When asked “is cancer a virus explain”, people usually say “no.” This is because the virus’s DNA combines with the host’s, creating a hybrid cell with abnormal genetic code. When these cells begin to replicate out of control, the result can be cancer. While many viruses do not reach Step 4, there are a few that have been linked to cancer. Here’s what they do. In a cancer cell, viruses attach to the DNA and change its behavior.
A cancer cell ignores signals from other cells to stop dividing and die, causing it to spread to other parts of the body. When it does, it invades nearby tissue and spreads to distant regions. By contrast, normal cells cease to grow when they encounter other cells, and move around in the body only when they need to. Those blood vessels are also used to supply tumors with oxygen and nutrients and remove waste products. In addition to the tumor’s ability to spread, cancer cells also trick the immune system into helping them grow. They convince some immune cells to protect the tumor.
Although bacteria and viruses have been linked to cancer since the early 1960s, it was only in recent decades that viruses and bacteria were finally accepted as contributing causes of the disease. In the 1960s, some fringe scientists began to claim that they had discovered a “germ” that causes cancer. The medical establishment ignored these theories, and in 1965, the American Cancer Society included Coley’s toxins on its list of “unproven methods for cancer treatment.”
The seven oncoviruses that cause cancer share a number of features in common. They perturb numerous cellular pathways and provide the body with foreign genomes and gene products. These foreign proteins overcome the barriers to cellular carcinogenesis. The presence of oncoviruses has important implications in epidemiology and cell cycle control. But they do not cause cancer in all individuals. The majority of viruses do not cause cancer. This is because they co-evolve with their host.
Human tumor viruses are responsible for about 12% to 20% of all cancers worldwide. Infections with these viruses can be prevented by vaccines, which protect against the infection. In the meantime, the immune system can become weakened, enabling the viruses to hijack proliferating human cells. This makes these viruses particularly important because they can establish persistent infections. While human tumor viruses are the most common cause of cancer, many people do not receive the necessary vaccines to prevent cancer.
While many types of cancer cells are characterized by heterogeneity, viruses can promote this heterogeneous phenotype in the host cell. Because they are unstable, these viruses can shift between productive and nonproductive gene programs. Some viral genomes also exhibit increased flexibility as they transition from latent to lytic infection cycles. This flexibility may enhance the variability of gene expression in the host cell, allowing oncoviruses to cause cancer.
