[Prognostic significance of lysosomal cysteine proteases in the estimation of the effectiveness of the antitumorigenic therapy]

The influence of the untitumor drugs, cyclophosphamide (CPA) and nitrosomethylurea (NMM) on the activity of lysosomal cysteine proteases cathepsin B and L in the tumor tissue was studied. Regression or reduction in the rate of growth of LS and RLS (drug sensitive and resistant sarcomas, respectively) during injection of CPA or NMM was accompanied by the increase in the activity of cysteine proteases cathepsin B and L in the tumor tissue. The increase of cathepsin B and L activity in the tumor tissue was correlated with the therapeutic effect of the used drugs. Data obtained suggest that cathepsin B and L activity in the tumor tissue have a prognostic significance for the effectiveness of antitumor therapy.

15-Hydroxyprostaglandin dehydrogenase suppresses K-RasV12-dependent tumor formation in Nu/Nu mice

Oncogenic Ras mutations are early genetic events in colorectal cancer that induce cyclooxygenase (COX)-2 expression and prostaglandin E(2) (PGE(2)) biosynthesis. PGE(2), a downstream product of COX-2, promotes cancer progression by modulating proliferation, apoptosis and angiogenesis. 15-hydroxyprostaglandin dehydrogenase (PGDH) degrades PGE(2) and is down-regulated in colorectal cancer, suggesting that PGDH plays a role in regulating PGE(2) levels and that PGDH over-expression could attenuate Ras-mediated tumorigenesis. Lentiviral transduction was used to express GFP (18.GFP), K-Ras(V12) (18.K-Ras(V12)), PGDH (18.PGDH) or both K-Ras(V12) and PGDH (18.K-Ras(V12).PGDH) in nontumorigenic rat intestinal epithelial (IEC-18) cells. 18.K-Ras(V12) cells exhibited increased phosphorylation of MAP kinases and CREB, proliferation rates, COX-2 and microsomal prostaglandin E synthase (mPGES)-1 expression and PGE(2) and PGI(2) levels. 18.PGDH and 18.K-Ras(V12).PGDH cells had 10(4)-fold increases in PGDH activity with decreased PGE(2) and PGI(2) levels, COX-2 and mPGES-1 expression and proliferation rates. 18.GFP, 18.PGDH, and 18.K-Ras(V12).PGDH cells were unable to grow in soft agar media whereas 18.K-Ras(V12) cells exhibited anchorage-independent cell growth. Xenografts of implanted 18.K-Ras(V12) cells in nu/nu mice produced rapid (2 wk) tumors with uniform antibody staining for COX-2 and mPGES-1 throughout the tumor and elevated PGE(2) levels. Xenografts of 18.K-Ras(V12).PGDH cells exhibited delayed (8 wk) tumor formation with negligible COX-2 and mPGES-1 expression and significantly decreased PGE(2) levels. 18.K-Ras(V12).PGDH tumors had decreased staining of the proliferative marker, Ki-67, and a significant increase in apoptosis in the central region of the tumor. Based on these data, we conclude that PGDH expression suppresses K-Ras(V12)-mediated tumorigenesis in intestinal epithelial cells.

Anticancer activity of RecQL1 helicase siRNA in mouse xenograft models

Small interfering RNAs (siRNAs) are expected to have a medical application in human therapy as drugs with a high specificity for their molecular target mRNAs. RecQL1 DNA helicase in the human RecQ helicase family participates in DNA repair and recombination pathways in the cell cycle of replication. Silencing the RecQL1 expression by RecQL1-siRNA induces mitotic death in vitro specifically in growing cancer cells. By contrast, the same RecQL1 silencing does not affect the growth of normal cells, emphasizing that RecQL1 helicase is an ideal molecular target for cancer therapy. In this study, we show that local and systemic administration of RecQL1-siRNA mixed with polyethyleneimine polymer or cationic liposomes prevented cancer cell proliferation in vivo in mouse models of cancer without noticeable adverse effects. The results indicate that RecQL1-siRNA in a complex with a cationic polymer is a very promising anticancer drug candidate, and that in particular, RecQL1-siRNA formulated with a cationic liposome has an enormous potential to be used by intravenous injection for therapy specific for liver cancers, including metastasized cancers from the colon and pancreas.

