Most patients with colorectal cancer die as a result of the disease spreading to other organs. However, no prevalent mutations have been associated with metastatic colorectal cancers. Instead, ...particular features of the tumour microenvironment, such as lack of T-cell infiltration, low type 1 T-helper cell (T
1) activity and reduced immune cytotoxicity or increased TGFβ levels predict adverse outcomes in patients with colorectal cancer. Here we analyse the interplay between genetic alterations and the tumour microenvironment by crossing mice bearing conditional alleles of four main colorectal cancer mutations in intestinal stem cells. Quadruple-mutant mice developed metastatic intestinal tumours that display key hallmarks of human microsatellite-stable colorectal cancers, including low mutational burden, T-cell exclusion and TGFβ-activated stroma. Inhibition of the PD-1-PD-L1 immune checkpoint provoked a limited response in this model system. By contrast, inhibition of TGFβ unleashed a potent and enduring cytotoxic T-cell response against tumour cells that prevented metastasis. In mice with progressive liver metastatic disease, blockade of TGFβ signalling rendered tumours susceptible to anti-PD-1-PD-L1 therapy. Our data show that increased TGFβ in the tumour microenvironment represents a primary mechanism of immune evasion that promotes T-cell exclusion and blocks acquisition of the T
1-effector phenotype. Immunotherapies directed against TGFβ signalling may therefore have broad applications in treating patients with advanced colorectal cancer.
Recent molecular classifications of colorectal cancer (CRC) based on global gene expression profiles have defined subtypes displaying resistance to therapy and poor prognosis. Upon evaluation of ...these classification systems, we discovered that their predictive power arises from genes expressed by stromal cells rather than epithelial tumor cells. Bioinformatic and immunohistochemical analyses identify stromal markers that associate robustly with disease relapse across the various classifications. Functional studies indicate that cancer-associated fibroblasts (CAFs) increase the frequency of tumor-initiating cells, an effect that is dramatically enhanced by transforming growth factor (TGF)-β signaling. Likewise, we find that all poor-prognosis CRC subtypes share a gene program induced by TGF-β in tumor stromal cells. Using patient-derived tumor organoids and xenografts, we show that the use of TGF-β signaling inhibitors to block the cross-talk between cancer cells and the microenvironment halts disease progression.
A large proportion of colorectal cancers (CRCs) display mutational inactivation of the TGF-β pathway, yet, paradoxically, they are characterized by elevated TGF-β production. Here, we unveil a ...prometastatic program induced by TGF-β in the microenvironment that associates with a high risk of CRC relapse upon treatment. The activity of TGF-β on stromal cells increases the efficiency of organ colonization by CRC cells, whereas mice treated with a pharmacological inhibitor of TGFBR1 are resilient to metastasis formation. Secretion of IL11 by TGF-β-stimulated cancer-associated fibroblasts (CAFs) triggers GP130/STAT3 signaling in tumor cells. This crosstalk confers a survival advantage to metastatic cells. The dependency on the TGF-β stromal program for metastasis initiation could be exploited to improve the diagnosis and treatment of CRC.
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► TGF-β pathway mutant cells require a stromal TGF-β program for metastasis ► CRC patients with low levels of stromal TGF-β program do not relapse ► Pharmacological blockade of TGF-β stromal signaling prevents metastasis initiation ► A TGF-β/IL-11/GP130 signaling cycle confers metastatic organ colonization capacity
Metastasis depends on a gene program expressed by the tumor microenvironment upon TGF-beta stimulation. CRC (Colorectal cancer) cell lines did not induce robust stromal TGF-beta responses when ...injected into nude mice as shown by lack of p-SMAD2 accumulation in tumor-associated stromal cells. To enforce high TGF-beta signaling in xenografts, we engineered CRC cell lines to secrete active TGF-beta. Subcutaneous tumors obtained from HT29-M6TGF-β, KM12L4aTGF-β cells and SW48TGF-β cells contained abundant p-SMAD2+ stromal cells.
We sought to understand the mechanisms behind the potent effect of stromal TGF-beta program on the capacity of colorectal cancer (CRC) cells to initiate metastasis. We discovered that mice ...subcutaneous tumors and metastases generated in the context of a TGF-beta activated microenvironment displayed prominent accumulation of p-STAT3 in CRC cells compared with those derived from control cells. STAT3 signaling depended on GP130 as shown by strong reduction of epithelial p STAT3 levels upon GP130 shRNA-mediated knockdown in CRC cells.
The stereodivergent ring-opening of 2-phenyl oxazaphospholidines with alkyl lithium reagents is reported. N-H oxazaphospholidines derived from both (+)-cis-1-amino-2-indanol and (−)-norephedrine ...provide inversion products in a highly stereoselective process. In contrast, N-Me oxazaphospholidines yield ring-opening products with retention of configuration at the P center, as previously reported by Jugé and co-workers. As a result, from a single amino alcohol auxiliary, both enantiomers of key P-stereogenic intermediates could be synthesized. Theoretical studies of ring-opening with model oxazaphospholidines at the DFT level have elucidated the streochemical course of this process. N-H substrates react in a single step via preferential backside SN2@P substitution with inversion at phosphorus. N-methylated substrates react preferentially via a two-step frontside SN2@P, yielding a ring-opened product in which the nucleophilic methyl binds to P with retention of configuration. DFT calculations have shown that the BH3 unit is a potent directing group to which the methyl lithium reagent coordinates via Li in all the reactions studied.
The purpose of this study was to describe what happens when a portfolio is used as an assessment tool, and determine what actions are required to sustain a portfolio process over time. The overall ...description includes a comprehensive case study, as well as focused identification and analysis of the use of a portfolio process as it relates to assessment, competency identification, self-directed learning, and perceived satisfaction or dissatisfaction with corporate training efforts. These descriptive products were developed from the literature based in education administration, business administration, sociology, learning theory, philosophy, and educational measurements. The notion of a portfolio as an assessment tool is inherently interdisciplinary, and extends across a variety of organizational structures and cultures. In this study, a qualitative constructivist approach to inquiry was used, and a pilot portfolio process was introduced to construction personnel at Zachry Construction Corporation. During the eighteen-month pilot project, data were collected through interviews, observations, and the collection of documents. Findings of the study include descriptions of the attributes associated with the us of a portfolio process. They describe the impact of a portfolio process on individual and corporate improvement processes, perceptions of corporate development efforts, and individual responsibility for developmental activities. Finally, the descriptions address management actions that can facilitate or serve as a barrier to a successful portfolio process.
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