Effect of autologous serum and steroid hormone receptors on direct cloning of human breast cancer.

Thirty-seven samples of human primary breast cancer were processed for direct cloning in methylcellulose (MC) cultures. Of the 37 specimens plated, 19 tumors (51%) grew with a plating efficiency (PE) of 0.012%. Both growing and nongrowing tumors belonged mostly to the ductal histologic type. The use of autologous serum v fetal calf serum did not affect the PE. Moreover, a negative correlation was found between the level of estrogen receptors and especially of progesterone receptors (PRs) and the ability of tumors to grow in MC culture. These findings underline the difficulty of cloning fresh specimens of human solid tumors and indicate that malignant cells with a high concentration of PRs may also have a degree of differentiation that leads to a reduced clonogenic ability.