bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2866: Functional impairment of microRNAs induced by chronic inflammation is the cause of inflammation-associated colon tumorigenesis.
Authors: Yoshikawa Takeshi
Published: August 2014

Background: A widespread downregulation of microRNAs is commonly observed in human cancers and is involved in cellular transformation and tumorigenesis. Because we previously reported that microRNA functions are inhibited under various kinds of cellular stresses including inflammatory cytokines in vitro, we hypothesized that chronic inflammation in vivo may also cause chronic functional impairment of microRNAs, which mimics a global reduction of microRNA abundance, resulting in a causal role in inflammation-associated tumorigenesis. Methods & Results: 1) To examine this hypothesis, we first confirmed the functional impairment of microRNAs under inflammatory stimuli in vitro using artificial reporter constructs. The derepression of microRNA-targeting reporter activities by inflammatory stimuli could also be observed using reporter constructs containing natural 3’UTR sequences of c-myc and Lin28B genes, which are targeted by endogenous let-7. 2) Next, we constructed reporter transgenic mice bearing CMV-promoter driven GFP construct carrying target sequences of microRNAs in its 3’UTR, and monitored the changes of microRNA functions in vivo during the course of a Dextran Sulfate Sodium (DSS) induced colitis-associated colon tumor model. The expression levels of GFP were significantly increased during colitis, suggesting that microRNA functions were impaired during the chronic inflammation in vivo. The expression levels of microRNA-target oncogenes such as c-myc and Lin28B in the colonic mucosa were indeed upregulated. 3) Lastly, to determine the consequences of the global functional impairment of microRNAs during the colitis, we examined Dicer-deficient mice, which have globally low levels of microRNA expression and may mimic the functional impairment of global microRNAs induced by chronic inflammation described above. As expected, Dicer deficient mice were more liable to have the colitis-associated tumors. This indicates that the global decrease of microRNAs leads to oncogenesis, suggesting that the functional impairment of global miRNAs during chronic inflammation can also be a cause of the inflammation-associated carcinogenesis. Conclusion: In conclusion, we propose a novel concept that the attenuation of global microRNA functions by chronic inflammation is the cause of inflammation-associated tumorigenesis.

Citation Format: Takeshi Yoshikawa. Functional impairment of microRNAs induced by chronic inflammation is the cause of inflammation-associated colon tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2866. doi:10.1158/1538-7445.AM2013-2866
Abstract 2871: Tumor-derived CCL2 promotes recruitment of CD11b/Gr1midmyeloid cells to sustain colorectal cancer liver metastasis.
Authors: Lim Su Yin , Zhao Lei , Gordon-Weeks Alex , Tapmeier Thomas , Muschel Ruth
Published: August 2014

Metastatic colorectal cancer (CRC) is one of the most prominent causes of cancer-related mortality. However, therapeutic options for patients with metastatic CRC are limited and development of new and more effective therapeutics aimed at downstaging the disease and prolonging survival is urgently required. Primary tumor dissemination to secondary sites, predominantly the liver, is a dynamic process dependent on the interactions between tumor cells and the host tissue microenvironment. Immune cells in the tumor microenvironment have been shown to play pivotal roles in the metastatic process but their pro-metastatic functions in CRC liver metastasis remains incompletely understood.

To simulate liver metastasis, MC38 colon carcinoma cells were injected into the spleen of C57BL/6 mice. A population of CD11b/Gr1mid cells, distinct from other metastasis-associated myeloid cells previously described, increased dramatically during establishment of liver metastases. Adoptive transfer of bone marrow cells confirmed that these CD11b/Gr1mid cells were derived from bone marrow progenitor cells. MC38 tumor cells expressed high levels of CCL2 and serum levels were elevated in tumor-bearing mice compared to controls. Inhibition of tumor-derived CCL2 using shRNA, and absence of its cognate receptor in CCR2 KO mice significantly diminished CD11b/Gr1mid cell infiltration into tumor-bearing livers. Importantly, inhibition of CD11b/Gr1mid cell recruitment led to a marked reduction in tumor burden. Moreover, when CD11b/Gr1mid cells were depleted in a transgenic CD11b-DTR mouse model, a striking decrease in tumor vessel density was observed, with a concomitant reduction in tumor cell proliferation.

Serum CCL2 concentrations were similarly elevated in CRC patients, including those who present metastasis, compared to normal controls. Furthermore, CD11b/CCR2 myeloid cells, analogous to the CD11b/Gr1mid population described in our mouse model, were identified in liver metastases of several CRC patients. Together, our studies demonstrate the importance of a distinct CD11b/Gr1mid myeloid subset in sustaining CRC liver metastasis and implicate a CCL2/CCR2-dependent pathway in their recruitment to metastatic sites. Our findings reinforce how tumor cells utilize host systems for successful propagation and identify a potential target for therapeutic manipulation.