Matrix metalloproteinase-9 is required for tumor vasculogenesis but not for angiogenesis: role of bone marrow-derived myelomonocytic cells

Tumor vasculature is derived from sprouting of local vessels (angiogenesis) and bone marrow (BM)-derived circulating cells (vasculogenesis). By using a model system of transplanting tumors into an irradiated normal tissue to prevent angiogenesis, we found that tumors were unable to grow in matrix metalloproteinase-9 (MMP-9) knockout mice, but tumor growth could be restored by transplantation of wild-type BM. Endothelial progenitor cells did not contribute significantly to this process. Rather, CD11b-positive myelomonocytic cells from the transplanted BM were responsible for tumor growth and the development of immature blood vessels in MMP-9 knockout mice receiving wild-type BM. Our results suggest that MMP-9 could be an important target for adjunct therapy to enhance the response of tumors to radiotherapy.

A catalytic role for proangiogenic marrow-derived cells in tumor neovascularization

Small numbers of proangiogenic bone marrow-derived cells (BMDCs) can play pivotal roles in tumor progression. In this issue of Cancer Cell, two papers, utilizing different tumor angiogenesis models, both find that activated MMP-9 delivered by BMDCs modulates neovessel remodeling, thereby promoting tumor growth. The changes in microvascular anatomy induced by MMP-9-expressing BMDCs are strikingly different between the preirradiated tumor vascular bed model employed by Ahn and Brown and the invasive glioblastoma model utilized by Du et al., likely mirroring the complexity of the real tumor microenvironment and the intricacy of roles of different BMDC populations in mediating tumor neoangiogenesis.

[Histone specific proteinase and DNase activity of spleen lymphocyte nuclei during oncogenesis and under the effect of hydrobromide-5-(5',6' benzocoumaroyl-3')-methylaminouracil]

The features of histone proteolysis, their carbonylation level and endonucleolysis intensity were studied in the spleen lymphocytes of rats with transplanted Guerin's carcinoma and under the conditions of hydrobromide-5-(5',6' benzocoumaroyl-3')-methylaminouracil (BCU) action. The intensification of oxidizing histone destruction and histone-specific protease activity during oncogenesis and under conditions of BCU action was shown. DNase I and DNase II enzymatic activities of spleen lymphocytes of rats with tumour were decreased on different stages of tumour development, however, they were increased under conditions of chemical compound administration.

Hypoxia-inducible expression of the mouse carbonic anhydrase IX demonstrated by new monoclonal antibodies

CA IX is a transmembrane carbonic anhydrase isoenzyme predominantly expressed in human tumors in response to hypoxia and functionally implicated in adaptation of tumor cells to hypoxic stress via control of pH and cell adhesion. Intense investigations of the human CA IX as a hypoxic marker and a therapeutic target have been facilitated by specific monoclonal antibodies. However, no such reagents existed for the mouse CA IX ortholog. We generated five new anti-mouse CA IX monoclonal antibodies AM1-4, AM4-3, AM27-4, AM34-7 and AM35-1 produced using CA IX-deficient mice. The antibodies are suitable for various immunodetection methods including immunoblotting and immunohistochemistry. Using these reagents we show that the mouse CA IX is expressed in three out of nine tested mouse cell lines, namely in L929, MEF and TSA and is regulated by hypoxia and cell density similarly to human CA IX. We also demonstrate that the mouse CA IX exhibits hypoxia-related expression pattern in multicellular spheroids and in tumor xenografts. Our results indicate the use of the mouse model as suitable for further studies of CA IX role in tumor development and for its pre-clinical investigations. The new monoclonal antibodies represent potent tools for accomplishment of these future studies.

