Neoplastic Stromal Cells Research Articles

New insights into the inflamed tumor immune microenvironment of gastric cancer with lymphoid stroma: from morphology and digital analysis to gene expression.

Gastric cancer with lymphoid stroma (GCLS) is characterized by prominent stromal infiltration of T-lymphocytes. The aim of this study was to investigate GCLS biology through analysis of clinicopathological features, EBV infection, microsatellite instability (MSI), immune gene-expression profiling and PD-L1 status in neoplastic cells and tumor immune microenvironment. Twenty-four GCLSs were analyzed by RNA in situ hybridization for EBV (EBER), PCR/fragment analysis for MSI, immunohistochemistry (PD-L1, cytokeratin, CD3, CD8), co-immunofluorescence (CK/PD-L1, CD68/PD-L1), NanoString gene-expression assay for immune-related genes and PD-L1 copy number alterations. CD3+ and CD8+ T-cell densities were calculated by digital analysis. Fifty-four non-GCLSs were used as control group. GCLSs displayed distinctive clinicopathological features, such as lower pTNM stage (p = 0.02) and better overall survival (p = 0.01). EBV+ or MSI-high phenotype was found in 66.7 and 16.7% cases, respectively. GCLSs harbored a cytotoxic T-cell-inflamed profile, particularly at the invasive front of tumors (p < 0.01) and in EBV+ cases (p = 0.01). EBV+ GCLSs, when compared to EBV- GCLSs, showed higher mRNA expression of genes related to Th1/cytotoxic and immunosuppressive biomarkers. PD-L1 protein expression, observed in neoplastic and immune stromal cells (33.3 and 91.7%, respectively), and PD-L1 amplification (18.8%) were restricted to EBV+/MSI-high tumors and correlated with high values of PD-L1 mRNA expression. This study shows that GCLS has a distinctive clinico-pathological and molecular profile. Furthermore, through an in-depth study of tumor immune microenvironment-by digital analysis and mRNA expression profiling-it highlights the role of EBV infection in promoting an inflamed tumor microenvironment, with putative therapeutic implications.

Effect of Intravenous Zoledronic Acid on Histopathology and Recurrence after Extended Curettage in Giant Cell Tumors of Bone: A Comparative Prospective Study.

Background:Giant cell tumor (GCT) of the bone is known for its locally aggressive behavior and tendency to recur. It is an admixture of rounded or spindle-shaped mononuclear neoplastic stromal cells and multinucleated osteoclast-like giant cells with their proportionate dispersion among the former. Zoledronic acid (a bisphosphonate) is being used in various cancers such as myelomas and metastasis, for osteoporosis with an aim to reduce the resorption of bone, and as an adjuvant treatment for the management of GCT of bone for reduction of local recurrence. We have carried out a prospective comparative study to assess the effect of intravenous infusion of zoledronic acid on histopathology and recurrence of GCT of bone.Materials and Methods:The study was carried out in the biopsy proven GCTs in 37 patients; 15 males and 22 females, in the age range from 17 to 55 years. They were treated with extended curettage. Of these 37 patients, 18 were given three doses of 4 mg zoledronic acid infusion at 3-week intervals and extended curettage was performed 2 weeks after the last infusion whereas the other 19 were treated with extended curettage without zoledronic infusion. The post infusion histopathology of the curetted material was compared with the histopathology of initial biopsy. All the patients were evaluated at 3-month intervals for the first 2 years and then six monthly thereafter, for local recurrence and functional outcome of limb using the Musculoskeletal Tumor Society (MSTS) score.Results:In postzoledronic infusion cases, the histopathology of samples showed abnormal stromal cells secreting matrix leading to fibrosis and calcification. The type of fibrosis and calcification was different from pathological calcification and fibrosis what is usually observed. There was a good marginalization and solidification of tumors which made surgical curettage easier in six cases in the study group. There was noticeable reduction in the number of giant cells and alteration in morphology of stromal cells to the fibroblastic-fibrocytic series type in comparison to preinfusion histopathology. Recurrence occurred in one case out of 18 patients in infusion group whereas in four cases among 19 patients in control group. The functional results were assessed, and the overall average MSTS score was 27.50 (range 24–30) and 27.00 (range 23.50–30) in the study and control groups, respectively.Conclusions:We observed that bisphosphonates reduce osteoclast activity and affects stromal cells in GCT, resulting in the reduction of their numbers and noticeable apoptosis. This results in better marginalization of the lesions and reduced recurrence. Extended curettage of friable GCT became easier and adequate which otherwise might not have been possible.