Citation Format: Su Yin Lim, Lei Zhao, Alex Gordon-Weeks, Thomas Tapmeier, Ruth Muschel. Tumor-derived CCL2 promotes recruitment of CD11b/Gr1mid myeloid cells to sustain colorectal cancer liver metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2871. doi:10.1158/1538-7445.AM2013-2871
Abstract 2873: Epithelial NF-κB signaling is required for different functions in Kras- and EGFR-mediated lung tumorigenesis.
Authors: Ausborn Jamie A. , Sherrill Taylor , Zaynagetdinov Rinat , Polosukhin Vasiliy , McMahon Frank , Yull Fiona , Blackwell Timothy
Published: August 2014

The transcription factor nuclear factor-κB (NF-κB) is a key mediator of the inflammatory response, and its activation correlates with poor prognosis in non-small cell lung cancer patients. Oncogenic KRAS and epidermal growth factor receptor (EGFR) mutations occur frequently in lung adenocarcinoma and are associated with increased NF-κB activation in lung tumors. Recent papers have shown that inhibition of epithelial NF-κB signaling in a mouse model of Kras-mediated lung tumorigenesis decreases tumor formation. However, the mechanisms linking NF-κB signaling to tumor formation remain unclear. We hypothesize that epithelial NF-κB signaling is a common requirement for lung tumorigenesis. For our studies, we used mice that inducibly express oncogenic KrasG12D or EGFRL858R+T790M as well as a dominant negative inhibitor of κB signaling (DN-IκB) in Clara Cell Specific Protein (CCSP)-expressing lung epithelium (designated KrasDN or EGFRDN mice). EGFRDN mice developed smaller and fewer tumors after two months of doxycycline administration compared to mice expressing EGFRL858R+T790M alone, while KrasDN mice did not develop any tumors. In KrasDN mice, loss of Kras transgene expression and increased cell death were observed after one week of doxycycline, suggesting that NF-κB signaling may be required for survival of Kras mutant cells in vivo. In EGFRDN mice, NF-κB inhibition led to a significant reduction in the percentage of BAL neutrophils when compared to mice expressing EGFRL858R+T790M alone. In addition, NF-κB inhibition led to reduced expression of CXCR2 ligands CXCL1 and CXCL2, which are known NF-κB-regulated neutrophil chemoattractants. In vitro inhibition of CXCR2 did not affect proliferation of EGFR-mutant cells, suggesting that the critical function of CXCL1 and CXCL2 may be inflammatory cell recruitment/activation. Future studies will investigate the effects of CXCR2 inhibition and neutrophil depletion on EGFR-mediated tumor formation in vivo. Together, these results suggest that NF-κB signaling is required for both Kras- and EGFR-mediated lung tumorigenesis, but NF-κB's function in a tumor may depend on the driver mutation. From these studies, we hope to identify NF-κB-regulated genes critical for tumor formation as potential targets for the development of better therapeutic strategies for lung cancer patients.

Citation Format: Jamie A. Ausborn, Taylor Sherrill, Rinat Zaynagetdinov, Vasiliy Polosukhin, Frank McMahon, Fiona Yull, Timothy Blackwell. Epithelial NF-κB signaling is required for different functions in Kras- and EGFR-mediated lung tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2873. doi:10.1158/1538-7445.AM2013-2873
Abstract 2906: Towards breast cancer drug repurposing based on a pathway modeling approach.
Authors: Ibrahim Sara
Published: August 2014

Molecular connectivity maps between drugs and proteins in specific disease contexts, especially breast cancer, can be particularly valuable, offering an opportunity to gain global perspectives on both the therapeutic and toxicological profiles of drugs. To assess drug pharmacological effects, we assume that “ideal” drugs for a patient can treat or prevent disease by modulating gene expression profiles of the patient to the similar level with those in healthy people. Starting from this hypothesis, we build comprehensive disease-gene-drug connectivity relationships with drug-protein directionality (inhibit/activate) information based on a computational connectivity maps (CMaps) platform. In this work, we develop a novel approach based on integrative pathway modeling using breast cancer as a case study. We identify and rank breast cancer related drugs/compounds with their overall drug-protein “connectivity map” profile. First, we retrieve breast cancer associated proteins through the CMaps platform by using breast cancer as a query term. Second, we retrieve breast cancer related pathways by using breast cancer associated proteins as input and searching in the Human Pathway Database (HPD), PAGED, and the PubMed. Third, we integrate the breast cancer related pathways into unified pathway models, from which we categorize the pharmaceutical effects of candidate drugs on all breast cancer associated proteins as either “therapeutic” or “toxic”. Expression values are given to all relevant proteins on the pathway. Potential drugs and targets are retrieved from C-Map, DrugBank, and MetaDrug. Finally, we transform the integrated pathway into network models and rank drugs based on the network topological features of drug targets, drug-affecting genes/proteins, and curated disease-associated proteins. The case studies correlated very well with the known pharmacological profiles of cancer drugs, highlighting the significance of the platform that we developed. Ongoing research can potentially change future drug discovery practices.

