Abstract The Ras/Raf/MEK pathway represents an important oncogenic signaling pathway in gastrointestinal malignancies, including pancreatic cancer. Although activating B-Raf mutations are infrequent in pancreatic cancer, we hypothesized that targeting Raf could be valuable for therapy of this cancer entity. Moreover, as vascular endothelial growth factor receptor 2 (VEGFR2) is involved in tumor angiogenesis, we sought to investigate the effects of dual inhibition of Raf and VEGFR2 on pancreatic tumor growth, vascularization, and metastasis. Effects of a Raf/VEGFR2 inhibitor (NVP-AAL881) on pancreatic cancer cells, endothelial cells, and vascular smooth muscle cells were determined by Western blotting, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis, and migration assays, respectively. Changes in the expression of VEGF-A or survivin were investigated by ELISA and/or real-time PCR. The growth-inhibitory effects of Raf/VEGFR2 inhibition were additionally evaluated in orthotopic tumor models. Results showed that various Raf isoforms were activated in pancreatic cancer cells and NVP-AAL881 diminished the activation of MEK, Akt, Erk, and also STAT3. Moreover, dual inhibition of Raf/VEGFR2 significantly reduced VEGF expression and impaired cancer cell migration. Importantly, besides blocking VEGF-induced Erk and SAPK phosphorylation in endothelial cells, the Raf inhibitor diminished STAT3 phosphorylation, independent of a VEGFR2 blockade, and reduced the expression of survivin. In addition, cell proliferation and migration of both endothelial cells and vascular smooth muscle cells were significantly reduced. In vivo, blocking Raf/VEGFR2 significantly inhibited orthotopic tumor growth and vascularization and reduced cancer metastasis. In conclusion, blocking Raf exerts growth-inhibitory effects on pancreatic tumor cells, endothelial cells, and pericytes and elicits antiangiogenic properties. Dual targeting of Raf and VEGFR2 appears to be a valid strategy for therapy of pancreatic cancer. [Mol Cancer Ther 2008;7(11):3509–18]
Abstract Circular RNAs (circRNAs) encompass a widespread and conserved class of RNAs, which are generated by back-splicing of downstream 5′ to upstream 3′ splice sites. CircRNAs are tissue-specific and have been implicated in diseases including cancer. They can function as sponges for microRNAs (miRNAs) or RNA binding proteins (RBPs), for example. Moreover, some contain open reading frames (ORFs) and might be translated. The functional relevance of such peptides, however, remains largely elusive. Here, we report that the ORF of circZNF609 is efficiently translated when expressed from a circZNF609 overexpression construct. However, endogenous proteins could not be detected. Moreover, initiation of circZNF609 translation is independent of m6A-generating enzyme METTL3 or RNA sequence elements such as internal ribosome entry sites (IRESs). Surprisingly, a comprehensive mutational analysis revealed that deletion constructs, which are deficient in producing circZNF609, still generate the observed protein products. This suggests that the apparent circZNF609 translation originates from trans-splicing by-products of the overexpression plasmids and underline that circRNA overexpression constructs need to be evaluated carefully, particularly when functional studies are performed.
Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with adverse outcomes that have barely improved over the last decade. About half of all patients present with metastasis at the time of diagnosis, and the 5-year overall survival rate across all stages is only 6%. Innovative in vivo research models are necessary to combat this cancer and to discover novel treatment strategies. The chorioallantoic membrane (CAM) model represents one 3D in vivo methodology that has been used in a large number of studies on different cancer types for over a century. This model is based on a membrane formed within fertilized chicken eggs that contain a dense network of blood vessels. Because of its high cost-efficiency, simplicity, and versatility, the CAM model appears to be a highly valuable research tool in the pursuit of gaining more in-depth insights into PDAC. A summary of the current literature on the usage of the CAM model for the investigation of PDAC was conducted and subdivided into angiogenesis, drug testing, modifications, personalized medicine, and further developments. On this comprehensive basis, further research should be conducted on PDAC in order to improve the abysmal prognosis of this malignant disease.
Activation of certain receptor tyrosine kinases (RTKs), such as FGFR, PDGFR, and VEGFR, has been implicated in tumor angiogenesis and progression of human cancers. In particular, bFGF and PDGF may promote cancer cell motility and tumor cell proliferation, whereas recruitment and proliferation of endothelial cells (ECs) and pericytes (vascular smooth muscle cells, VSMCs), two essential steps in angiogenesis, are mediated by activation of VEGFR and PDGFR. We therefore hypothesized that targeting the receptors to bFGF, PDGF and VEGF could prove valuable for therapy of pancreatic cancer, as these tyrosine kinases have been implicated in growth and angiogenesis of this aggressive cancer entity. Human pancreatic cancer cells, ECs and VSMCs were used for the experiments. Blockade of FGFR/PDGFR/VEGFR was achieved by using a novel small molecule tyrosine kinase inhibitor (TKI) (NVP-TKI258, Novartis Oncology). Effects of TKI on the proliferation of tumor cells, ECs and VSMCs were determined by MTT assays. Changes in motility of either cell type were determined in modified Boyden chambers. The inhibitory effects of FGFR/PDGFR/VEGFR inhibition in terms of phosphorylation of signaling intermediates were investigated by Western blotting. Changes in VEGF, survivin and DLL4 expression (as measures for endothelial survival function) were assessed by RT-PCR. Effects of NVP-TKI258 on tumor growth in vivo were investigated in a subcutaneous tumor model. Results showed that inhibition of multiple RTKs impaired growth of tumor cells, ECs and VSMCs in a dose-dependent manner in vitro . In addition, the bFGF- and FGF-7- induced tumor cell migratory properties were significantly diminished by NVP-TKI258 ( P P In vivo, NVP-TKI258 (30 mg/kg/daily) significantly reduced tumor growth rates ( P P Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 5578.
