Analysis of the morphological changes in the cell nucleus under acid stress environment for pathological diagnosis

It has recently been pointed out that the shape of the cell nucleus is possibly controlled by forces generated inside and outside the nucleus. It has also been known that the cell nucleus shows an unusual distorted shape with some disease, such as canceration or progeria. Since the nucleus with distorted shape may be resulted in a disturbance of force balances around the nucleus, it is possible that the shape change of the nucleus is related to the functional change of the cells. In addition, cells in living tissues are exposed to an acidic environment with tumor formation and hypoxia, and they change their structures due to the acidic environment. Thus it is possible to predict the canceration by analyzing the structural change of cells under acidic stress exposure. In this study, we first established a method for analyzing the shape of the nucleus, and investigated the response of the normal fibroblasts (3T3 cells) and cervical cancer cells (HeLa cells) to acid stress, focusing on the change in the shape of the nucleus. We found that the nucleus elongation and intranuclear DNA condensation were significantly observed only in HeLa cells in an acidic environment although both types of cells elongated their adhesion area and developed their actin filaments. These results indicate that mechanical responses of nucleus under acidic stress exposure are quite different in cell types.