A national screening programme could significantly reduce mortality from epithelial ovarian
cancer (EOC). The biological events that occur in the early stages of development
of EOCs remain poorly understood, thus hindering the discovery of biomarkers of early
disease. This thesis describes the development of a three-dimensional heterotypic genetic
model of neoplastic transformation of normal ovarian surface epithelial (NOSE) cells.
hTERT, C-MYC, KRAS and BRAF are genes that are commonly mutated or overexpressed
in EOCs. Ectopic expression of hTERT increased in vitro lifespan of NOSE
cells without inducing neoplastic transformation. Subsequent overexpression of CMYC
+/- KRASG12V /BRAFV 600E in immortalised NOSE (IOSE) cells induced a significant increase
in anchorage-independent growth and invasive ability. In in vitro assays and gene
expression microarrays, phenotypic and molecular heterogeneity was associated with differential
oncogene expression. Physiological and biological features of NOSE cells grown
in 3D more closely resembled characteristics of NOSE cells in vivo than when grown by
classical two-dimensional (2D) approaches. 3D models of oncogene-expressing clones revealed
characteristics of malignant cells in vivo that could not be detected in 2D monolayer
cultures.
Gene expression microarrrays profiles of ~25,000 genes were generated to identify novel
genes that are altered synergistically with the oncogenes that were introduced. A panel of
genes has been identified that provides novel candidates for detecting ovarian carcinomas
at the earliest, most treatable, stages of disease.
Finally, a role for ageing fibroblasts in the initiation of EOC development was explored.
In 2D and 3D in vitro co-culture assays, pre-senescent and senescent ovarian fibroblasts
differentially affected proliferation, anchorage-independent growth, migration and invasion
of IOSECMYC cell lines but not of IOSE cells. These data provide in vitro evidence that
the ageing microenvironment can promote transformation of ovarian epithelial cells, and
that this is conditional upon mutation in the OSE