Citation Format: Sara Ibrahim. Towards breast cancer drug repurposing based on a pathway modeling approach. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2906. doi:10.1158/1538-7445.AM2013-2906
Abstract 2937: Dual roles of ERK2 to TRAIL sensitivity in SK-N-MC neuroepithelioma cells.
Authors: Jung Hye Lim , Lee Myoung Woo , Eom Ji Eun , Kim Dea Seong , Park Hyo-Jung , Yu Dong-Kyung , Son Meong Hi , Lee Soo Hyun , Yoo Keon Hee , Sung Ki Woong , Koo Hong Hoe
Published: August 2014

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a new promising agent for clinical use since it kills a wide range of tumor cells but not normal cells. It is regulated by 2 death receptors (DR), DR4 (TRAIL-R1) and DR5 (TRAIL-R2), and 2 decoy receptors (DcR), DcR1 (TRAIL-R3) and DcR2 (TRAIL-R4). However, the determining factors of the sensitivity to TRAIL cytotoxicity are not clearly understood. This study aims to elucidate the role of extracellular signal-regulated kinase (ERK) on enhancement of TRAIL cytotoxicity in cultured neuroepithelioma cell line SK-N-MC. When 1 μg/ml cisplatin-pretreated cells were exposed to 100 ng/ml TRAIL for 48 h, apoptotic cell death increased, compared with the cells treated with cisplatin or TRAIL alone (66% versus 27% or 9% apoptotic cell death). In addition, pretreatment with cisplatin in SK-N-MC cells significantly increased ERK1/2 activity and increased expression levels of DR5, but not DR4, DcR1 and DcR2, which correlated with increase of their susceptibility to TRAIL cytotoxicity. Introduction of ERK2 siRNA or ERK2 shRNA in SK-N-MC cells significantly decreased cisplatin-induced DR5 expression, suggesting that cisplatin-induced ERK2 activity is involved in DR5 expression. On the other hand, treatment with 20 μM U0126, an inhibitor of MEK, completely reduced basal ERK1/2 activity and induced cell death in SK-N-MC cells. In addition, pretreatment with U0126 increased TRAIL-mediated apoptosis via up-regulation of DR5 expression in response to the decrease in basal ERK2 activity. Because pretreatment with U0126 completely inhibited not only cisplatin-induced ERK2 activation but also basal ERK2 activity, the following treatment with TRAIL significantly increased cell death, indicating that constitutively activated ERK2 blocks DR5 expression in SK-N-MC cells. Taken together, our results implicate that basal ERK2 activity is involved in TRAIL resistance but induced ERK2 plays a role in TRAIL sensitivity, and suggest that the enhanced sensitivity of SK-N-MC cells to TRAIL is associated with an increase in DR5 expression.

Citation Format: Hye Lim Jung, Myoung Woo Lee, Ji Eun Eom, Dea Seong Kim, Hyo-Jung Park, Dong-Kyung Yu, Meong Hi Son, Soo Hyun Lee, Keon Hee Yoo, Ki Woong Sung, Hong Hoe Koo. Dual roles of ERK2 to TRAIL sensitivity in SK-N-MC neuroepithelioma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2937. doi:10.1158/1538-7445.AM2013-2937
Abstract 2954: Novel interaction between FLIP/DAPK: role for RON in androgen-independent prostate cancer.
Authors: Batth Izhar S. , Gong Jingjing , Kumar A. Pratap
Published: August 2014

Patients with Hormone refractory metastatic prostate cancer (HRPCA) have a 5-year survival of less than 30%. Therefore, it is imperative that new therapeutic strategies targeting advanced stage prostate cancer (PCA) be developed. 2-Methoxyestradio (2-ME2) is an endogenously produced compound that has been shown to successfully treat PCA. As part of our efforts in understanding its mechanism of action, we discovered that the tyrosine kinase RON (Recepteur ‘Origine Nantais) was a target for inhibition. RON Kinase has been previously shown to be upregulated in murine PCA. RON has also been reported to mediate cell migration, and invasion in various cancers. However, the precise role of RON signaling in prostate carcinogenesis is unclear. Our data revealed that RON is upregulated in HRPCA cell lines and human prostate tumors. Using genetic approaches we found novel, causal association between RON and FLICE-like inhibitory protein, also known as FLIP (a known target of 2-ME2), and an increase in Death Associated Protein Kinase (DAPK1). Interestingly, RON overexpression in early stage PCA cell lines induced the transcriptional activation of the Androgen Receptor (AR) and FLIP. Stimulation of RON with its ligand MSP (macrophage stimulating protein) also yielded heightened promoter activity of AR and its downstream target genes including PSA and FLIP. Functionally, these responses translated to increased cell migration in RON overexpressing cells and loss of this migratory potential with RON silencing. Interestingly, 2-ME2 treatment also reduced the migration of HRPCA cells. Migration in wild-type HRPCA cells is also sensitive to regulation with 2-ME2 treatment. Overall these data suggests that RON kinase is a major player in promoting advanced-stage prostate cancer in part due to its ability to regulate apoptosis through novel FLIP/DAPK1 interaction. Supported by NIH (CA 135451, APK).

