Efficacy of immunochemotherapy as adjuvant treatment after curative resection of gastric cancer. Study Group of Immunochemotherapy with PSK for Gastric Cancer

β-glucan: a potent adjuvant in immunotherapy for digestive tract tumors

The immunotherapy for gastrointestinal tumors, as a significant research direction in the field of oncology treatment in recent years, has garnered extensive attention due to its potential therapeutic efficacy and promising clinical application prospects. Recent advances in immunotherapy notwithstanding, challenges persist, such as side effects, the complexity of the tumor immune microenvironment, variable patient responses, and drug resistance. Consequently, there is a pressing need to explore novel adjunctive therapeutic modalities. β-glucan, an immunomodulatory agent, has exhibited promising anti-tumor efficacy in preclinical studies involving colorectal cancer, pancreatic cancer, and gastric cancer, while also mitigating the adverse reactions associated with chemotherapy and enhancing patients' quality of life. However, further clinical and fundamental research is warranted to comprehensively evaluate its therapeutic potential and underlying biological mechanisms. In the future, β-glucan holds promise as an adjunctive treatment for gastrointestinal tumors, potentially bringing significant benefits to patients.

The Potential Functions and Mechanisms of Oat on Cancer Prevention: A Review

Oat is classified as a whole grain and contains high contents of protein, lipids, carbohydrates, vitamins, minerals, and phytochemicals (such as polyphenols, flavonoids, and saponins). In recent years, studies have focused on the effects of oat consumption on reducing the risk of a variety of diseases. Reports have indicated that an oat diet exerts certain biological functions, such as preventing cardiovascular diseases, reducing blood glucose, and promoting intestinal health, along with antiallergy, antioxidation, and cancer preventive effects. At present, cancer is the second leading cause of death worldwide. The natural products of oat are an important breakthrough for developing new strategies of cancer prevention, and their ability to interact with multiple cellular targets helps to combat the complexity of cancer pathogenesis. In addition, the comprehensive study of the cancer prevention activity and potential mechanism of oat nutrients and phytochemicals has become a research hotspot. In this Review, we focused on the potential functions of peptides, dietary fiber, and phytochemicals in oats on cancer prevention and further revealed novel mechanisms and prospects for clinical application. These findings might provide a novel approach to deeply understand the functions and mechanisms for cancer prevention of oat consumption.

Practical Application of "About Herbs" Website: Herbs and Dietary Supplement Use in Oncology Settings

The Integrative Medicine Service at Memorial Sloan Kettering Cancer Center developed and maintains About Herbs (www.aboutherbs.com), which provides summaries of research data including purported uses, adverse effects, and herb-drug interactions for about 284 dietary supplements. Using Google Analytics, we found the website registered more than 26,317,000 hits since November 2002. The 10 most searched-for herbs/supplements of 2018 are chaga mushroom, turmeric, ashwagandha, reishi mushroom, graviola, Active Hexose-Correlated Compound, boswellia, dandelion, green tea, and Coriolus versicolor. Here we discuss their safety, herb-drug interactions, and appropriate uses in the oncology setting, based on literature searches in PubMed. Over the past 16 years, the evidence for use of these supplements is based mostly on preclinical findings, with few well-designed studies and limited trials conducted in cancer patients. It is important to familiarize health care professionals about popular supplements, so patients can be informed to make decisions that maximize benefits and minimize risks.

Herb-drug interactions between the medicinal mushrooms Lingzhi and Yunzhi and cytotoxic anticancer drugs: a systematic review

BACKGROUND

Lingzhi and Yunzhi are medicinal mushrooms commonly used with cytotoxic chemotherapy in cancer patients in Asian countries. The current systematic review aims to identify potential pharmacokinetic or pharmacodynamic interactions from the existing literature to ensure their effective and safe combination usage in cancer patients.

METHODS

A systematic search was conducted on nine major Chinese and English databases, including China Journal Net, Allied and Complementary Medicine Database, and Ovid MEDLINE®, etc., to identify clinical, animal, and in-vitro studies that evaluate the effect of combined use of Lingzhi or Yunzhi with cytotoxic drugs. The Jadad scale was used to assess the quality of clinical studies.

RESULTS

This search identified 213 studies, including 77 clinical studies that reported on the combined use of cytotoxic drugs with Yunzhi (n = 56) or Lingzhi (n = 21). Majority of these clinical studies demonstrated modest methodological quality. In clinical practice, the most commonly used cytotoxic drugs with Lingzhi were cisplatin, 5-fluorouracil (5-FU) and paclitaxel, whereas Tegafur/uracil (UFT)/Tegafur, 5-FU, and mitomycin were the ones used more often with Yunzhi. Only two clinical pharmacokinetic studies were available showing no significant interactions between Polysaccharide K (PSK) and Tegafur. From the pharmacodynamic interactions perspective, combination uses of Yunzhi/Lingzhi with cytotoxic drugs in clinical practice could lead to improvement in survival (n = 31) and quality of life (n = 17), reduction in tumor lesions (n = 22), immune modulation (n = 38), and alleviation of chemotherapy-related side effects (n = 14) with no reported adverse effects.

CONCLUSION

Our findings suggest that the clinical combination use of Lingzhi or Yunzhi with cytotoxic drugs could enhance the efficacy and ameliorate the adverse effects of cytotoxic drugs, leading to improved quality of life in cancer patients. More high quality clinical studies including pharmacokinetic herb-drug interactions studies are warranted to verify these observations and mechanisms involved. Based on the high quality clinical data, pharmacoepidemiology methods and bioinformatics or data mining could be adopt for further identification of clinical meaningful herb-drug interactions in cancer therapies.

Differential Immune Activating, Anti-Inflammatory, and Regenerative Properties of the Aqueous, Ethanol, and Solid Fractions of a Medicinal Mushroom Blend

Purpose

To compare three fractions of a medicinal mushroom blend (MMB), MyCommunity, on immune-activation, inflammation-regulation, and induction of biomarkers involved in regenerative functions.

Methods

A seventeen-species MMB was sequentially extracted: first, saline solution at ambient temperature, followed by re-extraction of the solids in ethanol, and finally resuspension of the homogenized ethanol-insoluble solids in cell-culture media. Fractions were tested on peripheral blood mononuclear cells from three healthy donors. Immunostaining, flow-cytometry, and Luminex protein-arrays measured immune-cell activation and cytokine response. Dose-responses for induction of the CD69 early activation marker and individual cytokine and growth-factor responses for each donor were evaluated. The CD69 and the combined cytokine and growth-factor results were subjected to Non-metric Multidimensional Scaling (NMDS) and multivariate ordination to aid interpretation of the aggregate immune response and pairwise permutational MANOVA on a distance-matrix to evaluate statistical differences between treatments on pooled data from all donors.

Results

Differential effects were induced by water-soluble, ethanol-soluble, and insoluble immunomodulatory compounds of the MMB. The aqueous and ethanol fractions upregulated expression of CD69 on all tested cell types. Monocyte-activation was correlated with the ethanol fraction, while NKT and non-NK non-T cell-activation was more closely correlated with the aqueous fraction. The solid fraction was the most potent inducer of Tumor Necrosis Factor-α, as well as the anti-viral cytokines interferon-γ, MCP-1 (CCL-2), MIP-1α (CCL-3), and MIP-1β (CCL-4), and induced G-CSF and b-FGF—growth-factors involved in regenerative functions—and the anti-inflammatory cytokine IL-1ra.

Conclusion

The aqueous, ethanol, and insoluble compounds within MMB induced differential immune-activating, anti-inflammatory, and regenerative effects. This in vitro data suggests that, upon consumption, MMB may induce a concerted series of immunomodulatory events based on the differential solubility and bioavailability of the active constituents. These differential responses support both immune-activation and resolution of the host defense-induced inflammatory reactions, thus assisting a post-response return to homeostasis.

