Evidence against apoptosis as a major mechanism for reproductive cell death following treatment of cell lines with anti-cancer drugs

An increase in apoptotic cells may be observed after treatment with chemotherapy, and many authors have assumed that anti-cancer drugs kill cells by inducing apoptosis. The most relevant endpoint of cell death following treatment of tumour cells is loss of reproductive ability as measured by a colony-forming assay, since cells with limited reproductive potential cannot regenerate a tumour. We have therefore investigated the relationship between apoptosis and reproductive cell death following in vitro treatment of mammalian cell lines with anti-cancer drugs. Markers of apoptosis (DNA ladders, TUNEL assay) were evaluated at various times after treatment of Chinese Hamster Ovary (CHO) cells, human bladder cancer MGH-U1 cells, and a murine T-lymphocytic cell line (CTLL-2) with several anti-cancer drugs. These markers were found infrequently, despite the use of doses that cause loss of colony-forming ability, except in CTLL-2 cells. We also transfected and expressed the human pro-apoptotic gene bax and the anti-apoptotic gene bcl-2 in MGH-U1 cells and compared cell survival after drug treatment with that of control cells transfected with the vector alone. Expression of these genes had at most small effects to influence cell survival. We conclude that apoptotic mechanisms had at most a minor role in leading to reproductive death of MGH-U1 and CHO cells after chemotherapy. When apoptosis is observed following treatment with anti-cancer drugs it may be a secondary event which occurs in lethally-damaged cells, leading to their lysis, rather than a primary event that leads to loss of reproductive integrity. © 2001 Cancer Research Campaign http://www.bjcancer.co

Interplay between distribution of live cells and growth dynamics of solid tumours

Experiments show that simple diffusion of nutrients and waste molecules is not sufficient to explain the typical multilayered structure of solid tumours, where an outer rim of proliferating cells surrounds a layer of quiescent but viable cells and a central necrotic region. These experiments challenge models of tumour growth based exclusively on diffusion. Here we propose a model of tumour growth that incorporates the volume dynamics and the distribution of cells within the viable cell rim. The model is suggested by in silico experiments and is validated using in vitro data. The results correlate with in vivo data as well, and the model can be used to support experimental and clinical oncology