Molecular Oncology Laboratory, Department of Zoology, University of Delhi (North Campus), New Delhi, India.
Molecular Oncology Laboratory, Department of Zoology, University of Delhi (North Campus), New Delhi, India; Department of Zoology, Deshbandhu College, University of Delhi, Delhi, India.
Biochim Biophys Acta Mol Basis Dis. 2023 Dec;1869(8):166817. doi: 10.1016/j.bbadis.2023.166817. Epub 2023 Jul 31.
The constitutive activation and aberrant expression of Signal Transducer and Activator of Transcription 3 (STAT3) plays a key role in initiation and progression of cervical cancer (CaCx). How STAT3 influences HPV transcription is poorly defined. In the present study, we probed direct and indirect interactions of STAT3 with HPV16/18 LCR. In silico assessment of cis-elements present on LCR revealed the presence of potential STAT3 binding motifs. However, experimental validation by ChIP-PCR could not confirm any specific STAT3 binding on HPV16 LCR. Protein-protein interaction (PPI) network analysis of STAT3 with other host transcription factors that bind LCR, highlighted the physical association of STAT3 with c-FOS and c-JUN. This was further confirmed in vitro by co-immunoprecipitation, where STAT3 co-immunoprecipitated with c-FOS and c-JUN in CaCx cells. The result was supported by immunocytochemical analysis and colocalization of STAT3 with c-FOS and c-JUN. Positive signals in proximity ligation assay validated physical interaction and colocalization of STAT3 with AP1. Colocalization of STAT3 with c-FOS and c-JUN increased upon IL-6 treatment and decreased post-Stattic treatment. Alteration of STAT3 expression affected the subcellular localization of c-FOS and c-JUN, along with the expression of viral oncoproteins (E6 and E7) in CaCx cells. High expression of c-JUN in tumor tissues correlated with poor prognosis in both HPV16 and HPV18 CaCx cohort whereas high expression of STAT3 correlated with poor prognosis in HPV18 CaCx lesions only. Overall, the data suggest an indirect interaction of STAT3 with HPV LCR via c-FOS and c-JUN and potentiate transcription of viral oncoproteins.
信号转导和转录激活因子 3（STAT3）的组成性激活和异常表达在宫颈癌（CaCx）的发生和发展中起着关键作用。STAT3 如何影响 HPV 转录尚不清楚。在本研究中，我们探究了 STAT3 与 HPV16/18 LCR 的直接和间接相互作用。LCR 上顺式元件的计算机评估显示存在潜在的 STAT3 结合基序。然而，通过 ChIP-PCR 进行的实验验证不能证实 HPV16 LCR 上任何特定的 STAT3 结合。STAT3 与其他结合 LCR 的宿主转录因子的蛋白质-蛋白质相互作用（PPI）网络分析突出了 STAT3 与 c-FOS 和 c-JUN 的物理关联。这在体外通过共免疫沉淀进一步得到证实，其中 STAT3 在 CaCx 细胞中与 c-FOS 和 c-JUN 共免疫沉淀。免疫细胞化学分析和 STAT3 与 c-FOS 和 c-JUN 的共定位支持了这一结果。接近连接测定的阳性信号验证了 STAT3 与 AP1 的物理相互作用和共定位。IL-6 处理后，STAT3 与 c-FOS 和 c-JUN 的共定位增加，Stattic 处理后减少。STAT3 表达的改变影响了 c-FOS 和 c-JUN 的亚细胞定位，以及 CaCx 细胞中病毒癌蛋白（E6 和 E7）的表达。肿瘤组织中 c-JUN 的高表达与 HPV16 和 HPV18 CaCx 队列的预后不良相关，而 STAT3 的高表达仅与 HPV18 CaCx 病变的预后不良相关。总的来说，数据表明 STAT3 通过 c-FOS 和 c-JUN 与 HPV LCR 发生间接相互作用，并增强病毒癌蛋白的转录。