Apple procyanidins induce tumor cell apoptosis through mitochondrial pathway activation of caspase-3

Various epidemiologic and experimental in vivo and in vitro studies have suggested that polyphenols derived from fruits, vegetables and beverages might decrease the risk of developing lifestyle diseases, such as cardiovascular disorders and cancer. Apples are a major dietary source of polyphenols. Here we investigated the antitumor activity of apple polyphenols (APs) and procyanidins, namely condensed tannins, both in vitro and in vivo studies. APs and procyanidins inhibited the growth of transplanted B16 mouse melanoma cells and BALB-MC.E12 mouse mammary tumor cells, and increased the survival rate of the host mice-transplanted B16 cells. Among the APs, the apple procyanidins specifically, rather than other polyphenols such as chlorogenic acid, (-)-epicatechin, phloridzin and procyanidin B2, had a major effect on cell proliferation and induced apoptosis in vitro. The apple procyanidins increased mitochondrial membrane permeability and cytochrome c release from mitochondria and activated caspase-3 and caspase-9 within the tumor cells. In addition, we separated eight procyanidin fractions according to the degree of polymerization using normal-phase chromatography, and detected strong anti-tumor activity in the procyanidin pentamer and higher degree fractions. Our results indicate that the oral administration of apple procyanidins inhibits the proliferation of tumor cells by inducing apoptosis through the intrinsic mitochondrial pathway.

The expression level of luciferase within tumour cells can alter tumour growth upon in vivo bioluminescence imaging

In vivo bioluminescence imaging is becoming a very important tool for the study of a variety of cellular and molecular events or disease processes in living systems. In vivo bioluminescence imaging is based on the detection of light emitted from within an animal. The light is generated as a product of the luciferase-luciferin reaction taking place in a cell. In this study, we implanted mice with tumour cells expressing either a high or a low level of luciferase. In vivo bioluminescence imaging was used to follow tumour progression. Repeated luciferin injection and imaging of high and low luciferase-expressing tumours was performed. While low luciferase-expressing tumours grew similarly to vector controls, growth of the high luciferase-expressing tumours was severely inhibited. The observation that a high level of luciferase expression will inhibit tumour cell growth when an animal is subjected to serial in vivo bioluminescence imaging is potentially an important factor in designing these types of studies.

Stroma-derived matrix metalloproteinase (MMP)-2 promotes membrane type 1-MMP-dependent tumor growth in mice

Matrix metalloproteinase-2 (MMP-2) is a stroma-derived MMP belonging to the type IV collagenase family. It is believed to mediate tumor cell behavior by degrading deposits of type IV collagen, a major component of the basement membrane. The membrane type 1-MMP (MT1-MMP) is a highly potent activator of MMP-2 and is expressed in many tumor and stromal cells. However, the roles played by stromal MMP-2 in tumor progression in vivo remain poorly understood. We established a colon epithelial cell line from an Mt1-mmp(-/-) mouse strain and transfected these cells with an inducible expression system for MT1-MMP (MT1rev cells). Following s.c. implantation into Mmp-2(+/+) mice and induction of MT1-MMP expression, MT1rev cells grew rapidly, whereas they grew very slowly in Mmp-2(-/-) mice, even in the presence of MT1-MMP. This MT1-MMP-dependent tumor growth of MT1rev cells was enhanced in Mmp-2(-/-) mice as long as MMP-2 was supplied via transfection or coimplantation of MMP-2-positive fibroblasts. MT1rev cells cultured in vitro in a three-dimensional collagen gel matrix also required the MT1-MMP/MMP-2 axis for rapid proliferation. MT1rev cells deposit type IV collagen primarily at the cell-collagen interface, and these deposits seem scarce at sites of invasion and proliferation. These data suggest that cooperation between stroma-derived MMP-2 and tumor-derived MT1-MMP may play a role in tumor invasion and proliferation via remodeling of the tumor-associated basement membrane. To our knowledge, this is the first study demonstrating that MT1-MMP-dependent tumor growth in vivo requires stromal-derived MMP-2. It also suggests that MMP-2 represents a potential target for tumor therapeutics.

