How a Human Cancer Breakthrough Could Shape the Future of Veterinary Oncology

Colorectal cancer remains one of the most lethal malignancies worldwide and ranks second in global cancer mortality. In 2020 alone, more than 900,000 people died from the disease. While early detection dramatically improves outcomes, metastatic progression continues to drive poor prognoses, with five year survival rates dropping below 10 percent once the cancer spreads.

A new study led by Christopher J. Lengner and M. Andrés Blanco at the University of Pennsylvania School of Veterinary Medicine offers a significant advance in our understanding of metastasis. Using high throughput CRISPR based screening in a tumor organoid model, the team has identified two bona fide metastasis suppressor genes: Ctnna1 and Bcl2l13. Their work, published in the Proceedings of the National Academy of Sciences, showcases a methodological leap that has the potential to influence both human and veterinary cancer research.

A powerful screening approach

The investigators used a CRISPR knockout library targeting approximately 1,500 genes broadly associated with cancer biology. By systematically disrupting each gene, they assessed its influence on metastatic behavior in a preclinical model. Blanco describes the process as equivalent to scanning every strand of hay in a haystack to find the one needle that matters. Traditionally, CRISPR screens have relied heavily on tumor cell lines. Although informative, these models often fail to accurately reflect the behavior of primary human cancers and rarely replicate metastatic conditions. Cancer research as a whole has been shifting toward organoid and in vivo systems to improve translational relevance.

The team took an innovative hybrid approach. They introduced targeted mutations into a colon tumoroid containing hallmark human colorectal cancer driver mutations, then transplanted the tumoroid into its native tissue environment. This allowed the researchers to monitor both primary tumor behavior and metastatic spread in vivo. Very few studies combine organoids and in vivo screening, and even fewer have applied this method to colorectal cancer metastasis.

What the suppressor genes do

Ctnna1 (alpha catenin) plays a critical role in cell adhesion. Loss of Ctnna1 disrupts cell to cell contact, enabling cells to migrate and invade surrounding tissue. This aligns with established metastasis mechanisms where reduced adhesion promotes cellular dissemination.

Bcl2l13 (BCL Rambo) regulates a form of programmed cell death that occurs when epithelial cells detach from their native environment. In healthy tissue, this prevents displaced cells from surviving in the wrong anatomical location. In colorectal cancer, suppression of Bcl2l13 may allow metastatic cells to survive after leaving the primary tumor.

These findings highlight two distinct but complementary barriers to metastasis: maintaining appropriate cell adhesion and enforcing cell death when cells deviate from their epithelial context.

Implications for veterinary oncology

While colorectal cancer is relatively uncommon in companion animals, the underlying biological principles of metastasis are shared across many tumor types seen in veterinary practice, including osteosarcoma, mammary carcinoma, hemangiosarcoma and melanoma. The study’s methodological advancements carry particular relevance for veterinary oncology:

1. Organoid based models may enhance translational cancer research.
Organoids derived from canine or feline tumors are already being explored in academic settings. Combining organoids with in vivo screening could accelerate the identification of therapeutic targets relevant to veterinary patients.

2. Metastasis suppressor genes may inform prognostics.
As sequencing becomes more accessible in veterinary medicine, identifying patterns of gene loss or suppression could refine risk stratification for high metastasis cancers.

3. Cross species insights strengthen comparative oncology.
Discoveries in human cancer biology often inform veterinary practice and vice versa. Understanding fundamental mechanisms of metastasis supports development of shared diagnostic and therapeutic innovations.

The research team plans to conduct complementary CRISPR activation screens to identify genes that actively promote metastasis. These pro metastatic targets are especially relevant for drug development, both in human and veterinary applications. According to the authors, the methodology is now established, and the platform is ready for larger scale investigation. For veterinary professionals, this study underscores the continued importance of comparative oncology and the power of advanced genetic tools. As organoid technology expands and CRISPR based screening becomes more accessible, the insights gained from these methods may ultimately translate into improved outcomes for the animal patients we serve.