Abstract 2640A: Cell stiffness as a new indicator of diagnosis for human lung cancer cells and their metastasis.

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Abstract Our previous study with atomic force microscopy (AFM) revealed that highly metastatic B16-F10 cells have lower cell stiffness than low metastatic B16-F1 cells, and that treatment of the cells with a green tea polyphenol, EGCG, increased cell stiffness, associated with inhibition of metastasis. Since cell stiffness measured by Young's modulus (Pa) using AFM is attracted the attention as a new indicator of cancer diagnosis, we expanded the study to human lung cancer cell lines, comparing with primary cultured normal bronchial epithelial cells. We found that cell stiffness of lung cancer cell lines was significantly lower than that of human immortalized peripheral lung epithelial cells (HPL1D): Young's moduli for two adenocarcinoma cell lines (A549 and H322) were 2.4 kPa and 2.2 kPa; that of squamous cell carcinoma cell line (H1703): 0.6 kPa; a large cell carcinoma cell line (H1299): 0.8 kPa; and HPL1D: 4.9 kPa. Furthermore, primary cultured normal bronchial epithelial cells (NBEC) established from ten lung cancer patients showed high Young's moduli from 3.0 kPa to 7.4 kPa. These data indicate that soft cell stiffness is a new indicator of diagnosis for lung cancer. Furthermore, it is important to note that H1703 and H1299 cells with low cell stiffness had high motile activity, compared with A549 and H322 cells with high cell stiffness. This indicates that low cell stiffness of lung cancer cell lines was associated with high motility, suggesting high metastatic ability. Treatments with EGF significantly induced transformation of HPL1D cells with morphological change, resulting in significant reduction of cell stiffness from 3.4 kPa to 1.5 kPa. These data suggest that low cell stiffness is induced in carcinogenic process. A histogram of Young's moduli indicates that a cancer cell line is a conglomerate of various cells with varying cell stiffness. In order to study the change of cell stiffness during cell-cycle, we established H1299/Fucci cells by introducing fluorescent-cell-cycle-indicator (Fucci) gene into H1299 cells. Young's moduli for each cell-cycle phase of H1299/Fucci cells were 1.71 kPa for G1, 1.64 kPa for G1→S, 1.55 kPa for S/G2 and 1.64 kPa for M→G1. Thus, changes in cell stiffness were observed depending on cell-cycle regulation, but the difference was small. Based on all data, we think cell stiffness is a dynamic feature of cancer cells, associated with motility and metastasis of lung cancer. Citation Format: Masami Suganuma, Atsushi Takahashi, Tatsuro Watanabe, Hirohiko Akiyama, Yuki Nakajima, Anupom Mondal, Hirota Fujiki. Cell stiffness as a new indicator of diagnosis for human lung cancer cells and their metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2640A. doi:10.1158/1538-7445.AM2013-2640A