Browsing by Author "Fourie, Carla"

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    The paracrine effects of fibroblasts on Doxorubicin-treated breast cancer cells
    (Stellenbosch : Stellenbosch University, 2019-04) Fourie, Carla; Engelbrecht, Anna-Mart; Davis, Tanja; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Introduction: Breast cancer is frequently diagnosed in women in both developed and developing countries and poses a major health problem throughout the world. The current standard treatment for breast cancer patients is radiation, surgery and chemotherapy or a combination of surgery with chemotherapy. The unresponsiveness of cancer cells to chemotherapeutics, however, is still a main concern. During chemotherapeutic treatment with Doxorubicin, normal and healthy neighbouring cells are also damaged. Apoptotic or senescent fibroblasts in the tumour microenvironment can then secrete a variety of bioactive molecules which promote tumour growth, metastasis and drug resistance. Methods: Mouse embryonic fibroblasts (MEFs) were cultured and treated with Doxorubicin to induce apoptosis and senescence respectively. An SA-ß-gal stain was used to determine the number of senescent cells in the cell population and expression of apoptotic and senescent markers were determined through western blotting. Conditioned media was collected from the MEFs after apoptosis and senescence induction and used to assess the paracrine effects between fibroblasts and E0771 cells. Results and discussion: Doxorubicin (1 μM) was able to significantly induce apoptosis in MEFs after 24 hours. During senescence induction, 2 μM of Doxorubicin treatment for 4 hours was unable to induce 80% of senescence in the MEF population. The western blot analyses show that the expression of many apoptosis and senescence markers significantly increased or decreased after Doxorubicin treatment. Furthermore, the results indicate that senescent fibroblasts (56%) were able to significantly increase cell viability in E0771 cells following treatment with Doxorubicin. Conclusion: Our results highlight the fact that the tumour microenvironment is extremely complex and how important it is that chemotherapeutic agents such as Doxorubicin should specifically target cancer cells. Once healthy, neighbouring stromal cells such as fibroblasts are affected by chemotherapeutic agents, they have the ability to secrete paracrine factors that enhance breast cancer growth and induce therapeutic resistance by evading cell death.
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    The role of Serum Amyloid A in NLRP3 inflammasome signalling in breast and colon cancer
    (Stellenbosch : Stellenbosch University, 2022-04) Fourie, Carla; Engelbrecht, Anna-Mart; Davis, Tanja; De Villiers, Willem J. S.; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Introduction: Cancer is a complex disease with multiple interactions targeting the organism on cellular, tissue and systemic levels. The main research focus for the past decades has been on the genome and on the molecular level where signaling pathways were dissected for the development of targeted therapies. However, in order to develop more efficient therapeutic regimes, a better understanding on systemic level is required. Over the past few years, the role of serum amyloid A (SAA) has gathered significant evidence which highlights its role in the pathogenesis of several cancers, including breast and colorectum carcinomas. To date, SAA has been shown to bind to several pattern recognition receptors, which might suggest that inflammasomes play a role in the tumour-promoting properties of SAA. Inflammasomes are cytoplasmic multiprotein complexes characterized by a sensor protein, an adaptor protein, and inflammatory caspases. However, the role of inflammasomes in cancer remain controversial. The aim of this study was therefore to investigate the role of SAA in inflammasome signaling in breast and colon cancer. Methods: In this 3-part animal study, tissues were subjected to immunoblotting, real-time PCR, haematoxylin and eosin staining and immunohistochemistry. For the first inflammatory model, wild-type and SAA double knockout C57BL/6 mice received 2.5% dextran sulfate sodium, which was administered for a total of 5 days. To assess tumourigenesis, colitis-associated cancer and triple negative breast cancer models were used, respectively. For colitis- associated cancer, wild-type and SAA double knockout C57BL/6 mice received an intraperitoneal injection of 12.5 mg/kg azoxymethane. After one week, dextran sulfate sodium treatment was administered at a concentration of 2.5% for a total of 5 days, followed by a recovery period of 16 days. Dextran sulfate sodium treatment was administered for a total of 3 cycles. Triple negative breast tumours were established in wild-type and SAA double knockout C57BL/6 mice by injecting EO771 cells subcutaneously at the fourth mammary fat pad. The experimental endpoint was reached when tumour volumes reached 300-400 mm3. Results: In this study we have showed that in an in vivo model of dextran sulfate sodium induced colitis, SAA ablation exerted pro-inflammatory properties independent of the NLRP3 inflammasome. The ablation of serum amyloid A1/2 was associated with the increased expression of pro- inflammatory cytokines. In contrast, in an in vivo colitis-associated cancer and in a triple negative breast cancer model, the ablation of SAA suppressed canonical NLRP3 inflammasome activation, which was associated with anti-inflammatory properties. These findings suggest that during tumourigenesis, SAA functions as an endogenous damage associated molecular pattern in the tumour microenvironment. Conclusion: Here we show for the first time, in models of CAC and TNBC, the novel role of SAA in the activation of the NLRP3 inflammasome and the generation of pro-inflammatory cytokines, two mechanisms known to promote tumour development and metastasis. This study emphasizes the notion that the tumour-induced systemic environment acts as a critical regulator of cancer progression and metastasis. In conclusion, simultaneously targeting SAA and NLRP3 components could be beneficial for cancer treatments.
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    Serum amyloid A and inflammasome activation : a link to breast cancer progression?
    (Elsevier, 2020-10-27) Fourie, Carla; Shridas, Preetha; Davis, Tanja; de Villiers, Willem J. S.; Engelbrecht, Anna-Mart
    Breast cancer is the most frequently diagnosed cancer in women globally. Although there have been many significant advances made in the diagnosis and treatment of breast cancer, numerous unresolved challenges remain, which include prevention, early diagnosis, metastasis and recurrence. The role of inflammation in cancer development is well established and is believed to be one of the leading hallmarks of cancer progression. Recently, the role of the inflammasome, a cytosolic multiprotein complex, has received attention in different cancers. By contributing to the activation of inflammatory cytokines the inflammasome intensifies the inflammatory cascade. The inflammasome can be activated through several pathways, which include the binding of pattern associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) to toll-like receptors (TLRs). Serum amyloid A (SAA), a non-specific acute-phase protein, can function as an endogenous DAMP by binding to pattern recognition receptors like TLRs on both breast cancer cells and cancer associated fibroblasts (CAFs). SAA can thus stimulate the production of IL-1β, thereby creating a favourable inflammatory environment to support tumour growth. The aim of this review is to highlight the possible role of SAA as an endogenous DAMP in the tumour microenvironment (TME) thereby promoting breast cancer growth through the activation of the NLRP3 inflammasome.