Transforming growth factor beta and the cell surface in tumor progression

Parallels between hematopoietic stem cell and prostate cancer disseminated tumor cell regulation

The bone marrow is the primary site of hematopoiesis and the home for hematopoietic stem cells (HSCs) in adult mammals. Prostate cancer commonly metastasizes to the bone and forms bone metastases in almost all patients who die of the disease. Prostate cancer bone metastases are thought to develop after rare bone marrow disseminated tumor cells (DTCs) escape a dormant state and reactivate. Prostate cancer DTCs and normal HSCs have been shown to compete for residence in the bone marrow and share many of same regulatory mechanisms for survival, proliferation and homing. In this review, we highlight these parallels in order to help our readers use the literature in HSC and DTC biology to inform their research and generate hypotheses in both fields.

Pulse-modulated second harmonic imaging microscope quantitatively demonstrates marked increase of collagen in tumor after chemotherapy

Pulse-modulated second harmonic imaging microscopes (PM-SHIMs) exhibit improved signal-to-noise ratio (SNR) over conventional SHIMs on sensitive imaging and quantification of weak collagen signals inside tissues. We quantify the spatial distribution of sparse collagen inside a xenograft model of human acute myeloid leukemia (AML) tumor specimens treated with a new drug against receptor tyrosine kinase (ABT-869), and observe a significant increase in collagen area percentage, collagen fiber length, fiber width, and fiber number after chemotherapy. This finding reveals new insights into tumor responses to chemotherapy and suggests caution in developing new drugs and therapeutic regimens against cancers.

Regulation of Extracellular Matrix Remodeling following Transforming Growth Factor-β1/Epidermal Growth Factor-Stimulated Epithelial-Mesenchymal Transition in Human Premalignant Keratinocytes

During tumor progression, malignant cells exploit critical developmental and tissue remodeling programs, often promoting a plastic phenotype referred to as an epithelial-mesenchymal transition (EMT). Autocrine/paracrine signaling due to tumor microenvironment cytokines, such as members of the transforming growth factor-beta (TGF-beta) and epidermal growth factor (EGF) families, largely regulates the morphological and invasive phases of the EMT phenotype. Notably, epithelial cell initiation often coincides with a switch in the response of these cells to TGF-beta and is concomitant with EGF receptor amplification. Modeling these events, we have observed that premalignant human keratinocytes, HaCaTs, acquire a highly motile and scattered phenotype indicative of EMT following stimulation with TGF-beta1 and EGF. TGF-beta1 and EGF have been shown to upregulate a number of matrix metalloproteinases (MMP) in epithelial cells, which may in turn play a role in developing metastatic potential in these cells. We have established that an increase in MMP-10 expression occurs following treatment of HaCaT cells with a combination of TGF-beta1 and EGF. This increase in MMP-10 expression paralleled the development of a collagenolytic phenotype that was sensitive to components of the plasminogen activation system, including the plasminogen activator inhibitor type-1 (PAI-1). Significantly high levels of MMP-10 have been detected in squamous cell carcinomas of the head and neck, esophagus, oral cavity and skin. Importantly, TGF-beta1 in addition to upregulating MMP-10 has been shown to upregulate PAI-1 expression in HaCaT cells. Taken together, these observations suggest that TGF-beta1 and EGF play a complex role in modulating proteolytic and transitional events such as EMT that may facilitate the progression of human premalignant epithelial cells toward a more invasive phenotype.

PAI-1 is a Critical Upstream Regulator of the TGF-beta1/EGF-Induced Invasive Phenotype in Mutant p53 Human Cutaneous Squamous Cell Carcinoma

The emergence of highly aggressive subtypes of human cutaneous squamous cell carcinoma (SCC) often reflects increased autocrine/paracrine TGF-β synthesis and epidermal growth factor receptor (EGFR) amplification. Cooperative TGF-β/EGFR signaling promotes cell migration and induces expression of both proteases and protease inhibitors that regulate stromal remodeling resulting in acquisition of an invasive phenotype. TGF-β1+EGF stimulation increases the production of several matrix metalloproteinases (MMPs) in human SCC. Among the most prominent is MMP-10 which is known to be elevated in SCC in situ. Activation of stromal plasminogen appears to be critical in triggering downstream MMP activity. Paradoxically, PAI-1, the major physiological inhibitor of plasmin generation, is also up-regulated under these conditions and is an early event in progression of incipient epidermal SCC. A model is proposed in which TGF-β1+EGF-dependent MMP-10 elevation directs focalized matrix remodeling events that promote epithelial cell plasticity and tissue invasion. Increased PAI-1 expression serves to temporally and spatially modulate plasmin-initiated pericellular proteolysis, further facilitating epithelial invasive potential. Defining the complex signaling mechanisms that maintain this elegant balance is critical to developing potential therapeutics for the treatment of human cutaneous malignancies.

Large hepatitis delta antigen modulates transforming growth factor-beta signaling cascades: implication of hepatitis delta virus-induced liver fibrosis

BACKGROUND & AIMS

Transforming growth factor-beta (TGF-beta) has been implicated in the pathogenesis of liver disease. TGF-beta is involved in liver regeneration and in the fibrotic and cirrhotic transformation with hepatitis viral infection. Hepatitis delta virus (HDV) infection causes fulminant hepatitis and liver cirrhosis. To elucidate the molecular mechanism of HDV pathogenesis, we examined the effects of HDV-encoded-only protein, the small hepatitis delta antigen (SHDAg), and the large hepatitis delta antigen (LHDAg), on TGF-beta- and c-Jun-induced signaling cascades.