Citation Format: Izhar S. Batth, Jingjing Gong, A. Pratap Kumar. Novel interaction between FLIP/DAPK: role for RON in androgen-independent prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2954. doi:10.1158/1538-7445.AM2013-2954
Abstract 2956: c-FLIP (L) dual function in cervical cancer.
Authors: Ili Carmen G. , Brebi Priscilla , Andana Alejandra , Garcia Patricia , Leal Pamela , Tapia Oscar , Viscarra Tamara , Weber Helga , Roa Juan
Published: August 2014

Cellular FLICE-like inhibitory protein (c-FLIP) is a caspasa-8/10 homolog catalytically inactive that interferes with the efficient formation of DISC. There are three isoforms of this protein: c-FLIPL (long) of 55kDa, c-FLIPS (short) of 26kDa y c-FLIPR (Raji) of 24kDa. c-FLIPS and c-FLIPR functions have been well established: both can block extrinsic pathway of apoptosis by inhibiting procaspasa-8 activation in DISC. However, c-FLIPL function still remains unclear. When c-FLIPL is overexpressed, as in some cancers, has an anti-apoptotic function very similar to c-FLIPS, but also can be a proapoptotic molecule at low concentrations. The aim of this study is to characterize c-FLIP functions in cervical uterine carcinogenesis.

Three cervical cancer cell lines were used in this study: SiHa, C-4I and C-33A. c-FLIP expression in cell lines was determined by real time PCR and western blottting. c-FLIP expression was transiently downregulated by siRNA and the silencing effects on cell viability, proliferation and apoptosis were analysed, by comparing with a control negative siRNA-transfected cells.

Using MTS analysis, SiHa and C4I c-FLIP transfected cells showed a increment of viability compared with scramble, since 24 hours after transfection in C 4I and 72 hours in SiHa (P<0.05), while C-33A cells do not show differences. Ki-67 immunocitochemestry was performed to evaluate proliferation in cervical cell lines. Statistical differences were found between SiHa and C 4I c-FLIP transfected cells compared with scramble (P<0.05). All three c-FLIP transfected cell lines showed a higher level of apoptosis than scramble control (P<0.05), using a TUNEL-based analyzed performed by flow cytometry.

Our results suggest that c-FLIPL could be having a dual function in cervical cancer cell lines, both inhibiting proliferation and apoptosis.

Grant Support: This investigation was financed by Proyect CORFO-INNOVA N°07CN13PBT-222 and Proyect CORFO N° 09CN14-5960 (CEGIN). CI is recipient of grants from FONDECYT Postdoctoral Proyect N° 3130630. PB is recipient of grants from FONDECYT Postdoctoral Proyect N° 3120141

Citation Format: Carmen G. Ili, Priscilla Brebi, Alejandra Andana, Patricia Garcia, Pamela Leal, Oscar Tapia, Tamara Viscarra, Helga Weber, Juan Roa. c-FLIP (L) dual function in cervical cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2956. doi:10.1158/1538-7445.AM2013-2956

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.
Abstract 2958: Knockdown of Src expression dissolves resistance to TRAIL-induced apoptosis in oral cancer cells.
Authors: Hamakawa Tomohiro , Hino Satoshi , Nakashiro Koh-ichi , Hamakawa Hiroyuki
Published: August 2014

A radical operation for advanced oral cancer results in malfunction of chewing, swallowing, and pronouncing etc. Nevertheless, the most standard therapy for oral cancer is a surgical resection because of its good outcome compared to radiation and chemotherapy. It is expected that treatment is less-invasive and effective against not only primary lesion but also metastatic sites or cells with metastatic potential. Because the acquisition of resistance to anoikis and apoptosis is considered as an essential event to successfully metastasize, we focused on the apoptotic signaling pathways mediated by natural death ligands. In this study, we have used oral squamous cell carcinoma (OSCC) cell lines with distinct metastatic potential and attempted to disclose their apoptosis sensitivity. More than half of the cells died under the low attachment culture condition in all OSCC cell lines with no relation between their metastatic potential, while other kind of cancer cell lines showed anoikis resistance. SAS cells established from human tongue squamous cell carcinoma showed modest sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), whereas SAS-T5 and SAS-L1 cells, a clone with high metastatic potential showed robust resistance. Fas ligand (Anti-Fas/CD95 monoclonal antibody) showed the similar trend of apoptosis induction as well as TRAIL, but TNF-α had no effect in these cells. We confirmed that the expression levels and the localization of TRAIL receptors were not correlated with TRAIL sensitivity. One of the mechanisms underlying the differences in resistance between these cell lines was an activity of Src kinase. Phosphorylated Src (Tyr 416), the active form, was upregulated in SAS-T5 and SAS-L1 cells compared to parental SAS cells. Src inhibitor PP2 suppressed cell proliferation in response to dependence on Src signaling. Downregulation of Src with siRNA made metastatic cells dissolve the resistance to TRAIL-induced apoptosis. These results suggest that combination therapy with TRAIL plus medicine inhibiting Src kinase may be a treatment strategy for oral squamous cell carcinoma.

