Identifying Druggable Genetic Factors Underlying Radiation-induced Heart Disease

PROJECT SUMMARY
Radiotherapy (RT) is a widely utilized treatment in cancer patients. However, RT for thoracic malignancies can
inadvertently harm the heart, resulting in radiation-induced heart diseases (RIHD). Despite the prevalence of
RIHD, the underlying mechanisms are not fully comprehended, and effective therapeutic strategies are lacking.
Existing preclinical studies have hinted at potential protective effects of statins, ACE inhibitors, and antioxidants
against RIHD. However, translating these findings into clinics is hindered by the lack of physiological human
models. Rodent and immortalized cell models are inadequate due to their inability to consider individual genetic
factors contributing to RIHD. Addressing this gap, my proposal leverages the extensive biobank of human
induced pluripotent stem cells (iPSCs) at Stanford, to identify underlie single nucleotide polymorphisms (SNPs)
and causal genes associated with an individual's radio-sensitivity and explore potential protective drugs.
Specifically, (1) in Aim 1, I will establish a cell village comprising 96 iPSC lines to uncover SNPs linked to RIHD.
Cardiomyocytes (CMs) derived from the cell village will be irradiated, simulating damage akin to RIHD, and their
response will be assessed based on gene expression and reactive oxygen-species (ROS) levels. By performing
a cellular Genome-wide association study (GWAS), SNPs associated with individual radiation responses will be
identified. (2) In Aim 2, a high-throughput CRISPR-Cas9 screen will be employed to identify genes responsible
for mediating radiation responses in CMs. (3) In the R00 phase, the research will concentrate on validating SNPs
associated with radiosensitivity and identifying drugs that target genes linked to these SNPs through virtual
screening. The protective effects of these drugs will be tested in 3D engineered heart tissues (EHTs) derived
from iPSCs and in a mouse model of RIHD. The conclusion of this endeavor promises to yield profound insights
into radio-sensitivity, unveil innovative therapeutic candidates, and propose potential countermeasures for RIHD.
This study harmoniously connects with my overarching career goal of establishing myself as an independent
researcher in cardiovascular biology and precision radio-oncology, particularly focusing on mitigating radiation-
induced cardiovascular toxicities. To ensure the triumph of this endeavor and pave the way for my transition to
an independent researcher, my mentor, Dr. Wu, and co-mentor, Dr. Weil, have meticulously devised a tailored
career development plan. This plan seamlessly aligns with my research strategy, allowing me to enhance my
existing research skills, and facilitates the acquisition of novel research expertise, preliminary data, and
additional resources during the K99 phase, propelling me toward autonomy during the R00 phase. With
unwavering support from my esteemed mentoring committee and the conducive environment of the globally
renowned biomedical research center (Stanford School of Medicine), I am confident in receiving exceptional
training that will propel me towards achieving both scientific and career development milestones.

Grant Number: 1K99HL177331-01A1
NIH Institute/Center: NIH
Principal Investigator: Xu Cao