The evolution of cancer genomic medicine in Japan and the role of the National Cancer Center Japan

The journey to implement cancer genomic medicine(CGM)in oncology practice began in the 1980s,which is considered the dawn of genetic and genomic cancer research.At the time,a variety of activating oncogenic alterations and their functional significance were unveiled in cancer cells,which led to the development of molecular targeted therapies in the 2000s and beyond.Although CGM is still a relatively new discipline and it is difficult to predict to what extent CGM will benefit the diverse pool of cancer patients,the National Cancer Center(NCC)of Japan has already contributed considerably to CGM advancement for the conquest of cancer.Looking back at these past achievements of the NCC,we predict that the future of CGM will involve the following:1)A biobank of paired cancerous and non-cancerous tissues and cells from various cancer types and stages will be developed.The quantity and quality of these samples will be compatible with omics analyses.All biobank samples will be linked to longitudinal clinical information.2)New technologies,such as whole-genome sequencing and artificial intelligence,will be introduced and new bioresources for functional and pharmacologic analyses(e.g.,a patient-derived xenograft library)will be systematically deployed.3)Fast and bidirectional translational research(bench-to-bedside and bedside-to-bench)performed by basic researchers and clinical investigators,preferably working alongside each other at the same institution,will be implemented;4)Close collaborations between academia,industry,regulatory bodies,and funding agencies will be established.5)There will be an investment in the other branch of CGM,personalized preventive medicine,based on the individual's genetic predisposition to cancer.

Application of patient-derived tumor models in anticancer drug development and individualized medicine

Malignant tumor is the second leading cause of death due to its high incidence, lack of effective treatment and poor prognosis. The evaluation of anticancer drugs used to based on NCI-60 cell line models, but the limited heterogeneity and the divorce from clinical practice of models lead to extremely low success rate of novel anticancer drugs during clinical trials (less than 10%). In recent years, because of the high heterogeneity and human derived tumor matrix, patient-derived tumor models have been gradually applied to the preclinical evaluation of various antitumor drugs, which shows certain advantages in predicting the clinical efficacy of antitumor drugs. Optimize the drug combination through patient-derived tumor models to achieve individualized medicine has gradually become an indispensable strategy in clinical cancer therapy. The current review summarized the development of patient-derived tumor models, characterized the application, advantages and challenges of them in preclinical antitumor drug evaluation and clinical precise medicine, which will provide a scientific basis and novel insights for further basic research, drug development and clinical application.

First report on establishment and characterization of the extrahepatic cholangiocarcinoma sarcoma cell line CBC2T-2

BACKGROUND Extrahepatic cholangiocarcinoma sarcoma is extremely rare in clinical practice.These cells consist of both epithelial and mesenchymal cells.Patient-derived cell lines that maintain tumor characteristics are valuable tools for studying the molecular mechanisms associated with carcinosarcoma.However,cholangiocarcinoma sarcoma cell lines are not available in cell banks.AIM To establish and characterize a new extrahepatic cholangiocarcinoma sarcoma cell line,namely CBC2T-2.METHODS We conducted a short tandem repeat(STR)test to confirm the identity of the CBC2T-2 cell line.Furthermore,we assessed the migratory and invasive properties of the cells and performed clonogenicity assay to evaluate the ability of individual cells to form colonies.The tumorigenic potential of CBC2T-2 cells was tested in vivo using nonobese diabetic/severe combined immunodeficient(NOD/SCID)mice.The cells were injected subcutaneously and tumor formation was observed.In addition,immunohistochemical analysis was carried out to examine the expression of epithelial marker CK19 and mesenchymal marker vimentin in both CBC2T-2 cells and xenografts.The CBC2T-2 cell line was used to screen the potential therapeutic effects of various clinical agents in patients with cholangiocarcinoma sarcoma.Lastly,whole-exome sequencing was performed to identify genetic alterations and screen for somatic mutations in the CBC2T-2 cell line.RESULTS The STR test showed that there was no cross-contamination and the results were identical to those of the original tissue.The cells showed round or oval-shaped epithelioid cells and mesenchymal cells with spindle-shaped or elongated morphology.The cells exhibited a high proliferation ratio with a doubling time of 47.11 h.This cell line has migratory,invasive,and clonogenic abilities.The chromosomes in the CBC2T-2 cells were polyploidy,with numbers ranging from 69 to 79.The subcutaneous tumorigenic assay confirmed the in vivo tumorigenic ability of CBC2T-2 cells in NOD/SCID mice.CBC2T-2 cells and xenografts were positive for both the epithelial marker,CK19,and the mesenchymal marker,vimentin.These results suggest that CBC2T-2 cells may have both epithelial and mesenchymal characteristics.The cells were also used to screen clinical agents in patients with cholangiocarcinoma sarcoma,and a combination of paclitaxel and gemcitabine was found to be the most effective treatment option.CONCLUSION We established the first human cholangiocarcinoma sarcoma cell line,CBC2T-2,with stable biogenetic traits.This cell line,as a research model,has a high clinical value and would facilitate the understanding of the pathogenesis of cholangiocarcinoma sarcoma.

