HPV16 E6/E7 Promote The Glucose Uptake Of GLUT1 In Lung Cancer Cells Through Downregulation Of Txnip Due To Inhibition Of PTEN Phosphorylation

Objective: High-risk human papillomavirus(HPV)infection might play an important role in the development of lung carcinoma(NSCLC).Our previous studies have shown that HPV 16 E6 and E7 could up-regulate the expression of glucose transporter 1(GLUT1)in lung cancer.However,whether they can promote the glucose uptake by GLUT1 and their underlying molecular mechanism have not been identified.It has been reported that thioredoxin interacting protein(TXNIP)regulates both the expression of GLUT1 and its glucose uptake.However,whether there is an association between HPV16 and TXNIP has not been reported.In this study,we explored the regulatory effect of HPV 16 on TXNIP and GLUT1 in lung cancer and its potential mechanism.Methods: 1.In this study,we upregulated E6/E7 in H1299 cell line and downregulated in A549 cell line by plasmid transfection and si RNA transfection.Using Western blotting and q RT-PCR to detect both the protein and m RNA expression of E6,E7,PTEN,p-PTEN,TXNIP,HIF-1?,GLUT1 in lung cancer cell lines.2.PTEN-specific si RNA and TXNIP-specific si RNA was used to knockdown the expression of PTEN and TXNIP respectivily.Using Western blotting and q RT-PCR to detect both the protein and m RNA expression of TXNIP,HIF-1?,GLUT1 in lung cancer cell lines.3.Using a nuclear plasma separation technology detected both the nucleus and cytoplasmic expression of HIF-1?.4.We knocked down TXNIP and measured the levels of glucose uptake using glucose uptake assay.Results: 1.Overexpression of E6 or E7 downregulated the phosphorylation of PTEN and expression of TXNIP but elevated the expression of HIF-1? and GLUT1.2.Inhibition of both E6 and E7 led to the upregulation of phosphorylated PTEN and TXNIP,whereas it resulted in the downregulation of the expression of HIF-1? and GLUT1.3.Inhibition of PTEN led to downregulation of TXNIP,whereas the expression of HIF-1? and GLUT1 was upregulated.4.Knockdown of TXNIP resulted in the elevated expression of HIF-1? and GLUT1.5.Knockdown of TXNIP enhanced the levels of HIF-1? in the nucleus but downregulated the levels of HIF-1? in the nucleus.6.TXNIP knockdown elevated the expression of GLUT1 and promoted the glucose uptake of lung cancer.Conclusion: 1.Both E6 and E7 down-regulate the expression of TXNIP by inhibiting the phosphorylation of PTEN,leading to the accumulation of HIF-1? in the nucleus,up-regulating the expression of GLUT and promoting the glucose uptake by GLUT1 in lung cancer.2.Our findings provide new evidence for the important role of TXNIP in the pathogenesis of HPV-associated lung cancer and a potential target for the treatment of HPV-associated lung cancer.