[Malignant progression and resistance of cancer cells: an inducible survival program similar to the SOS system of unicellular organisms induced by environmental assaults].

The hypothesis discussed in this paper states that defence and survival strategies of cancer cells against therapeutic approaches are similar in their mechanisms and homologous in several genes to the SOS program known in bacteria and induced by several assaults. The almost ineluctable malignant progression and its acceleration in response to various therapies should then be considered as an inducible system inherited from prokaryotes and repressed in multicellular organisms through the anti-oncogene system. The later, weakened in case of some inherited mutations yields even in sporadic cases to repeated assaults and to the decrease with time of internal defences, including antioxidant mechanisms. This theory which presents in a new perspective the biological status of cancer in the frame of Darwinian evolution and hence the strategies able to control its progression, leads itself to some predictions and testable assertions: absence of any anti-oncogene homologues in unicellular organisms, built-in weaknesses in anti-oncogenes, existence of a common repressor and a common derepressor mechanism for several distinct genes involved in cancer and in response to an environmental assault, and finally a possible transfer of drug resistance genes in malignant cells as it is the case for bacteria submitted to stress conditions.