Increased Lung Metastasis Research Articles

Role of C9orf140 in the promotion of colorectal cancer progression and mechanisms of its upregulation via activation of STAT5, β-catenin and EZH2

C9orf140 is a newly identified and characterized gene which is associated with cell proliferation and tumorigenicity. Expression of C9orf140 is upregulated in human gastric cancer and colorectal cancer (CRC); however, little is known about its role in CRC progression. We have investigated the clinical significance, biological effects and mechanisms of C9orf140 signaling. We found that the expression of C9orf140 is dramatically increased in a subset of CRC and correlates significantly with vascular invasion and lymph node metastasis. Our finding showed that knockdown of C9orf140 significantly reduced cell proliferation and invasion in vitro and dramatically increased overall survival and decreased lung metastasis in vivo. Conversely, overexpression of C9orf140 significantly increased lung metastasis and shortened overall survival when compared with control tumors. C9orf140-induced CRC cell invasion may depend on promoting the epithelial-mesenchymal transition progression. STAT5 may directly interact with the enhancer of zeste homolog 2 (EZH2) and β-catenin to enhance C9orf140 gene transactivation. Furthermore, C9orf140 may participate in cell invasion which is induced by STAT5, EZH2 or β-catenin activation. We describe the role of C9orf140 in CRC progression and find that C9orf140 overexpression may be regulated by STAT5, EZH2 and β-catenin interaction.

The Niacin/Butyrate Receptor GPR109A Suppresses Mammary Tumorigenesis by Inhibiting Cell Survival

GPR109A, a G-protein-coupled receptor, is activated by niacin and butyrate. Upon activation in colonocytes, GPR109A potentiates anti-inflammatory pathways, induces apoptosis, and protects against inflammation-induced colon cancer. In contrast, GPR109A activation in keratinocytes induces flushing by activation of Cox-2-dependent inflammatory signaling, and the receptor expression is upregulated in human epidermoid carcinoma. Thus, depending on the cellular context and tissue, GPR109A functions either as a tumor suppressor or a tumor promoter. However, the expression status and the functional implications of this receptor in the mammary epithelium are not known. Here, we show that GPR109A is expressed in normal mammary tissue and, irrespective of the hormone receptor status, its expression is silenced in human primary breast tumor tissues, breast cancer cell lines, and in tumor tissues of three different murine mammary tumor models. Functional expression of this receptor in human breast cancer cell lines decreases cyclic AMP production, induces apoptosis, and blocks colony formation and mammary tumor growth. Transcriptome analysis revealed that GPR109A activation inhibits genes, which are involved in cell survival and antiapoptotic signaling, in human breast cancer cells. In addition, deletion of Gpr109a in mice increased tumor incidence and triggered early onset of mammary tumorigenesis with increased lung metastasis in MMTV-Neu mouse model of spontaneous breast cancer. These findings suggest that GPR109A is a tumor suppressor in mammary gland and that pharmacologic induction of this gene in tumor tissues followed by its activation with agonists could be an effective therapeutic strategy to treat breast cancer.

Origins of Cancer Symposium Report

Origins of Cancer Symposium Report

Chemotherapy Counteracts Metastatic Dissemination Induced by Antiangiogenic Treatment in Mice

The development of resistance and progressive disease after treatment with angiogenesis inhibitors is becoming a controversial issue. We investigated the experimental conditions that cause multireceptor tyrosine kinase inhibitors (RTKI) to augment metastasis and whether opportune combinations with chemotherapy could counteract this effect. The renal Renca-luc tumor was transplanted orthotopically in the kidney of Balb/c mice, which then were or were not nephrectomized. The Lewis Lung carcinoma (LLC) was transplanted in the tibial muscle of C57/Bl6 mice. Treatment with the RTKI sunitinib started at different stages of tumor progression, mimicking neoadjuvant or adjuvant settings. Combination studies with paclitaxel, doxorubicin, cisplatin, gemcitabine, and topotecan were done on the LLC model, using opportune regimens. In a neoadjuvant setting, sunitinib inhibited Renca-luc tumor growth, prolonging survival despite an increase in lung metastasis; treatment after primary tumor surgery (adjuvant setting) or on established metastasis prolonged survival and decreased metastasis. Sunitinib increased lung metastasis from mice bearing early-stage LLC, but did not affect established metastases (no acceleration) from advanced tumors. Combinations with doxorubicin, topotecan, gemcitabine, but not cisplatin and paclitaxel, counteracted the increase in metastasis from LLC, partly reflecting their antitumor activity. Histology analysis after sunitinib confirmed tumor vascular changes and increased hypoxia. Topotecan at suboptimal daily doses reduced sunitinib-related metastasis, reducing tumor hypoxia. Tyrosine kinase inhibitors, as sunitinib, can have adverse malignant effects mainly in the neoadjuvant setting. The addition of chemotherapy might influence metastasis, depending on each drug mechanism of action and its regimen of administration.

