| Summary: | 碩士 === 國立成功大學 === 藥理學研究所 === 94 === Normal tissue cells are generally not viable when suspended in a fluid. Such cells must adhere to a solid support and thus are able to stretch for proliferation. Tumorous tissues however are more rigid due to a stiff extracellular matrix which enables clinicians to diagnose tumors subjectively based on tissue rigidity by palpation. Several studies have suggested that extracellular matrix rigidity influences cell growth, viability, differentiation and motility. However, different rigidities of adhesive collagen substrate affect cellular functions with unclear mechanisms. Here, we cultured the normal cervical epithelial cells and cervical cancer cells on substrates of different rigidities and compared the cell type-specific responses. The culture dish was coated with a very thin layer of collagen gel (control group) or overlaid with collagen gel (soft substrate). Detected by the dynamic mechanical analyzer, the substrate rigidity of control group is more than 1 giga pascal, similar to that of culture dish without any coated substances. In contrast, overlaying the culture dish with collagen gel remarkably decreased the substrate rigidity to 30–100 pascals. Normal cervical epithelial cells contracted as they grew on collagen gel and the apoptotic bodies obviously appeared with time. μ-calpain was activated when normal cervical epithelial cells cultured on collagen gel. In addition, soft substrate caused elevated cytosolic Ca2+, Ca2+ overload in endoplasmic reticulum and upregulation of capacitative calcium entry. Ca2+ chelator partially rescued the collagen-gel induced apoptosis by inhibiting μ-calpain activation. In contrast, for cervical cancer cells cultured either on collagen gel or on gel-coated dish, there was no significant change in cell morphology and positive Annexin V staining. In conclusion, soft substrate regulates growth and apoptosis of normal cervical epithelial cells but not cervical cancer cells by calpain activation via the disturbance of Ca2+ homeostasis.
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