Influence of tumor cell and stroma sensitivity on tumor response to radiation

In this study, we evaluated the role of tumor cell and tumor stroma sensitivity as determinants of radiation-induced tumor growth delay. A DNA double-strand break repair-defective DNA-PKcs(-/-) tumor cell line and its radioresistant DNA-PKcs(+/+)-transfected counterpart were used to initiate tumors in nude and hypersensitive severe combined immunodeficient (SCID) mice. Insertion of the human DNA-PKcs(+/+) gene substantially increased the intrinsic radioresistance of the DNA-PKcs(-/-) tumor cells and substantially decreased tumor response to radiation in both nude and hypersensitive SCID mice. Tumor cell radiosensitivity was the major determinant of tumor response in nude mice. In SCID mice, both tumor cell sensitivity and radiation-induced stromal damage contributed to response. The relative contribution of host and tumor cell sensitivity on tumor response was unchanged for single doses of 1 x 15 and 6 x 3 Gy-fractionated dose irradiation.

Antitumor and antimetastatic activity of fucoidan, a sulfated polysaccharide isolated from the Okhotsk Sea Fucus evanescens brown alga

Antitumor and antimetastatic activities of fucoidan, a sulfated polysaccharide isolated from Fucus evanescens (brown alga in Okhotsk sea), was studied in C57Bl/6 mice with transplanted Lewis lung adenocarcinoma. Fucoidan after single and repeated administration in a dose of 10 mg/kg produced moderate antitumor and antimetastatic effects and potentiated the antimetastatic, but not antitumor activities of cyclophosphamide. Fucoidan in a dose of 25 mg/kg potentiated the toxic effect of cyclophosphamide.

Expression of Tie-2 by Human Monocytes and Their Responses to Angiopoietin-2

Angiopoietins 1 and 2 bind to Tie-2 expressed on endothelial cells and regulate vessel stabilization and angiogenesis. Tie-2(+) monocytes have been shown to be recruited to experimental tumors where they promote tumor angiogenesis. In this study, we show that 20% of CD14(+) human blood monocytes express Tie-2, and that these cells coexpress CD16 (FcgammaRIII) and are predominantly CD34 negative. Ang-2 is up-regulated by endothelial cells in malignant tumors and inflamed tissues, so our finding that Ang-2 is a chemoattractant for human Tie-2(+) monocytes and macrophages, suggests that it may help to recruit and regulate their distribution in such tissues. Ang-2 was also found to markedly inhibit release of the important proinflammatory cytokine, TNF-alpha, by monocytes in vitro. Following extravasation of monocytes, and their differentiation into macrophages, many accumulate in the hypoxic areas of inflamed and malignant tissues. Ang-2 is known to be up-regulated by hypoxia and we show that monocytes and macrophages up-regulate Tie-2 when exposed to hypoxia. Furthermore, hypoxia augmented the inhibitory effect of Ang-2 on the release of the anti-angiogenic cytokine, IL-12 by monocytes. In sum, our data indicate that Ang-2 may recruit Tie-2(+) monocytes to tumors and sites of inflammation, modulate their release of important cytokines and stimulate them to express a proangiogenic phenotype.

