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Biomedical subjects

A R Moossa

Publications and source records attributed to A R Moossa.

At least 55 records · Page 3Linked to original sources

Survival efficacy of the combination of the methioninase gene and methioninase in a lung cancer orthotopic model.

We have previously demonstrated the antitumor efficacy of recombinant methioninase (rMETase) derived from Pseudomonas putida. To enhance the efficacy of rMETase, we have constructed the pLGFP-METSN retrovirus encoding the P. putida methioninase (MET) gene fused with the green fluorescent protein (GFP) gene. pLGFP-METSN or control vector pLGFPSN was introduced into the human lung cancer cell line H460. The methionine level of H460-GFP-MET cells was reduced to 33% of that of H460-GFP cells. rMETase (0.08 U/mL) in the medium resulted in 10% survival of H460-GFP-MET cells compared with untreated cells in vitro. In contrast, rMETase-treated H460-GFP cells survived at 90% of control. Tissue fragments harvested from subcutaneous tumors of H460-GFP-MET or H460-MET were implanted by surgical orthotopic implantation into the lungs of nude mice. A suboptimal dose of rMETase was administered intraperitoneally daily to mice in each group. Overall survival of rMETase-treated animals with H460-GFP-MET tumors was significantly longer than either rMETase-treated or -untreated animals with H460-GFP tumors (P < .05 in log-rank test). In two repeat experiments, rMETase-treated animals with H460-GFP-MET tumors had a 30-day survival of 80% and 83%, respectively. Untreated animals with H460-GFP-MET tumors had a 30-day survival of 40% and 58%, respectively. rMETase-treated animals with H460-GFP tumors had a 30-day survival of 0% and 33%, respectively. Untreated animals with H460-GFP tumors had a 30-day survival of 0% and 33%, respectively. The retrovirus-mediated gene transfer of METase decreased the intracellular methionine level of tumor cells and consequently enhanced the efficacy of treatment with the rMETase protein. We have thus demonstrated a new strategy of combination tumor therapy with the gene and gene product of MET.

Animals↗

In vivo tumor delivery of the green fluorescent protein gene to report future occurrence of metastasis.

The green fluorescent protein (GFP) gene was administered to intraperitoneally (i.p.) growing human stomach cancer in nude mice to visualize future regional and distant metastases. GFP retroviral supernatants were injected i.p. from day 4 to day 10 after i.p. implantation of the cancer cells. Tumor and metastasis fluorescence was visualized every other week with the use of fluorescence optics via a laparotomy on the tumor-bearing animals. At 2 weeks after retroviral GFP delivery, GFP-expressing tumor cells were observed in gonadal fat, greater omentum, and intestine, indicating that these primary i.p. growing tumors were efficiently transduced by the GFP gene and could be visualized by its expression. At the second and third laparotomies, GFP-expressing tumor cells were observed to have spread to lymph nodes in the mesentery and other regional sites. At the fourth laparotomy, widespread tumor growth was visualized by GFP expression, inducing liver metastasis. No normal tissues were found to be transduced by the GFP retrovirus. Thus, reporter gene transduction of the primary tumor enabled detection of its subsequent metastasis. This gene therapy model could be applied to primary tumors before resection or other treatment to have a fluorescent early detection system for metastasis and recurrence.

3T3 Cells↗

Antimetastatic intraoperative chemotherapy of human colon tumors in the livers of nude mice.

