Browsing by Author "Peres, Jade"

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    The role of T-box transcription factor TBX3 in rhabdomyosarcoma
    (2016) Sims, Danica Anne; Prince, Sharon; Peres, Jade
    Cancer remains one of the leading causes of death worldwide due to late diagnosis and ineffective treatment options. To address this problem requires the elucidation of the molecular mechanisms, including the signaling pathways and transcription factors that drive cancer initiation and progression. In this regard, our laboratory has been particularly interested in the embryonically important T - box family of transcription factors which has been heavily implicated in promoting initiation and progression of a long list of cancers. For example, the overexpression of the T - box factor TBX3, has been reported to function in promoting immortalization, migration, invasion and tumour formation in a number of epithelial - derived malignancies. Furthermore, our laboratory recently reported that TB X3 is also overexpressed in a wide range of sarcoma subtypes including rhabdomyosarcomas. This suggests that TBX3 may also contribute to the development and/or progression of sarcomas and potentially may serve as a biomarker for their diagnosis and targete d therapy. This is exciting because sarcomas are diverse and heterogeneous cancers with varying clinical behaviours, high rates of metastasis and recurrence and are notoriously resistant to current chemotherapies. However, whether TBX3 is a molecular drive r of these mesenchymal - derived cancers remains to be determined. This project therefore aimed to elucidate the role of TBX3 overexpression in embryonal rhabdomyosarcomas (ERMS) which is the most common soft tissue sarcoma in children and adolescents. To this end, ERMS cell culture models were established in which TBX3 was either stably knocked down or stably overexpressed and the resulting cells were tested for several features of the cancer phenotype using in vitro and in vivo experiments. The results show that TBX3 promotes cell proliferation, anchorage independent growth and cell migration in vitro and tumour formation and invasion in vivo. This study also provides evidence that nucleolin binds to, and co - operates with, TBX3 to promote proliferation and migration of ERMS cells. Furthermore, data from initial experiments reveal that Hsc70 interacts with TBX3, to possibly increase its protein stability, and that oncogenic c - Myc and AKT 1 positively regulat e TBX3 levels in ERMS. This, albeit preliminary data, suggest that Hsc70, c - Myc and AKT1 are responsible, in part, for the overexpression of TBX3 in ERMS. Together findings from this study implicate TBX3 as an oncogene in ERMS and suggest that TBX3, nucleolin, Hsc70, c - Myc and AKT may be used in combination as biomarkers for the diagnosis and targeted therapy of ERMS.
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    Studying the Role of Mechanical Properties of Cancer Cells in Tumour Detachment, Migration and Secondary Tumour Formation
    (2021) Higgins, Ghodeejah; Franz, Thomas; Peres, Jade; Zaman, Muhammad
    Tumour cell detachment, migration and invasion, and secondary tumour formation are critical oncogenic processes during cancer metastasis. Although several molecular mechanisms have been reported to facilitate metastasis, it remains elusive how cellular mechanics contribute to these processes. The goal of this thesis was therefore to reveal and understand how cell mechanics contribute to different stages of the metastatic cascade. Directed cell migration was mechanically induced through 2D in vitro scratch assays whereas tumour cell detachment and tumour formation processes were modelled in 3D in vitro collagen matrices using cell spheroid invasion assays or through self-assembly of cells in isolation (i.e., cluster formation) respectively. Metastatic breast cancer cells were used for the tumour detachment and invasion process, while all other processes were studied on melanoma cells of radial growth phase (RGP), vertical growth phase (VGP) and metastatic (MET) stage. To determine intracellular stiffness, particle tracking microrheology was used in 2D and 3D contexts. Protein content of actin and tubulin was quantified with Western blotting and the oncogenic factor TBX3 was assessed with immunofluorescence techniques. The results show that melanoma progression led to decreased stiffness of cells in isolation in 2D, but increased cell stiffness in 3D. For cells in clusters, stiffness was similar across disease stages, however, cluster formation entailed decreased cell stiffness. Cell volume, cytoskeletal content and mitochondrial dynamics were implicated as primary factors that contribute to altered cell stiffness. Further, TBX3 levels in VGP and MET cells in isolation were overexpressed in compliant matrices but were depleted in rigid matrices. For cell clusters, TBX3 levels of MET but not of VGP cells decreased in rigid matrices. Based on the findings on metastatic breast cancer cells, decreased cell stiffness is proposed to drive the detachment of cells from a tumour, and increased cell stiffness facilitates the subsequent migration and invasion. However, the adjustment of the stiffness of invading cells was dependent on matrix rigidity. Taken together, the adjustment of cancer cell properties, both mechanical and molecular, emphasizes the importance of studying cancer cells in their physiologically relevant context. In addition to accounting for changes in dimensionality, it is equally important to consider how cancer cells modify their biomechanical and molecular properties to orchestrate complex processes during different stages of the metastatic cascade.
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    The T-box transcription factor TBX3 drives proliferation by direct repression of the p21WAF1 cyclin-dependent kinase inhibitor
    (BioMed Central, 2016-04-22) Willmer, Tarryn; Hare, Shannagh; Peres, Jade; Prince, Sharon
    Background: TBX3, a member of the T-box family of transcription factors, is essential in development and has emerged as an important player in the oncogenic process. TBX3 is overexpressed in several cancers and has been shown to contribute directly to tumour formation, migration and invasion. However, little is known about the molecular basis for its role in development and oncogenesis because there is a paucity of information regarding its target genes. The cyclin-dependent kinase inhibitor p21WAF1 plays a pivotal role in a myriad of processes including cell cycle arrest, senescence and apoptosis and here we provide a detailed mechanism to show that it is a direct and biologically relevant target of TBX3. Results: Using a combination of luciferase reporter gene assays and in vitro and in vivo binding assays we show that TBX3 directly represses the p21WAF1 promoter by binding a T-element close to its initiator. Furthermore, we show that the TBX3 DNA binding domain is required for the transcriptional repression of p21WAF1 and that pseudo-phosphorylation of a serine proline motif (S190) located within this domain may play an important role in regulating this ability. Importantly, we demonstrate using knockdown and overexpression experiments that p21WAF1 repression by TBX3 is biologically significant and required for TBX3-induced cell proliferation of chondrosarcoma cells. Conclusions: Results from this study provide a detailed mechanism of how TBX3 transcriptionally represses p21WAF1 which adds to our understanding of how it may contribute to oncogenesis.
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    The T-box transcription factor, TBX3, is sufficient to promote melanoma formation and invasion
    (BioMed Central Ltd, 2013) Peres, Jade; Prince, Sharon
    The T-box transcription factor, TBX3, is overexpressed in several cancers and has been proposed as a chemotherapeutic target. Several lines of evidence suggest that TBX3 may be a key contributor to malignant melanoma, a highly aggressive and intractable disease. Using in vitro and in vivo assays we demonstrate here for the first time that overexpressing TBX3 in non-tumourigenic early stage melanoma cells is sufficient to promote tumour formation and invasion. Furthermore, we show that TBX3 may play an important role as a reciprocal switch between substrate dependent cell proliferation and tumour invasion.