Role of MGMT in protecting against cyclophosphamide-induced toxicity in cells and animals

O(6)-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that protects cells from the biological consequences of alkylating agents by removing alkyl groups from the O(6)-position of guanine. Cyclophosphamide and ifosfamide are oxazaphosphorines used clinically to treat a wide variety of cancers; however, the role of MGMT in recognizing DNA damage induced by these agents is unclear. In vitro evidence suggests that MGMT may protect against the urotoxic oxazaphosphorine metabolite, acrolein. Here, we demonstrate that Chinese hamster ovary cells transfected with MGMT are protected against cytotoxicity following treatment with chloroacetaldehyde (CAA), a neuro- and nephrotoxic metabolite of cyclophosphamide and ifosfamide. The mechanism by which MGMT recognizes damage induced by acrolein and CAA is unknown. CHO cells expressing a mutant form of MGMT (MGMT(R128A)), known to have >1000-fold less repair activity towards alkylated DNA while maintaining full active site transferase activity towards low molecular weight substrates, exhibited equivalent CAA- and acrolein-induced cytotoxicity to that of CHO cells transfected with plasmid control. These results imply that direct reaction of acrolein or CAA with the active site cysteine residue of MGMT, i.e. scavenging, is unlikely a mechanism to explain MGMT protection from CAA and acrolein-induced toxicity. In vivo, no difference was detected between Mgmt-/- and Mgmt+/+ mice in the lethal effects of cyclophosphamide. While MGMT may be important at the cellular level, mice deficient in MGMT are not significantly more susceptible to cyclophosphamide, acrolein or CAA. Thus, our data does not support targeting MGMT to improve oxazaphosphorine therapy.

Genetic alteration of endothelial heparan sulfate selectively inhibits tumor angiogenesis

To examine the role of endothelial heparan sulfate during angiogenesis, we generated mice bearing an endothelial-targeted deletion in the biosynthetic enzyme N-acetylglucosamine N-deacetylase/N-sulfotransferase 1 (Ndst1). Physiological angiogenesis during cutaneous wound repair was unaffected, as was growth and reproductive capacity of the mice. In contrast, pathological angiogenesis in experimental tumors was altered, resulting in smaller tumors and reduced microvascular density and branching. To simulate the angiogenic environment of the tumor, endothelial cells were isolated and propagated in vitro with proangiogenic growth factors. Binding of FGF-2 and VEGF(164) to cells and to purified heparan sulfate was dramatically reduced. Mutant endothelial cells also exhibited altered sprouting responses to FGF-2 and VEGF(164), reduced Erk phosphorylation, and an increase in apoptosis in branching assays. Corresponding changes in growth factor binding to tumor endothelium and apoptosis were also observed in vivo. These findings demonstrate a cell-autonomous effect of heparan sulfate on endothelial cell growth in the context of tumor angiogenesis.

Heparanase Enhances Syndecan-1 Shedding

When shed from the cell surface, the heparan sulfate proteoglycan syndecan-1 can facilitate the growth, angiogenesis, and metastasis of tumors. Here we report that tumor cell expression of heparanase, an enzyme known to be a potent promoter of tumor progression and metastasis, regulates both the level and location of syndecan-1 within the tumor microenvironment by enhancing its synthesis and subsequent shedding from the tumor cell surface. Heparanase regulation of syndecan-1 is detected in both human myeloma and breast cancer cell lines. This regulation requires the presence of active enzyme, because mutated forms of heparanase lacking heparan sulfate-degrading activity failed to influence syndecan-1 expression or shedding. Removal of heparan sulfate from the cell surface using bacterial heparitinase dramatically accelerated syndecan-1 shedding, suggesting that the effects of heparanase on syndecan-1 expression by tumor cells may be due, at least in part, to enzymatic removal or reduction in the size of heparan sulfate chains. Animals bearing tumors formed from cells expressing high levels of heparanase or animals transgenic for heparanase expression exhibited elevated levels of serum syndecan-1 as compared with controls, indicating that heparanase regulation of syndecan-1 expression and shedding can occur in vivo and impact cancer progression and perhaps other pathological states. These results reveal a new mechanism by which heparanase promotes an aggressive tumor phenotype and suggests that heparanase and syndecan-1 act synergistically to fine tune the tumor microenvironment and ensure robust tumor growth.

