Cancer Cells Create Acidic Barrier to Evade Immune System

Cancer cells survive and thrive because they know how to combat our immune systems. There are reportedly three ways they interact with our immune system, and a new study examined one of their techniques.

Cancer Cells Build Acidic Wall as Barrier To Evade Immune System

Cancer cells have three main ways of interacting with our immune systems -- hide, fight back, or build a physical barrier. In a new study, researchers from the University of Texas Southwestern investigated the third one.

Tumors have long been known to have a somewhat higher acidity than normal human tissue. Their synthesis of lactic acid, a waste product of the cells' metabolism, is mostly to blame. This acidity varies throughout cancer cells, though.

The study measured pH variations in tumor cells using nanoscale probes by Jinming Gao and his colleagues at UT Southwestern. They discovered that one side of the cells had a noticeably higher acidity. Put otherwise, the acidity was distributed unevenly among the cells.

Upon examining complete tumor tissues, the researchers discovered that the cancerous cells dispersed their acid into the surrounding milieu, generating an elevated acidity barrier around the tumor's edge.

By examining samples from human tumor tissue, the researchers discovered that this wall of heightened acidity was essentially devoid of the killer T cells that our bodies need to fend off viruses and other dangerous cell types. Put differently, the cancer fortified itself against the immune system by forming an acid wall.

"This study revealed a previously unrecognized polarized extracellular acidity that is prevalent around cancer cells," Gao explained.

These findings may impact the creation of anti-cancer medications. First, knowing how acidic the environment is around cancer cells may aid in the creation of cancer medicines that are specifically tailored to the location of tumors to deliver their active components. In this instance, the malignant tissue may use the elevated acidity as a signal to ensure the medication is exclusively administered to the tumor site.

As our knowledge of this process advances, we might also be able to create medications that stop cancer cells from forming acid walls, leaving them more susceptible to immune system assault.

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How Do Cancer Cells Behave in an Acidic Environment?

MIT researchers looked into cancer cells linked to an acidic environment. A separate study found that tumors have pockets of high acidity within them where only a little oxygen is available.

They learned that tumor cells can easily produce proteins that make them even more aggressive in an acidic environment. The researchers demonstrated how they might stop this process in mice by lowering the acidity of the tumor environment.

"Our findings reinforce the view that tumor acidification is an important driver of aggressive tumor phenotypes, and it indicates that methods that target this acidity could be of value therapeutically," said Frank Gertler, an MIT professor of biology, a member of MIT's Koch Institute for Integrative Cancer Research, and the senior author of the study.