A biomimetic nanoplatform for customized photothermal therapy of HNSCC evaluated on patient-derived xenograft models

Cancer cell membrane(CCM)derived nanotechnology functionalizes nanoparticles(NPs)to recognize homologous cells,exhibiting translational potential in accurate tumor therapy.However,these nanoplatforms are majorly generated from fixed cell lines and are typically evaluated in cell line-derived subcutaneous-xenografts(CDX),ignoring the tumor heterogeneity and differentiation from inter-and intra-individuals and microenvironments between heterotopic-and orthotopic-tumors,limiting the therapeutic efficiency of such nanoplatforms.Herein,various biomimetic nanoplatforms(CCM-modified gold@Carbon,i.e.,Au@C-CCM)were fabricated by coating CCMs of head and neck squamous cell carcinoma(HNSCC)cell lines and patient-derived cells on the surface of Au@C NP.The generated Au@C-CCMs were evaluated on corresponding CDX,tongue orthotopic xenograft(TOX),immunecompetent primary and distant tumor models,and patient-derived xenograft(PDX)models.The Au@C-CCM generates a photothermal conversion efficiency up to 44.2% for primary HNSCC therapy and induced immunotherapy to inhibit metastasis via photothermal therapy-induced immunogenic cell death.The homologous CCM endowed the nanoplatforms with optimal targeting properties for the highest therapeutic efficiency,far above those with mismatched CCMs,resulting in distinct tumor ablation and tumor growth inhibition in all four models.This work reinforces the feasibility of biomimetic NPs combining modular designed CMs and functional cores for customized treatment of HNSCC,can be further extended to other malignant tumors therapy.

A nanocomposite competent to overcome cascade drug resistance in ovarian cancer via mitochondria dysfunction and NO gas synergistic therapy

Ovarian cancer(OC)is one of the most common and recurring malignancies in gynecology.Patients with relapsed OC always develop"cascade drug resistance"(CDR)under repeated chemotherapy,leading to subsequent failure of chemotherapy.To overcome this challenge,amphiphiles(P1)carrying a nitric oxide(NO)donor(Isosorbide 5-mononitrate,ISMN)and high-density disulfide are synthesized for encapsulatingmitochondria-targeted tetravalent platinum prodrug(TPt)to construct a nanocomposite(INP@TPt).Mechanism studies indicated that INP@TPt significantly inhibited drug-resistant cells by increasing cellular uptake and mitochondrial accumulation of platinum,depleting glutathione,and preventing apoptosis escape through generating highly toxic peroxynitrite anion(ONOO−).To better replicate the microenvironmental and histological characteristics of the drug resistant primary tumor,an OC patient-derived tumor xenograft(PDXOC)model in BALB/c nude mice was established.INP@TPt showed the best therapeutic effects in the PDXOC model.The corresponding tumor tissues contained high ONOO−levels,which were attributed to the simultaneous release of O_(2)^(·−)and NO in tumor tissues.Taken together,INP@TPtbased systematic strategy showed considerable potential and satisfactory biocompatibility in overcoming platinum CDR,providing practical applications for ovarian therapy.

