TGFBI deficiency predisposes mice to spontaneous tumor development

Identification and validation of TGFBI as a promising prognosis marker of clear cell renal cell carcinoma

OBJECTIVE

To identify prognostic biomarkers in clear cell renal cell carcinoma (ccRCC) using a proteomic approach.

MATERIAL AND METHODS

We performed a comparative proteomic profiling of ccRCC and normal renal tissues from 9 different human specimens. We assessed differential protein expression by iTRAQ (isobaric tagging reagent for absolute quantify) labeling with regard to tumor aggressiveness according to the stage, size, grade, and necrosis (SSIGN) score and confirmed our results using Western blot (9 patients) and immunohistochemistry (135 patients) analysis.

RESULTS

After proteomic analysis, 928 constitutive proteins were identified. Among these proteins, 346 had a modified expression in tumor compared with that of normal tissue. Pathway and integrated analyses indicated the presence of an up-regulation of the pentose phosphate pathway in aggressive tumors. In total, 14 proteins were excreted and could potentially become biomarkers. Overexpression of transforming growth factor, beta-induced (TGFBI) in ccRCC was confirmed using Western blot and immunohistochemistry analysis. A significant association was found between the presence of TGFBI expression with tumor category T3-4 (P<0.0001), Fuhrman grades III and IV (P<0.0001), tumor size>4cm (P<0.0001), presence of tumor necrosis (P<0.0001), nodal involvement (n = 0.009), metastasis (P = 0.012), SSIGN score≥5 (P<0.0001), cancer progression (P<0.0001), and cancer-specific death (P<0.0001). Cancer-specific survival was significantly better for patients with no cytoplasmic TGFBI expression (1-, 3-, 5-y cancer-specific survival of 94.7%, 87.8%, and 73.4% vs. 92.9%, 71.2%, and 49.8%, respectively; P<0.0001).

CONCLUSION

We identified 346 proteins involved in renal carcinogenesis and confirmed the presence of a metabolic shift in aggressive tumors. TGFBI was overexpressed in tumors with high SSIGN scores and was significantly associated with oncologic outcomes.

Paracrine interactions between LNCaP prostate cancer cells and bioengineered bone in 3D in vitro culture reflect molecular changes during bone metastasis

As microenvironmental factors such as three-dimensionality and cell-matrix interactions are increasingly being acknowledged by cancer biologists, more complex 3D in vitro models are being developed to study tumorigenesis and cancer progression. To better understand the pathophysiology of bone metastasis, we have established and validated a 3D indirect co-culture model to investigate the paracrine interactions between prostate cancer (PCa) cells and human osteoblasts. Co-culture of the human PCa, LNCaP cells embedded within polyethylene glycol hydrogels with human osteoblasts in the form of a tissue engineered bone construct (TEB), resulted in reduced proliferation of LNCaP cells. LNCaP cells in both monoculture and co-culture were responsive to the androgen analog, R1881, as indicated by an increase in the expression (mRNA and/or protein induction) of androgen-regulated genes including prostate specific antigen and fatty acid synthase. Microarray gene expression analysis further revealed an up-regulation of bone markers and other genes associated with skeletal and vasculature development and a significant activation of transforming growth factor β1 downstream genes in LNCaP cells after co-culture with TEB. LNCaP cells co-cultured with TEB also unexpectedly showed similar changes in classical androgen-responsive genes under androgen-deprived conditions not seen in LNCaP monocultures. The molecular changes of LNCaP cells after co-culturing with TEBs suggest that osteoblasts exert a paracrine effect that may promote osteomimicry and modulate the expression of androgen-responsive genes in LNCaP cells. Taken together, we have presented a novel 3D in vitro model that allows the study of cellular and molecular changes occurring in PCa cells and osteoblasts that are relevant to metastatic colonization of bone. This unique in vitro model could also facilitate cancer biologists to dissect specific biological hypotheses via extensive genomic or proteomic assessments to further our understanding of the PCa-bone crosstalk.