We have developed a new antimetastatic chemotherapeutic strategy for combination with hepatic resection of human colon cancers in a high-metastasis nude mouse model. The new procedure involves i.p. administration of 5-fluorouracil (5-FU) 2 h before hepatic resection of the human colon tumors, with therapy continued postoperatively for 4 consecutive days. We termed this strategy neo-neoadjuvant chemotherapy. The regime significantly prolonged animal survival compared with preoperative 5-FU neoadjuvant therapy, 5-FU postoperative adjuvant therapy, surgery alone, 5-FU without surgery, or the untreated control. The median survival of neo-neoadjuvant i.p. 5-FU-treated group was 81 days, compared with 27 days for the control group (P < 0.009). The median survival of animals in the neoadjuvant group was 37 days (P < 0.021 compared with the control group). There was also a significant difference between the median survival of neo-neoadjuvant, and the neoadjuvant group (P < 0.031). When all animals in the control group had died, 70% of animals with neo-neoadjuvant and 60% of animals with neoadjuvant 5-FU were still alive (P < 0.003 and P < 0.011, respectively). When all animals with neoadjuvant 5-FU treatment had died, 70% of animals with neo-neoadjuvant treatment were still alive (P < 0.003). Survival of all other treatment groups, including 5-FU without surgery, surgery alone, and adjuvant postoperative chemotherapy, was not significantly different from the untreated control group. Two animals in the neo-neoadjuvant group were free of tumors when sacrificed at days 154 and 165 post surgery. Whereas 100% of animals in the control, 90% in the 5-FU alone, 70% in the surgery alone, 60% in the 5-FU adjuvant, and 40% in the neoadjuvant groups had metastases in the lymph nodes draining the liver, only 10% of animals in the neo-neoadjuvant group had metastases. These data suggest that the neo-neoadjuvant therapy increased survival by preventing metastasis of cancer cells not removed in the liver resection procedure. The results of this study indicate that the neo-neoadjuvant treatment strategy for resection of colon cancer liver metastasis should be explored clinically.

Animals↗

An orthotopic mouse model of remetastasis of human colon cancer liver metastasis.

Whether liver metastases from colon cancer are capable of metastasizing to other sites is an important question in surgical oncology. To answer this question, we have developed a highly metastatic orthotopic transplant model of a liver metastasis from a human colon cancer patient in nude mice that targets the liver and lymph nodes. The metastatic human tumor was transplanted in athymic nude mice by surgical orthotopic implantation (SOI) of a liver metastasis from a colon cancer patient. The human colon tumor was then subsequently implanted in the colon by SOI or, in an additional series of nude mice, in the liver by surgical hepatic implantation (SHI). The mice were then explored over time for lymph node involvement beginning 10 days after implantation. After SOI, 100% of the animals had liver metastasis within 10 days, and subsequently, 19 days after SOI, all lymph nodes draining the liver were involved with metastasis without any retroperitoneal or lung tissue involvement. After SHI, all sites of lymphatic drainage of the liver, including portal, celiac, and mediastinal lymph nodes, were massively involved by metastasis in 100% of the animals as early as 10 days after tumor implantation on the liver. The results of this study demonstrate that liver metastases from colon cancer are capable of remetastasizing to other sites. This study thus suggests that in colon cancer patients with liver metastasis, mediastinal, celiac, and portal lymph node metastases originate from the liver metastasis and not, as previously thought, from primary colon cancer.

Adenocarcinoma↗

A fluorescent orthotopic bone metastasis model of human prostate cancer.

Here, we report a fluorescent spontaneous bone metastatic model of human prostate cancer developed by surgical orthotopic implantation of green fluorescent protein (GFP)-expressing prostate cancer tissue. Human prostate cancer PC-3 cells were transduced with the pLEIN expression retroviral vector containing the enhanced GFP and neomycin resistance genes. Stable GFP high-expression PC-3 clones were selected in vitro with G418, which were then combined and injected s.c. in nude mice. For metastasis studies, fragments of a single highly fluorescent s.c. growing tumor were implanted by surgical orthotopic implantation in the prostate of a series of nude mice. Subsequent micrometastases and metastases were visualized by GFP fluorescence throughout the skeleton, including the skull, rib, pelvis, femur, and tibia The central nervous system, including the brain and spinal cord, was also involved with tumor, as visualized by GFP fluorescence. Systemic organs, including the lung, plural membrane, liver, kidney, and adrenal gland, also had fluorescent metastases. The metastasis pattern in this model reflects the bone and other metastatic sites of human prostate cancer. Thus, this model should be very useful for the study and development of treatment for metastatic androgen-independent prostate cancer.

Animals↗

Development of a high metastatic orthotopic model of human renal cell carcinoma in nude mice: benefits of fragment implantation compared to cell-suspension injection.

