Activity of acute pancreatitis is modified by secreted protein acidic and rich in cysteine ablation

Background

Acute pancreatitis (AP) is a frequent cause for hospitalization. However, molecular determinants that modulate severity of experimental pancreatitis are only partially understood.

Objective

To investigate the role of secreted protein acidic and rich in cysteine (SPARC) during cerulein‐induced AP in mice.

Methods

AP was induced by repeated cerulein injections in SPARC knock‐out mice (SPARC^−/−) and control littermates (SPARC^+/+). Secreted protein acidic and rich in cysteine expression and severity of AP were determined by histopathological scoring, immunohistochemistry, and biochemical assays. For functional analysis, primary murine acinar cell cultures with subsequent amylase release assays were employed. Proteome profiler assay and ELISA were conducted from pancreatic tissue lysates, and co‐immunofluorescence was performed.

Results

Upon cerulein induction, SPARC expression was robustly induced in pancreatic stellate cells (PSCs) but not in acinar cells. Genetic SPARC ablation resulted in attenuated severity of AP with significantly reduced levels of pancreatic necrosis, apoptosis, immune cell infiltration, and reduced fibrosis upon chronic stimulation. However, the release of amylase upon cerulein stimulation in primary acinar cell culture from SPARC^+/+ and SPARC^−/− was indistinguishable. Notably, immune cell derived C‐C Motif Chemokine Ligand 2 (CCL2) was highly elevated in SPARC^+/+ pancreatic tissue potentially linking PSC derived SPARC with CCL2 induction in AP.

Conclusion

SPARC mediates the severity of AP. The potential link between SPARC and the CCL2 axis could open new avenues for tailored therapeutic interventions in AP patients and warrants further investigations.

Depletion of Macrophages Improves Therapeutic Response to Gemcitabine in Murine Pancreas Cancer

BACKGROUND

The tumor microenvironment (TME) is composed of fibro-inflammatory cells and extracellular matrix (ECM) components. However, the exact contribution of the various TME compartments towards therapeutic response is unknown. Here, we aim to dissect the specific contribution of tumor-associated macrophages (TAMs) towards drug delivery and response in pancreatic ductal adenocarcinoma (PDAC).

METHODS

The effect of gemcitabine was assessed in human and murine macrophages, human pancreatic stellate cells (hPSCs), and tumor cells (L3.6pl, BxPC3 and KPC) in vitro. The drug metabolism of gemcitabine was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Preclinical studies were conducted using KrasG12D;p48-Cre and KrasG12D;p53172H;Pdx-Cre mice to investigate gemcitabine delivery at different stages of tumor progression and upon pharmacological TAM depletion.

RESULTS

Gemcitabine accumulation was significantly increased in murine PDAC tissue compared to pancreatic intraepithelial neoplasia (PanIN) lesions and healthy control pancreas tissue. In vitro, macrophages accumulated and rapidly metabolized gemcitabine resulting in a significant drug scavenging effect for gemcitabine. Finally, pharmacological TAM depletion enhanced therapeutic response to gemcitabine in tumor-bearing KPC mice.

CONCLUSION

Macrophages rapidly metabolize gemcitabine in vitro, and pharmacological depletion improves the therapeutic response to gemcitabine in vivo. Our study supports the notion that TAMs might be a promising therapeutic target in PDAC.

SPARC dependent collagen deposition and gemcitabine delivery in a genetically engineered mouse model of pancreas cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterised by extensive matrix deposition that has been implicated in impaired drug delivery and therapeutic resistance. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that regulates collagen deposition and is highly upregulated in the activated stroma subtype with poor prognosis in PDAC patients.

METHODS

KrasG12D;p48-Cre;SPARC-/- (KC-SPARC-/-) and KrasG12D;p48-Cre;SPARCWT (KC-SPARCWT) were generated and analysed at different stages of carcinogenesis by histological grading, immunohistochemistry for epithelial and stromal markers, survival and preclinical analysis. Pharmacokinetic and pharmacodynamic studies were conducted by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunohistochemistry following gemcitabine treatment (100 mg/kg) in vivo.

FINDINGS

Global genetic ablation of SPARC in a KrasG12D driven mouse model resulted in significantly reduced overall and mature collagen deposition around early and advanced pancreatic intraepithelial neoplasia (PanIN) lesions and in invasive PDAC (p < .001). However, detailed pathological scoring and molecular analysis showed no effects on PanIN to PDAC progression, vessel density (CD31), tumour incidence, grading or metastatic frequency. Despite comparable tumour kinetics, ablation of SPARC resulted in a significantly shortened survival in KC-SPARC-/- mice (280 days versus 485 days, p < .03, log-rank-test). Using LC-MS/MS, we show that SPARC dependent collagen deposition does not affect intratumoural gemcitabine accumulation or immediate therapeutic response in tumour bearing KC-SPARCWT and KC-SPARC-/-mice.