Gallotannin imposes S phase arrest in breast cancer cells and suppresses the growth of triple-negative tumors in vivo

Triple-negative breast cancers are associated with poor clinical outcomes and new therapeutic strategies are clearly needed. Gallotannin (Gltn) has been previously demonstrated to have potent anti-tumor properties against cholangiocarcinoma in mice, but little is known regarding its capacity to suppress tumor outgrowth in breast cancer models. We tested Gltn for potential growth inhibitory properties against a variety of breast cancer cell lines in vitro. In particular, triple-negative breast cancer cells display higher levels of sensitivity to Gltn. The loss of proliferative capacity in Gltn exposed cells is associated with slowed cell cycle progression and S phase arrest, dependent on Chk2 phosphorylation and further characterized by changes to proliferation related genes, such as cyclin D1 (CcnD1) as determined by Nanostring technology. Importantly, Gltn administered orally or via intraperitoneal (IP) injections greatly reduced tumor outgrowth of triple-negative breast cells from mammary fat pads without signs of toxicity. In conclusion, these data strongly suggest that Gltn represents a novel approach to treat triple-negative breast carcinomas.

Organized proteomic heterogeneity in colorectal cancer liver metastases and implications for therapies

Tumor heterogeneity is a major obstacle for developing effective anticancer treatments. Recent studies have pointed to large stochastic genetic heterogeneity within cancer lesions, where no pattern seems to exist that would enable a more structured targeted therapy approach. Because to date no similar information is available at the protein (phenotype) level, we employed matrix assisted laser desorption ionization (MALDI) image-guided proteomics and explored the heterogeneity of extracellular and membrane subproteome in a unique collection of eight fresh human colorectal carcinoma (CRC) liver metastases. Monitoring the spatial distribution of over 1,000 proteins, we found unexpectedly that all liver metastasis lesions displayed a reproducible, zonally delineated pattern of functional and therapeutic biomarker heterogeneity. The peritumoral region featured elevated lipid metabolism and protein synthesis, the rim of the metastasis displayed increased cellular growth, movement, and drug metabolism, whereas the center of the lesion was characterized by elevated carbohydrate metabolism and DNA-repair activity. From the aspect of therapeutic targeting, zonal expression of known and novel biomarkers was evident, reinforcing the need to select several targets in order to achieve optimal coverage of the lesion. Finally, we highlight two novel antigens, LTBP2 and TGFBI, whose expression is a consistent feature of CRC liver metastasis. We demonstrate their in vivo antibody-based targeting and highlight their potential usefulness for clinical applications.

CONCLUSION

The proteome heterogeneity of human CRC liver metastases has a distinct, organized pattern. This particular hallmark can now be used as part of the strategy for developing rational therapies based on multiple sets of targetable antigens.

TGFβ-mediated suppression of CD248 in non-cancer cells via canonical Smad-dependent signaling pathways is uncoupled in cancer cells

Background

CD248 is a cell surface glycoprotein, highly expressed by stromal cells and fibroblasts of tumors and inflammatory lesions, but virtually undetectable in healthy adult tissues. CD248 promotes tumorigenesis, while lack of CD248 in mice confers resistance to tumor growth. Mechanisms by which CD248 is downregulated are poorly understood, hindering the development of anti-cancer therapies.

Methods

We sought to characterize the molecular mechanisms by which CD248 is downregulated by surveying its expression in different cells in response to cytokines and growth factors.

Results

Only transforming growth factor (TGFβ) suppressed CD248 protein and mRNA levels in cultured fibroblasts and vascular smooth muscle cells in a concentration- and time-dependent manner. TGFβ transcriptionally downregulated CD248 by signaling through canonical Smad2/3-dependent pathways, but not via mitogen activated protein kinases p38 or ERK1/2. Notably, cancer associated fibroblasts (CAF) and cancer cells were resistant to TGFβ mediated suppression of CD248.

Conclusions

The findings indicate that decoupling of CD248 regulation by TGFβ may contribute to its tumor-promoting properties, and underline the importance of exploring the TGFβ-CD248 signaling pathway as a potential therapeutic target for early prevention of cancer and proliferative disorders.

BIGH3 modulates adhesion and migration of hematopoietic stem and progenitor cells