In this study we compared the metastatic rate of human renal cell carcinoma SN12C in two orthotopic nude mouse models: surgical orthotopic implantation (SOI) of histologically intact tumor tissue and cellular orthotopic injection (COI) of cell suspensions in the kidney. The primary tumors resulting from SOI were larger and much more locally invasive than primary tumors resulting from COI. SOI generated higher metastatic expression than COI. The differences in metastatic rates in the involved organs (lung, liver, and mediastinal lymph nodes) were 2-3 fold higher in SOI compared to COI (P < 0.05). Median survival time in the SOI model was 40 days, which was significantly shorter than that of COI (68 days) (P < 0.001). Histological observation of the primary tumors from the SOI model demonstrated a much richer vascular network than the COI model. Lymph node and lung metastases were larger and more cellular in the SOI model compared to COI. We conclude that the tissue architecture of the implanted tumor tissue in the SOI model plays an important role in the initiation of primary tumor growth, invasion, and distant metastasis. This study directly demonstrates that the implantation of histologically intact tumor tissue orthotopically allows accurate expression of the clinical features of human renal cancer in nude mice. This model should be of value in cancer research and antimetastatic drug discovery for renal cancer, a currently very poorly responding malignancy.

Adult↗

Multi-organ metastatic capability of Chinese hamster ovary cells revealed by green fluorescent protein (GFP) expression.

Stable high-level green fluorescent protein (GFP)-expressing Chinese hamster ovary cells (CHO) were used to visualize the degree of metastatic behavior of this cell line in nude and SCID mice. A stable GFP high-expression CHO clone, selected in 1.5 microM methotrexate, was injected subcutaneously in nude and severe combined immunodeficient (SCID) mice and implanted orthotopically in the ovary of nude mice. CHO proved to be highly metastatic from both the subcutaneous and orthotopic sites as brightly visualized by GFP fluorescence. High-level GFP-expression allowed the visualization of metastatic tumor in fresh live host tissue in great detail. Metastases were visualized by GFP expression in the lung, pleural membrane, spleen, kidney, ovary, adrenal gland, and peritoneum after orthotopic implantation in nude mice. Metastases were visualized by GFP expression mainly in the lung, pleural membrane after subcutaneous implantation in nude mice. Metastases were visualized in the lung and pleural membrane, liver, kidney, and ovary after subcutaneous implantation in SCID mice. The construction of highly fluorescent stable GFP transfectants of CHO has revealed the multi-organ metastatic capability of CHO cells. CHO has such a high degree of malignancy that it is metastatic from both the orthotopic and subcutaneous transplant sites. This highly malignant GFP-expressing cell-line with multi-organ metastatic affinity should serve as a powerful tool to study tumor-host interaction.

Animals↗

Minimal liver resection strongly stimulates the growth of human colon cancer in the liver of nude mice.

Partial hepatectomy has been widely employed in clinical practice as the therapy of choice for primary and metastatic liver tumors. However, the recurrence rate after the treatment remains high, which is most likely due to the growth of residual microscopic lesions. Previous studies in murine models demonstrated that a 70% hepatectomy significantly accelerated the growth of ectopically implanted tumors. In this study, we reported the effect of partial hepatectomy on the growth of two human colon cancers (Co-3 and AC3603) implanted in the liver of nude mice using the technique of surgical implantation of histologically intact tumor tissue. Our results showed a dramatic acceleration of tumor growth following 30% partial hepatectomy, which resembles clinical procedures. Tumor volumes were assessed with calipers on day-15 by abdominal palpation and on day-30 at autopsy by direct measurement. For both Co-3 and AC3603, tumor volumes in the hepatectomized animals were significantly larger than the control at the above two time points (P < 0.001). The results demonstrate the stimulating effect of partial hepatectomy directly on the tumor growth in the liver, in contrast to previous studies on ectopic tumors. Furthermore, since conservative partial hepatectomy (30%) is normally used in clinical practice for surgical treatment of liver metastasis, the animal models presented here should be useful for the clinical investigation of the high recurrence rate of liver metastasis following partial hepatectomy.

Animals↗

An ultra-metastatic model of human colon cancer in nude mice.

