Anti-HIV type 1 Tat Monoclonal antibody, Clone 2E10E6

It has been shown that human and murine fibroblasts can be reprogrammed by ectopic expression of transcription factors using viral vectors. For the purpose of human therapeutic applications, the integration of viral transgenes into the genome is unlikely to be accepted. We therefore produced recombinant transcription factor proteins in E. coli (OCT4, SOX2, c-MYC and KLF4) carrying the cell penetrating TAT domain from HIV1. The purified proteins were able to enter into mammalian cells when added to tissue culture medium but appeared not to translocate to the nucleus. Further investigation indicated that most of the protein was tied up in the endosomes and was unavailable for reprogramming. Once this problem has been solved it seems likely that protein reprogramming will be the method of choice for clinical applications.

Lung cancer patients with human immunodeficiency virus (HIV) have a poorer prognosis than do patients without HIV infection. HIV1 Tat is a secreted viral protein that penetrates the plasma membrane and interacts with a number of proteins in non-HIV-infected cells. The loss of function of Tat-interacting protein 30 (TIP30) has been linked to metastasis in non-small cell lung cancer (NSCLC). However, it is unknown how the interaction of HIV1 Tat with TIP30 regulates the metastasis of NSCLC cells. In this study, the overexpression of TIP30 decreased tumor growth factor--induced epithelial-to-mesenchymal transition (EMT) and invasion of NSCLC cells, whereas the knockdown of TIP30 promoted EMT, invasion and stemness. Exposure to recombinant HIV1 Tat proteins promoted EMT and invasion. A mechanistic study showed that the interaction of HIV1 Tat with TIP30 blocked the binding of TIP30 to importin-, which is required for the nuclear translocation of Snail. Indeed, the loss of TIP30 promoted the nuclear translocation of Snail. In vivo studies demonstrated that the overexpression of TIP30 inhibited the metastasis of NSCLC cells. In contrast, the coexpression of HIV1 Tat and TIP30 diminished the inhibitory effect of TIP30 on metastasis. Immunohistochemistry confirmed that TIP30 overexpression reduced the nuclear localization of Snail, whereas the coexpression of HIV1 Tat and TIP30 increased nuclear Snail in metastatic tumors. In conclusion, the binding of HIV1 Tat to TIP30 enhanced EMT and metastasis by regulating the nuclear translocation of Snail. Targeting Tat-interacting proteins may be a potential therapeutic strategy to prevent metastasis in NSCLC patients with HIV infection.