METHODS

The effects of either SHDAg or LHDAg on TGF-beta- and c-Jun-induced signaling cascades in Huh7 and Cos7 cells were investigated by luciferase reporter gene assay, immunoprecipitation assay, electrophoretic mobility shift assay, Western blot analysis, and confocal microscopy analysis.

RESULTS

The LHDAg, but not the SHDAg, potentiated TGF-beta- and c-Jun-induced signal activation, and the isoprenylation of LHDAg played a major role in signaling cascades. LHDAg synergistically activated hepatitis B virus X protein-mediated TGF-beta and AP-1 signaling cascades. In addition, LHDAg enhanced the protein expression level of TGF-beta-induced plasminogen activator inhibitor-1.

CONCLUSIONS

LHDAg may induce liver fibrosis through the regulation of TGF-beta-induced signal transductions. This regulation of TGF-beta-mediated signaling is accomplished by the isoprenylation of LHDAg, which is a novel mechanism involved in HDV pathogenesis.

Large hepatitis delta antigen modulates transforming growth factor-beta signaling cascades: implication of hepatitis delta virus-induced liver fibrosis

BACKGROUND & AIMS

Transforming growth factor-beta (TGF-beta) has been implicated in the pathogenesis of liver disease. TGF-beta is involved in liver regeneration and in the fibrotic and cirrhotic transformation with hepatitis viral infection. Hepatitis delta virus (HDV) infection causes fulminant hepatitis and liver cirrhosis. To elucidate the molecular mechanism of HDV pathogenesis, we examined the effects of HDV-encoded-only protein, the small hepatitis delta antigen (SHDAg), and the large hepatitis delta antigen (LHDAg), on TGF-beta- and c-Jun-induced signaling cascades.

METHODS

The effects of either SHDAg or LHDAg on TGF-beta- and c-Jun-induced signaling cascades in Huh7 and Cos7 cells were investigated by luciferase reporter gene assay, immunoprecipitation assay, electrophoretic mobility shift assay, Western blot analysis, and confocal microscopy analysis.

RESULTS

The LHDAg, but not the SHDAg, potentiated TGF-beta- and c-Jun-induced signal activation, and the isoprenylation of LHDAg played a major role in signaling cascades. LHDAg synergistically activated hepatitis B virus X protein-mediated TGF-beta and AP-1 signaling cascades. In addition, LHDAg enhanced the protein expression level of TGF-beta-induced plasminogen activator inhibitor-1.

CONCLUSIONS

LHDAg may induce liver fibrosis through the regulation of TGF-beta-induced signal transductions. This regulation of TGF-beta-mediated signaling is accomplished by the isoprenylation of LHDAg, which is a novel mechanism involved in HDV pathogenesis.

Modulation of the transforming growth factor-beta signal transduction pathway by hepatitis C virus nonstructural 5A protein

Transforming growth factor-beta (TGF-beta) is implicated in the pathogenesis of liver disease. TGF-beta is involved both in liver regeneration and in the fibrotic and cirrhotic transformation with hepatitis viral infection. Hepatitis C virus (HCV) infection often leads to cirrhosis and hepatocellular carcinoma. HCV nonstructural 5A (NS5A) protein is a multifunctional protein that modulates cytokine-mediated signal transduction pathways. To elucidate the molecular mechanism of HCV pathogenesis, we examined the effect of NS5A protein on TGF-beta-stimulated signaling cascades. We show that NS5A protein inhibited the TGF-beta-mediated signaling pathway in hepatoma cell lines as determined by reporter gene assay. To further investigate the role of NS5A, we examined the protein/protein interaction between NS5A and TGF-beta signal transducers. Both in vitro and in vivo binding data showed that NS5A protein directly interacted with TGF-beta receptor I (TbetaR-I) in hepatoma cell lines. This interaction was mapped to amino acids 148-238 of NS5A. We also found that NS5A protein co-localized with TbetaR-I in the cytoplasm of Huh7 cells and inhibited TGF-beta-mediated nuclear translocation of Smad2. Furthermore, we demonstrate that NS5A protein abrogated the phosphorylation of Smad2 and the heterodimerization of Smad3 and Smad4. To further explore the relevance to viral infection, we examined the effect of the HCV subgenomic replicon on the TGF-beta signaling pathway. We show that the HCV subgenomic replicon also inhibited TGF-beta-induced signaling cascades. These results indicate that HCV NS5A modulates TGF-beta signaling through interaction with TbetaR-I and that NS5A may be an important risk factor in HCV-associated liver pathogenesis.

Intestinal transformation results in transforming growth factor-beta-dependent alteration in tumor cell-cell matrix interactions

BACKGROUND

An alteration in the expression of and response to transforming growth factor-beta 1 (TGF-beta 1) appears to be an important event during colorectal carcinogenesis. However, the precise role of TGF-beta 1 in colorectal carcinogenesis is not clear. We have previously described in detail the changes in cell proliferation and differentiation caused by chronic exposure to TGF-beta 1. In this study we sought to better characterize the changes in tumor cell-cell matrix interactions seen during TGF-beta 1-mediated intestinal transformation.

