Correlation between the presence of microvilli and the growth or metastatic potential of tumor cells.

We used an electron microscope to examine microvilli which appear on the surfaces of various tumor cells with high or low growth potential and/or metastatic ability. The results show that a greater number of microvilli appeared on the surfaces of tumor cells (QRpP and ERpP) which possess high growth potential than on tumor cells (QR and ER) with low growth potential. We also observed that microvilli were more abundant on the surface of highly metastatic clone cells, i.e. c-SST-2 (cl-2), mouse B16 melanoma (F-10) and human colon carcinoma (KM12SM) than on weakly metastatic clone cells, c-SST-2 (cl-4-2), B16 (F-1) and (KM12C). At the same time, more microvilli were observed on the surface of B16 BL6 cells, which were obtained from the metastatic site of the B16 F10 cells, than on the surface of the parent B16 F10 cells. Immunoelectron microscopy revealed that the c-neu oncogene product, which is closely related to an epidermal growth factor receptor, was positively stained in the microvilli of tumor cells (ERpP) with high growth potential and high metastatic ability, whereas the tumor cells (ER) with low growth potential and weak metastatic ability were not stained. These findings suggest that the increased presence of microvilli correlates closely with the growth potential and metastatic ability of tumor cells.

weakly tumorigenic cells obtained from BMT‐11 cells treated with quercetin

weakly tumorigenic cells obtained from c‐SST‐2 cells treated with EMS

a highly tumorigenic clone derived from QR by implantation of QR cells attached to plastic plates

a highly tumorigenic clone derived from ER by implantation of ER cells attached to plastic plates

spontaneously hypertensive rats

spontaneously developed rat mammary adenocarcinoma

ethyl methanesulfonate

KMT‐17 cells infected with Friend leukemia virus

scanning electron microscope