7. Project Summary/Abstract
Altered metabolism is a nearly universal characteristic of cancer cells, which require metabolic
adaptations to support proliferation and survival. However, mechanisms that dictate the diverse metabolic
liabilities and phenotypes of cancer remain poorly understood. Thus, the resurgence of interest to target cancer
metabolism for patient benefit will require an improved understanding of metabolic regulation and requirements
in malignant cell types. Cells in culture are commonly used to study cancer metabolism and to develop drugs
that exploit metabolic vulnerabilities. However, while it is increasingly appreciated that environmental factors
impact cell metabolism, our current understanding of metabolic rewiring in cancer is largely based on findings
from cells cultured in media that poorly reflect the metabolic composition of human plasma. Therefore, our
overarching hypothesis is that many important aspects of cancer cell metabolism have been overlooked or
misconstrued as a consequence of utilizing model systems that inadequately resemble physiologic conditions.
To begin to test this, we developed a new culture medium (human plasma-like medium; HPLM) that contains
polar metabolites and salts at concentrations comparable to those of adult human plasma. We then showed
that, relative to traditional media, HPLM has widespread and largely unexplained effects on cell metabolism.
Our preliminary data reveal that, when cultured in traditional media, certain cell lines secrete alanine,
but that in HPLM, those cells instead consume alanine at rates exceeding those for most other amino acids.
Therefore, we will test the hypothesis that alanine has a key role for cells cultured in physiologic conditions
(Aim 1). Using a chemostat technology that we developed, we will also determine how the removal of alanine
from HPLM affects the growth of over 40 barcoded blood cancer cell lines in a pooled fashion. In addition,
through the use of CRISPR-based loss-of-function screens, we identified NME6, a gene that encodes a poorly
studied mitochondrial protein, as conditional lethal with HPLM. Thus, we will also test the hypothesis that
NME6 serves a critical and unforeseen role in mitochondrial homeostasis for cells cultured in physiologic
conditions (Aim 2). Lastly, we also found that HPLM dramatically influences cell sensitivity to the cancer drug
5-fluorouracil without affecting the potency of doxorubicin, another common chemotherapeutic. Therefore,
using a library of > 1,900 diverse oncology-related small molecules, we will perform a high-throughput screen
to test the hypothesis that, relative to traditional media, HPLM alters the potency of additional compounds. We
will then pursue validation and mechanistic insights for differential drug phenotypes in cell line and primary cell
models (Aim 3). Our proposed work uses distinct approaches to better understand how environmental factors
that more closely reflect physiologic conditions impact the metabolism of blood cancer cells, and has the
potential to not only identify unforeseen biological insights, but to also uncover new therapeutic targets and
approaches that may have greater in vivo relevance for cancer therapy.