Motohiro Kobayashi

Establishment of a human ovarian endometrioid carcinoma cell line by constitutive expression of cyclin-dependent kinase 4, cyclin D1 and telomerase reverse transcriptase

Abstract Only a few human ovarian endometrioid carcinoma cell lines are currently available, partly due to the difficulty of establishing cell lines from low-grade cancers. Here, using a cell immortalization strategy consisting of i) inactivation of the p16INK4a-pRb pathway by constitutive expression of mutant cyclin-dependent kinase 4 (R24C) (CDK4R24C) and cyclin D1, and ii) acquisition of telomerase reverse transcriptase (TERT) activity, we established a human ovarian endometrioid carcinoma cell line from a 46-year-old Japanese woman. That line, designated JFE-21, has proliferated continuously for over 6 months with a doubling time of ~ 55 h. JFE-21 cells exhibit polygonal shapes and proliferate without contact inhibition to form a monolayer in a jigsaw puzzle-like arrangement. Ultrastructurally, JFE-21 cells exhibit well-developed rough endoplasmic reticulum, mitochondria and lysosomes in the cytoplasm, with cells contacting each other via desmosomes. G-band karyotype analysis indicated that cells had a near-tetraploid karyotype. Immunofluorescence staining revealed that the expression profile of a series of ovarian carcinoma markers in JFE-21 cells was consistent with ovarian endometrioid carcinoma. Moreover, Sanger sequencing of DNA polymerase ε (POLE) gene and immunohistochemical analysis of mismatch repair (MMR) proteins revealed that JFE-21 cells were classified as the no specific molecular profile (NSMP) subtype. In addition, JFE-21 cells were sensitive to paclitaxel and carboplatin administered to the donor as therapy. These findings indicate that constitutive expression of CDK4R24C, cyclin D1 and TERT genes may be an option to establish cell lines from low-grade cancers, including ovarian endometrioid carcinoma.

Establishment of a human ovarian clear cell carcinoma cell line mutant in PIK3CB but not PIK3CA

AbstractA human ovarian clear cell carcinoma cell line was established from a 46-year-old Japanese woman. That line, designated MTC-22, has proliferated continuously for over 6 months in conventional RPMI 1640 medium supplemented with 10% foetal bovine serum and has been passaged over 50 times. MTC-22 doubling-time is ~ 18 h, which is much shorter than most ovarian clear cell carcinoma lines reported to date. Morphologically, MTC-22 cells exhibit polygonal shapes and proliferate to form a monolayer in a jigsaw puzzle-like arrangement without contact inhibition. Ultrastructurally, cells exhibit numerous intracytoplasmic glycogen granules and well-developed mitochondria. G-band karyotype analysis indicated that cells have a complex karyotype close to tetraploid. We observed that the expression pattern of a series of ovarian carcinoma-related molecules in MTC-22 cells was identical to that seen in the patient’s tumour tissue. Notably, MTC-22 cells, and the patient’s carcinoma tissue, expressed low-sulphated keratan sulphate recognised by R-10G and 294-1B1 monoclonal antibodies, a hallmark of non-mucinous ovarian carcinoma, and particularly of clear cell ovarian carcinoma. Moreover, characteristic point mutations—one in ARID1A, which encodes the AT-rich interaction domain containing protein 1A, and the other in PIK3CB, which encodes the catalytic subunit of phosphoinositide 3-kinase—were seen in the patient’s tumour tissue and retained in MTC-22 cells. Collectively, these findings indicate that MTC-22 cells could serve as a valuable tool for investigating the pathophysiology of ovarian clear cell carcinoma, particularly that harbouring PIK3CB mutations, and for developing and validating new diagnostic and therapeutic approaches to this life-threatening malignancy.