Citation Format: Tomohiro Hamakawa, Satoshi Hino, Koh-ichi Nakashiro, Hiroyuki Hamakawa. Knockdown of Src expression dissolves resistance to TRAIL-induced apoptosis in oral cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2958. doi:10.1158/1538-7445.AM2013-2958
Abstract 2972: Pharmacological reactivation of epigenetically regulated genes in prostate cancer.
Authors: Krause Hans , Ikromov Odiljon , Al Kamal Imad , Magheli Ahmed , Kempkensteffen Carsten , Miller Kurt
Published: August 2014

Transcriptional silencing caused by promoter hypermethylation is a widespread mechanism for inactivation of known and putative tumor suppressor genes in many types of cancers. GSTP1, CDKN2A, CDH1, APC, and RASSF1A among others are known to be downregulated in prostate cancer. The aim of this study was to search for hitherto unknown genes that are upregulated after treatment by demethylating agents (i.e. DMNT inhibitors) thereby marking them as potential new therapeutic targets and putative biomarkers in prostate carcinogenesis.

Prostate cancer cell lines DU-145 and LNCaP were treated in three independent biological experiments with 100μM zebularine for ten days and monitored for cytotoxic and apoptotic side effects. Efficacy of the treatment was verified on the RNA expression level of known epigenetically regulated genes. Expression changes of total RNA from treated and untreated cells were compared using whole genome expression microarrays (Affymetrix Human Gene 1.0 ST). A number of conspicuously upregulated genes (>15.0-fold, presence of CpG islands, higher expression in normal prostate) were further evaluated by Q-PCR in 50 cases of paired normal and tumor tissue samples of prostate cancer patients who underwent radical prostatectomy in our clinic between 2002 and 2004.

The seryl-tRNA synthetase gene SARS was discovered by us for the first time to be downregulated in 34/50 cases (66%; p = 0,04) in prostate cancer. The DNA-damage-inducible transcript 1 (DDIT1), also known as GADD45A and was downregulated in 42/50 cases (84%; p = 0,0004). The discovery of a downregulated GADD45A in our independent experiments supports the already known fact of a methylation-mediated repression of GADD45A in prostate cancer (Ramachandran et al., 2009) and its suitability as a potential therapeutic target. In addition, we found a statistically significant inverse correlation of SARS expression and raising patient Gleason scores.

Based on our estimated “upregulation-rate” of the promoter hypermethylation gold standard gene for prostate cancer GSTP1 in 98% of our patient samples (48/50; p = 0,0001) we present a robust workflow for the discovery of methylation-mediated transcriptionally inactivated genes.

Citation Format: Hans Krause, Odiljon Ikromov, Imad Al Kamal, Ahmed Magheli, Carsten Kempkensteffen, Kurt Miller. Pharmacological reactivation of epigenetically regulated genes in prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2972. doi:10.1158/1538-7445.AM2013-2972
Abstract 2999: Targeted depletion of all somatically mutated genes in lung cancer cells facilitates identification of mutationally activated novel drivers of lung cancer.
Authors: Fawdar Shameem , Trotter Eleanor W. , Li Yaoyong , Ientile Sara , Miller Crispin , Brognard John
Published: August 2014

Approximately 70% of all NSCLC patients present with late stage disease (stage III-IV) and there is a pressing need to develop better therapies for these patients. This remains a major challenge as the underlying genetic causes of nearly half of all NSCLCs remain unknown. Recent success with therapies targeting mutationally activated EGFR and constitutively active EML4-ALK serve as proof of principle that drugs targeting genetically activated drivers of lung cancer result in better, more durable therapeutic responses in patients. In an effort to identify novel mutationally activated drivers of lung cancer, we performed a targeted siRNA screen to knockdown all somatically mutated genes in a panel of six NSCLC cell lines. Using this approach we have identified three mutationally activated drivers that include MLK1, PAK7 and FGFR4. We demonstrate that mutations in these genes are activating, that the cancer cells that harbour the genetically activated oncogenes rely on these drivers to maintain cell proliferation and survival and inhibition of these activated kinases results in specific killing of the lung cancer cells. As cancer genomic data accumulates at an unprecedented rate, approaches must be developed to filter through this data to identify druggable drivers that could lead to better therapeutic options for patients in the clinic. Our studies demonstrate that combining targeted siRNA screens with cancer genomics will be a successful approach to identify novel drivers of cancer.

Citation Format: Shameem Fawdar, Eleanor W. Trotter, Yaoyong Li, Sara Ientile, Crispin Miller, John Brognard. Targeted depletion of all somatically mutated genes in lung cancer cells facilitates identification of mutationally activated novel drivers of lung cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2999. doi:10.1158/1538-7445.AM2013-2999
Abstract 301: Microenvironmental regulation of epithelial-mesenchymal transitions in breast cancer metastasis.
Authors: Gao Dingcheng , Fisher Kari , Choi Hyejin , Dannenberg Andrew J. , Vahdat Linda , Altorki Nasser , Mittal Vivek
Published: August 2014

Metastatic spread is the main cause of death in breast cancer patients. To successfully develop metastatic lesions, tumor cells exhibit plasticity to adapt to the changing microenvironment that they encounter at both the primary and distant sites. Notably, tumor cells undergo epithelial-mesenchymal transition (EMT) to acquire metastatic potential. In the metastatic organ, the disseminated tumor cells are thought to undergo mesenchymal to epithelial transition (MET) to form lethal macrometastatic lesions. However, while EMT/MET has been well demonstrated in cancer cell lines in vitro, whether such transitions occur in vivo is debated.