METHODS

Rat intestinal epithelial cells (RIE) and RIE cells transformed by chronic exposure to TGF-beta 1 (RIE-Tr) were treated with TGF-beta 1 and production of components of the plasmin/plasminogen system measured by ELISA and Western blotting. TGF-beta 1 effects on invasion and adhesion were determined in vitro. The role of urokinase on TGF-beta 1-mediated invasion and adhesion were determined using immunoneutralization. The role of COX-2 was determined using a specific COS-2 inhibitor.

RESULTS

TGF-beta 1 had no effect on RIE-1 adhesion to collagen types I and IV, fibronectin, and laminin, or invasion through collagen types I and IV. However, 5 ng/mL TGF-beta 1 significantly increased the invasiveness and decreased the adhesiveness of RIE-Tr. This effect of TGF-beta 1 on RIE-Tr was associated with a significant increase in plasmin activity secondary to increased expression of uPA. TGF-beta 1 had no effect on either uPA receptor or PAI-1 in this system. Antibodies to uPA completely blocked the TGF-beta 1-mediated invasiveness of the RIE-Tr cells and returned their adhesiveness to basement membrane proteins to baseline. Addition of the selective Cox-2 inhibitor SC-58125 resulted in a dose-dependent decrease in TGF-beta 1-mediated invasion and uPA expression.

CONCLUSION

This study provides additional evidence for TGF-beta 1 as a tumor promoter during intestinal carcinogenesis and a possible new mechanism for Cox-2-related colon carcinogenesis.

Towards defining roles and relationships for tenascin-C and TGFbeta-1 in the normal and neoplastic urinary bladder

Tenascin-C (TN-C) is an extracellular matrix glycoprotein expressed along epithelial/stromal boundaries during tissue remodelling events, such as those that occur during morphogenesis, wound healing, and tumour invasion. Using clinical specimens and a range of in vitro models that simulate homeostasis, wound healing, and malignant progression, this study sought to establish the patterns of TN-C expression in normal and neoplastic bladder and to determine the role of exogenous transforming growth factor beta-1 (TGFbeta-1), interleukin-4 (IL-4), basic fibroblast growth factor (bFGF), tumour necrosis factor alpha (TNFalpha), and interferon gamma (IFNgamma) in the induction of TN-C expression by bladder uro-epithelial cells. The findings indicate that normal urothelial cells may express TN-C, with both TGFbeta-1 and IL-4 able to induce expression. TN-C was not expressed in neoplastic urothelium, although both TN-C and TGFbeta-1 may be involved in tissue remodelling during papillary tumour formation and invasion. Furthermore, the urothelium of high-grade papillary tumours and carcinoma in situ specimens exhibited little TGFbeta-1 immunoreactivity, compared with the urothelium of low-grade tumours and normal specimens, suggesting an association between TGFbeta-1 expression and urothelial differentiation. A tumour invasion model, in which established bladder cancer cell lines were seeded onto a normal bladder stroma, corroborated the evidence from the clinical specimens and demonstrated that TN-C was strongly expressed around foci of stromal invasion. Thus, TN-C immunoreactivity may provide an additional tool in the assessment of early stromal invasion in bladder cancer.

Role of TGFbeta signaling in skin carcinogenesis

The TGFbeta signaling pathway is one of the most important mechanisms in the maintenance of epithelial homeostasis. Alterations leading to either the repression or enhancement of this pathway have been shown to affect cancer development. Although TGFbeta inhibits growth of normal epithelial cells, it is paradoxically overexpressed in many epithelial cancers. It has been postulated that TGFbeta acts as a tumor suppressor at the early stages of carcinogenesis, but overexpression of TGFbeta at late stages of carcinogenesis may be a critical factor for tumor invasion and metastasis. The detailed mechanisms regulating this functional switch of TGFbeta remain to be elucidated. The relevance of the TGFbeta signaling pathway to the development of primary epithelial tumors in man has been further substantiated by the discovery of mutations in TGFbeta receptors and in the downstream signaling mediators, the Smads. The epidermis is one of the major targeting tissues for TGFbeta signaling. Chemical carcinogenesis studies have revealed a paradoxical effect of TGFbeta on skin carcinogenesis: inhibition of papilloma formation but promotion of malignant conversion. In addition, deletion of the TGFbeta type II receptor accelerates skin carcinogenesis. This review focuses on our current understanding of the role of TGFbeta signaling in skin carcinogenesis.

The physical parameters and molecular events associated with radiation-induced lung toxicity

Radiation therapy (RT) is frequently used to treat patients with tumors in and around the thorax. Clinical radiation pneumonitis is a common side effect, occurring in 5% to 20% of patients. Efforts to identify patients at risk for pneumonitis have focused on physical factors, such as dose and volume. Recently, the underlying molecular biological mechanisms behind RT-induced lung injury have come under study. Improved knowledge of the molecular events associated with RT-induced lung injury may translate into a better ability to individualized therapy. This review discusses our current understanding of the physical and molecular factors contributing to RT-induced pulmonary injury.

