Page 47 - Hormel Institute Annual Report 2021-22

AML1-ETO+ (AE+) AML
Additional High HIF1a + AE + mutations Low HIF1a (e.g., FLT3-ITD)
Low DNMT3a
HIF1a
AE DNMT3a ? X TSGs
and m6A are significantly increased when normalized to the colony sizes from ultimate resistant population. These findings imply that m6A dynamically facilitates an evolutionary shift in the population to a drug-resis- tant state during treatment. The ongoing and future studies are to determine: i) whether and how the dynamics of m6A alterations allow resistant clones
to outcompete therapy-sensitive clones throughout the chronic drug selection course; ii) whether and how the FTO-m6A axis promotes and sustains TKI resis- tance in vivo; iii) whether and how pharmacological targeting of FTO inhibits TKI resistance development and impairs resistant leukemia growth; and iv) how FTO aberrations regulate resistance-sustaining genes in leuFkiegmureia1cells. Findings will broaden the molecular understanding of cancer cell fitness and evolution under drug selection, and advance the application of novel “RNA epitranscriptomic drugs” in preventing and killing resistant cancer cells.
Studies on the use of RNA nanotechnology to deliver siRNAs/small molecule inhibitors to overcome resistance to molecular- targeted therapies
Off-target uptake and low efficient delivery of thera- peutic agents lead to unwanted adverse effects in vivo, especially in leukemia therapy, where few targets are available to guide drug delivery. A promising approach to these problems would be the use of novel nano- carriers (e.g., RNA nanoparticles) and new cell sur- face markers for targeted delivery of new therapeutic agents to resistant leukemia cells. Our goals are i) to develop novel RNA nanoparticles conjugated with RNA
| 47 We have successfully constructed RNA nanoparti-
cles with/without exosomes, which contain phi29pR- NA-3WJ as a core, anti-miR21 or survivin siRNA and RNA aptamers targeting cancer cell surface markers (e.g., CD133). These RNase resistant and thermo- dynamically stable RNA nanoparticles block tumor growth in in vivo models without obvious toxicity. Biodistribution results show that CD133-targeted RNA nanoparticles accumulate mainly in tumors expressing CD133, but not in other vital organs. Given CD133 upregulation in resistant cells, we made RNA nanoparticles displaying CD133 RNA aptamer, and evidenced a strong cellular uptake by resistant cells. Therefore, we hypothesize that deactivation of FTO gene may eradicate TKI resistant cells, and that the therapeutic effects of targeting FTO may be further enhanced when FTO siRNAs are delivered by CD133 targeting RNA nanoparticles (Figure 2). We anticipate that our proposed studies will have a major impact
in the field by shifting the theoretical paradigm of understanding and treating drug resistant cancer, and by developing a new nanocarrier for resistant cancer-targeted drug delivery. The findings will also significantly advance the design and application of RNA nanotechnology in cancers.
Recent Publications:
• Mueller, S., Dennison, G., & Liu, S. (2021). An Assessment on Ethanol-Blended Gasoline/ Diesel Fuels on Cancer Risk and Mortality. Int J Environ Res Public Health, 18(13), 6930.
• Wang, H., Liu, Y. C., Zhu, C. Y., Yan, F., Wang, M. Z., Chen, X. S., Wang, X. K., Pang, B. X.,
Li, Y. H., Liu, D. H., Gao, C. J.*, Liu, S. J.*, & Dou, L. P.* (2020). Chidamide increases the sensitivity of refractory or relapsed acute myeloid leukemia cells to anthracyclines via regulation of the HDAC3 -AKT-P21-CDK2 signaling pathway. J Exp Clin Cancer Res, 39(1), 278. (*Corresponding author.)
ORCID iD: 0000-0002-2605-8089
Tumor suppressors Good prognosis (TSGs)
Poor prognosis
Schematic model illustrating the possible roles of the HIF1a-DNMT3a axis in a subgroup of AE+ AML. Red lines indicate the focus of this project.
Studies on the role of RNA m6A aberrations
in protein kinase-targeted cancer therapy
The m6A is the most common internal modification
in RNAs, and the fat mass and obesity-associated protein (FTO) is a major m6A demethylase. Tyrosine kinase inhibitors (TKIs) have been used to treat chronic myeloid leukemia (CML), achieving highly effective responses. However, these TKI therapies typically provide only short-term relief due to disease progres- sion and recurrence with largely unknown mecha- nisms. We showed that untreated (naïve), genetically (in terms of BCR/ABL) uniform leukemia cells are high- ly heterogeneous in the levels of FTO and m6A. This epigenetic heterogeneity is associated with variations in cell growth rates and clone sizes; clones with larger sizes have higher FTO expression and lower m6A, and they display higher TKI tolerance than smaller clones. Upon long-term exposure to TKIs, the levels of FTO
a Construction and assembly of fluorescent CD133apt/3WJ/cholesterol
C3wj-CD133apt
b Assembly mechanisms for ligand-displaying EVs
FTO siRNA cargo loading
CD133apt/3WJ/cholesterol arrowtail
Design of the native EVs decorated by RNA nanotechnology. a, Two-dimensional structure for 3WJ assembly. b, EV loading and RNA aptamer display. EVs, extracellular vesicles.
aptamer of surface marker CD133 (highly expressed in resistant cells) to specifically deliver the fat mass and obesity-associated protein FTO (a TKI resistant gene) siRNAs for eradicating resistant cells, and ii) to decipher the molecular mech- anisms underlying RNA nano- particle-antileukemia activities.