Ehrlich-Lettre Ascites, Strain E

Tumor Induction Patterns in Mice Inoculated with Irradiated EAC Cells

Balakin et al. investigated the pattern of tumor induction in mice inoculated with Ehrlich ascites carcinoma (EAC) cells irradiated ex vivo with high doses of carbon ions (C) or X-rays.

As shown in Figure 1, mice inoculated with non-irradiated cells formed tumors by day 5. On the other hand, tumors appeared later in groups receiving irradiated cells in a dose-dependent fashion. The first tumors appeared on day 7 (5 Gy), day 11 (10 Gy) and day 21 (20 Gy) for C irradiation. Tumors were observed on day 11 (20 Gy), day 14 (30 Gy) and day 18 (40 Gy) after X-ray irradiation

At day 30 the tumor incidence in the C groups was 88% (5 Gy), 89% (10 Gy) and 35% (20 Gy), and no tumors were observed at 30 Gy (Fig. 1a). The incidences were 88%, 70%, 80% and 0% at 20, 30, 40 and 60 Gy, respectively, by X-ray irradiation (Fig. 1b). Tumor latency was significantly increased with dose, but the percentage of tumors induced within one month was not significantly different at lower doses for either type of radiation. This is consistent with previous studies on the proton irradiated cells, which indicate that the tumor cell death at early time points may promote the proliferation and differentiation of cancer stem cells (CSCs) in a radiation type-dependent manner.