Yusuke Ohara

Histological and prognostic importance of CD44+/CD24+/EpCAM+ expression in clinical pancreatic cancer

CD44+/CD24+/EpCAM+ cells have been reported to be cancer stem cells in pancreatic cancer; however, the histological and clinical importance of these cells has not yet been investigated. Here we clarified the characteristics of CD44+/CD24+/EpCAM+ cells in clinical specimens of pancreatic cancer using immunohistochemical assay. We used surgical specimens of pancreatic ductal adenocarcinoma from 101 patients. In view of tumor heterogeneity, we randomly selected 10 high‐power fields per case, and triple‐positive CD44+/CD24+/EpCAM+ expression was identified using our scoring system. The distribution, histological characteristics, and prognostic importance of CD44+/CD24+/EpCAM+ cells were then analyzed. As a result, the distribution of CD44+/CD24+/EpCAM+ cells varied widely among the 101 cases examined, and CD44+/CD24+/EpCAM+ expression was correlated with poor glandular differentiation and high proliferation. Survival analysis showed that CD44+/CD24+/EpCAM+ expression was not correlated with patient outcome; however, CD44+/CD24+ expression appeared to be correlated with poor prognosis. In conclusion, CD44+/CD24+/EpCAM+ expression overlapped with poorly differentiated cells and possessed high proliferative potential in clinical pancreatic cancer. In particular, the presence of double‐positive CD44+/CD24+ expression seemed to have clinical relevance, associating with poor prognosis.

Anticancer effects of gemcitabine are enhanced by co-administered iRGD peptide in murine pancreatic cancer models that overexpressed neuropilin-1

Background:Impaired drug transport is an important factor that reduces the efficacy of anticancer agents against pancreatic cancer. Here, we report a novel combination chemotherapy using gemcitabine (GEM) and internalised-RGD (iRGD) peptide, which enhances tumour-specific drug penetration by binding neuropilin-1 (NRP1) receptor.Methods:A total of five pancreatic cancer murine models (two cell line-based xenografts (CXs) and three tumour grafts (TGs)) were treated with either GEM (100 mg kg−1, q3d × 4) alone or GEM plus iRGD peptide (8 μmol kg−1). Evaluation of NRP1 expression in xenografts and 48 clinical cancer specimens was performed by immunohistochemistry (IHC).Results:We identified a subset of pancreatic cancer models that showed NRP1 overexpression sensitive to iRGD co-administration. Treatment with GEM plus iRGD peptide resulted in a significant tumour reduction compared with GEM monotherapy in CXs, but not remarkable in TGs. Potential targets of iRGD were characterised as cases showing NRP1 overexpression (IHC-2+/3+), and these accounted for 45.8% of the clinical specimens.Conclusions:Internalised RGD peptide enhances the effects of co-administered drugs in pancreatic cancer models, its efficacy is however only appreciable in those employing cell lines. Therefore, the clinical application needs to be given careful consideration.

Preparation of highly dispersible and tumor-accumulative, iron oxide nanoparticles: Multi-point anchoring of PEG-b-poly(4-vinylbenzylphosphonate) improves performance significantly

This paper describes the preparation of iron oxide nanoparticles, surface of which was coated with extremely high immobilization stability and relatively higher density of poly(ethylene glycol) (PEG), which are referred to as PEG protected iron oxide nanoparticles (PEG-PIONs). The PEG-PIONs were obtained through alkali coprecipitation of iron salts in the presence of the PEG-poly(4-vinylbenzylphosphonate) block copolymer (PEG-b-PVBP). In this system, PEG-b-PVBP served as a surface coating that was bound to the iron oxide surface via multipoint anchoring of the phosphonate groups in the PVBP segment of PEG-b-PVBP. The binding of PEG-b-PVBP onto the iron oxide nanoparticle surface and the subsequent formation of a PEG brush layer were proved by FT-IR, zeta potential, and thermogravimetric measurements. The surface PEG-chain density of the PEG-PIONs varied depending on the [PEG-b-PVBP]/[iron salts] feed-weight ratio in the coprecipitation reaction. PEG-PIONs prepared at an optimal feed-weight ratio in this study showed a high surface PEG-chain surface density (≈0.8 chainsnm(-2)) and small hydrodynamic diameter (<50 nm). Furthermore, these PEG-PIONs could be dispersed in phosphate-buffered saline (PBS) that contains 10% serum without any change in their hydrodynamic diameters over a period of one week, indicating that PEG-PIONs would provide high dispersion stability under in vivo physiological conditions as well as excellent anti-biofouling properties. In fact we have confirmed the prolong blood circulation time and facilitate tumor accumulation (more than 15% IDg(-1) tumor) of PEG-PIONs without the aid of any target ligand in mouse tumor models. The majority of the PEG-PIONs accumulated in the tumor by 96 h after administration, whereas those in normal tissues were smoothly eliminated by 96 h, proving the enhancement of tumor selectivity in the PEG-PION localization. The results obtained here strongly suggest that originally synthesized PEG-b-PVBP, having multipoint anchoring character by the phosphonate groups, is rational design for improvement in nanoparticle as in vivo application. Two major points, viz., extremely stable anchoring character and dense PEG chains tethered on the nanoparticle surface, worked simultaneously to become PEG-PIONs as an ideal biomedical devices intact for prolonged periods in harsh biological environments.

