ORCID
https://orcid.org/0000-0003-4938-7368
Date of Award
2024
Document Type
Dissertation
Degree Name
Philosophy (Ph.D)
Department
Pharmaceutical Sciences
First Advisor
Saurabh Agarwal
Second Advisor
Sue Ford
Third Advisor
Aaron Muth
Abstract
Epigenetic regulators such as Menin and MLL1 drive cancer progression, metastasis, and relapse. MLL1 forms a COMPASS complex with its binding partners, including Menin, to function as an epigenetic enzyme H3K4 methyltransferase. H3K4 methyltransferases are known to promote cancer stem cells' (CSCs) self-renewal capacity and metastasis. CSCs are one of the major causes of tumor relapse and metastasis conditions, ultimately leading to poor overall patient survival. Neuroblastoma (NB) is an extracranial solid tumor that accounts for 8-10% of all pediatric cancers, and approximately 50% of patients display metastasis at the time of diagnosis. In this study, we hypothesized and used a specific small molecule inhibitor, MI-503, to inhibit Menin-MLL1 protein-protein interaction. We observed that MI-503 significantly and in a dose-dependent manner inhibits cell proliferation in multiple NB cells in contrast to the controls in both 2D cell culture and 3D spheroid tumor models. By inhibiting Menin-MLL1 interaction MI-503 not only reduced H3K4 trimethylation but also inhibited several oncogenic cell signaling pathways, as well as genes related to NB CSC survival and growth. Further, MI-503 significantly and dose-dependently induced apoptosis and blocked the cell cycle progression at the S phase in both NB CSCs (CD114+ cells) and non-CSCs (CD114- cells), with a more pronounced effect in NB CSCs. ChIP analysis on the sorted NB CSCs revealed that MI-503 reduced the H3K4 trimethylation at the CSF3R (CD114) gene locus. Additionally, the MEN1 (Menin) knockdown significantly inhibits overall H3K4 trimethylation and CSF3R gene expression, leading to the inhibition of the total NB CSC population and significant inhibition of NB proliferation in 2D and 3D cell culture models. Furthermore, NB xenograft mouse models confirmed that MI-503 significantly inhibits NB tumor growth in vivo by directly inhibiting tumor NB CSCs. Additionally, we found that MI-503 enhanced the chemosensitivity of doxorubicin in in vitro cell culture models. In conclusion, direct targeting of the Menin-MLL1 protein-protein interaction using MI-503 is a promising therapeutic approach for NB and other high-risk cancers. Further developing epigenetic-based therapeutic strategies to target NB CSCs and combining these strategies with current therapies will pave the way for effective treatment modalities for children battling with NB.
Recommended Citation
Chilamakuri, Rameswari, "CHARACTERIZING THE ROLE OF EPIGENETIC REGULATOR MENIN IN PEDIATRIC NEUROBLASTOMA GROWTH USING PRE-CLINICAL MODELS" (2024). Theses and Dissertations. 720.
https://scholar.stjohns.edu/theses_dissertations/720