Coriolus Versicolor and Ganoderma Lucidum Related Natural Products as an Adjunct Therapy for Cancers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Cancer incidence and mortality rates keep rising globally. Coriolus versicolor and Ganoderma lucidum related natural products are commonly applied as a complementary therapeutic option for different stages and types of cancers. The aim of this study is to evaluate the efficacy and safety of the products for cancer therapy. Methods: Randomized controlled trials were identified by systematic search over seven databases from inceptions to May 10, 2019. Two independent reviewers extracted data and assessed the study quality. Meta-analyses were performed to pool hazard ratio (HR), risk ratio (RR), mean differences (MD), and 95% CI using random-effects models. The sources of heterogeneity were explored by subgroup analyses and sensitivity analyses. Publication bias was detected by Funnel plots, Begg's test, and Egger's test. Results: Twenty-three trials involving 4,246 cancer patients were included in this work. C. versicolor and G. lucidum related natural products were significantly associated with lower risks of mortality (HR: 0.82; 95% CI: 0.72, 0.94) and higher total efficacy (RR: 1.30; 95% CI: 1.09, 1.55), but not associated with control rate (RR: 1.05; 95% CI: 0.96, 1.14) compared with control treatment. There was no significant difference between C. versicolor related natural products and control treatment in the effect on relapse-free survival (HR: 1.19; 95% CI: 0.91, 1.55). Compared with control treatment, C. versicolor and G. lucidum related natural products had a favorable effect on elevated levels of CD3 (MD: 9.03%; 95% CI: 2.10, 16.50) and CD4 (MD: 9.2%; 95% CI: 1.01, 17.39), but had no effect on the levels of CD8 (MD: -5.52%; 95% CI: -23.17, 12.13), CD4/CD8 (MD: 0.73; 95% CI:-0.45, 1.91), or NK(MD: 5.87%; 95% CI: -1.06, 12.8). Conclusion: In this meta-analysis, we found that C. versicolor and G. lucidum related natural products might have potential benefits on the overall survival and quality of life in cancer patients.

Effect on macrophage proliferation of a novel polysaccharide from Lactarius deliciosus (L. ex Fr.) Gray

The fundamental mechanisms underlying the preventional and therapeutic effects of polysaccharides from fungi, including the immunostimulatory, antiviral and antitumor effects, are considered to occur through the modulation and stimulation of the macrophage and complement system. LDG-A, a novel polysaccharide from Lactarius deliciosus (L. ex Fr.) Gray exhibits marked antitumor activities in vivo. However, the underlying molecular mechanism of the antitumor activities of LDG-A remains unclear. In the present study, cell cycle analysis was performed in macrophages and B cells, and the transcriptomes of macrophages in the control group and LDG-A group were sequenced using Illumina sequencing technology to analyze the differentially expressed genes (DEGs), and elucidate the molecular mechanisms underlying the immunomodulatory and antitumor activities of LDG-A. The cell cycle analysis results indicated that LDG-A was able to promote the proliferation of B cells by promoting cell cycle progression in S phase and G2/M phase and eliminating cell cycle arrest in G0/G1, and promote the proliferation of macrophages by promoting cell cycle progression in G0/G1 phase and eliminating cell cycle arrest in G2/M phase. Of the total number of genes (8,140), ~77.00% were expressed [reads per kilobase per million reads (RPKM) ≥1] and 1,352 genes were highly expressed (RPKM >60) in the LDG-A group. Of 775 unigenes which were identified as DEGs, 469 were downregulated and 306 genes were upregulated. A protein chip method was also used to determine the cytokines secreted by macrophages. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis and GO enrichment analysis indicated that the Janus kinase/signal transducer and activator of transcription, mitogen-activated protein kinase, chemokine, vascular endothelial growth factor and transforming growth factor β signaling pathways are markedly enriched for DEGs.

Introduction

This chapter focuses on the discovery of the Major Histocompatibility Complex (MHC) in mice (H-2) and in humans (HLA), and on the role played by the International HLA Workshops in the analysis and characterization of this complex genetic system. The early days of Tumour Immunology and the importance of the definition of Tumour Associated Transplantation Antigens (TATA) are also discussed. Today we know that tumour cells can be killed by T lymphocytes by recognizing tumour antigenic peptides presented by MHC molecules and they can also escape this recognition by losing the expression of MHC molecules. This important phenomenon has been profoundly studied for many years both in my lab in Granada and in other laboratories. The results of this research have important implications for the new generation of cancer immunotherapy that boosts T cell responses. A historical perspective of major discoveries is presented in this chapter, with the names of the scientists that have made a significant contribution to the enormous progress made in the field of Tumour Immunology.

Anti-Cancerous Effect of Inonotus taiwanensis Polysaccharide Extract on Human Acute Monocytic Leukemia Cells through ROS-Independent Intrinsic Mitochondrial Pathway

Acute leukemia is one of the commonly diagnosed neoplasms and causes human death. However, the treatment for acute leukemia is not yet satisfactory. Studies have shown that mushroom-derived polysaccharides display low toxicity and have been used clinically for cancer therapy. Therefore, we set out to evaluate the anti-cancerous efficacy of a water-soluble polysaccharide extract from Inonotus taiwanensis (WSPIS) on human acute monocytic leukemia THP-1 and U937 cell lines in vitro. Under our experimental conditions, WSPIS elicited dose-dependent growth retardation and induced apoptotic cell death. Further analysis showed that WSPIS-induced apoptosis was associated with a mitochondrial apoptotic pathway, such as the disruption of mitochondrial membrane potential (MMP), followed by the activation of caspase-9, caspase-3, and PARP (poly(ADP-ribose) polymerase) cleavage. However, a broad caspase inhibitor, Z-VAD.fmk, could not prevent WSPIS-induced apoptosis. These data imply that mechanism(s) other than caspase might be involved. Thus, the involvement of endonuclease G (endoG), a mediator arbitrating caspase-independent oligonucleosomal DNA fragmentation, was examined. Western blotting demonstrated that WSPIS could elicit nuclear translocation of endoG. MMP disruption after WSPIS treatment was accompanied by intracellular reactive oxygen species (ROS) generation. However, pretreatment with N-acetyl-l-cysteine (NAC) could not attenuate WSPIS-induced apoptosis. In addition, our data also show that WSPIS could inhibit autophagy. Activation of autophagy by rapamycin decreased WSPIS-induced apoptosis and cell death. Taken together, our findings suggest that cell cycle arrest, endonuclease G-mediated apoptosis, and autophagy inhibition contribute to the anti-cancerous effect of WSPIS on human acute monocytic leukemia cells.

Randomized phase III trial comparing surgery alone to UFT + PSK for stage II rectal cancer (JFMC38 trial)

Background

We conducted a randomized phase III trial comparing tegafur/uracil (UFT) and Polysaccharide-K (PSK) to surgery alone in curatively resected stage II rectal cancer patients.

Methods

Patients were randomly assigned to receive either UFT and PSK or surgery alone in a 1:1 ratio with a minimization method to balance the treatment allocation. The primary end point of this study was the disease-free survival (DFS). The secondary end point was the overall survival (OS).

Results

From October 2011 to February 2013, 111 patients were registered from 62 institutions. The study was prematurely closed due to poor accrual after reaching 20% of its goal. The patients’ characteristics were similar between the UFT and PSK group and the surgery-alone group. The DFS rate was 76.0% at 3 years and 65.1% at 5 years in the UFT and PSK arm and 84.0% at 3 years and 77.2% at 5 years in the surgery-alone arm. The DFS was slightly worse in the UFT + PSK arm than in the surgery-alone arm, but the difference did not reach statistical significance (log rank p = 0.102). The OS rate was 100% at 3 years and 97.9% at 5 years in the UFT + PSK arm, while that was 100% at 3 years and 93.4% at 5 years in the surgery-alone arm. The OS was similar in the UFT + PSK arm and surgery-alone arm (p = 0.533).

Conclusion

The present study suggests that UFT and PSK are not attractive candidates to advance to the next phase III study because the DFS was slightly worse in the UFT and PSK arm than in the surgery-alone arm.

Can polysaccharide K improve therapeutic efficacy and safety in gastrointestinal cancer? a systematic review and network meta-analysis

Objective

To assess the comparative efficacy and safety of polysaccharide K (PSK), with or without chemotherapy, for patients with gastrointestinal cancer (GIC) through a systematic review and network meta-analysis.

