Thalidomide delayed the ability of 4T1 cells to amass into tumors in Balb/c mice

Thalidomide (Thal) can suppress the growth of established, as well as explanted tumors in mice. We wanted to determine if it could suppress the ability of tumor cells to assemble and establish a primary tumor at the injection site. Using the mouse 4T1 mammary tumor model, we fed Thal to mice for 4 days, then injected 10(5) 4T1 cells into the interscapular region of Balb/c mice. After 20 days on treatment with Thal, all seven control mice, fed with meal had tumors ranging from 3 to 93 mm(3) (median 20). Two of the eight mice fed with meal + Thal had no tumors, and the remaining mice had tumors ranging from 2 to 22 mm(3) (median 5). The median volume of the tumors in the control group was significantly more than that of mice treated with Thal (p = 0.03, Mann-Whitney test). In vitro treatment of the 4T1cells with Thal did not inhibit their ability to proliferate, to adhere to plastic, or to bind to Concanavalin-A. Thal caused a marked reduction in the ability of the 4T1 cells to assemble into palpable tumors.