Enhanced Cancer Metastasis in Mice Deficient in Vasohibin-1 Gene

Vasohibin-1 (VASH1) is isolated as an endogenous angiogenesis inhibitor produced by the vascular endothelium. We previously reported that tumor growth and tumor angiogenesis were augmented in VASH1 (−/−) mice. Here we examined whether VASH1 plays any role in cancer metastasis. When Lewis lung carcinoma (LLC) cells were inoculated in the footpad to observe spontaneous metastasis, a significant increase in lung metastasis together with inguinal lymph node metastasis was evident in the VASH1 (−/−) mice. Histological analyses revealed that vessels of the footpad tumor in VASH1 (−/−) mice were more immature, having fewer mural cells. However, when LLC cells were injected into a tail vein, the extent of lung metastasis was unchanged between wild-type mice and VASH1 (−/−) mice. When VASH1 in endothelial cells in culture was knocked-down by siRNA, we observed a decrease in the content of ZO-1, a component of tight junctions, which decrease resulted in increased transmigration of cancer cells across the endothelial cell monolayer. These results indicate that endogenous VASH1 tightens the endothelial barrier and makes tumor vessels resistant to cancer metastasis.

The Calcineurin-NFAT-Angiopoietin-2 Signaling Axis in Lung Endothelium Is Critical for the Establishment of Lung Metastases

The premetastatic niche is a predetermined site of metastases, awaiting the influx of tumor cells. However, the regulation of the angiogenic switch at these sites has not been examined. Here, we demonstrate that the calcineurin and nuclear factor of activated Tcells (NFAT) pathway is activated specifically in lung endothelium prior to the detection of tumor cells that preferentially metastasize to the lung. Upregulation of the calcineurin pathway via deletion of its endogenous inhibitor Dscr1 leads to a significant increase in lung metastases due to increased expression of a newly identified NFAT target, Angiopoietin-2 (ANG2). Increased VEGF levels specifically in the lung, and not other organ microenvironments, trigger a threshold of calcineurin-NFAT signaling that transactivates Ang2 in lung endothelium. Further, wedemonstrate that overexpression of DSCR1 or the ANG2 receptor, soluble TIE2, prevents the activationof lung endothelium, inhibiting lung metastases inour mouse models. Our studies provide insights into mechanisms underlying angiogenesis in the premetastatic niche and offer targets for lung metastases.

Annexin A2 depletion delays EGFR endocytic trafficking via cofilin activation and enhances EGFR signaling and metastasis formation

Enhanced epidermal growth factor receptor (EGFR) activity has been strongly linked to breast cancer progression and mediators of EGFR endocytosis may well be involved. We developed a semi-automated high-content fluorescence microscopy-based EGFR endocytosis screen to identify proteins that mediate EGFR endocytosis in human HBL100 breast cancer cells. Knockdown of 172 individual endocytosis and actin-regulatory genes with small interfering RNAs led to the identification of 14 genes of which the contribution to EGFR endocytosis in breast cancer is until now poorly defined, including DNAJC6, GDI2, FGD6, HAX1, NECAP2 and AnxA2. We show that depletion of the actin and endocytosis regulatory protein annexin A2 (AnxA2) in a panel of four triple negative breast cancer (TNBC) cell lines affected EGFR endocytosis. Depletion of AnxA2 in the aggressive and highly metastatic MDA-MB-231 TNBC cell line resulted in the inhibition of EGFR transport beyond the early endosomes. This inhibition coincided with enhanced epidermal growth factor (EGF)-induced cell migration and downstream signaling via c-Jun N-terminal kinase (JNK) and Akt. Moreover, AnxA2 knockdown increased lung metastasis formation in mice. The effect of AnxA2 knockdown on EGFR endocytosis in MDA-MB-231 was related to dephosphorylation/activation of the actin-severing protein cofilin, as re-expression of an inactive S3E-cofilin mutant, but not an active S3A-cofilin mutant, re-established EGFR endocytosis to control levels. Together, our data provide evidence for AnxA2 as a mediator of EGFR endocytosis and signaling in breast cancer via regulation of cofilin activation.

