# Establishment and Characterisation of Two Canine Prostate Cancer Cell Lines with Stem Cell Marker Expression

## TL;DR

Researchers created two new cell models from aggressive canine prostate cancer to study its biology and improve treatments for both dogs and humans.

## Contribution

The novel contribution is the establishment and characterization of two canine prostate cancer cell lines with preserved stem cell markers.

## Key findings

- The cell lines retained key epithelial markers and stem cell features from the original tumors.
- Xenografts generated from one cell line recapitulated the histopathological features of the primary tumor.
- Selective loss of certain stem-like populations was observed during in vitro culture.

## Abstract

Prostate cancer in dogs is uncommon but very aggressive, and it is often diagnosed late when treatment options are limited. This makes it difficult to study and to improve outcomes for affected animals. Some cancer cells, often called “stem-like” cancer cells, are thought to play a key role in how cancers grow, spread, and resist treatment. In this study, we developed two new laboratory-grown cell models from naturally occurring prostate cancers in dogs. We carefully compared these cells with the original tumours they came from, and with tumours created in mice using the cells, to see how closely they matched. We found that the new models kept many important features of the original cancers, including markers linked to aggressive behaviour and treatment resistance, although some features were lost when the cells were grown in the laboratory. These results show that our new models are reliable tools for studying prostate cancer in dogs. In the future, they may help researchers to better understand how this disease develops and spreads and support the development of improved treatments for both dogs and people with prostate cancer.

Canine prostatic adenocarcinoma is a rare but highly aggressive cancer that is typically diagnosed at an advanced stage, due to the lack of effective screening methods and poor recognition of early lesions. Cancer stem cells are known to drive tumour progression and treatment resistance in human prostate cancer, but their role in naturally occurring canine disease remains poorly defined. A deeper understanding of the biology of canine prostatic adenocarcinoma is therefore essential to improve prognosis and to develop relevant comparative models. We established and comprehensively characterised two novel canine prostatic adenocarcinoma cell lines, Kodiak and Bobby, with detailed comparison to their tumours of origin and, for Kodiak, xenografts generated in immunodeficient mice. Both lines displayed variable epithelial morphology influenced by culture conditions, and Kodiak xenografts recapitulated key histopathological patterns of the primary tumour. Expression of the luminal epithelial marker CK8/18 and the basal marker CK14 was largely retained across tumour, cell line, and xenograft, whereas the basal markers CK5 and p63, and the urothelial marker UPIII, were diminished or lost during in vitro culture. Evaluation of cancer stem cell-associated markers showed consistent expression of CD44, Nanog, Oct3/4, and Sox2 in the original tumours and cell lines, while CD133, Nestin, and Trop2 were present in the tumours but absent in vitro, indicating selective loss of specific stem-like populations. Media-dependent plasticity was evident in the Bobby line. These models retain key epithelial and stemness features and provide robust platforms for translational prostate cancer research in dogs and humans.