Materials and Methods

We performed a network meta-analysis to identify evidence from randomized controlled trials. We searched PubMed, Embase and the Cochrane Library for publications up to May 2017. The prespecified primary efficacy outcomes were 1–7 year overall survival (OS), while the secondary efficacy outcomes were 1–7 year disease-free survival (DFS); we performed subgroup analyses and meta-regressions according to the cancer type (colorectal, esophagus and gastric cancer) and treatment arms (with or without chemotherapy). Safety outcomes were side effects of PSK. We conducted pairwise meta-analyses using a random-effects model and then performed random-effects network meta-analyses.

Results

A total of 23 trials were eligible, involving 10684 patients and 13 intervention arms. PSK treatment significantly increased 1–5 year OS and resulted in positive trends in 6–7 year OS; significant increases were also found in 1–7 year DFS, while no increase in side effects was observed. Significant efficacy outcomes obvious in colorectal and gastric cancer groups, as well as PSK combined with chemotherapy groups (iv, po, iv+po). Network meta-analysis revealed that PSK combined with chemotherapy was superior, with significantly increased 3-year and 5-year OS. The study is registered with PROSPERO (CRD42017065193)

Conclusions

The adjuvant immunochemotherapy agent PSK is effective and safe for patients with GIC. PSK combined with chemotherapy appears to be the preferred application of PSK.

Immunochemotherapy benefits in gastric cancer patients stratified by programmed death-1 ligand-1

BACKGROUND

Effectiveness of protein-bound polysaccharide K (PSK) during adjuvant chemotherapy in gastric cancer patients expressing programmed death-1 ligand 1 (PD-L1) has not been investigated. Investigating this might help in triaging candidates eligible to immunochemotherapy.

MATERIALS AND METHODS

In total, 918 patients with stages II and III gastric cancer, undergoing curative gastrectomy, and receiving adjuvant chemotherapy were enrolled in a prospective database, and the patients were retrospectively reviewed. We classified those patients into four cohorts stratified by PD-L1 expression and PSK administration, namely PD-L1, PSK (-,+); PD-L1, PSK (-,-); PD-L1, PSK (+,+); and PD-L1, PSK (+,-). In addition, another independent cohort of 20 patients undergoing radical gastrectomy was prospectively recruited to check their immunological cells of sera before and 2 mo after PSK administration.

RESULTS

PSK treatment was an independent prognostic factor for patient's overall survival (P = 0.020), whereas PD-L1 expression per se was not. Administration of PSK prolonged patient survival in stages IIIA and IIIB (P = 0.031) but not in stage II or stage IIIC. Patients with negative expression of PD-L1, treated with PSK had longer survival than those not treated with PSK (P = 0.033). PSK did not affect the survival of patients with positive expression of PD-L1, (P = 0.421). The percentages of natural killer and natural killer T (NKT) cells, but not Th1, Th17, Treg, or IFN-γ+/CD8+ T cells, were significantly increased in PD-L1 (-) patients treated with PSK. However, these findings were not evident in PD-L1 (+) patients.

CONCLUSIONS

PSK treatment preferentially confers a survival gain for patients with stage IIIA/IIIB gastric cancer, especially in the PD-L1 (-) subpopulation.

Structure elucidation, proliferation effect on macrophage and its mechanism of a new heteropolysaccharide from Lactarius deliciosus Gray

A new heteropolysaccharide was isolated from the fruiting bodies of Lactarius deliciosus Gray which had a molecular weight of 16kDa and was mainly composed of the galactose and glucose. Structural elucidation results indicated that Lactarius deliciosus Gray polysaccharide (LDG-B) had a backbone of (1,6)-linked d-galactose and (1, 2, 6)-linked d-galactose which branches were mainly composed of 4-linked d-glucose and 6-linked d-galactose residue. Cell cycle test results showed that LDG-B could promote the proliferation of B cells and macrophage cells by affecting G0/G1 phase, S phases and G2/M phases. The analysis of transcriptomes sequence of macrophages showed a total of 1839 genes were identified as DEGs, and approximately 708 genes were up-regulated, whereas 1131 genes were down-regulated in LDG-B group. KEGG pathway enrichment analysis showed that the MAPK, JAK-STAT and NF-κB signaling pathways are significantly enriched for DEGs in LDG-B group. Analysis of transcriptome resources enabled us to examine gene expression profiles, verify differential gene expression, and select candidate signaling pathways as the mechanisms of the immunomodulatory activity of LDG-B.

Comparative analysis of macrophage transcriptomes reveals a key mechanism of the immunomodulatory activity of Tricholoma matsutake polysaccharide

In the present study, we performed a proliferation assay, phagocytosis assay and cell cycle analysis of macrophages and sequenced the transcriptomes of control group macrophages and TMP-A group macrophages using Illumina sequencing technology to identify differentially expressed genes (DEGs) and determine the molecular mechanisms associated with differences in the immunomodulatory activity of TMP-A in macrophages. The results showed that TMP-A exhibits strong proliferation activity and phagocytosis activity in RAW264.7 cells in vitro and could also promote the proliferation of macrophage cells by abolishing cell-cycle arrest in the G0/G1 phase and promoting the cell cycle in the G2/M phase, which may induce cell division. A total of 12,616,096 and 11,798,839 bp paired-end reads were obtained for the control group and TMP-A group, respectively, and they corresponded to a total size of 12.5 G bp and 11.7 G bp, respectively, after the low-quality reads and adapter sequences were removed. Approximately 79.8% of the total number of genes (10,191) were expressed (RPKM ≥1), and more than 1,372 genes were highly expressed (RPKM >60) in the TMP-A group. A total of 1,043 unigenes were identified as DEGs, and approximately 486 genes were upregulated, whereas 557 genes were down-regulated, which might have contributed to the proliferation activity and phagocytosis activity of TMP-A in the RAW264.7 cells in vitro. A Gene Ontology (GO) enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functions. A KEGG pathway enrichment analysis showed that the MAPK and NF-κB signaling pathways are significantly enriched for DEGs between the two cell groups. Based on the experimental data, we believe that the significant antitumor activities of TMP-A in vivo involve the MAPK and NF-κB signaling pathways because the two signaling pathways intersect.

Evolving treatments for advanced gastric cancer: appraisal of the survival trend

Introduction and areas covered: We analysed the results of the main clinical studies looking at patients with advanced gastric or esophagogastric junction cancer, in order to differentiate between what is already clinical evidence and what is a promise for the cure of such patients. Thus, achievements from key studies, which had been purposely directed at chemotherapy, molecular target therapies and immunotherapy in both first and second-line setting were analysed. Metronomic chemotherapy, which consists of the administration of continuative low-dose anticancer drugs, was considered also. Expert commentary: It was found that patients included in experimental arms of randomized trials compared with controls have often benefited from a statistically significant extension of overall survival. However, further studies are awaited to bring new drugs into clinical practice and to validate candidate biomarkers predictive of response.

Leccinum vulpinum Watling induces DNA damage, decreases cell proliferation and induces apoptosis on the human MCF-7 breast cancer cell line

The current work aimed to study the antitumour activity of a phenolic extract of the edible mushroom Leccinum vulpinum Watling, rich essentially in hydroxybenzoic acids. In a first approach, the mushroom extract was tested against cancer cell growth by using four human tumour cell lines. Given the positive results obtained in these initial screening experiments and the evidence of some studies for an inverse relationship between mushroom consumption and breast cancer risk, a detailed study of the bioactivity of the extract was carried out on MCF-7 cells. Once the selected cell line to precede the work was the breast adenocarcinoma cell line, the human breast non-malignant cell line MCF-10A was used as control. Overall, the extract decreased cellular proliferation and induced apoptosis. Furthermore, the results also suggest that the extract causes cellular DNA damage. Data obtained highlight the potential of mushrooms as a source of biologically active compounds, particularly with antitumour activity.