Mammalian target of rapamycin complex 2 (mTORC2) with its pivotal component rapamycin-insensitive companion of mTOR (RICTOR) is the major regulator of AKT phosphorylation and is increasingly implicated in tumor growth and progression. In cutaneous melanoma, an extremely aggressive and highly metastatic disease, RICTOR overexpression is involved in tumor development and invasiveness. Therefore, we investigated the impact of RICTOR inhibition in melanoma cells in vitro and in vivo with special emphasis on hepatic metastasis. Moreover, our study focused on the interaction of tumor cells and hepatic stellate cells (HSC) which play a crucial role in the hepatic microenvironment. In silico analysis revealed increased RICTOR expression in melanoma cells and tissues and indicated higher expression in advanced melanoma stages and metastases. In vitro, transient RICTOR knock-down via siRNA caused a significant reduction of tumor cell motility. Using a syngeneic murine splenic injection model, a significant decrease in liver metastasis burden was detected in vivo. Moreover, stimulation of melanoma cells with conditioned medium (CM) from activated HSC or hepatocyte growth factor (HGF) led to a significant induction of AKT phosphorylation and tumor cell motility. Blocking of RICTOR expression in cancer cells diminished constitutive and HGF-induced AKT phosphorylation as well as cell motility. Interestingly, RICTOR blockade also led to an abrogation of CM-induced effects on AKT phosphorylation and motility in melanoma cells. In conclusion, these results provide first evidence for a critical role of mTORC2/RICTOR in melanoma liver metastasis via cancer cell/HSC interactions.
Purpose of this study was to analyse the surgical management and long-term clinical outcome of patients diagnosed with colorectal liver metastases (CLM) over a period of 10 years using data from a German tumour registry.Retrospective analysis of 5772 patients diagnosed with colorectal adenocarcinoma between 2002 and 2007. Follow-up was continued until 2012.1426 patients (24.7%) had CLM; 1019 patients (71%) had synchronous, 407 patients (29%) developed metachronous CLM. Hepatic resection was performed in 374 of the 1426 CLM patients (26%). A significant increase in liver resection rate from 16.6% for the 2002 cohort to 32% in later cohorts was observed. In centers specialized in liver surgery, CLM resection rates reached 46.6%. However, up to 52% of patients diagnosed with three or less CLM did not undergo liver surgery, although, if resected, patients with 1 CLM show a similar long-time survival as CRC patients who do not develop any CLM. Univariate and multivariate analyses adjusted for age, sex, year of resection, time of CLM diagnosis and number of CLM revealed a significant survival benefit for CLM resection (HR =0.355; CI 0.305-0.414). Furthermore, significant impact on OS was seen for age at diagnosis, perioperative chemotherapy and number of CLM.We here present the first long-term, population-based analysis of the surgical management of CLM in Germany. Significant increase in hepatic resection rates, translating to a significant benefit in OS, was seen over years. However, we still see a striking potential for further improvements in interdisciplinary CLM management.
<b><i>Background:</i></b> Liver tumors that are extensive, multifocal, or critically located frequently require advanced techniques of liver resection including ‘functional augmentation' of liver segments. Here we describe the invention and stepwise establishment of a new technique - termed ‘in-situ split' liver resection or ‘ALPPS' - enabling liver resection in certain situations. <b><i>Methods:</i></b> The development of the technique in the first and the subsequent 8 patients in the index center, and also the method's spread throughout Germany and the world were reviewed. <b><i>Results:</i></b> In 2007, in the first patient, the new technique was developed intraoperatively by necessity. Due to the convincing outcome, it was deliberately applied again several months later in another patient, and thereafter (sparsely) used for liver resection for various indications. Following oral communication, the method spread throughout Germany, and later - mainly following the publication of the initial multicentric German series - very quickly disseminated worldwide. Currently, it is used for a very (if not overly) broad spectrum of indications by many hepatobiliary surgery centers. <b><i>Conclusion:</i></b> In-situ split/ALPPS is a newly developed technique for liver resection, which was established for very specific situations. This method has created a hype, and is currently used rather generously by many centers worldwide.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