Diagnostic utility of histone H3.3 G34W, G34R, and G34V mutant-specific antibodies for giant cell tumors of bone

Giant cell tumors of bone (GCTBs) are characterized by mononuclear stromal cells and osteoclast-like giant cells; up to 95% have H3F3A gene mutation. The RANKL inhibitor denosumab, when used for the treatment of GCTB, leads to histological changes such as new bone formation and giant cell depletion. Here we assessed the diagnostic utility of immunohistochemical staining with the antibodies against histone H3.3 G34W, G34R and G34V mutant proteins for GCTB and other histologically similar bone and joint lesions. H3.3 G34W, G34R and G34V expressions were detected in mononuclear stromal cells in 47/51 (92%), 1/51 (2%) and 3/51 (6%) cases of primary GCTBs, respectively, in a mutually exclusive manner. All recurrent/metastatic GCTBs (n=14), post-denosumab GCTBs (n=8) and secondary malignant GCTBs (n=2) were positive for H3.3 G34W. The immunohistochemical results were essentially correlated with the H3F3A genotype determined by mutation analysis. In post-denosumab GCTBs, H3.3 G34W expression was seen in immature bone-forming cells. H3.3 G34W, G34R and G34V were negative in 121/122 cases of non-GCTB, including chondroblastoma, osteosarcoma, primary aneurysmal bone cyst and other giant cell-rich lesions. The exception was a single case of undifferentiated high-grade pleomorphic sarcoma that was positive for H3.3 G34W, suggesting the possibility of sarcomatous overgrowth of primary malignant GCTB. Therefore, H3.3 G34W/R/V mutant-specific antibodies are useful surrogate markers for the H3F3A genotype and helpful for the diagnosis of GCTB and its variants. The expression of H3.3 G34W mutant protein in post-denosumab GCTB suggests that neoplastic stromal cells may play a role in new bone formation.

The distinct clinical features of giant cell tumor of bone in pagetic and non-pagetic patients are associated with genetic, biochemical and histological differences.

Giant Cell Tumor of Bone (GCT) is a tumor characterized by neoplastic mesenchymal stromal cells and a high number of osteoclast-like multinucleated giant cells. Rarely, GCT could arise in bones affected by Paget's disease of bone (GCT/PDB). Although it is already known that GCT/PDB and GCT show a different clinical profile regarding the age-onset and skeletal localization, our deep clinical comparison between the two GCT/PDB and GCT cohorts, permitted us to identify additional differences (e.g. focality, ALP serum levels, the 5-year survival rate and the familial recurrence), strongly suggesting a different molecular basis. Accordingly, driver somatic mutations in H3F3A and IDH2 were described in GCT patients, while we recently identified a germline mutation in ZNF687 as the genetic defect of GCT/PDB patients.Here, we detected H3F3A mutations in our GCT cohort, confirming its molecular screening as the elected diagnostic tool, and then we excluded the two-hit in H3F3A and IDH2 as the trigger event for the GCT/PDB development. Importantly, we also identified an alternative biochemical profile with GCT/PDB not exhibiting the up-regulation of the GCT marker FGFR2IIIc. Finally, our histological analysis also showed a different appearance of the two forms of the tumor, with GCT/PDB showing a higher number of osteoclast-like giant cells (twice), with an abnormal number of nuclei per cell, corroborating its different behaviour in terms of neoplastic properties.We demonstrated that the distinct clinical features of pagetic and conventional GCT are associated with different genetic background, resulting in a specific biochemical and histological behaviour of the tumour.

Freezing Nitrogen Ethanol Composite May be a Viable Approach for Cryotherapy of Human Giant Cell Tumor of Bone.