Immunotherapy for advanced gastric and esophageal cancer: preclinical rationale and ongoing clinical investigations

Gastric and esophageal cancers represent a major global cancer burden and novel approaches are needed. Despite recent improvements in outcomes with trastuzumab and ramucirumab the prognosis for advanced disease remains poor, with a median overall survival of 1 year. Comprehensive genomic characterization has defined molecular subgroups and potentially actionable genomic alterations, but the majority of patients do not yet benefit from molecularly directed therapies. Breakthroughs in immune checkpoint blockade have provided new therapeutic avenues in melanoma, and continue to expand into other tumor types, with ongoing investigations in gastrointestinal (GI) malignancies. The frequency of programmed death ligand 1 (PD-L1) overexpression, a putative response biomarker, approaches forty percent in gastric cancers. Translational studies and molecular classification suggest gastric and esophageal cancers are candidate malignancies for immune checkpoint inhibition trials and early clinical data is promising. Here we review the mechanisms, preclinical, and early clinical data supporting the role for immune checkpoint blockade in gastric and esophageal cancer.

Clinical efficacy of protein-bound polysaccharide K in patients with gastric cancer undergoing chemotherapy with an oral fluoropyrimidine (S-1)

BACKGROUND

The aim of the present study was to evaluate the clinical significance of protein-bound polysaccharide K (PSK) in patients with primary gastric cancer who were being treated with an oral fluoropyrimidine (S-1).

METHODS

Clinical reports of 190 gastric cancer patients treated with S-1 chemotherapy, with or without PSK, at Kochi Medical School between 2007 and 2012 were investigated retrospectively to analyze survival. The neutrophil:lymphocyte ratio (NLR) was also evaluated as indicator of the immunoenhancing effect of PSK.

RESULTS

Overall survival was significantly longer in patients treated with S-1 + PSK than in those given S-1 alone (hazard ratio for death, 0.608; 95% confidence interval 0.375-0.985; P = 0.041). Furthermore, there was a tendency for changes in the NLR during chemotherapy to be lower in the S-1 + PSK group than in the S-1 group, but the difference did not reach statistical significance (P = 0.054). When patients were divided into groups based on preoperative NLR (i.e. <2.5 and ≥2.5), the mean (±SEM) NLR 1 month after the beginning of chemotherapy in the NLR ≥2.5 subgroup was significantly lower in patients treated with S-1 + PSK rather than S-1 alone (1.7 ± 0.7 vs. 3.3 ± 4.1, respectively; P = 0.043).

CONCLUSIONS

Immunochemotherapy using PSK improves the survival of patients with advanced gastric cancer. The NLR may be a useful biomarker for evaluating prognosis in these patients.

Inhibitory effect of polysaccharide peptide (PSP) against Tobacco mosaic virus (TMV)

Polysaccharides are essential macromolecules present in all living organisms, and have many kinds of biological activities, such as anti-oxidation, hypoglycemic, enhancing immunity, anti-aging, anti-rheumatism, anti-cancer and so on. In this study, the antiviral activity of polysaccharide peptide (PSP) was tested, compared with Ningnanmycin, and firstly found it has a stronger antiviral activity by using half-leaf method and leaf disk method. Subsequently, the mechanism of antiviral activity of PSP was preliminarily studied. As a result, its antiviral effect was better than the commercial agent Ningnanmycin, despite of protective effect, curative effect and inactivation effect. On the other hand, PSP as a commercial anti-cancer drug could easily and rapidly get in large quantities by liquid fermentation, which makes the industrialized production feasible. Also PSP is less toxic, easily biodegradable and ecofriendly. All the results are suggesting that PSP has potential as a pesticide to be used for the control of plant virus in the future.

Preoperative administration of polysaccharide Kureha and reduced plasma transforming growth factor-β in patients with advanced gastric cancer: A randomized clinical trial

Systemic abrogation of TGF-β signaling results in tumor reduction through cytotoxic T lymphocytes activity in a mouse model. The administration of polysaccharide-Kureha (PSK) into tumor-bearing mice also showed tumor regression with reduced TGF-β. However, there have been no studies regarding the PSK administration to cancer patients and the association with plasma TGF-β. PSK (3 g/day) was administered as a neoadjuvant therapy for 2 weeks before surgery. In total, 31 advanced gastric cancer (AGC) patients were randomly assigned to group A (no neoadjuvant PSK; n=14) or B (neoadjuvant PSK therapy; n=17). Plasma TGF-β was measured pre- and postoperatively. The allocation factors were clinical stage (cStage) and gender. Plasma TGF-β ranged from 1.85-43.5 ng/ml (average, 9.50 ng/ml) in AGC, and 12 patients (38.7%) had a high value, >7.0 ng/ml. These patients were largely composed of poorly-differentiated adenocarcinoma with pathological stage III/IV. All the six elevated cases in group B showed a significant reduction of plasma TGF-β (from 21.6 to 4.5 ng/ml, on average), whereas this was not exhibited in group A. The cases within the normal limits of TGF-β remained unchanged irrespective of PSK treatment. Analysis of variance showed a statistically significant reduction in the difference of plasma TGF-β between groups A and B (P=0.019). PSK reduced the plasma TGF-β in AGC patients when the levels were initially high. The clinical advantage of PSK may, however, be restricted to specific histological types of AGC. Perioperative suppression of TGF-β by PSK may antagonize cancer immune evasion and improve patient prognosis in cases of AGC.

The TLR2 agonist in polysaccharide-K is a structurally distinct lipid which acts synergistically with the protein-bound β-glucan

Protein-bound polysaccharide-K (Krestin; PSK) is a hot-water extract of Trametes versicolor with immune stimulatory activity. It has been used for the past 30 years and has demonstrated anti-tumor efficacy in multiple types of cancer. The ability of PSK to activate dendritic cells and T cells is dependent on its ability to stimulate Toll-like receptor 2 (TLR2), yet it remains unknown which structural component within PSK activates TLR2. The purpose of this study was to identify the TLR2 agonist within PSK and understand its role in the overall mechanism of PSK's immunogenic activity. TLR2 activity was eliminated by treatment with lipoprotein lipase but not by trypsin or lyticase. Rapid centrifugation of PSK can separate the fraction with TLR2 agonist activity from the soluble β-glucan fraction. To study the potential interaction between the β-glucan component and the lipid component, we labeled the soluble β-glucan with fluorescein. Uptake of the labeled β-glucan by J774A macrophages and JAWSII dendritic cells was inhibited by anti-Dectin-1 antibody but not by anti-TLR2 antibody, confirming that Dectin-1 is the receptor for β-glucan. Interestingly, pre-treatment of JAWSII cells with the TLR2-active lipid fraction significantly enhanced the uptake of the soluble β-glucan, indicating the synergy between the TLR2 agonist component and the β-glucan component. Altogether, these results present evidence that PSK has two active components-the well-characterized protein-bound β-glucan and a previously unreported lipid-which work synergistically via the Dectin-1 and TLR2 receptors.

Anti-GD2 antibody 3F8 and barley-derived (1 → 3),(1 → 4)-β-D-glucan: A Phase I study in patients with chemoresistant neuroblastoma

β-glucans are complex, naturally-occurring polysaccharides that prime leukocyte dectin and complement receptor 3. Based on our preclinical findings, indicating that oral barley-derived (1 → 3),(1 → 4)-β-D-glucan (BG) synergizes with the murine anti-GD2 antibody 3F8 against neuroblastoma, we conducted a Phase I clinical study to evaluate the safety of this combinatorial regimen in patients affected by chemoresistant neuroblastoma. In this setting, four cohorts of six heavily pre-treated patients bearing recurrent or refractory advanced-stage neuroblastoma were treated with 3F8 plus BG. Each cycle consisted of intravenous 3F8 at a fixed dose of 10 mg/m²/day plus concurrent oral BG, dose-escalated from 10 to 80 mg/Kg/day, for 10 d. Patients who did not develop human anti-mouse antibodies could be treated for up to 4 cycles. Twenty-four patients completed 50 cycles of therapy. All patients completed at least one cycle and were evaluable for the assessment of toxicity and responses. The maximum tolerated dose of BG was not reached, but two patients developed dose-limiting toxicities. These individuals developed grade 4 thrombocytopenia after one cycle of BG at doses of 20 mg/Kg/day and 40 mg/Kg/day, respectively. Platelet counts recovered following the administration of idiopathic thrombocytopenic purpura therapy. There were no other toxicities of grade > 2. Eleven and 13 patients manifested stable and progressive disease, respectively. Thirteen out of 22 patients with pre-treatment positive ¹²³I-MIBG scans demonstrated clinical improvement on semiquantitative scoring. Responses did not correlate with BG dose or with in vitro cytotoxicity. In summary, 3F8 plus BG is well tolerated and shows antineoplastic activity in recurrent or refractory advanced-stage neuroblastoma patients. Further clinical investigation of this novel combinatorial immunotherapeutic regimen is warranted.

