A study suggests that the maternal-foetal "anti-rejection" mechanisms could prove crucial for the development of cancer
Humans accumulate potentially carcinogenic mutations throughout life, though not everyone develops cancer - probably because our immune system is able to control and arrest its growth. A team led by Dr. Miquel H. Bronchud, of the Dr. Bellmunt Oncological Institute, and composed of oncologists, gynaecologists-obstetricians and pathologists of the Dexeus University Hospital and Women’s Health Dexeus Centre, including Dr. Francesc Tresserra and Dr. Bernat Serra, has carried out a study that opens a new line of research for determining how tumour cells are able to evade the natural immune vigilance mechanisms by activating intrinsic immune regulating programs such as those that physiologically allow maternal-foetal tolerance.
With this objective in mind, and thanks to the availability of different biological tissues from a patient that developed breast cancer at the end of pregnancy (placenta, breast tumour tissue, breast normal tissue, normal lymph node, metastatic lymph node and decidua [endometrial tissue attached to the placenta]), a study was started to establish which immune regulating genes allowing maternal-foetal tolerance were present in the placenta of the patient. The authors identified several dozens of genes that were found not only in the placenta but were also over-expressed or silenced in the tumour tissues, and which in their opinion could represent a strategy used by the cancer cells to evade the natural immune vigilance mechanisms.
According to the investigators, these data in principle can also be extrapolated to many other cancer. These genes are not unique to women or to breast cancer or pregnancy, since in theory all mammalian cells possess genetic immune control programs associated to the maternal-foetal tolerance potential of the placenta, and both men and women share chromosomes - including sex chromosome X. The authors thus believe that their study hypothesis might help to partially explain why the most aggressive cancers in terms of local invasion and metastasis are usually found in mammals, and not in other vertebrates or invertebrates, or plants. However, they recognise that many more studies involving many more patients will be needed in order to screen the genomic findings to identify those genes which really prove crucial for these immune-evading mechanisms, with a view to intercepting and blocking their expression.
The results of this study, published in the journal Oncotarget, can be consulted online.
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Bronchud MH, Tresserra F, Xu W, Warren S, Cusido M, Zantop B, Zenclussen AC, Cesano A.
Oncotarget. 2016 Nov 11. doi: 10.18632/oncotarget.13306.