Rhodostomin inhibits the transforming growth factor-beta1-enhanced adhesion activity of ROS 17/2.8 osteosarcoma cells

We have investigated the effect of transforming growth factor-beta1 (TGF-beta1) on the in vitro adhesion activity of the rat osteosarcoma cell lines (ROS 17/2.8) to extracellular matrix substrata, including fibronectin, type I and IV collagen, as well as laminin. The interaction of Arg-Gly-Asp (RGD) and rhodostomin, an RGD containing snake venom, with TGF-beta1 on the cell adhesion was also evaluated. The results showed that incubation with various concentration of TGF-beta1 (1-15 ng/ml) significantly increased the adhesion activity (1.4 to 2.5 folds) of ROS 17/2.8 to fibronectin and type I collagen (p<0.01), whereas the adhesion activity to laminin and type IV collagen was slightly elevated (1.1 to 1.5 folds). The peak effect of TGF-beta1 on the cell adhesion occurred after pretreatment of ROS 17/2.8 with TGF-beta1 for 6 hours. Treatment with Arg-Gly-Asp-Ser (RGDS) and rhodostomin effectively suppressed the TGF-beta1-enhanced adhesion activity to fibronectin and type I collagen. This study demonstrated that the up-regulated cell adhesion activity of ROS 17/2.8 cells by the TGF-beta1 can be inhibited by the rhodostomin.

Opposing actions of two transforming growth factor-beta isoforms on pituitary lactotropic cell proliferation

Three transforming growth factor-beta protein isoforms (TGFbeta1, TGFbeta2, and TGFbeta3) have been identified in mammals. These isoforms appear to have similar actions on cell growth in various tissues. In rat pituitary tissue, TGFbeta1 is localized in PRL-secreting lactotropes and has been shown to act on lactotropes to inhibit estradiol-induced cell proliferation. The steroid inhibits the production and secretion of TGFbeta1. It is not known whether the other two isoforms are produced in and/or act on lactotropes. Using immunocytochemical detection techniques, we determined that, like TGFbeta1, TGFbeta3 is colocalized with PRL in the anterior pituitary of Fischer-344 female rats. Administration of estradiol increased TGFbeta3-immunoreactive cell numbers, TGFbeta3 protein, and TGFbeta3 messenger RNA levels in the pituitary. Determinations of TGFbeta3 actions in vitro in primary cultures of pituitary cells indicated that TGFbeta3 concentration dependently increases lactotropic cell proliferation. The growth-promoting action of TGFbeta3 was potentiated by estradiol. Immunoneutralization studies indicated that although TGFbeta1 antibody failed to prevent estradiol's mitogenic action, it potentiated the mitogenic action of TGFbeta3. In contrast, TGFbeta3-neutralizing antibody inhibited lactotropic cell proliferation by estradiol. These data indicate that unlike many other tissues, TGFbeta1 and TGFbeta3 have opposite actions on lactotropic proliferation in the pituitary. Furthermore, TGFbeta1 and TGFbeta3 may be involved in estradiol's mitogenic action on lactotropes.

Transforming growth factor-beta1 stimulates contraction of human glioblastoma cell-mediated collagen lattice through enhanced alpha2 integrin expression

Rapid invasiveness is a feature of the highly malignant glioblastoma tumor and is closely related to patient prognosis. The interaction between extracellular matrix (ECM) and cell surface receptors such as integrin heterodimers play a key role in the process of tumor invasion. We investigated the effects of transforming growth factor-beta1 (TGF-beta1), which is a mitogenic factor for glial cells, on integrin expression in T98G human glioblastoma cells using an in vitro model 3-dimensional collagen lattice. Exogenously applied TGF-beta1 dose-dependently enhanced collagen lattice contraction. Among the inhibitory antibodies tested against alpha integrin subunits, the anti-alpha2 antibody, P1-E6, alone prevented the enhanced contractile response by TGF-beta1, whereas any alpha integrin antibody (including P1-E6) had little effect on lattice contraction when cultured without TGF-beta1. RT-PCR analysis revealed that TGF-beta1 strongly increased alpha2 integrin transcript level. Furthermore, pretreatment with antisense phosphorothioate oligodeoxynucleotides against human alpha2 integrin using hemagglutinating virus of Japan (HVJ) liposome-mediated transfer prevented the effects of TGF-beta1 and also reduced the lattice contraction even in the absence of TGF-beta1. This data indicates that increased expression of alpha2 integrin is responsive to enhanced collagen lattice contraction by TGF-beta1. We suggest that TGF-beta1 exerts its effects on the invasive property of glioblastoma cells via upregulation of the alpha2 integrin subunit expression.

Cyclooxygenase-2 alters transforming growth factor-beta 1 response during intestinal tumorigenesis

BACKGROUND

Recent investigation suggests that cyclooxygenase-2 plays an important role in colorectal carcinogenesis. Transforming growth factor-beta1 (TGF-beta 1) is one of the most potent stimulators of cyclooxygenase-2 expression. A key step in intestinal tumorigenesis involves alteration of the normal cellular response to TGF-beta 1. We have hypothesized that overexpression of cyclooxygenase-2 alters intestinal epithelial response to TGF-beta 1.

METHODS

RIE-1 cells were stably transfected with rat cyclooxygenase-2 complementary DNA in either the sense (RIE-S) or antisense (RIE-AS) orientation. Tumor cell invasion was assessed with a modified Boyden collagen type I invasion assay in the presence of TGF-beta 1, antibody to urokinase plasminogen activator (uPA), or the selective cyclooxygenase-2 inhibitor SC-58125. Expression of uPA, uPA receptor, and plasminogen activator inhibitor-1 were determined by Western blot and enzyme-linked immunosorbent assay.

