Katkoori Venkat R, Manne Upender, Chaturvedi Lakshmi S, Basson Marc D, Haan Pam, Coffey Daniel, Bumpers Harvey L
Department of Surgery, Michigan State University, College of Human Medicine, Lansing, MI, USA.
Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA.
Oncotarget. 2017 Aug 29;8(44):76574-76586. doi: 10.18632/oncotarget.20580. eCollection 2017 Sep 29.
The codon 72 polymorphism in p53 has been implicated in colorectal cancer (CRC) risk, prognosis and CRC health disparities. We examined the functional consequence of this polymorphism in CRC.
Plasmids (pCMV6) that express different phenotypes of p53 [p53 wild type (wt) at codon 72 (R72), R72 with mutation at codon 273 cysteine (R72), p53 mutation at codon 72 (P72) and P72 with mutation at codon 273 (P72)] were constructed. The CRC cell line Caco2, which does not express p53 for studies, was used as host. CRC xenografts were established in severe combined immunodeficient (SCID) mice using established cell lines. CRC surgical specimens, corresponding normal colon, and tumor xenografts were sequenced for codon 72 polymorphism of p53. Proteins signaling mechanisms were evaluated to assess the functional consequence of P72 phenotype of p53.
This study demonstrated a significantly increased survival of cells expressing P72, mutant phenotype, versus R72 phenotype. WB analyses revealed that P72 induced activation of p38 and RAF/MEK/ extracellular signal-regulated kinase (ERK) MAP kinases. Activation of CREB was found to be higher in tumors that exhibit P72 phenotype. Metastatic lesions of CRC expressed more phospho-CREB than non-metastatic lesions. The expression of P72 promoted CRC metastasis.
P72 contributes to the aggressiveness of CRC. Because P72 is over-expressed in CRC, specifically in African-American patients, this suggests a role for P72 in cancer health disparities. This work was supported by NIH/NCI Workforce Diversity Grant R21-CA171251 & U54CA118948.
p53基因第72位密码子多态性与结直肠癌（CRC）风险、预后及CRC健康差异有关。我们研究了该多态性在CRC中的功能后果。
构建了表达p53不同表型的质粒（pCMV6）[第72位密码子为野生型（wt）的p53（R72）、第273位半胱氨酸密码子发生突变的R72、第72位密码子发生突变的p53（P72）以及第273位密码子发生突变的P72]。不表达p53用于研究的CRC细胞系Caco2用作宿主。使用已建立的细胞系在严重联合免疫缺陷（SCID）小鼠中建立CRC异种移植模型。对CRC手术标本、相应的正常结肠组织和肿瘤异种移植模型进行p53基因第72位密码子多态性测序。评估蛋白质信号传导机制以评估p53的P72表型的功能后果。
本研究表明，表达突变表型P72的细胞与R72表型相比，存活率显著提高。蛋白质免疫印迹分析显示，P72诱导p38和RAF/MEK/细胞外信号调节激酶（ERK）丝裂原活化蛋白激酶激活。在表现出P72表型的肿瘤中，发现CREB的激活水平更高。CRC转移灶中磷酸化CREB的表达高于非转移灶。P72的表达促进了CRC转移。
P72促进了CRC的侵袭性。由于P72在CRC中过度表达，尤其是在非裔美国患者中，这表明P72在癌症健康差异中发挥作用。本研究得到了美国国立卫生研究院/国立癌症研究所劳动力多样性资助R21-CA171251和U54CA118948的支持。