Histone deacetylase (HDAC) inhibitor LBH589 increases duration of gamma-H2AX foci and confines HDAC4 to the cytoplasm in irradiated non-small cell lung cancer

Histone deacetylases (HDAC) have been identified as therapeutic targets due to their regulatory function in DNA structure and organization. LBH589 is a novel inhibitor of class I and II HDACs. We studied the effect of LBH589 and ionizing radiation (IR) on DNA repair in two human non-small cell lung cancer (NSCLC) cell lines (H23 and H460). gamma-H2AX foci present at DNA double-strand breaks (DSBs) were detected in the nuclei following 3 Gy irradiation for up to 6 hours. LBH589 administered before irradiation increased the duration of gamma-H2AX foci beyond 24 hours. Furthermore, radiation alone induced translocation of HDAC4 to the nucleus. In contrast, treatment with LBH589 followed by irradiation resulted in HDAC4 confinement to the cytoplasm, indicating that HDAC inhibition affects the nuclear localization of HDAC4. The findings that LBH589 confines HDAC4 to the cytoplasm and increases the duration of gamma-H2AX foci in irradiated cell lines suggest that HDAC4 participates in DNA damage signaling following IR. Annexin-propidium iodide flow cytometry assays, cell morphology studies, and cleaved caspase-3 Western blot analysis revealed a synergistic effect of LBH589 with IR in inducing apoptosis. Clonogenic survival showed a greater than additive effect when LBH589 was administered before irradiation compared with irradiation alone. In vivo tumor volume studies showed a growth delay of 20 days with combined treatment compared with 4 and 2 days for radiation or LBH589 alone. This study identifies HDAC4 as a biomarker of LBH589 activity and recognizes the ability of LBH589 to sensitize human NSCLC to radiation-induced DNA DSBs.

Activation of a novel Bcr/Abl destruction pathway by WP1130 induces apoptosis of chronic myelogenous leukemia cells

Imatinib mesylate (Gleevec) is effective therapy against Philadelphia chromosome-positive leukemia, but resistance develops in all phases of the disease. Bcr/Abl point mutations and other alterations reduce the kinase inhibitory activity of imatinib mesylate; thus, agents that target Bcr/Abl through unique mechanisms may be needed. Here we describe the activity of WP1130, a small molecule that specifically and rapidly down-regulates both wild-type and mutant Bcr/Abl protein without affecting bcr/abl gene expression in chronic myelogenous leukemia (CML) cells. Loss of Bcr/Abl protein correlated with the onset of apoptosis and reduced phosphorylation of Bcr/Abl substrates. WP1130 did not affect Hsp90/Hsp70 ratios within the cells and did not require the participation of the proteasomal pathway for loss of Bcr/Abl protein. WP1130 was more effective in reducing leukemic versus normal hematopoietic colony formation and strongly inhibited colony formation of cells derived from patients with T315I mutant Bcr/Abl-expressing CML in blast crisis. WP1130 suppressed the growth of K562 heterotransplanted tumors as well as both wild-type Bcr/Abl and T315I mutant Bcr/Abl-expressing BaF/3 cells transplanted into nude mice. Collectively, our results demonstrate that WP1130 reduces wild-type and T315I mutant Bcr/Abl protein levels in CML cells through a unique mechanism and may be useful in treating CML.

