CAISMOV24, a new human low-grade serous ovarian carcinoma cell line

Abstract

Background: The spontaneous immortalization of primary malignant cells is frequently assigned to their genetic instability during in vitro culturing. In this study, the new epithelial ovarian cancer cell line CAISMOV24 was described and compared with its original low-grade serous ovarian carcinoma.

Methods: The in vitro culture was established with cells isolated from ascites of a 60-year-old female patient with recurrent ovarian cancer. The CAISMOV24 line was assessed for cell growth, production of soluble biomarkers, expression of surface molecules and screened for typical mutations found in serous ovarian carcinoma. Additionally, comparative genomic hybridization was employed to compare genomic alterations between the CAISMOV24 cell line and its primary malignant cells.

Results: CAISMOV24 has been in continuous culture for more than 30 months and more than 100 in vitro passages. The cell surface molecules EpCAM, PVR and CD73 are overexpressed on CAISMOV24 cells compared to the primary malignant cells. CAISMOV24 continues to produce CA125 and HE4 in vitro. Although the cell line had developed alongside the accumulation of genomic alterations (28 CNV in primary cells and 37 CNV in CAISMOV24), most of them were related to CNVs already present in primary malignant cells. CAISMOV24 cell line harbored KRAS mutation with wild type TP53, therefore it is characterized as low-grade serous carcinoma.

Conclusion: Our results corroborate with the idea that genomic alterations, depicted by CNVs, can be used for subtyping epithelial ovarian carcinomas. Additionally, CAISMOV24 cell line was characterized as a low-grade serous ovarian carcinoma, which still resembles its primary malignant cells.

Keywords: Ascites; Cell culture; Comparative genomic hybridization; KRAS.

Fig. 1

Peritoneal implant of low-grade serous ovarian carcinoma. a obj 10× and b obj 40×

Fig. 2

a Different time points of the in vitro growth of the CAISMOV24 cell line. CAISMOV24 cells were launched at 10⁴ cells/cm² in HAM F10 medium supplemented with 2 mM L-glutamine and 10% fetal bovine serum. b Representative growth curve for the CAISMOV24 cell line, assessed from the 63rd to the 100th in vitro passages. c Proliferation profile of CAISMOV24 cells assessed by flow cytometry on day 5, following cell labeling with violet proliferation dye 450 (VPD450); the shaded areas represent each of the new cell generations, which retained approximately half of the VPD450 fluorescence intensity of its parent cell. Mean proliferation index of CAISMOV24 cells resulted in 3.94 ± 0.94 times

Fig. 3

Flow cytometric profiles representative of the fluorescence intensity of the molecules, HLA-class I, PVR (CD155), EpCAM (CD326), TGF-β1, CD39 and CD73, comparing the expression of these surface molecules between the CAISMOV24 cell line and its primary malignant cells. The cells were incubated with appropriate concentrations of fluorochrome-conjugated monoclonal antibodies. After incubation, cells were washed with PBS and the final cell pellets suspended for acquisition, using a FACS Verse flow cytometer. The K562 cell line was employed as a negative control for most of the surface molecules assessed in this assay

Fig. 4

Representative G-banded karyotype of a CAISMOV24 cell with 54 chromosomes. Dic = dicentric chromosome, add = additional material of unknown origin

Fig. 5

Image captured from software ChAS (Affymetrix, USA) summarizing chromosomal aberrations found across the genome of the CAISMOV24 cell line compared with its primary malignant cells. Extensive alterations, involving long genomic sequences, were detected in chromosomes 3, 5, 7, 8, 12, 13, 14, 19 and X, both in the CAISMOV24 cell line and its primary malignant cell. X axis = Chromosomes; Left y axis = Allele differences (gray); Right y axis = Copy number state (black)