Establishment and characterization of a new human ampullary carcinoma cell line,DPC-X1

BACKGROUND An in-depth study of the pathogenesis and biological characteristics of ampullary carcinoma is necessary to identify appropriate treatment strategies. To date, only eight ampullary cancer cell lines have been reported, and a mixed-type ampullary carcinoma cell line has not yet been reported.AIM To establish a stable mixed-type ampullary carcinoma cell line originating from Chinese.METHODS Fresh ampullary cancer tissue samples were used for primary culture and subculture. The cell line was evaluated by cell proliferation assays, clonal formation assays, karyotype analysis, short tandem repeat(STR) analysis and transmission electron microscopy. Drug resistances against oxaliplatin, paclitaxel, gemcitabine and 5-FU were evaluated by cell counting kit-8 assay. Subcutaneous injection 1 × 106 cells to three BALB/c nude mice for xenograft studies. The hematoxylin-eosin staining was used to detect the pathological status of the cell line. The expression of biomarkers cytokeratin 7(CK7), cytokeratin 20(CK20), cytokeratin low molecular weight(CKL), Ki67 and carcinoembryonic antigen(CEA) were determined by immunocytochemistry assay.RESULTS DPC-X1 was continuously cultivated for over a year and stably passaged for more than 80 generations;its population doubling time was 48 h. STR analysis demonstrated that the characteristics of DPC-X1 were highly consistent with those of the patient’s primary tumor. Furthermore, karyotype analysis revealed its abnormal sub-tetraploid karyotype. DPC-X1 could efficiently form organoids in suspension culture. Under the transmission electron microscope, microvilli and pseudopods were observed on the cell surface, and desmosomes were visible between the cells. DPC-X1 cells inoculated into BALB/C nude mice quickly formed transplanted tumors, with a tumor formation rate of 100%. Their pathological characteristics were similar to those of the primary tumor. Moreover, DPC-X1 was sensitive to oxaliplatin and paclitaxel and resistant to gemcitabine and 5-FU. Immunohistochemistry showed that the DPC-X1 cells were strongly positive for CK7, CK20, and CKL;the Ki67 was 50%, and CEA was focally expressed.CONCLUSION Here, we have constructed a mixed-type ampullary carcinoma cell line that can be used as an effective model for studying the pathogenesis of ampullary carcinoma and drug development.

Patient-derived xenograft model in colorectal cancer basic and translational research

Colorectal cancer(CRC)is one of the most popular malignancies globally,with 930000 deaths in 2020.The evaluation of CRC-related pathogenesis and the discovery of po-tential therapeutic targets will be meaningful and helpful for improving CRC treat-ment.With huge efforts made in past decades,the systematic treatment regimens have been applied to improve the prognosis of CRC patients.However,the sensitivity of CRC to chemotherapy and targeted therapy is different from person to person,which is an important cause of treatment failure.The emergence of patient-derived xenograft(PDX)models shows great potential to alleviate the straits.PDX models possess similar genetic and pathological characteristics as the features of primary tu-mors.Moreover,PDX has the ability to mimic the tumor microenvironment of the original tumor.Thus,the PDX model is an important tool to screen precise drugs for individualized treatment,seek predictive biomarkers for prognosis supervision,and evaluate the unknown mechanism in basic research.This paper reviews the recent advances in constructed methods and applications of the CRC PDX model,aiming to provide new knowledge for CRC basic research and therapeutics.

Transitioning of renal transplant pathology from allograft to xenograft and tissue engineering pathology:Are we prepared?

Currently,the most feasible and widely practiced option for patients with endstage organ failure is the transplantation of part of or whole organs,either from deceased or living donors.However,organ shortage has posed and is still posing a big challenge in this field.Newer options being explored are xenografts and engineered/bioengineered tissues/organs.Already small steps have been taken in this direction and sooner or later,these will become a norm in this field.However,these developments will pose different challenges for the diagnosis and management of problems as compared with traditional allografts.The approach to pathologic diagnosis of dysfunction in these settings will likely be significantly different.Thus,there is a need to increase awareness and prepare transplant diagnosticians to meet this future challenge in the field of xenotransplantation/regenerative medicine.This review will focus on the current status of transplant pathology and how it will be changed in the future with the emerging scenario of routine xenotransplantation.