Cell adhesion and migration are important determinants of homing and development of hematopoietic stem and progenitor cells (HSPCs) in bone marrow (BM) niches. The extracellular matrix protein transforming growth factor-β (TGF-β) inducible gene H3 (BIGH3) is involved in adhesion and migration, although the effect of BIGH3 is highly cell type-dependent. BIGH3 is abundantly expressed by mesenchymal stromal cells, while its expression in HSPCs is relatively low unless induced by certain BM stressors. Here, we set out to determine how BIGH3 modulates HSPC adhesion and migration. We show that primary HSPCs adhere to BIGH3-coated substrates, which is, in part, integrin-dependent. Overexpression of BIGH3 in HSPCs and HL60 cells reduced the adhesion to the substrate fibronectin in adhesion assays, which was even more profound in electrical cell-substrate impedance sensing (ECIS) assays. Accordingly, the CXCL12 induced migration over fibronectin-coated surface was reduced in BIGH3-expressing HSPCs. The integrin expression profile of HSPCs was not altered upon BIGH3 expression. Although expression of BIGH3 did not alter actin polymerization in response to CXCL12, it inhibited the PMA-induced activation of the small GTPase RAC1 as well as the phosphorylation and activation of extracellular-regulated kinases (ERKs). Reduced activation of ERK and RAC1 may be responsible for the inhibition of cell adhesion and migration by BIGH3 in HSPCs. Induced BIGH3 expression upon BM stress may contribute to the regulation of BM homeostasis.

RecQL4 helicase amplification is involved in human breast tumorigenesis

Breast cancer occur both in hereditary and sporadic forms, and the later one comprises an overwhelming majority of breast cancer cases among women. Numerical and structural alterations involving chromosome 8, with loss of short arm (8p) and gain of long arm (8q), are frequently observed in breast cancer cells and tissues. In this study, we show that most of the human breast tumor cell lines examined display an over representation of 8q24, a chromosomal locus RecQL4 is regionally mapped to, and consequently, a markedly elevated level of RecQL4 expression. An increased RecQL4 mRNA level was also observed in a majority of clinical breast tumor samples (38/43) examined. shRNA-mediated RecQL4 suppression in MDA-MB453 breast cancer cells not only significantly inhibit the in vitro clonogenic survival and in vivo tumorigenicity. Further studies demonstrate that RecQL4 physically interacts with a major survival factor-survivin and its protein level affects survivin expression. Although loss of RecQL4 function due to gene mutations causally linked to occurrence of human RTS with features of premature aging and cancer predisposition, our studies provide the evidence that overexpression of RecQL4 due to gene amplification play a critical role in human breast tumor progression.

Melatonin induces autophagy via an mTOR-dependent pathway and enhances clearance of mutant-TGFBIp

The hallmark of granular corneal dystrophy type 2 (GCD2) is the deposit of mutant transforming growth factor-β (TGF-β)-induced protein (TGFBIp) in the cornea. We have recently shown that there is a delay in autophagic degradation of mutant-TGFBIp via impaired autophagic flux in GCD2 corneal fibroblasts. We hypothesized that melatonin can specifically induce autophagy and consequently eliminate mutant-TGFBIp in GCD corneal fibroblasts. Our results show that melatonin activates autophagy in both wild-type (WT) and GCD2-homozygous (HO) corneal fibroblast cell lines via the mammalian target of rapamycin (mTOR)-dependent pathway. Melatonin treatment also led to increased levels of beclin 1, which is involved in autophagosome formation and maturation. Furthermore, melatonin significantly reduced the amounts of mutant- and WT-TGFBIp. Treatment with melatonin counteracted the autophagy-inhibitory effects of bafilomycin A1, a potent inhibitor of autophagic flux, demonstrating that melatonin enhances activation of autophagy and increases degradation of TGFBIp. Cotreatment with melatonin and rapamycin, an autophagy inducer, had an additive effect on mutant-TGFBIp clearance compared to treatment with either drug alone. Treatment with the selective melatonin receptor antagonist luzindole did not block melatonin-induced autophagy. Given its ability to activate autophagy, melatonin is a potential therapeutic agent for GCD2.

Wnt3 function in the epiblast is required for the maintenance but not the initiation of gastrulation in mice

The formation of the anteroposterior axis in mice requires a Wnt3-dependent symmetry-breaking event that leads to the formation of the primitive streak and gastrulation. Wnt3 is expressed sequentially in two distinct areas of the mouse embryo before the appearance of the primitive streak; first in the posterior visceral endoderm and soon after in the adjacent posterior epiblast. Hence, although an axial requirement for Wnt3 is well established, its temporal and tissue specific requirements remain an open question. Here, we report the conditional inactivation of Wnt3 in the epiblast of developing mouse embryos. Contrary to previous studies, our data shows that embryos lacking Wnt3 specifically in the epiblast are able to initiate gastrulation and advance to late primitive streak stages but fail to thrive and are resorbed by E9.5. At the molecular level, we provide evidence that Wnt3 regulates its own expression and that of other primitive streak markers via activation of the canonical Wnt signaling pathway.

