Synergy of oral recombinant methioninase (rMETase) and 5-fluorouracil on poorly differentiated gastric cancer.

Gastric cancer is highly malignant and recalcitrant to first line chemotherapies that include 5-fluorouracil (5-FU). Cancer cells are addicted to methionine for their proliferation and survival. Methionine addiction of cancer is known as the Hoffman effect. Methionine restriction with recombinant methioninase (rMETase) has been shown to selectively starve cancer cells and has shown synergy with cytotoxic chemotherapy including 5-FU. The present study aimed to investigate the efficacy of rMETase alone and the combination with 5-FU on poorly differentiated human gastric cancer cell lines (MKN45, NUGC3, and NUGC4) in vitro and vivo. rMETase suppressed the tumor growth of 3 kinds of poorly differentiated gastric cancer cells in vitro. The fluorescence ubiquitination-based cell cycle indicator (FUCCI) demonstrated cancer cells treated with rMETase were selectively trapped in the S/G2 phase of the cell cycle. In the present study, subcutaneous MKN45 gastric cancer models were randomized into four groups when the tumor volume reached 100 mm3: G1: untreated control; G2: 5-FU (i.p., 50 mg/kg, weekly, three weeks); G3: oral-rMETase (o-rMETase) (p.o., 100 units/body, daily, three weeks); G4: 5-FU with o-rMETase (5-FU; i.p., 50 mg/kg, weekly, three weeks o-rMETase; p.o., 100 units/body, daily, three weeks). All mice were sacrificed on day 22. Body weight and estimated tumor volume were measured twice a week. 5-FU and o-rMETase suppressed tumor growth as monotherapies on day 18 (p = 0.044 and p = 0.044). However, 5-FU combined with o-rMETase was significantly superior to each monotherapy (p < 0.001 and p < 0.001, respectively) and induced extensive necrosis compared to other groups. The combination of 5-FU and o-rMETase shows promise for transformative therapy for poorly differentiated gastric cancer in the clinic.

Inhibition of pancreatic cancer-cell growth and metastasis in vivo by a pyrazole compound characterized as a cell-migration inhibitor by an in vitro chemotaxis assay.

Pancreatic cancer is recalcitrant to treatment as it is highly metastatic and rapidly progressive. While observing the behavior of human pancreatic BxPC-3 cells using an optical assay device called TAXIScan, we found that several synthetic pyrazole and pyrimidine derivatives inhibited cell migration. One such compound, 14-100, inhibited metastasis of fluorescence-labeled BxPC-3 cells, which were transplanted into the pancreas of nude mice as a subcutaneously grown cancer fragment. Surprisingly, despite its low cytotoxicity, the compound also showed an inhibitory effect on cancer cell proliferation in vivo, suggesting that the compound alters cancer cell characteristics needed to grow in situ. Single-cell RNA-sequencing revealed changes in gene expression associated with metastasis, angiogenesis, inflammation, and epithelial-mesenchymal transition. These data suggest that the compound 14-100 could be a good drug candidate against pancreatic cancer.

Obesity Strongly Promotes Growth of Mouse MC38 Colon Cancer in an Orthotopic-syngeneic C57BL/6 Mouse Model.

BACKGROUND/AIM: Obesity is a major risk factor for colorectal cancer. The MC38 mouse colon-cancer cell line is a versatile syngeneic model of colon cancer in C57BL/6 mice. In the present study, the influence of a high-fat diet (HFD) on the growth of the MC38 mouse colon-cancer cell line was examined in an orthotopic-transplantation syngeneic model in C57BL/6 mice. MATERIALS AND METHODS: Five 6-week-old C57BL/6 male mice were fed a control diet (CD, 6.5% fat) or HFD (34.3% fat) for eight weeks. Then, a 2 mm3 fragment of a subcutaneous MC38 tumor was attached to the surface of the cecum of C57BL/6 mice with a single stitch using a 7-0 suture to establish an orthotopic-transplantation model. Each group continued their initial diet for 17 days. RESULTS: The HFD group had more than twice the tumor volume and tumor weight than the CD group (p=0.021 and p=0.014, respectively). CONCLUSION: HFD-induced obesity strongly increased MC38 colon-cancer progression in a C57BL/6 orthotopic-transplantation mouse model. The present study emphasizes the detrimental effect of obesity on coloncancer progression.

