SCARs: endogenous human stem cell-associated retroviruses and therapy-resistant malignant tumors

Discoveries of endogenous human stem cell-associated retroviruses (SCARs) revealed consistent activation of specific endogenous retroviral elements in human preimplantation embryos and documented the essential role of the sustained retroviral activities in the maintenance of pluripotency, functional identity and integrity of naive-state embryonic stem cells, and anti-viral resistance of the early-stage human embryos. Activation of specific SCARs, namely LTR7.HERVH and LTR5Hs.HERVK, has been demonstrated in patients diagnosed with multiple types of cancer, autoimmune diseases, neurodegenerative disorders and it is likely associated with the emergence of clinically lethal therapy resistant death-from-cancer phenotypes in a sub-set of cancer patients diagnosed with different types of malignant tumors.