HPV 16 E6/E7 up-regulate the expression of both HIF-1? and GLUT1 by inhibition of RRAD and activation of NF-?B in lung cancer cells.
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ABSTRACT: Chronic infection of HPV16 E6/E7 is frequently associated with lung cancers, especially in non-smokers and in Asians. In our previous studies, we found that HPV16 E6/E7 up-regulated HIF-1? at protein level and further up-regulated GLUT1 at both protein and mRNA levels in well-established lung cancer cell lines. In one of our further mechanism study, the results demonstrated that HPV16 E6/E7 up-regulated the expression of GLUT1 through HPV-LKB1-HIF-1?-GLUT1 axis. However, there are multiple pathways involved in HPV16 E6/E7 regulation of HIF-1? expression. In current study, using double directional genetic manipulation in well-established lung cancer cell lines, we showed that both E6 and E7 down-regulated the expression of RRAD at both protein and mRNA levels. Like LKB1, RRAD is one of the cancer suppressor genes. The loss of RRAD further activated NF-?B by promoted cytoplasmic p65 translocated to nucleus, and up-regulated the expression level of the p-p65 in nucleus. Furthermore, p-p65 up regulated HIF-1? and GLUT1 at both protein and mRNA levels. Thus, we proposed HPV16 E6/E7 up-regulated the expression of GLUT1 through HPV-RRAD-p65- HIF-1?- GLUT1 axis. In conclusion, we demonstrated for the first time that E6 and E7 promoted the expression of HIF-1? and GLUT1 by relieving the inhibitory effect of RRAD which resulted in the activation of NF-?B by promoting cytoplasmic p65 translocated to nucleus, and up-regulated the expression of the p-p65 in nucleus in lung cancer cells. Our findings provided new evidence to support the critical role of RRAD in the pathogenesis of HPV-related lung cancer, and suggested novel therapeutic targets.
SUBMITTER: Gu NJ
PROVIDER: S-EPMC6909954 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
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