Liquid nitrogen has been used as adjuvant cryotherapy for treating giant cell tumor (GCT) of bone. However, the liquid phase and ultrafreezing (-196°C) properties increase the risk of damage to the adjacent tissues and may lead to perioperative complications. A novel semisolid cryogen, freezing nitrogen ethanol composite, might mitigate these shortcomings because of less-extreme freezing. We therefore wished to evaluate freezing nitrogen ethanol composite as a coolant to determine its properties in tumor cryoablation. (1) Is freezing nitrogen ethanol composite-mediated freezing effective for tumor cryoablation in an ex vivo model, and if yes, is apoptosis involved in the tumor-killing mechanism? (2) Does freezing nitrogen ethanol composite treatment block neovascularization and neoplastic progression of the grafted GCTs and is it comparable to that of liquid nitrogen in an in vivo chicken model? (3) Can use of freezing nitrogen ethanol composite as an adjuvant to curettage result in successful short-term treatment, defined as absence of GCT recurrence at a minimum of 1year in a small proof-of-concept clinical series? The cryogenic effect on bone tissue mediated by freezing nitrogen ethanol composite and liquid nitrogen was verified by thermal measurement in a time-course manner. Cryoablation on human GCT tissue was examined ex vivo for effect on morphologic features (cell shrinkage) and DNA fragmentation (apoptosis). The presumed mechanism was investigated by molecular analysis of apoptosis regulatory proteins including caspases 3, 8, and 9 and Bax/Bcl-2. Chicken chorioallantoic membrane was used as an in vivo model to evaluate the effects of freezing nitrogen ethanol composite and liquid nitrogen treatment on GCT-derived neovascularization and tumor neoplasm. A small group of patients with GCT of bone was treated by curettage and adjuvant freezing nitrogen ethanol composite cryotherapy in a proof-of-concept study. Tumor recurrence and perioperative complications were evaluated at a minimum of 19months followup (mean, 24months; range, 19-30months). Freshly prepared freezing nitrogen ethanol composite froze to -136°C and achieved -122°C isotherm across a piece of 10±0.50-mm-thick bone with a freezing rate of -34°C per minute, a temperature expected to meet clinical tumor-killing requirements. Human GCT tissues revealed histologic changes including shrinkage in morphologic features of multinucleated giant cells in the liquid nitrogen (202±45μm; p=0.006) and freezing nitrogen ethanol composite groups (169±27.4μm; p<0.001), and a decreased nucleated area of neoplastic stromal cells for the 30-second treatment. Enhanced counts of terminal deoxynucleotidyl transferase dUTP nick end labeling(TUNEL)-positive cells verified the involvement of DNA fragmentation in cryoablated GCT tissues. Western blotting analysis on the expression of apoptosis regulatory proteins showed enhancement of proteocleavage-activated caspases 3, 8, and 9 and higher ratios of Bax/Bcl2 in the liquid nitrogen- and freezing nitrogen ethanol composite-treated samples. Numbers of blood vessels and human origin tumor cells also were decreased by freezing nitrogen ethanol composite and liquid nitrogen treatment in the GCT-grafted chicken chorioallantoic membrane model. Seven patients with GCT treated by curettage and adjuvant cryotherapy by use of freezing nitrogen ethanol composite preparation had no intra- or postoperative complications related to the freezing, and no recurrences during the study surveillance period. These preliminary in vitro and clinical findings suggest that freezing nitrogen ethanol composite may be an effective cryogen showing ex vivo and in vivo tumor cryoablation comparable to liquid nitrogen. The semisolid phase and proper thermal conduction might avoid some of the disadvantages of liquid nitrogen in cryotherapy, but a larger clinical study is needed to confirm these findings. Level IV, therapeutic study.

Crosstalk between stromal cells and cancer cells in pancreatic cancer: New insights into stromal biology

Pancreatic cancer (PC) remains one of the most lethal malignancies worldwide. Increasing evidence has confirmed the pivotal role of stromal components in the regulation of carcinogenesis, invasion, metastasis, and therapeutic resistance in PC. Interaction between neoplastic cells and stromal cells builds a specific microenvironment, which further modulates the malignant properties of cancer cells. Instead of being a “passive bystander”, stroma may play a role as a “partner in crime” in PC. However, the role of stromal components in PC is complex and requires further investigation. In this article, we review recent advances regarding the regulatory roles and mechanisms of stroma biology, especially the cellular components such as pancreatic stellate cells, macrophages, neutrophils, adipocytes, epithelial cells, pericytes, mast cells, and lymphocytes, in PC. Crosstalk between stromal cells and cancer cells is thoroughly investigated. We also review the prognostic value and molecular therapeutic targets of stroma in PC. This review may help us further understand the molecular mechanisms of stromal biology and its role in PC development and therapeutic resistance. Moreover, targeting stroma components may provide new therapeutic strategies for this stubborn disease.

Progressive Enrichment of Stemness Features and Tumor Stromal Alterations in Multistep Hepatocarcinogenesis.