INTERPRETATION

Global SPARC ablation reduces the collagen-rich microenvironment in murine PDAC. Moreover, global SPARC depletion did not affect tumour growth kinetics, grading or metastatic frequency. Notably, the dense-collagen matrix did not restrict access of gemcitabine to the tumour. These findings may have direct translational implications in clinical trial design.

Prospective comparison of 2D-shearwave elastography in both liver lobes in healthy subjects and in patients with chronic liver disease

Background/aims: 2D-shearwave elastography is an established method for liver stiffness measurement (LSM). However, the success rate of LSM using the recommended standard technique in the right lobe is limited by several factors. We aimed to compare LSM in the right and left liver lobe in order to evaluate whether LSM in the left lobe could be an alternative if measurements in the right lobe are not feasible. Methods: A total of 116 subjects, 58 healthy volunteers and 58 patients with chronic liver disease (CLD), were prospectively included. LSM were performed in the right lobe and in the left lobe, both in neutral and in inspiration position. Results: LSM in the left lobe (8.39(±4.83)kPa) was significantly (p < .001) higher than LSM in the right lobe (6.27(±2.45)kPa). LSM in inspiration position (8.60(±4.33) kPa) was significantly (p = .009) higher than LSM in neutral position (7.70(±3.01)kPa). LSM in the left lobe overestimated the grade of fibrosis in 50.0% of the patients with CLD. However, correlation between LSM values right and left was strong (r = 0.856) and additional use of LSM in the left lobe increased the success rate from 106/116 (91.4%) to 112/116 (96.6%; p = .098). High skin-to-liver-capsule-distance and presence of ascites were independent risk factors for non-successful LSM. Conclusions: Despite significantly higher values, LSM in the left lobe may be an alternative if LSM in the right lobe is not feasible, and cirrhosis can be ruled out with high probability if LSM is within the normal range.

Preclinical Evaluation of 1,2-Diamino-4,5-Dibromobenzene in Genetically Engineered Mouse Models of Pancreatic Cancer

Background: Pancreatic ductal adenocarcinoma (PDAC) is highly resistant to standard chemo- and radiotherapy. Recently, a new class of non-platinum-based halogenated molecules (called FMD compounds) was discovered that selectively kills cancer cells. Here, we investigate the potential of 1,2-Diamino-4,5-dibromobenzene (2Br-DAB) in combination with standard chemotherapy and radiotherapy in murine and human PDAC. Methods: Cell viability and colony formation was performed in human (Panc1, BxPC3, PaTu8988t, MiaPaCa) and three murine LSL-Kras^G12D/+;LSL-Trp53^R172H/+;Pdx-1-Cre (KPC) pancreatic cancer cell lines. In vivo, preclinical experiments were conducted in LSL-Kras^G12D/+;p48-Cre (KC) and KPC mice using 2Br-DAB (7 mg/kg, i.p.), +/- radiation (10 × 1.8 Gy), gemcitabine (100 mg/kg, i.p.), or a combination. Tumor growth and therapeutic response were assessed by high-resolution ultrasound and immunohistochemistry. Results: 2Br-DAB significantly reduced cell viability in human and murine pancreatic cancer cell lines in a dose-dependent manner. In particular, colony formation in human Panc1 cells was significantly decreased upon 25 µM 2Br-DAB + radiation treatment compared with vehicle control (p = 0.03). In vivo, 2Br-DAB reduced tumor frequency in KC mice. In the KPC model, 2Br-DAB or gemcitabine monotherapy had comparable therapeutic effects. Furthermore, the combination of gemcitabine and 2Br-DAB or 2Br-DAB and 18 Gy irradiation showed additional antineoplastic effects. Conclusions: 2Br-DAB is effective in killing pancreatic cancer cells in vitro. 2Br-DAB was not toxic in vivo, and additional antineoplastic effects were observed in combination with irradiation.

Evaluation of liver stiffness by 2D-SWE in combination with non-invasive parameters as predictors for esophageal varices in patients with advanced chronic liver disease

Background/aims: Esophageal varices (EV) are common complications in patients with advanced chronic liver disease (ACLD). Non-invasive parameters to exclude EV in patients with ACLD would be desirable. The aim of this study was the evaluation of liver stiffness measurement (LSM) using 2D-shear wave elastography (GE Logiq E9) and other non-invasive parameters as predictors for EV. Methods: Hundred patients with ACLD were enrolled. Abdominal sonography, including measurement of gall bladder wall thickness (GBWT), spleen diameter and LSM, gastroscopy and blood test results were evaluated. Statistical analyses were performed for the association between EV and non-invasive parameters. Results: Fifty-one per cent of the patients had EV. The mean LSM (14.6 kPa) and GBWT (3.88 mm) in the group with EV were significantly higher than in the group without EV (10.6 kPa; 2.94 mm; p < .01). Performing area under the receiver operating characteristic curve, LSM has a better diagnostic performance (0.781) than GBWT (0.707), spleen diameter (0.672) and platelet count (0.635). Combining LSM (cut-off 13.58 kPa) and GBWT (cut-off 3.07 mm) resulted in a sensitivity of 86.3% and a specificity of 71.4% for the presence of EV. A sensitivity of 100% (negative predictive value 1.0) was achieved at LSM >9 kPa or GBWT >4 mm. Following these criteria in our current study population, 18% of the gastroscopies could have been avoided. Conclusions: Combining LSM with non-invasive parameters, especially GBWT, improves the diagnostic accuracy for predicting EV. We suggest reconsidering screening gastroscopy in patients with ACLD who show LSM <9 kPa and GBWT <4 mm due to the very low risk of having varices.

