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Hartman-Houstman H, Swenson S, Minea RO, Sinha UK, Chiang MF, Chen TC, Schönthal AH. Activation of Epstein-Barr Virus' Lytic Cycle in Nasopharyngeal Carcinoma Cells by NEO212, a Conjugate of Perillyl Alcohol and Temozolomide. Cancers (Basel) 2024; 16:936. [PMID: 38473298 DOI: 10.3390/cancers16050936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 01/27/2024] [Accepted: 02/14/2024] [Indexed: 03/14/2024] Open
Abstract
The Epstein-Barr virus (EBV) is accepted as a primary risk factor for certain nasopharyngeal carcinoma (NPC) subtypes, where the virus persists in a latent stage which is thought to contribute to tumorigenesis. Current treatments are sub-optimal, and recurrence occurs in many cases. An alternative therapeutic concept is aimed at triggering the lytic cycle of EBV selectively in tumor cells as a means to add clinical benefit. While compounds able to stimulate the lytic cascade have been identified, their clinical application so far has been limited. We are developing a novel anticancer molecule, NEO212, that was generated by covalent conjugation of the alkylating agent temozolomide (TMZ) to the naturally occurring monoterpene perillyl alcohol (POH). In the current study, we investigated its potential to trigger the lytic cycle of EBV in NPC cells in vitro and in vivo. We used the established C666.1 cell line and primary patient cells derived from the brain metastasis of a patient with NPC, both of which harbored latent EBV. Upon treatment with NEO212, there was an increase in EBV proteins Zta and Ea-D, key markers of the lytic cycle, along with increased levels of CCAAT/enhancer-binding protein homologous protein (CHOP), a marker of endoplasmic reticulum (ER) stress, followed by the activation of caspases. These effects could also be confirmed in tumor tissue from mice implanted with C666.1 cells. Towards a mechanistic understanding of these events, we used siRNA-mediated knockdown of CHOP and inclusion of anti-oxidant compounds. Both approaches blocked lytic cycle induction by NEO212. Therefore, we established a sequence of events, where NEO212 caused reactive oxygen species (ROS) production, which triggered ER stress and elevated the levels of CHOP, which was required to stimulate the lytic cascade of EBV. Inclusion of the antiviral agent ganciclovir synergistically enhanced the cytotoxic impact of NEO212, pointing to a potential combination treatment for EBV-positive cancers which should be explored further. Overall, our study establishes NEO212 as a novel agent able to stimulate EBV's lytic cycle in NPC tumors, with implications for other virus-associated cancers.
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Affiliation(s)
- Hannah Hartman-Houstman
- Department of Molecular Microbiology & Immunology, Keck School of Medicine, University of Southern California (USC), Los Angeles, CA 90089, USA
| | - Steve Swenson
- Department of Neurosurgery, Keck School of Medicine, USC, Los Angeles, CA 90089, USA
| | - Radu O Minea
- Department of Neurosurgery, Keck School of Medicine, USC, Los Angeles, CA 90089, USA
- USC/Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA
| | - Uttam K Sinha
- USC/Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA
- Department of Otolaryngology, Keck School of Medicine, USC, Los Angeles, CA 90089, USA
| | - Ming-Fu Chiang
- Department of Neurosurgery, Fu Jen Catholic University Hospital, New Taipei City 24352, Taiwan
| | - Thomas C Chen
- Department of Neurosurgery, Keck School of Medicine, USC, Los Angeles, CA 90089, USA
- USC/Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA
- NeOnc Technologies, Inc., Los Angeles, CA 90069, USA
| | - Axel H Schönthal
- Department of Molecular Microbiology & Immunology, Keck School of Medicine, University of Southern California (USC), Los Angeles, CA 90089, USA
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