Please see below for selected publications.
1. Metabolic reprogramming via TLR4-NANOG and Ob-R-STAT3 pathways in TICs: Based on insights from the genetic mouse model of HCC, we have initiated several IRB-approved clinical studies to further expand research to isolate, characterize and treat TICs derived from human HCC patients at USC. Using knowledge gained from the oncogenic signaling of TICs, we are addressing new mechanistic hypotheses based on the novel discovery that the pluripotent transcription factor, NANOG, can reprogram the metabolism of HCC-derived TICs (OXPHOS). Global mRNA profiling analysis identified NANOG (the stem/progenitor cell marker) as one of major downstream targets of TLR4 for oncogenesis. This study allowed me to merge my background in HCV research with knowledge of alcoholic liver disease and TICs using Tg mice. These studies will motivate novel strategies for targeting and removing TICs and suggest new avenues to treat malignancies associated with human HCV and alcoholism and/or obesity. TLR4-NANOG and Ob-R-STAT3 pathways in TICs synergistically activates EMT pathway through activation of TWIST1 (EMT) and disrupts asymmetric cell division complex formation (NUMB). This newly discovered mechanistic framework for TIC proliferation represents a key innovation and holds significant potential as a therapeutic target. I served as the primary investigator or co-investigator in all of these studies.
- OXPHOS: Chen C.L., Uthaya Kumar D., Punj V., Xu J., Sher L., Hess S., Machida K., NANOG metabolically reprograms tumor-initiating stem-like cells: oncogenic changes in oxidative phosphorylation and fatty acid metabolisms, Cell Metabolism, 23(1):206-219, 2016 (Impact factor: 17.6) PMCID: PMC4715587
- EMT: Uthaya Kumar D. B., Chen C.L., Liu, J.C., Feldman D., Sher L., French, S., DiNorcia J., French S.W., Naini B.V., Junrungsee S., Agopian V.G., Zarrinpar A., and Machida K., TLR4 Signaling via NANOG Cooperates With STAT3 to Activate Twist1 and Promote Formation of Tumor-initiating Stem-like Cells in Livers of Mice, Gastroenteroloy, 150(3), 707-719, 2015, NIHMSID: 737767 (Impact factor: 16.7), PMCID: PMC4766021
- NUMB: Siddique H, Chen C, Punj V, Sher L, Tahara S, Tokuhisa, Machida K, NUMB phosphorylation destabilizes p53 and promotes self-renewal of tumor-initiating cells by NANOG-dependent mechanism in liver cancer, Hepatology, 62(5):1466-1479, 2015, PMID: 26174965 (Impact factor: 11.1), PMCID: PMC4715587
2. Alcohol-TLR4-NANOG signaling in TICs: Based on this work which provided a new mechanistic insight into the important and clinically relevant HCV/alcohol-synergism, I am poised to develop an independent research program on TLR4-dependent, Nanog-mediated, liver oncogenesis by merging my background in HCV-induced liver oncogenesis with new areas of alcoholic liver disease (ALD), cancer stem cells, functional cDNA library screening, and high throughput genome-wide analysis. We investigated the roles of TIC signaling in human malignancies associated with virus and alcoholism and/or obesity. Further, Nanog, the progenitor/stem cell factor gene, was shown to be directly downstream of TLR4 activation and to contribute to NS5A/alcohol-mediated liver oncogenesis. We found that the hormone produced by adipose tissue, that controls appetite, stimulates self-renewal and expansion of TICs through the activation of tumor-generating genes (Ob-R). Furthermore, our study demonstrates that TLR4 is induced, activated, and responsible for liver oncogenesis in other HCC mouse models and that TICs isolated from these models are all TLR4-dependent. Further, Nanog, the progenitor/stem cell factor gene, was shown to be directly downstream of TLR4 activation and to contribute to NS5A/alcohol-mediated liver oncogenesis (TLR4-NANOG). I developed a research program on TLR4-dependent, Nanog-mediated, liver oncogenesis by merging my background in HCV-induced liver oncogenesis with new areas of alcoholic liver disease (ALD), cancer stem cells, functional cDNA library screening, and high throughput genome-wide analysis (TLR4-TGF).
We also established intragastric mouse feeding model to maximize alcohol infusion (iG).
- Ob-R: Feldman D.E., Chen C., Punj V., Tsukamoto H., Machida K., Pluripotency factor-mediated expression of the Leptin receptor OB-R links obesity to oncogenesis through tumor-initiating stem cells, Proc. Natl. Acad. Sci. USA., 109, 829-34, 2012 (Corresponding author), PMCID: 3271911
- TLR4-NANOG: Machida K.*, Tsukamoto H., Mkrtchyan H., Duan, L., Dynnyk A., Liu H., Wang J., Ray R., Ou, J., Seki E., Lai M.M.C., Toll-like receptor 4 mediates synergism between alcohol and HCV in hepatocellular carcinoma involving stem cell marker Nanog, Proc. Natl. Acad. Sci. USA,, 106, 1548-1553, 2009 (*Corresponding author), PMCID: 2635765
- TLR4-TGF: Chen C.L., Tsukamoto H., Liu J.C., Kashiwabara K., Feldman, D., Sher L., Dooley S., French S., Mishra L., Petrovic L., Hyeongnam J., Machida K., Reciprocal regulation by TLR4 oncogenic and TGF-β tumor suppressor pathways in liver tumor-initiating stem-like cells, J. Clin. Invest., 123, 2832-2849, 2013 (Corresponding author), PMCID: 3696549
- iG: Ueno A., Lazaro R., Wang P.Y., Higashiyama R., Machida K., and Tsukamoto H., Mouse Intragastric Infusion (iG) Model, Nature Protocol, 2012 Mar 29;7(4):771-81. PMCID: 4197794
3. HCV-TLR4 signaling: Our research addressed new mechanistic hypotheses based on the novel discovery that the HCV NS5A protein induces Toll-like receptor 4 (TLR4) an innate immune sensor molecule for Gram (-) bacteria. We also studied the synergy between HCV and alcoholism and delineating oncogenic signaling pathways. This study unveiled a novel finding of TLR4 induction by the HCV NS5A protein as a critical molecular event responsible for alcohol-induced synergistic liver oncogenesis.
