Browsing by Author "Dhawan, Priyal"

The significance of adhesion to the basement membrane (BM) for the growth and survival of healthy mammary epithelial cells is well-established. In ductal carcinoma in situ (DCIS), a non-invasive form of breast cancer, luminal cells detach from the BM and proliferate within the ductal lumen of the mammary gland. This suggests that malignant cells are capable of evading detachment induced cell death, called anoikis during DCIS. The alterations that contribute to anoikis resistance may be essential for anchorage-independent survival, a phenomenon that remains largely unexplored in the context of BM. Hence, in this study, I aimed to investigate the association between anchorage-independent survival of breast cancer cells and the expression of BM components. I utilized a low-adhesion 3D suspension culture devoid of any matrix to evaluate the efficiency of mammosphere formation in luminal A and triple-negative breast cancer cell lines. To understand the ability of cancer cells to survive in an anchorage-independent environment, I investigated the expression profiles of BM components (including laminins and type IV collagen) across various breast cancer cell lines. Gene expression analysis of BM components was conducted in conventional 2D monolayer cultures, while immunofluorescence analysis was performed on mammospheres or single cell clusters derived from low-adhesion 3D cultures. Furthermore, to explore their functional significance, I examined the effect of laminin α5 (LAMA5) downregulation on the spheroid formation ability of luminal A cell line ZR75-1. The primary results of the study highlighted the ability of breast cancer cells to survive in low anchorage conditions by forming mammospheres or as single-cell clusters. Significant variations in the expression of BM components were observed across breast cancer cell lines and within the subtypes. Moreover, I observed the atypical expression and localization of BM components produced by the various breast cancer cell lines in the 3D culture. The potential functional relevance of BM was demonstrated by the decreased mammosphere-forming ability of the ZR75-1 with LAMA5 downregulation. Although further investigations are needed, these observations suggest a crucial role of BM produced by tumour cells in facilitating anoikis resistance and anchorage-independent survival of cancer cells.