# CTL-killing capacity and cancer stiffness in cancer immunity and therapy

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2022 · $647,366

## Abstract

Project Summary/Abstract: CD8+ T cells (CTLs) mediate protective tumor immunity. The goal of tumor
immune therapy is to engender long-term protective effector T cell immunity and cause tumor eradiation in
patients with cancer. To this end, tumor cells must be receptive and susceptible to CTL-mediated tumor killing.
However, in addition to the quality and quantity of CTLs, what determines tumor cell receptivity to CTL-
mediated tumor killing is poorly understood. It is essential to conduct comprehensive molecular and functional
research on the nature of tumor cell receptivity to CTLs in the human tumor microenvironment.
Tumor biologists have been working on how tumor metabolism enables tumor cell proliferation, survival, and
invasiveness without a comprehensive consideration of the immune involvement. Recent immunological
studies have started to examine how tumor metabolism affects the phenotype and function of different immune
cell subsets in the tumor microenvironment. Yet, how tumor metabolism affects tumor cell receptivity to CTL-
killing is basically unknown. Having established an Optical Tweezers Microscope (OTM) technique and Atomic
Force Microscope (AFM) for cell elasticity and stiffness measurements and applied an airflow-assisted
desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI), we are able to preliminarily
demonstrate that human and mouse breast tumor cells empowered with particular amino acid uptake resulted
in reduced myosin II-mediated contractile activation and tumor cell stiffness. Loss of tumor stiffness led to
tumor cell membrane resistance to perforin drilling force and pore formation by CTLs, resulting in impaired T
cell-mediated tumor killing. Mechanistically, tumor cells were addicted to certain amino acids, including
glutamine, via high expression of SLC6A14, a glutamine transporter. Interestingly, tumor SLC6A14 expression
was controlled by hypoxia. These data reveal previously unknown mechanisms of connection between specific
amino acid metabolism, hypoxia, and T cell immunity in the tumor microenvironment, thereby identifying
cancer glutamine transporter(s) as a potential novel immune metabolic checkpoint target.
Based on these surprising and novel findings, we hypothesize that cancer cell stiffness determines tumor cell
receptivity to CTL-killing, and the interplay between hypoxia and particular amino acid uptake is a novel
immune evasion mechanism in the tumor microenvironment. We propose two specific aims and 8 subaims to
test our central hypothesis that hypoxia targets tumor amino acid transporters, exemplified by SLC6A14, to
alter tumor cell receptivity to CTL-killing and tumor immunity and therapy. Our specific aims are:
Aim 1 is to test our hypothesis that hypoxia metabolically weakens tumor receptivity to CTL-killing.
Aim 2 is to test our hypothesis that hypoxia mechanically weakens tumor receptivity to CTL-killing.

## Key facts

- **NIH application ID:** 10274980
- **Project number:** 1R01CA261985-01
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** WEIPING ZOU
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $647,366
- **Award type:** 1
- **Project period:** 2022-01-07 → 2026-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10274980

## Citation

> US National Institutes of Health, RePORTER application 10274980, CTL-killing capacity and cancer stiffness in cancer immunity and therapy (1R01CA261985-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10274980. Licensed CC0.

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