Effective delivery of chemotherapeutic nanoparticles by depleting host Kupffer cells

Although chemotherapeutic nanoparticles would confer various advantages, the majority of administrated nanoparticles are known to be spoiled by the reticuloendothelial system (RES). Intending to more effectively deliver therapeutic nanoparticles to target regions in vivo, host RES, especially Kupffer cells in the liver, have been depleted ahead of drug administration. To demonstrate this hypothesis, clodronate liposomes were preinjected into BALB/c nude mice for depletion of Kupffer cells 2 days before, and pegylated liposomal doxorubicin (Doxil) at the doses of 1.25, 2.5 and 5.0 mg/kg was administered. As a result, doxorubicin accumulation in the liver was decreased from 36 to 26% injected dose/organ by the Kupffer cells depletion, and consequently, the plasma concentration of doxorubicin was significantly enhanced threefold (from 11 to 33 μg/mL) on day 1 at 1.25 mg/kg‐dose group. Doxorubicin accumulation in the tumor was increased from 0.78 to 3.0 μg/g‐tissue on day 3, and tumor growth inhibition by Doxil was significantly boosted (tumor volumes from 751 to 482 mm3 on day 24) by the Kupffer cells depletion. In conclusion, Kupffer cells depletion by clodronate liposomes enhanced the plasma concentration and antitumor effects of Doxil, and would be widely applicable for various clinical cancer chemotherapies using nanoparticles.

Pancreatic neuroendocrine tumor and solid-pseudopapillary neoplasm: Key immunohistochemical profiles for differential diagnosis

AIM To reveal better diagnostic markers for differentiating neuroendocrine tumor (NET) from solid-pseudopapillary neoplasm (SPN), focusing primarily on immunohistochemical analysis. METHODS We reviewed 30 pancreatic surgical specimens of NET (24 cases) and SPN (6 cases). We carried out comprehensive immunohistochemical profiling using 9 markers: Synaptophysin, chromogranin A, pan-cytokeratin, E-cadherin, progesterone receptor, vimentin, α-1-antitrypsin, CD10, and β-catenin. RESULTS E-cadherin staining in NETs, and nuclear labeling of β-catenin in SPNs were the most sensitive and specific markers. Dot-like staining of chromogranin A might indicate the possibility of SPNs rather than NETs. The other six markers were not useful because their expression overlapped widely between NETs and SPNs. Moreover, two cases that had been initially diagnosed as NETs on the basis of their morphological features, demonstrated SPN-like immunohistochemical profiles. Careful diagnosis is crucial as we actually found two confusing cases showing disagreement between the tumor morphology and immunohistochemical profiles. CONCLUSION E-cadherin, chromogranin A, and β-catenin were the most useful markers which should be employed for differentiating between NET and SPN.

Histological advantages of the tumor graft: a murine model involving transplantation of human pancreatic cancer tissue fragments.

Objectives Experimental data based on cell line–derived xenograft models (cell xenograft) seldom reproduce the clinical situation, and therefore we demonstrated here the superiority of a murine model involving transplantation of human pancreatic cancer tissue fragments (tumor graft), focusing on the histological features and drug delivery characteristics. Methods Tumor pieces from 10 pancreatic cancer patients were transplanted into SCID (severe combined immunodeficient) mice. Histological characteristics of tumor grafts, including morphology, desmoplastic reaction, and vascularization, were compared with those of cell xenografts. Drug delivery was evaluated by quantifying the concentrations of injected drug, and the results were compared with its histological features. Results Eight of the 10 transplanted tumors successfully engrafted. Histological comparisons between tumor grafts and cell xenografts revealed the following: the amount of stroma was more (22.9% ± 11.8% vs 10.8% ± 5.4%; P < 0.05), vessel–cancer cell distance was longer (35.3 ± 39.0 vs 3.9 ± 3.1 &mgr;m; P < 0.001), and microvessel density was lower (6.8 ± 1.9 vs 10.8 ± 2.1 vessels/0.4 mm2; P < 0.05) in tumor grafts. Drug concentrations in tumor grafts were lower than those in cell xenografts (3.3 ± 1.2 vs 6.0±0.2 &mgr;g/mL; P = 0.003), and the differences were correlated with the histological differences. Conclusions Pancreatic tumor grafts better reproduce the histological nature of clinical cancer and thus provide a more realistic model that is applicable for pharmacokinetic studies.