The Inhibitory Effects of Rh-endostatin(YH-16) in Combination with Radiotherapy on Lung Adenocarcinoma A549 in Mice and the Underlying Mechanisms

In order to investigate the inhibitory effects of Endostar(rh-endostatin,YH-16)in combination with radiotherapy on lung adenocarcinoma A549 in mice and the interaction mechanisms of combined therapy,the transplantation tumor models of A549 lung adenocarcinoma were established.When the largest diameter of tumor reached 1.0cm,all nude mice were randomly divided into 4 groups:Endostar group,radiotherapy group,radiotherapy plus Endostar(combined treatment)group,and control group(n=6 in each group).The largest d...

Effect of Bcl-2 Antisense Oligodeoxynucleotides on Human Lung Carcinoma Transplanted Subcutaneously in Nude Mice

Objective： To investigate the inhibitory effects of the Bcl-2 antisense oligodeoxynucleotides （ASODN） on tumor formation and growth of human lung carcinoma transplanted subcutaneously in nude mice. Methods： Human NCI-H460 cells treated with Bcl-2 ASODN or nonesense oligodeoxynucleotide （NSODN） and untreated NCI-H460 cells were respectively implanted subcutaneously into nude mice. When the diameters of tumor were above 0.5 cm after untreated NCI-H460 cells injection, the mice bearing tumor were randomly divided into three groups： saline control group, Bcl-2 ASODN group, NSODN group. ODN was directly injected into the tumor body for 3 weeks. The weight and volume of subcutaneous tumors were measured, and the morphology of tumor cells was observed. Results： The tumorigenic ability of the treated NCI-H460 cells by Bcl-2 ASODN was reduced. The mean time at which tumor can be detected was prolonged up to 12.6 days （P〈0.01）. The maximum tumor growth inhibitory rate was 87.5%. In therapeutic efficacy, growth of tumor was significantly inhibited in Bcl-2 ASODN group as compared with that in NSODN group, saline-treated group （P〈0.01）. The NSODN control was ineffective. In comparison with NSODN-treated, saline-treated mice, those treated with Bcl-2 ASODN showed a significant decrease in median weight of subcutaneous tumors （P〈0.01）. The growth inhibitory rate was 71.0% in ASODN group. Conclusion： Bcl-2 ASODN could inhibit tumor formation and tumor growth in nude mice.

Total Saponins of Aralia elata （Miq.） Seem Leaves （TSAESL） Inhibits Tumor Cell Proliferation and Induces Apoptosis via activating MAPK signaling pathways in MCF-7 human breast cancer cells

Aim Aralia elata （Miq.） Seem is a medicinal plant with a variety of biological activities. Several trier- pene saponins extracted from the leaves of Aralia elata （Miq.） Seem possess potent cytotoxic activity, but the mechanisms remain unclear. Methods In the present study, we examined the anti-tumor activity of total saponins of Aralia elata （Miq.） Seem leaves （TSAESL） using both in vitro and in vivo experiments, and investigated the underlying molecular mechanisms. Results Briefly, TSAESL significantly inhibited the proliferation of five human cancer cell lines and induced apoptosis of MCF-7 cells in a concentration-dependent manner. TSAESL also in- creased the expression level of active caspase-3 and cleaved PARP. In addition, TSAESL dramatically activated the phosphorylation of ERK1/2, p38 and JNK in a concentration-dependent manner. Treatment with the ERK1/2 in- hibitor U0126, p38 inhibitor SB203580, or JNK inhibitor SP600125 prior to TSAESL exposure markedly attenuated TSAESL-induced phosphorylation of ERK1/2 and p38. In mice bearing MCF-7 xenografl, TSAESL markedly inhib- ited tumor growth without significantly affecting spleen coefficient and hematological parameters. Conclusion These results strongly suggest that TSAESL has anti-tumor effect via activating the MAPK-mediated signaling path- ways.