Systems analysis of a mouse xenograft model reveals annexin A1 as a regulator of gene expression in tumor stroma

Annexin A1 is a multi functional molecule which is involved in inflammation, innate and adaptive immune systems, tumor progression and metastasis. We have previously showed the impaired tumor growth, metastasis, angiogenesis and wound healing in annexin A1 knockout mice. While tumor is a piece of heterogeneous mass including not only malignant tumor cells but also the stroma, the importance of the tumor stroma for tumor progression and metastasis is becoming increasingly clear. The tumor stroma is comprised by various components including extracellular matrix and non-malignant cells in the tumor, such as endothelial cells, fibroblasts, immune cells, inflammatory cells. Based on our previous finding of pro-angiogenic functions for annexin A1 in vascular endothelial cell sprouting, wound healing, tumor growth and metastasis, and the previously known properties for annexin A1 in immune cells and inflammation, this study hypothesized that annexin A1 is a key functional player in tumor development, linking the various components in tumor stroma by its actions in endothelial cells and immune cells. Using systems analysis programs commercially available, this paper further compared the gene expression between tumors from annexin A1 wild type mice and annexin A1 knockout mice and found a list of genes that significantly changed in the tumor stroma that lacked annexin A1. This revealed annexin A1 to be an effective regulator in tumor stroma and suggested a mechanism that annexin A1 affects tumor development and metastasis through interaction with the various components in the microenvironment surrounding the tumor cells.

Matrix metalloproteinase 9 (MMP-9)-dependent processing of βig-h3 protein regulates cell migration, invasion, and adhesion

Cell migration is critically involved in inflammation, cancer, and development. In this study, transforming growth factor-β-induced protein (βig-h3) was identified as a substrate of matrix metalloproteinase-9 (MMP-9) by site-directed mutagenesis. βig-h3 has two cleavage sites with the consensus sequence Pro-Xaa-Xaa-Hy-(Ser/Thr) (Hy is a hydrophobic amino acid) (PGSFT beginning at amino acid 135 and PPMGT beginning at amino acid 501). Using recombinant human βig-h3 and MMP-9, βig-h3 from βig-h3-transfected HEK293F cells, and MMP-9 from MMP-9-transfected HEK293F cells, human macrophages, and neutrophils, we found that MMP-9 proteolytically cleaves βig-h3. Cleavage leads to the loss of its adhesive property and its release from extracellular matrix proteins, collagen IV, and fibronectin. Spheroids formed by increased cell-cell interactions were observed in βig-h3-transfected HEK293F cells but not in vehicle-transfected HEK293F cells. In human glioma U87MG cells, MMP-9 constitutive overexpression resulted in endogenous βig-h3 cleavage. βig-h3 cleavage by MMP-9 led to increased cell invasion, and βig-h3 knockdown also resulted in increased cell invasion. The βig-h3 fragment cleaved by MMP-9 could bind to the surface of macrophages, and it may play a role as a peptide chemoattractant by inducing macrophage migration via focal adhesion kinase/Src-mediated signal activation. Thus, intact βig-h3 is responsible for cell migration inhibition, cell-cell contact, and cell-extracellular matrix interaction. Experimental evidence indicates that MMP-9-cleaved βig-h3 plays a role in MMP-9-mediated tumor cell and macrophage migration.

Transforming growth Factor-Beta-Induced Protein (TGFBI)/(βig-H3): a matrix protein with dual functions in ovarian cancer

Transforming growth factor-beta-induced protein (TGFBI, also known as βig-H3 and keratoepithelin) is an extracellular matrix protein that plays a role in a wide range of physiological and pathological conditions including diabetes, corneal dystrophy and tumorigenesis. Many reports indicate that βig-H3 functions as a tumor suppressor. Loss of βig-H3 expression has been described in several cancers including ovarian cancer and promoter hypermethylation has been identified as an important mechanism for the silencing of the TGFBI gene. Our recent findings that βig-H3 is down-regulated in ovarian cancer and that high concentrations of βig-H3 can induce ovarian cancer cell death support a tumor suppressor role. However, there is also convincing data in the literature reporting a tumor-promoting role for βig-H3. We have shown βig-H3 to be abundantly expressed by peritoneal cells and increase the metastatic potential of ovarian cancer cells by promoting cell motility, invasion, and adhesion to peritoneal cells. Our findings suggest that βig-H3 has dual functions and can act both as a tumor suppressor or tumor promoter depending on the tumor microenvironment. This article reviews the current understanding of βig-H3 function in cancer cells with particular focus on ovarian cancer.