Cetuximab delivery and antitumor effects are enhanced by mild hyperthermia in a xenograft mouse model of pancreatic cancer

Even with current promising antitumor antibodies, their antitumor effects on stroma‐rich solid cancers have been insufficient. We used mild hyperthermia with the intent of improving drug delivery by breaking the stromal barrier. Here, we provide preclinical evidence of cetuximab + mild hyperthermia therapy. We used four in vivo pancreatic cancer xenograft mouse models with different stroma amounts (scarce, MIAPaCa‐2; moderate, BxPC‐3; and abundant, Capan‐1 and Ope‐xeno). Cetuximab (1 mg/kg) was given systemically, and the mouse leg tumors were concurrently heated using a water bath method for 30 min at three different temperatures, 25°C (control), 37°C (intra‐abdominal organ level), or 41°C (mild hyperthermia) (n = 4, each group). The evaluated variables were the antitumor effects, represented by tumor volume, and in vivo cetuximab accumulation, indirectly quantified by the immunohistochemical fluorescence intensity value/cell using antibodies against human IgG Fc. At 25°C, the antitumor effects were sufficient, with a cetuximab accumulation value (florescence intensity/cell) of 1632, in the MIAPaCa‐2 model, moderate (1063) in the BxPC‐3 model, and negative in the Capan‐1 and Ope‐xeno models (760, 461). By applying 37°C or 41°C heat, antitumor effects were enhanced shown in decreased tumor volumes. These enhanced effects were accompanied by boosted cetuximab accumulation, which increased by 2.8‐fold (2980, 3015) in the BxPC‐3 model, 2.5‐ or 4.8‐fold (1881, 3615) in the Capan‐1 model, and 3.2‐ or 4.2‐fold (1469, 1922) in the Ope‐xeno model, respectively. Cetuximab was effective in treating even stroma‐rich and k‐ras mutant pancreatic cancer mouse models when the drug delivery was improved by combination with mild hyperthermia.

Platelet × CRP Multiplier Value as an Indicator of Poor Prognosis in Patients With Resectable Pancreatic Cancer

Objective Thrombocytosis in patients with various cancers has been considered a parameter for poor prognosis; however, its contribution to pancreatic cancer remains controversial. Methods Potential preoperative prognostic parameters (platelets, neutrophils, lymphocytes, the platelet-lymphocyte ratio, the neutrophil-lymphocyte ratio, the serum C-reactive protein [CRP], and carbohydrate antigen 19-9) were retrospectively analyzed in 95 patients with pancreatic cancer. Cutoff values were defined according to receiver operating characteristic curve analysis, and median survival times (MSTs) were compared. Results Median survival times (days) significantly differed according to platelet count (high [552] vs low [735], P = 0.017), CRP (high [471] vs low [750], P = 0.001), and carbohydrate antigen 19-9 level (high [639] vs low [765], P = 0.021), whereas there was no difference in the platelet-lymphocyte ratio and the neutrophil-lymphocyte ratio. Multivariate analysis identified thrombocytosis (hazard ratio, 2.015) and CRP level (hazard ratio, 1.771) as independent prognostic factors. The combinatory effects of platelets and the inflammatory response using a platelet × CRP multiplier value could effectively distinguished the MSTs (days) of patients with pancreatic cancer (high [482] vs low [812], P < 0.001). Conclusions Thrombocytosis and CRP influenced pancreatic cancer patient prognosis. Platelet × CRP multiplier is assumed as a useful parameter that reflects the contribution of activated platelets to cancer progression.

Well leg compartment syndrome after surgery for ulcerative colitis in the lithotomy position: A case report

Highlights • Well leg compartment syndrome is rare complication after surgery in the lithotomy position.• Well leg compartment syndrome causes severe neurological and motor dysfunction.• Prolonged operative time in the high lithotomy position is the important risk factor for the development of Well leg compartment syndrome.• Ileoanal pouch procedure have the high potential for occurring well leg compartment syndrome.

Measurement of Intravenously Administered

Dispersions of platelet γ-Fe2O3 particles 30-50nm in size were intravenously administered to mice and the amount of particles accumulated in each tissue was obtained by magnetization measurement using a vibrating sample magnetometer. Background noise was greatly reduced by measuring dried tissues under a magnetic field of 500 Oe so that the effect of diamagnetism was slight. Remarkable particle accumulation was observed in the liver and spleen. Considerable particle accumulation was observed in the lung when a large quantity of γ-Fe2O3 particles was administered. There was no significant particle accumulation in the kidney and heart.