Cytochalasin D promotes pulmonary metastasis of B16 melanoma through expression of tissue factor

Cytochalasin D (CytD) targets actin, a ubiquitous protein in eukaryotic cells. Previous studies have focused mainly on the antitumor effects of CytD. We previously found CytD to promote lung metastasis in B16 melanoma cells, which we had not anticipated, and, therefore, in the present study we investigated the possible underlying mechanisms. B16 melanoma cells were co-cultured with CytD and other agents and used to establish a lung metastatic model. In this B16 melanoma metastatic model, significantly increased lung metastasis and lung weight were found in CytD-treated mice, which was almost completely suppressed by tissue factor (TF) RNA interference expressed via lentivirus. The results of northern and western blot, and real-time RT-PCR analysis showed that the expression of TF was significantly upregulated in B16 cells treated with CytD but was significantly inhibited by TF RNA interference. In addition, upregulation and phosphorylation of mitogen-activated protein kinase p38 were also found in the metastatic lung tissues treated with CytD and in the B16 cells co-cultured with CytD and factor VIIa (FVIIa), but not in cells cultured with CytD, dimethyl sulfoxide or FVIIa alone. These results indicate that CytD stimulates the expression of TF in B16 melanoma cells, activating both coagulation-dependent and -independent pathways via binding to FVIIa, eventually promoting lung metastasis. TF interference is a potential approach to the prevention of B16 melanoma metastasis.

Abstract 3123: The Notch pathway inhibits TGF-β signaling in breast cancer through HEYL-mediated crosstalk.

Abstract Acquired resistance to Transforming growth factor-β (TGF-β) is a key step in the early stages of tumorigenesis. Mutations of TGF-β signaling components, often found in other cancers, are rare in breast cancer, and little is known about the development of this resistance in breast cancer. On the other hand, activation of Notch pathway is known to play a substantial role in promoting breast cancer development. We hypothesized that crosstalk between these two pathways occurs through HEYL, a basic helix-loop-helix (bHLH) transcription factor, and a known direct target of Notch. We found that HEYL is overexpressed in 40% of breast cancers. Expression of Notch increased HEYL expression while knockdown of RBP-J, a critical mediator of Notch, reduced HEYL expression in HS578T and MDAMB-231 breast cancer cells. Taking into account the contradictory biological effects of Notch and TGF-β signaling, we sought to examine whether HEYL inhibits the TGF-β pathway. TGF-β treatment or Smad3 overexpression significantly increased the luciferase activity of the TGF-β responsive reporter vector, p3TP-Luc, and the P15 (CDKN2B) gene promoter, but this transactivation was strongly inhibited by HEYL. Bimolecular fluorescence complementation assays confirmed the interaction between Smad 3 and HEYL; immunoprecipitation assays with deletion constructs showed that the Basic domain of HEYL interacts with the MH2 domain of Smad3, and that their interaction is necessary for HEYL to inhibit TGF-β signaling. In addition, using a tet-off inducible breast cancer cell model, HEYL was shown to transcriptionally up-regulate many genes that drive metastasis and tumor angiogenesis. Supporting this concept, HEYL/HER2 double transgenic mice showed nearly 50% increase in lung metastasis (20% vs 46%) compared to HER2/neu mice. Similarly, lung colonization occurred in 100% of mice injected with MDAMB231 while HEYL-shRNAs reduced incidence to 50%. Therefore, HEYL promotes breast cancer growth and metastasis in Smad-dependent and Smad-independent mechanisms. Citation Format: Han Liangfeng, Adam Diehl, Nguyen K. Nguyen, Preethi Korangath, Teo Weiwen, Zhe Zhang, Scott Kominsky, Pedram Argani, Goran Landberg, Saraswati V. Sukumar. The Notch pathway inhibits TGF-β signaling in breast cancer through HEYL-mediated crosstalk. [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 3123. doi:10.1158/1538-7445.AM2013-3123

Abstract 1438: TNF-TNFR interactions influence tumor growth and metastasis by manipulating regulatory T cell homeostasis.

