TLR2 and TLR9 Blockade Using Specific Intrabodies Inhibits Inflammation-Mediated Pancreatic Cancer Cell Growth

Pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC) remains a deadly cancer worldwide with a need for new therapeutic approaches. A dysregulation in the equilibrium between pro- and anti-inflammatory responses with a predominant immunosuppressive inflammatory reaction in advanced stage tumors seem to contribute to tumor growth and metastasis. The current therapies do not include strategies against pro-tumorigenic inflammation in cancer patients. We have shown that the upregulated cell surface expression of Toll-like Receptor (TLR) 2 and of TLR9 inside PDAC cells maintain chronic inflammatory responses, support chemotherapeutic resistance, and mediate tumor progression in human pancreatic cancer. We further demonstrated intracellular TLR2 and TLR9 targeting using specific intrabodies, which resulted in downregulated inflammatory signaling. In this study, we tested, for the first time, an intrabody-mediated TLR blockade in human TLR2- and TLR9-expressing pancreatic cancer cells for its effects on inflammatory signaling-mediated tumor growth. Newly designed anti-TLR2- and anti-TLR9-specific intrabodies inhibited PDAC growth. Co-expression analysis of the intrabodies and corresponding human TLRs showed efficient retention and accumulation of both intrabodies within the endoplasmic reticulum (ER), while co-immunoprecipitation studies indicated both intrabodies interacting with their cognate TLR antigen within the pancreatic cancer cells. Cancer cells with attenuated proliferation expressing accumulated TLR2 and TRL9 intrabodies demonstrated reduced STAT3 phosphorylation signaling, while apoptotic markers Caspases 3 and 8 were upregulated. To conclude, our results demonstrate the TLR2 and TLR9-specific intrabody-mediated signaling pathway inhibition of autoregulatory inflammation inside cancer cells and their proliferation, resulting in the suppression of pancreatic tumor cell growth. These findings underscore the potential of specific intrabody-mediated TLR inhibition in the ER relevant for tumor growth inhibition and open up a new therapeutic intervention strategy for the treatment of pancreatic cancer.

Assessing the conversion of electronic medical record data into antibiotic stewardship indicators

BACKGROUND

Measuring the appropriateness of antibiotic use is crucial for antibiotic stewardship (ABS) programmes to identify targets for interventions.

OBJECTIVES

To assess the technical feasibility of converting electronic medical record (EMR) data into ABS indicators.

METHODS

In this observational feasibility study covering a period of 2 years, the EMRs of patients hospitalized at a large non-university hospital network and receiving at least one dose of a systemic antibiotic were included. ABS indicators measuring steps in the process of antibiotic prescription proposed by the literature were collected and rephrased or defined more specifically to be calculable if needed. Algorithms were programmed in R to convert EMR data into ABS indicators. The indicators were visualized in an interactive dashboard and the plausibility of each output value was assessed.

RESULTS

In total, data from 25 337 hospitalizations from 20 723 individual patients were analysed and visualized in an interactive dashboard. Algorithms could be programmed to compute 89% (25/28) of all pre-selected indicators assessing treatment decisions automatically out of EMR data, with good data quality for 46% (13/28) of these indicators. According to the data quality observed, the most important issues were (i) missing or meaningless information on indication (e.g. 'mild infection') and (ii) data processing issues such as insufficiently categorized metadata.

CONCLUSIONS

The calculation of indicators assessing treatment decisions from EMRs was feasible. However, better data structure and processing within EMR systems are crucial for improving the validity of the results.

Platelet-derived growth factor (PDGF) cross-signaling via non-corresponding receptors indicates bypassed signaling in colorectal cancer

Platelet-derived growth factor (PDGF) signaling, besides other growth factor-mediated signaling pathways like vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF), seems to play a crucial role in tumor development and progression. We have recently provided evidence for upregulation of PDGF expression in UICC stage I-IV primary colorectal cancer (CRC) and demonstrated PDGF-mediated induction of PI3K/Akt/mTOR signaling in CRC cell lines. The present study sought to follow up on our previous findings and explore the alternative receptor cross-binding potential of PDGF in CRC. Our analysis of primary human colon tumor samples demonstrated upregulation of the PDGFRβ, VEGFR1, and VEGFR2 genes in UICC stage I-III tumors. Immunohistological analysis revealed co-expression of PDGF and its putative cross-binding partners, VEGFR2 and EGFR. We then analyzed several CRC cell lines for PDGFRα, PDGFRβ, VEGFR1, and VEGFR2 protein expression and found these receptors to be variably expressed amongst the investigated cell lines. Interestingly, whereas Caco-2 and SW480 cells showed expression of all analyzed receptors, HT29 cells expressed only VEGFR1 and VEGFR2. However, stimulation of HT29 cells with PDGF resulted in upregulation of VEGFR1 and VEGFR2 expression despite the absence of PDGFR expression and mimicked the effect of VEGF stimulation. Moreover, PDGF recovered HT29 cell proliferation under simultaneous treatment with a VEGFR or EGFR inhibitor. Our results provide some of the first evidence for PDGF cross-signaling through alternative receptors in colorectal cancer and support anti-PDGF therapy as a combination strategy alongside VEGF and EGF targeting even in tumors lacking PDGFR expression.

Translational development of ABCB5+ dermal mesenchymal stem cells for therapeutic induction of angiogenesis in non-healing diabetic foot ulcers

Background

While rapid healing of diabetic foot ulcers (DFUs) is highly desirable to avoid infections, amputations and life-threatening complications, DFUs often respond poorly to standard treatment. GMP-manufactured skin-derived ABCB5⁺ mesenchymal stem cells (MSCs) might provide a new adjunctive DFU treatment, based on their remarkable skin wound homing and engraftment potential, their ability to adaptively respond to inflammatory signals, and their wound healing-promoting efficacy in mouse wound models and human chronic venous ulcers.

Methods

The angiogenic potential of ABCB5⁺ MSCs was characterized with respect to angiogenic factor expression at the mRNA and protein level, in vitro endothelial trans-differentiation and tube formation potential, and perfusion-restoring capacity in a mouse hindlimb ischemia model. Finally, the efficacy and safety of ABCB5⁺ MSCs for topical adjunctive treatment of chronic, standard therapy-refractory, neuropathic plantar DFUs were assessed in an open-label single-arm clinical trial.

Results

Hypoxic incubation of ABCB5⁺ MSCs led to posttranslational stabilization of the hypoxia-inducible transcription factor 1α (HIF-1α) and upregulation of HIF-1α mRNA levels. HIF-1α pathway activation was accompanied by upregulation of vascular endothelial growth factor (VEGF) transcription and increase in VEGF protein secretion. Upon culture in growth factor-supplemented medium, ABCB5⁺ MSCs expressed the endothelial-lineage marker CD31, and after seeding on gel matrix, ABCB5⁺ MSCs demonstrated formation of capillary-like structures comparable with human umbilical vein endothelial cells. Intramuscularly injected ABCB5⁺ MSCs to mice with surgically induced hindlimb ischemia accelerated perfusion recovery as measured by laser Doppler blood perfusion imaging and enhanced capillary proliferation and vascularization in the ischemic muscles. Adjunctive topical application of ABCB5⁺ MSCs onto therapy-refractory DFUs elicited median wound surface area reductions from baseline of 59% (full analysis set, n = 23), 64% (per-protocol set, n = 20) and 67% (subgroup of responders, n = 17) at week 12, while no treatment-related adverse events were observed.

Conclusions

The present observations identify GMP-manufactured ABCB5⁺ dermal MSCs as a potential, safe candidate for adjunctive therapy of otherwise incurable DFUs and justify the conduct of a larger, randomized controlled trial to validate the clinical efficacy.

Trial registration: ClinicalTrials.gov, NCT03267784, Registered 30 August 2017, https://clinicaltrials.gov/ct2/show/NCT03267784

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03156-9.

Allogeneic ABCB5+ mesenchymal stem cells for treatment-refractory chronic venous ulcers: a phase I/IIa clinical trial

A significant number of chronic venous ulcers (CVUs) fail to heal despite of guideline-conform standard of care. Skin-derived ABCB5+ mesenchymal stem cells (MSCs) can dampen the sustained IL-1β-driven inflammation present in chronic wounds. Based on their wound healing-facilitating effects in a mouse CVU model and an autologous first-in-human study, ABCB5+ MSCs have emerged as a potential candidate for cell-based advanced therapy of non-healing CVUs. In the present interventional, multicenter, single-arm, phase I/IIa clinical trial, subjects whose CVU had emerged as standard therapy-resistant received one or two topical applications of 1×106 allogeneic ABCB5+ MSCs/cm2 wound area in addition to standard treatment. Out of 83 treatment-emergent adverse events, only three were judged related to the cell product; they were mild or moderate and recovered without sequelae. Wound size markedly decreased from baseline to week 12, resulting in a median wound size reduction of 76% (full analysis set, N=31), 78% (per-protocol set, N=27) and 87% (subset of responders; n=21). In conclusion, the study treatment was well tolerated and safe. The treatment elicited a profound wound size reduction within 12 weeks, identifying ABCB5+ MSCs as a potential candidate for adjunctive therapy of otherwise incurable CVUs. These results justify the conduct of a larger, randomized, controlled trial to confirm clinical efficacy.

Temporal and structural patterns of extended-spectrum cephalosporin-resistant Klebsiella pneumoniae incidence in Swiss hospitals

BACKGROUND

Routine surveillance data revealed increasing rates of invasive extended-spectrum cephalosporin-resistant Klebsiella pneumoniae (ESCR-KP) in Switzerland, from 1.3% in 2004 to 8.5% in 2019.

AIM

The main aim of this study was to understand the causes of this recent trend, specifically to identify predictors affecting the incidence of invasive ESCR-KP infections in Switzerland.

