Masters Degrees (Physiological Sciences)

Permanent URI for this collection

https://scholar.sun.ac.za/handle/10019.1/3772

Browse

Browsing Masters Degrees (Physiological Sciences) by Author "Conradie, Daleen"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Dynamic interactions between skeletal muscle and breast cancer cells following chemotherapeutic treatment
    (Stellenbosch : Stellenbosch University, 2019-04) Conradie, Daleen; Engelbrecht, Anna-Mart; Isaacs, Ashwin; Davis, Tanja; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Background: Breast cancer is the most common cancer found among women of South Africa with the prominent effective form of treatment being chemotherapy. Many cancer patients receiving chemotherapeutic treatment experience skeletal muscle wasting, however, the contribution of muscle wasting to the metastatic properties of breast cancer and response to current treatment strategies has not yet been fully investigated. The aims of this study were to investigate the reciprocal interactions between mouse breast cancer cells (E0771) and mouse myotubes (C2C12) as well as the effects of doxorubicin (DXR) on these interactions. Methods: Conditioned media was collected from two separate cycles. The initial cycle of conditioned media was collected from E0771 breast cancer cells after treatment with/without 1.6 μM of DXR. Myotubes were then treated with/without DXR as well as conditioned media collected during the initial cycle from the E0771 cells. A new series of E0771 cells were then treated with/without DXR as well as with the second cycle of conditioned media collected from the myotubes. Mitochondrial integrity of myotubes was investigated using MitoSOX™ stain analysis while myotube cell viability and integrity was assessed using a Cell Tracker™ stain analysis. Cell viability of E0771 cells was assessed with an MTT assay and the migratory properties (wound closure) using a migration scratch assay. Western blot analyses were used to determined alterations in proliferation, apoptotic, and epithelial-mesenchymal transition (EMT) signaling pathways. Results: Treatment of myotubes with 1.6 μM of DXR significantly induced mitochondrial ROS production (5.580 ± 0.4, p<0.001) when compared to Control but myotube integrity was maintained. Treatment of E0771 cells with 1.6 μM of DXR compared to Control significantly decreased cell viability (60.354% ± 1.237, p<0.001), significantly increased the phosphor/total ERK expression ratio (3.946 ± 0.520, p<0.001), and significantly decreased the cleaved/total PARP expression ratio (0.651 ± 0.027, p<0.001). Additionally, a significant increase in the percentage of wound closure was also observed in the DXR group (16.049% ± 1.11, p<0.01) compared to Control after 24-hours. E0771 cells treated with myotube conditioned media after treatment of DXR (C.DXR), induced a significant decrease in expression of the cleaved/total PARP ratio (0.662 ± 0.097, p<0.01) as well as a significant difference in percentage of wound closure (17.19 ± 0.758, p<0.001) compared to C.Control. Following treatment of the E0771 cells with myotube conditioned media, harvested after the treatment of conditioned media from DXR treated E0771 cells (C.C.DXR), a significant increase in cell viability (121.743% ± 3.442, p<0.05) when compared to C.C.Control. Additionally, comparison of C.C.DXR to C.C.Control observed a significant decrease in expression of total Akt (65.554% ± 17.55, p<0.05), MCM2 (55.167% ± 14.64, p<0.05), and the cleaved/total PARP ratio (0.456 ± 0.111, p<0.001) was observed. Conclusion: Investigation of the dynamic interactions between myotubes and breast cancer cells revealed novel evidence of the influence of the myotube environments on cancer progression. Our study also revealed novel evidence that this myotube environment significantly affected the response of breast cancer cells to the chemotherapeutic treatment of DXR. These findings identified new mechanisms that may promote breast cancer metastasis, which can be utilized to improve chemotherapy in cancer patients.