Do locally advanced and metastatic human epithelial cancers evolve in ‘placental/decidual-like microenvironments’?
Successful tumor microenvironments eventually kill the host. They are not only meant to nourish and protect tumor development, but to give them the right “soil” for perpetual malignant properties such as tissue invasion and metastasis. This can only be achieved if cancers avoid immune vigilance. A similar situation occurs in mammalian placental pregnancy but feto-maternal tolerance is required for a correct physiological process only until birth. Once a cancer microenvironment has acquired the genetic and epigenetic “placental immune editing switches” (PIES) phenotype, it seems likely that it will keep them “available”, whenever needed, for the rest of its development, because it gives cellular clones a competitive advantage to pass unnoticed by the host’s immune system. This allows primary cancers and their metastasis to continue growing in spite of new and changing antigenic landscapes.
KeywordsTumor microenvironment Placental immune editing switches (PIES) Mammalian cancers Cancer evolution Carcinogenesis
I would like to thank Ana María Moreno (Madrid) and Mary Darlow (Barcelona) for their competent help with text and references editing.
Compliance with ethical standards
Conflict of interest
The author reports no conflict of interest.
This work was carried out with no outside or institutional grants. The author is not, at present, under any relevant contractual obligations with any pharmaceutical companies.
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