RESULTS

RIE-1 and RIE-AS did not invade although RIE-S cells were minimally invasive at baseline. TGF-beta 1 had no effect on RIE-1 or RIE-AS invasion; however, TGF-beta 1 significantly upregulated RIE-S cell invasion. All 3 RIE cell lines produce minimal uPA under basal conditions. TGF-beta 1 upregulated uPA production only in the RIE-S cells. Both antibody to uPA and SC-58125 reversed TGF-beta-mediated RIE-S cell invasion. SC-58125 inhibited TGF-beta-mediated RIE-S uPA production.

CONCLUSIONS

These results demonstrate that overexpression of cyclooxygenase-2 alters intestinal epithelial response to TGF-beta 1, which may be a mechanism by which cyclooxygenase-2 promotes colon carcinogenesis.

Blockade of tumor cell transforming growth factor-betas enhances cell cycle progression and sensitizes human breast carcinoma cells to cytotoxic chemotherapy

We have examined the effect of neutralizing TGF-beta antibodies on cisplatin-mediated cytotoxicity against MDA-231 human breast tumor cell spheroids. These tridimensional in vitro systems have been shown to recapitulate the drug sensitivity pattern of tumor cells in vivo. MDA-231 tumor cell spheroids exhibit higher protein levels of the cyclin-dependent kinase (Cdk) inhibitors p21 and p27 and >10-fold lower Cdk2 activity compared to adherent cell monolayers, as well as pRb hypophosphorylation, a predominant G1 population, and a cisplatin 1-h IC50 of approximately 100 microM. Treatment of MDA-231 cells in monolayer with cisplatin for 1 h, subsequently grown as spheroids, increased steady-state TGF-beta1 mRNA levels, secretion of active TGF-beta, cellular Cdk2 activity, pRb phosphorylation, and p21 protein levels, while downregulating p27. Accumulation of cells in G2M and progression into S were noted 48 h after treatment with 100 microM cisplatin. We tested whether drug-induced upregulation of TGF-beta1 and p21, perhaps by preventing cell cycle progression, were protective mechanisms against drug-mediated toxicity by using neutralizing anti-TGF-beta antibodies. Anti-TGF-beta antibodies diminished the induction of p21, enhanced the activation of Cdk2, and facilitated progression into S and G2M following cisplatin treatment. This resulted in a >twofold enhancement of drug-induced DNA fragmentation and a shift in the cisplatin 1-h IC50 from 100 to <10 microM. These data suggest that tumor cell TGF-beta1 may protect from DNA damage and that postchemotherapy administration of TGF-beta inhibitors may facilitate progression beyond G1/S, potentially increasing the efficacy of cytotoxic chemotherapy.

Systemic transforming growth factor-beta in patients with bone marrow fibrosis--pathophysiological implications

Idiopathic myelofibrosis (IMF) and secondary myelofibrosis (MF) are characterized by bone marrow (BM) fibrosis, neoangiogenesis, and increased extracellular matrix (ECM) proteins. These characteristics may be partially attributed to transforming growth factor beta (TGF-beta), a cytokine produced by monocytes. In myelofibrosis, monocytes are increased and activated with concomitant up-regulation of intracytoplasmic TGF-beta. We have therefore determined systemic TGF-beta in patients with either BM fibrosis: IMF, n = 18; MF, n = 16; or without BM fibrosis: hematologic disorders with normal platelets (n = 31); high platelets (n = 9); or normal controls (n = 27). Compared with nonfibrosis sera, there was significant TGF-beta elevation in BM fibrosis sera (P < 0.0001). Most (>80%) of the TGF-beta is active and belongs to the-beta1 isoform. In situ hybridization and immunohistochemical analyses in BM biopsy sections showed a marked increase in TGF-beta1 only in patients with fibrosis. Moreover, TGF-beta protein was detected mainly in myelomonocytic-like predominant areas. To determine if another functionally similar cytokine, basic fibroblast growth factor (bFGF), may be important to BM fibrosis, we quantitated sera levels and found elevation in 57% compared with 100% elevation for TGF-beta. The data indicate that irrespective of etiology, systemic TGF-beta is elevated in patients with BM fibrosis. TGF-beta likely plays an important role in the development of BM fibrosis. The study also provides a significant parameter for early therapeutic intervention in BM fibrosis.

Transforming growth factor-beta 1 inhibits generation of angiostatin by human pancreatic cancer cells

BACKGROUND

Angiostatin, a proteolytic fragment of plasminogen, is a potent inhibitor of angiogenesis. We have previously shown that the human pancreatic cancer cell line ASPC-1 produces enzymatic activity capable of generating angiostatin. In this study we sought to determine whether angiostatin production by ASPC-1 cells was regulated by the growth factor transforming growth factor-beta 1 (TGF-beta 1), a key mediator of tumor angiogenesis.

METHODS

ASPC-1 cells were grown to 70% to 80% confluence in 20% fetal calf serum-RPMI. Medium was changed to serum free. TGF-beta 1 was added at concentrations of 0, 1, 5, and 10 ng/mL with or without plasminogen activator inhibitor type-1 (PAI-1) at concentrations of 0, 5, 10, 50, and 100 micrograms/mL. Cells were then cultured for an additional 24 hours. The serum-free conditioned medium was obtained. Angiostatin generation was determined by incubating 20 micrograms of plasminogen with 100 microL of serum-free conditioned medium for 0, 1, 2, 3, 6, 12, and 24 hours. Samples were run on 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred. The membrane was probed with a monoclonal antibody to the kringle 1-3 fragment of plasminogen and developed using enhanced chemiluminescence.