Immunomodulation of Fungal β-Glucan in Host Defense Signaling by Dectin-1

During the course of evolution, animals encountered the harmful effects of fungi, which are strong pathogens. Therefore, they have developed powerful mechanisms to protect themselves against these fungal invaders. β-Glucans are glucose polymers of a linear β(1,3)-glucan backbone with β(1,6)-linked side chains. The immunostimulatory and antitumor activities of β-glucans have been reported; however, their mechanisms have only begun to be elucidated. Fungal and particulate β-glucans, despite their large size, can be taken up by the M cells of Peyer's patches, and interact with macrophages or dendritic cells (DCs) and activate systemic immune responses to overcome the fungal infection. The sampled β-glucans function as pathogen-associated molecular patterns (PAMPs) and are recognized by pattern recognition receptors (PRRs) on innate immune cells. Dectin-1 receptor systems have been incorporated as the PRRs of β-glucans in the innate immune cells of higher animal systems, which function on the front line against fungal infection, and have been exploited in cancer treatments to enhance systemic immune function. Dectin-1 on macrophages and DCs performs dual functions: internalization of β-glucan-containing particles and transmittance of its signals into the nucleus. This review will depict in detail how the physicochemical nature of β-glucan contributes to its immunostimulating effect in hosts and the potential uses of β-glucan by elucidating the dectin-1 signal transduction pathway. The elucidation of β-glucan and its signaling pathway will undoubtedly open a new research area on its potential therapeutic applications, including as immunostimulants for antifungal and anti-cancer regimens.

Cloning and Molecular Characterization of β-1,3-Glucan Synthase from Sparassis crispa

A β-glucan synthase gene was isolated from the genomic DNA of polypore mushroom Sparassis crispa, which reportedly produces unusually high amount of soluble β-1,3-glucan (β-glucan). Sequencing and subsequent open reading frame analysis of the isolated gene revealed that the gene (5,502 bp) consisted of 10 exons separated by nine introns. The predicted mRNA encoded a β-glucan synthase protein, consisting of 1,576 amino acid residues. Comparison of the predicted protein sequence with multiple fungal β-glucan synthases estimated that the isolated gene contained a complete N-terminus but was lacking approximately 70 amino acid residues in the C-terminus. Fungal β-glucan synthases are integral membrane proteins, containing the two catalytic and two transmembrane domains. The lacking C-terminal part of S. crispa β-glucan synthase was estimated to include catalytically insignificant transmembrane α-helices and loops. Sequence analysis of 101 fungal β-glucan synthases, obtained from public databases, revealed that the β-glucan synthases with various fungal origins were categorized into corresponding fungal groups in the classification system. Interestingly, mushrooms belonging to the class Agaricomycetes were found to contain two distinct types (Type I and II) of β-glucan synthases with the type-specific sequence signatures in the loop regions. S. crispa β-glucan synthase in this study belonged to Type II family, meaning Type I β-glucan synthase is expected to be discovered in S. crispa. The high productivity of soluble β-glucan was not explained but detailed biochemical studies on the catalytic loop domain in the S. crispa β-glucan synthase will provide better explanations.

A novel polysaccharide from Ganoderma atrum exerts antitumor activity by activating mitochondria-mediated apoptotic pathway and boosting the immune system

Ganoderma is a precious health-care edible medicinal fungus in China. A novel Ganoderma atrum polysaccharide (PSG-1) is the main bioactive component. We investigated the antitumor effect and molecular mechanisms of PSG-1. It exhibited no significant effect on cell proliferation directly. In contrast, administration of PSG-1 markedly suppressed tumor growth in CT26 tumor-bearing mice. It was observed that PSG-1 caused apoptosis in CT26 cells. Apoptosis was associated with loss of mitochondrial membrane potential, enhancement of mitochondrial cytochrome c release and intracellular ROS production, elevation of p53 and Bax expression, downregulation of Bcl-2, and the activation of caspase-9 and -3. Moreover, PSG-1 enhanced immune organ index and promoted lymphocyte proliferation as well as cytokine levels in serum. Taken together, our data indicate that PSG-1 has potential antitumor activity in vivo by inducing apoptosis via mitochondria-mediated apoptotic pathway and enhances host immune system function. Therefore, PSG-1 could be a safe and effective antitumor, bioactive agent or functional food.

Crude dietary polysaccharide fraction isolated from jackfruit enhances immune system activity in mice

Crude polysaccharides (PSs) were isolated from the fruit pulp of jackfruit, and their chemical composition determined and evaluated for an immune regulatory activity in mice. The PSs were isolated from water extracts of jackfruit pulp (JFP) using the ethanol precipitation method. The resulting precipitates were further purified by dialysis and protein depletion by the Sevage method. The phenol-sulfuric method was used to determine the content of the PSs. The composition of PSs was determined by the Sephadex-G200 column chromatography and high-performance liquid chromatography methods. The thymus index and macrophage phagocytic function methods in mice were used to evaluate the immune regulatory activity of JFP-PSs. The JFP-PSs content in jackfruit was about 21% (w/w) and the yield of crude PSs was 3.91%. The single molecular mass weight PS was the main constituent of JFP-PSs. The major monosaccharide residues were rhamnose, glucose, galactose, and arabinose. The JFP-PSs enhanced the thymus weight index and the phagocytic rate after 30 days of subchronic p.o. administration to mice at 4.5 mg/kg. The JFP contains single molecular PS and JFP-PS has immune-stimulating activities in mice. These data suggest that at least some of the traditional uses of JFP can be ascribed to its immunomodulatory effects.

The use of lentinan for treating gastric cancer

Natural compounds containing fungal β-glucans have been used to improve general health for thousands of years in China and Japan. Lentinan, the backbone of β-(1, 3)-glucan with β-(1, 6) branches, is one of the active ingredients purified from Shiitake mushrooms and has been approved as a biological response modifier for the treatment of gastric cancer in Japan. Despite recent advances in chemotherapeutic agents, unresectable or recurrent gastric cancer remains an incurable disease, with survival rates being far from satisfactory. Recent clinical studies have shown that chemo-immunotherapy using lentinan prolongs the survival of patients with advanced gastric cancer, as compared to chemotherapy alone. In addition, trastuzumab, an antibody against HER2/neu growth factor receptor, has been used for the treatment of gastric cancer in combination with cytotoxic chemotherapeutic agents. Lentinan may exert a synergistic action with anti-cancer monoclonal antibodies to activate complement systems through the mechanism of antibody-dependent cellular cytotoxicity and complement dependent cytotoxicity. Because a better understanding of its biological activities should enable us to use lentinan more efficiently in the treatment of gastric cancer, immunological effects provided by β-glucans, a possible mode of action of lentinan, and its clinical application including future potential uses are discussed in the present review.

Solitary rib recurrence of hilar cholangiocarcinoma 10 years after resection: report of a case

A 61-year-old female underwent right hemihepatectomy and caudate lobectomy for hilar cholangiocarcinoma in 1999. Ten years later, increasing serum carbohydrate 19-9 was detected by routine follow-up. Subsequent positron emission tomography revealed an asymptomatic lesion in the right 11th rib. As the mass steadily grew in size, the lesion was resected en bloc with the affected rib and muscle. The histopathological findings closely resembled those of the primary cholangiocarcinoma. Thus, the tumor was diagnosed as a metastatic recurrence 10 years after resection of the primary tumor. There have been a few reports of cholangiocarcinoma recurrence in long-term survivors at the surgical margins, peritoneum, or transhepatic drainage route. However, there are no reports of solitary extra-abdominal recurrence. This case highlights the need for careful follow-up of patients with cholangiocarcinoma and nodal metastasis, even in the absence of recurrence for >5 years after curative resection.