METHODS

A retrospective observational multi-centre study was conducted in 21 Swiss hospitals over a period of 11 years (2009-2019). Potential predictor variables for the incidence of invasive ESCR-KP infections were studied with a multiple linear regression model. In an additional analysis, the overall ESCR-KP incidence (all sample sites) was investigated.

FINDINGS

An increasing incidence of invasive ESCR-KP infections from 0.01 to 0.04 patients per 1000 bed-days was observed between 2009 and 2019 and confirmed by multiple linear regression analysis (P < 0.01). ESCR-KP incidence was higher in university hospitals (P < 0.01) and in the French-speaking region than in the German-speaking region (P < 0.01). There was no association with antibiotic consumption. Analysing the overall ESCR-KP incidence (all sample sites) revealed high variability between university hospitals, mainly due to a high proportion of patients with screening isolates at Geneva University Hospital (50% of patients with ESCR-KP).

CONCLUSION

The incidence of invasive ESCR-KP infections increased in Switzerland between 2009 and 2019 and was not associated with antibiotic consumption. Our findings indicate that, in this low-incidence setting, structural factors such as the hospital type and the linguistic region play a more important role in relation to ESCR-KP incidence than the hospital's antibiotic consumption.

ARE STEM CELL MARKER EXPRESSION AND CD133 ANALYSIS RELEVANT TO DIFFERENTIATE COLORECTAL CANCER?

Background:

CD133 and AXL have been described as cancer stem cell markers, and c-MYC as a key regulatory cellular mechanism in colorectal cancer (CRC).

Aim:

Evaluate the prognostic role of the biomarkers CD133, AXL and c-MYC and their association with clinicopathologic characteristics in colorectal adenocarcinomas and adenomas.

Methods:

A total of 156 patients with UICC stage I-IV adenocarcinomas (n=122) and adenomas (n=34) were analyzed. Tissue microarrays (TMA) from primary tumors and polyps for CD133, c-MYC and AXL expression were performed and analyzed for their significance with clinicopathologic characteristics.

Results:

Poorly differentiated adenocarcinomas and disease progression were independent risk factors for poor overall survival. The median overall survival time was 30 months. Positive CD133 expression (35.9% of all cases), particularly of right-sided CRCs (44.8% of the CD133+ cases), was negatively correlated with death in the univariate analysis, which did not reach significance in the multivariate analysis. c-MYC (15.4% of all cases) was predominantly expressed in advanced-stage patients with distant (non-pulmonary/non-hepatic) metastasis. AXL expression was found only occasionally, and predominantly dominated in adenomas, with less penetrance in high-grade dysplasia.

Conclusions:

CD133 expression was not associated with inferior overall survival in CRC. While AXL showed inconclusive results, c-MYC expression in primary CRCs was associated with distant metastasis.

Abstract 1758: Pro-inflammatory serum marker profiles that lack upregulated IL-17 are characteristic for pancreatic cancer and require for further anti-tumor immune response and strategies

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer with 5-year survival rates between 5-8%. Chronic inflammation of the pancreas and pancreatitis is thought to be a risk factor in PDAC. The aim of this study was to elucidate characteristic pro-inflammatory cytokines and chemokines including IL-17 profiles in human pancreatic cancer. A total of 186 individuals with confirmed PDAC (n=116), chronic pancreatitis (n=32), and healthy volunteers (n=38) were included in the study. The histological stage of the tumor was determined according to the Union for International Cancer Control (UICC) TNM staging system. Tumors were evaluated for stage and differentiation grade. Data concerning age, gender, level of wall infiltration, lymph node metastasis, and distant metastases were collected in a database. Additional clinical characteristics necessary for statistical analysis of the data from the study population were collected from the Tumor Registry. Inflammation-related cytokines and chemokines in IL-17 pathway among the patients were analyzed from serum obtained pre-operatively and compared with healthy controls. Moreover, the KEGG PATHWAY, a collection of manually drawn pathway maps on molecular interaction, reaction and relation networks was used for IL-17 pathway analysis. Non-parametric tests and correlation tests were utilized to compare the factors among three groups for statistical analysis. Pancreatitis patients showed highest expression in inflammatory cytokines and chemokine panels while those with PDAC showed different profiles. Pro-inflammatory cytokines including IL-5, IL-6, CXCL8, CCL2, TNF-alpha, and IFN-gamma revealed higher expression in PDAC patients than healthy volunteers (P&lt;0.05). Anti-inflammatory cytokines like IL-13 demonstrated lower expression in PDAC patients than healthy controls (P&lt;0.05), which was likewise observed for IL-17. Interestingly, PDAC patients with distant metastases showed lower pro-inflammatory expression profiles than those with localized tumors. Moreover, correlation analysis demonstrated that IL-17 was correlated with IL-13 and GM-CSF expression (P&lt;0.05). In conclusion, we provide evidence that PDAC patients are characterized by dominant expression of pro-inflammatory cytokine profiles, diminished IL-17 level within their serum, and also anti-inflammatory mediators within is in part divergent from other solid cancers. The IL-17 signaling. may therefore play a different role in the inflammatory pathway in pancreatic cancer.

Citation Format: Yueming Luo, Martin Gasser, Amrendra Ajay, Li-LI Hsiao, Ana Maria Waaga-Gasser. Pro-inflammatory serum marker profiles that lack upregulated IL-17 are characteristic for pancreatic cancer and require for further anti-tumor immune response and strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1758.

Abstract 967: Phosphodiesterase 4D depletion enhances anti-tumor effects of tyrosine kinase inhibitor in renal cell carcinoma involving CRAF-ERK pathway

Clear cell renal cell carcinoma (ccRCC) is the most lethal form of kidney cancer. Small molecule Vascular Endothelial Growth Factor Receptor (VEGFR) inhibitors are widely used but are not curative and various resistant mechanisms have been described. Previous studies have indicated a crosstalk between the cAMP pathway and the MAPK pathway, and the elevation of cAMP levels by Phosphodiesterase 4 (PDE4) inhibition can result in growth arrest and/or cell death. In this study we focused on the effects of PDE4 in ccRCC. We showed for the first time that PDE4D is the dominant subtype of PDE4 in kidney. PDE4D depletion in ccRCC, Caki-1 cells, using CRISPR Knock Out (KO) enhanced sensitivity of Tyrosine Kinase Inhibitor (TKI), sorafenib and increased cytotoxicity. We also showed synergistic effects of PDE4 inhibitor, roflumilast and sorafenib, in increasing cytotoxicity of ccRCC in the absence of PDE4D. Our results further demonstrated that PDE4D deficiency increased intracellular cAMP levels and resulted in downregulation of MAPK but not PI3K/AKT signaling in a CRAF dependent manners. In conclusion, we provide a preclinical rationale for dual PDE4/VEGFR inhibition in patients with ccRCC. While the MAPK signaling pathway is activated in ccRCC, dual inhibitions may improve the anti-tumor effects in patients with proven CRAF signaling activation.

Citation Format: Minghua Cao, Amrandra K. Ajay, Martin Gasser, Li-LI Hsiao, Ana Maria Waaga-Gasser. Phosphodiesterase 4D depletion enhances anti-tumor effects of tyrosine kinase inhibitor in renal cell carcinoma involving CRAF-ERK pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 967.

ARE STEM CELL MARKER EXPRESSION AND CD133 ANALYSIS RELEVANT TO DIFFERENTIATE COLORECTAL CANCER?

Background:

CD133 and AXL have been described as cancer stem cell markers, and c-MYC as a key regulatory cellular mechanism in colorectal cancer (CRC).

Aim:

Evaluate the prognostic role of the biomarkers CD133, AXL and c-MYC and their association with clinicopathologic characteristics in colorectal adenocarcinomas and adenomas.

Methods:

A total of 156 patients with UICC stage I-IV adenocarcinomas (n=122) and adenomas (n=34) were analyzed. Tissue microarrays (TMA) from primary tumors and polyps for CD133, c-MYC and AXL expression were performed and analyzed for their significance with clinicopathologic characteristics.

Results:

Poorly differentiated adenocarcinomas and disease progression were independent risk factors for poor overall survival. The median overall survival time was 30 months. Positive CD133 expression (35.9% of all cases), particularly of right-sided CRCs (44.8% of the CD133+ cases), was negatively correlated with death in the univariate analysis, which did not reach significance in the multivariate analysis. c-MYC (15.4% of all cases) was predominantly expressed in advanced-stage patients with distant (non-pulmonary/non-hepatic) metastasis. AXL expression was found only occasionally, and predominantly dominated in adenomas, with less penetrance in high-grade dysplasia.

Conclusions:

CD133 expression was not associated with inferior overall survival in CRC. While AXL showed inconclusive results, c-MYC expression in primary CRCs was associated with distant metastasis.

IS THERE A CLINICAL PATHOLOGICAL CORRELATION OF COLORECTAL ADENOCARCINOMA WITH THE IMMUNOHISTOCHEMICAL EXPRESSION OF OPN AND ABCB5?

Background:

Studies with biomarkers in TMA (tissue microarray) have been showing important results regarding its expression in colon cancer.

Aim:

Correlate the expression profile of the OPN and ABCB5 biomarkers with the epidemiological and clinicopathological characteristics of the patients, the impact on the progression of the disease and the death.

Method:

A total of 122 CRC patients who underwent surgical resection, immunomarking and their relationship with progression and death events were evaluated.

Result:

The average age was 61.9 (±13.4) years. The cases were distributed in 42 (35.9%) in the ascending/transverse colon, 31 (26.5%) in the sigmoid, 27 in the rectum (23.1%), 17 (14.5%) in the descending colon. Most patients had advanced disease (stages III and IV) in 74 cases (60.9%). There was a predominance of moderately differentiated tumors in 101 samples (82.8%); despite this, the poorly differentiated subtype proved to be an independent risk factor for death in 70%. Metastasis to the liver proved to be an independent risk factor for death in 75% (18/24), as well as patients with primary rectal tumors in 81.5% (22/27).

