Inflammation and Virology - Oncolytic Vaccinia Virus-HSP70-shRNA Amplifies Viral Replication, ROS/Autophagy, and Immunity to Fight Colorectal Cancer

Sep 23, 2026

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Colorectal cancer drives high mortality, yet immunotherapy underperforms in immunologically “cold” tumors. To counter this, an oncolytic vaccinia virus expressing HSP70 shRNA in the TK locus (oncoVV-shHSP70) was engineered. In CRC cells it reduces HSP70, boosts viral replication, and triggers apoptosis via Caspase-7/9 activation and Bcl-2 downregulation. The therapy accumulates ROS by inhibiting Nrf2, activates autophagy through Beclin-1/Vps34, and forms a ROS-autophagy loop that amplifies viral production, apoptosis, and cytokine release, culminating in robust antitumor immunity and tumor suppression in mouse models.

LanguageEnglish

CategoryHealthcare

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Pages14

Reading Time35 min

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Introduction

Oncolytic viruses and immunotherapy rationale

Vaccinia virus as an oncolytic platform

Background on HSP70 and stress response

Cancer Science ORIGINAL ARTICLE OPEN ACCESS Inflammation and Virology Oncolytic Vaccinia Virus-HSP70-shRNA Amplifies Viral Replication, ROS/Autophagy, and Immunity to Fight Colorectal Cancer Rentao Yuan | Ruikang Liu | Fangying Shao | Zheqi Cai | Yingfei Fang | Kan Chen | Yanrong Zhou | Ting Ye | Gongchu Li College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China Correspondence: Ting Ye ([yeting@zstu.edu.cn](yeting@zstu.edu.cn)) | Gongchu Li ([lgc@zstu.edu.cn](lgc@zstu.edu.cn)) Received: 1 September 2025 | Revised: 24 March 2026 | Accepted: 3 April 2026 Keywords: autophagy | colorectal cancer | immunotherapy | oncoVV-shHSP70 | ROS ABSTRACT Colorectal cancer persists as a major contributor to cancer mortality, with immunotherapy offering limited efficacy in immunologically “cold” tumors. To address this issue, we engineered an oncolytic vaccinia virus to express HSP70 shRNA within its TK gene locus (oncoVV-shHSP70) . In vitro, oncoVV-shHSP70 significantly suppressed HSP70 expression, enhanced viral replication, and induced apoptosis in CRC cells via Caspase-7/9 activation and Bcl-2 downregulation. OncoVV-shHSP70 also triggered reactive oxygen species (ROS) accumulation by suppressing the antioxidant regulator Nrf2 and stimulated autophagy via the Beclin-1/Vps34 pathway. Notably, a mutually reinforcing cycle between ROS overproduction and autophagy amplified the oncolytic effects of oncoVV-shHSP70, enhancing viral production, promoting apoptosis, and increasing cytokine release. Specifically, oncoVV-shHSP70 boosted cytokine production (TNF-α, IFN-α/β) through ROS/autophagy-dependent activation of AP-1 and IRF-3/7 pathways. In xenograft mouse models, oncoVV-shHSP70 induced cellular necrosis and significantly inhibited tumor growth. These findings demonstrate that oncoVV-shHSP70 enhances antitumor immunity in both syngeneic and humanized mouse models by promoting T-cell and dendritic-cell infiltration and inducing immunogenic cell death. In summary, oncoVV-shHSP70 emerges as a promising multimodal therapy for CRC, leveraging viral oncolysis, apoptosis induction, and immunomodulation to overcome therapeutic resistance. 1 | Introduction Ranking third among malignancies globally, colorectal cancer (CRC) causes 1.9 million new cases and one in ten cancer deaths annually [1, 2] . Although the incidence of CRC has decreased, 20% ofCRC patients still have synchronous metastases, and 40% of CRC patients develop metastatic disease [3] . Of note, patients with advanced CRC exhibit persistently low five-year survival rates (10%–30%). Immunotherapy shows promise in malignancy treatment but faces limited efficacy in cold CRC due to immune escape mechanisms [4] . Given the limitations of current therapies for CRC, innovative therapeutic strategies are urgently needed. Oncolytic viruses (OVs) represent a novel class of immunotherapeutics that promote anti-tumor responses via two primary mechanisms: direct lysis via oncotropic replication, and the stimulation of systemic anti-tumor immunity [5–7] . To | Abbreviations: 3-MA, 3-methyladenine; AP-1, activator protein-1; CQ, chloroquine; CRC, colorectal cancer; HSP70, heat shock protein 70; IFN-α, interferon-α; IFN-β, interferon-β; IRF3, interferon regulatory factor 3; IRF7, interferon regulatory factor 7; MOI, multiplicity of infection; OncoVV, oncolytic vaccinia virus; OVs, oncolytic viruses; PBMCs, human peripheral blood mononuclear cells; ROS, reactive oxygen species; TME, tumor microenvironment; TNF-α, tumor necrosis factor-α .
Rentao Yuan and Ruikang Liu contributed equally to this work. | | --- | | This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
© 2026 The Author(s). Cancer Science published by John Wiley & Sons Australia,

FAQs

What therapeutic strategy is used to target colorectal cancer in this study?

The study engineers an oncolytic vaccinia virus to express HSP70 shRNA at the TK gene locus (oncoVV-shHSP70).

How does oncoVV-shHSP70 suppress CRC cells?

It downregulates HSP70, enhances viral replication, and induces apoptosis via Caspase-7/9 activation and Bcl-2 downregulation.

What roles do ROS and autophagy play in the antitumor effect?

oncoVV-shHSP70 increases ROS by suppressing Nrf2 and stimulates autophagy via the Beclin-1/Vps34 pathway; a reinforcing ROS-autophagy cycle amplifies viral production, apoptosis, and cytokine release.

Sep 23, 2026

Uploaded by Bulrr