Cancer stem cells (CSCs), a subset of tumor cells, contribute to an aggressive biological behavior, which is also affected by the tumor stroma. Despite the role of CSCs and the tumor stroma in hepatocellular carcinoma (HCC), features of stemness have not yet been studied in relation to tumor stromal alterations in multistep hepatocarcinogenesis. We investigated the expression status of stemness markers and tumor stromal changes in B viral carcinogenesis, which is the main etiology of HCC in Asia. Stemness features of tumoral hepatocytes (EpCAM, K19, Oct3/4, c-KIT, c-MET, and CD133), and tumor stromal cells expressing α-smooth muscle actin (α-SMA), CD68, CD163, and IL-6 were analyzed in 36 low grade dysplastic nodules (DNs), 48 high grade DNs, 30 early HCCs (eHCCs), and 51 progressed HCCs (pHCCs) by immunohistochemistry or real-time PCR. Stemness features (EpCAM and K19 in particular) were progressively acquired during hepatocarcinogenesis in combination with enrichment of stromal cells (CAFs, TAMs, IL-6+ cells). Stemness features were seen sporadically in DNs, more consistent in eHCCs, and peaked in pHCCs. Likewise, stromal cells were discernable in DNs, showed up as consistent cell densities in eHCCs and peaked in pHCCs. The stemness features and tumor stromal alterations also peaked in less differentiated or larger HCCs. In conclusion, progression of B viral multistep hepatocarcinogenesis is characterized by an enrichment of stemness features of neoplastic hepatocytes and a parallel alteration of the tumor stroma. The modulation of neoplastic hepatocytes and stromal cells was at low levels in precancerous lesions (DNs), consistently increased in incipient cancer (eHCCs) and peaked in pHCCs. Thus, in B viral hepatocarcinogenesis, interactions between CSCs and the tumor stroma, although starting early, seem to play a major role in tumor progression.

Genome-Wide Transcriptome Profiling of the Neoplastic Giant Cell Tumor of Bone Stromal Cells by RNA Sequencing.

Giant cell tumor of bone (GCTB) is the most common non-malignant primary bone tumor reported in Hong Kong. Failure of treatment in advanced GCTB with aggressive local recurrence remains a clinical challenge. In order to reveal the molecular mechanism underlying the pathogenesis of this tumor, we aimed to examine the transcriptome profiling of the neoplastic stromal cells of GCTB in this study. RNA-sequencing was performed on three GCTB stromal cell samples and one bone marrow-derived MSC sample and 174 differentially expressed genes (DEGs) were identified between these two cell types. The top five up-regulated genes are SPP1, F3, TSPAN12, MMP13, and LGALS3BP and further validated by qPCR and Western Blotting. Knockdown of SPP1 was found to induce RUNX2 and OPG expression in GCTB stromal cells but not the MSCs. Ingenuity pathway analysis (IPA) of the 174 DEGs revealed significant alternations in 23 pathways; variant calling analysis revealed 1915 somatic variants of 384 genes with high or moderate impacts. Interestingly, four canonical pathways were found overlapping in both analyses; from which VEGFA, CSF1, PLAUR, and F3 genes with somatic mutation were found up-regulated in GCTB stromal cells. The STRING diagram showed two main clusters of the DEGs; one cluster of histone genes that are down-regulated in GCTB samples and another related to osteoblast differentiation, angiogenesis, cell cycle progression, and tumor growth. The DEGs and somatic mutations found in our study warrant further investigation and validation, nevertheless, our study add new insights in the search for new therapeutic targets in treating GCTB. J. Cell. Biochem. 118: 1349-1360, 2017. © 2016 Wiley Periodicals, Inc.

Differentiation therapy of the neoplastic stromal cells in giant cell tumor of bone using the U.S. Food and Drug Administration (FDA)-approved drugs, rapamycin and simvastatin

Differentiation therapy of the neoplastic stromal cells in giant cell tumor of bone using the U.S. Food and Drug Administration (FDA)-approved drugs, rapamycin and simvastatin

Study of angiogenic signaling pathways in hemangioblastoma.

Hemangioblastoma (HB) is mainly located in the brain and the spinal cord. The tumor is composed of two major components, namely neoplastic stromal cells and abundant microvessels. Thus, hyper-vascularization is the hallmark of this tumor. Despite the identification of germline and/or epigenetic mutations of Von Hippel Lindau (VHL) gene as an important pathogenic mechanism of HB, little is known about the molecular signaling involved in this highly vascularized tumor. The present study investigated the key players of multiple angiogenic signaling pathways including VEGF/VEGFR2, EphB4/EphrinB2, SDF1α/CXCR4 and Notch/Dll4 pathways in surgical specimens of 22 HB. The expression of key angiogenic factors was detected by RT2 -PCR and Western blot. Immunofluorescent staining revealed the cellular localization of these proteins. We demonstrated a massive upregulation of mRNA levels of VEGF and VEGFR2, CXCR4 and SDF1α, EphB4 and EphrinB2, as well as the main components of Dll4-Notch signaling in HB. An increase in the protein expression of VEGF, CXCR4 and the core-components of Dll4-Notch signaling was associated with an activation of Akt and Erk1/2 and accompanied by an elevated expression of PCNA. Immuofluorescent staining revealed the expression of VEGF and CXCR4 in endothelial cells as well as in tumor cells. Dll4 protein was predominantly found in tumor cells, whereas EphB4 immunoreactivity was exclusively detected in endothelial cells. We conclude that multiple key angiogenic pathways were activated in HB, which may synergistically contribute to the abundant vascularization in this tumor. Identification of these aberrant pathways provides potential targets for a possible future application of anti-angiogenic therapy for this tumor, particularly when a total surgical resection becomes difficult due to the localization or multiplicity of the tumor.