Conclusion:

The immunohistochemical expression of the OPN and ABCB5 markers was not associated with epidemiological and clinicopathological characteristics. Regarding the progression of disease and death, it was not possible to observe a correspondence relationship with the evaluated markers.

Abstract PO001: Results from a preclinical study to evaluate the efficacy of polyvalent immunoglobulins on the imbalance of (anti-)inflammatory immune cell responses in clinical colorectal cancer

Introduction: The purpose of this study was to determine the efficacy of an immunoglobulin concentrate on dysregulated inflammatory responses in patients with colorectal cancer (CRC). Recent findings have shown that CRC is associated with dysbiosis of the gut microbiome and frequently a compromised gut barrier, resulting in prolonged and smoldering endotoxin leakage into the circulation. Subclinical local and systemic microinflammation is suggested to facilitate metastasis formation. Previous studies have pointed to the capacity of polyvalent immunoglobulins to neutralize endotoxins and pathogens on gut epithelial surfaces to abrogate inflammatory responses and thereby tumor recurrence. The effects of KMP01D, a colostrum preparation with a multitude of immunoglobulins against gram-negative/positive bacteria and viruses, on pro-/anti-inflammatory cytokine responses and apoptosis were determined ex vivo.

Methods: Peripheral blood and tumor-derived mononuclear cells (MNC) from CRC patients at UICC stages I–IV (n=48) operated at our Center for Operative Medicine/Comprehensive Cancer Center and treated under current guidelines for (neo-)adjuvant therapy were further investigated. Expression of CD14, CD68, Toll-like receptor(TLR) 4, and insulin-like growth factor (IGF)-1 with/without co-incubation of KMP01D as well as immune cell apoptosis was analyzed by flow cytometry, RT PCR, immunohistochemistry, and Elisa in each patient.

Results: KMP01D increased interleukin (IL)-10 and IL-13 anti-inflammatory cytokine expression in peripheral blood MNCs (UICC I-III). More interestingly, it likewise decreased secretion of IL-1β, IL-6, IFN-γ, TNF-α, and IL-12 driven inflammation as well as IGF-1. Moreover, CD14/CD68 and TLR4 expression critically involved in endotoxin signaling was downregulated in PBMCs and tumor-infiltrating MNCs. CD14+Fas+/TUNEL+ PBMCs and tumor-derived MNCs indicating apoptosis were likewise enhanced under KMP01D co-incubation. Addition of vitamin D3 known as a regulatory factor in immune responses demonstrated additive anti-inflammatory effects in vitro.

Conclusions: Inflammatory immune responses are significantly and stage-dependently upregulated which negatively impacts anti-tumor-specific immune reactivity, immune cell apoptosis and prognosis in CRC patients despite modern adjuvant treatment protocols. KMP01D produced from natural bovine sources and composed of a multitude of immunoglobulin activity (IgG1/2 and Lactoferrin) demonstrates highly ex vivo efficacy on downregulation of inflammatory cytokine responses in PBMCs and normalized immune cell apoptosis in CRC patients. Together with previous clinical data our results strongly suggest that KMP01-mediated endotoxin and pathogen neutralization and thereby mitigated chronic inflammation can be a highly valuable add-on instrument in the treatment of CRC patients to downregulate stage-dependently their local and systemic inflammation and risk for metastasis formation.

Citation Format: Martin Gasser, Reinhard Lissner, Li-Li Hsiao, Ana Maria Waaga-Gasser. Results from a preclinical study to evaluate the efficacy of polyvalent immunoglobulins on the imbalance of (anti-)inflammatory immune cell responses in clinical colorectal cancer [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO001.

Topical therapy with rhubarb navel plasters in patients with chronic constipation: Results from a prospective randomized multicenter study

ETHNOPHARMACOLOGICAL RELEVANCE

Constipation is a functional gastrointestinal disorder and one of the most prevalent conditions encountered in primary care settings. Rhubarb navel dressings have been used for more than 2,000 years in Chinese medicine to treat constipation. However, the effect of topical rhubarb administration has still not been well recognized and this strategy is not yet established as an evidence-based approach.

AIM OF THE STUDY

In this study, we performed a prospective multicentric randomized controlled trial to evaluate the efficacy and safety of rhubarb navel plasters for patients with chronic constipation.

MATERIALS AND METHODS

A total of 374 patients from six teaching hospitals were prospectively included between 09/2016 and 10/2017 in the study based on Rome III criteria. All participants were randomly assigned (1:1) into verum/placebo group and given either Rheum officinale rhubarb powder or a placebo flour stick on the navel for 6 h/day/8 days. Primary outcome measures were the Cleveland Constipation Score (CCS) for the feces condition and Bristol Stool Scale (BSS) for stool consistency and 24 h defecation frequency.

RESULTS

The groups demonstrated no statistical differences in demographic data, clinical diagnoses and concomitant medication at baseline. In patients treated with the verum CCS was 5.61 (day 8, 95% CI 5.15-6.07) compared to 8.62 (95% CI 8.07-9.18) in placebo-treated controls (P < 0.001). The mean change of CCS at the end of treatment (day 8 versus [vs] day 0) was 6.04 in verum-treated vs 2.73 in placebo-treated controls (P < 0.001). Also 24 h defecation frequency (BSS) showed superior results (day 5: 0.84 vs 0.62, 95% CI 0.67-0.80, P < 0.001; day 6: 0.82 vs 0.60, 95% CI 0.64-0.78, P < 0.01 and day 8: 0.82 vs 0.60, 95% CI 0.64-0.78, P < 0.01) and better BSS type classification during treatment than controls (P < 0.05). No significant differences in adverse events between both groups became obvious.

CONCLUSION

Rhubarb navel plaster administration over an 8-day-treatment period resulted in significantly improved bowel function as demonstrated by the CCS, 24 h defecating frequency and BSS. Our results suggest that rhubarb navel plasters represent a feasible, safe and efficient application route for the treatment of patients suffering from chronic constipation.

Ex vivo-expanded highly pure ABCB5+ mesenchymal stromal cells as Good Manufacturing Practice-compliant autologous advanced therapy medicinal product for clinical use: process validation and first in-human data

Background aim:

Mesenchymal stromal cells (MSCs) hold promise for the treatment of tissue damage and injury. However, MSCs comprise multiple subpopulations with diverse properties, which could explain inconsistent therapeutic outcomes seen among therapeutic attempts. Recently, the adenosine triphosphate-binding cassette transporter ABCB5 has been shown to identify a novel dermal immunomodulatory MSC subpopulation.

Methods:

The authors have established a validated Good Manufacturing Practice (GMP)-compliant expansion and manufacturing process by which ABCB5⁺ MSCs can be isolated from skin tissue and processed to generate a highly functional homogeneous cell population manufactured as an advanced therapy medicinal product (ATMP). This product has been approved by the German competent regulatory authority to be tested in a clinical trial to treat therapy-resistant chronic venous ulcers.

Results:

As of now, 12 wounds in nine patients have been treated with 5 × 10⁵ autologous ABCB5⁺ MSCs per cm² wound area, eliciting a median wound size reduction of 63% (range, 32–100%) at 12 weeks and early relief of pain.

Conclusions:

The authors describe here their GMP- and European Pharmacopoeia-compliant production and quality control process, report on a pre-clinical dose selection study and present the first in-human results. Together, these data substantiate the idea that ABCB5⁺ MSCs manufactured as ATMPs could deliver a clinically relevant wound closure strategy for patients with chronic therapy-resistant wounds.

KMP01D Demonstrates Beneficial Anti-inflammatory Effects on Immune Cells: An ex vivo Preclinical Study of Patients With Colorectal Cancer

Background: Colorectal cancer (CRC) is frequently associated with dysbiosis of the gut microbiome which, together with a compromised gut barrier, can result in perioperative endotoxin leakage into the circulation. Constant local and systemic inflammatory activity is suggested to facilitate metastases formation. Previous studies have pointed to the capacity of a colostrum preparation to neutralize endotoxins within the gastrointestinal tract which could ameliorate associated inflammatory responses and tumor recurrence in affected patients. This study aimed to examine the effects of the colostrum preparation, KMP01D, on the inflammatory activity of patient-derived immune cells. Methods: The effects of KMP01D on pro-/anti-inflammatory cytokine responses and apoptosis were examined ex vivo using immune cells from CRC patients (stages I-IV, n = 48). The expression of CD14, CD68, Toll-like receptor (TLR)4, and insulin-like growth factor (IGF)-1 was also analyzed. Results: KMP01D increased interleukin (IL)-10 and IL-13 anti-inflammatory cytokine expression in patient-derived peripheral blood mononuclear cells (PBMCs). Interestingly, KMP01D also decreased the secretion of IL-1β, IL-6, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-12 inflammatory cytokines, and IGF-1 in these cells. Moreover, CD14 and TLR4 expression involved in endotoxin signaling was downregulated in PBMCs and tumor-derived cells. Apoptosis of immune cells and tumor-derived cells was likewise enhanced with KMP01D. Addition of vitamin D3 as a cofactor demonstrated enhanced anti-inflammatory effects. Conclusions: KMP01D demonstrated beneficial ex vivo effects on inflammatory cytokine responses in PBMCs and enhanced apoptosis of immune cells from CRC patients. In line with previous clinical trials, we present new evidence endorsing KMP01D as a treatment strategy to regulate stage-dependent local and systemic inflammation in CRC patients.

