Chromosomes 6 and 18 induce neoplastic suppression in epithelial ovarian cancer cells

Abstract

Metaphase comparative genomic hybridisation (CGH) studies indicate that chromosomes 4, 5, 6, 13, 14, 15, and 18 are frequently deleted in primary ovarian cancers (OC). Therefore we used microcell-mediated chromosome transfer (MMCT) to establish the functional effects of transferring normal copies of these chromosomes into two epithelial OC cell lines (TOV112D and TOV21G). The in vitro neoplastic phenotype (measured as anchorage dependent and independent growth and invasion) was compared between recipient OC cell lines and multiple MMCT hybrids. Chromosomes 6 and 18 showed strong evidence of functional, neoplastic suppression for multiple hybrids in both cell lines. We also found evidence in one cancer cell line suggesting that chromosomes 4, 13 and 14 may also cause functional suppression. Array CGH and microsatellite analyses were used to characterise the extent of genomic transfer in chromosome 6 and 18 hybrids. A 36Mb deletion on chromosome 6 in two hybrids from one cell line mapped the candidate region proximal to 6q15 and distal to 6q22.2; and an approximately 10Mb candidate region spanning the centromere on chromosome 18, was identified in two hybrids from the other cell line. These data confirm reported functional effects of chromosome 6 in OC cell lines; but to our knowledge, this is the first time that functional suppression for chromosome 18 has been reported. This suggests that these chromosomes may harbour tumour suppressor like genes. The future identification of these genes may have a significant impact on the understanding and treatment of the disease, the identification of novel therapeutic targets

MicroRNA-30c-2* Expressed in Ovarian Cancer Cells Suppresses Growth Factor–Induced Cellular Proliferation and Downregulates the Oncogene BCL9

“…The stem-loop will become 2 products: the mature major sequence, miR-30c, and the passenger sequence, miR30c-2 Ã . The intriguing connection between chromosome 6 and ovarian malignancy is that it is often deleted in primary cancers and may functionally suppress neoplasia in epithelial ovarian cancer cell lines that overexpress it (34). On the basis of the assembly of the RNA-induced silencing complex (RISC), the 2 miRNA strands are not equally eligible to populate RISC; rather, only one of the 2 strands is selected for and then loaded into RISC, which is determined by helicase initiating the duplex unwinding at the easier end (35).…”

Common alleles in candidate susceptibility genes associated with risk and development of epithelial ovarian cancer

“…MMCT of normal human Chromosome 18 was achieved by polyethylene glycol fusion of the epithelial ovarian cancer cell lines TOV112D and TOV21G (American Tissue Culture Collection, LGC Standards, Middlesex, United Kingdom)18 and mouse (A9): human monochromosome hybrid donor cell lines carrying a selectable fusion gene marker, hygromycin phosphotransferase 1717.…”

“…In vitro phenotypic analysis was performed by assaying anchorage independent growth in soft agar and invasion through matrigel as described previously 17. For MMCT hybrids displaying significant neoplastic suppression, a combination of cytogenetic analysis, DNA microarray analysis and microsatellite genotyping confirmed the uptake of a complete or partial human chromosome 18 in MMCT hybrids.…”

“…In our study, we have evaluated the effects on ovarian cancer risk of common variants in nine candidate susceptibility genes ( AIFM2, AKTIP, AXIN2, CASP5, FILIP1L, RBBP8, RGC32, RUVBL1 and STAG3 ) identified after performing microcell-mediated chromosome transfer (MMCT) of chromosome 18 into ovarian cancer cell lines16,17 as described below. These genes were first genotyped in 1,799 invasive ovarian cancer cases and 3,045 unaffected controls from three studies; significant associations were genotyped in an additional 4,590 cases and 6,031 controls from ten studies that are part of the OCAC, resulting in a total of 6,389 invasive ovarian cancer cases and 9,076 controls from 13 studies.…”

A Xenograft Mouse Model Coupled with In-depth Plasma Proteome Analysis Facilitates Identification of Novel Serum Biomarkers for Human Ovarian Cancer

“…The TOV-112D cells were maintained in a 37° C incubator with a 5% CO 2 −95% air atmosphere in a 1:1 mixture of MCDB 105 media and Medium 199 (Sigma-Aldrich, St. Louis, MO) supplemented with 15% fetal calf serum, as described previously. 40 …”