Anti-cancer activities of pure curry feeding in cancer cell-transplanted mouse

To confirm the cytotoxic effect of instant curry containing combined spices on cancer cells in vivo, cancer was induced by transplanting cancer cells to mice, and the development of cancer upon feeding pure curry were examined. The concentration of lipid peroxide in the groups transplanted with cancer cells which were fed with normal feed was 19.6 nM, and it was increased as the amount of pure curry was increased. The concentration of cytochrome P-450 was decreased in the group transplanted with cancer cells which were fed with pure curry and the group without the transplant which were fed with pure curry when compared with the groups which were fed with normal feed. The activity of cytochrome P-450 was decreased as the concentration of cytochrome P-450 was decreased in the groups transplanted with cancer cells. However, it was increased in the groups without cancer cell transplant when over 2% of pure curry was fed. The amount of glutathione was increased in the groups transplanted with cancer cells when over 2% of pure curry was fed. The activities of glutathione peroxidase and glutathione S-transferase were decreased in the groups transplanted with cancer cells which were fed with over 1% of pure curry, and were restored to the level of the group without cancer cell transplant which were fed with normal feed. The superoxide dismutase activity in the groups transplanted with cancer cells was restored to the level of the group without cancer cell transplant which was fed with normal feed when over 1% of pure curry was fed.

Metastatic ability of Drosophila tumors depends on MMP activity

We analyzed how cells from tumors caused by mutations in either lgl or brat use matrix metalloproteinases (MMPs) to facilitate metastasis in Drosophila. MMP1 accumulation is dramatically increased in lgl larval imaginal discs compared to both wild type and brat mutants. Removal of Mmp1 gene activity in lgl brain tumor cells reduced their frequency of ovarian micro-metastases after transplantation; whereas, removal of Mmp1 gene activity in brat tumor cells had no such effect. Host ovaries showed increased Mmp1 gene expression in response to transplantation of brat tumors but not of lgl tumors. Reduction of MMP activity in host ovaries by ectopic expression of TIMP significantly reduced both lgl and brat metastases in that organ. These results highlight the mechanisms that lgl and brat tumor cells use to metastasize. Our interpretation of these data is that secretion of MMP1 from lgl tumor cells facilitates their metastasis, while secretion of MMP1 from host ovaries facilitates brat tumor metastasis. This study is the first demonstration that Drosophila tumors utilize MMP activity to metastasize.

Tumor epithelial cell matrix metalloproteinase 9 is a target for antimetastatic therapy in colorectal cancer

BACKGROUND

The current paradigm suggests that matrix metalloproteinase 9 (MMP-9) expressed by stromal cells is a therapeutic target in human colorectal tumors which presumably regulates metastatic disease progression. Conversely, whereas cancer cells within those tumors may induce stromal cells to produce MMP-9 and may be targets for MMP-9 activity, they are not the source of MMP-9 underlying metastasis.

METHODS

MMP-9 expression in matched colorectal tumors and normal adjacent mucosa from patients and human colon cancer cell lines was examined by real-time reverse transcription-PCR, laser capture microdissection, immunoelectron microscopy, and immunoblot analysis. The role of colon cancer cell MMP-9 in processes underlying metastasis was explored in vitro by examining degradation of extracellular matrix components by gelatin zymography and formation of locomotory organelles by cell spreading analysis and in vivo by quantifying hematogenous tumor cell seeding of mouse lungs.

RESULTS

Primary colorectal tumors overexpress MMP-9 compared with matched normal adjacent mucosa. In contrast to the current paradigm, MMP-9 is expressed equally by cancer and stromal cells within human colon tumors. Cancer cell MMP-9 regulates metastatic behavior in vitro, including degradation of extracellular matrix components and formation of locomotory organelles. Moreover, this MMP-9 critically regulates hematogenous seeding of mouse lungs by human colon cancer cells in vivo.

CONCLUSIONS

These observations reveal that MMP-9 produced by human colon cancer, rather than stromal, cells is central to processes underlying metastasis. They underscore the previously unrecognized potential of specifically targeting tumor cell MMP-9 in interventional strategies to reduce mortality from metastatic colorectal cancer.

Outgrowth of a transformed cell population derived from normal human BM mesenchymal stem cell culture

BACKGROUND

Human mesenchymal stem cells (hMSC) have been isolated and characterized extensively for a variety of clinical applications. Yet it is unclear how the phenomenon of hMSC plasticity can be safely and reasonably exploited for therapeutic use.