RESULTS

TGF-beta 1 and PAI-1 inhibited the conversion of plasminogen into angiostatin in a time- and dose-dependent manner. Antibody to PAI-1 completely blocks TGF-beta 1 mediated angiostatin inhibition.

CONCLUSIONS

TGF-beta 1 inhibits the generation of the antiangiogenic molecule angiostatin by human pancreatic cancer cells in a time- and dose-dependent manner. This effect is mediated through modulation of the plasminogen/plasmin system.

The relevance of transforming growth factor beta 1 in pulmonary injury after radiation therapy

The maximum dose of radiation which can be delivered to a tumor is limited by the tolerance of the surrounding normal tissues. The ability to identify patients at high or low risk of injury from radiation therapy might enable the clinician to tailor radiation doses in order to maximize efficacy and minimize risk. The cytokine transforming growth factor beta 1 (TGF beta 1) has been implicated in the development of normal tissue injury after irradiation in several organs, including the lung. Herein, the evidence supporting the role of TGF beta 1 in radiation-induced lung injury is reviewed. Using the treatment of non-small cell lung cancer as a model, we also discuss how it may be possible to identify patients at risk for this complication using measurements of plasma TGF beta 1, and how this information may be used in the future to adjust doses of radiation in the treatment of lung cancer.

Relation between histological intensity of transforming growth factor-beta isoforms in human osteosarcoma and the rate of lung metastasis

Even though adjuvant chemotherapy has improved the 5-year survival rate of osteosarcoma patients, a significant percentage of patients eventually die from lung metastasis. Since transforming growth faCtor-beta (TGF-beta) has been demonstrated to be related to the tumor progression, we investigated the clinical implications of the presence of TGF-beta isoforms in 16 human osteosarcoma tissue. There were 10 males and 6 females with a mean age of 20.8 years of age (range, 8 to 57 years). Biopsied specimen before chemotherapy was fixed in 10% formalin, demineralized and followed by paraffin embedding. The locations of tumor included femur (10), tibia (3), humerus (1), fibula (1), and ilium (1). Histologic subtypes included osteoblastic (11), chondroblastic (2), and fibroblastic (3). All patients were followed for a minimum of 1 year (range 12 to 44 months) or to the development of lung metastasis. Five patients (31.3%) developed subsequent lung metastasis during the follow up. We used immunohistochemistry technique to investigate the presence of the TGF-beta isoforms in osteosarcoma tissue and its relationship to the subsequent pulmonary metastasis. The results showed the presence of one or more TGF-beta isoforms in tumor cells in osteosarcoma tissues (13 of 16, 81.3%) in all of the subtypes. However, minimal presence of TGF-beta isoforms was shown in the tumor bone matrix. The expression of TGF-beta1 or TGF-beta3 isoforms was associated with a higher rate of subsequent lung metastasis (p < 0.05, chi-square test). Further research is warranted to determine the utility of routine TGF-beta analysis in the clinical practice.

Oxidative damage and transforming growth factor beta 1 expression in pretumoral and tumoral lesions of human intestine

The aim of this study was to evaluate a possible relationship between oxidative stress and transforming growth factor beta 1 (TGF beta 1) expression in human colon adenocarcinoma. Crohn's disease, an inflammatory pathology of the intestine often regarded to as precancerous, was also examined. Indices of impaired redox balance were monitored in blood and in bioptic samples from 10 adult patients with adenocarcinoma of the colon and from five patients with Crohn's disease. On tissue samples TGF beta 1 mRNA expression was also determined. Ten healthy adults provided normal reference values for plasma indices of oxidative stress, and normal tissue distant from the lesions was used for comparative analysis. Fluorescent adducts with plasma proteins of malonaldehyde (MDA) and 4-hydroxynonenal (HNE) were significantly lower than controls in the plasma from cancer patients and significantly higher in the plasma from Crohn's patients. In adenocarcinoma biopsies, susceptibility to lipid peroxidation processes and TGF beta 1 expression were below the relative control; in Crohn's disease, lipid peroxidation and cytokine expression were both above the relative control. The findings obtained suggest the existence of an association between oxidative damage and fibrogenic cytokine expression in the human intestine. Further studies are needed to conclusively prove the correlation between the two events.

Structure of the insect head in ontogeny and phylogeny: a view from Drosophila

Evolutionary, developmental and insect biologists are currently using a three-pronged approach to study the evolution and development of the insect head. First, genetic manipulation of the fruit fly Drosophila melanogaster has led to the identification of many genes, including the segmentation and homeotic genes, that are important for embryonic pattern formation and development. Second, a comparison of orthologous gene expression patterns in other insects reveals that these regulatory genes are deployed in similar, yet distinct, patterns in different insects. Third, comparisons of embryonic morphology with gene expression patterns suggest that in general these genes promote a common insect body plan, but that variations in gene expression can often be correlated to variations in morphology. Here, we present a detailed review of the development of the cephalic ectoderm of Drosophila and extrapolate to development of a generalized insect head. Our analysis of the variations among insect species, in both morphology and gene expression patterns, conducted within an evolutionary framework supported by traditional phylogenies and paleontology provides the basis for hypotheses about the genetic factors governing morphologic and developmental evolution.

Transforming growth factor beta as a clinical biomarker for prostate cancer

OBJECTIVES

Tumor biomarkers to detect prostate cancer earlier may reduce prostate cancer deaths. Transforming growth factor-beta1 and -beta2 (TGF-beta1 and -beta2) become overexpressed in prostate cancer and might be useful tumor markers of prostate cancer.

