PROJECT SUMMARY/ABSTRACT
Despite being thoroughly characterized, glioblastoma multiforme (GBM) remains one of the most common
malignant primary brain tumors. Currently, patient prognosis has remained poor in that treatment for GBM has
only moderately improved survival rates and quality of life even with the employment of aggressive multimodal
therapies. The unique heterogeneous genetic, epigenetic, and microenvironmental features of GBM and the
brain make tumors resistant to treatments that have otherwise been highly effective in treating cancers of other
tissues. In particular, GBM contains cancer stem cells, termed glioblastoma stem cells (GSCs), that are self-
renewing and tumorigenic, thereby supporting the progression and growth of the primary tumor even after
surgical resection. GSCs have the ability to actively remodel the tumor microenvironment and receive
maintenance cues from their surroundings. In recent published studies from our laboratory, GSCs have been
found to display unique circadian rhythms and dependence on core circadian clock transcription factors, Brain
and Muscle ARNT-Like 1 (BMAL1), otherwise known as Aryl Hydrocarbon Receptor Nuclear Translocator Like
(ARNTL), and Circadian Locomotor Output Cycles Kaput (CLOCK). This dependence was not observed in
normal neural cells nor differentiated glioblastoma cells (DGCs) and is consistent with associations between the
circadian rhythm and increased likelihood of tumor development. Loss of BMAL1 or CLOCK in GSCs induced
cell cycle arrest, apoptosis, attenuation of mitochondrial metabolic function, and reduced expression of the
tricarboxylic acid (TCA) cycle enzymes and stemness genes, such SOX2, OLIG2, and MYC. Additionally, novel
small molecule agonists and stabilizers of two independent negative core clock regulators, Cryptochrome 1/2
(CRY1/2) and REV-ERBa/b (REV-ERBs), were found to be able to downregulate stem cell regulators and reduce
GSC growth. In this study, I intend to elucidate the mechanisms in which epigenetic machineries, in particular
protein arginine methyl transferases (PRMTs), regulate transcription of circadian clock oscillators to promote
stemness and proliferation abilities of GSCs. I also aim to determine the efficacy of small molecule CRY
stabilizers and REV-ERB agonists, both independently and in combination with each other, in targeting GSCs
as novel GBM therapies. My findings will illuminate the epigenetic regulation of circadian clock components in
the context of GSC maintenance and progress a preclinical model for GBM treatment via pharmacological
targeting of the circadian clock.