癌生长是寄主中的过寄生现象

报道了人乳腺癌细胞MCF7和正常细胞MCF10，MRC5混合培养实验，分析了实验结果．结果表明：在营养物充足条件下癌细胞和正常细胞系寄生共存关系，而在饥饿条件下癌细胞和正常细胞是过寄生-捕食者和食饵的关系．讨论了此结果的生物医学含义．

Cancer Growth is Superparasitism in Host: a Predator-Prey Relationship

Cancer and surrounding normal tissue live together in a parasite-host relationship.It is an unidirectional competition where cancer cells numerically inferior to host,thrieve on host cells numerically superior.In ecosystem of man a small group of transformed cells in particular tissue/organ change the stability constraints of mass and energy flow at thermodynamically non-equilibrium state.Conditions which favor the cancer cell or limit the growth or survival of its normal counterpart were defined.In particular,the normal cell can feed the cancer cell under lack of nutrients in the absence of serum in the media.In the experiment the normal human breast (MCF10) cells and normal human fibroblasts (MRC5) cells were incubated in the presence of human breast cancer MCF7 cells as mixed cultures.Normal cells were able to feed the tumor cells.In the mixed cultures the growth rate of normal and tumor cells never reach the sum of the two individual cell growth.The feeder properties of various cell lines were studied when large number of preexisting cells were used as feeders for cancer cells in serum free nutrient media.The serum as a growth factor was replaced with living cells.The role of fibroblasts as candidates to be feeders was shown.The experimental results can be summarized by defining a competition factor F.In general F is divided into three regions:F＞0,exclusion region;F≥0 but near 0,parasitism region;and F＜0,super-parasitism region.The larger the competition factor,the stronger the exclusion effect between two kinds of cells.It is found that the competition exclusion between two normal cells is stronger than one normal and one cancer in vitro in the presence of serum under enough nutrients.That means F in parasitism region and the cancer cell in parasitic coexistence with the normal cell.However,the case is quite different during starvition from lacking of nutrients.All results of co-cultivation of cancer and normal cells without serum having F＜0 (super-parasitism region) are found.It means a predator-prey-like relationship occurring in the system.