blister and Lung-Neoplasms

Cortical actin is a thin layer of filamentous (F-)actin that lies beneath the plasma membrane, and its role in pathophysiology remains unclear. We investigated the subcellular localization of cortical actin by the histopathological and experimental studies of lung adenocarcinomas.. The subcellular localization of cortical actin was studied in surgically resected lung adenocarcinomas tissues and in 3-dimensionally cultured lung adenocarcinoma A549 cells.. In normal type II alveolar cells and the bronchiolar epithelium, cortical actin was localized to the apical-side cytoplasm. In invasive adenocarcinoma cells, cortical actin was frequently localized to the matrix side. The degree of cortical actin localized to the matrix side was associated with the loss of basement membrane and a poor prognosis. In A549 cell spheroids cultured in a type I collagen and basement membrane extract Matrigel™ mixed gel, cortical F-actin was localized to the matrix side with phosphorylated myosin light chain. Super-resolution and electron microscopy results suggest that compact wrinkling of the plasma membrane by myosin-mediated F-actin contraction is an explanation for cortical actin accumulation at the matrix side. The myosin II inhibitor blebbistatin suppressed the 3-dimensional collective migration of A549 cells induced by constitutively active Cdc42 and MT1-MMP.. Cortical actin accumulation at the matrix-side cytoplasm of cancer cells occurs in invasive lung adenocarcinomas and it possibly participates in the migration of cancer cells through myosin-mediated contraction.

Topics: A549 Cells; Actins; Adenocarcinoma; Adenocarcinoma of Lung; Cell Membrane; Cell Movement; Cytoplasm; Heterocyclic Compounds, 4 or More Rings; Humans; Immunohistochemistry; Lung Neoplasms; Myosins; Neoplasm Invasiveness; Neoplasm Metastasis; Prognosis

Tumor metastasis is one of the main causes of mortality among patients with malignant tumors. Previous studies concerning tumor metastasis have merely focused on the cancer cells in the tumor. However, an increasing number of studies show that the tumor microenvironment plays a vital role in the progression of cancer, particularly in tumor metastasis. Since fibroblasts and adipocytes are two of the most representative mesenchymal cells in the tumor microenvironment, we established a hypoxia-induced cancer-associated fibroblast (CAF) model and a chemically induced adipocyte model to reveal the effect of the microenvironment on cancer development. In these models, the conditioned medium from the tumor microenvironment was found to significantly promote the migration of human lung cancer cell line 95D and regulate the expression of non-muscle myosin IIA (NMIIA), which is consistent with results in the published literature. Then, we confirmed the hypothesis that the tumor microenvironment can regulate NMIIA in cancer cells and facilitate migration by using the non-muscle myosin II inhibitor, blebbistatin. Thus, this is the first report that the tumor microenvironment can promote cancer cell migration by regulating the expression of NMIIA. Our present data also indicated that DT-13, the saponin monomer 13 of dwarf lilyturf tuber, inhibited cancer cell migration in the tumor microenvironment model. Further results showed that DT-13 exhibited anti-migratory effects by inhibiting the c-raf/ERK1/2 signaling pathway. Consequently, our research confirmed that DT-13 significantly inhibited 95D cell migration in vitro, indicating the potential anti-metastatic effect of DT-13 on lung cancer and the scientific basis for drug development.

Topics: Cell Line, Tumor; Cell Movement; Fibroblasts; Heterocyclic Compounds, 4 or More Rings; Humans; Hypoxia; Lung Neoplasms; MAP Kinase Signaling System; Molecular Motor Proteins; Myosin Heavy Chains; Proto-Oncogene Proteins c-raf; Saponins; Signal Transduction; Tumor Microenvironment

Microenvironment stiffening plays a crucial role in tumorigenesis. While filopodia are generally thought to be one of the cellular mechanosensors for probing environmental stiffness, the effects of environmental stiffness on filopodial activities of cancer cells remain unclear. In this work, we investigated the filopodial activities of human lung adenocarcinoma cells CL1-5 cultured on substrates of tunable stiffness using a novel platform. The platform consists of an optical system called structured illumination nano-profilometry, which allows time-lapsed visualization of filopodial activities without fluorescence labeling. The culturing substrates were composed of polyvinyl chloride mixed with an environmentally friendly plasticizer to yield Young's modulus ranging from 20 to 60 kPa. Cell viability studies showed that the viability of cells cultured on the substrates was similar to those cultured on commonly used elastomers such as polydimethylsiloxane. Time-lapsed live cell images were acquired and the filopodial activities in response to substrates with varying degrees of stiffness were analyzed. Statistical analyses revealed that lung cancer cells cultured on softer substrates appeared to have longer filopodia, higher filopodial densities with respect to the cellular perimeter, and slower filopodial retraction rates. Nonetheless, the temporal analysis of filopodial activities revealed that whether a filopodium decides to extend or retract is purely a stochastic process without dependency on substrate stiffness. The discrepancy of the filopodial activities between lung cancer cells cultured on substrates with different degrees of stiffness vanished when the myosin II activities were inhibited by treating the cells with blebbistatin, which suggests that the filopodial activities are closely modulated by the adhesion strength of the cells. Our data quantitatively relate filopodial activities of lung cancer cells with environmental stiffness and should shed light on the understanding and treatment of cancer progression and metastasis.

Topics: Cell Adhesion; Cell Line, Tumor; Cell Survival; Heterocyclic Compounds, 4 or More Rings; Humans; Lung Neoplasms; Pseudopodia; Tumor Cells, Cultured

We show that in melanoma cells oncogenic BRAF, acting through MEK and the transcription factor BRN2, downregulates the cGMP-specific phosphodiesterase PDE5A. Although PDE5A downregulation causes a small decrease in proliferation, its major impact is to stimulate a dramatic increase in melanoma cell invasion. This is because PDE5A downregulation leads to an increase in cGMP, which induces an increase in cytosolic Ca(2+), stimulating increased contractility and inducing invasion. PDE5A downregulation also this leads to an increase in short-term and long-term colonization of the lungs by melanoma cells. We do not observe this pathway in NRAS mutant melanoma or BRAF mutant colorectal cells. Thus, we show that in melanoma cells oncogenic BRAF induces invasion through downregulation of PDE5A.

Topics: Animals; Calcimycin; Calcium; Cardiac Myosins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 5; Down-Regulation; Gene Expression; Gene Expression Regulation, Neoplastic; Heterocyclic Compounds, 4 or More Rings; Homeodomain Proteins; Humans; Lung Neoplasms; Melanoma; Mice; Mice, Nude; Myosin Light Chains; Neoplasm Invasiveness; Phosphodiesterase 5 Inhibitors; Phosphorylation; POU Domain Factors; Promoter Regions, Genetic; Protein Binding; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; RNA, Small Interfering; Transplantation, Heterologous