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The mysterious journey of the mouse mammary tumor virus: How is cancer transmitted from breast milk?
In experiments on mice, mammary tumor virus (MMTV) has attracted the attention of scientists since it was first discovered in 1936. This transmission occurs through breast milk, making it possible for the offspring of mice to become infected with the virus and develop breast cancer. Researchers are beginning to delve deeper into how the virus infects people and its possible impact on cancer.
MMTV is one of the major causes of mammary tumors and is passed to mouse pups through its presence in breast milk.
MMTV is a retrovirus that belongs to the genus Betaretrovirus. The virus can infect offspring endogenously (i.e., inherited from the mother) or exogenously (i.e., transmitted through breast milk) in mice. Once the virus enters the host, the mice's immune systems are affected, potentially leading to the development of cancer.
Virus life cycle
When mouse pups ingest MMTV through breast milk, the virus is first absorbed by intestinal cells, then spreads to Peyer's patches and infects macrophages and lymphocytes. As the virus replicates, the trachoma virus genome eventually integrates into the host's DNA. This process involves reverse transcriptase, which reverse-transcribes the virus's RNA genome into DNA, forming an intermediate called a provirus. If the virus's genome inserts and activates certain tumor genes, cell proliferation may be out of control, eventually leading to tumor formation.
In addition, MMTV also encodes superantigens, which further promotes the proliferation of T cells and contributes to the expansion of metastasis and infection processes.
It is worth noting that Hormonal responsiveness is crucial for the carcinogenicity of MMTV. During puberty, hormones such as estrogen stimulate the expression of viral genes and cause all breast cells to contain active retroviruses. As tumors form, proliferation of these cells may become inevitable.
Model research on human breast cancer
Using the long terminal repeat (LTR) of MMTV as a promoter, scientists were able to create a model system more consistent with human breast cancer. These model systems can help study the progression of human breast cancer and can be used to validate potential treatment strategies.
Among various mouse models, the PyMT model is widely used because it can provide biological characteristics that are closer to human breast cancer.
The MMTV-PyMT model demonstrates reliable construction of breast cancer metastasis and has a positive impact on future cancer treatment. Although the T antigen in the polyvirus has not been found in human breast cancer, its application in mice has shown certain promise.
Future research directions
Many questions remain to be answered. For example, how to accurately block the spread of the virus and avoid unnecessary cancer development? If an effective method can be found to inhibit the presence of such viruses in breast milk, it may provide new help for the health of mice and other mammals.
MMTV research is not only relevant to mice, but may also provide new ideas for the treatment of human cancer.
With the advancement of science and technology, in-depth research on MMTV will inevitably reveal more details and further help understand the close relationship between viruses and tumors. This is not just for the health of the mice, but for the well-being of the entire ecosystem. How to effectively use these research results may become an important topic in future cancer research?