Linkage of methionine addiction, histone lysine hypermethylation, and malignancy.

Methionine addiction, found in all types of cancer investigated, is because of the overuse of methionine by cancer cells for excess transmethylation reactions. In the present study, we compared the histone H3 lysine-methylation status and degree of malignancy between methionine-addicted cancer cells and their isogenic methionine-independent revertants, selected by their growth in low concentration of methionine. The methionine-independent revertans can grow on low levels of methionine or independently of exogenous methionine using methionine precursors, as do normal cells. In the methionine-independent revertants, the excess levels of trimethylated histone H3 lysine marks found in the methionine-addicted parental cancer cells were reduced or lost, and their tumorigenicity and experimental metastatic potential in nude mice were also highly reduced. Methionine addiction of cancer is linked with malignancy and hypermethylation of histone H3 lysines. The results of the present study thus provide a unique framework to further understand a fundamental basis of malignancy.

High Incidence of Lymph-node Metastasis in a Pancreatic-cancer Patient-derived Orthotopic Xenograft (PDOX) NOG-Mouse Model.

BACKGROUND/AIM: Our laboratory pioneered the patient-derived orthotopic xenograft (PDOX) model. An important goal of PDOX-model development is facile visualization of metastasis in live mice. In the present report we evaluated tumor growth and metastasis in pancreatic cancer PDOX NOG [Non-obese diabetes (NOD)/Scid/IL2Rγnull]-and nude-mouse models using red fluorescent protein (RFP)-expressing tumor stroma to visualize the primary tumor and metastasis. MATERIALS AND METHODS: A patient-derived pancreatic cancer was initially implanted in transgenic RFP-expressing nude mice. Then, tumor fragments, which acquired RFP expressing stroma while growing in RFP-expressing nude mice were orthotopically implanted in nude and NOG mice. The primary pancreatic tumor and metastasis were observed 8 weeks after implantation. RESULTS: Lymph-node metastases expressing red fluorescence were detected only in NOG mice. Significantly faster growth of primary pancreatic tumors and a higher incidence of lymph-node metastasis occurred in NOG mice compared to nude mice. CONCLUSION: RFP-expressing tumor stroma, which traffics together with cancer cells to lymph nodes, is useful to observe tumor behavior, such as lymph-node metastasis in a PDOX NOG-mouse model which can be used for evaluation of novel anti-metastatic agents, as well as personalized therapy to identify effective drugs.

A Phenylfurocoumarin Derivative Reverses ABCG2-Mediated Multidrug Resistance In Vitro and In Vivo.

The ATP-binding cassette subfamily G member 2 (ABCG2) transporter is involved in the development of multidrug resistance in cancer patients. Many inhibitors of ABCG2 have been reported to enhance the chemosensitivity of cancer cells. However, none of these inhibitors are being used clinically. The aim of this study was to identify novel ABCG2 inhibitors by high-throughput screening of a chemical library. Among the 5812 compounds in the library, 23 compounds were selected in the first screening, using a fluorescent plate reader-based pheophorbide a (PhA) efflux assay. Thereafter, to validate these compounds, a flow cytometry-based PhA efflux assay was performed and 16 compounds were identified as potential inhibitors. A cytotoxic assay was then performed to assess the effect these 16 compounds had on ABCG2-mediated chemosensitivity. We found that the phenylfurocoumarin derivative (R)-9-(3,4-dimethoxyphenyl)-4-((3,3-dimethyloxiran-2-yl)methoxy)-7H-furo [3,2-g]chromen-7-one (PFC) significantly decreased the IC50 of SN-38 in HCT-116/BCRP colon cancer cells. In addition, PFC stimulated ABCG2-mediated ATP hydrolysis, suggesting that this compound interacts with the substrate-binding site of ABCG2. Furthermore, PFC reversed the resistance to irinotecan without causing toxicity in the ABCG2-overexpressing HCT-116/BCRP cell xenograft mouse model. In conclusion, PFC is a novel inhibitor of ABCG2 and has promise as a therapeutic to overcome ABCG2-mediated MDR, to improve the efficiency of cancer chemotherapy.