An ultra-high metastatic model of human colon cancer was developed in order to represent highly malignant patient disease for which there is no current model. Surgical orthotopic implantation (SOI) of a histologically intact liver metastasis fragment derived from a surgical specimen of a patient with metastatic colon cancer was initially implanted in the colon, liver and subcutaneously in nude mice. This tumor did not metastasize for the first 10 passages. At the eleventh passage, the tumor exhibited metastasis from the colon to the liver, spleen, and lymph nodes. At this time, two selective passages were carried out by transplanting resulting liver metastases in the nude mice to the colon of additional nude mice. After these two passages, the tumor became stably ultra-metastatic and was termed AC3488UM. One-hundred percent of mice transplanted with AC3488UM with SOI to the colon exhibited local growth, regional invasion, and spontaneous metastasis to the liver, lymph nodes, and spleen. While the maximum size of the primary tumor was 0.9 g, the metastatic liver was over 9 times the weight of the normal liver with the maximum weight of the metastatic liver over 12 g. Liver metastases were detected by the tenth day after transplantation in all animals. Half the animals died of metastatic tumor 25 days after transplantation. Histological characteristics of AC3488UM tumor were poorly differentiated adenocarcinoma of colon. Mutant p53 is expressed heterogeneously in the primary tumor and more homogeneously in the liver metastasis suggesting a possible role of p53 in the liver metastasis. The human origin of AC3488UM was confirmed by positive fluorescence staining for in situ hybridization of human DNA. The AC3488 human colon-tumor model with its ultra-high metastatic capability in each transplanted animal, short latency and a short median survival period is different from any known human colon cancer model and will be an important tool for the study of and development of new therapy for highly metastatic human colon cancer.

Animals↗

Genetically fluorescent melanoma bone and organ metastasis models.

We report here the establishment and metastatic properties of bright, highly stable, green fluorescent protein (GFP) expression transductants of the B16 mouse malignant melanoma cell line and the LOX human melanoma line. The highly fluorescent malignant melanoma cell lines allowed the visualization of skeletal and multiorgan metastases after i.v. injection of B16 cells in C57BL/6 mice and intradermal injection of LOX cells in nude mice. The melanoma cell lines were transduced with the pLEIN expression retroviral vector containing the GFP and neomycin resistance genes. Stable B16F0 and LOX clones expressing high levels of GFP were selected stepwise in vitro in levels of G418 of up to 800 microg/ml. Extensive bone and bone marrow metastases of B16F0 were visualized by GFP expression when the animals were sacrificed 3 weeks after cell implantation. Metastases for both cell lines were visualized in many organs, including the brain, lung, pleural membrane, liver, kidney, adrenal gland, lymph nodes, skeleton, muscle, and skin by GFP fluorescence. This is the first observation of experimental skeletal metastases of melanoma, which was made possible by GFP expression. These models should facilitate future studies of the mechanism and therapy of bone and multiorgan metastasis of melanoma.

Animals↗

Widespread skeletal metastatic potential of human lung cancer revealed by green fluorescent protein expression.

To understand the skeletal metastatic pattern of non-small cell lung cancer, we developed a stable high-expression green fluorescent protein (GFP) transductant of human lung cancer cell line H460 (H460-GFP). The GFP-expressing lung cancer was visualized to metastasize widely throughout the skeleton when implanted orthotopically in nude mice. H460 was transduced with the pLEIN retroviral expression vector containing the enhanced GFP and the neomycin (G418) resistance gene. A stable high GFP-expressing clone was selected in vitro using 800 microg/ml G418. Stable high-level expression of GFP was maintained in s.c.-growing tumors formed after injecting H460-GFP cells in nude mice. To use H460-GFP for visualization of metastasis, fragments of s.c.-growing H460-GFP tumors were implanted by surgical orthotopic implantation in the left lung of nude mice. Subsequent micrometastases were visualized by GFP fluorescence in the contralateral lung, plural membrane, and widely throughout the skeletal system including the skull, vertebra, femur, tibia, pelvis, and bone marrow of the femur and tibia. The use of GFP-expressing H460 cells transplanted by surgical orthotopic implantation revealed the extensive metastatic potential of lung cancer in particular to widely disseminated sites throughout the skeleton. This new metastatic model can play a critical role in the study of the mechanism of skeletal and other metastasis in lung cancer and in screening of therapeutics that prevent or reverse this process.

3T3 Cells↗

Surgical orthotopic implantation allows high lung and lymph node metastatic expression of human prostate carcinoma cell line PC-3 in nude mice.

