JAN 29, 2021 1:39 PM PST

As Humans Evolved, Cancer Came Along

WRITTEN BY: Carmen Leitch

Humans are far more likely to get several types of cancerous tumors than our closest evolutionary cousins, chimpanzees. Researchers may have now learned more about why that is. The work, which was reported in FASEB BioAdvances, suggests that humans carry a gene that's sometimes expressed but in other cases is not, and that may be related to why we're more prone to advanced carcinoma than chimps. The cancer-related gene is called SIGLEC12, which encodes for a protein that was probably once involved in the immune response.

Image credit: Pxhere

"At some point during human evolution, the SIGLEC12 gene, and more specifically, the Siglec-12 protein it produces as part of the immune system, suffered a mutation that eliminated its ability to distinguish between 'self' and invading microbes, so the body needed to get rid of it," explained the senior study author Ajit Varki, M.D., Distinguished Professor at the University of California (UC) San Diego School of Medicine and Moores Cancer Center.

While most people stopped expressing the gene as a protein, it wasn't removed from the genome, and it seems some people still express a mutated form of the gene.

"But it's not completely gone from the population; it appears that this dysfunctional form of the Siglec-12 protein went rogue and has now become a liability for the minority of people who still produce it," added Varki.

In about 60 to 70 percent of people, the SIGLEC12 gene carries a mutation that stops the full-length protein from being produced. The human SIGLEC-12 gene also carries a mutation that stops it from recognizing its binding partner. It had been assumed to be of little clinical relevance.

In this research, the scientists assessed the Siglec-12 proteins in cancerous and normal tissue samples. They found the Siglec-12 protein in about 30 percent of normal tissue samples, which was expected based on the genetic data. However, a significant majority of the advanced cancerous tissue samples were also found to carry the Siglec-12 protein.

When the researchers investigated tissue samples from a different group of patients that had advanced stage colorectal cancer, they determined that over 80 percent of the tissue samples carried the still-functional version of the SIGLEC-12 gene. These patients with the functional gene also had worse clinical outcomes than the patients that carried a non-functional form of the gene.

"These results suggest that the minority of individuals who can still make the protein are at much greater risk of having an advanced cancer," said study co-leader Nissi Varki a professor of pathology at UC San Diego School of Medicine.

After engineering tumor cells to produce the Siglec-12 protein, the researchers confirmed that the protein made the cancerous cells grow much faster compared to cells that did not make the protein. The production of the protein was also linked to biochemical pathways that are known to be active in active cancers

This work could one day be used to create diagnostic tools that can improve treatments. Varki noted that "we might also be able to use antibodies against Siglec-12 to selectively deliver chemotherapies to tumor cells that carry the dysfunctional protein, without harming non-cancerous cells."

Sources: Science Daily via University of California - San Diego, FASEB BioAdvances

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JAN 10, 2021
Microbiology
Some Bacteria Know the Time
JAN 10, 2021
Some Bacteria Know the Time
People, animals, and even plants are known to have biological clocks, and new work has revealed that free-living bacteri ...
FEB 16, 2021
Clinical & Molecular DX
What Dead Cells Can Tell Us About Our Health
FEB 16, 2021
What Dead Cells Can Tell Us About Our Health
Taking a sample of tissue called a biopsy from an organ suspected of harboring a pathology is a common diagnostic practi ...
MAR 10, 2021
Genetics & Genomics
As Diphtheria Cases Rise & More Become Drug Resistant, It May Become a Threat
MAR 10, 2021
As Diphtheria Cases Rise & More Become Drug Resistant, It May Become a Threat
Diphtheria was once a leading cause of death for children; immunization programs eventually changed that for most countr ...
MAR 21, 2021
Genetics & Genomics
Deciphering How Some Environmental Influences Affect Development
MAR 21, 2021
Deciphering How Some Environmental Influences Affect Development
We know that there are certain substances that can harm a developing fetus, like alcohol or lead. Some health conditions ...
MAR 28, 2021
Cell & Molecular Biology
Understanding How Cold-Induced Tooth Pain Happens
MAR 28, 2021
Understanding How Cold-Induced Tooth Pain Happens
Our teeth do a lot of work, and they may become sensitive to cold as the gums erode due to aging or because they have an ...
APR 07, 2021
Genetics & Genomics
New Approach Reveals 13 Novel Alzheimer's-Linked Genes
APR 07, 2021
New Approach Reveals 13 Novel Alzheimer's-Linked Genes
Scientists have been using genetic and computational tools to find small changes in the sequences of genes that are like ...
Loading Comments...