Expression of Tumor-mediated CD137 ligand in human colon cancer indicates dual signaling effects

CD137-targeting immune therapy, which activates anti-tumor T effector cell responses, seems to be an attractive concept in clinical oncology. Recent evidence has demonstrated that tumor cells besides T cells and antigen-presenting cells are able to express CD137 and CD137L. Here we aimed to identify CD137/CD137L expression in established colon cancer cell lines and primary tumors (UICC stages I-IV) from patients with documented long-term follow-up. CD137/CD137L expression was highly upregulated in early to late-stage tumors while the inverse was observed in patient-derived peripheral blood mononuclear cells. High CD137L expression within primary tumors was mediated by tumor cells and significantly correlated with the occurrence of distant metastases and shortened survival in advanced stages of disease (UICC stage IV). Interestingly, induced tumor cell signaling via CD137L on its surface in vitro resulted in dual effects: (i) reduced tumor cell proliferation suggesting inhibitory signaling in all investigated cancers and (ii) increased epithelial-to-mesenchymal transition signaling events. Taken together CD137/CD137L expression was stage-dependently upregulated with shortened survival in patients with highly CD137L-expressing tumors. Our clinical and experimental data suggest that colon cancer cells predominantly express CD137L and thereby have negative impact on overall survival through a process of reverse signaling. Beside agonistic CD137 antibody therapy to foster T effector cell responses, CD137L-mediated intervention strategies may become instrumental to circumvent relapsed tumor growth through induced epithelial-to-mesenchymal transition and consecutive metastases formation.

Tissue microarray technology and collagen evaluation to analyze surgical trauma performed with usual blade or ultrasonic harmonic scalpels in rats

PURPOSE

To compare wound healing performed with cold blade (CSB) and ultrasonic harmonic scalpel (UHS) in the abdominal aponeurosis of rats.

METHODS

Eighty Wistar rats divided into two groups and underwent midline incision in the linea alba with cold blade and harmonic ultrasonic scalpel. Analysis were performed in subgroups of 10 animals after 3, 7, 14 and 21 days. Macroscopically was observed the presence of hematoma, infection, wound dehiscence, fistula and adherences. Microscopically were used collagen and immunohistochemical staining methods.

RESULTS

Macroscopic, complications showed no statistical difference. Immunohistochemical analysis for MMP-9 was more intense in UHS group (p<0.05). TGF β presented its lower expression in UHS group at 14 and 21 days, with no statistical difference at 3 and 7 days (p<0.05). α-AML expression appeared higher in UHS group after 14 days and remained similar in others (p<0.05). Collagen deposition had no change in type I, and increased in type III in UHS; at 7th day the deposition was higher in CSB group; at 14th was similar in both groups (p<0.001).

CONCLUSION

UHS compared to the CSB has higher lesion area at the time of the incision; as well as it led to the delay of regeneration and scar maturation process.

ATP-binding cassette member B5 (ABCB5) promotes tumor cell invasiveness in human colorectal cancer

ABC member B5 (ABCB5) mediates multidrug resistance (MDR) in diverse malignancies and confers clinically relevant 5-fluorouracil resistance to CD133-expressing cancer stem cells in human colorectal cancer (CRC). Because of its recently identified roles in normal stem cell maintenance, we hypothesized that ABCB5 might also serve MDR-independent functions in CRC. Here, in a prospective clinical study of 142 CRC patients, we found that ABCB5 mRNA transcripts previously reported not to be significantly expressed in healthy peripheral blood mononuclear cells are significantly enriched in patient peripheral blood specimens compared with non-CRC controls and correlate with CRC disease progression. In human-to-mouse CRC tumor xenotransplantation models that exhibited circulating tumor mRNA, we observed that cancer-specific ABCB5 knockdown significantly reduced detection of these transcripts, suggesting that the knockdown inhibited tumor invasiveness. Mechanistically, this effect was associated with inhibition of expression and downstream signaling of AXL receptor tyrosine kinase (AXL), a proinvasive molecule herein shown to be produced by ABCB5-positive CRC cells. Importantly, rescue of AXL expression in ABCB5-knockdown CRC tumor cells restored tumor-specific transcript detection in the peripheral blood of xenograft recipients, indicating that ABCB5 regulates CRC invasiveness, at least in part, by enhancing AXL signaling. Our results implicate ABCB5 as a critical determinant of CRC invasiveness and suggest that ABCB5 blockade might represent a strategy in CRC therapy, even independently of ABCB5's function as an MDR mediator.

[Stem cell-based strategies in vascular surgery]

Critical chronic ischemia in patients with underlying arterial occlusive disease requires vascular reconstructive surgery. The limited supply of suitable small-diameter autologous vascular grafts in many patients and obvious disadvantages of synthetic bypass material demand the development of clinically usable tissue-engineered blood vessel substitutes. Despite substantial progress in the field over the last two decades, their implementation into the clinical routine has been challenging. The limited replicative life span of human adult vascular cells and their slow rate of collagenous matrix production in vitro have posed important problems in the development of mechanically robust and biologically functional engineered grafts. With recent advances in stem cell research, new cell sources for vascular tissue engineering have become available. In particular, the discovery of human induced pluripotent stem (iPS) cells derived from adult differentiated cells, as well as of human multipotent adult mesenchymal stem cells without gene modification requirements and related safety concerns, may advance the development of novel autologous cell-based tissue engineering approaches. Here we discuss recent developments in the field of vascular progenitor cells and opportunities and challenges for the clinical translation of stem cell-engineered vascular tissue substitutes.

Exclusive inhibition of PI3K/Akt/mTOR signaling is not sufficient to prevent PDGF-mediated effects on glycolysis and proliferation in colorectal cancer

Platelet-derived growth factor (PDGF) and signaling via its receptors plays a crucial role in tumor cell proliferation and thus may represent an attractive target besides VEGF/EGFR-based antibody therapies. In this study we analyzed the influence of PDGF in colorectal cancer. PDGF was expressed intensively in early and even more intensively in late stage primary CRCs. Like VEGF, PDGF enhanced human colon cancer proliferation, and increased oxidative glycolytic activity, and activated HIF1α and c-Myc in vitro. PDGF activated the PI3K/Akt/mTOR pathway while leaving MAPK signaling untouched. Further dissection showed that inhibition of Akt strongly impeded cancer cell growth while inhibition of PI3K did not. MAPK analysis suggested an inhibitory crosstalk between both pathways, thus explaining the different effects of the Akt and PI3K inhibitors on cancer cell proliferation. PDGF stimulates colon cancer cell proliferation, and prevents inhibitor induced apoptosis, resulting in tumor growth. Therefore inhibition of PDGF signaling seems to be a promising target in colorectal cancer therapy. However, due to the multifaceted nature of the intracellular PDGF signaling, careful intervention strategies are needed when looking into specific signaling pathways like PI3K/Akt/mTOR and MAPK.

Hypoxia induces differential expression patterns of osteopontin and CD44 in colorectal carcinoma

The plasma protein osteopontin (OPN) is considered to be a tumor biomarker, where elevated plasma levels are associated with poor prognosis. Additionally, OPN is expressed in the presence of tumor hypoxia, which is an adverse prognostic factor in radiation oncology. One of its receptors, the proposed tumor stem cell marker CD44, is also associated with aggressive tumors, shown for example in colon cancer. The expression of CD44 and its splice variants (particularly CD44v6) can be upregulated by OPN itself. In the present study, we aimed to investigate the influence of hypoxia on the expression of OPN and its binding partners CD44 and CD44v6 in colon carcinoma cell lines in vitro, using SW480, SW620, HT29 and HCT116 cells. Additionally, we investigated the effect of irradiation on the expression pattern of OPN and its ligands, and the influence of hypoxia on the clonogenic survival of the cells after irradiation. While the expression patterns were nearly unaltered by irradiation, hypoxia led to an upregulation of OPN protein expression and an increase in the radioresistance in all tested colorectal carcinoma cell lines. However, a similar clear statement with regard to the expression of CD44 and CD44v6 is not possible. We hypothesize that the OPN receptors differ in their expression pattern between cell lines depending on the degree of their malignancy.

Upregulated Heat Shock Proteins After Hyperthermic Chemotherapy Point to Induced Cell Survival Mechanisms in Affected Tumor Cells From Peritoneal Carcinomatosis

In patients with peritoneal carcinomatosis cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) represents a promising treatment strategy. Here, we studied the role of hyperthermic chemotherapy on heat shock protein (HSP) expression and induction of tumor cell death and survival. HSP27, HSP70, and HSP90 combined with effects on tumor cell proliferation and chemosensitivity were analyzed in human colon cancer. Hyperthermic chemotherapy resulted in significant HSP27/HSP70 and HSP90 gene/protein overexpression in analyzed HT-29/SW480/SW620 colon cancer cells and peritoneal metastases from patients displaying amplified expression of proliferation markers, proliferating cell nuclear antigen and antiapoptotic protein Bcl-xL. Moreover, functionally increased chemoresistance against 5-fluorouracil/mitomycin C and oxaliplatin after hyperthermic chemotherapy points to induced survival mechanisms in cancer cells. In conclusion, the results indicate that intracellular HSP-associated antiapoptotic and proliferative effects after hyperthermic chemotherapy negatively influence beneficial effects of hyperthermic chemotherapy-induced cell death. Therefore, blocking HSPs could be a promising strategy to further improve the rate of tumor cell death and outcome of patients undergoing HIPEC therapy.

Abstract 1237: PDGF induces cell growth and changes in glucose metabolism in colon cancer in the absence of PDGF receptors

Background: The Platelet derived growth factor (PDGF) and its receptors play a major role in inducing proliferation, migration, and angiogenesis by activating intracellular PI3K/Akt/mTOR signaling events in different solid tumors and therefore represent attractive targets in tumor therapy. Recently we showed a PDGF-induced activation of metabolism and proliferation in HT29 colon cancer cells in the absence of specific PDGF receptors. The aim of this study was to analyze PDGFR and VEGFR expression and possible alternative PDGF binding partners in colorectal cancer (CRC).