Bortezomib Inhibits Giant Cell Tumor of Bone through Induction of Cell Apoptosis and Inhibition of Osteoclast Recruitment, Giant Cell Formation, and Bone Resorption.

Giant cell tumor of bone (GCTB) is a rare and highly osteolytic bone tumor that usually leads to an extensive bone lesion. The purpose of this study was to discover novel therapeutic targets and identify potential agents for treating GCTB. After screening the serum cytokine profiles in 52 GCTB patients and 10 normal individuals using the ELISA assay, we found that NF-κB signaling-related cytokines, including TNFα, MCP-1, IL1α, and IL17A, were significantly increased in GCTB patients. The results were confirmed by IHC that the expression and activity of p65 were significantly increased in GCTB patients. Moreover, all of the NF-κB inhibitors tested suppressed GCTB cell growth, and bortezomib (Velcade), a well-known proteasome inhibitor, was the most potent inhibitor in blocking GCTB cells growth. Our results showed that bortezomib not only induced GCTB neoplastic stromal cell (NSC) apoptosis, but also suppressed GCTB NSC-induced giant cell differentiation, formation, and resorption. Moreover, bortezomib specifically suppressed GCTB NSC-induced preosteoclast recruitment. Furthermore, bortezomib ameliorated GCTB cell-induced bone destruction in vivo As a result, bortezomib suppressed NF-κB-regulated gene expression in GCTB NSC apoptosis, monocyte migration, angiogenesis, and osteoclastogenesis. Particularly, the inhibitory effects of bortezomib were much better than zoledronic acid, a drug currently used in treating GCTB, in our in vitro experimental paradigms. Together, our results demonstrated that NF-κB signaling pathway is highly activated in GCTB, and bortezomib could suppress GCTB and osteolysis in vivo and in vitro, indicating that bortezomib is a potential agent in the treatment of GCTB. Mol Cancer Ther; 15(5); 854-65. ©2016 AACR.

A bladder cancer microenvironment simulation system based on a microfluidic co-culture model.

A tumor microenvironment may promote tumor metastasis and progression through the dynamic interplay between neoplastic cells and stromal cells. In this work, the most representative and significant stromal cells, fibroblasts, endothelial cells, and macrophages were used as vital component elements and combined with bladder cancer cells to construct a bladder cancer microenvironment simulation system. This is the first report to explore bladder cancer microenvironments based on 4 types of cells co-cultured simultaneously. This simulation system comprises perfusion equipment, matrigel channel units, a medium channel and four indirect contact culture chambers, allowing four types of cells to simultaneously interact through soluble biological factors and metabolites. With this system, bladder cancer cells (T24) with a tendency to form a 'reticular' structure under 3 dimensional culture conditions were observed in real time. The microenvironment characteristics of paracrine interactions and cell motility were successfully simulated in this system. The phenotype change process in stromal cells was successfully reproduced in this system by testing the macrophage effector molecule Arg-1. Arg-1 was highly expressed in the simulated tumor microenvironment group. To develop "precision medicine" in bladder cancer therapy, bladder cancer cells were treated with different clinical 'neo-adjuvant' chemotherapy schemes in this system, and their sensitivity differences were fully reflected. This work provides a preliminary foundation for neo-adjuvant chemotherapy in bladder cancer, a theoretical foundation for tumor microenvironment simulation and promotes individual therapy in bladder cancer patients.

APC haploinsufficiency coupled with p53 loss sufficiently induces mucinous cystic neoplasms and invasive pancreatic carcinoma in mice.

Adenomatous polyposis coli (APC), a tumor-suppressor gene critically involved in familial adenomatous polyposis, is integral in Wnt/β-catenin signaling and is implicated in the development of sporadic tumors of the distal gastrointestinal tract including pancreatic cancer (PC). Here we report for the first time that functional APC is required for the growth and maintenance of pancreatic islets and maturation. Subsequently, a non-Kras mutation-induced premalignancy mouse model was developed; in this model, APC haploinsufficiency coupled with p53 deletion resulted in the development of a distinct type of pancreatic premalignant precursors, mucinous cystic neoplasms (MCNs), exhibiting pathomechanisms identical to those observed in human MCNs, including accumulation of cystic fluid secreted by neoplastic and ovarian-like stromal cells, with 100% penetrance and the presence of hepatic and gastric metastases in >30% of the mice. The major clinical implications of this study suggest targeting the Wnt signaling pathway as a novel strategy for managing MCN.