Targeted disruption of TGFBI in mice reveals its role in regulating bone mass and bone size through periosteal bone formation

Transforming growth factor-beta induced (TGFBI) and periostin are two closely related proteins in structure as well as in function. A previous study found that periostin positively regulates bone size. Here, we hypothesize that TGFBI has a similar function in bone development. To test this hypothesis, we employed TGFBI-deficient mice, which were generated by targeted disruption of the TGFBI gene. We bred these mice with C57BL/6J mice to generate homozygous TGFBI-deficient (TGFBI(-/-)) mice and homozygous wild-type littermates. All mice were raised to 12 weeks of age. Bone mass parameters were determined by PIXImus and micro-CT, bone strength parameters by three-point bending, and bone formation and resorption parameters by histomorphometry. We found that targeted disruption of TGFBI led to reduced body size, bone mass, bone size, and bone strength. This indicates that, like periostin, TGFBI also positively regulates bone size and that changes in bone size affect bone strength. Furthermore, there was also a significant decrease in periosteal, but not endosteal, bone formation rate of cortical bone in TGFBI(-/-) mice, suggesting that the observed effect of TGFBI on bone mass and bone size was largely caused by the effect of TGFBI on periosteal bone formation.

The role of TGFBI in mesothelioma and breast cancer: association with tumor suppression

Background

Transforming growth factor β induced (TGFBI) product, an extracellular matrix (ECM) protein, has been implicated as a putative tumor suppressor in recent studies. Our previous findings revealed that expression of TGFBI gene is down-regulated in a variety of cancer cell lines and clinical tissue samples. In this study, ectopic expression of TGFBI was used to ascertain its role as a tumor suppressor and to determine the underlying mechanism of mesothelioma and breast cancer.

Methods

Cells were stably transfected with pRc/CMV2-TGFBI and pRc/CMV2-empty vector with Lipofectamine Plus. Ectopic expression of TGFBI was quantified by using quantitative PCR and Western-blotting. Characterization of cell viability was assessed using growth curve, clonogenic survival and soft agar growth. The potential of tumor formation was evaluated by an in vivo mouse model. Cell cycle was analyzed via flow cytometry. Expressions of p21, p53, p16 and p14 were examined using Western-blotting. Senescent cells were sorted by using a Senescence β-Galactosidase Staining Kit. Telomerase activity was measured using quantitative telomerase detection kit.

Results

In this study, an ectopic expression of TGFBI in two types of cancer cell lines, a mesothelioma cell line NCI-H28 and a breast cancer cell line MDA-MB-231 was found to have reduced the cellular growth, plating efficiency, and anchorage-independent growth. The tumorigenicity of these cancer cell lines as determined by subcutaneous inoculation in nude mice was similarly suppressed by TGFBI expression. Likewise, TGFBI expression reduced the proportion of S-phase while increased the proportion of G1 phase in these cells. The redistribution of cell cycle phase after re-expression of TGFBI was correspondent with transiently elevated expression of p21 and p53. The activities of senescence-associated β-galactosidase and telomerase were enhanced in TGFBI-transfected cells.

Conclusion

Collectively, these results imply that TGFBI plays a suppressive role in the development of mesothelioma and breast cancer cells, possibly through inhibitions of cell proliferation, delaying of G1-S phase transition, and induction of senescence.

ß3 integrin modulates transforming growth factor beta induced (TGFBI) function and paclitaxel response in ovarian cancer cells

Background

The extracellular matrix (ECM) has a key role in facilitating the progression of ovarian cancer and we have shown recently that the secreted ECM protein TGFBI modulates the response of ovarian cancer to paclitaxel-induced cell death.

Results

We have determined TGFBI signaling from the extracellular environment is preferential for the cell surface αvß3 integrin heterodimer, in contrast to periostin, a TGFBI paralogue, which signals primarily via a ß1 integrin-mediated pathway. We demonstrate that suppression of ß1 integrin expression, in ß3 integrin-expressing ovarian cancer cells, increases adhesion to rTGFBI. In addition, Syndecan-1 and −4 expression is dispensable for adhesion to rTGFBI and loss of Syndecan-1 cooperates with the loss of ß1 integrin to further enhance adhesion to rTGFBI. The RGD motif present in the carboxy-terminus of TGFBI is necessary, but not sufficient, for SKOV3 cell adhesion and is dispensable for adhesion of ovarian cancer cells lacking ß3 integrin expression. In contrast to TGFBI, the carboxy-terminus of periostin, lacking a RGD motif, is unable to support adhesion of ovarian cancer cells. Suppression of ß3 integrin in SKOV3 cells increases resistance to paclitaxel-induced cell death while suppression of ß1 integrin has no effect. Furthermore, suppression of TGFBI expression stimulates a paclitaxel resistant phenotype while suppression of fibronectin expression, which primarily signals through a ß1 integrin-mediated pathway, increases paclitaxel sensitivity.

