# Mechanical Stimuli‐Induced Manipulation of Malignant Behavior in Bioprinted Cancer Microtissues via PI3K/NF‐κB Activation

## TL;DR

This study shows how mechanical stiffness in the tumor environment activates cancer signaling pathways, leading to drug resistance and aggressive cancer traits.

## Contribution

A novel bioprinting platform with tunable stiffness reveals how mechanical stress activates PI3K/NF-κB signaling in prostate cancer.

## Key findings

- Increased matrix stiffness promotes EMT, stemness, and drug resistance in prostate cancer spheroids.
- Transcriptomic analysis shows PI3K pathway activation under mechanical stress.
- PI3K inhibition reduces NF-κB activation and improves chemotherapy effectiveness.

## Abstract

Increased matrix stiffness within tumor microenvironments (TMEs) significantly influences cancer progression and gene expression, contributing to drug resistance and poor clinical outcomes. Studies demonstrate a strong correlation between nuclear factor kappa B (NF‐κB) upregulation and prostate cancer malignancy. However, the mechanisms by which the mechanical stress within the TME activates NF‐κB remain underexplored. This study developed a prostate cancer spheroid model using an in‐bath 3D bioprinting technique. Cancer spheroids were printed within a bespoke hydrogel bath with tunable stiffness, facilitating the investigation of the relationship between mechanical cues and oncogenic behavior. Increased hydrogel stiffness promoted spheroid compaction, induction of epithelial–mesenchymal transition (EMT) and stemness programs, and elevated drug resistance. Transcriptomic analysis revealed that the phosphoinositide 3‐kinase (PI3K) pathway is most enriched under mechanical stress. Findings demonstrated that increased extracellular matrix stiffness activated PI3K/NF‐κB signaling through mechanotransduction. Pharmacological inhibition of PI3K suppressed NF‐κB nuclear translocation and enhanced chemotherapy efficacy. The bespoke hydrogel effectively recapitulated the mechanical environment of prostate cancer, indicating the pivotal role of PI3K/NF‐κB signaling in regulating prostate cancer malignancy under mechanical stimulation. This suggests a promising therapeutic avenue for improving treatment outcomes.

A mechanically tunable ECM platform is created by integrating dECM–alginate matrices with in‐bath tumor printing. The mechanically tunable ECM environment drives tumors to acquire hypoxia, mechanotransduction signaling, metastatic traits, and drug‐resistant phenotypes that collectively promote malignant transformation. Targeted screening within this platform identifies specific therapeutic responses, demonstrating the platform's utility for evaluating stiffness‐dependent malignancy and drug screening.