The Oncolytic Activity of Myxoma Virus against Soft Tissue Sarcoma Is Mediated by the Overexpression of Ribonucleotide Reductase

Critical role for ribonucleoside-diphosphate reductase subunit M2 in ALV-J-induced activation of Wnt/β-catenin signaling via interaction with P27

Avian leukemia virus subgroup J (ALV-J) causes various diseases associated with tumor formation and decreased fertility and induced immunosuppressive disease, resulting in significant economic losses in the poultry industry globally. Virus usually exploits the host cellular machinery for their replication. Although there are increasing evidences for the cellular proteins involving viral replication, the interaction between ALV-J and host proteins leading to the pivotal steps of viral life cycle are still unclear. Here, we reported that ribonucleoside-diphosphate reductase subunit M2 (RRM2) plays a critical role during ALV-J infection by interacting with capsid protein P27 and activating Wnt/β-catenin signaling. We found that the expression of RRM2 is effectively increased during ALV-J infection, and that RRM2 facilitates ALV-J replication by interacting with viral capsid protein P27. Furthermore, ALV-J P27 activated Wnt/β-catenin signaling by promoting β-catenin entry into the nucleus, and RRM2 activated Wnt/β-catenin signaling by enhancing its phosphorylation at Ser18 during ALV-J infection. These data suggest that the upregulation of RRM2 expression by ALV-J infection favors viral replication in host cells via activating Wnt/β-catenin signaling. IMPORTANCE Our results revealed a novel mechanism by which RRM2 facilitates ALV-J growth. That is, the upregulation of RRM2 expression by ALV-J infection favors viral replication by interacting with capsid protein P27 and activating Wnt/β-catenin pathway in host cells. Furthermore, the phosphorylation of serine at position 18 of RRM2 was verified to be the important factor regulating the activation of Wnt/β-catenin signaling. This study provides insights for further studies of the molecular mechanism of ALV-J infection.

Role of Virus-Directed Therapy in Soft Tissue Sarcoma

OPINION STATEMENT

Bone and soft tissue sarcoma are rare cancers of mesenchymal origin with the characteristics of heterogeneity and diversity that account for less than 1% of solid malignant cancers. Conventional chemotherapy remains standard of care with response rates of 10-15% that are usually dependent on histologic subtype as some subtypes are chemotherapy resistant. There remains a large unmet clinical need for new and novel options promoting the development of promising therapeutic options such as immunotherapy. With more than 80 different subtypes, the heterogeneity of sarcoma requires thoughtful clinical trial design. In the sarcoma field, recent breakthroughs have occurred in the context of histology-specific approach based on underlying tumor biology. To that end, immunotherapy approaches will need to take a similar approach. Oncolytic viruses (OVs) have emerged as a promising treatment for many solid tumors and shown encouraging results in sarcoma. This review mainly focuses on collective clinical data highlighting the role of OVs as immunotherapy being used in soft tissue sarcoma (STS) and bone sarcomas. Combining OVs with T cell-activating checkpoint inhibition, adoptive cell therapy or targeted therapies may yield increased potency, improve antitumor efficacy of oncolytic virotherapy, and offer a new prospect for the treatment of sarcoma.