Methods: Human HT29 colon cancer cells were cultured and stimulated with PDGF in a time-dependent manner. Additionally, VEGFR2 and EGFR inhibition was performed to analyze alternative PDGF signaling events. Whole cell or RNA extracts were analyzed by Western Blot and RT-q-PCR for receptors and PI3K/Akt/mTOR signaling. To investigate the effects of specific receptor inhibition on proliferation, MTS proliferation assays were performed. Moreover, mRNA levels of PDGFR and VEGFR in tumors from patients with CRC were analyzed by RT-qPCR.

Results: Human UICC stage I-IV tumors exhibited a significantly increased PDGFRβ and VEGFR1,2 gene expression. As observed previously, HT29 colon cancer cells showed only positivity for VEGFR1,2, but no PDGFR protein expression. Despite that, stimulation with PDGF resulted in increased proliferation and metabolic changes. In contrast, Caco-2 and SW480 colon cancer cells showed PDGFR and VEGFR expression on protein level. Interestingly, PDGF stimulation increased VEGFR1 and 2 gene expression in HT29 colon cancer cells and secondly inhibition of VEGFR2 and EGFR showed alterations in proliferation and Akt signaling in PDGF stimulated cancer cells.

Conclusion: Despite the absence of PDGF receptors in HT29 colon cancer cells, PDGF induced proliferating and metabolic effects in the tumor cells, suggesting an alternative binding partner on the tumor cell surface. Further investigation of the alternative PDGF binding partners could be of clinical relevance in CRC.

Note: This abstract was not presented at the meeting.

Citation Format: Romana Moench, Tanja Grimmig, Christoph-Thomas Germer, Ana Maria Waaga-Gasser, Martin Gasser. PDGF induces cell growth and changes in glucose metabolism in colon cancer in the absence of PDGF receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1237. doi:10.1158/1538-7445.AM2017-1237

Morbidity and oncologic outcome after saphenous vein-sparing inguinal lymphadenectomy in melanoma patients

BACKGROUND

Inguinal lymph node dissection (LND) is a surgical procedure with a high morbidity rate. Variations in surgical procedure, such as sparing of the saphenous vein, have been proposed to reduce surgical morbidity. While sparing of the saphenous vein has shown promising results in earlier studies, data for this procedure in melanoma patients are rare. In this retrospective study, we report 10-year findings on the effects of saphenous vein-sparing LND on surgical morbidity and oncologic outcomes in melanoma patients.

METHODS

A retrospective analysis of melanoma patients receiving inguinal LND in our facility between 2003 and 2013 was performed. Patients were divided into two groups: the saphenous vein resection group and the vein sparing group. Surgical morbidity, including wound infection, lymphatic fistula, severe bleeding, neurological complications, and chronic lymphedema, as well as regional recurrence-free survival were investigated.

RESULTS

A total of 106 patients were included in this study; of these, the saphenous vein was spared in 41 patients (38.7%). The rate of lymphatic fistula was 51.6 vs. 48.8%, wound infection occurred in 31.3 vs. 24.4%, and patients suffered from chronic lymphedema in 30.0 vs. 26.5% in V. saphena magna resection vs. sparing group. Differences observed, however, were not significant. No difference in regional recurrence-free survival between the two study groups was detected.

CONCLUSIONS

The results of our retrospective analysis could not confirm the promising results reported in earlier studies. Thus, sparing of the saphenous vein appears to be optional.

Clinical Significance of Disseminated Pluripotent Tumor Cell Signature Expression in the Bone Marrow from Patients with Colorectal Cancer

Purpose:

Disseminated tumor cells (DTCs) are critically involved in tumor relapse and survival in several invasive tumors. We previously showed that the ATP-binding cassette (ABC) transporter, ABCB5, is a chemoresistance mediator expressed on specific cell subsets in colorectal cancer (CRC) and other malignancies. This study evaluated the molecular signature expression and its clinical relevance of DTCs in bone marrow from patients with colon cancer.

Methods:

This study included 49 consecutive patients (UICC stage I-IV) that underwent curatively intended or palliative surgery for CRC. We analyzed cells from bone marrow aspirates obtained before surgery and derived from patients that had completed minimally a 5-year follow-up. The gene expression of ABCB5 in comparison to CD133 (molecule for identifying cancer initiating cells), Lgr5 (an intestinal stem cell marker) as well as Cytokeratin (CK) 20 (terminally differentiated tumor cells of epithelial origin) in these cells was evaluated.

Results:

Bone marrow analysis showed differential expression between the analyzed genes. ABCB5 and Lgr5 and to lesser extent CD133 and CK20 genes were significantly expressed in the analyzed cells from bone marrow aspirates while only ABCB5 and Lgr5 were significantly negative associated with tumor progress and overall survival.

Conclusion:

Overexpression of ABCB5 and Lgr5 in bone marrow negatively influenced patient survival pointing to a specific chemo resistant and pluripotent cell subgroup of DTCs in the bone marrow. ABCB5 like Lgr5 positive cells seem to be involved in limited tumor related patient survival, suggesting that ABCB5- and Lgr5-positive cells may be relevant for specific clinical intervention strategies

Toll Like Receptor 2, 4, and 9 Signaling Promotes Autoregulative Tumor Cell Growth and VEGF/PDGF Expression in Human Pancreatic Cancer

Toll like receptor (TLR) signaling has been suggested to play an important role in the inflammatory microenvironment of solid tumors and through this inflammation-mediated tumor growth. Here, we studied the role of tumor cells in their process of self-maintaining TLR expression independent of inflammatory cells and cytokine milieu for autoregulative tumor growth signaling in pancreatic cancer. We analyzed the expression of TLR2, -4, and -9 in primary human cancers and their impact on tumor growth via induced activation in several established pancreatic cancers. TLR-stimulated pancreatic cancer cells were specifically investigated for activated signaling pathways of VEGF/PDGF and anti-apoptotic Bcl-xL expression as well as tumor cell growth. The primary pancreatic cancers and cell lines expressed TLR2, -4, and -9. TLR-specific stimulation resulted in activated MAP-kinase signaling, most likely via autoregulative stimulation of demonstrated TLR-induced VEGF and PDGF expression. Moreover, TLR activation prompted the expression of Bcl-xL and has been demonstrated for the first time to induce tumor cell proliferation in pancreatic cancer. These findings strongly suggest that pancreatic cancer cells use specific Toll like receptor signaling to promote tumor cell proliferation and emphasize the particular role of TLR2, -4, and -9 in this autoregulative process of tumor cell activation and proliferation in pancreatic cancer.

Abstract 2945: Cell stress during HIPEC causes heat shock protein induction and reduced chemosensitivity in human colon cancer

Background: Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising procedure for the treatment of peritoneal carcinomatosis (PC). Heat shock proteins (HSPs) and other proteins involved in cellular repair mechanisms seem to induce cytoprotective processes during HIPEC therapy. Therefore, the aim of this study was to analyze the effects of HIPEC-related conditions on tumor cell proliferation and the expression of HSPs in human colon cancer.

Methods: Human colon cancer cell lines HT29, SW480 and SW620 were exposed to different temperatures (37°C, 41°C, and 43°C) as well as defined cytostatic agents (Oxaliplatin, Mitomycin C, and 5-Fluorouracil). After cellular regeneration (30 min, 24 h, 48 h and 72 h) RNA isolation and whole cell extraction was performed. Gene and protein expression analysis of HSP27, 70, 72 and 90 as well as PCNA, Ki-67, BCl-2 and BCl-Xl were carried out using RT-qPCR and Western blot. Additionally, MTS cell proliferation assays were performed 24 h, 48 h, 72 h and 96 h post treatment. Moreover, AnnexinV apoptosis assays were conducted.

Results: All colon cancer cells exposed to hyperthermic conditions showed initially up-regulated HSP gene expression. Highest expression was found after exposure to 43°C. Combined cytostatic and hyperthermic treatment demonstrated additional increase in HSP27 expression and in other HSPs to a lesser degree. Tumor cells exposed to cytostatic agents showed overall higher HSP gene expression compared to cells without chemotoxic treatment. Similar effects were detected for the expression of the proliferation marker PCNA and anti-apoptotic protein BCl-Xl. Apoptosis assay demonstrated decreased numbers of apoptotic cells at 43°C compared to normothermia. Additionally, proliferation assays revealed reduced chemosensitivity in cells treated with hyperthermia.

Conclusion: Desired effects of hyperthermia used in HIPEC therapy to achieve anti-proliferative and apoptosis inducing effects seem to be negatively influenced by cell stress mediated repair mechanisms in colon cancer. Our in vitro findings suggest analyzed HSPs to be significantly involved in this hyperthermia and chemotoxicity mediated cellular repair mechanisms. While initial increase in HSP expression can counteract cytotoxic effects during HIPEC therapy their prolonged expression may promote lasting resistance to cellular stress.

Citation Format: Tanja Grimmig, Kerstin Kloos, Rebecca Thumm, Romana Moench, Christoph T. Germer, Ana Maria Waaga-Gasser, Martin Gasser. Cell stress during HIPEC causes heat shock protein induction and reduced chemosensitivity in human colon cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2945.

Abstract 4879: Cancer cell-mediated signaling of TLR 2, 4, and 9 causes activation of PI3K/Akt/mTOR pathway and induces tumor cell proliferation in pancreatic cancer

Background: Toll like receptor (TLR) ligands are in clinical use for the immunotherapy of different cancers. They are supposed to induce an inflammatory immune response against the tumor. Interestingly, several studies showed that TLRs were expressed by cancer cells in different tumor entities and that their activation can contribute to an inflammatory microenvironment. Yet, for pancreatic cancer, TLR expression and its impact in tumor cells is only poorly understood. Therefore this study analyzed the influence of TLR2, 4, and 9 expression and activation on tumor cell signaling and proliferation in pancreatic cancer.