Salmonella typhimurium A1-R Exquisitely Targets and Arrests a Matrix-producing Triple-negative Breast Carcinoma in a PDOX Model.

BACKGROUND/AIM: Triple-negative matrix-producing breast carcinoma (MPBC) is rare, recalcitrant, and highly aggressive. The present study aimed to determine the efficacy of tumor-targeting leucine-arginine auxotroph Salmonella typhimurium (S. typhimurium) A1-R on a triple-negative MPBC in a patient-derived orthotopic xenograft (PDOX) model. MATERIALS AND METHODS: The PDOX MPBC model was established in the left second mammary gland of nude mice by surgical orthotopic implantation (SOI). PDOX models were randomized into two groups when the tumor volume reached over 70 mm3: a control group (n=6); and a tumor-targeting S. typhimurium A1-R group (n=7), [intravenous (i.v.) injection of S. typhimurium A1-R via the tail vein, weekly, for two weeks]. All mice were sacrificed on day 14. Tumor volume and body weight were measured once per week. RESULTS: S. typhimurium A1-R exquisitely targeted and arrested the growth of the MPBC PDOX compared to the control group (p=0.017). CONCLUSION: S. typhimurium A1-R has future clinical potential for triple-negative MPBC patients.

Combination of CDK4/6 and mTOR Inhibitors Suppressed Doxorubicin-resistant Osteosarcoma in a Patient-derived Orthotopic Xenograft Mouse Model: A Translatable Strategy for Recalcitrant Disease.

BACKGROUND: Osteosarcoma is the most frequent malignant bone neoplasm. The efficacy of combination therapy of a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor and a mammalian-target-of-rapamycin (mTOR) inhibitor was previously reported in several cancer types. In the present study, we evaluated the efficacy of a combination of palbociclib (CDK 4/6 inhibitor) and everolimus (mTOR inhibitor) on an osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model. MATERIALS AND METHODS: osteosarcoma PDOX mouse models were randomized into five treatment groups of seven mice each: Group 1, untreated control; group 2, doxorubicin treatment; group 3, palbociclib treatment; group 4, everolimus treatment; group 5, palbociclib-everolimus combination treatment. Treatment duration was 2 weeks. RESULTS: The palbociclib-everolimus combination reduced the tumor-volume ratio in the osteosarcoma PDOX mouse model compared with the control and doxorubicin (p=0.018). Everolimus alone also inhibited osteosarcoma PDOX growth compared to the control (p=0.04), but less than the combination. Palbociclib alone and doxorubicin were ineffective. There were no significant body-weight losses in any group. Only the palbociclib-everolimus combination induced extensive tumor necrosis observed histopathologically. CONCLUSION: The present study demonstrated that the combination of CDK4/6 and mTOR inhibitors can be a translatable approach for doxorubicin-resistant osteosarcoma in the clinic.

An mTOR and VEGFR inhibitor combination arrests a doxorubicin resistant lung metastatic osteosarcoma in a PDOX mouse model.

