Stochastic and proliferative events initiated from a single cell can disrupt homeostatic balance and lead to fatal disease processes such as cancer metastasis. To overcome metastasis, it is necessary to detect and quantify sparsely distributed metastatic cells throughout the body at early stages. Here, we demonstrate that clear, unobstructed brain/body imaging cocktails and computational analysis (CUBIC)-based cancer (CUBIC-cancer) analysis with a refractive index (RI)-optimized protocol enables comprehensive cancer cell profiling of the whole body and organs. We applied CUBIC-cancer analysis to 13 mouse models using nine cancer cell lines and spatiotemporal quantification of metastatic cancer progression at single-cell resolution. CUBIC-cancer analysis suggests that the epithelial-mesenchymal transition promotes not only extravasation but also cell survival at metastatic sites. CUBIC-cancer analysis is also applicable to pharmacotherapeutic profiling of anti-tumor drugs. CUBIC-cancer analysis is compatible with in vivo bioluminescence imaging and 2D histology. We suggest that a scalable analytical pipeline with these three modalities may contribute to addressing currently incurable metastatic diseases.

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Transforming growth factor (TGF)-β is known to promote tumor invasion and metastasis. Although bone morphogenetic proteins (BMPs), members of the TGF-β family, are expressed in a variety of human carcinoma cell lines, their roles in tumor progression have not been fully clarified. In this study, we sought to determine the roles of BMPs in the progression of breast cancer bone metastasis using human breast cancer samples and a mouse xenograft model. Immunohistochemical analysis of samples from breast cancer patients as well as a mouse xenograft model of MDA-231-D, highly metastatic human breast cancer cells, revealed phospho-Smad2 and phospho-Smad1/5/8 staining in the nuclei of cancer cells in primary tumor and/or bone metastasis. Using a functional in vivo bioluminescence imaging system, we showed that TGF-β- and BMP-induced transcriptional pathways are active in bone metastatic lesions in vivo. In addition, both TGF-β3 and BMP-2 promoted the motility and invasiveness of the MDA-231-D cells in vitro. Moreover, expression of dominant-negative receptors for TGF-β and/or BMPs in the MDA-231-D cells inhibited invasiveness in vitro and bone metastasis in the xenograft model. These results suggest that BMPs as well as TGF-β promote invasion and bone metastasis of breast cancer.

Transforming growth factor (TGF)‐β signaling has been shown to promote tumor growth and metastasis in advanced cancer. Use of inhibitors of TGF‐β signaling may thus be a novel strategy for treatment of patients with such cancers. In this study, we investigated the effects of a novel TGF‐β type I receptor (TβR‐I) kinase inhibitor, Ki26894, on bone metastasis of a highly bone‐metastatic variant of human breast cancer MDA‐MB‐231 cells, termed MDA‐MB‐231–5a‐D (MDA‐231‐D). Ki26894 blocked TGF‐β signaling in MDA‐231‐D cells, as detected by suppression of phosphorylation of Smad2 and inhibition of TGF‐β‐responsive reporter activity. Moreover, Ki26894 decreased the motility and the invasion of MDA‐231‐D cells induced by TGF‐βin vitro. Ki26894 also suppressed transcription of plasminogen activator inhibitor‐1 (PAI‐1), parathyroid hormone‐related protein (PTHrP), and interleukin‐11 (IL‐11) mRNA of MDA‐231‐D cells, which were stimulated by TGF‐β. X‐ray radiography revealed that systemic Ki26894 treatment initiated 1 day before the inoculation of MDA‐231‐D cells into the left ventricle of BALB/c nu/nu female mice resulted in decreased bone metastasis of breast cancer cells. Moreover, Ki26894 prolonged the survival of mice inoculated with MDA‐231‐D cells compared to vehicle‐treated mice. These findings suggest that TβR‐I kinase inhibitors such as Ki26894 may be useful for blocking the progression of advanced cancers. (Cancer Sci 2007; 98: 127–133)

The mammalian target of rapamycin (mTOR) pathway is commonly activated in human cancers. The activity of mTOR complex 1 (mTORC1) signaling is supported by the intracellular positioning of cellular compartments and vesicle trafficking, regulated by Rab GTPases. Here we showed that tuftelin 1 (TUFT1) was involved in the activation of mTORC1 through modulating the Rab GTPase-regulated process. TUFT1 promoted tumor growth and metastasis. Consistently, the expression of TUFT1 correlated with poor prognosis in lung, breast and gastric cancers. Mechanistically, TUFT1 physically interacted with RABGAP1, thereby modulating intracellular lysosomal positioning and vesicular trafficking, and promoted mTORC1 signaling. In addition, expression of TUFT1 predicted sensitivity to perifosine, an alkylphospholipid that alters the composition of lipid rafts. Perifosine treatment altered the positioning and trafficking of cellular compartments to inhibit mTORC1. Our observations indicate that TUFT1 is a key regulator of the mTORC1 pathway and suggest that it is a promising therapeutic target or a biomarker for tumor progression.

Transforming growth factor (TGF)-β regulates a wide variety of cellular responses, including cell growth arrest, apoptosis, cell differentiation, motility, invasion, extracellular matrix production, tissue fibrosis, angiogenesis, and immune function. Although tumor-suppressive roles of TGF-β have been extensively studied and well-characterized in many cancers, especially at early stages, accumulating evidence has revealed the critical roles of TGF-β as a pro-tumorigenic factor in various types of cancer. This review will focus on recent findings regarding epithelial-mesenchymal transition (EMT) induced by TGF-β, in relation to crosstalk with some other signaling pathways, and the roles of TGF-β in lung and pancreatic cancers, in which TGF-β has been shown to be involved in cancer progression. Recent findings also strongly suggested that targeting TGF-β signaling using specific inhibitors may be useful for the treatment of some cancers. TGF-β plays a pivotal role in the differentiation and function of regulatory T cells (Tregs). TGF-β is produced as latent high molecular weight complexes, and the latent TGF-β complex expressed on the surface of Tregs contains glycoprotein A repetitions predominant (GARP, also known as leucine-rich repeat containing 32 or LRRC32). Inhibition of the TGF-β activities through regulation of the latent TGF-β complex activation will be discussed.