Methods: The expression of TLR 2, 4, and 9 was analyzed in vitro in several established as well as primary human pancreatic cancer cell lines by qRT-PCR and Western Blot. TLR stimulation was then performed in BxPC-3, MIA Paca2, and PacaDD135 cells using the TLR ligands oligodeoxyribonucleotide2006 (ODN2006), lipoteichonic acid of Staphylococcus aureus (LTA-SA) and High-Mobility Group Box 1 (HMGB1). Expression of MyD88 and pAkt was then analyzed by Western Blot. Functional analysis on proliferation (ATP assay) and cytokine expression (Luminex) was additionally performed.

Results: Expression of TLR2, 4 and/or 9 was demonstrated in all investigated human pancreatic cancer cell lines. Receptor activation by single or combined use of TLR ligands resulted in increased MyD88 and pAkt (Ser473) expression. Additionally, up-regulated anti-apoptotic protein Bcl-2 expression was found in stimulated cells, but not in the unstimulated cells. Furthermore, TLR activation resulted in the production of the interleukin(IL)-6, IL-8 and tumor necrosis factor á (TNF-á). Interestingly, tumor cell proliferation was increased within 24 and 48 hours of stimulation.

Conclusion: Our results demonstrate TLR2, 4 and/or 9 expression in all human pancreatic cancer cell lines. Additionally, our findings on TLR activation suggest chronic inflammation-mediated TLR signaling to negatively influence tumor cell apoptosis and to shift the cytokine release in pancreatic cancer towards an inflammatory microenvironment. These findings emphasize the particular role of TLR2, 4 and 9 and their activation in pancreatic cancer, outlining their relevance as potential targets for cancer therapy.

Citation Format: Jennifer Kreckel, Tanja Grimmig, Romana Moench, Christoph T. Germer, Martin Gasser, Ana Maria Waaga-Gasser. Cancer cell-mediated signaling of TLR 2, 4, and 9 causes activation of PI3K/Akt/mTOR pathway and induces tumor cell proliferation in pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4879.

Mimicking Metastases Including Tumor Stroma: A New Technique to Generate a Three-Dimensional Colorectal Cancer Model Based on a Biological Decellularized Intestinal Scaffold

Tumor models based on cancer cell lines cultured two-dimensionally (2D) on plastic lack histological complexity and functionality compared to the native microenvironment. Xenogenic mouse tumor models display higher complexity but often do not predict human drug responses accurately due to species-specific differences. We present here a three-dimensional (3D) in vitro colon cancer model based on a biological scaffold derived from decellularized porcine jejunum (small intestine submucosa+mucosa, SISmuc). Two different cell lines were used in monoculture or in coculture with primary fibroblasts. After 14 days of culture, we demonstrated a close contact of human Caco2 colon cancer cells with the preserved basement membrane on an ultrastructural level as well as morphological characteristics of a well-differentiated epithelium. To generate a tissue-engineered tumor model, we chose human SW480 colon cancer cells, a reportedly malignant cell line. Malignant characteristics were confirmed in 2D cell culture: SW480 cells showed higher vimentin and lower E-cadherin expression than Caco2 cells. In contrast to Caco2, SW480 cells displayed cancerous characteristics such as delocalized E-cadherin and nuclear location of β-catenin in a subset of cells. One central drawback of 2D cultures—especially in consideration of drug testing—is their artificially high proliferation. In our 3D tissue-engineered tumor model, both cell lines showed decreased numbers of proliferating cells, thus correlating more precisely with observations of primary colon cancer in all stages (UICC I-IV). Moreover, vimentin decreased in SW480 colon cancer cells, indicating a mesenchymal to epithelial transition process, attributed to metastasis formation. Only SW480 cells cocultured with fibroblasts induced the formation of tumor-like aggregates surrounded by fibroblasts, whereas in Caco2 cocultures, a separate Caco2 cell layer was formed separated from the fibroblast compartment beneath. To foster tissue generation, a bioreactor was constructed for dynamic culture approaches. This induced a close tissue-like association of cultured tumor cells with fibroblasts reflecting tumor biopsies. Therapy with 5-fluorouracil (5-FU) was effective only in 3D coculture. In conclusion, our 3D tumor model reflects human tissue-related tumor characteristics, including lower tumor cell proliferation. It is now available for drug testing in metastatic context—especially for substances targeting tumor–stroma interactions.

Abstract B28: The stem cell gene ABCB5 mediates colorectal cancer resistance to apoptosis

Cancer stem cells (CSC) responsible for disease progression and therapeutic resistance have been identified in several human malignancies, including colorectal cancer (CRC). However, the molecular mechanisms through which CSC drive tumor growth are incompletely understood. ABCB5, a member of the ATP-binding cassette superfamily of active transporters, serves as a CSC-specific multidrug resistance mechanism in diverse human malignancies. Additionally, ABCB5 has recently been demonstrated to function as an anti-apoptotic gene in tissue-specific non-malignant stem cells. Here we demonstrate that ABCB5 also serves an anti-apoptotic role required for CSC maintenance in human cancer. Targeted inhibition of ABCB5, previously shown to be preferentially expressed on CD133-positive CRC stem cells, induced tumor cell apoptosis in vitro and in vivo and inhibited human CRC growth in NSG recipient mice. Mechanistically, ABCB5-positive tumor cell ablation through monoclonal antibody-mediated blockade or shRNA-mediated gene knockdown resulted in diminished production of the receptor tyrosine kinase AXL, a pro-tumorigenic molecule identified herein to be preferentially produced by CRC stem cells. Restoration of AXL expression through gene transfection in ABCB5 knockdown tumors partially restored tumor growth, demonstrating that ABCB5-positive CRC stem cells drive tumorigenicity at least in part through production of AXL. Our results establish a novel anti-apoptotic function of ABCB5 in human cancer and indicate that targeted blockade of ABCB5 represents a novel strategy for CSC eradication, independent of its previously established function as a multidrug resistance mediator.

Citation Format: Qin Guo, Gretchen Berg, Brian J. Wilson, Gabriel Gonzalez, Jie Ma, Jason S. Gold, Bisweswar Nandi, Qin Huang, Qian Zhan, George F. Murphy, Ana Maria Waaga-Gasser, Christine G. Lian, Markus H. Frank, Martin Gasser, Natasha Frank. The stem cell gene ABCB5 mediates colorectal cancer resistance to apoptosis. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr B28.

A prospective study on histone γ-H2AX and 53BP1 foci expression in rectal carcinoma patients: correlation with radiation therapy-induced outcome

BACKGROUND

The prognostic value of histone γ-H2AX and 53BP1 proteins to predict the radiotherapy (RT) outcome of patients with rectal carcinoma (RC) was evaluated in a prospective study. High expression of the constitutive histone γ-H2AX is indicative of defective DNA repair pathway and/or genomic instability, whereas 53BP1 (p53-binding protein 1) is a conserved checkpoint protein with properties of a DNA double-strand breaks sensor.

METHODS

Using fluorescence microscopy, we assessed spontaneous and radiation-induced foci of γ-H2AX and 53BP1 in peripheral blood mononuclear cells derived from unselected RC patients (n = 53) undergoing neoadjuvant chemo- and RT. Cells from apparently healthy donors (n = 12) served as references.

RESULTS

The γ-H2AX assay of in vitro irradiated lymphocytes revealed significantly higher degree of DNA damage in the group of unselected RC patients with respect to the background, initial (0.5 Gy, 30 min) and residual (0.5 Gy and 2 Gy, 24 h post-radiation) damage compared to the control group. Likewise, the numbers of 53BP1 foci analyzed in the samples from 46 RC patients were significantly higher than in controls except for the background DNA damage. However, both markers were not able to predict tumor stage, gastrointestinal toxicity or tumor regression after curative RT. Interestingly, the mean baseline and induced DNA damage was found to be lower in the group of RC patients with tumor stage IV (n = 7) as compared with the stage III (n = 35). The difference, however, did not reach statistical significance, apparently, because of the limited number of patients.

CONCLUSIONS

The study shows higher expression of γ-H2AX and 53BP1 foci in rectal cancer patients compared with healthy individuals. Yet the data in vitro were not predictive in regard to the radiotherapy outcome.

Abstract 1244: Hyperthermia and chemotherapy mediated effects on tumor cell proliferation and heat shock protein expression in human colon cancer

In patients with peritoneal carcinomatosis (PC) of gastrointestinal cancer hyperthermic intraperitoneal chemotherapy (HIPEC) represents a promising treatment option integrated into multimodal concepts. Heat shock proteins (HSP) play a major role in cellular stress response conferring increased resistance in tumor cells. Therefore we analyzed HSP expression profiles in tumor cells exposed to hyperthermic and chemotherapeutic stress. To mimic HIPEC-like conditions HT29 colon cancer cells were exposed to varying hyperthermic conditions for 60 min with additional 5-fluorouracil (5-FU) treatment. HSP expression was analyzed 30 min, 24 h, 48 h and 72 h after treatment using Western Blot and RT-qPCR. Untreated cells cultivated at 37°C served as controls. Additionally, effects on tumor cell proliferation were determined 24 h, 48 h and 72 h after treatment by MTS-assay. Hyperthermia caused temperature dependent upregulation of HSP27, HSP70, HSP72, and HSP90 gene and protein expression that was further increased by additional cytotoxic 5-FU treatment. 5-FU initiated progressive rise in HSP gene expression up to 72 h after 1 h exposure at normothermia as well as under hyperthermia. After isolated hyperthermia tumor cell proliferation was recovered at 72 h. Antiproliferative effects of 5-FU could not be enhanced by further increased hyperthermia. Antiproliferative effects of hyperthermia induced during HIPEC therapy seem to be negatively influenced by highly conserved HSP mechanisms. Our findings suggest that HSP27, HSP70/72, and HSP90 are significantly involved in hyperthermia and chemotoxicity mediated cell stress repair mechanisms. While initial increase in HSP expression can counteract cytotoxic effects during HIPEC therapy long-term elevated expression levels may cause lasting resistance to cellular stress.

Note: This abstract was not presented at the meeting.