Strategies to improve the immunogenicity of anticancer vaccines based on dendritic cell/malignant cell fusions

The rationale for fusing dendritic cells (DCs) with whole tumor cells to generate anticancer vaccines resides in the fact that the former operate as potent antigen-presenting cells, whereas the latter express a constellation of tumor-associated antigens (TAAs). Although the administration of DC/malignant cell fusions to cancer patients is safe and this immunotherapeutic intervention triggers efficient tumor-specific T-cell responses in vitro, a limited number of objective clinical responses to DC/cancer cell fusions has been reported thus far. This review discusses novel approaches to improve the immunogenicity of DC/malignant cell fusions as anticancer vaccines.

Protein-bound polysaccharide-K induces apoptosis via mitochondria and p38 mitogen-activated protein kinase-dependent pathways in HL-60 promyelomonocytic leukemia cells

Protein-bound polysaccharide-K (PSK) is extracted from Coriolus versicolor (CM101). PSK is a biological response modifier (BRM), and its mechanism of action is partly mediated by modulating host immune systems; however, recent studies showed antiproliferative activity of PSK. Therefore, we examined the mechanism underlying the antiproliferative activity of PSK using seven different human malignant cell lines (WiDr, HT29, SW480, KATOIII, AGS, HL-60 and U937), and PSK was found to inhibit the proliferation of HL-60 cells most profoundly. Therefore, HL-60 cells were used to elucidate the mechanism of the antiproliferative activity. Western blotting was performed to detect phosphorylated p38 mitogen-activated protein kinase (MAPK). A p38 MAPK inhibitor, SB203580, was used to examine the roles in PSK-induced apoptosis and growth inhibition. Flow cytometry was performed for mitochondrial membrane potential detection. PSK activated caspase-3 and induced p38 MAPK phosphorylation. Co-treatment with SB203580 blocked PSK-induced apoptosis, caspase-3 activation and growth inhibition. PSK induced apoptosis via the mitochondrial pathway. The depolarization of mitochondria induced by PSK was reversed by co-treatment with SB203580. The present study revealed that PSK induced apoptosis in HL-60 cells via a mitochondrial and p38 MAPK-dependent pathway.

Augmentation of antitumor immunity by fusions of ethanol-treated tumor cells and dendritic cells stimulated via dual TLRs through TGF-β1 blockade and IL-12p70 production

The therapeutic efficacy of fusion cell (FC)-based cancer vaccine generated with whole tumor cells and dendritic cells (DCs) requires the improved immunogenicity of both cells. Treatment of whole tumor cells with ethanol resulted in blockade of immune-suppressive soluble factors such as transforming growth factor (TGF)-β1, vascular endothelial growth factor, and IL-10 without decreased expression of major histocompatibility complex (MHC) class I and the MUC1 tumor-associated antigen. Moreover, the ethanol-treated tumor cells expressed “eat-me” signals such as calreticulin (CRT) on the cell surface and released immunostimulatory factors such as heat shock protein (HSP)90α and high-mobility group box 1 (HMGB1). A dual stimulation of protein-bound polysaccharides isolated from Coriolus versicolor (TLR2 agonist) and penicillin-inactivated Streptococcus pyogenes (TLR4 agonist) led human monocyte-derived DCs to produce HSP90α and multiple cytokines such as IL-12p70 and IL-10. Interestingly, incorporating ethanol-treated tumor cells and TLRs-stimulated DCs during the fusion process promoted fusion efficiency and up-regulated MHC class II molecules on a per fusion basis. Moreover, fusions of ethanol-treated tumor cells and dual TLRs-stimulated DCs (E-tumor/FCs) inhibited the production of multiple immune-suppressive soluble factors including TGF-β1 and up-regulated the production of IL-12p70 and HSP90α. Most importantly, E-tumor/FCs activated T cells capable of producing high levels of IFN-γ, resulting in augmented MUC1-specific CTL induction. Collectively, our results illustrate the synergy between ethanol-treated whole tumor cells and dual TLRs-stimulated DCs in inducing augmented CTL responses in vitro by FC preparations. The alternative system is simple and may provide a platform for adoptive immunotherapy.

Combined TLR2/4-activated dendritic/tumor cell fusions induce augmented cytotoxic T lymphocytes

Induction of antitumor immunity by dendritic cell (DC)-tumor fusion cells (DC/tumor) can be modulated by their activation status. In this study, to address optimal status of DC/tumor to induce efficient antigen-specific cytotoxic T lymphocytes (CTLs), we have created various types of DC/tumor: 1) un-activated DC/tumor; 2) penicillin-killed Streptococcus pyogenes (OK-432; TLR4 agonist)-activated DC/tumor; 3) protein-bound polysaccharides isolated from Coriolus versicolor (PSK; TLR2 agonist)-activated DC/tumor; and 4) Combined OK-432- and PSK-activated DC/tumor. Moreover, we assessed the effects of TGF-β1 derived from DC/tumor on the induction of MUC1-specific CTLs. Combined TLR2- and TLR4-activated DC/tumor overcame immune-suppressive effect of TGF-β1 in comparison to those single activated or un-activated DC/tumor as demonstrated by: 1) up-regulation of MHC class II and CD86 expression on DC/tumor; 2) increased fusion efficiency; 3) increased production of fusions derived IL-12p70; 4) activation of CD4⁺ and CD8⁺ T cells that produce high levels of IFN-γ; 5) augmented induction of CTL activity specific for MUC1; and 6) superior efficacy in inhibiting CD4⁺CD25⁺Foxp3⁺ T cell generation. However, DC/tumor-derived TGF-β1 reduced the efficacy of DC/tumor vaccine in vitro. Incorporating combined TLRs-activation and TGF-β1-blockade of DC/tumor may enhance the effectiveness of DC/tumor-based cancer vaccines and have the potential applicability to the field of adoptive immunotherapy.

Efficacy of adjuvant immunotherapy with cytokine-induced killer cells in patients with locally advanced gastric cancer

Purpose

To determine the long-term efficacy of adjuvant immunotherapy with autologous cytokine-induced killer (CIK) cells for locally advanced gastric cancer patients.

Experimental design

One hundred and fifty-one patients with stage III/IV gastric cancer who had undergone gastrectomy were enrolled, assigned to two groups (immunotherapy group versus no immunotherapy group/or control group), and followed.

Results

The 5-year overall survival (OS) and 5-year disease-free survival (DFS) rates for immunotherapy versus control group were 32.4 versus 23.4 % (P = 0.071) and 28.3 versus 10.4 % (P = 0.044), respectively. For patients with intestinal-type tumors, the 5-year OS and DFS rates were significantly higher for immunotherapy (OS, 46.8 vs. 31.4 % and P = 0.045; DFS, 42.4 vs. 15.7 % and P = 0.023). In the immunotherapy group, the mean CD3⁺ level, CD4⁺ level, and CD4⁺/CD8⁺ ratio increased from 50.8, 26.5, and 0.9 %, respectively, at baseline to 62.6, 35.0, and 1.4 %, respectively, 1 week after the first CIK-cell treatment, returned to baseline after 2 months, and maintained a higher level (60.7 ± 8.2 %, 34.2 ± 7.1 %, and 1.3 ± 0.3 %, respectively) 2 months after 3 cycles of immunotherapy.

Conclusions

Adjuvant immunotherapy with CIK cells prolongs DFS in patients with locally advanced gastric cancer and significantly improves OS in patients with intestinal-type tumors. Intestinal-type tumors could be selected as an important indication for CIK-cell therapy. This treatment may help improve T-lymphocyte subset distribution and improve the host’s immune functions, but multiple cycles are necessary for long-term therapeutic efficacy.