Our study is based on an emerging paradigm that microenvironmental regulation of epithelial-mesenchymal transitions contributes to tumor growth and metastasis. To evaluate this, we have devised a lineage tracing approach where a unique EMT-induced Cre-mediated fluorescence switch system monitors epithhelial-mesenchymal transitions in physiologically relevant orthotopic and spontaneous breast cancer metastasis in vivo. Using this system, we found that the CD11b+F4/80+ tumor-associated macrophages promote EMT in the primary tumor by secreting TGFβ1 and PDGFA, while the CD11b+Gr1+ myeloid progenitors facilitate MET of disseminated tumor cells in metastatic lungs by secreting proteoglycan versican thereby providing novel mechanistic insights into how the tumor-stroma cross talk confers prometastatic properties.

Our finding that different subsets of inflammatory cells are associated with EMT in the primary tumor and MET in the metastatic organ has provided clinical translation opportunities. Previously, the therapeutic targeting of EMT (i.e. TGFβ1 blockade) has been associated with the caveat that it may actually promote the formation of fatal macrometastases. Here, the identification of unique cellular EMT and MET regulators provides an opportunity for inhibiting one process without promoting the other, or inhibiting both EMT and MET simultaneously. Importantly, administration of non-steroidal anti-inflammatory drugs impaired metastases by targeting specific inflammatory populations that contribute to the EMT/MET-promoting microenvironment in preclinical mouse models of breast cancer.

Citation Format: Dingcheng Gao, Kari Fisher, Hyejin Choi, Andrew J. Dannenberg, Linda Vahdat, Nasser Altorki, Vivek Mittal. Microenvironmental regulation of epithelial-mesenchymal transitions in breast cancer metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 301. doi:10.1158/1538-7445.AM2013-301
Abstract 3015: Identification of a novel gene target involved in tumor growth and metastasis of non-small cell lung cancer.
Authors: Chen Honglin , Lee James , Kljavin Noelyn M. , Johnson Leisa , Liang Yuxin
Published: August 2014

We have discovered a potential oncogenic role of a gene in non-small cell lung cancer (NSCLC) using RNAi technology. Silencing of the gene significantly inhibits soft agar colony formation of NSCLC cell lines, whereas its inhibition on cell proliferation in liquid culture is modest. This effect was observed in multiple murine and human NSCLC cell lines with varied Kras and p53 status. The inhibition on soft agar colony formation is reversed with ectopic overexpression of a cDNA encoding the full-length gene. Knocking down the expression of the gene also significantly impairs migration and enhances detachment-induced anoikis of NSCLC cells. An investigation of the molecular mechanisms reveals that silencing of the gene cytoskeleton signaling network. In xenograft studies using stable luciferase-expressing inducible shRNA cell lines, silencing of the gene upon doxycycline treatment leads to a modest reduction in tumor volumes while significantly decreases bioluminescent signals at metastatic sites including lung and lymph nodes. Furthermore, gene expression analyses in KrasG12D/p53 deletion-driven mouse tumors and clinical tumor samples show significantly increased expression of the gene in lung cancer as well as multiple other cancer types. Taken together, we have uncovered a novel oncogenic function of a gene in NSCLC, which could provide a potential new therapeutic target for cancer intervention.

Citation Format: Honglin Chen, James Lee, Noelyn M. Kljavin, Leisa Johnson, Yuxin Liang. Identification of a novel gene target involved in tumor growth and metastasis of non-small cell lung cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3015. doi:10.1158/1538-7445.AM2013-3015

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.
Abstract 3016: Implication of delta-catenin-promoted E-cadherin processing on human prostate cancer progression.
Authors: Kim Hangun , Yoon Somy , Park So-Yeon , Hwang Jun Eul , Kim Kwonseop , Kim Kyung Keun
Published: August 2014

Although δ-catenin overexpression is frequently observed in some human cancers, the mechanistic implications of δ-catenin expression in epithelial cells and carcinomas remain elusive. In this study, we found that prostate cancer cells overexpressing δ-catenin show an increase in multi-layer growth in culture. In these cells, δ-catenin colocalizes with E-cadherin at the plasma membrane, and the E-cadherin processing is noticeably elevated. A deletion mutant of δ-catenin totally abolishes the δ-catenin-induced E-cadherin processing and the multi-layer growth of the cells. In addition, prostate cancer cells overexpressing δ-catenin display an elevated total β-catenin level and increase nuclear distribution, resulting in the activation of β-catenin/LEF-1-mediated transcription. Indeed, human prostate tumor xenograft in nude mice, which is derived from cells overexpressing δ-catenin, shows increased β-catenin nuclear localization and more rapid growth rates. Moreover, the metastatic xenograft tumor weights positively correlate with the level of 29 kD E-cadherin fragment, and primary human prostate tumor tissues also show elevated levels of δ-catenin expression and the E-cadherin processing. Taken together, these results suggest that δ-catenin plays an important role in prostate cancer progression through inducing E-cadherin processing and thereby activating β-catenin-mediated oncogenic signals.