- HCV-TLR4: Machida, K., Cheng, K.T., Sung, V.M., and Lai, M.M. Hepatitis C virus induces Toll-like receptor 4 expression, leading to enhanced production of IFN- and IL-6 J. Virol. 80:866-874, 2006, PMCID: 1346849
4. Viral oncogeneisis via mutator phenotype: We uncovered a novel finding in which HCV promotes genomic DNA damage and mutations (Hypermutation) that enable viral transformation (Mutator). Overall, these results define a unique strategy by which host tumor suppressor genes are effectively abolished by viral proteins. This research led to five first-author publications. Early on and continuing I focused on HCV molecular virological research and host-virus interactions.
- Mutator: Machida K., K. T. Cheng, V. M. Sung, S. Shimodaira, K. L. Lindsay, A. M. Levine, M. Y. Lai, and M. M. Lai, Hepatitis C virus induces a mutator phenotype: enhanced mutations of immunoglobulin and protooncogenes. Proc. Natl. Acad. Sci. USA. 101:4262-4267, 2004, PMCID: 384729 (Awarded by ISI due to Top 1% of citation in the field)
- Hypermutation: Machida, K., Cheng, K.T., Pavio, N. Sung, V.M., and Lai, M.M. Hepatitis C virus E2-CD81 interaction induces hypermutation of the immunoglobulin gene in B cells. J. Virol. 79:8079-8089, 2005, PMCID: 1143751 (Cited by Faculty 1000)
5. Viral oncogeneisis via DNA damage and repair defects: My research on HCV-induced oncogenesis has exploited a unique in vitro lymphocyte HCV infection model and liver specific HCV core Tg animals to uncover accentuated DNA mutations and defective DNA repair. We uncovered a novel finding in which HCV promotes genomic DNA damage via inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS), DNA repair defects (Defective DNA repair) and mutations that enable viral transformation through TLR4 or c-JUN pathways (c-JUN). We demonstrated mitochondrial oxidant stress and permeability transition and DNA damage as key pro-oncogenic alterations caused by HCV proteins (ROS). We also demonstrate that increased NO production by iNOS as a mechanism of DNA damage caused by HCV core and NS3 proteins in vitro and in vivo (iNOS). Overall, these results define a unique strategy by which host tumor suppressor genes are effectively abolished by viral proteins. This research led to five first-author publications.
- c-JUN: Machida, K.*, Tsukamoto, H., Liu, J.-C., Han, Y.-P., Govindarajan, S., Akira, S., Lai, M.M.C., and Ou, J.H.J. c-Jun mediates HCV hepatocarcinogenesis through STAT3 and nitric oxide-dependent impairment of oxidative DNA repair. Hepatology, 52(2):480-92, 2010 (Corresponding author), PMCID: 295838
- ROS: Hepatitis C Virus Triggers Mitochondrial Permeability Transition with Production of Reactive Oxygen Species, Leading to DNA Damage and STAT3 Activation. Machida K. et al., J. Virol. 80:7199-7207, 2006, PMCID: 3107125
- Defective DNA repair: Machida, K.*, McNamara, G., Cheng, K.T., Wang, C.H., Huang, J., Ou, J.H., and Lai M.M. Hepatitis C virus inhibits DNA damage-repair through disruption of ATM-NBS1/Mre11/Rad50 pathway, J. Immunol., 185(11):6985-6998, 2010, PMCID: 3101474 (Corresponding author: Cover page)
- iNOS: Hepatitis C virus infection activates the immunologic (type II) isoform of nitric oxide synthase and thereby enhances DNA damage and mutations of cellular genes. Machida K. et al., J. Virol. 78:8835-8843, 2004, PMCID: 479064
6. The mechanisms of HCV-induced HCC and lymphoma: I developed an interest in HCV-associated chronic liver diseases, virus-mediated immunoglobulin hypermutation (Hypermutaion) and proliferation (Lymphoproliferation) with more clinical relevance. Thus, when an opportunity arose to study the synergism between HCV and alcohol, I began to re-direct my research focus to this clinically important area. I acquired basic and advanced skills in molecular virology and genetic animal models to investigate abnormal apoptosis signaling and enhanced oncogenic potential in the liver of HCV transgenic (Tg) mice.
- Hypermutaion: Hepatitis C virus E2-CD81 interaction induces hypermutation of immunoglobulin gene in B cells. Machida K. et al., J. Virol. 79: 8079-8089, 2005, PMCID: 1143751
- Lymphoproliferation: Machida K., Tsukiyama-Kohara K., Seike E., Tone S., Shibasaki F., Shimizu M., HCV+cancer: Hayashi Y., Tobita Y., Shimizu, M., Takahashi, H., Taya C., Yonekawa H., Tanaka, N., Kohara M. Disruption of IFN signaling and HCV synergistically enhance lymphoproliferation through type II CD95 and interleukins, Gastroenterology, 137, 285-296, 2009, PMCID: 4197798