Significance of cancer-associated fibroblasts in the regulation of gene expression in the leading cells of invasive lung cancer

Park

Clinical Cancer Research

et al. 2013

114

Purpose: Metastatic relapse of primary lung cancer leads to therapeutic resistance and unfavorable clinical prognosis; therefore, identification of key molecules associated with metastatic conversion has significant clinical implications. We previously identified a link between early brain metastasis of lung adenocarcinoma and amplification of the a-smooth muscle actin (ACTA2) gene. The aim of present study was to investigate the prognostic and functional significance of ACTA2 expression in cancer cells for the metastatic potential of lung adenocarcinomas.Experimental Design: ACTA2 expression was analyzed in tumor cells from 263 patients with primary lung adenocarcinomas by immunohistochemistry, and was correlated with clinicopathologic parameters. The expression of ACTA2 in human lung adenocarcinoma cells was modulated with short hairpin RNAs (shRNA) and siRNAs specifically targeting ACTA2.Results: The patients with lung adenocarcinomas with high ACTA2 expression in tumor cells showed significantly enhanced distant metastasis and unfavorable prognosis. ACTA2 downregulation remarkably impaired in vitro migration, invasion, clonogenicity, and transendothelial penetration of lung adenocarcinoma cells without affecting proliferation. Consistent with the in vitro results, depletion of ACTA2 in human lung adenocarcinoma PC14PE6 cells significantly reduced their metastatic potential without altering their tumorigenic potential. Expression of c-MET and FAK in lung adenocarcinoma cells was also reduced by ACTA2-targeting siRNAs and shRNAs, and was accompanied by a loss of mesenchymal characteristics.Conclusions: These findings indicate that ACTA2 regulates c-MET and FAK expression in lung adenocarcinoma cells, which positively and selectively influence metastatic potential. Therefore, ACTA2 could be a promising prognostic biomarker and/or therapeutic target for metastatic lung adenocarcinoma.

Section: Discussionmentioning

confidence: 68%

Alpha-Smooth Muscle Actin (ACTA2) Is Required for Metastatic Potential of Human Lung Adenocarcinoma

Park

Clinical Cancer Research

et al. 2013

114

“…One of these proteins, integrin β1, was evaluated in a series of studies addressing collective cancer invasion82133. Although in previous reports, integrin β1 was highly expressed in the front cells of cancer collectives, the mechanism for integrin β1's role in front cells was not well understood.…”

Section: Discussionmentioning

confidence: 99%

“…PI3K is a well-characterized contributor to cell survival26. Recently, an anti-apoptosis protein, Bcl-2, was shown to be highly expressed in the leading cells of cancer collectives8. As such, proteins involved in cell survival may not only regulate survival, but also leader cell migration.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Leader cells regulate collective cell migration via Rac activation in the downstream signaling of integrin β1 and PI3K

Yamaguchi

Mizutani

Kawabata

et al. 2015

Sci Rep

137

156

Collective cell migration plays a crucial role in several biological processes, such as embryonic development, wound healing, and cancer metastasis. Here, we focused on collectively migrating Madin-Darby Canine Kidney (MDCK) epithelial cells that follow a leader cell on a collagen gel to clarify the mechanism of collective cell migration. First, we removed a leader cell from the migrating collective with a micromanipulator. This then caused disruption of the cohesive migration of cells that followed in movement, called “follower” cells, which showed the importance of leader cells. Next, we observed localization of active Rac, integrin β1, and PI3K. These molecules were clearly localized in the leading edge of leader cells, but not in follower cells. Live cell imaging using active Rac and active PI3K indicators was performed to elucidate the relationship between Rac, integrin β1, and PI3K. Finally, we demonstrated that the inhibition of these molecules resulted in the disruption of collective migration. Our findings not only demonstrated the significance of a leader cell in collective cell migration, but also showed that Rac, integrin β1, and PI3K are upregulated in leader cells and drive collective cell migration.

“…Probes targeting β-actin mRNA, miR-21, miR-23b, and a random negative control probe are designed and optimized for maximal target binding affinity. The ability of the dsLNA probe to detect miR-21 and miR-23b levels is examined in MCF-7 epithelial cancer cells by measuring the probe’s response to TGF-β, an anti-proliferative cytokine that plays important roles in collective cell migration and epithelial-mesenchymal transition [21, 22]. TGF-β increases mature miR-21 through Dicer splicing of pri-miR-21 to pre-miR-21, as well as inhibits miR-23b expression at the transcriptional level [23, 24].…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal dynamics of microRNA during epithelial collective cell migration

2015

MicroRNAs (miRNAs) are small, noncoding RNAs variably involved in a wide variety of developmental and regenerative programs. Techniques for monitoring the spatiotemporal expression of miRNA in living cells are essential to elucidate the roles of miRNA during these complex regulatory processes. The small size, low abundance, sequence similarity, and degradation susceptibility of miRNAs, however, make their detection challenging. In this study, we detail a double-stranded locked nucleic acid (dsLNA) probe for detecting intracellular miRNAs during epithelial collective migration. The dsLNA probe is capable of detecting the dynamic regulation and dose-dependent modulation of miRNAs. The probe is applied to monitor the spatial distribution of miRNA expression of a migrating epithelium. Our results reveal a gradient of miRNA over the first one hundred microns from the leading edge and show the involvement of miR-21 in the complex regulation of transforming growth factor beta modulated epithelial migration. With its ease of use and capacity for real-time monitoring of miRNAs in living cells, the dsLNA probe carries the potential for studying the function and regulation of miRNA in a wide spectrum of complex biological processes.