# Non-epithelial Circulating Tumor Cells Enhance Disease Progression in High-risk Prostate Cancer through EMT and COL1A1 Expression

## TL;DR

This study shows that non-epithelial circulating tumor cells are linked to worse outcomes in high-risk prostate cancer patients, and targeting COL1A1 may help prevent their formation.

## Contribution

The study establishes a cutoff value for non-epithelial CTCs and identifies COL1A1 as a potential therapeutic target in high-risk prostate cancer.

## Key findings

- A cutoff of 45% non-epithelial CTCs was determined as significant for high-risk prostate cancer patients.
- Patients with ≥45% non-epithelial CTCs had shorter progression-free survival and more advanced disease features.
- COL1A1 expression is associated with non-epithelial CTCs through an epithelial-mesenchymal transition mechanism.

## Abstract

Introduction: Circulating tumor cells (CTCs) are important prognostic indicators for malignancies. However, a reliable positive/negative cutoff value of non-epithelial (NE+: hybrid and mesenchymal) CTCs phenotype in prostate cancer (PCa) patients has not been established. Here, we aimed to determine the cutoff value and the prognostic value of NE+ CTCs in high-risk prostate cancer (HRPC) patients after radical prostatectomy (RP).

Methods: The cutoff value of NE+ CTCs was established in spiking experiments, and CTCs were detected in 208 HRPC patients using the CanPatrolTM platform. The expression and function of COL1A1 in PCa were examined via qRT-PCR, Western blot, wound healing assay, Transwell assay, and immunohistochemistry (IHC).

Results: The cutoff value of NE+ CTCs was determined to be 45% by spiking experiments. In 208 HRPC patients, the NE+ CTCs positive group had higher prostate-specific antigen (PSA) levels, more advanced pathological tumor stage, and lymph node stage (P < 0.001, P = 0.002 and 0.002, respectively). Besides, patients with NE+ CTCs ≥ 45% had a shorter median progression-free survival (PFS) than those with NE+ CTCs < 45% (44.5 vs. 51.0 months, hazard ratio = 3.31, P < 0.05). Moreover, we identified that COL1A1 was associated with a high proportion of NE+ CTCs in HRPC patients via an EMT mechanism.

Conclusion: Our findings suggest that NE+ CTCs represent a reliable prognostic indicator for HRPC patients and that targeting COL1A1 may prevent the formation of NE+ CTCs.