METHODS

Plasma and urinary TGF-beta1 and plasma TGF-beta2 levels were studied preoperatively in 74 consecutive patients who had prostate cancer and underwent radical prostatectomy and were compared with those of 29 similarly aged male control patients who had no clinical evidence of prostate cancer.

RESULTS

Plasma TGF-beta1 levels were similar in both prostate cancer and control groups and did not correlate with serum prostate-specific antigen (PSA), clinical and pathologic stages, or Gleason grade. Urinary TGF-beta1 levels, however, increased 3.5-fold in patients with prostate cancer relative to controls and tended to be higher with advancing clinical and pathologic stages. Plasma TGF-beta2 levels, like plasma TGF-beta1 levels, were similar for both the study and control groups, but when stratified by pathologic stage or Gleason grade, patients with prostate cancer with pathologic Stage T2a and Gleason grade of 3 or less had significantly increased plasma TGF-beta2 levels as compared with either control patients or patients with prostate cancer with pathologic Stages T2b/T2c and T3/T4 or Gleason grade of 4 or more, suggesting that early prostate cancer may contribute to plasma TGF-beta2 levels.

CONCLUSIONS

Unlike plasma TGF-beta1 levels, urinary TGF-beta1 and plasma TGF-beta2 levels were higher in patients with prostate cancer and may be useful biomarkers of prostate cancer.

Plasma transforming growth factor-beta 1 reflects disease status in patients with lung cancer after radiotherapy: a possible tumor marker

PURPOSE

To determine the frequency with which elevated plasma transforming growth factor-beta 1 (TGF beta 1) concentrations occur in lung cancer patients, to determine the kinetics of TGF beta 1 expression during and after radiotherapy and to correlate plasma TGF beta 1 levels with disease status after treatment.

MATERIALS AND METHODS

Plasma samples were obtained before, during and after radiotherapy in 54 patients with lung cancer and 20 normal controls. Plasma TGF beta 1 levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

Baseline TGF beta 1 levels in lung cancer patients and normal controls were 13.0 +/- 2.5 and 4.4 +/- 0.3 ng/ml, respectively. Elevated TGF beta 1 were found in 50% (27/54) of lung cancer patients. During radiation therapy plasma TGF beta 1 levels declined, however, by the completion of treatment the mean TGF beta 1 level had not normalized in patients with lung cancer. The TGF beta 1 level at last follow-up correlated with disease status in those patients with an increased pretreatment plasma level. Three of four patients with no evidence of cancer had normal follow-up TGF beta 1 levels, compared to 2/16 patients with residual or recurrent tumor (P = 0.02).

CONCLUSIONS

Elevated plasma TGF beta 1 levels occur frequently in patients with lung cancer. In those patients with an elevated plasma TGF beta 1 level at diagnosis, monitoring this level may be useful in detecting both disease persistence and recurrence after therapy.

Phorbol ester (12-O-tetradecanoylphorbol 13-acetate) prevents ornithine decarboxylase inhibition and apoptosis and L1210 leukemic cells exposed to TGF-beta 1

Previous studies have shown that growth suppression and apoptosis of leukemic cells exposed to TGF-beta 1 is associated with the inhibition of ornithine decarboxylase (ODC)--the key enzyme of polyamine pathway. The aim of the present study was to evaluate the influence of 12-O-tetradecanoylphorbol 13-acetate (TPA)--a potent ODC inducer on antiproliferative and apoptotic effects of TGF-beta 1 in L1210 leukemic cells. Cells were incubated in 2% FCS/RPMI-1640 medium, supplemented with TGF-beta 1 (2 ng/ml). TPA (100 ng/ml) or alpha-difluoromethylornithine (DFMO) (5 mM). Cell proliferation, apoptosis and necrosis were evaluated using [methyl-3H] thymidine, electron microscopy, electrophoresis of DNA and trypan blue exclusion. Expression and activity of ODC were determined by RT-PCR and measurement of 14CO2 release from L-1-14C ornithine, respectively. TGF-beta 1 inhibited proliferation and induced apoptotic and necrotic cell death in L1210 leukemic cells. The above effects were associated with the inhibition of ODC expression and activity, measured 2 and 4 hr after TGF-beta 1 administration, respectively. The presence of DFMO, an irreversible inhibitor of ODC, led to apoptotic fragmentation of DNA, similar to that observed in TGF-beta 1-treated cultures. Administration of TPA simultaneously with TGF-beta 1 significantly reduced antiproliferative, apoptotic and necrotic effects of TGF-beta 1, and prevented its inhibitory action of ODC expression and activity. It is concluded that: down-regulation of ODC expression may be one of the early events associated with TGF-beta 1-evoked suppression of growth and apoptosis; ODC is involved in the mechanism of protective action of TPA on TGF-beta 1-related growth inhibition of L1210 leukemic cells.

