An immunohistopathological and functional investigation of β3 integrin antagonism as a therapeutic strategy in cancer. Characterisation, development, and utilisation of preclinical cancer models to investigate novel ¿3 integrin anatgonists.
AuthorAlshammari, Fatemah O.F.O.
SupervisorShnyder, Steven D.
Sheldrake, Helen M.
Patterson, Laurence H.
KeywordIntegrins; Integrin antagonists; Tumour cell migration; Histopathology of integrin experssion; αIIbβ3; αVβ3; Cancer therapy
The University of Bradford theses are licenced under a Creative Commons Licence.
InstitutionUniversity of Bradford
DepartmentInstitute of Cancer Therapeutics
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AbstractTumour cell dissemination is a major issue with the treatment of cancer, thus new therapeutic strategies which can control this process are needed. Antagonism of integrins highly expressed in tumours is one potential strategy. The integrins are transmembrane glycoprotein adhesive receptors. Two of the integrins, αVβ3 and αIIbβ3, are highly expressed in a number of tumours and induce bi-directional signalling through their interaction with extracellular matrix proteins, and growth factor receptors. Through this signalling they play an important role in a number of cellular processes that are involved in tumour dissemination such as tumour growth, migration, invasion, metastasis and angiogenesis. Dual αIIbβ3 and αVβ3 integrin antagonism will have a direct effect on β3-expressing tumour cells that leads to the inhibition of cell migration and dissemination. Furthermore, through targeting tumour cell interaction with endothelial cells and platelets, this will also lead to inhibition of angiogenesis and metastasis. The aim of this project was to characterise the expression of αVβ3 and αIIbβ3 integrin in a panel of tumour cell lines and in human tumour xenograft samples, and to develop and utilise cell-based models to investigate potential novel β3 antagonists. The expression of αV and β3 subunits was detected in xenograft tissue using immunoblotting techniques. A panel of cell lines of different tumour types including melanoma, prostate, breast, colon and non small cell lung carcinoma was then characterised for αVβ3 and αIIbβ3 integrin expression using immunoblotting and immunocytochemistry. Melanoma cell lines demonstrated the strongest αVβ3 expression. No αIIbβ3 integrin expression was seen in any of the cell lines evaluated. A selection of cell lines with varying αVβ3 expression were then used to develop a functional test for cell migration, the scratch wound healing assay. Migration of tumour cells that expressed αVβ3 integrin was inhibited by the known β3 antagonists, cRGDfV peptide and LM609 antibody. A panel of 12 potential novel β3 integrin antagonists was screened for cytotoxicity and activity in the validated scratch assay. ICT9055 was the most effective antagonist in inhibition of M14 cell migration as determined by the scratch assay, with an IC50 of < 0.1 µM. Therefore the work presented in this thesis has established models and tools for evaluating potential novel β3 integrin antagonists, and identified a promising molecule to progress for further preclinical evaluation.
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Strategies to inhibit tumour associated integrin receptors: rationale for dual and multi-antagonistsSheldrake, Helen M.; Patterson, Laurence H. (2014)The integrins are a family of 24 heterodimeric transmembrane cell surface receptors. Involvement in cell attachment to the extracellular matrix, motility, and proliferation identifies integrins as therapeutic targets in cancer and associated conditions; thrombosis, angiogenesis and osteoporosis. The most reported strategy for drug development is synthesis of an agent that is highly selective for a single integrin receptor. However, the ability of cancer cells to change their integrin repertoire in response to drug treatment renders this approach vulnerable to the development of resistance and paradoxical promotion of tumor growth. Here, we review progress towards development of antagonists targeting two or more members of the RGD-binding integrins, notably αvβ3, αvβ5, αvβ6, αvβ8, α5β1, and αIIbβ3, as anticancer therapeutics.