METHODS

We have generated mesenchymal stem cells (MSC) from normal human BM and identified a novel cell population with a transformed phenotype. This cell population was characterized by morphologic, immunophenotypic, cytogenetic analyzes and telomerase expression. Its tumorigenicity in NOD/SCID mice was also studied.

RESULTS

A subpopulation of cells in hMSC culture was noted to appear morphologically distinct from typical MSC. The cells were spherical, cuboidal to short spindle in shape, adherent and exhibited contact independent growth. Phenotypically the cells were CD133(+), CD34(-), CD45(-), CD90(low), CD105(-), VEGFR2(+). Cytogenetic analysis showed chromosome aneuploidy and translocations. These cells also showed a high level of telemerase activity compared with typical MSC. Upon transplantation into NOD/SCID mice, multiple macroscopic solid tumors formed in multiple organs or tissues. Histologically, these tumors were very poorly differentiated and showed aggressive growth with large areas of necrosis.

DISCUSSION

The possible explanations for the origin of this cell population are: (1) the cells represent a transformed population of MSC that developed in culture; (2) abnormal cells existed in the donor BM at rare frequency and subsequently expanded in culture. In either case, the MSC culture may provide a suitable environment for transformed cells to expand or propagate in vitro. In summary, our data demonstrate the potential of transformed cells in hMSC culture and highlight the need for karyotyping as a release criteria for clinical use of MSC.

[Effect of liposomal antitumor preparation 5-(5',6'-benzocoumarin-3')-methylaminouracil hydrobromide on cytochrome P-450 in the microsomal liver fraction of tumor bearing rats]

Cytochrome P-450 thermal inactivation rate, and content of protein sulfhydryl groups and cytochrome P-450 in the microsomal liver fraction of rats at different stages of Huerin's carcinoma growth were investigated. Liposomal form of BCU administration on the background of preliminary (for 2 hours) administration of phosphatidylcholine liposomes suspension was performed. The low level of cytochrome P-450, protein SH-groups in microsomal liver fraction and increase of the rate of transition of microsomal cytochrome P-450 in P-420 was shown in the dynamics of Huerin's carcinoma growth in an organism. Low microsomal cytochrome P-450 distraction was shown in the rat liver under conditions of antitumor liposomal preparation BCU injection on the 21st day after the transplantation of Huerin's carcinoma. At the same time nonliposomal BCU caused the opposite effect. The preliminary administration of phosphatidylcholine liposomes favours the approach of the investigated parameters to the control values on the terminal stages of tumour growth.

Perk-dependent translational regulation promotes tumor cell adaptation and angiogenesis in response to hypoxic stress

It has been well established that the tumor microenvironment can promote tumor cell adaptation and survival. However, the mechanisms that influence malignant progression have not been clearly elucidated. We have previously demonstrated that cells cultured under hypoxic/anoxic conditions and transformed cells in hypoxic areas of tumors activate a translational control program known as the integrated stress response (ISR). Here, we show that tumors derived from K-Ras-transformed Perk(-/-) mouse embryonic fibroblasts (MEFs) are smaller and exhibit less angiogenesis than tumors with an intact ISR. Furthermore, Perk promotes a tumor microenvironment that favors the formation of functional microvessels. These observations were corroborated by a microarray analysis of polysome-bound RNA in aerobic and hypoxic Perk(+/+) and Perk(-/-) MEFs. This analysis revealed that a subset of proangiogenic transcripts is preferentially translated in a Perk-dependent manner; these transcripts include VCIP, an adhesion molecule that promotes cellular adhesion, integrin binding, and capillary morphogenesis. Taken with the concomitant Perk-dependent translational induction of additional proangiogenic genes identified by our microarray analysis, this study suggests that Perk plays a role in tumor cell adaptation to hypoxic stress by regulating the translation of angiogenic factors necessary for the development of functional microvessels and further supports the contention that the Perk pathway could be an attractive target for novel antitumor modalities.