TGF beta-induced growth inhibition in primary fibroblasts requires the retinoblastoma protein

Transforming growth factor beta (TGF beta) inhibits cell proliferation by inducing a G1 cell-cycle arrest. Cyclin/CDK complexes have been implicated in this arrest, because TGF beta treatment leads to inhibition of cyclin/CDK activity. We have investigated the role of the retinoblastoma protein (pRb) in TGF beta-induced growth arrest by using RB+/+ and RB-/- primary mouse embryo fibroblasts. In both of these cell types, TGF beta inhibits CDK4-associated kinase activity. However, whereas CDK2-associated kinase activity was completely inhibited by TGF beta in the wild-type cells, it was reduced only slightly in the RB mutant cells. In addition, at high-cell density the growth-inhibitory effects of TGF beta are no longer observed in the RB-/- cells; on the contrary, TGF beta treatment promotes the growth of these mutant fibroblasts. Thus, under certain cellular growth conditions, elimination of pRb transforms the growth-inhibitory effects of TGF beta into growth-stimulatory effects. These observations could help to explain why TGF beta is often found to enhance tumorigenicity in vivo and why inactivation of the RB gene leads to tumorigenesis.

Cytokines in tumour growth, migration and metastasis

A wide variety of cytokines are involved at every stage of tumour growth and dissemination. Primary tumour growth is helped by growth factors and angiogenic factors. These may either be produced by tumour cells themselves or be provided by one of the infiltrating cell populations, such as vascular endothelium or leukocytes. The influx of these cells is, in turn, under the control of the chemokines, a chemoattractant subfamily of cytokines. Autocrine motility factors, in conjunction with cytokines that regulate the production and activity of proteases capable of breaking down components of the extracellular matrix, are involved in the dispersal of cells from primary tumours, leading to the formation of metastases. The development of metastases may also be under the control of circulating cytokines released from the primary tumour. The ways in which cytokines and allied growth factors regulate tumour growth and development are both complex and controversial. However, the study of this system will provide a more profound understanding of tumour biology and may lead the way for the development of novel therapeutic approaches.

Stage-specific gene expression during hepatocarcinogenesis in the rat

The alteration of genetic expression ubiquitously seen in both preneoplastic and neoplastic tissues has been investigated for many years in the hope that the critical molecular changes resulting in cancer can be elucidated. The alteration of the expression of specific genes has already been employed in diagnostic and even screening procedures for this disease. In the past many observations of such alterations have led to a variety of theories but not definitive generalizations. Studies of the alteration of genetic expression may now be viewed in the light of our understanding of the multistage nature of neoplastic development. This brief review describes a number of genes the expressions of which are altered during the stages of initiation and promotion, in contrast to the alteration of expression of genes during the stage of progression. The promotion stage is concerned primarily with the chronic interaction of promoting agents in the environment with the genetic apparatus of the cell, played out on the altered genetic background resulting from the stage of initiation. In contrast, the progression stage is characterized primarily by an evolving karyotypic instability resulting in continual genetic changes during this stage. On the basis of these distinctions it is possible to identify genes the altered expression of which is unique to the stage of progression. The identification of these genes and an understanding of mechanisms resulting in their altered expression will allow not only a better molecular characterization of the progression stage but also the quantitative analysis of neoplastic development in several model animal systems as well as eventually in the human.

Transforming growth factor-beta in GI neoplasia, wound healing and immune response

The last decade has been marked by tremendous advances in the biochemical and functional characterization of TGF-betas and their receptors in normal and transformed cells. TGF-betas have been shown to modulate proliferation, differentiation and motility of different cell types in a number of in vitro model systems and in some cases with some intriguing results. It is obvious that there is no simple pattern that explains the TGF-betas biological activity in vitro and their effects on cell behaviour need to be assessed in the context of an appropriate physiological cellular environment. Cell-cell and cell-matrix interactions, the differentiating status of the cell together with the functional activity of other soluble growth factors can influence how TGF-betas modulate cell behaviour. However, the overwhelming interest in this field shown by clinicians and basic scientists is rapidly increasing our understanding of how growth factors such as TGF-betas regulate the homeostasis of the GI mucosa and their role in gastrointestinal carcinogenesis.

Anti-(transforming growth factor beta) antibodies with predefined specificity inhibit metastasis of highly tumorigenic human xenotransplants in nu/nu mice

Monoclonal antibodies (mAb) were prepared against conjugated transforming growth factor beta 1 (TGF beta 1) peptides: amino acid positions 48-60 and positions 86-101. Two antibodies, mAb 16-3G1 [anti-(48-60)] and mAb 5-2G6 [anti-(86-101)] cross-reacted with native TGF beta 1, -beta 2 and -beta 3 (16-3G1) or only with native TGF beta 1 (5-2G6). Both mAb were used to characterize TGF beta-mediated effects on the metastatic potential in nude mice of human carcinoma cell line SLU-1 and its metastatic subline SLU-M1. Autocrine TGF beta 1-mediated up-regulation of cell proliferation and its suppression by anti-TGF beta antibodies in vitro was recorded for SLU-M1 cells whereas SLU-1 cell proliferation in vitro appeared to be refractory to anti-TGF beta antibodies and exogenous TGF-beta 1. However, the potential of s.c. tumours to develop distant metastases in nude mice was about the same for both cell lines. Development of primary tumours and distant metastases could be suppressed by treatment of mice with anti-TGF beta antibodies. Thus we assume that the metastatic potential of tumour cells is independent of TGF beta-mediated growth-regulation effects in vitro. The anti-TGF beta-induced suppression of tumour progression and metastasis in nude mice might rather result from stimulation of the immune surveillance. TGF beta-mediated autocrine down-regulation of MHC-unrestricted cytotoxicity of activated human monocytes and CD56+ LAK cells and its reversion by anti-TGF beta antibodies could be readily demonstrated. In all our experimental series, the neutralizing potential of both anti-TGF beta antibodies, though directed against opposite sites of the TGF beta 1 molecule, was very similar.