Why Do Viruses Really Kill Cancer Cells?

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Cancer is one of the leading causes of mortality worldwide. While chemotherapy and radiotherapy are effective against certain types of cancer, they are accompanied by adverse side effects and are known to indiscriminately attack cells --not just cancer cells. Cytostatic drugs typically do not exclusively attack cancer cells, they attack rapidly dividing healthy cells, also.1 Due to the harsh side effects of chemotherapeutic drugs, other options with more resolution to target solely cancer cells are being explored, specifically, viral chemolytics. Viruses are capable of killing cancer cells by several methods, such as “direct lysis, apoptosis, expression of toxic proteins, autophagy and shut-down of protein synthesis, or the induction of anti-tumoral immunity.”2 The ability of viruses to attack cancer …show more content…
Tumor cells are made up of continually dividing cells because of altered telomere activity, causing the rapid and constant proliferation of these cells. Because virions require host cell machinery to replicate, these amplified levels of DNA and protein synthesis in dividing cancer cells make tumor cells better hosts for viral reproduction than non-dividing normal cells.8 Oncolytic viruses are able to hijack the replication machinery of cancer cells as a result of the defective antiviral defenses within tumor cells.5 According to Russell, “Normal cells respond to virus infection by downmodulating their metabolism and/or by undergoing apoptosis, thereby inhibiting virus propagation.”5 Consequently, oncolytic viruses must also combat the body’s innate immune system, as they are vulnerable to antiviral host defenses, such as interferons, killer cells, cytotoxic T cells, and antiviral antibodies.3 Battling the innate immune system is one of the key issues with efficacy of oncolytic