In order to identify more effective therapy for recalcitrant osteosarcoma, we evaluated the efficacy of an mTOR-VEGFR inhibitor combination on tumor growth in a unique osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model derived from the lung metastasis of an osteosarcoma patient who failed doxorubicin therapy. We also determined the efficacy of this inhibitor combination on angiogenesis using an in vivo Gelfoam fluorescence angiogenesis mouse model implanted with osteosarcoma patient-derived cells (OS-PDCs). PDOX models were randomly divided into five groups of seven nude mice. Group 1, control; Group 2, doxorubicin (DOX); Group 3, everolimus (EVE, an mTOR and VEGF inhibitor); Group 4, pazopanib (PAZ, a VEGFR inhibitor); Group 5, EVE-PAZ combination. Tumor volume and body weight were monitored 2 times a week. The in vivo Gelfoam fluorescence angiogenesis assay was performed with implanted OS-PDCs. The nude mice with implanted Gelfoam and OSPDCs also were divided into the four therapeutic groups and vessel length was monitored once a week. The EVE-PAZ combination suppressed tumor growth in the osteosarcoma PDOX model and decreased the vessel length ratio in the in vivo Gelfoam fluorescent angiogenesis model, compared with all other groups (p < 0.05). There was no significant body-weight loss in any group. Only the EVE-PAZ combination caused tumor necrosis. The present study demonstrates that a combination of an mTOR-VEGF inhibitor and a VEGFR inhibitor was effective for a DOX-resistant lung-metastatic osteosarcoma PDOX mouse model, at least in part due to strong anti-angiogenesis efficacy of the combination.

Oral recombinant methioninase combined with paclitaxel arrests recalcitrant ovarian clear cell carcinoma growth in a patient-derived orthotopic xenograft (PDOX) nude-mouse model.

PURPOSE: Advanced ovarian clear cell carcinoma (OCCC) is a recalcitrant disease, often resistant to the first-line platinum-based therapy. Using a novel patient-derived orthotopic xenograft (PDOX) nude-mouse model of OCCC, we tested whether oral-recombinant methioninase (o-rMETase) could enhance the efficacy of paclitaxel (PTX). METHODS: The OCCC PDOX model was established and passaged in nude mice. The OCCC PDOX models were randomized into 5 groups. G1: untreated control; G2: paclitaxel (PTX) (20 mg/kg, intraperitoneal (i.p.) injection, weekly); G3: o-rMETase (100 units, oral, daily); G4: PTX (20 mg/kg, i.p. injection, weekly) + carboplatinum (CBDCA) (40 mg/kg, i.p. injection weekly); G5: PTX (20 mg/kg, i.p. injection, weekly) + o-rMETase (100 units, oral, daily). The treatment period was 2 weeks. RESULTS: The combination of PTX and o-rMETase arrested OCCC tumor growth (relative tumor volume: 1.09 ± 0.63 (mean ± SD)) compared with the untreated control (relative tumor volume: 3.92 ± 1.04 (mean ± SD)) (p < 0.0001). There was no significant difference in relative tumor volume between PTX plus o-rMETase and PTX plus CBDCA (relative tumor volume: 1.39 ± 0.37 (mean ± SD)) (p = 0.93). CONCLUSION: PTX plus o-rMETase arrested the OCCC tumor growth. o-rMETase is readily administered and can greatly enhance first-line therapy of a recalcitrant cancer. The novel and effective treatment strategy in the present report has future clinical potential for patients with OCCC, especially for patients who cannot well tolerate platinum-based therapy.

Combination Methionine-methylation-axis Blockade: A Novel Approach to Target the Methionine Addiction of Cancer.

