No description available.

No description available.

No description available.

No description available.

No description available.

Fes was first discovered as a protein-tyrosine kinase-encoded by the v-fes retroviral oncogene. Retrovirally encoded Fes oncoproteins induced tumors in chickens and cats and cause tumors in transgenic mice; however, a role for Fes in human cancer has not been established. This thesis identifies tumor promoting roles of Fes through effects on stromal cells using genetic mouse models. First, in an orthotopic mouse mammary gland engraftment model, I found that loss of Fes in the host correlated with reductions in engrafted tumor growth rates, metastasis and circulating tumor cells, which may be partly due to reduced vascularity and fewer tumor-associated macrophages. We also showed Fes-deficient macrophages were less capable of promoting tumor cell invasion in co-culture experiments. Next, I observed delayed tumor onset in the absence of Fes in a transgenic mouse model of breast cancer driven by an activated HER2/Neu allele. This longer tumor latency correlated with hyperinflammatory status of Fes-deficient normal mammary glands. Taken together, these observations argue that Fes inhibition might provide therapeutic benefits in breast cancer, by attenuating tumor-associated angiogenesis and the metastasis-promoting functions of tumor-associated macrophages, or by delaying breast tumor onset in women with HER2 overexpression. Finally, we showed that mice engrafted with IL-4 producing tumor cells developed tumors with significantly reduced growth rates and a complete attenuation of lung metastasis, which correlated with increased numbers of macrophages and enhanced phagocytic capability of macrophages in the tumor microenvironment. These observations suggest that IL-4 could be a good candidate for immunotherapy. / Thesis (Ph.D, Pathology & Molecular Medicine) -- Queen's University, 2013-12-18 11:44:40.294

Flaxseed oil (FO), rich in α-linolenic acid, has been shown to inhibit breast cancer growth. One suggested mechanism is through modulation of HER2 expression and signalling. This study determined the effect of FO on the growth of established HER2-overexpressing breast tumours (BT-474) and its interaction with two doses of a primary anti-HER2 therapy, trastuzumab (TRAS), in athymic mice. FO alone had no effect on tumour size, cell proliferation and apoptosis. TRAS (2.5 and 5 mg/kg) reduced tumour size and cell proliferation but had no effect on apoptosis. TRAS (2.5 mg/kg) combined with FO reduced tumour size and cell proliferation and increased apoptosis compared to TRAS (2.5 mg/kg) alone and was just as effective as 5 mg/kg TRAS. TRAS (5 mg/kg) resulted in almost complete tumour regression with or without FO. In conclusion, FO has no effect on BT-474 tumour growth but can enhance the effectiveness of low dose TRAS.

The human Fyn-related kinase (FRK) is a member of subfamily of Src-related kinases family. FRK is 54 kDa non-receptor tyrosine kinase protein composed of 505 amino acids. FRK consists of three functional domains: Src homology 3 (SH3), SH2 and kinase domain, as well as a putative tyrosine kinase regulator at the C-terminus. FRK has a conserved auto-regulatory tyrosine residue within its kinase domain. It has been reported that FRK is repressed in about 30 % of human breast cancer samples. Over-expression of FRK in breast cancer cells of the mammary gland was shown to suppress cell growth by interacting, phosphorylating and stabilizing the tumor suppressor PTEN, thus inhibiting AKT/PI3K signaling. Although it has been suggested that FRK is a tumor suppressor gene, the effects of activated FRK on cell proliferation, migration and invasion are unclear. Likewise, the signaling pathways regulated by the activation of FRK have not been yet fully characterized. We hypothesize that the activation of FRK is essential for the regulation of its cellular functions. Mutation of the C-terminal auto-regulatory tyrosine 497 to phenylalanine (FRK-Y497F) resulted in the constitutive activation of FRK. We generated stable cell lines expressing either the FRK wild type (FRK-WT) or FRK-Y497F from triple negative breast cancer MDA-MB-231 cells. The introduction of FRK-Y497F in MDA-MB-231 cells significantly suppressed their proliferation, migration, invasiveness and colony formation as compared to cells that expressed the FRK-WT gene. Over-expression of either FRK-WT or FRK-Y497F in MDA-MB-231 cells inhibited the phosphorylation of AKT, STAT3, JNK and P38 MAPK as compared to either the MDA-MB-231 parental cells or those that were transfected with the empty vector. Our results suggested that FRK represses cell proliferation, migration, invasiveness and colony formation at least in part by the inhibiting the activation of AKT/PI3K, JAK-STAT and MAPK signaling pathways.

Fifteen years ago, the Steroid receptor RNA activator (SRA) was identified as a functional non-coding RNA able to increase the activity of the estrogen receptor (ER), a critical player mediating the mitogenic role of estradiol in breast cancer. Interestingly, four years later, SRA appeared to be the first ever discovered functional RNA also able to encode a protein (SRAP). As such, the products of the SRA1 gene delineate a fascinating bi-faceted system involving both a functional RNA and a protein. Since its discovery, the non-coding aspect of this system has been widely investigated, with multiple groups gathering information on SRA structure and related functions. Overall, the non-coding SRA transcript is thought to act as a broad co-regulator modulating the activity of different transcription factors. Conversely, limited information has been obtained on the coding aspect (SRAP) of this system，even though SRA/SRAP is currently believed as a whole to be involved in several mechanisms including tumourigenesis, tumour progression, myogenesis and adipogenesis. In this body of work, I have attempted to define the clinical relevance of SRAP to breast cancer and extend the understanding of the cellular processes potentially regulated by this protein. I have first established that SRAP had the potential to become a new prognostic and predictive factor in specific groups of patients. Indeed, I have demonstrated, using tissue microarray analyses (TMAs), that SRAP expression was up-regulated in some breast tumours, with high levels associated with poor prognosis in Estrogen Receptor (ER) positive breast cancer patients. Using the same technique, I have further identified a positive association between a positive response to tamoxifen treatment and a high level of SRAP expression in a large cohort of ER-α negative cases. This highlights the potential for SRAP to become a new predictive factor of response to endocrine therapy in this specific group of patients. Using RNA-seq to define the transcriptomes of cervical Hela and breast MDA-MB-231 cancer cells upon depletion or overexpression of this protein, I further identified cellular movement amongst the potential cellular processes affected by changes in SRAP expression. Using classical trans-wells assays as well as an live-cell imaging assays, I have confirmed that SRAP indeed regulates individual cancer cell motility. Overall, my results provide critical new insights into the potential functions of the protein counterpart of the intriguing SRA/SRAP bi-faceted gene system. SRAP herein appears as a potential new therapeutic target in the fight against breast cancer that remains to be further investigated. / February 2017

University of Macau / Faculty of Health Sciences