Abstract 3163: Diet-induced obesity is associated with increased levels of IL-4 and IL-13, macrophage infiltration, fibrosis, and pancreatic neoplasia in the conditional KrasG12D mouse model

Abstract Background: Obesity is a well known risk factor for the development of several cancers including pancreatic cancer (PaCa). The formation of an inflammatory microenvironment with a complex communication between (pre)-neoplastic cells and stromal cells, including fibroblasts and inflammatory cells, is thought to promote tumor development during obesity. However, the exact molecular signals that are critical in this process are unknown. Recently, there has been interest in understanding the role of interleukins (IL)-4 and -13 in mediating the crosstalk between several cell types in cancer. E.g. they have been shown to promote the conversion of anti-tumorigenic M1 macrophages to pro-tumorigenic M2 macrophages. Aim: In this study we sought to investigate whether diet-induced obesity in the conditional KrasG12D mouse model of PaCa is associated with enhanced fibrosis and inflammation in the pancreas and to determine a possible role of IL-4 and -13. Methods and Results: Conditional KrasG12D mice and wildtype controls were fed a high fat, high calorie diet (HFCD) or control diet (CD) for 3 months. Mice fed the HFCD gained significantly more weight with a substantial enlargement of the visceral adipose tissue. Mutant mice fed the HFCD had more advanced pancreatic intraepithelial neoplasia lesions (PanINs). Compared to CD, mice fed the HFCD had a significant increase in pancreatic fibrosis (3.0±0.7 fold) and enhanced activation of pancreatic stellate cells (1.9±0.2) as assessed by immunohistochemical staining for fibronectin and α-smooth muscle actin, respectively. Flow cytometry demonstrated increased infiltration of Gr-CD11b+ macrophages (2.0±0.4 fold) into the pancreas in mice fed the HFCD. In addition, compared to the CD the HFCD was associated with increased tissue levels of IL-4 (43±5%) and IL-13 (65±20%) in the pancreas. Conclusion: Our results demonstrate that diet-induced obesity was associated with enhanced pancreatic neoplasia, inflammation, and fibrosis in the conditional KrasG12D mouse model. Our data further show that IL-4 and IL-13 are elevated in the pancreas of obese mice suggesting that these cytokines play a role, possibly in conversion of macrophages to the pro-tumorigenic M2 phenotype thereby promoting inflammation and tumor development. Citation Format: Chiara Birtolo, Guido Eibl, Aune Moro, Xiaoman Jung, Susan Morvaridi, Richard Waldron, Aurelia Lugea, Vay LW Go, Stephen J. Pandol. Diet-induced obesity is associated with increased levels of IL-4 and IL-13, macrophage infiltration, fibrosis, and pancreatic neoplasia in the conditional KrasG12D mouse model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3163. doi:10.1158/1538-7445.AM2015-3163

Denosumab for the treatment of giant cell tumor of the bone.

Giant cell tumor of bone is typically composed of neoplastic stromal cells and non-neoplastic osteoclastic giant cells. RANK-expressing osteoclastic giant cells are recruited by RANK ligand excreted by the stromal cells, and used by these neoplastic cells to create expansion space. Denosumab specifically binds to and inhibits RANK ligand, thereby eradicating osteoclastic giant cells from the tumor and thus reducing osteolytic activity. Clinical studies reported disease stabilization and clinical benefit in terms of reduced pain and analgesics use, avoided surgeries or surgeries with less morbid procedures. Adverse events observed in patients with giant cell tumor of bone were consistent with the known safety profile of denosumab with a very low incidence of hypocalcemia and osteonecrosis. Overall, denosumab was shown to suppress osteolytic activity and slow disease progression and is thus a treatment option for patients with giant cell tumor of bone.

Prognostic impact of reduced connexin43 expression and gap junction coupling of neoplastic stromal cells in giant cell tumor of bone.

