Cell‐cell fusion mediated by viruses and herv‐derived fusogens in cancer initiation and progression

Abstract

Cell fusion is a well‐known, but still scarcely understood biological phenomenon, which might play a role in cancer initiation, progression and formation of metastases. Although the merging of two (cancer) cells appears simple, the entire process is highly complex, energy‐dependent and tightly regulated. Among cell fusion‐inducing and ‐regulating factors, so‐called fusogens have been identified as a specific type of proteins that are indispensable for overcoming fusion‐associated energetic barriers and final merging of plasma membranes. About 8% of the human genome is of retroviral origin and some well‐known fusogens, such as syncytin‐1, are expressed by human (can-cer) cells. Likewise, enveloped viruses can enable and facilitate cell fusion due to evolutionarily optimized fusogens, and are also capable to induce bi‐ and multinucleation underlining their fusion capacity. Moreover, multinucleated giant cancer cells have been found in tumors derived from on-cogenic viruses. Accordingly, a potential correlation between viruses and fusogens of human endogenous retroviral origin in cancer cell fusion will be summarized in this review.