BACKGROUND/AIM: Cancers are selectively sensitive to methionine (MET) restriction (MR) due to their addiction to MET which is overused for elevated methylation reactions. MET addiction of cancer was discovered by us 45 years ago. MR of cancer results in depletion of S-adenosylmethionine (SAM) for transmethylation reactions, resulting in selective cancer-growth arrest in the late S/G2-phase of the cell cycle. The aim of the present study was to determine if blockade of the MET-methylation axis is a highly-effective strategy for cancer chemotherapy. MATERIALS AND METHODS: In the present study, we demonstrated the efficacy of MET-methylation-axis blockade using MR by oral-recombinant methioninase (o-rMETase) combined with decitabine (DAC), an inhibitor of DNA methylation, and an inhibitor of SAM synthesis, cycloleucine (CL). We determined a proof-of-concept of the efficacy of the MET-methylation-axis blockade on a recalcitrant undifferentiated/unclassified soft-tissue sarcoma (USTS) patient-derived orthotopic xenograft (PDOX) mouse model. RESULTS: The o-rMETase-CL-DAC combination regressed the USTS PDOX with extensive cancer necrosis. CONCLUSION: The new concept of combination MET-methylation-axis blockade is effective and can now be tested on many types of recalcitrant cancer.

A Novel Orthotopic Mouse Model of Lung Metastasis Using Fluorescent Patient-derived Osteosarcoma Cells.

BACKGROUND: A mouse model of metastatic osteosarcoma is imperative to identify effective agents for metastatic osteosarcoma, which is a recalcitrant disease. In the present study, we established osteosarcoma patient-derived cells (OS-PDCs) and transfected them with green fluorescent protein (GFP). MATERIALS AND METHODS: The OS-PDCs were transfected with GFP-lentivirus. GFP-expressing OS-PDCs (2.0×105) were then injected into the tibia of nude mice to establish the patient-derived orthotopic cell (PDOC) model (n=3). Six weeks after injection, the primary tumor and each organ were resected and imaged. RESULTS: Primary orthotopic tumors were established in two out of three mice. The GFP-expressing OS-PDCs in the PDOC model were visualized. Multiple GFP-expressing lung metastases were detected in one of the two mice with primary tumor. CONCLUSION: The present study proves the concept that a GFP-expressing PDOC model can mimic clinical lung-metastatic osteosarcoma. This model can serve as a paradigm to screen for effective drugs for osteosarcoma lung metastasis.

Reversion from Methionine Addiction to Methionine Independence Results in Loss of Tumorigenic Potential of Highly-malignant Lung-cancer Cells.

BACKGROUND/AIM: Methionine addiction, a fundamental and general hallmark of cancer, is due to the excess use of methionine for transmethylation, and is described as the Hoffman-effect. Methionine-addicted cancer cells can revert at low frequency to methionine independence when selected under methionine-restriction. We report here that highly-malignant methionine-addicted H460 human lung-cancer cells, when selected for methionine independence, have greatly-reduced tumorigenic potential. MATERIALS AND METHODS: Methionine-addicted H460 parental cancer cells and methionine-independent revertant H460-R1 cells were injected in nude mice subcutaneously. RESULTS: When the parental H460 methionine-addicted cells were injected in nude mice at 2.5×105, 1×105 and 5×104, the cells could form tumors. In contrast, the H460-R1 methionine-independent revertant cells could not form tumors when the above-listed cell numbers were injected in nude mice. CONCLUSION: There is a tight linkage between methionine addiction and malignancy.

Triple-Methyl Blockade With Recombinant Methioninase, Cycloleucine, and Azacitidine Arrests a Pancreatic Cancer Patient-Derived Orthotopic Xenograft Model.

