| Summary: | One of the most important risk factors in ovarian cancer is family history, and two well-studied tumour suppressor genes BRCA1 and BRCA2 have already been identified in “high-risk” families. However, alterations of other genes may also be important for ovarian cancer pathogenesis in individuals with family history of breast/ovarian cancer.
In this thesis, I compared the gene expression profiles of tumours from patients with strong and weak family history of breast and/or ovarian cancer to identify genes that may be significant in the subset of patients with ovarian cancer predisposition. Based on this comparison, two genes of interest were selected for further investigations: hCDC4/FBXW7 (F-box and WD repeat domain containing 7) and PRKCZ (protein kinase C zeta).
Through mutational analyses I identified one nucleotide alteration within exon 7 of hCDC4; however, overall I found that hCDC4 mutation is a rare event in ovarian tumours. Additional epigenetics analyses revealed that promoter methylation is not a significant mechanism responsible for repression of hCDC4 expression in ovarian cancer. Nevertheless, the variable expression of hCDC4 proteins observed in ovarian tumour tissues by immunohistochemical staining of tissue microarrays suggests that hCDC4 deregulation may potentially be important in a subset of ovarian cancers.
Additionally, I observed that expression levels of PRKCZ are higher in ovarian tumours from patients with strong family history compared to patients with weak family history. PRKCZ has previously been shown to be involved in a variety of cellular processes; however its role in ovarian cancer remained elusive. To further understand the role of PRKCZ in ovarian tumourigenesis, including cell viability, cell migration, as well as relevant downstream signaling pathways, I performed functional assays using an in vitro ovarian cancer model. I observed that PRKCZ increases proliferation of the SKOV3 ovarian cancer cell line and participates in EGF-induced chemotaxis. Furthermore, I identified IGF1R (insulin-like growth factor 1 receptor) and ITGB3 (integrin beta 3) as downstream effectors of PRKCZ as expression of these genes is significantly altered when PRKCZ is over-expressed. Given their previously identified associations with familial ovarian cancer, the IGF1 and ITGB3 signaling pathways may therefore represent a possible link between PRKCZ and this disease.
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