Tu Min, Li Haifeng, Lv Nan, Xi Chunhua, Lu Zipeng, Wei Jishu, Chen Jianmin, Guo Feng, Jiang Kuirong, Song Guoxin, Gao Wentao, Miao Yi
Pancreas Center, The First Affiliated Hospital with Nanjing Medical University, Nanjing, 210029, People's Republic of China.
Department of Pathology, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
Mol Cancer. 2017 Mar 21;16(1):66. doi: 10.1186/s12943-017-0619-6.
Vasohibin 2 (VASH2) has previously been identified as an agiogenenic factor and a cancer related protein. Here we investigated the association of VASH2 expression and chemoresistance in pancreatic cancer.
Immunohistochemical staining for VASH2 was performed on 102 human pancreatic cancer samples. Pancreatic cancer cell line models exhibiting overexpression or knockdown of VASH2 were generated. Gene expression analyses were carried out to determine genes differentially regulated by VASH2. Putative transcription factors that are downstream mediators of gene expression regulated by VASH2 were queried bioinformatically. Dual-luciferase reporter assays and ChIP assays were performed to confirm transactivation of target genes following VASH2 overexpression or knockdown.
VASH2 protein expression was higher in human pancreatic cancer than in paired adjacent tissues and elevated VASH2 levels were associated with gemcitabine chemoresistance. In cell line models of pancreatic cancer, VASH2 expression induced gemcitabine chemoresistance in vitro and in vivo. It was discovered that expression of ribonucleotide reductase regulatory subunit M2 (RRM2) is regulated by VASH2; immunohistochemical analysis demonstrated a positive association of VASH2 expression and RRM2 expression in human pancreatic cancer tissues. Bioinformatics analyses revealed that induction of the Jun proto-oncogene (JUN) by VASH2 is responsible for upregulation of RRM2 expression; this JUN-dependent regulation of RRM2 by VASH2 was confirmed by chromatin immunoprecipitation and dual luciferase reporter assays, which demonstrated that JUN directly binds with the RRM2 promoter to activate transcription.
These data suggest that VASH2 reduces the chemosensitivity to gemcitabine in pancreatic cancer cells via JUN-dependent transactivation of RRM2.
血管抑制素2（VASH2）先前已被鉴定为一种血管生成抑制因子和一种癌症相关蛋白。在此，我们研究了VASH2表达与胰腺癌化疗耐药性之间的关联。
对102例人胰腺癌样本进行VASH2免疫组织化学染色。构建了VASH2过表达或敲低的胰腺癌细胞系模型。进行基因表达分析以确定受VASH2差异调节的基因。通过生物信息学方法查询作为VASH2调节基因表达下游介质的假定转录因子。进行双荧光素酶报告基因检测和染色质免疫沉淀检测，以确认VASH2过表达或敲低后靶基因的反式激活。
人胰腺癌中VASH2蛋白表达高于配对的相邻组织，VASH2水平升高与吉西他滨化疗耐药相关。在胰腺癌细胞系模型中，VASH2表达在体外和体内均诱导吉西他滨化疗耐药。发现核糖核苷酸还原酶调节亚基M2（RRM2）的表达受VASH2调节；免疫组织化学分析表明，人胰腺癌组织中VASH2表达与RRM2表达呈正相关。生物信息学分析显示，VASH2对原癌基因Jun（JUN）的诱导导致RRM2表达上调；染色质免疫沉淀和双荧光素酶报告基因检测证实了VASH2对RRM2的这种JUN依赖性调节，表明JUN直接与RRM2启动子结合以激活转录。
这些数据表明，VASH2通过JUN依赖性的RRM2反式激活降低胰腺癌细胞对吉西他滨的化疗敏感性。