Abstract Tumor necrosis factor (TNF) signals via two cell surface receptors, TNFR1 and TNFR2 and is involved in a number of physiological processes including the regulation of immune cell homeostasis and function. Initially identified to cause tumor necrosis, a number of recent studies showed TNF to drive inflammation-induced cancer and metastasis. We employed two syngeneic in vivo bioluminescence imaging (BLI)-based mouse tumor models in conjunction with exogenous TNF treatment, TNF/TNFR knockout (ko) mice and bone marrow chimeras to determine the role of TNF-TNFR interactions in tumor growth and metastasis. 8-12 week-old female C57BL/6 mice were injected i.v. with luciferase-expressing B16F10 melanoma cells or orthotopically with luciferase-expressing Panc02 pancreatic cancer cells. We assessed the growth of B16F10 lung metastases and Panc02 primary pancreatic tumors using BLI. Finally, tumor-bearing organs were imaged ex vivo and analyzed by flow cytometry, immunofluorescence microscopy, and qRT-PCR. In the B16F10 model, treatment of mice with exogenous TNF markedly enhanced tumor metastasis resulting in elevated in vivo luciferase signals and increased lung metastases numbers. TNF-induced metastasis correlated with an accumulation of regulatory T cells (Tregs) in the lungs in vivo and we found TNF to induce Tregs in vitro in a TNFR2-dependent manner. This receptor was significantly higher expressed on Tregs than on effector CD4 T cells. The depletion of Tregs in genetically engineered mice attenuated B16 metastasis and ablated the pro-metastatic effect of TNF-treatment. Loss of either TNF or TNFR2 on immune cells in vivo reduced both metastasis and the number of Tregs. In the pancreatic tumor model, neither the loss of TNF nor TNFR2 changed tumor growth compared to wildtype mice. Loss of TNFR1 strongly promoted tumor growth and increased the infiltration of CD4 T cells and Tregs into the tumor tissue. Influx of CD8 T-cells into the tumors inversely correlated with the numbers of Tregs. Expression of activation markers on tumor infiltrating T cells was the same in TNFR1 ko and wildtype mice, as was mRNA-expression of immune suppressive genes. Loss of TNFR1 resulted in up-regulation of IL-4 expression within Panc02 tumors which suggests changes in TH1/TH2 immunity to be involved in tumor immunity in this model. Enhanced pancreatic tumor growth observed in TNFR1 ko mice may furthermore reflect reduced activity of other anti-tumoral acting cell types that are stimulated via TNFR1. We suggest that TNF activates TNFR2 on Tregs and thereby contributes to tumor-associated immune suppression in the B16F10 lung metastasis model. The induction of suppressive Tregs could be seen as a feedback-loop in which TNF down-regulates its own pro-inflammatory functions and eventually ablates immune control of tumors and enhances tumor growth and metastasis. Citation Format: Martin R. Chopra, Marlene Biehl, Carina A. Bäuerlein, Christian Brede, Ana-Laura Jordan Garotte, Sabrina Kraus, Simone S. Riedel, Katharina Mattenheimer, Miriam Ritz, Victoria Schäfer, Anja Mottok, Hermann Einsele, Harald Wajant, Andreas Beilhack. TNF-TNFR interactions influence tumor growth and metastasis by manipulating regulatory T cell homeostasis. [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 1438. doi:10.1158/1538-7445.AM2013-1438

Monocyte Chemoattractant Protein-1/CCL2 Produced by Stromal Cells Promotes Lung Metastasis of 4T1 Murine Breast Cancer Cells