Citation Format: Hangun Kim, Somy Yoon, So-Yeon Park, Jun Eul Hwang, Kwonseop Kim, Kyung Keun Kim. Implication of delta-catenin-promoted E-cadherin processing on human prostate cancer progression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3016. doi:10.1158/1538-7445.AM2013-3016

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.
Abstract 3036: The dependence receptor TrkC is a putative colon cancer tumor suppressor.
Authors: Genevois Anne-Laure , Ichim Gabriel , Coissieux Marie-May , Lambert Marie-Pierre , Lepinasse Florian , Herceg Zdenko , Scoazec Jean-Yves , Tauszig-Delamasure Servane , Mehlen Patrick
Published: August 2014

Backgrounds & Aims: The TrkC neurotrophin receptor belongs to the functional dependence receptors family, members of which share the ability to induce apoptosis in the absence of their ligands. Such a trait has been hypothesized to confer tumor-suppressor activity. Indeed, cells that express these receptors are thought to be dependent on ligand availability for their survival, a mechanism that inhibits uncontrolled tumor cell proliferation and migration. TrkC is yet a relatively classic tyrosine kinase receptor and therefore generally rather considered as a proto-oncogene. We investigated here whether, because of its dependence receptor activity, TrkC is a putative tumor suppressor in colorectal malignancies.

Methods: The level of TrkC was analyzed in a panel of 45 primary sporadic colorectal carcinomas. Loss of heterozygosity and epigenetic alterations in the TrkC promoter were also analyzed. The level of TrkC was also analyzed in a panel of colorectal cancer cell lines. The TrkC tumor suppressive activity was investigated by expressing TrkC and related TrkC variants in colorectal cancer cell lines and by measuring apoptosis, anchorage-independent growth, migration and tumor growth in a chicken model.

Results: We show here that TrkC expression is down-regulated in a large fraction of human colorectal cancers, mainly through promoter methylation. Moreover, we show that TrkC silencing by promoter methylation is a selective advantage for colorectal cell lines to limit tumor cell death. Consequently, we show that reestablished TrkC expression in colorectal cancer cell lines is associated with tumor cell death and inhibition of in vitro characteristics of cell transformation and in vivo tumor growth.

Conclusions: The loss of TrkC expression observed in human colorectal cancer is a selective advantage for tumor cell survival. Thus, TrkC appears to be a putative new colon cancer tumor suppressor.

Citation Format: Anne-Laure Genevois, Gabriel Ichim, Marie-May Coissieux, Marie-Pierre Lambert, Florian Lepinasse, Zdenko Herceg, Jean-Yves Scoazec, Servane Tauszig-Delamasure, Patrick Mehlen. The dependence receptor TrkC is a putative colon cancer tumor suppressor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3036. doi:10.1158/1538-7445.AM2013-3036
Abstract 3043: Akt-mTorc2 signaling underlies cellular addiction to HER3 signaling in HER2-amplified cancers.
Authors: Amin Dhara N. , Ahuja Deepika , Ducker Gregory S. , Yaswen Paul , Shokat Kevan , Moasser Mark
Published: August 2014

HER2 amplified breast cancers are characterized by constitutive HER3 phosphorylation. Efforts to target the functionally relevant HER2-HER3 signaling complex in these tumor cells has proven difficult due to robust feedback signaling mechanisms that restore its signaling in the face of anything short of the complete inactivation of HER2 kinase activity. To study this in more depth, we used a combination of genetic and chemical genetic approaches designed to study the cellular adaptational responses to network perturbation. We find that positive or negative perturbation of any signaling node from upstream HER2 or HER3 down to the two mTor complexes results in compensatory responses that function to maintain homeostasis. The responses to various perturbations are mechanistically distinct, but taken together reveal an uncompromising core topology driven by a concentric Akt-mTorc2 positive-feedback loop buffered by HER3 and PHLPP nodes. While mTorc1 signaling is also subject to feedback regulation, it is not involved in the core topology and its output is not always protected in these tumors. The central role of mTor is consistent with its known functions as a master regulator of cellular homeostasis highly conserved across eukaryotes. But the inclusion of HER3 in this central homeostatic network is a tumor cell anomaly. To better delineate how this homeostatic network is altered in tumor cells, we compared and contrasted the network topology in a panel of HER2-amplified cancer cells with a panel of immortalized breast epithelial cells. Much of the feedback circuitries are preserved across tumor and untransformed cells. But the driving Akt-mTorc2 positive-feedback loop is lacking in untransformed cells. This is due to the fact that Akt drives mTorc2 signaling in tumor cells but not in untransformed cells. Consistent with a central role of mTorc2 in these tumors, knockdown of Rictor, but not Raptor, is lethal in HER2-amplified SkBr3 tumor cells. These studies reveal a key alteration of Akt-mTor signaling in HER2 driven tumors that underlies the pathological incorporation of HER3 into an mTor-driven network, thus putting the HER2-HER3 tumor driver under the protection of this evolutionarily ancient pathway, highly competent at homeostasis.