BACKGROUND: Prostate cancer is the second leading cause of male death in the United States. When diagnosed, nearly half the cases have metastatic lesions. An animal model of human prostate cancer demonstrating spontaneous metastasis from the orthotopic site after tumor implantation should be of great help for us to understand the disease and to formulate treatment strategy. We report here a high metastatic model of human prostate cancer PC-3. METHODS: We developed microsurgical techniques, termed surgical orthotopic implantation (SOI), to implant histologically intact tumor tissues orthotopically in immunodeficient mice. In this study intact tissue of the human prostate cancer cell line PC-3, harvested from a subcutaneous tumor in a nude mouse, was implanted to the ventral lateral lobes of the prostate gland in a series of nude mice. Mice were sacrificed when found moribund, and autopsy and histology were performed subsequently. RESULTS: A high frequency of lymph node and lung metastasis was noted upon histological examination. The extensive and widespread lung metastasis following orthotopic implantation of PC-3 is, to the best of our knowledge, the first report in the literature. CONCLUSIONS: In contrast to orthotopic injection of cell suspensions, no multiple metastatic cell selection was necessary after SOI for significant expression of the metastatic potential of PC-3. We conclude that the stromal tissue architecture maintained in the implanted tumor played a critical role in tumor growth and progression.

Animals↗

Mechanisms of insulin resistance in experimental hyperinsulinemic dogs.

This study was undertaken to characterize the insulin resistance and the mechanism thereof caused by chronic hyperinsulinemia produced in dogs by surgically diverting the veins of the pancreas from the portal vein to the vena cava. Pancreatic venous diversion (PVD, n = 8) caused a sustained increase in arterial insulin and decrease in portal insulin concentration compared with the control group (n = 6). Hyperinsulinemic euglycemic clamps were conducted 4 wk after surgery. The increase in the glucose disposal rate (GDR) was significantly less in the PVD group (39.0+/-5.0 vs. 27.9+/-3.2 micromol/kg/min, P < 0.01) compared with the control group, but the suppression of hepatic glucose production by insulin was similar for both groups. Muscle insulin receptor tyrosine kinase activity (IR-TKA) increased from 6.2+/-0.4 to 20.3+/-2.7 in the control group, but from 5.8+/-0.5 to only 12.7+/-1.7 fmol P/fmol IR in the PVD group (P < 0.01). With respect to the periphery, the time to half-maximum response (t1/2a) for arterial insulin was the same for both groups, whereas the t1/2a for lymph insulin (30+/-3 vs. 40+/-4 min, P < 0.05) and GDR (29+/-3 vs. 66+/-10 min, P < 0.01) were greater for the PVD group. Chronic hyperinsulinemia led to marked peripheral insulin resistance characterized by decreased insulin-stimulated GDR, and impaired activation of GDR kinetics due, in part, to reduced IR-TKA. Transendothelial insulin transport was impeded and was responsible for one third of the kinetic defect in insulin-resistant animals, while slower intracellular mechanisms of GDR were responsible for the remaining two thirds.

Animals↗

A patient-like orthotopic implantation nude mouse model of highly metastatic human ovarian cancer.

Clinically relevant animal models of human cancer are important for studies of cancer biology, invasion and metastasis, and for investigating new forms of prognostic diagnosis and therapy. An ovarian tumor line (RMG-1: human clear cell carcinoma of the ovary) previously grown subcutaneously was implanted orthotopically as intact tissue into the ovarian capsule of 22 nude mice. The tumors showed progressive growth at the orthotopic site in all animals. Tumor-associated serum galactosyltransferase (GAT) tended to be positive in all nude -mice. The tumors invaded or metastasized to the contralateral ovary, retroperitoneum, mesentery and peritoneum, and omentum, and metastasized to the subcutaneous tissue, lymph nodes and distant organs including the liver, kidney, pancreas, and diaphragm. In striking contrast, subcutaneous transplantation of this tumor resulted in growth in only 2 of 5 animals with local lymph node and kidney involvement but no retroperitoneal or peritoneal involvement. These findings suggest that orthotopic implantation provides a suitable micro-environment in which ovarian cancer can express its intrinsic clinically-relevant properties. This approach is relevant to the clinical features of ovarian cancer and is thought to be a useful model for studies of therapy for this cancer.

Adenocarcinoma, Clear Cell↗

Governing step of metastasis visualized in vitro.