Correlation between efficacy of PSK postoperative adjuvant immunochemotherapy for gastric cancer and expression of MHC class I

Protein-bound polysaccharide K (PSK) is a glycoprotein that is purified from the mushroom Coriolus versicolor. In Japan, PSK is clinically used in combination with anticancer agents following gastric cancer surgery. Evaluation of the response is difficult, as efficacy is determined via antitumor immunoenhancing effects, and for that reason PSK has not become a standard therapy. The present study evaluated the expression of MHC class I in gastric cancer patients who received PSK postoperative adjuvant immunochemotherapy, and investigated the correlation between MHC class I expression and clinical outcomes. The subjects comprised 349 patients with stage II/III gastric cancer, who had received adjuvant therapy following curative resection between 1995 and 2008. MHC class I expression in the primary lesion was evaluated by immunohistochemical staining. Patients were divided into two treatment groups: one was only administered oral chemotherapy (chemotherapy-only group) and the other was administered chemotherapy plus PSK (PSK group). The clinical outcomes were compared between the two groups. The two groups did not differ in regard to their MHC class I expression. Expression-negative cases demonstrated 3-year recurrence-free survival (RFS) rates of 65% in the PSK group and 47% in the chemotherapy-only group. Therefore, the PSK group revealed a prolonged survival. For the 82 expression-negative cases with pN2 or greater, the RFS rates were 68% in the PSK group and 28% in the chemotherapy-only group, representing a significant difference. Thus, PSK adjuvant immunochemotherapy may be effective in MHC class I-negative patients, who are in a state of antitumor immunological tolerance, and patients with advanced lymph node metastasis of pN2 or greater.

Differences in sensitivity to tumor-specific CTLs between primary and metastatic esophageal cancer cell lines derived from the same patient

PURPOSE

MHC antigens and adhesion molecules, such as the intracellular adhesion molecule (ICAM-I), play an important role in cellular immune response. We examined the expression patterns of these molecules in both primary and metastatic esophageal carcinoma cells from the same patient and evaluated the cellular immune responses against these cells.

MATERIALS AND METHODS

In the esophageal cancer patient (H122), tumor cell lines were established from primary and subcutaneous metastatic lesions. We compared the expression of cell surface molecules on the metastatic tumor cell line (H122SC) with that on the primary tumor cell line (H122ESO) using flow cytometry. Moreover, we analyzed the differences in cellular immune responses against these cell lines, which expressed similar levels of the Tara antigen, using the Tara antigen-specific CTL clone.

RESULTS

H122SC ICAM-1 expression was significantly lower in H122ESO, and the Tara antigen-specific CTL clone produced lower levels of TNF in response to H122SC than H122ESO. ICAM-1 transfection into the H122SC rendered these cells as sensitive to the CTL clone as the H122ESO.

CONCLUSION

The metastatic tumor cells displayed lower regulated ICAM-1 expression levels and were less sensitive to specific CTLs. ICAM-1 downregulation may be one mechanism by which tumor cells escape immunologic surveillance.

Biological mechanism and clinical effect of protein-bound polysaccharide K (KRESTIN(®)): review of development and future perspectives

The mechanism of action of protein-bound polysaccharide K (PSK; KRESTIN(®)) involves the following actions: (1) recovery from immunosuppression induced by humoral factors such as transforming growth factor (TGF)-β or as a result of surgery and chemotherapy; (2) activation of antitumor immune responses including maturation of dendritic cells, correction of Th1/Th2 imbalance, and promotion of interleukin-15 production by monocytes; and (3) enhancement of the antitumor effect of chemotherapy by induction of apoptosis and inhibition of metastasis through direct actions on tumor cells. The clinical effectiveness of PSK has been demonstrated for various cancers. In patients with gastric or colorectal cancer, combined use of PSK with postoperative adjuvant chemotherapy prolongs survival, and this effect has been confirmed in multiple meta-analyses. For small-cell lung carcinoma, PSK in conjunction with chemotherapy prolongs the remission period. In addition, PSK has been shown to be effective against various other cancers, reduce the adverse effects of chemotherapy, and improve quality of life. Future studies should examine the effects of PSK under different host immune conditions and tumor properties, elucidate the mechanism of action exhibited in each situation, and identify biomarkers.

Polysaccharide-K (PSK) may suppress surgical stress-induced metastasis in rat colon cancer

PURPOSE

We previously demonstrated that hepatic ischemia and reperfusion (I/R) injury increased liver metastasis and cancer growth of RCN-H4 cells. Using a rat model of hepatic I/R-induced liver metastasis, we investigated the metastasis-suppressing effect of polysaccharide-K (PSK), a biological response modifier composed of protein-bound polysaccharide.

METHODS

Fischer rats underwent 60 min of 70% partial hepatic ischemia. After 60 min of reperfusion, rat colon adenocarcinoma cells (RCN-H4) were inoculated intrasplenically. PSK was administered orally before I/R, after I/R, or before and after I/R. The weights of metastatic lesions of the liver or the numbers of liver metastatic nodules were determined on day 21. The effect of PSK on angiogenesis was studied by a rat cornea model using RCN-H4 cells or a vascular endothelial growth factor (VEGF)-containing pellet and an in vitro VEGF-induced endothelial cell migration assay.

RESULTS

PSK administration significantly (p < 0.05) suppressed the I/R-induced increase in hepatic metastasis of RCN-H4 cells. The suppression of I/R-promoted metastasis was observed irrespective of the timing of administration. Furthermore, PSK significantly suppressed angiogenesis induced by RCN-H4 cells (p < 0.05) and the VEGF pellet (p < 0.01). PSK significantly suppressed the VEGF-induced migration of vascular endothelial cells (p < 0.05).

CONCLUSION

PSK may suppress metastasis induced by hepatic I/R. The suppression of angiogenesis by PSK may be one of the mechanisms of the inhibition of hepatic metastasis.

Polysaccharide-K augments docetaxel-induced tumor suppression and antitumor immune response in an immunocompetent murine model of human prostate cancer

Advanced castration-resistant prostate cancer has high mortality rates and limited treatment options. Novel therapies are needed to better contend with this disease. Polysaccharide-K^® (PSK), an extract of the mushroom Trametes versicolor, has immunomodulatory and tumor suppressive activities. PSK is used in Asia as a cancer immunotherapy. However, its benefit in combination with taxanes for prostate cancer is unknown. We examined whether PSK would enhance docetaxel-induced apoptosis and augment anti-tumor immune responses in orthotopic tumors using transgenic adenocarcinoma of the mouse prostate (TRAMP)-C2-bearing mice. Combining PSK with docetaxel induced significantly higher tumor suppression than either treatment alone (p<0.05), including a reduction in tumor proliferation and enhanced apoptosis. Combined PSK and docetaxel treatment led to a lower decrease in number of white blood cells than docetaxel alone, an effect accompanied by increased numbers of tumor-infiltrating CD4⁺ and CD8⁺ T cells. PSK with or without docetaxel significantly enhanced mRNA expression of IFN-γ compared to control, but did not significantly alter T-regulatory FoxP3 mRNA expression in tumors. PSK also augmented docetaxel-induced splenic natural killer cell cytolytic activity against YAC-1 target cells (p=0.045). This study is the first to show that PSK enhances docetaxel-induced prostate cancer tumor suppression, apoptosis and antitumor responses.

Direct inhibition of the transforming growth factor-β pathway by protein-bound polysaccharide through inactivation of Smad2 signaling

Transforming growth factor-β (TGF-β) is involved in the regulation of cell proliferation, differentiation, and apoptosis and is associated with epithelial-mesenchymal transition (EMT). Inhibition of the TGF-β pathway is an attractive strategy for the treatment of cancer. We recently screened for novel TGF-β inhibitors among commercially available drugs and identified protein-bound polysaccharide (PSK) as a strong inhibitor of the TGF-β-induced reporter activity of 3TP-lux, a TGF-β1-responsive luciferase reporter. Protein-bound polysaccharide is used as a non-specific immunostimulant for the treatment of gastric and colorectal cancers in Japan. The anticancer activity of this agent may involve direct regulation of growth factor production and enzyme activity in tumors in addition to its immunomodulatory effect. Although several clinical studies have shown the beneficial therapeutic effects of PSK on various types of tumors, its mechanism of action is not clear. In the present study, Western blot analysis showed that PSK suppressed the phosphorylation and nuclear localization of the Smad2 protein, thereby suggesting that PSK inhibits the Smad and MAPK pathways. Quantitative PCR analysis showed that PSK decreased the expression of several TGF-β pathway target genes. E-cadherin and vimentin immunohistochemistry showed that PSK suppressed TGF-β1-induced EMT, and FACS analysis showed that PSK inhibited the EMT-mediated generation of CD44(+) /CD24(-) cells. These data provide new insights into the mechanisms mediating the TGF-β-inhibiting activity of PSK and suggest that PSK can effectively treat diseases associated with TGF-β signaling.