MCP-1/CCL2 plays an important role in the initiation and progression of cancer. Since tumor cells produce MCP-1, they are considered to be the main source of this chemokine. Here, we examined whether MCP-1 produced by non-tumor cells affects the growth and lung metastasis of 4T1 breast cancer cells by transplanting them into the mammary pad of WT or MCP-1−/− mice. Primary tumors at the injected site grew similarly in both mice; however, lung metastases were markedly reduced in MCP-1−/− mice, with significantly longer mouse survival. High levels of MCP-1 mRNA were detected in tumors growing in WT, but not MCP-1−/− mice. Serum MCP-1 levels were increased in tumor-bearing WT, but not MCP-1−/− mice. Transplantation of MCP-1−/− bone marrow cells into WT mice did not alter the incidence of lung metastasis, whereas transplantation of WT bone marrow cells into MCP-1−/− mice increased lung metastasis. The primary tumors of MCP-1−/− mice consistently developed necrosis earlier than those of WT mice and showed decreased infiltration by macrophages and reduced angiogenesis. Interestingly, 4T1 cells that metastasized to the lung constitutively expressed elevated levels of MCP-1, and intravenous injection of 4T1 cells producing a high level of MCP-1 resulted in increased tumor foci in the lung of WT and MCP-1−/− mice. Thus, stromal cell-derived MCP-1 in the primary tumors promotes lung metastasis of 4T1 cells, but tumor cell-derived MCP-1 can also contribute once tumor cells enter the circulation. A greater understanding of the source and role of this chemokine may lead to novel strategies for cancer treatment.

Abstract A79: Elucidating the role of E2F2 transcription factor in mediating human breast cancer metastasis

Abstract In human breast cancer metastasis, it is not the primary tumor that is the cause of mortality but metastasis to distant sites. Therefore, it is important to elucidate the biological mechanism that underlies the metastatic processes. To address this, we utilized bioinformatic methods in combination with biochemical assays and genetic studies. Specifically, we crossed a MMTV-Myc mouse model with various activator E2Fs mutants and found that the tumor incidence decreased in the MMTV-Myc mice crossed with E2F2 and E2F3 mutant background. Surprisingly, we also found that the loss of E2F2 sharply increased lung metastasis in MMTV-Myc mice. Here, we test whether these observations in mice translate to human breast cancer and identify the genes under the control of E2F2 transcription factor that are responsible for mediating breast cancer metastasis. To achieve these aims, we examined the probability of activation of the E2F2 transcription factors in human breast cancer. We calculated the probability of E2F2 activation and used this data to stratify the human breast cancer samples and their associated metastatic clinical data. We performed hierarchical clustering of human and mouse gene expression datasets and uncovered two clusters of human breast tumors in which E2F2 played distinctly different roles in mediating metastasis. The human breast cancer samples that clustered with our mouse gene expression data exhibited the same role for E2F2 whereby it increased time to distant metastasis. We then examined genes that were differentially regulated within this cluster and found that there was a set of genes that were associated with a difference in human metastasis survival times and with the E2F2 knockout in the mouse model. To further explore the mechanism by which E2F2 mediates human breast cancer metastasis, we have identified four genes asputative E2F2 target genes including KLK1, MYH2, PTPRD and TNNC2. We found that partial knockdown of KLK1 promotes the migratory capacity of MCF7 cell in vitro. In addition, partial knockdown of PTPRD affected cellular morphology, where they were found to grow in discreet clusters while having little effect on the migration capacity in a scratch assay. We are currently exploring the effects of MYH2 and TNNC2 ablation on these cells. Taken together, we have begun to elucidate the roles of E2F2 transcription factor in mediating breast cancer metastasis as well as establishing a mechanism by which E2F2 regulates metastasis. Citation Format: Inez Yuwanita, Danielle Barnes, Eran Andrechek. Elucidating the role of E2F2 transcription factor in mediating human breast cancer metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr A79.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

P2-040 - Bevacizumab-Associated Hemoptysis in Colorectal Carcinoma with Multiple Lung Metastases: A Case Report

ABSTRACT A man in his 70s suffering from recurrent sigmoid colon cancer with multiple metastases was treated using tegafur/gimeracil/oteracil potassium/irinotecan (CPT-11) (16 cycles) as a first-line therapy, modified 5-FU/leucovorin/oxaliplatin as a second-line therapy and 5-FU/leucovorin/irinotecan (FOLFIRI)/bevacizumab as a third-line therapy. FOLFIRI and bevacizumab had to be discontinued after 47 cycles because of atypical pneumonia. Cetuximab/CPT-11 was used as a fourth-line regimen, but metastasis continued after two cycles. We used FOLFIRI–bevacizumab as a fifth-line therapy because a computed tomography (CT) scan did not show pneumonia, and his metastasis had been well controlled previously with this regimen. After 58 courses, CT scan showed no pneumonia, and there was no increase in lung metastases. On day 18 of 59 courses, he developed hemoptysis unexpectedly at his home, and he was brought to our hospital. On emergency CT scan, a cavity the lung field was detected in the lung field where lung metastasis had occurred, and Staphylococcus aureus was found in the patient's sputum. Intensive antibiotic therapy was initiated; however, the patient died three days later because of severe hemoptysis. Bevacizumab, a monoclonal antibody against a vascular endothelial growth factor, is used in several types of carcinoma, namely the lung, breast and colorectal cancers. In the phase trials of lung cancer, there were several reports of hemoptysis associated with bevacizumab, but there have been few reports on colorectal cancer. We reported a case of bevacizumab-associated hemoptysis in colorectal carcinoma with lung metastasis and reviewed the associated literature.