Inhibition of self-renewal and differentiation of HT-29 cells-derived cancer stem-like cells by scutellarin via Hedgehog signaling pathway

OBJECTIVE To investigate the inhibitory effect of scutellarin on the self-renewal and differentiation of HT-29 cells-derived cancer stem-like cells(HT-29CSC)in vitro and in vivo,and to explore its mechanism.METHODS The effect of scutellarin on the growth of HT-29CSC was determined by 3D Culture assay.The effect of scutellarin on growth and transformation of HT-29CSC was probed by soft agar colony formation assay.The effect of scutellarin on the differentiation of HT-29CSC was determined by serum induction differentiation assay in vitro.The effects of scutellarin on the expressions of marker gene Lgr5,target gene c-Myc,proliferation gene CK20 and Nanog gene were measured by quantitative real-time RT-PCR.Investigate the effect of scutellarin on the expression of c-Myc,Gli1,and Lgr5 protein by Western blotting.A subcutaneous xenograft model of colon cancer in nude mice was established and administered by intraperitoneal injection.The change of body weight and tumor size of nude mice were observed every two days.Investi⁃gate the effects of scutellarin on the growth of xenograft tumors in nude mice.The expression of CD133,Lgr5,Gli1,Ptch1,c-Myc,Ki67,CK20,Nanog gene in tumors were measured by quantitative real-time RT-PCR.The expression of c-Myc,Gli1,Lgr5,CD133,Ki67 protein were measured by Western blotting.RESULTS Scutellarin can inhibit the growth of HT-29CSC in 3D culture.Compared with the solvent control group,scutellarin can significantly inhibit the growth and transformation and differentiation of HT-29CSC in vitro(P<0.01).The expression levels of marker genes Lgr5,target gene c-Myc,proliferation gene CK20 and Nanog in HT-29CSC were down-regulated by scutellarin.Scutellarin can reduce the expression of c-Myc,Gli1,and Lgr5 protein in HT-29CSC.Scutellarin can inhibit the growth of colon cancer xenografts,lower CD133,Lgr5,Gli1,Ptch1,c-Myc,Ki67,CK20,and Nanog mRNA level of xenograft tumors,reduce the expression of c-Myc,Gli1,Lgr5,CD133,and Ki67 protein of xenograft tumors in nude mice.CONCLUSION Scutellarin,which is the main component of scutellaria barbata,can inhibit the differentiation of HT-29CSC and the mechanism is to inhibit the activity of Hedgehog signaling pathway.

The effect of rh-endostatin on micrangium and angiogenic factors in tumor and myocardium tissue

Objective： The aim of this study was to compare effect of rh-endostatin on microvasculature in tumor and myocardium tissue. Methods： Nude mice were randomized into 4 groups, blank control group [did not burden tumor, normalsaline （NS） 100 μL/d], drug control group （did not burden tumor, rh-endostatin 400 μg/d）, model group （mice burdened tumor, NS 100 μL/d） and treatment group （mice burdened tumor, rh-endostatin 400 μg/d）, administration was given during d1-d28. The volume of tumor and the weight of mouse were measured before and after administration. The expression of CD34, MMP-2, MMP-9, HIF-la and VEGF in myocardium and tumor were detected by immunohistochemistry. The structure of vasculature was observed by immunoenzymatic double staining with CD34 and Masson. Results： The tumor volume increase of treatment group （48.18 mm3） was less than the model group （113.80 mm3）, the change of weight was not significant among the four groups. After treated with endotar, the expression of MMP-9 and VEGF in tumor were obviously down-regulated, but the same results was not found in MMP-2, HIF-la of tumor. MVD in tumor of treatment group decreased significantly compared with model group. Proportion of tumor vessels covered by collagen in treatment group increased compared with model group. However, MVD and microvasculature in myocardium did not change significantly. Conclusion： Rh-endostatin can decrease the expression of MMP-9, VEGF and MVD to inhibit growth of tumor and normalize micrangium in tumor but cannot weaken MMPs and MVD of mature micrangium in myocardium.