OBJECTIVES: Methionine addiction is a fundamental and general hallmark of cancer caused by enhanced methyl flux. In the present study, we effected a novel methionine-methylation blockade to target a patient-derived orthotopic xenograft model of pancreatic cancer. METHODS: The pancreatic cancer patient-derived orthotopic xenograft mouse models were randomized into 6 groups of 8 mice each and treated for 2 weeks: untreated control; azacitidine; oral recombinant methioninase (o-rMETase); o-rMETase plus cycloleucine; o-rMETase plus cycloleucine plus azacitidine (triple-methyl blockade therapy); and gemcitabine (positive control). RESULTS: Triple-methyl blockade therapy arrested tumor growth (mean relative tumor volume, 1.03 [standard deviation, 0.36]) and was significantly more effective compared with azacitidine (P = 0.0001); o-rMETase (P = 0.007); or o-rMETase plus cycloleucine (P = 0.04). Gemcitabine alone also inhibited but did not arrest tumor growth (mean relative tumor volume, 1.50 [standard deviation, 0.30]). The percentage of cancer cells that were negative for 5-methylcytosine staining in immunohistochemistry, indicating reduction of DNA methylation, increased with triple-methyl blockade therapy (37.5%), compared with gemcitabine (1.8%); o-rMETase (2.8%); azacitidine (9.0%); or o-rMETase plus cycloleucine (10.6%). CONCLUSIONS: This new concept of triple-methyl blockade therapy has clinical potential for pancreatic cancer, which is currently a recalcitrant disease.

[Complete Response to Neoadjuvant Chemotherapy with Imatinib of a Large Gastric GIST-A Case Report].

A 54-year-old woman was presented with the intraabdominal mass to our hospital. Abdominal CT showed 22 cm tumor of the stomach with invasion to the pancreas and the spleen. Upper GI endoscopy showed submucosal tumor at the stomach body, and endoscopic US showed low echoic tumor. The tumor was diagnosed as gastric GIST by biopsy with c-kit positive cells. After 4 months of neoadjuvant therapy with imatinib, she underwent total gastrectomy, distal pancreatectomy and splenectomy. Histopathologically, there were no viable tumor cells in the resected specimen. The patient has no evidence of recurrence at 8 months post operation.

A Universal Gelfoam 3-D Histoculture Method to Establish Patient-derived Cancer Cells (3D-PDCC) Without Fibroblasts from Patient-derived Xenografts.

BACKGROUND/AIM: The direct placement of patient tumors in 2-D culture on plastic or glass surfaces has inhibited the establishment of patient-derived cancer cells (PDCCs). The aim of the present study was to develop universal and efficient methods to prepare PDCCs. MATERIALS AND METHODS: Fragments of patient-derived xenograft (PDX) tumors established form colon cancer liver metastasis (1 mm3) were placed on Gelfoam and cultured in DMEM. RESULTS: PDX tumor fragments were cultured on Gelfoam. Cancer cells migrated from the explant and formed distinct 3-D structures in the Gelfoam. Each of the three PDCCs showed a distinct morphology. The cultures were essentially all cancer cells without fibroblasts, the opposite of what usually occurs in 2-D culture on plastic or glass. Gelfoam cultures could be readily passaged from one Gelfoam cube to anothers suggesting indefinite culture potential. CONCLUSION: A potentially universal method to establish PDCC using PDX tumors and 3-D Gelfoam histoculture was developed.

Ligation Method to Specifically Label a Liver Segment With Indocyanine Green in an Orthotopic Nude-Mouse Liver-Metastasis Model.

BACKGROUND/AIM: The visualization of hepatic segments with indocyanine green (ICG) fluorescence can aid in anatomic liver resection. The present study aimed to develop a method to specifically label an hepatic segment in a nude mouse model with liver metastasis. MATERIALS AND METHODS: An orthotopic mouse model was established by surgical orthotopic implantation (SOI) of a patient-derived colon-cancer liver metastasis in the left lobe of the liver. Three weeks after SOI, the left Glissonean pedicle was ligated and 10 µg ICG was administrated intravenously. Images were obtained with the Pearl Trilogy Imaging System. RESULTS: All mice expressed an 800 nm signal from ICG on the right lobe of the liver. The left lobe of the liver, in which the tumor was located, showed no fluorescence and had ischemia due to successful ligation of the Glissonean pedicle. CONCLUSION: The ligation of the Glissonean pedicle enables specific liver-segment labeling with ICG, which has potential clinical application for liver metastasectomy.

Sutureless Surgical Orthotopic Implantation Technique of Primary and Metastatic Cancer in the Liver of Mouse Models.

