分析、HCC 细胞系的遗传操作、小鼠异种移植肿瘤模型和染色质免疫沉淀（ChIP）测序等综合方法，剖析 FOXP3 的潜在调控作用。
FOXP3 在 HCC 细胞中持续表达，并存在剪接变异体（尤其是缺失外显子 3 和 4 的 Δ3,4-FOXP3）。FOXP3 的高表达与低血清甲胎蛋白（AFP）水平、无血管侵犯和早期 TNM 分期显著相关。生存分析显示，FOXP3 表达增加与更好的生存和降低复发显著相关，是 HCC 患者的独立预后因素。此外，FOXP3 可在体外强力抑制 HCC 细胞的增殖和侵袭，并减少体内肿瘤生长。然而，Δ3,4-FOXP3 显示出显著降低的肿瘤抑制作用。FOXP3 对 HCC 侵袭性的抑制作用可能是通过增强 TGF-β/Smad2/3 信号通路实现的。
我们的研究结果表明，FOXP3 通过 TGF-β/Smad2/3 信号通路抑制 HCC 肿瘤进展，凸显了 FOXP3 作为预后因素和针对这种致命恶性肿瘤的新型治疗靶点的作用。
