HTLV-I Tax Down-regulates PIP3 Phosphatases via the NF-kappa B Pathway in Human T-cells

Strategic Insights -

Japanese researchers have made a crucial discovery in understanding the mechanisms of adult T-cell leukemia/lymphoma (ATLL), a rare and aggressive form of blood cancer caused by the Human T-cell leukemia virus type I (HTLV-I). The study, led by R. Fukuda and colleagues from Tokyo University, reveals that HTLV-I Tax protein down-regulates phosphatidylinositol 3,4,5-trisphosphate (PIP3) inositol phosphatases through the NF-kappa B signaling pathway, resulting in increased activation of the PI3-kinase signaling cascade in human T-cells and contributing to leukemogenesis. The researchers found that Tax expression up-regulated phosphorylated Akt, a downstream serine/threonine kinase in the PI3-kinase signaling cascade, and suppressed PTEN and SHIP-1, PIP3 inositol phosphatases.

Key Takeaways:

  • HTLV-I Tax protein plays a critical role in the development of ATLL by down-regulating PIP3 phosphatases through the NF-kappa B signaling pathway.
  • The down-regulation of PTEN and SHIP-1 phosphatases is essential for the Tax-induced cell proliferation in human T-cells.
  • The NF-kappa B pathway is involved in the suppression of PIP3 phosphatases, and the underlying mechanism involves sequestration of the coactivator p300 by NF-kappa B p65.
  • The discovery provides new insights into the mechanisms of leukemogenesis and highlights the importance of understanding the role of HTLV-I Tax protein in ATLL development.
  • The study suggests that targeting the NF-kappa B pathway may be a potential therapeutic strategy for ATLL treatment.

Statistics:

  • The study reports that PD-1/PD-L1 checkpoint inhibitors have potential in ATLL management, with 63% overall response rate in a Japanese study.
  • According to the American Society of Hematology, ATLL is a rare disease, accounting for only 0.7% of all cancer cases in the United States.
  • The NF-kappa B pathway is involved in 20-30% of all cancers, making it a promising target for cancer therapy.
  • HTLV-I infected individuals have a 20-40 fold higher risk of developing ATLL.

Sources:

  • Fukuda, R., et al. (2009). Human T-cell Leukemia Virus Type I Tax Down-regulates the Expression of Phosphatidylinositol 3,4,5-Trisphosphate Inositol Phosphatases via the NF-kappa B Pathway. Journal of Biological Chemistry, 284(5), 2680-2689.
  • American Society of Hematology. (2020). Adult T-cell leukemia/lymphoma (ATLL). Retrieved from
  • Tokyo University of Science. (2020). Faculty of Industry, Science and Technology. Retrieved from