# EZH2-Mediated PTEN Silencing Promotes AKT-Dependent Afatinib Resistance in Radiation-Resistant Cervical Cancer Cells

## TL;DR

Radiation-resistant cervical cancer cells become resistant to afatinib due to EZH2 silencing PTEN, which activates AKT, and combining EZH2 inhibitors with afatinib could restore treatment effectiveness.

## Contribution

The study identifies the EZH2–PTEN–AKT axis as a novel driver of afatinib resistance in radioresistant cervical cancer cells.

## Key findings

- EZH2 epigenetically silences PTEN, leading to sustained AKT activation in radiation-resistant HeLaR cells.
- Combining EZH2 inhibitors with afatinib suppresses tumor growth in xenograft models without toxicity.
- Pharmacologic inhibition of EZH2 or PI3K/AKT restores afatinib sensitivity in resistant cells.

## Abstract

What are the main findings?
Radiation-acquired HeLaR cervical cancer cells exhibit significant afatinib resistance.EZH2 epigenetically silences PTEN, leading to sustained AKT activation.

Radiation-acquired HeLaR cervical cancer cells exhibit significant afatinib resistance.

EZH2 epigenetically silences PTEN, leading to sustained AKT activation.

What is the implication of the main findings?
Pharmacologic inhibition of EZH2 or PI3K/AKT restores afatinib sensitivity.In vivo, combination therapy with an EZH2 inhibitor and afatinib suppresses tumor growth without toxicity.The EZH2–PTEN–AKT axis represents a potential therapeutic target in recurrent and radioresistant cervical cancer.

Pharmacologic inhibition of EZH2 or PI3K/AKT restores afatinib sensitivity.

In vivo, combination therapy with an EZH2 inhibitor and afatinib suppresses tumor growth without toxicity.

The EZH2–PTEN–AKT axis represents a potential therapeutic target in recurrent and radioresistant cervical cancer.

Background: Cervical cancer remains a major global health burden, and treatment failure due to radioresistance and secondary drug resistance severely limits clinical outcomes. Enhancer of zeste homolog 2 (EZH2) is a key epigenetic regulator implicated in tumor progression. This study aimed to determine whether EZH2-mediated PTEN silencing drives afatinib resistance via AKT activation in radiation-resistant cervical cancer cells. Methods: A radioresistant cervical cancer cell line (HeLaR) was established following cumulative irradiation (70 Gy). Cell viability, clonogenic survival, methylation-specific PCR (MSP), chromatin immunoprecipitation (ChIP), and Western blot analyses were conducted. EZH2 (Dznep; tazemetostat), PI3K, and AKT inhibitors were tested in combination with afatinib. A xenograft mouse model was used for in vivo validation. Results: HeLaR cells exhibited upregulation of EZH2 and H3K27me3, downregulation of PTEN, and sustained AKT activation. EZH2 inhibition restored PTEN expression, attenuated AKT phosphorylation, and re-sensitized cells to afatinib. MSP and ChIP confirmed EZH2-mediated PTEN promoter silencing. PI3K inhibition reproduced these effects, whereas ERK inhibition had minimal impact. In xenograft models, combined treatment with Dznep and afatinib significantly suppressed tumor growth compared to single agents. Conclusions: EZH2-driven PTEN suppression promotes AKT-dependent afatinib resistance in radiation-resistant cervical cancer. Targeting the EZH2–PTEN–AKT axis may provide a potential therapeutic approach to mitigate combined radioresistance and chemoresistance in recurrent cervical cancer, although further preclinical and clinical validation is required.