Citation Format: Tanja Grimmig, Rebeca Thumm, Romana Moench, Eva M. Moll, Christoph T. Germer, Ana Maria Waaga-Gasser, Martin Gasser. Hyperthermia and chemotherapy mediated effects on tumor cell proliferation and heat shock protein expression in human colon cancer. [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 1244. doi:10.1158/1538-7445.AM2015-1244

Abstract 3917: PDGF induces cell growth and glycolysis in colon cancer

The platelet derived growth factor (PDGF) plays an important role in several solid tumors. Involved in cell migration and proliferation primarily of stromal cells in cancers PDGF represents a key target in cancer therapy. The aim of this study was to analyze the specific role of PDGF on tumor cell proliferation and metabolism in colorectal cancer (CRC). The human colon cancer cell line HT-29 was cultured and stimulated time-dependently with PDGF. Additionally, inhibition of the PI3k/Akt/mTOR-pathway was performed simultaneously to PDGF stimulation. Whole cell and RNA extracts were analyzed by Western Blot and RT-q-PCR for the PI3k/Akt/mTOR-pathway and components of cellular metabolism. To investigate the effects of PDGF on proliferation MTS assays were performed. Additionally, mRNA levels of PDGF and metabolic factors in tumors from patients with CRC were analyzed by RT-qPCR. PDGF stimulation resulted in increased HT29 cell proliferation compared to untreated controls. Blocking of Akt resulted in inhibition of pS6, activation of Retinoblastoma (Rb) and reduced tumor cell growth. Additionally, under stimulation a higher glycolytic rate was observed while oxygen consumption remained unaltered. Investigated tumors from patients with CRC showed a stage-dependent increase in PDGF expression and a boosted glycolytic rate. The cytokine PDGF induced proliferation accompanied with an altered glycolysis in HT-29 colon cancer. An increased glycolysis and tumor cell proliferation support accelerated cell proliferation and tumor growth. The growth reducing effect of Akt inhibition indicates the PI3K/Akt/mTOR-pathway to play a crucial role in CRC progression and therefore could be an important target in cancer therapy.

Note: This abstract was not presented at the meeting.

Citation Format: Romana Moench, Vinicius Kannen, Tanja Grimmig, Christoph T. Germer, Martin Gasser, Ana Maria Waaga-Gasser. PDGF induces cell growth and glycolysis in colon cancer. [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 3917. doi:10.1158/1538-7445.AM2015-3917

TLR7 and TLR8 expression increases tumor cell proliferation and promotes chemoresistance in human pancreatic cancer

Chronic inflammation as an important epigenetic and environmental factor for putative tumorigenesis and tumor progression may be associated with specific activation of Toll-like receptors (TLR). Recently, carcinogenesis has been suggested to be dependent on TLR7 signaling. In the present study, we determined the role of both TLR7 and TLR8 expression and signaling in tumor cell proliferation and chemoresistance in pancreatic cancer. Expression of TLR7/TLR8 in UICC stage I-IV pancreatic cancer, chronic pancreatitis, normal pancreatic tissue and human pancreatic (PANC1) cancer cell line was examined. For in vitro/in vivo studies TLR7/TLR8 overexpressing PANC1 cell lines were generated and analyzed for effects of (un-)stimulated TLR expression on tumor cell proliferation and chemoresistance. TLR expression was increased in pancreatic cancer, with stage-dependent upregulation in advanced tumors, compared to earlier stages and chronic pancreatitis. Stimulation of TLR7/TLR8 overexpressing PANC1 cells resulted in elevated NF-κB and COX-2 expression, increased cancer cell proliferation and reduced chemosensitivity. More importantly, TLR7/TLR8 expression increased tumor growth in vivo. Our data demonstrate a stage-dependent upregulation of both TLR7 and TLR8 expression in pancreatic cancer. Functional analysis in human pancreatic cancer cells point to a significant role of both TLRs in chronic inflammation-mediated TLR7/TLR8 signaling leading to tumor cell proliferation and chemoresistance.

Oncostatic effects of fluoxetine in experimental colon cancer models

Colon cancer is one of the most common tumors in the human population. Recent studies have shown a reduced risk for colon cancer in patients given the antidepressant fluoxetine (FLX). The exact mechanism by which FLX might protect from colon cancer remains however controversial. Here, FLX reduced the development of different colon tumor xenografts, as well as proliferation in hypoxic tumor areas within them. FLX treatment also decreased microvessel numbers in tumors. Although FLX did not increase serum and tumor glucose levels as much as the colon chemotherapy gold standard Fluorouracil did, lactate levels were significantly augmented within tumors by FLX treatment. The gene expression of the MCT4 lactate transporter was significantly downregulated. Total protein amounts from the third and fifth mitochondrial complexes were significantly decreased by FLX in tumors. Cell culture experiments revealed that FLX reduced the mitochondrial membrane potential significantly and disabled the reactive oxygen species production of the third mitochondrial complex. Furthermore, FLX arrested hypoxic colon tumor cells in the G0/G1 phase of the cell-cycle. The expression of key cell-cycle-related checkpoint proteins was enhanced in cell culture and in vivo experiments. Therefore, we suggest FLX impairs energy generation, cell cycle progression and proliferation in tumor cells, especially under condition of hypoxia. This then leads to reduced microvessel formation and tumor shrinkage in xenograft models.

Incidence, time course and independent risk factors for metachronous peritoneal carcinomatosis of gastric origin--a longitudinal experience from a prospectively collected database of 1108 patients

Background

Comprehensive evidence on the incidence, time course and independent risk factors of metachronous peritoneal carcinomatosis (metaPC) in gastric cancer patients treated with curative intent in the context of available systemic combination chemotherapies is lacking.

Methods

Data from a prospectively collected single-institutional Center Cancer Registry with 1108 consecutive patients with gastric adenocarcinoma (GC), clinical, histological and survival data were analyzed for independent risk factors and prognosis with focus on the development of metaPC. Findings were then stratified to the time periods of treatment with surgery alone, 5-Fluorouracil-only and contemporary combined systemic perioperative chemotherapy strategies, respectively.

Results

Despite R0 D2 gastrectomy (n = 560), 49.6% (±5.4%) of the patients were diagnosed with tumour recurrence and 15.5% (±1.8%) developed metaPC after a median time of 17.7 (15.1-20.3) months after surgery resulting in a tumour related mortality of 100% with a median survival of 3.0 months (2.1 – 4.0). Independent risk factors for the development of metaPC were serosa positive T-category, nodal positive-status, signet cell and undifferentiated gradings (G3/G4). Contemporary systemic combination chemotherapy did not improve the incidence and prognosis of metaPC (p = 0.54).

Conclusions

Despite significant improvements in the overall survival for the complete cohort with gastric cancer over time, those patients with metaPC did not experience the same benefits. The lack of change in the incidence, and persistent poor prognosis of metaPC after curative surgery expose the need for further prevention and/or improved treatment options for this devastating condition.

Novel roles of c-Met in the survival of renal cancer cells through the regulation of HO-1 and PD-L1 expression

The receptor tyrosine kinase c-Met is overexpressed in renal cancer cells and can play major role in the growth and survival of tumor. We investigated how the c-Met-mediated signaling through binding to its ligand hepatocyte growth factor (HGF) can modulate the apoptosis and immune escape mechanism(s) of renal cancer cells by the regulations of novel molecules heme oxygenase-1 (HO-1) and programmed death-1 ligand 1 (PD-L1). We found that HGF/c-Met-mediated signaling activated the Ras/Raf pathway and down-regulated cancer cell apoptosis; and it was associated with the overexpression of cytoprotective HO-1 and anti-apoptotic Bcl-2/Bcl-xL. c-Met-induced HO-1 overexpression was regulated at the transcriptional level. Next, we observed that c-Met induction markedly up-regulated the expression of the negative co-stimulatory molecule PD-L1, and this can be prevented following treatment of the cells with pharmacological inhibitors of c-Met. Interestingly, HGF/c-Met-mediated signaling could not induce PD-L1 at the optimum level when either Ras or HO-1 was knocked down. To study the functional significance of c-Met-induced PD-L1 expression, we performed a co-culture assay using mouse splenocytes (expressing PD-L1 receptor PD-1) and murine renal cancer cells (RENCA, expressing high PD-L1). We observed that the splenocyte-mediated apoptosis of cancer cells during co-culture was markedly increased in the presence of either c-Met inhibitor or PD-L1 neutralizing antibody. Finally, we found that both c-Met and PD-L1 are significantly up-regulated and co-localized in human renal cancer tissues. Together, our study suggests a novel mechanism(s) by which c-Met can promote increased survival of renal cancer cells through the regulation of HO-1 and PD-L1.

CCL2 Chemokine as a Potential Biomarker for Prostate Cancer: A Pilot Study

Purpose

Prostate specific antigen is not reliable in diagnosing prostate cancer (PCa), making the identification of novel, precise diagnostic biomarkers important. Since chemokines are associated with more aggressive disease and poor prognosis in diverse malignancies, we aimed to investigate the diagnostic relevance of chemokines in PCa.

Materials and Methods

Preoperative and early postoperative serum samples were obtained from 39 consecutive PCa patients undergoing radical prostatectomy. Serum from 15 healthy volunteers served as controls. Concentrations of CXCL12, CXCL13, CX3CL1, CCL2, CCL5, and CCL20 were measured in serum by Luminex. The expression activity of CXCR3, CXCR4, CXCR5, CXCR7, CXCL12, CXCL13, CX3CR1, CXCL1, CCR2, CCR5, CCR6, CCR7, CCL2, and CCL5 mRNA was assessed in tumor and adjacent normal tissue of prostatectomy specimens by quantitative real-time polymerase chain reaction. The associations of these chemokines with clinical and histological parameters were tested.

