No abstract

Recent focus on cancer immunotherapies has led to significant interest in the development of therapeutic strategies that can lead to immunogenic cell death (ICD), which can cause activation of an immune response against tumor cells and improve immunotherapy outcomes by enhancing the immunogenicity of the tumor microenvironment. In this work, a nanomedicine-mediated combination therapy is used to deliver the ICD inducers doxorubicin (Dox), a chemotherapeutic agent, and indocyanine green (ICG), a photothermal agent. These agents are loaded into nanoparticles (NPs) of bovine serum albumin (BSA) that are prepared through a desolvation process. The formulation of BSA NPs is optimized to achieve NPs of 102.6 nm in size and loadings of 8.55 % and 5.69 % (w/w) for ICG and Dox, respectively. The controlled release of these agents from the BSA NPs is confirmed. Upon laser irradiation for 2.5 min, NPs at a dose of 62.5 𝝁g mL −1 are able to increase the temperature of the cells by 7 °C and thereby inhibit the growth of B16F10 melanoma cells in vitro. Surface presentation of heat shock proteins and calreticulin from the cells after treatment confirmed the ability of the Dox/ICG loaded BSA NPs to induce ICD in the melanoma cells.

The Xiphophorus melanoma receptor kinase gene, xmrk, is a bona fide oncogene driving melanocyte tumorigenesis of Xiphophorus fish. When ectopically expressed in medaka, it not only induces development of several pigment cell tumor types in different strains of medaka, but also induces different tumor types within the same animal, suggesting its oncogenic activity has a transcriptomic background effect. Although the central pathways that xmrk utilizes to lead to melanomagenesis are well documented, genes and genetic pathways that modulate the oncogenic effect, and alter the course of disease have not been studied so far. To understand how the genetic networks between different histocytes of xmrk-driven tumors are composed, we isolated two types of tumors, melanoma and xanthoerythrophoroma, from the same xmrk transgenic medaka individuals, established the transcriptional profiles of both xmrk-driven tumors, and compared (1) genes that are co-expressed with xmrk in both tumor types, and (2) differentially expressed genes and their associated molecular functions, between the two tumor types. Transcriptomic comparisons between the two tumor types show melanoma and xanthoerythrophoroma are characterized by transcriptional features representing varied functions, indicating distinct molecular interactions between the driving oncogene and the cell type-specific transcriptomes. Melanoma tumors exhibited gene signatures that are relevant to proliferation and invasion while xanthoerythrophoroma tumors are characterized by expression profiles related metabolism and DNA repair. We conclude the transcriptomic backgrounds, exemplified by cell-type specific genes that are downstream of xmrk effected signaling pathways, contribute the potential to change the course of tumor development and may affect overall tumor outcomes.

Background: Medulloblastoma (MB) is the most common malignant brain cancer in children. Despite the progress made in treating MB, the 5-year survival rate for high-risk tumors remains poor and risk of recurrence within 2 years of treatment is still high. Almost all MB deaths are attributed to leptomeningeal dissemination (LMD) as MB spreads exclusively through cerebrospinal fluid (CSF) to spinal and intracranial leptomeninges. Unfortunately, patients who do survive have reduced quality of life because of the highly toxic side effects of radiation and chemotherapy. Those facts underline the importance of identifying new drivers of medulloblastoma and understanding the mechanism by which those drivers may promote medulloblastoma. Towards that goal, I aim to identify novel drivers of MB and characterize novel therapies for treating (LMD-MB). Using an unbiased genome-wide screen, we discovered THO complex as one of the highly differentially expressed genes that may provide survival advantage to MB cells. THO is a subcomplex of the TREX complex, is known to couple mRNA transcription, processing and nuclear export associated with spliced mRNA. Methods: Recent work in our lab utilizing various genomes and proteomics identified THO complex as a possible target. Transfection agents were used to knockdown part of the TREX subcomplex expression in several MB cells. Western blot and qPCR verified the knockdown. The cell viability was measured using Cell Titer Glo, and cell proliferation was evaluated with an IncuCyte. Cells were seeded at a low density and cultured until colonies formed then were fixed and stained with crystal violet. In addition, cells were seeded in a serum-free medium and allowed to migrate to complete media before being fixed and stained. Flow cytometry was used to examine cells for apoptosis and cell cycle. For apoptosis, cells were stained with propidium iodide (PI) and Annexin FTIC, and for the cell cycle, cells were stained and followed by PI. Results: The Cancer Dependency Map (Dep-Map) meta-analysis revealed that MB strongly depends on The TREX subcomplex. Significantly, increased THO complex expression was associated with a worse overall survival rate in MB patients. Our findings indicated that part of the TREX subcomplex depletion decreased MB cell survival in the short- and long-term proliferation, migration, and invasion. Furthermore, part of TREX subcomplex depletion promoted apoptosis in MB cells. I propose that THO complex may be a new driver of MB and that strategies aiming to reduce part of TREX subcomplex levels and activity might benefit MB patients. Conclusion: TREX subcomplex parts depletion has been demonstrated to reduce MB cells in vitro in various experiments. Future research, including CRISPR-CAS9-based knockout models, single-cell sequencing, and metabolomics, will further elucidate the mechanism(s) and utility of the TREX subcomplex axis in LMD-MB. Citation Format: Shahad M. Abdulsahib, Santosh Timilsina, Manjeet Rao. Identifying the role of novel driver TREX subcomplex in medulloblastoma growth and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6735.