Antiangiogenic therapy for human pancreatic carcinoma xenografts in nude mice

AIM: To investigate the anti-tumor effects of antiangiogenic therapy (a combination of TNP-470, an antiangiogenic compound, with gemcitabine, an antimetabolite) on human pancreatic carcinoma xenografts and its mechanism. METHODS: A surgical orthotopic implantation (SOI) model was established by suturing small pieces of SW1990 pancreatic carcinoma into the tail of pancreas in nude male mice. Mice then received either single therapy (n = 24) or combined therapy (n = 32). Mice receiving single therapy were randomly divided into control group, G100 group receiving 100 mg/kg gemcitabine IP on d O, 3, 6 and 9 after transplantation, and T30 group receiving 30 mg/kg TNP-470 s.c on alternate days for 8 wk. Mice receiving combined therapy were randomly divided into control group, T15 group, G50 group and combination group (TNP-470 30 mg/kg and gemcitabine 50 mg/kg). Animals were killed 8 wk after transplantation. Transplanted tumors, liver, lymph node and peritoneum were removed. Weight of transplanted tumors, the T/C rate (the rate of mean treated tumor weight to mean control tumor weight), change of body weight, metastasis rate, and 9-wk survival rate were investigated. Tumor samples were taken from the control group, T30 group, G100 group and combination group. PCNA index (PI) and microvessel density (MVD) were investigated by immunohistochemical staining for PCNA and factor VIII, respectively. RESULTS: There was a significant inhibitory effect on primary tumor growth of pancreatic carcinoma in G100 group, compared to T30 group, whereas tumor metastasis was significantly inhibited in T30 group compared to G100 group. There was no significant improvement in survival rate in these two groups. No significant inhibitory effect on tumor growth and metastasis in T15 group and G50 group. However, significant anti-tumor and anti-metastatic effects were observed in the combination group with a significant improvement in survival rate. The inhibitory effect on tumor growth in combination group enhanced 2 times in comparison with G50 group and 5 times in comparison with T15 group. Moreover, 25% of the animals hearing tumors were cured by the combination therapy. The levels of MVD and PI were 14.50±5.93 and 0.41±0.02,12.38±1.60 and 0.30±0.07, 7.13±2.99 and 0.37±0.03, and 5.21±1.23 and 0.23±0.02 respectively in the control group, G100 group, T30 group and combination group. A significant inhibitory effect on PI level and MVD level was observed in G100 group and T30 group respectively whereas both MVD and PI levels were significantly inhibited in the combination group (P<0.05). CONCLUSION: Antiangiogenic therapy shows significant anti-tumor and anti-metastatic effects, and is helpful to reduce the dosage of cytotoxic drugs and the side effects. These effects are related to the antiangiogenic effect of TNP-470 and cytotoxic effect of gemcitabine.

Osteopontin increases hepatocellular carcinoma cell growth in a CD44 dependant manner

AIM:To investigate the role of osteopontin(OPN) and its splice variants in the proliferation of hepatocellular carcinoma(HCC).METHODS:The expression of OPN variants in HCC cell lines as well as HCC tissue samples and nontumour tissue was studied using polymerase chain reaction.OPN variant cDNAs were cloned into a mammalian expression vector allowing both transient expression and the production of stable OPN expressing cell lines.OPN expression was studied in these cells using Western blotting,immunofluoresnce and enzyme linked immunosorbent assay.A CD44 blocking antibody and siRNA targeting of CD44 were used to examine the role of this receptor in the OPN stimulated cell growth observed in culture.Huh-7 cells stably expressing either OPN-A,-B or-C were injected subcutaneously into the flanks of nude mice to observe in vivo tumour growth.Expression of OPN mRNA and protein in these tumours was examined using reverse transcriptionpolymerase chain reaction and immunohistochemistry.RESULTS:OPN is expressed in HCC in 3 forms,the full length OPN-A and 2 splice variants OPN-B and-C.OPN variant expression was noted in HCC tissue as well as cognate surrounding cirrhotic liver tissue.Expression of these OPN variants in the HCC derived cell line Huh-7 resulted in secretion of OPN into the culture medium.Transfer of OPN conditioned media to na ve Huh-7 and HepG2 cells resulted in significant cell growth suggesting that all OPN variants can modulate cell proliferation in a paracrine manner.Furthermore the OPN mediated increase in cellular proliferation was dependent on CD44 as only CD44 positive cell lines responded to OPN conditioned media while siRNA knockdown of CD44 blocked the proliferative effect.OPN expression also increased the proliferation of Huh-7 cells in a subcutaneous nude mouse tumour model,with Huh-7 cells expressing OPN-A showing the greatest proliferative effect.CONCLUSION:This study demonstrates that OPN plays a significant role in the proliferation of HCC through interaction with the cell surface receptor CD44.Modulation of this interaction could represent a novel strategy for the control of HCC.