Citation Format: Dhara N. Amin, Deepika Ahuja, Gregory S. Ducker, Paul Yaswen, Kevan Shokat, Mark Moasser. Akt-mTorc2 signaling underlies cellular addiction to HER3 signaling in HER2-amplified cancers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3043. doi:10.1158/1538-7445.AM2013-3043
Abstract 3057: miR-211 is contributive to the progression of oral carcinoma through modulating transcription factor 12 (Tcf12).
Authors: Chen Yi-Fen , Lin Shu-Chun , Chang Kuo-Wei
Published: August 2014

Oral squamous cell carcinoma (OSCC) is one of the prevalent neoplasms worldwide. MicroRNAs (miRNAs) are short RNA molecules that regulate pathogenesis, including OSCC carcinogenesis, by post-transcriptional down-regulation of target genes. Our previous study has identified a relationship between high miR-211 expression and the invasiveness of OSCC. This study further dissects the molecular mechanisms underlying the progression of OSCC as affected by miR-211. miR-211 is predicted to target the 3’UTR of transcription factor 12 (Tcf12). Reporter assays confirmed the direct targeting of miR-211 on Tcf12. Tcf12 is a helix-loop-helix transcription factor with obscure functions in malignancies. miR-211 expression decreased both endogenous and exogenous Tcf12. Exogenous Tcf12 expression suppressed oncogenic phenotypes of OECM-1 OSCC cells. On the contrary, knockdown of endogenous Tcf12 expression enhanced the oncogenic phenotypes of OSCC cells. Tcf12 expression was highly associated with EZH2 activity, and the expression levels of HOX family members in OSCC cells. To elucidate the in vivo oncogenic roles of miR-211 in OSCC carcinogenesis, K14 promoter driven miR-211 transgenic mouse lines (K14-GFP- miR-211) were established. The increased miR-211 expression was found to be associated with Tcf12 down-regulation in the squamous epithelium of transgenic mice. After tumor induction by 4-nitroquinoline 1-oxide, the transgenic mice exhibited more and bigger tumors comparing to wild type mice. The incidence of epithelial dysplasia on the tongue was also higher in the transgenic mice than that in control mice. In summary, this study reveals that miR-211 is a regulator of OSCC progression by targeting Tcf12. The in vivo model based on the K14-GFP-miR-211 transgenic mice will help further studies of the pathogenic mechanisms underlying OSCC progression and development of therapeutic strategy.

Citation Format: Yi-Fen Chen, Shu-Chun Lin, Kuo-Wei Chang. miR-211 is contributive to the progression of oral carcinoma through modulating transcription factor 12 (Tcf12). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3057. doi:10.1158/1538-7445.AM2013-3057
Abstract 3058: miRNA networks mediate the tumor suppressive function of FOXO proteins.
Authors: Nadler Monica , Zabolian Robin , Ndebele Kenneth , bertomeu thierry , Bucur Octavian , Pennarun Bodvael , Khosravi-Far Roya
Published: August 2014

FOXO transcription factors, as regulators of a variety of cellular functions, including promotion of apoptotic cell death, are negatively regulated by various oncogenic signaling cascades and have emerged as bona fide tumor suppressors. Indeed, studies by others and us have shown that the suppression of FOXO function is critical in promoting evasion of apoptosis and is a significant occurrence in several hematological malignancies. Consequently, FOXO proteins signify an important therapeutic target in hematopoietic malignancies as well as other types of cancer, where repression of FOXO plays a key role in malignancy. Since transcription factors are not yet easily “druggable," it is vital to identify mediators of FOXO function that can be readily targeted. It is now apparent that aberrant miRNA expression plays a major role in cell and tissue-specific manner in the pathogenesis of various types of cancers including hematological malignancies. Both miRNA loss of function and miRNA overexpression have been shown to target key cellular proteins and contribute to cancer pathogenesis. Conversely, miRNA genes themselves have been shown to be direct targets of transcription factors that are known as important tumor suppressors or oncogenic proteins. Through a systematic screening approach, we have identified members of three miRNA clusters that are dependent on FOXO transcription factors for expression. We have observed that the level of these miRNAs is dependent on BCR-ABL status of hematopoeitc cells and they their levels are changed in specimens from Leukemia patients. Our studies indicates a mechanism of action for FOXO tumor suppressors whereby members of two miRNA families are direct transcriptional targets of FOXO3. Moreover, these miRNAs target and reduce the expression of two key oncogenic factors, the serine/threonine kinase mTOR, and proto-onocogene c-myc, to keep cell growth at bay and prevent tumorigenesis. Our investigations have unraveled the miRNA arm of the FOXO tumor suppression network.

Citation Format: Monica Nadler, Robin Zabolian, Kenneth Ndebele, thierry bertomeu, Octavian Bucur, Bodvael Pennarun, Roya Khosravi-Far. miRNA networks mediate the tumor suppressive function of FOXO proteins. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3058. doi:10.1158/1538-7445.AM2013-3058

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.