BACKGROUND/AIM: Surgical orthotopic implantation (SOI) is used to establish patient-derived orthotopic xenograft (PDOX) and other orthotopic mouse models. Orthotopic liver models can be challenging, as the liver parenchyma is prone to bleeding. The present report describes a sutureless method to implant tumors in the liver that reduces bleeding and procedural time. MATERIALS AND METHODS: Human HCC cell-line (Huh-7-GFP) and CM2, a patient-derived colon-cancer liver metastasis, were used for sutureless SOI of tumor fragments in the liver of nude mice. A small cavity was formed on the liver surface. A solitary tumor fragment was implanted in the cavity without suturing to create hemostasis. RESULTS: Six weeks after sutureless SOI, the tumor volume of Huh-7-GFP (n=5) was 584.41±147.64 mm3 and the tumor volume of CM2 (n=5) was 1336.54±1038.20 mm3 The engraftment rate was 100%. CONCLUSION: This novel method for establishing orthotopic liver-implantation mouse models is suitable for studies of liver cancer and liver metastases due to its simple procedure and potential high engraftment rate.

Response of Triple-negative Breast Cancer Liver Metastasis to Oral Recombinant Methioninase in a Patient-derived Orthotopic Xenograft (PDOX) Model.

BACKGROUND/AIM: The aim of this study was to establish a patient-derived orthotopic xenograft (PDOX) mouse model of liver metastasis of triple-negative breast cancer (TNBC) and examine the efficacy of oral recombinant methioninase (o-rMETase) on the liver metastasis. MATERIALS AND METHODS: TNBC from a patient was implanted in the left hepatic lobe of nude mice to simulate liver metastasis in a PDOX model. Ten days later, all mice underwent laparotomy to measure tumor size and were randomized to three groups: control; o-rMETase 100 U once daily (qd); and o-rMETase 200 U qd. After 9 days of treatment, all mice were sacrificed. RESULTS: At the end of the treatment period for the liver metastasis, the size of liver metastases was 372.6 mm3 in the control group; 160.0 mm3 in the o-rMETase 100 U group; and 245.3 mm3 in the o-rMETase 200 U group. All mice had ascites and 12 out of 14 mice in all groups had mesenteric lymph-node metastasis, as re-metastasis. The mean body-condition score was 1.5 in the control group; 2.4 in the o-rMETase 100 U group; and 2.6 in the o-rMETase 200 U group (control group vs. o-rMETase 200 U group, p<0.05). CONCLUSION: The TNBC liver metastasis was highly aggressive resulting in re-metastasis and ascites. o-rMETase tended to inhibit the liver metastasis and significantly improved the mouse body-condition score. This new PDOX model of TNBC liver metastasis will be useful for identifying effective agents for this recalcitrant disease.

A Non-invasive Imageable GFP-expressing Mouse Model of Orthotopic Human Bladder Cancer.

BACKGROUND/AIM: A more realistic mouse model of bladder cancer is necessary to develop effective drugs for the disease. Tumor models enhanced by bright fluorescent-reporter genes to follow the disease in real-time would enhance the ability to accurately predict the efficacy of various therapeutics on this particularly-malignant human cancer. MATERIALS AND METHODS: A highly-fluorescent green fluorescent protein (GFP)-expressing bladder cancer model was orthotopically established in nude mice using the UM-UC-3 human bladder-cancer cell line (UM-UC-3-GFP). Fragments from a subcutaneous tumor of UM-UC-3-GFP were surgically implanted into the nude mouse bladder. Non-invasive and intra-vital fluorescence imaging was obtained with a simple imaging box. RESULTS: The GFP-expressing orthotopic bladder tumor was imaged in real-time non-invasively as well as intra-vitally, with the two methods correlating at r=0.99. CONCLUSION: This is the first non-invasive-fluorescence-imaging orthotopic model of bladder cancer and can be used for rapidly screening novel effective agents for this recalcitrant disease.