Personalized targeted therapy for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma continues to heavily burden clinicians worldwide. Researchers have discovered the genomic landscape of esophageal squamous cell carcinoma, which holds promise for an era of personalized oncology care. One of the most pressing problems facing this issue is to improve the understanding of the newly available genomic data, and identify the driver-gene mutations, pathways, and networks. The emergence of a legion of novel targeted agents has generated much hope and hype regarding more potent treatment regimens, but the accuracy of drug selection is still arguable. Other problems, such as cancer heterogeneity, drug resistance, exceptional responders, and side effects, have to be surmounted. Evolving topics in personalized oncology, such as interpretation of genomics data, issues in targeted therapy, research approaches for targeted therapy, and future perspectives, will be discussed in this editorial.

Mouse models of pancreatic cancer

Pancreatic cancer is one of the most lethal of human malignancies ranking 4th among cancer-related death in the western world and in the United States,and potent therapeutic options are lacking.Although during the last few years there have been important advances in the understanding of the molecular events responsible for the development of pancreatic cancer,currently specific mechanisms of treatment resistance remain poorly understood and new effective systemic drugs need to be developed and probed.In vivo models to study pancreatic cancer and approach this issue remain limited and present different molecular features that must be considered in the studies depending on the purpose to fit special research themes.In the last few years,several genetically engineered mouse models of pancreatic exocrine neoplasia have been developed.These models mimic the disease as they reproduce genetic alterations implicated in the progression of pancreatic cancer.Genetic alterations such as activating mutations in KRas,or TGFb and/or inactivation of tumoral suppressors such as p53,INK4A/ARF BRCA2 and Smad4 are the most common drivers to pancreatic carcinogenesis and have been used to create transgenic mice.These mouse models have a spectrum of pathologic changes,from pancreatic intraepithelial neoplasia to lesions that progress histologically culminating in fully invasive and metastatic disease and represent the most useful preclinical model system.These models can characterize the cellular and molecular pathology of pancreatic neoplasia and cancer and constitute the best tool to investigate new therapeutic approaches,chemopreventive and/or anticancer treatments.Here,we review and update the current mouse models that reproduce different stages of human pancreatic ductal adenocarcinoma and will have clinical relevance in future pancreatic cancer developments.

Decellularized peripheral nerve grafts by a modified protocol for repair of rat sciatic nerve injury

Studies have shown that acellular nerve xenografts do not require immunosuppression and use of acellular nerve xenografts for repair of peripheral nerve injury is safe and effective.However,there is currently no widely accepted standard chemical decellularization method.The purpose of this study is to investigate the efficiency of bovine-derived nerves decellularized by the modified Hudson’s protocol in the repair of rat sciatic nerve injury.In the modified Hudson’s protocol,Triton X-200 was replaced by Triton X-100,and DNase and RNase were used to prepare accelular nerve xenografts.The efficiency of bovine-derived nerves decellularized by the modified Hudson’s protocol was tested in vitro by hematoxylin&eosin,Alcian blue,Masson’s trichrome,and Luxol fast blue staining,immunohistochemistry,and biochemical assays.The decellularization approach excluded cells,myelin,and axons of nerve xenografts,without affecting the organization of nerve xenografts.The decellularized nerve xenograft was used to bridge a 7 mm-long sciatic nerve defect to evaluate its efficiency in the repair of peripheral nerve injury.At 8 weeks after transplantation,sciatic function index in rats subjected to transplantation of acellular nerve xenograft was similar to that in rats undergoing transplantation of nerve allograft.Morphological analysis revealed that there were a large amount of regenerated myelinated axons in acellular nerve xenograft;the number of Schwann cells in the acellular nerve xenograft was similar to that in the nerve allograft.These findings suggest that acellular nerve xenografts prepared by the modified Hudson’s protocol can be used for repair of peripheral nerve injury.This study was approved by the Research Ethics Committee,Research and Technology Chancellor of Guilan University of Medical Sciences,Iran(approval No.IR.GUMS.REC.1395.332)on February 11,2017.

