Which of the following statements best supports the hypothesis that viruses can cause cancer?
A.
Cellular DNA has sequences related to viral sequences.
B.
Cancerous and normal cells share genetic sequences.
C.
Viruses and cancer cells both replicate rapidly.
D.
Genes that regulate cell division are found in some viruses.
The correct answer and Explanation is :
The statement that best supports the hypothesis that viruses can cause cancer is D. Genes that regulate cell division are found in some viruses.
Explanation:
Viruses can play a significant role in cancer development through the integration of their genetic material into the host cell’s DNA. Some viruses, known as oncogenic viruses, contain genes that can alter normal cellular functions, particularly those regulating cell division and apoptosis (programmed cell death). These genes can interfere with the normal regulatory pathways that control the cell cycle, leading to uncontrolled cell proliferation.
For instance, human papillomavirus (HPV), a well-known oncogenic virus, produces proteins such as E6 and E7 that can inactivate tumor suppressor proteins like p53 and Rb. By disrupting these critical regulatory proteins, HPV can push cells towards malignant transformation. Similarly, the Epstein-Barr virus (EBV) and hepatitis B virus (HBV) have been associated with various cancers through their ability to manipulate the host’s cellular machinery, leading to uncontrolled growth.
While statement A points out that cellular DNA has sequences related to viral sequences, this does not directly indicate a causative relationship with cancer; it merely suggests a possible interaction. Statement B, which mentions that cancerous and normal cells share genetic sequences, does not provide a clear link to viral involvement. Statement C, stating that viruses and cancer cells both replicate rapidly, is also not a strong indication of causation since rapid replication can occur in many biological contexts unrelated to cancer.
Thus, the presence of specific viral genes that can modify the host’s cellular mechanisms, particularly those involved in cell division, directly supports the hypothesis that viruses can lead to cancer development. Understanding these mechanisms is crucial in cancer prevention and treatment strategies, highlighting the importance of vaccines and antiviral therapies in reducing cancer risk associated with viral infections.