Regulation of DCIS to invasive breast cancer progression by Singleminded-2s (SIM2s)

Singleminded-2s (SIM2s) is a member of the bHLH/PAS family of transcription factors and a key regulator of mammary epithelial cell differentiation. SIM2s is highly expressed in mammary epithelial cells and down regulated in human breast cancer. Loss of Sim2s causes aberrant mouse mammary ductal development with features suggestive of malignant transformation, whereas over-expression of SIM2s promotes precocious alveolar differentiation in nulliparous mouse mammary glands, suggesting that SIM2s is required for establishing and enhancing mammary gland differentiation. To test the hypothesis that SIM2s regulates tumor cell differentiation, we analyzed SIM2s expression in human primary breast ductal carcinoma in situ (DCIS) samples and found that SIM2s is lost with progression from DCIS to invasive ductal cancer (IDC). Utilizing a MCF10DCIS.COM progression model, we have shown that SIM2s expression is decreased in MCF10DCIS.COM cells compared to MCF10A cells and reestablishment of SIM2s in MCF10DCIS.COM cells significantly inhibits growth and invasion in vitro and in vivo. Analysis of SIM2s-MCF10DCIS.com tumors showed that SIM2s promoted a more differentiated tumor phenotype including the expression of a broad range of luminal markers (CSN2 (β-casein), CDH1 (E-cadherin), and KER18 (keratin-18)) and suppressed genes associated with stem cell maintenance and a basal phenotype (SMO (smoothened), p63, SLUG (snail-2), KER14 (keratin-14) and VIM (vimentin)). Furthermore, loss of SIM2s expression in MCF10DCIS.COM xenografts resulted in a more invasive phenotype and increased lung metastasis likely due to an increase in hedgehog signaling and matrix metalloproteinase expression. Together, these exciting new data support a role for SIM2s in promoting human breast tumor differentiation and maintaining epithelial integrity.

Hepatic androgen receptor suppresses hepatocellular carcinoma metastasis through modulation of cell migration and anoikis

Early reports suggested androgen/androgen receptor (AR) signals promote hepatocarcinogenesis. However, all antiandrogen clinical trials failed in advanced hepatocellular carcinoma (HCC) without reasonable explanations. We examined AR functions in HCC cancer metastasis in this study. We examined hepatic AR roles in HCC metastasis by comparing liver hepatocyte AR knockout and wildtype in a carcinogen-induced HCC mouse model. We examined tumor histology, cancer metastatic risks, and cancer survival in vivo, as well as cell anoikis and migration using primary hepatic tumor culture in vitro. We also examined therapeutic potentials of AR expression combined with the molecular targeting agent sorafenib in an HCC metastasis mouse model. We found a novel cancer phenotype in which mice lacking hepatic AR developed more undifferentiated tumors and larger tumor size at the metastatic stage. These mice also died earlier with increased lung metastasis, suggesting that hepatic AR may play dual yet opposite roles to promote HCC initiation but suppress HCC metastasis. Mechanistic dissection found that hepatic AR could enhance anoikis and suppress migration of HCC cells by way of suppression of p38 phosphorylation/activation and the nuclear factor kappa B (NF-κB)/matrix metallopeptidase 9 (MMP9) pathway, respectively. In addition, the in vivo preclinical trials concluded that a combination therapy of increased AR expression and reduced multiple-kinase inhibitor (sorafenib) exhibited better therapeutic efficacy. Our study demonstrates that AR could orchestrate intrahepatic signaling hierarchies and cellular behaviors, consequently affect HCC progression. Results from combination therapy shed light on developing new therapeutic paradigms for battling HCC at later metastatic stages.

