Fig. 1

Malignant ascites help cancer cells resist the inhibition of pH changes despite acidic extracellular environment. A Scanning electron microscopy (570X): Ovarian cancer spheroids showed barely any growth in the lower pH group and rapid growth in the slightly alkaline environment (pH range: 6.0, 6.5, 7.0, 7.5). B MTT assay: Malignant ascites increased the metabolism of tumor cells in different pH environments (n = 6, * < 0.05, ** < 0.01). C Adhesion assay: The adhesion of ovarian cancer cells to collagen I, laminin I, collagen IV, fibrinogen, fibronectin, and BSA was inhibited by the acidic environment (n = 3, p < 0.001). Furthermore, malignant ascites at pH 6.5 increased the adhesion of cancer cells (p < 0.05). D Flow cytometry: Apoptotic cell ratio decreases with increasing pH (n = 3, p < 0.05). Malignant ascites decreases the rate of apoptotic cells at different pH, especially in an acidic environment. E Scratch assay: The acidic environment inhibited the migration ability of ovarian cancer cells (n = 3, p < 0.001). Malignant ascites increased the migration of cancer cells