Results

The gene expression activity of CCL2 and CCR6 was significantly higher in tumor tissue compared to adjacent normal tissue. CCL2 was also significantly higher in the blood samples of PCa patients, compared to controls. CCL5, CCL20, and CX3CL1 were lower in patient serum, compared to controls. CCR2 tissue mRNA was negatively correlated with the Gleason score and grading.

Conclusion

Chemokines are significantly modified during tumorigenesis of PCa, and CCL2 is a promising diagnostic biomarker.

Abstract 28: The influence of PDGF and VEGF on tumor proliferation in colon cancer

Background: The platelet derived growth factor (PDGF) and Vascular Endothelial Growth Factor (VEGF) are known to play a crucial role in different tumor entities. Involved in cell migration and proliferation of stromal cells and tumor cells they represent key targets in cancer therapy. The aim of the study was to analyse the specific role of PDGF and VEGF stimulation on tumor cell proliferation and metabolism in colorectal cancer (CRC).

Methods: The human colon cancer cell line HT-29 and Caco-2 were cultured and stimulated with PDGF and VEGF in a time-dependent manner. Whole cell extracts and RNA extracts were analyzed by Western Blot and RT-q-PCR for PDGF- and VEGF receptors and for components of cellular metabolism. To discover effects of PDGF and VEGF on proliferation MTS proliferation assays were performed.

Results: Western Blot analysis and RT-qPCR showed no relevant PDGF-receptor α and β expression in HT-29 cells but varying expression in Caco-2 cells. Stimulation with PDGF or VEGF resulted in increased proliferation compared to untreated controls while simultaneous stimulation with both growth factors did not result in intensified proliferation. Additionally, under stimulation altered expression of various metabolic components was detected.

Conclusion: Our results demonstrate a promoting effect on tumor cell proliferation of both growth factors VEGF and PDGF. Simultaneous stimulation did not show synergistic effects. PDGF in HT-29 cells resulted in proliferation in the absence of PDGF receptors with changes in tumor cell metabolism after stimulation. Moreover in HT-29 cells glucose metabolism changed during stimulation. In conclusion, our data give evidence for direct receptor/ligand signalling of PDGF not only on stromal cells but also on colon cancer cells even in the absence of the PDGF receptor.

Citation Format: Romana Mönch, Tanja Grimmig, Vinicius Kannen, Christoph T. Germer, Ana Maria Waaga-Gasser, Martin Gasser. The influence of PDGF and VEGF on tumor proliferation in colon cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 28. doi:10.1158/1538-7445.AM2014-28

ABCB5 maintains melanoma-initiating cells through a proinflammatory cytokine signaling circuit

The drug efflux transporter ABCB5 identifies cancer stem-like cells (CSC) in diverse human malignancies, where its expression is associated with clinical disease progression and tumor recurrence. ABCB5 confers therapeutic resistance, but other functions in tumorigenesis independent of drug efflux have not been described that might help explain why it is so broadly overexpressed in human cancer. Here we show that in melanoma-initiating cells, ABCB5 controls IL1β secretion, which serves to maintain slow cycling, chemoresistant cells through an IL1β/IL8/CXCR1 cytokine signaling circuit. This CSC maintenance circuit involved reciprocal paracrine interactions with ABCB5-negative cancer cell populations. ABCB5 blockade induced cellular differentiation, reversed resistance to multiple chemotherapeutic agents, and impaired tumor growth in vivo. Together, our results defined a novel function for ABCB5 in CSC maintenance and tumor growth.

Lower CD28+ T cell proportions were associated with CMV-seropositivity in patients with Hashimoto's thyroiditis

BACKGROUND

Alterations in the naive T cell subpopulations have been demonstrated in patients with T cell mediated autoimmune disorders, reminiscent of immunological changes found in the elderly during immunosenescence, including the switch from CD45RA + to CD45RO + T cells and decreased thymic function with increased compensatory proliferative mechanisms, partly associated with latent Cytomegalovirus (CMV) infection. The present study was aimed to investigate proportions of lymphocytes, their relation to CMV-seropositivity and the replicative history of CD45RA + expressing T cells in Hashimoto's thyroiditis (HT, n = 18) and healthy controls (HC, n = 70).

METHODS

Proportions of peripheral T cells were investigated by flow cytometry. The replicative history was assessed by T cell receptor excision circles (TRECs) and relative telomere length (RTL). Expression of CD62L was analyzed by immunohistochemistry in thyroid sections. The role of CMV was assessed by serology, ELISPOT assay and in situ hybridization.

RESULTS

Our results demonstrated a significant increase of CD28-negative T cells, associated with CMV-seropositivity in HT patients. HT showed abundant CD45RO + T cells with peripheral loss of CD62L-expressing CD8 + CD45RA + T cells, the latter mainly depending on disease duration. CD62L was expressed in thyroid lymphocyte infiltrations. The diagnosis of HT and within the HT group CMV-seropositivity were the main determinants for the loss of CD28 expression. RTL was not different between HC and HT. HT showed significantly lower TRECs in CD4 + CD45RA + T cells compared to HC.

CONCLUSIONS

Patients with HT display a peripheral T cell phenotype reminiscent of findings in elderly persons or other autoimmune disorders. Whether these mechanisms are primary or secondary to the immunological alterations of autoimmune conditions should be investigated in longitudinal studies which may open research on new therapeutic regimes for treatment of HT and associated autoimmune diseases.

The role of FOXP3 in disease progression in colorectal cancer patients

The transcription factor forkhead box P3 (FOXP3) has been identified as a marker of CD4⁺CD25⁺ regulatory T cells and is a key determinant of their immunosuppressive functions. FOXP3 has indeed been shown to limit antitumor immune responses during tumor progression. In addition, by expressing FOXP3, tumor cells may evade effector T-cell responses.

Abstract 243: ABCB5 is functionally required for melanoma growth

Melanoma remains a disease with relatively few beneficial treatments currently available, for late-stage patients. The ATP-binding cassette (ABC) transporter ABCB5 has recently been identified as a cell-surface marker for malignant melanoma initiating cells (MMICs; Schatton et al, Nature 2008), opening a new paradigm for investigation of this aggressive cancer. We have previously demonstrated that these ABCB5+ MMICs can evade the host immune system, and also express VEGFR-1, required for efficient tumor formation. However, the possibility that ABCB5 itself plays a functional role in melanoma tumorigenic growth and progression has not been investigated, until now.

To test whether ABCB5 plays a functional role in melanoma growth, or is solely a marker of the cancer stem-cell subset, we generated ABCB5-shRNA knockdown (ABCB5-KD) cell populations in melanoma model cell-lines. To distinguish a bona fide role in intrinsic tumorigenesis from immuno-modulatory effects we subcutaneously injected these cells, versus control cells, into highly immunocompromised NOD/SCID Il2rγ-/- mice and followed tumor progression. We observed a marked and significant downregulation in the ability of ABCB5-KD cells to maintain efficient tumor growth, implying a direct role for ABCB5 in melanoma progression.

To obtain mechanistic data to explain this phenotype we generated RNA from ABCB5-KD cells versus controls, and performed microarray analysis of global genomic changes in transcript levels of these cells. We then validated potential “ABCB5-pathway” genes, which also change in the reciprocal manner in an ABCB5 overexpression system that we have developed.

Our study links ABCB5 to a direct role in melanoma carcinogenesis, identifies genes and pathways of interest, and uncovers ABCB5 as a putative master-regulator of melanoma.

Citation Format: Brian J. Wilson, Karim R. Saab, Tobias Schatton, Jie Ma, George F. Murphy, Martin Gasser, Ana Maria Waaga-Gasser, Natasha Y. Frank, Markus H. Frank. ABCB5 is functionally required for melanoma growth. [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 243. doi:10.1158/1538-7445.AM2013-243

Abstract 4914: ABCB5 expression in colorectal cancer circulating tumor cells correlates with metastatic disease progression

Targeted personalized treatment approaches are critical for the development of successful therapies for advanced colorectal cancer (CRC). In this regard, circulating tumor cells (CTC) are of foremost interest as potential predictors of metastatic disease progression and patient therapeutic response. We have previously demonstrated that ATP-binding cassette member B5 (ABCB5) is expressed by cancer stem cells (CSC) in several human malignancies, including CRC, and that ABCB5 identifies therapy-refractory tumor subpopulations in CRC patients that correlate with disease progression. In order to evaluate the potential role of ABCB5 as a clinically relevant CTC marker, we utilized a human-to-mouse xenograft model system to examine the relationship of ABCB5-positive CRC-CTC to CRC metastasis. Human CRC tumor cells were grafted subcutaneously into immunocompromized NSG mice. 7 weeks after xenotransplantation, peripheral blood mononuclear cells and lungs were evaluated by qPCR for expression of human ABCB5 and GAPDH mRNAs. Expression analysis of these specimens revealed a significant positive correlation between peripheral blood human ABCB5 mRNA expression and aggregate metastatic disease load as determined by human GAPDH mRNA expression levels in lungs (r=0.8994, P=0.0147). Remarkably, no significant correlation existed between peripheral blood human GAPDH mRNA expression and metastatic disease load, indicating a unique and essential role of ABCB5-positive CSC-CTC in colorectal cancer metastatic disease progression. Significantly increased peripheral blood ABCB5 expression was also observed in a clinical series of UICC stages I-III colorectal cancer patients (n=105) compared to healthy controls (P&lt;0.001). Thus, our results identify the CSC antigen ABCB5 as a novel molecular marker of metastasis-associated CRC-CTC and point to potential utility of ABCB5 as a prognostic indicator and predictor of therapeutic response in patients with advanced colorectal cancer.

Citation Format: Qin Guo, Jie Ma, Brian J. Wilson, Martin Gasser, Ana Maria Waaga-Gasser, Markus H. Frank, Natasha Y. Frank. ABCB5 expression in colorectal cancer circulating tumor cells correlates with metastatic disease 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 4914. doi:10.1158/1538-7445.AM2013-4914