Failure of Rituximab in solid tumors is due to its inability to eliminate tumor evoked B regulatory cells (165.15)

Abstract We have previously shown that breast cancer generates regulatory B cells (tBregs) to convert Tregs and thereby to enable its metastasis. Thus, we decided to deplete tBregs using aCD20 antibody, a counterpart of the FDA approved strategy for the treatment of B cell malignancies (Rituximab). To our surprise, when tumor bearing mice were treated with αCD20 antibody, tumor progression was accelerated leading to increased lung metastasis. Thus, we hypothesized that tBregs may not be targeted by the antibody due to their low expression of CD20. Indeed, we found that B cell during their conversion to tBregs, downregulate their CD20 expression. Thus, tumor bearing mice treated with aCD20 antibody had enriched amounts of tBregs. We provide evidence that CD20 cannot be a target for the depletion of tBregs, explaining the failure of Rituximab to improve clinical outcomes in solid tumors. Instead, we developed an alternative strategy by in vivo targeting CpG through CXCR5 expressed by tBregs. We show that BLCArp-CpG inactivates tBregs, thereby reversing tumor metastasis. Taken together, suppressive B cells need to be controlled in solid tumors.

Abstract 4645: Preclinical development of RFF-1, a novel rational designed CXCL12 mimetic drug

Abstract The interaction between the chemokine receptor CXCR4 and its ligand, CXCL12, has been shown in pre-clinical models to facilitate tumour metastasis and to be involved in tissue repair and in recruitment of hematopoietic precursors. AMD3100, a potent CXCR4 antagonist, has been approved by FDA for stem cell mobilization in patients with multiple myeloma and non-Hodgkin lymphoma. Several other CXCR4 inhibitors are in clinical development (BTK140, CTCE-9908, MDX-1338 and POL6326), with the aim of inhibiting the development and progression of metastasis. In the rational design of CXCR4 inhibitors, a new class of cyclic peptide CXCL12-based CXCR4 inhibitors was discovered (IT Patent M12010A 000096; PCT WO2011/092575 A1) and validated for efficacy in in vitro and in vivo models. Among the tested peptides RFF-1 showed potent and specific inhibitory effects on CXCR4-mediated functions in multiple in vitro assays (P-ERK induction, migration and calcium mobilization CXCL12-induced and binding to CXCR4). C57/BL mice were injected with B16 melanoma cells transfected with human CXCR4. A 4,5 fold reduction in lung metastases was observed after 10 days treatment with 2 mg/kg intraperitoneally (i.p.) RFF-1 compared to the CXCR4 inhibitor AMD3100 (1.25mg/kg i.p), the powerful CXCR4 inhibitor not suitable for prolonged administration, that reduced lung metastases of about 4 fold. In another model of mouse osteosarcoma, K7M2 murine cells, were injected in Balb/C mice. A 3 fold reduction in lung metastases was observed after 15 days treatment with 10 mg/kg i.p. RFF-1 whereas AMD3100 treatment (2.5mg/kg i.p.) lead to 1.8 fold increase in lung metastases. Additionally, a 30% reduction in primary cell growth was achieved in a subcutaneous model of human renal cancer SN12C cells when i.p. treated with 2 mg/kg RFF-1. With the aim to evaluate RFF-1 efficacy in hematopoietic stem cell (HSC) mobilization DBA/2 healthy mice were injected with a single s.c. RFF-1 dose and peripheral blood HSC mobilization was evaluated by colony forming unit assay. Treatment with 30 mg/kg RFF-1 results in rapid, potent and durable mobilization of HSC reaching faster the peak compared to 20 mg/kg AMD3100. These results have prompted us to pursue the clinical development of peptide RFF-1. A first in human Phase I trial is planned to determine the maximal tolerated dose and recommended Phase 2 dose, toxicity profile, pharmacokinetics and antitumor activity of RFF-1 in patients with refractory solid tumors. The Phase I-II study of a novel CXCR4 antagonist provides the opportunity to develop settings in diseases where there is increasing evidence of a role for CXCR4 in the development and progression of metastases such as relapsed glioblastoma, neoadjuvant colorectal and breast cancer, and advanced prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4645. doi:1538-7445.AM2012-4645

Absence of the Basement Membrane Component Nidogen 2, but Not of Nidogen 1, Results in Increased Lung Metastasis in Mice

