Induction of the differentiation of cultured endometrial carcinoma cells by type I collagen: Relevance of sulfolipids

Abstract

This study aimed to promote gland formation in cells derived from endometrial cancer, and assess the relevance of sulfolipids by performing culture with type I collagen. Tumors were developed in nude mice using cultured cell lines, gland formation was induced by culture with type I collagen and the composition of tumor cell sulfolipids was analyzed. Results showed that after culturing the cells on type I collagen gel, the gel was floated. Another layer of gel was placed on top so that the cells were sandwiched between two layers. Using this method, it was possible to induce gland formation in cells that formed only poorly differentiated tumors in nude mice. Mucous staining and electron microscopy demonstrated polarity of the glands. The cell lines that showed gland formation expressed sulfolipids, but not cholesterol sulfate. In conclusion, type I collagen and sulfolipids are involved in the process of gland formation in endometrioid adenocarcinoma.

Figure 1

Hematoxylin and eosin-stained specimens of the tumors formed in nude mice by the transplanted SNG-M (left panel) and HHUA cell (right panel) lines. The tumors that grew in mice injected with the cells were solid and did not show any gland formation or other signs of differentiation.

Figure 2

(a) Light microscopy of Ishikawa cells cultured by the floating type I collagen gel method. While some of the cells are slightly polarized, there are no obvious signs of differentiation, such as gland formation, in most parts of the specimen. (b) Light microscopy of SNG-M (2b-1) and HHUA (2b-2) cells cultured by the floating type I collagen gel method. SNG-M and HHUA cells exhibited a columnar shape. Glandular structures were observed. The nuclei of the cells were lined up along the basement membrane, showing obvious polarity.

Figure 3

(a) Alcian blue (acid mucopolysaccharide)-stained specimens of the SNG-M cell line cultured by the collagen gel method. Secretion of substances inside the lumens of the glands was also observed. The lumens of the glandular structure were positive for staining. (b) Transmission electron micrograph of HHUA cells cultured by the floating type I collagen gel method.

Figure 4

TLC autoradiogram of sulfolipids from 2×10⁶ cultured cells of various cell lines derived from endometrial cancer. Four sulfolipids are identified with mobilities on the TLC plate that are identical to those of cholesterol sulfate, I³SO₃-GalCer, II³SO₃-LacCer and II³SO₃-Gg₃Cer.