Cytosolic 5'-nucleotidase 1A is overexpressed in pancreatic cancer and mediates gemcitabine resistance by reducing intracellular gemcitabine metabolites

BACKGROUND

Cytosolic 5'-nucleotidase 1A (NT5C1A) dephosphorylates non-cyclic nucleoside monophosphates to produce nucleosides and inorganic phosphates. Here, we investigate NT5C1A expression in pancreatic ductal adenocarcinoma (PDAC) and its impact on gemcitabine metabolism and therapeutic efficacy.

METHODS

NT5C1A expression was determined by semiquantitative immunohistochemistry using tissue microarrays. Gemcitabine metabolites and response were assessed in several human and murine PDAC cell lines using crystal violet assays, Western blot, viability assays, and liquid chromatography tandem mass-spectrometry (LC-MS/MS).

FINDINGS

NT5C1A was strongly expressed in tumor cells of a large subgroup of resected PDAC patients in two independent patient cohorts (44-56% score 2 and 8-26% score 3, n = 414). In contrast, NT5C1A was expressed at very low levels in the tumor stroma, and neither stromal nor tumoral expression was a prognostic marker for postoperative survival. In vitro, NT5C1A overexpression increased gemcitabine resistance by reducing apoptosis levels and significantly decreased intracellular amounts of cytotoxic dFdCTP in +NT5C1A tumor cells. Co-culture experiments with conditioned media from +NT5C1A PSCs improved gemcitabine efficacy in tumor cells. In vivo, therapeutic efficacy of gemcitabine was significantly decreased and serum levels of the inactive gemcitabine metabolite dFdU significantly increased in mice bearing NT5C1A overexpressing tumors.

INTERPRETATION

NT5C1A is robustly expressed in tumor cells of resected PDAC patients. Moreover, NT5C1A mediates gemcitabine resistance by decreasing the amount of intracellular dFdCTP, leading to reduced tumor cell apoptosis and larger pancreatic tumors in mice. Further studies should clarify the role of NT5C1A as novel predictor for gemcitabine treatment response in patients with PDAC.

A putatively functional haplotype in the gene encoding transforming growth factor beta-1 as a potential biomarker for radiosensitivity

PURPOSE

To determine whether genetic variability in TGFB1 is related to circulating transforming growth factor-β1 (TGF-β1) plasma concentrations after radiotherapy and to radiosensitivity of lymphoid cells.

PATIENTS AND METHODS

Transforming growth factor-β1 plasma concentrations (n=79) were measured in patients 1 year after radiotherapy and chromosomal aberrations (n=71) ex vivo before therapy start. Furthermore, TGF-β1 secretion and apoptosis were measured in isolated peripheral blood mononuclear cells of 55 healthy volunteers. These phenotypes were analyzed in relation to five germline polymorphisms in the 5' region of the TGFB1 gene. Because of high linkage disequilibrium, these five polymorphisms reflect frequent genetic variation in this region. A presumed impact of TGF-β1 on DNA damage or repair was measured as micronucleus formation in 30 lymphoblastoid cell lines.

RESULTS

We identified a hypofunctional genetic haplotype termed H3 tagging the 5' region of the TGFB1 gene encoding TGF-β1. H3 was associated with lower TGF-β1 plasma concentrations in patients (p=0.01) and reduced TGF-β1 secretion in irradiated peripheral blood mononuclear cells (p=0.003). Furthermore, cells with H3 were less prone to induction of chromosomal aberrations (p=0.001) and apoptosis (p=0.003) by irradiation. The hypothesis that high TGF-β1 could sensitize cells to DNA damage was further supported by increased micronuclei formation in 30 lymphoblastoid cell lines when preincubated with TGF-β1 before irradiation (p=0.04).

CONCLUSIONS

On the basis of TGF-β1 plasma levels and radiation sensitivity of lymphoid cells, this study revealed a putatively hypofunctional TGFB1 haplotype. The significance of this haplotype and the suggested link between TGF-β1 function and DNA integrity should be further explored in other cell types, as well as other experimental and clinical conditions.