Nidogen 1 and 2 are ubiquitous basement membrane (BM) components. They show a divergent expression pattern in certain adult tissues with a prominent localization of nidogen 2 in blood vessel BMs. Deletion of either nidogen 1 or 2 in mice had no effect on BM formation, suggesting complementary functions. However, studies in these mice revealed isoform-specific functions with nidogen 1-deficient mice showing neurological abnormalities and wound-healing defects not seen in the absence of nidogen 2. To investigate this further nidogen 1- or 2-deficient mice were intravenously injected with B16 murine melanoma cells, and lung metastasis was analyzed. The authors could show that loss of nidogen 2, but not of nidogen 1, significantly promotes lung metastasis of melanoma cells. Histological and ultrastructural analysis of nidogen 1- and 2-deficient lungs did not reveal differences in morphology and ultrastructure of BMs, including vessel BMs. Furthermore, deposition and distribution of the major BM components were indistinguishable between the two mouse strains. Taken together, these results suggest that absence of nidogen 2 might result in subtle changes of endothelial BMs in the lung, which would allow faster passage of tumor cells through these BMs, leading to a higher metastasis rate and more larger tumors.

PD08-07: Wound-Healing Drainage Fluids Promote Triple Negative Breast Cancer Progression.

Abstract Triple negative breast cancers (TNBC) account for 15% of breast cancers. TNBCs carry a high risk of recurrence and deaths, due to the high rate of local and systemic relapse in these patients and no therapeutic options except chemotherapy are currently available. The TNBC pattern of recurrence present a distant recurrence peak at approximately 3 years and then declines rapidly thereafter, whereas in all non-TNBC types the recurrence risk seems to be constant over time. TNBC relapse risk is comparable to that of HER2−positive tumors subtype, in which growth-factors released during the healing process accelerate the early recurrences in HER2−positive patients. Thus, we speculate that also TNBC early relapse may depend on their capability to respond to wound-healing stimulation. To this aim, TNBC were treated with drainages to identify which receptors/pathways can be activated and play a driving role in TNBC progression. A pilot reverse phase protein microarray (RPMA) experiment on MDA-MB-231 TN cells drainage-fluids stimulated revealed a specific activation of PDGFR and VEGFR and their downstream pathways, whereas no significant changes were observed in other receptors, such as EGFR, IRS, Met and ERB3. The type of activated receptors suggested the involvement of endothelial receptors upon drainages stimulation and, indeed TNBC cell lines expressed endothelial molecules, such as CD34, CD31, CD146. Beside the proved role of some of these receptors in cellular proliferation, the TNBC endothelial-like phenotype prompt us to analyzed TNBC cell lines capability to form vascular-like channels when seeded on matrigel. Drainages were able to accelerate the formation of vascular channels in TNBC cell lines and, moreover to consistently increase proliferation of TNBC cells compared to non-TNBC cells. To prove whether receptors found activated by drainages play a key role in TNBC progression, we targeted PDGFR, VEGFR and other receptors possibly involved in angiogenesis and vasculogenic mimicry with sunitinib (targeting PDGFR, VEGFR, FGF and c-kit), anti-bFGF antibody (Ab)(targeting the ligand bFGF) and bevacizumab (targeting the VEGF) in TNBC cells drainage-stimulated in vitro. Sunitinib and anti-bFGF Ab halved the proliferation of TNBC cell lines and reduced of almost 60% the formation of vascular-like channels in TNBC cells, whereas bevacizumab modestly affect proliferation but not vasculogenic properties. Notably, sunitinib and anti-bFGF Ab strongly inhibited MDA-MB-231 and MDA-MB-468 xenografts tumor growth (sunitinib: 80%, and 70% Growth Index (GI), respectively; anti-bFGF Ab 70% and 60% GI, respectively) whereas bevacizumab determined no more than 30% decrease of tumor volume. Unfortunately, all these drugs did not efficiently control the development of lung metastases, that indeed significant increased compared to their control, possibly through induction of hypoxia processes. In conclusion, wound healing promotes TNBC progression by sustaining proliferation and vasculogenesis. The use of sunitinib and anti-bFGF antibody strongly inhibited tumor growth in mice models, but significantly increased lung metastases suggesting a combined use of these drugs with molecules able to interfere with hypoxia pathway. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD08-07.