The effects of TGF-β on the behaviour of a keratinocyte cell line: implications in wound repairDenyer, Morgan C.T.; Youseffi, Mansour; Berends, Rebecca F. (University of BradfordSchool of Life Sciences, 2012-02-29)TGF-β isoforms are important signalling molecules in wound repair in the skin. Transforming growth factor β3 (TGF-β3) has been implicated in scarless healing. In both animal and human models the application of exogenous TGF-β3 causes a reduction in the inflammatory response and improves the architecture of the neodermis. Research into the influence of TGF-β on scarring has tended to focus on fibroblasts. However, keratinocytes play a major role in scarring both indirectly, as a result of their influence over the behaviour of fibroblasts and also by directly influencing wound contraction. Thus, experiments were carried out to investigate the influence of TGF-β3 on the behaviours of a keratinocyte cell line (HaCaT). Incubation with TGF-β3 increased cell spreading and appeared to reduce cell-surface contacts indicated by both SPR imaging and a detachment assay. TGF-β3 also caused a decreased cell alignment response to microcontact printed protein patterns, in part due to the deposition of laminin which is associated with the TGF-β induced cell migration. There is evidence that TGF-β isoforms differentially influence the outcome of wound healing. Similar to the results produce following addition of exogenous TGF-β3, the neutralisation of TGF-β1 and 2 has been shown to reduce scar formation in the adult wounds. During reepithelialisation keratinocytes experience a dynamic environment. Both extracellular matrix proteins and growth factors influence the progression of wound repair which includes both cell migration and proliferation. Few studies have examined collective cell behaviour in response to TGF-β isoforms and ECM coated substrates. Thus both wound closure and cell proliferation assays were conducted for different ECM proteins fibronectin, laminin and collagen type I and for TGF-β1, 2 and 3. Rates of wound closure were significantly reduced on laminin coated substrates while cell proliferation rates were increased. TGF-β2 and 3 induced significant increases in wound closure rates. This appeared to correspond with an increase in the number of cells independently migrating out from the wound margins. Only TGF-β3 caused a significant decrease in cell proliferation over a 4 day period. Laminin332 deposition is central to the reepithelialisation process and is known to be induced in response to TGF-β. Thus experiments were carried out to investigate HaCaT cell laminin332 deposition in response to TGF-β1, 2 and 3. Both an immunofluorescence staining technique and an ELISA based semi-quantification method was used. Following 4 day incubation all TGF-β isoforms significantly increased laminin332 deposition; however TGF-β2 and 3 caused the most significant increases. Integrin receptors enable cell-matrix interactions during wound repair. TGF-β is known to influence the expression of integrin subunits. Thus, experiments were carried out to compare the influence of each TGF-β isoform on the expression of subunits α3, α2, α5, β1 and β4. All TGF-β isoforms significantly increased all subunit expression. TGF-β3 caused the most significant increase in β4 and both TGF-β2 and 3 caused the most significant increase in α2. While there were differences in cell responses to each isoforms, TGF-β3 did not stand out from the other two isoforms. Interestingly, TGF-β2 shared more similarities with TGF-β3 than it did with TGF-β1, in its role in enhancing wound closure and LN332 deposition. These comparative studies have shown that differences exist in the way TGF-β isoforms influence HaCaT cell behaviour, namely migration, laminin deposition and integrin expression.
Functional Investigation of Dual αvβ3 and αllbβ3 Integrin Inhibition in Haematological and Solid Tumour ModelsSheldrake, Helen M.; Patterson, Laurence H.; Elsharif, Amal A.M. (University of BradfordInstitute of Cancer Therapeutics, Faculty of Life Sciences, 2018)Invasion and metastasis of cancer is the leading cause of increased mortality. In addition, haematological malignancies (leukaemia and lymphoma) are a significant cause of morbidity and mortality in both children and adults. Therefore, new treatments which will inhibit cancer progression are required. Integrin adhesion receptors, particularly the RGD-binding integrin subfamily comprising αvβ3, αvβ5, αvβ6, αvβ8, αllbβ3, α5β1, α8β1 and αvβ1 are related to progress and spread of cancer and poor prognosis. Because of the importance of integrin biology in the regulation of cancer dissemination, the integrin receptors are being utilised as targets to regulate cancer progression. The goal of this study was to develop a dual αvβ3/ αIIbβ3 expressing model for testing integrin antagonists. Expression of αv, αIIb, and β3 integrin subunits was characterised using immunofluorescence and flow cytometry in a panel of cell lines. After characterising the expression of αv, αIIb and β3 integrin subunits in inducible and natural expression models (K562 and MCF-7 cells respectively), functional tests for cellular adhesion, detachment and migration were determined. Phorbol 12-myristate 13-acetate (PMA)-treated K562 cells showed increased adhesion on fibrinogen compared to untreated cells. Adhesion of cancer cells (K562 ± PMA and MCF-7) to fibrinogen was inhibited and detachment was induced by the known β3 antagonists, cRGDfV and GR104453. Migration of cancer cells (K562 without PMA and MCF-7) was inhibited by combination of the known β3 antagonists. A panel of 12 novel small molecules developed in the ICT was investigated for cytotoxicity and activity in the validated function assays. ICT9055 was the most potent antagonist in inhibition of cell adhesion, migration, and inducing cell detachment. The data presented in this thesis had selected models and assays for evaluating small molecule integrin antagonists and identified ICT9055 as a promising molecule to develop for further preclinical evaluation.