Cancer cells boost biosynthesis and energy metabolism to enable growth and proliferation. The
autophagy-lysosomal system degrades intracellular proteins and organelles, particularly under nutrientdeprivation
conditions, providing energy and metabolites for cell survival and proliferation. Eileen White’s
pioneering work in mice shows that acute ablation of Atg7, an essential autophagy gene, blocked tumor growth
and promoted tumor cell death in pre-existing KrasG12D-frt/+;Trp53frt/frt non-small cell lung cancer. Thus,
metabolism modulation via acute inhibition of the autophagy-lysosomal system may provide a novel cancer
therapeutic strategy. Ceroid lipofuscinosis, neuronal 3 (CLN3) is a component of the autophagy protein-protein
interaction network. Homozygous deletion of 1 kb genomic sequence within the CLN3 gene leads to lysosomal
storage disease and is the predominant cause for juvenile neuronal ceroid lipofuscinosis. Our preliminary data
show overexpression of CLN3 in breast cancer including all subtypes, and that CLN3 deficiency leads to
impaired cell proliferation and profound metabolic defects including the serine and one-carbon metabolism.
Here we propose to investigate the roles of CLN3 in breast cancer metabolism in two aims: In Aim 1, we will
test the hypothesis that CLN3 promotes cancer cell proliferation through enhancing serine and onecarbon
metabolism. In Aim 2, we will test the hypothesis that CLN3 maintains the serine and one-carbon
metabolite pools via (A) activation of the amino acid sensing mTORC1 pathway and (B) a direct
pathway involving CLN3-PHGDH binding (Aim 2). We expect that our work will shed light on important roles
of CLN3 in breast cancer metabolism and tumor growth/metastasis, facilitating ultimate discovery of novel
therapeutic strategies via modulating cancer metabolism by targeting CLN3 and autophagy-lysosomal system.
The work performed under this award will be used to generate a NCI R01 proposal: The acquired data
will help 1) generate preliminary data (e.g., SIRM analysis of CLN3-deficient vs. proficient breast cancer cells)
for the R01 proposal; 2) further focus the R01 proposal, e.g., on mTORC1-dependent and/or independent
mechanisms; 3) generate critical reagents, e.g., CLN3-deficient breast cancer mouse models.