Acute and subchronic oral toxicity of Coriolus versicolor standardized water extract in Sprague-Dawley rats

ETHNOPHARMACOLOGICAL RELEVANCE

Coriolus versicolor, which is known as Yun Zhi, is one of the commonly used Chinese medicinal herbs. Recent studies have demonstrated its antitumor activities on cancer cells which led to its widespread use in cancer patient. However, little toxicological information is available regarding its safety. The present study evaluated the potential toxicity of Coriolus versicolor standardized water extract after acute and subchronic administration in rats.

MATERIALS AND METHODS

In acute toxicity study, Coriolus versicolor water extract was administered by oral gavage to Sprague-Dawley (SD) rats (6 males, 6 females) at single doses of varying concentrations 1250, 2500 and 5000 mg/kg. In subchronic toxicity study, the extract was administered orally at doses of 1250, 2500 and 5000 mg/kg/day for 28 days to male and female SD rats respectively. General behavior, adverse effects and mortality were determined throughout the experimental period. Haematological and biochemical parameters, relative organ weights and histopathological were evaluated at the end of the experiment.

RESULTS

There were no mortality and signs of toxicity in acute and subchronic toxicity studies. In the single dose acute toxicity and repeated dose 28-day subchronic toxicity studies, there were no significant difference in body weight, relative organ weight, haematological parameters, clinical chemistry, gross pathology and histopathology between treatment and control groups.

CONCLUSIONS

Coriolus versicolor water extract did not cause remarkable adverse effect in SD rats. The oral lethal dose of Coriolus versicolor water extract is more than 5000 mg/kg and no-observed-adverse-effect level (NOAEL) of the extract for both male and female rats is 5000 mg/kg per day for 28 days.

Lentinan prolonged survival in patients with gastric cancer receiving S-1-based chemotherapy

AIM: To examine whether administration of lentinan, purified β-1, 3-glucan, can prolong survival in advanced gastric cancer patients receiving S-1-based chemotherapy.

METHODS: Since 2004, 78 patients with metastatic or recurrent gastric cancer have received S-1-based chemotherapy as first-line treatment. Survival, side effects, and the ratio of granulocytes/lymphocytes (G/L ratio) were compared between 2 groups of patients who received chemo-immunotherapy using lentinan and chemotherapy alone.

RESULTS: Median overall survival was significantly longer in the former group than in the latter group [689 d (95% CI: 431-2339 d) vs 565 d (95% CI: 323-662 d), P = 0.0406]. In addition, the G/L ratio in patients who received lentinan was maintained around or below 2, which was significantly lower than that in patients who received chemotherapy alone (P < 0.001).

CONCLUSION: Chemo-immunotherapy with lentinan offers a significant advantage over S-1-based chemotherapy alone in terms of survival in patients with advanced gastric cancer.

TLR2 agonist PSK activates human NK cells and enhances the antitumor effect of HER2-targeted monoclonal antibody therapy

PURPOSE

The therapeutic effect of trastuzumab monoclonal antibody (mAb) therapy has been shown to be partially dependent on functional natural killer (NK) cells. Novel agents that enhance NK cell function could potentially improve the antitumor effect of trastuzumab. We recently identified polysaccharide krestin (PSK), a natural product extracted from medicinal mushroom Trametes versicolor, as a potent toll-like receptor 2 (TLR2) agonist. This study was undertaken to evaluate the effect of PSK on human NK cells and the potential of using PSK to enhance HER2-targeted mAb therapy.

EXPERIMENTAL DESIGN

Human peripheral blood mononuclear cells were stimulated with PSK to evaluate the effect of PSK on NK cell activation, IFN-γ production, cytotoxicity, and trastuzumab-mediated antibody-dependent cell-mediated cytotoxicity (ADCC). Whether the effect of PSK on NK cells is direct or indirect was also investigated. Then, in vivo experiment in neu transgenic (neu-T) mice was carried out to determine the potential of using PSK to augment the antitumor effect of HER2-targeted mAb therapy.

RESULTS

PSK activated human NK cells to produce IFN-γ and to lyse K562 target cells. PSK also enhanced trastuzumab-mediated ADCC against SKBR3 and MDA-MB-231 breast cancer cells. Both direct and interleukin-12-dependent indirect effects seem to be involved in the effect of PSK on NK cells. Oral administration of PSK significantly potentiated the antitumor effect of anti-HER2/neu mAb therapy in neu-T mice.

CONCLUSION

These results showed that PSK activates human NK cells and potentiates trastuzumab-mediated ADCC. Concurrent treatment with PSK and trastuzumab may be a novel way to augment the antitumor effect of trastuzumab.

Immunotherapy eradicates metastases with reversible defects in MHC class I expression

Tumor or metastatic cells lose MHC class I (MHC-I) expression during cancer progression as an escape mechanism from immune surveillance. These defects in MHC-I may be reversible by cytokines or different agents (soft lesions) or irreversible due to structural defects (hard lesions). The nature of these MHC-I alterations might determine the success or failure of immunotherapy treatments. In this study, we have used an MHC-I-positive murine fibrosarcoma tumor clone, GR9-A7, which generates multiple lung and lymph node metastases with reversible MHC-I alterations after treatment with IFN-γ. Four different antitumor treatments were carried out after primary tumor excision to determine their capacity to inhibit spontaneous metastatic colonization of the GR9-A7 tumor clone. We found that 2 different immunotherapy protocols (CpG plus autologous irradiated-GR9-A7 cells and protein-bound polysaccharide K (PSK) and 1 chemoimmunotherapy (docetaxel plus PSK) induced eradication of metastases. In contrast, chemotherapy with docetaxel alone produced only partial reduction in the number of metastases. Flow cytometric analysis of lymphocyte populations showed an immunosuppression in GR9-A7 tumor-bearing host, which could be reverted by immunotherapy treatments. Our results suggest that irreversible or reversible MHC-I alterations in tumor target cells may determine its progression or regression independently of the type of immunotherapy used.

Helicobacter pylori infection as an independent prognostic factor for locally advanced gastric cancer patients treated with adjuvant chemotherapy after curative resection

A few studies reported the association between negative Helicobacter pylori infection and poor clinical outcome in resected gastric cancer patients. We investigated the H. pylori infection status and its association with the clinical outcome in 274 locally advanced gastric cancer patients (American Joint Committee on Cancer stage IB: 25, II: 82, IIIA: 80, IIIB: 39 and IV: 48) who underwent adjuvant chemotherapy after curative resection (≥ D2 dissection). H. pylori infection status in hematoxylin and eosin stained corporal and antral mucosa of non-tumor tissue was graded according to the updated Sydney System and categorized as H. pylori negative (normal or mild infection) and H. pylori positive (moderate or marked infection). Eighty-one patients received 5-fluorouracil (5-FU) and doxorubicin-based chemotherapy, while 193 patients underwent 5-FU, mitomycin-C and polysaccharide-K chemotherapy. The median follow-up duration of survivors was 144 (120-184) months. In univariate analysis, patients with H. pylori negative status (108 patients) demonstrated significantly poor 10-year overall survival (OS) compared to those with H. pylori-positive status (166 patients; 21.3% vs. 71.1%, p < 0.0001). H. pylori negative status was associated with poor outcome in all stages except stage IIIB. In multivariate analysis, H. pylori-negative status was the most significant independent prognostic factor of poor OS (hazard ratio: 3.45, 95% confidence interval: 2.43-4.89, p < 0.0001) followed by old age (>54 years, p < 0.0001), advanced stage (stage III or IV, p = 0.001), and Borrmann type IV (p = 0.027). H. pylori infection status seems to have strong prognostic significance in locally advanced gastric cancer. H. pylori-negative patients may need careful follow-up after curative resection.