# Metabolic enzyme PFKFB3 mediates matrix stiffness‐potentiated tumour growth and radiotherapeutic resistance in HCC

## TL;DR

This study shows how stiff liver tissue promotes HCC tumor growth and resistance to radiation therapy by affecting a key metabolic enzyme called PFKFB3.

## Contribution

The study identifies a novel nonmetabolic role of PFKFB3 in DNA repair and reveals a stiffness-triggered pathway that enhances HCC growth and radiotherapy resistance.

## Key findings

- High matrix stiffness increases HCC cell proliferation and DNA repair by upregulating PFKFB3 expression.
- Matrix stiffness suppresses PFKFB3 ubiquitination via downregulating E3 ubiquitin ligase NEDD4, enhancing glycolysis.
- PFKFB3 nuclear translocation and interaction with Ku70 strengthens DNA damage repair in irradiated HCC cells.

## Abstract

Although the contribution of matrix stiffness to aggravating the malignant features of HCC cells has been well documented, the effects of matrix stiffness on chemoradiotherapy resistance and its underlying mechanism remain largely elusive.

To delineate the role of matrix stiffness in HCC progression, we engineered novel in vivo animal models with defined liver stiffness and a complementary tunable hydrogel culture system. This integrated approach enabled a comprehensive investigation into how biomechanical cues modulate HCC cell proliferation and DNA repair both in vitro and in vivo.

High stiffness stimulation noticeably enhanced cell proliferation and cell survival from DNA damage through changing the expression and distribution of metabolic enzyme PFKFB3. Specifically, high stiffness stimulation prominently suppressed PFKFB3 ubiquitination by downregulating E3 ubiquitin ligase NEDD4, and then increased the stability of PFKFB3 protein to enhance glycolysis, ultimately promoted HCC growth. Meanwhile, high matrix stiffness stimulation also effectively strengthened the DNA damage repair ability of irradiated HCC cells, and PFKFB3 nuclear translocation mediated in matrix stiffness‐regulated DNA damage repair by interacting with Ku70.

Our results delineate a PFKFB3‐mediated pathway that underpins how increased matrix stiffness potentiates HCC growth and compromises radiotherapy efficacy. These findings not only highlight the contribution of matrix stiffness to tumor growth and DNA damage repair in HCC, but also disclose a previously unidentified nonmetabolic function of PFKFB3.

Increased matrix stiffness significantly promoted glycolysis in HCC cells via upregulating PFKFB3 expression.High stiffness stimulation suppressed PFKFB3 ubiquitination by downregulating E3 ubiquitin ligase NEDD4 expression.PFKFB3 participated in DNA damage repair by translocating into nuclear and interacting with Ku70, which strengthened by matrix stiffness.

Increased matrix stiffness significantly promoted glycolysis in HCC cells via upregulating PFKFB3 expression.

High stiffness stimulation suppressed PFKFB3 ubiquitination by downregulating E3 ubiquitin ligase NEDD4 expression.

PFKFB3 participated in DNA damage repair by translocating into nuclear and interacting with Ku70, which strengthened by matrix stiffness.

This study proposes a stiffness‐triggered pathway that co‐opts PFKFB3 expression and localization to fuel HCC growth and compromise radiotherapy efficacy. Specifically, matrix stiffness suppresses PFKFB3 ubiquitination by downregulating E3 ubiquitin ligase NEDD4 expression, and then enhances the stablity of PFKFB3 protein to increase glycolysis. Simultaneously, matrix stiffness strengthens the DNA damage repair ability of irradiated HCC cells through PFKFB3 nuclear translocation and interacting with Ku70.