Metastasis is the ultimate life-threatening stage of cancer. The lack of accurate model systems thwarted studies of the metastatic cell's basic biology. To follow continuously the succeeding stages of metastatic colony growth, we heritably labeled cells from the human lung adenocarcinoma cell line ANIP 973 with green fluorescent protein (GFP) by transfection with GFP cDNA. Labeled cells were then injected intravenously into nude mice, where, by 7 days, they formed brilliantly fluorescing metastatic colonies on mouse lung [Chishima, T., Miyagi, Y., Wang, X., Yang, M., Tan, Y., Shimada, H., Moossa, A. R. & Hoffman, R. M. (1997) Clin. Exp. Metastasis 15, 547-552]. The seeded lung tissue was then excised and incubated in the three-dimensional sponge-gel-matrix-supported histoculture that maintained the critical features of progressive in vivo tumor colonization while allowing continuous access for measurement and manipulation. Tumor progression was continuously visualized by GFP fluorescence in the same individual cultures over a 52-day period, during which the tumors spread throughout the lung. Histoculture tumor colonization was selective for lung cancer cells to grow on lung tissue, because no growth occurred on histocultured mouse liver tissue, which was also observed in vivo. The ability to support selective organ colonization in histoculture and visualize tumor progression by GFP fluorescence allows the in vitro study of the governing processes of metastasis [Kuo, T.-H., Kubota, T., Watanbe, M., Furukawa, T., Teramoto, T., Ishibiki, K., Kitajima, M., Moossa, A. R., Penman, S. & Hoffman, R. M. (1995) Proc. Natl. Acad. Sci. USA 92, 12085-12089]. The results presented here provide significant, new opportunities to understand and to develop treatments that prevent and possibly reverse metastasis.

Adenocarcinoma↗

Cancer invasion and micrometastasis visualized in live tissue by green fluorescent protein expression.

We report the establishment of stable, high-level green fluorescent protein (GFP)-expressing cell lines in vitro that permit the detection and visualization of distant micrometastases when they are implanted orthotopically in nude mice. Chinese hamster ovary cells were transfected with the dicistronic expression vector containing the humanized GFP cDNA. A stable GFP-expressing clone was selected in 1.5 microM methotrexate in vitro and injected s.c. in nude mice. Stable high-level expression of GFP was maintained in the s.c. growing tumors. To use GFP expression for metastasis studies, fragments of s.c. growing tumor, which are comprised of GFP-expressing cells, were implanted by surgical orthotopic implantation in the ovary of nude mice. Subsequent micrometastases were detected in systemic organs and could be visualized by GFP fluorescence in the lung, liver, and other organs down to the single-cell level. With this fluorescent tool, we detected and visualized for the first time tumor cells at the microscopic level in fresh viable tissue in their normal host organ. Confocal microscopy further enabled us to study physiologically relevant patterns of invasion and micrometastasis.

Animals↗

Metastatic patterns of lung cancer visualized live and in process by green fluorescence protein expression.

We demonstrate here the visualization of human lung cancer metastasis live and in process in nude mice by green fluorescent protein (GFP) expression. The human lung adenocarcinoma cell line Anip 973 stably transfected with the humanized GFP-S65T cDNA was selected for very bright green fluorescence. GFP-transfected lung cancer cells were initially inoculated subcutaneously in nude mice. Five weeks after transplantation, the resulting tumor had reached over 1 cm in diameter and had very bright GFP fluorescence. Fragments of subcutaneous tumor were implanted onto the visceral pleura of the left lung of nude mice by surgical orthotopic implantation (SOI) of histologically-intact tissue via transverse thoracotomy. The ipsilateral resulting tumor was highly fluorescent due to GFP expression. GFP expression allowed the visualization of the advancing margin of the ipsilateral tumor into the fresh normal lung tissue. Lymphogenous and direct-seeding metastases in the pulmonary hilum, cervical lymph nodes, the mediastinum and contralateral pleural cavity and contralateral lung in the SOI-treated mice were brightly visualized by GFP expression in fresh tissue. GFP-transfected and untransfected tumor had similar metastatic characteristics suggesting that GFP expression had no effect on metastasis itself. The results with the GFP-transfected tumor cells, combined with the use of SOI, demonstrate a fundamental advance in the visualization and study of lung cancer metastasis in process.

Adenocarcinoma↗