2020 — 2021 |
Ngo, Vu Nguyen |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Characterization of Ceacam1 as a Novel Therapeutic in Mantle Cell Lymphoma @ Beckman Research Institute/City of Hope
ABSTRACT Mantle cell lymphoma (MCL), accounting for 6-8% of all non-Hodgkin lymphomas (NHLs), is an aggressive and difficult-to-treat B-cell malignancy. MCL patients have a dismal prognosis with a median overall survival of only 3-5 years owing to frequent relapse and resistance to contemporary chemotherapy. Despite recent treatment advances with the FDA-approved drug ibrutinib, which targets the B-cell receptor (BCR) signaling molecule Bruton?s tyrosine kinase (BTK), one-third of MCL patients are ibrutinib-resistant, and even ibrutinib-sensitive patients eventually acquire resistance to the drug. Patients who are insensitive or progress during ibrutinib treatment have very poor outcomes. Thus, more effective post-ibrutinib treatments are urgently needed. Abnormal BCR signaling plays a key oncogenic signal in MCL, but the underlying mechanism is not known. Using an integrated functional genomics approach combining a genome-wide CRISPR-Cas9 screen and gene expression profiling, our group has uncovered CEACAM1 (carcinoembryonic antigen-related cell adhesion molecule-1) as a potential contributor to BCR hyperactivity in MCL. CEACAM1 is a type 1 transmembrane protein expressed as different isoforms due to alternative splicing in epithelial cells and activated leukocytes. In contrast to the short isoform, the CEACAM1 long isoform possesses a cytoplasmic tail that contains the immunoreceptor tyrosine-based inhibitory motif (ITIM) known to negatively regulate the antigen receptor signaling in T cells. We found that CEACAM1 is overexpressed specifically in MCL, as compared to naïve B cells or other B-cell malignancies. Consistent with our CRISPR screen results, depletion of CEACAM1 is toxic in multiple MCL cell lines, but not in non-MCL lymphoma cells. CEACAM1 depletion also markedly reduced proximal BCR signaling (e.g., SYK phosphorylation) and BCR-mediated Ca2+ signaling. More importantly, using T cells that express the CEACAM1-specific chimeric antigen receptor (CAR), we showed that these CAR T cells could effectively eliminate MCL tumors while sparing non-MCL lymphoma in vitro. On the basis of these findings, we hypothesize that CEACAM1 is essential for the oncogenic BCR signaling in MCL and thus a valid therapeutic target for this malignancy. We will test the hypothesis through accomplishing the following specific aims: 1) Determine the mechanisms underlying CEACAM1-regulated BCR signaling; 2) Characterize the MCL-specific expression of CEACAM1; 3) Develop a CAR T-cell strategy to treat MCL in vivo using pre-clinical patient-derived xenograft (PDX) models. Findings from this proposal will improve our limited knowledge of the role of CEACAM1 in MCL pathogenesis. We anticipate that successful completion of the project will provide relevant pre-clinical data for future studies towards developing a novel, effective therapy for MCL.
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0.913 |
2021 |
Ngo, Vu Nguyen |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
The Role of Ceacam1 in Oncogenic B-Cell Receptor Signaling and Immunotherapy in Mantle Cell Lymphoma @ Beckman Research Institute/City of Hope
Abstract Mantle cell lymphoma (MCL) accounts for 6-8% of all non-Hodgkin lymphomas (NHLs). While substantial therapeutic advances have been achieved for other NHLs, MCL remains an incurable lymphoma, the reason of which is not known. MCL patients have a dismal prognosis with a median overall survival of 3-5 years. Standard of care includes ibrutinib, a small molecule inhibitor of the B-cell receptor (BCR)-proximal tyrosine kinase BTK. However, one-third of MCL patients do not respond to the drug. Even initially ibrutinib- sensitive patients invariably develop resistance; however, the mechanisms of ibrutinib-resistance are now clear. Since mechanistic insight into oncogenic BCR signaling in DLBCL and CLL enabled the development of highly effective treatment approaches, this proposal will address the mechanisms of oncogenic BCR- signaling in MCL. In an integrated functional analysis combining a genome-wide CRISPR-Cas9 library, gene expression profiling and BCR signal transduction studies, we have uncovered CEACAM1 as a central component of oncogenic BCR signaling that is essential in MCL but not in normal B cells or other B-cell malignancies. As a transmembrane protein, CEACAM1 is expressed on the surface of activated lymphocytes and carries two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) on its cytoplasmic tail. Owing to recruitment of the inhibitory phosphatase SHP1 to the ITIMs, CEACAM1 functions as a regulator of T-cell receptor (TCR) signaling in T cells, however, its function in normal B cells and MCL is not known. Unexpectedly, our preliminary data showed that CEACAM1 function induced a net increase of BCR signaling, leading to increased survival and proliferation of MCL cells in vitro and in vivo. Our mechanistic studies revealed that CEACAM1 recruited the actin-binding protein filamin A to the plasma membrane microdomains and activated the BCR-proximal kinase LYN after antigen engagement. Furthermore, super- resolution confocal microscopy revealed that CEACAM1 promoted reorganization of the actin cytoskeletal network following BCR cross-linking. Leveraging the clinical grade Cell Therapeutics Facility at City of Hope, we designed and validated a novel CEACAM1 chimeric antigen receptor (CAR) engineered in primary human T cells. The CAR-T cells were highly active in eliminating CEACAM1+ MCL but lacked reactivity against other cell types. Based on our discovery of CEACAM1 as a critical BCR signaling component in MCL and the successful development of CEACAM1 CAR-T cells, we hypothesize that CEACAM1 functions as a central driver of oncogenic BCR activity and represents a novel therapeutic target in MCL. The following specific aims will test and refine the concept of CEACAM1-based therapies for MCL: Aim 1) Define the mechanistic role of CEACAM1 in oncogenic BCR signaling in MCL; Aim 2) Dissect the role of CEACAM1 in new genetic mouse models for MCL; Aim 3) Validation of CAR T-cell strategies targeting CEACAM1 in refractory MCL. Results from the proposed studies are expected to provide: 1) new information on the central role of CEACAM1 in oncogenic BCR signaling and MCL, and 2) pre-clinical validation of novel immunotherapeutic strategies targeting CEACAM1 in refractory MCL.
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0.913 |