Missense mutations of the GJA1 gene encoding the gap junction channel protein connexin43 (Cx43) cause bone malformations resulting in oculodentodigital dysplasia (ODDD), while GJA1 null and ODDD mutant mice develop osteopenia. In this study we investigated Cx43 expression and channel functions in giant cell tumor of bone (GCTB), a locally aggressive osteolytic lesion with uncertain progression. Cx43 protein levels assessed by immunohistochemistry were correlated with GCTB cell types, clinico-radiological stages and progression free survival in tissue microarrays of 89 primary and 34 recurrent GCTB cases. Cx43 expression, phosphorylation, subcellular distribution and gap junction coupling was also investigated and compared between cultured neoplastic GCTB stromal cells and bone marow stromal cells or HDFa fibroblasts as a control. In GCTB tissues, most Cx43 was produced by CD163 negative neoplastic stromal cells and less by CD163 positive reactive monocytes/macrophages or by giant cells. Significantly less Cx43 was detected in α-smooth muscle actin positive than α-smooth muscle actin negative stromal cells and in osteoclast-rich tumor nests than in the adjacent reactive stroma. Progressively reduced Cx43 production in GCTB was significantly linked to advanced clinico-radiological stages and worse progression free survival. In neoplastic GCTB stromal cell cultures most Cx43 protein was localized in the paranuclear-Golgi region, while it was concentrated in the cell membranes both in bone marrow stromal cells and HDFa fibroblasts. In Western blots, alkaline phosphatase sensitive bands, linked to serine residues (Ser369, Ser372 or Ser373) detected in control cells, were missing in GCTB stromal cells. Defective cell membrane localization of Cx43 channels was in line with the significantly reduced transfer of the 622 Da fluorescing calcein dye between GCTB stromal cells. Our results show that significant downregulation of Cx43 expression and gap junction coupling in neoplastic stromal cells are associated with the clinical progression and worse prognosis in GCTB.

Abstract B55: Molecular characterization of epithelial and stromal crosstalk associated with TRIM28 expression levels in colorectal cancer

Abstract Background: TRIM28 is a universal transcriptional co-repressor with pleotropic effects in both normal and tumor cells. We have previously shown that varying TRIM28 levels in epithelial cells and stromal fibroblasts have a prognostic value in colorectal cancer patients. The pathophysiological role of TRIM28 in carcinogenesis may therefore be associated with TRIM28 expression levels and cell type of expression within the tumor microenvironment. In this study we aim to dissect the molecular pathways associated with TRIM28 expression ratios within the tumor microenvironment by isolating individual populations of neoplastic epithelial and stromal cells and investigating their protein signaling networks. Methods: TRIM28 expression was analyzed by immunohistochemistry on FFPE tissue from 19 colorectal cancer patients. TRIM28 staining was evaluated in both epithelial and stromal compartments. IHC scoring of at least 2 units of difference in staining intensity between stromal fibroblasts and epithelial cells was defined as a high TRIM28 expression ratio and a low TRIM28 expression ratio was defined as 1 or 0 units of difference in staining intensity. Reverse-phase protein microarrays (RPMA) were constructed from laser capture micro-dissection (LCM) enriched tumor epithelium and stroma isolated from fresh-frozen tissue of the same patient cohort. The protein signaling networks were measured for 32 downstream signaling endpoints. Spearman rank analysis was used to assess the correlations between individual protein pairs. Correlation coefficient ρ ≥ 0.75 with P ≤ 0.01 was considered significant. Results: Immunohistochemical analysis of the FFPE tissue sections identified 10 TRIM28 high ratio cases and 9 TRIM28 low ratio cases. Proteomic networks were assessed in TRIM28 high and low ratio cases in fresh-frozen tissue using RPMA. Spearman ρ rank correlation analyses for the 32 signaling proteins revealed that 184 highly correlated protein pairs exclusive to the TRIM28 high ratio group, whereas 157 protein pairs were found exclusively in the TRIM28 low ratio group. In addition 191 protein pairs were shared across both TRIM28 high and low ratio groups. The caspases 3 and 7, as well as the cell surface receptor RAGE, were prominent in the high TRIM28 ratio group proteomic network, whereas the Metalloprotease MMP9 and the GTPase Ras-GRF1 were exclusive to the low TRIM28 ratio group. Furthermore we found Survivin and JNK to be prominent in the stromal compartment of the high TRIM28 cases. Conclusions: We characterized molecular pathways associated with TRIM28 expression ratios within the tumor microenvironment. Proteomic analysis revealed distinct protein signaling networks associated with varying TRIM28 expression levels in epithelial and stromal compartments. The study presents a novel way of deciphering molecular crosstalk between the epithelial and stromal compartments within the microenvironment. Citation Format: Seán Fitzgerald, Virginia Espina, Katherine M. Sheehan, Robert Cummins, Anthony O'Grady, Dermot Kenny, Richard O'Kennedy, Lance Liotta, Elaine W. Kay, Gregor Kijanka. Molecular characterization of epithelial and stromal crosstalk associated with TRIM28 expression levels in colorectal cancer. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr B55. doi:10.1158/1538-7445.CHTME14-B55

Enrichment of c-Met+ tumorigenic stromal cells of giant cell tumor of bone and targeting by cabozantinib