Gene transfer of somatostatin receptor type 2 by intratumoral injection inhibits established pancreatic carcinoma xenografts

AIM: To investigate the therapeutic effect of somatostatin receptor type 2 (SSTR2) gene transfection on pancreatic carcinoma xenografts in vivo in experimental cancers. METHODS: Human pancreatic cancer cell line Panc-1 was inoculated subcutaneously into the back of nude mice. When tumor nodules were grown as large as about 5 mmx5 mm days after inoculation, the mice were randomly divided into 3 groups (6 mice in each group). Group Ⅰ served as untreated control group. Group Ⅱ received an intratumoral injection of a combination of human cytomegalovirus promoter-6C (pCMV-6C) and lipofectamine 2000. Group Ⅲ received an intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000. The rate of tumor growth was compared among these three groups. The expression of SSTR2 in these tumors was detected by immunohistochemistry and Western-blot. Apoptosis index (AI) in these tumors was examined by using TUNEL in situ. RESULTS: Intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000 resulted in the expression of SSTR2 protein. The tumor size and weight in group Ⅲ (0.318±0.098 cm3, and 0.523±0.090 g, respectively) were significantly lower than those in group I (2.058±0.176 cms, and 1.412±0.146 g, respectively) and group Ⅱ (2.025±0.163 cm3, and 1.365±0.116 g, respectively) (P<0.05) The AI in group Ⅲ (1.47±0.13%) was significantly higher than that in groupⅠ(0.56±0.09%) and group Ⅱ (0.57±0.11%) (P<0.05). But there were no significant differences between groups Ⅰ and Ⅱ. CONCLUSION: Our data demonstrate that re-expression of SSTR2 gene has antitumor effects on experimental pancreatic cancer. Restoration of SSTR2 gene expression through gene transfer in vivo might be a potential gene therapy strategy for human pancreatic cancer.

Mouse models of colorectal cancer: Past, present and future perspectives

Colorectal cancer(CRC)is the third most common diagnosed malignancy among both sexes in the United States as well as in the European Union.While the incidence and mortality rates in western,high developed countries are declining,reflecting the success of screening programs and improved treatment regimen,a rise of the overall global CRC burden can be observed due to lifestyle changes paralleling an increasing human development index.Despite a growing insight into the biology of CRC and many therapeutic improvements in the recent decades,preclinical in vivo models are still indispensable for the development of new treatment approaches.Since the development of carcinogen-induced rodent models for CRC more than 80 years ago,a plethora of animal models has been established to study colon cancer biology.Despite tenuous invasiveness and metastatic behavior,these models are useful for chemoprevention studies and to evaluate colitis-related carcinogenesis.Genetically engineered mouse models(GEMM)mirror the pathogenesis of sporadic as well as inherited CRC depending on the specific molecular pathways activated or inhibited.Although the vast majority of CRC GEMM lack invasiveness,metastasis and tumor heterogeneity,they still have proven useful for examination of the tumor microenvironment as well as systemic immune responses;thus,supporting development of new therapeutic avenues.Induction of metastatic disease by orthotopic injection of CRC cell lines is possible,but the so generated models lack genetic diversity and the number of suited cell lines is very limited.Patient-derived xenografts,in contrast,maintain the pathological and molecular characteristics of the individual patient's CRC after subcutaneous implantation into immunodeficient mice and are therefore most reliable for preclinical drug development–even in comparison to GEMM or cell line-based analyses.However,subcutaneous patient-derived xenograft models are less suitable for studying most aspects of the tumor microenvironment and anti-tumoral immune responses.The authors review the distinct mouse models of CRC with an emphasis on their clinical relevance and shed light on the latest developments in the field of preclinical CRC models.