Giant cell tumor of bone (GCTB) is a very rare tumor entity, which is little examined owing to the lack of established cell lines and mouse models and the restriction of available primary cell lines. The stromal cells of GCTB have been made responsible for the aggressive growth and metastasis, emphasizing the presence of a cancer stem cell population. To identify and target such tumor-initiating cells, stromal cells were isolated from eight freshly resected GCTB tissues. Tumorigenic properties were examined by colony and spheroid formation, differentiation, migration, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, immunohistochemistry, antibody protein array, Alu in situ hybridization, FACS analysis and xenotransplantation into fertilized chicken eggs and mice. A sub-population of the neoplastic stromal cells formed spheroids and colonies, differentiated to osteoblasts, migrated to wounded regions and expressed the metastasis marker CXC-chemokine receptor type 4, indicating self-renewal, invasion and differentiation potential. Compared with adherent-growing cells, markers for pluripotency, stemness and cancer progression, including the CSC surface marker c-Met, were enhanced in spheroidal cells. This c-Met-enriched sub-population formed xenograft tumors in fertilized chicken eggs and mice. Cabozantinib, an inhibitor of c-Met in phase II trials, eliminated CSC features with a higher therapeutic effect than standard chemotherapy. This study identifies a c-Met+ tumorigenic sub-population within stromal GCTB cells and suggests the c-Met inhibitor cabozantinib as a new therapeutic option for targeted elimination of unresectable or recurrent GCTB.

A Translational Study of the Neoplastic Cells of Giant Cell Tumor of Bone Following Neoadjuvant Denosumab

Giant cell tumor of bone is a primary bone tumor that is treated surgically and is associated with high morbidity in many cases. This tumor consists of giant cells expressing RANK (receptor activator of nuclear factor-κB) and mesenchymal spindle-like stromal cells expressing RANKL (RANK ligand); the interaction of these cells leads to bone resorption. Denosumab is a monoclonal antibody that binds RANKL and directly inhibits osteoclastogenesis. Clinical studies have suggested clinical and histological improvement when denosumab was administered to patients with a giant cell tumor. However, no studies have yet examined the viability and functional characteristics of tumor cells following denosumab treatment. Specimens were obtained from six patients with a histologically confirmed giant cell tumor. Two of the patients had been treated with denosumab for six months. Primary cultures of stromal cells from fresh tumor tissue were established. Cell proliferation was measured over a two-day time course. The expression of RANKL and osteoprotegerin was analyzed with use of real-time PCR (polymerase chain reaction). Histological specimens from both patients who had completed denosumab treatment showed the absence of giant cells but persistence of stromal cells. Cell proliferation studies indicated that proliferation of stromal cells cultured from clinical specimens following denosumab treatment was approximately 50% slower than that of specimens from untreated patients. The expression of RANKL in the specimens from the treated patients was almost completely eliminated. Once the giant cell tumor tissue was no longer exposed to denosumab, the stromal cells continued to proliferate in vitro, albeit to a lesser degree. However, they also showed almost complete loss of RANKL expression. It is clear that treatment with denosumab only partially addresses the therapeutic need of patients with a giant cell tumor by wiping out the osteoclasts but leaving the neoplastic stromal cells proliferative.

Epigenetic silencing of genes and microRNAs within the imprinted Dlk1-Dio3 region at human chromosome 14.32 in giant cell tumor of bone.

BackgroundGrowing evidence exists that the neoplastic stromal cell population (GCTSC) within giant cell tumors (GCT) originates from mesenchymal stem cells (MSC). In a previous study we identified a microRNA signature that differentiates between these cell types. Five differentially expressed microRNAs are located within the Dlk1-Dio3 region on chromosome 14. Aberrant regulation within this region is known to influence cell growth, differentiation and the development of cancer. The aim of this study was to elucidate the involvement of deregulations within the Dlk1-Dio3 region in GCT pathogenesis.MethodsQuantitative gene and microRNA expression analyses were performed on GCTSCs and MSCs with or without treatment with epigenetic modifiers. Methylation analysis of differentially methylated regions was performed by bisulfite sequencing.ResultsIn addition to microRNA silencing we detected a significant downregulation of Dlk1, Meg3 and Meg8 in GCTSCs compared to MSCs. DNA methylation analyses of the Meg3-DMR and IG-DMR revealed a frequent hypermethylation within the IG-DMR in GCTs. Epigenetic modification could restore expression of some but not all analyzed genes and microRNAs suggesting further regulatory mechanisms.ConclusionEpigenetic silencing of genes and microRNAs within the Dlk1-Dio3 region is a common event in GCTSCs, in part mediated by hypermethylation within the IG-DMR. The identified genes, micro RNAs and microRNA target genes might be valuable targets for the development of improved strategies for GCT diagnosis and therapy.