Conclusions

Therefore, different ECM components use distinct signaling mechanisms in ovarian cancer cells and in particular, TGFBI preferentially interacts through a ß3 integrin receptor mediated mechanism to regulate the response of cells to paclitaxel-induced cell death.

Release of TGFβig-h3 by gastric myofibroblasts slows tumor growth and is decreased with cancer progression

Tumor progression has been linked to changes in the stromal environment. Myofibroblasts are stromal cells that are often increased in tumors but their contribution to cancer progression is not well understood. Here, we show that the secretomes of myofibroblasts derived from gastric cancers [cancer-associated myofibroblasts (CAMs)] differ in a functionally significant manner from those derived from adjacent tissue [adjacent tissue myofibroblasts (ATMs)]. CAMs showed increased rates of migration and proliferation compared with ATMs or normal tissue myofibroblasts (NTMs). Moreover, conditioned medium (CM) from CAMs significantly stimulated migration, invasion and proliferation of gastric cancer cells compared with CM from ATMs or NTMs. Proteomic analysis of myofibroblast secretomes revealed decreased abundance of the extracellular matrix (ECM) adaptor protein like transforming growth factor-β-induced gene-h3 (TGFβig-h3) in CAMs, which was correlated with lymph node involvement and shorter survival. TGFβig-h3 inhibited IGF-II-stimulated migration and proliferation of both cancer cells and myofibroblasts, and suppressed IGF-II activation of p42/44 MAPkinase; TGFβig-h3 knockdown increased IGF-II- and CM-stimulated migration. Furthermore, administration of TGFβig-h3 inhibited myofibroblast-stimulated growth of gastric cancer xenografts. We conclude that stromal cells exert inhibitory as well as stimulatory effects on tumor cells; TGFβig-h3 is a stromal inhibitory factor that is decreased with progression of gastric cancers.

Transforming growth factor beta-induced (TGFBI) is an anti-adhesive protein regulating the invasive growth of melanoma cells

Melanoma is a malignancy characterized by high invasive/metastatic potential, with no efficient therapy after metastasis. Understanding the molecular mechanisms underlying the invasive/metastatic tendency is therefore important. Our genome-wide gene expression analyses revealed that human melanoma cell lines WM793 and especially WM239 (vertical growth phase and metastatic cells, respectively) overexpress the extracellular matrix (ECM) protein transforming growth factor β induced (TGFBI). In adhesion assays, recombinant TGFBI was strongly anti-adhesive for both melanoma cells and skin fibroblasts. TGFBI further impaired the adhesion of melanoma cells to the adhesive ECM proteins fibronectin, collagen-I, and laminin, known to interact with it. Unexpectedly, WM239 cells migrated/invaded more effectively in three-dimensional collagen-I and Matrigel cultures after knockdown of TGFBI by shRNA expression. However, in the physiological subcutaneous microenvironment in nude mice, after TGFBI knockdown, these cells showed markedly impaired tumor growth and invasive capability; the initially formed small tumors later underwent myxoid degeneration and completely regressed. By contrast, the expanding control tumors showed intense TGFBI staining at the tumor edges, co-localizing with the fibrillar fibronectin/tenascin-C/periostin structures that characteristically surround melanoma cells at invasion fronts. Furthermore, TGFBI was found in similar fibrillar structures in clinical human melanoma metastases as well, co-localizing with fibronectin. These data imply an important role for TGFBI in the ECM deposition and invasive growth of melanoma cells, rendering TGFBI a potential target for therapeutic interventions.

Proteomic identification of betaig-h3 as a lysophosphatidic acid-induced secreted protein of human mesenchymal stem cells: paracrine activation of A549 lung adenocarcinoma cells by betaig-h3

Lysophosphatidic acid (LPA) is enriched in the serum and malignant effusion of cancer patients and plays a key role in tumorigenesis and metastasis. LPA-activated mesenchymal stem cells promote tumorigenic potentials of cancer cells through a paracrine mechanism. LPA-conditioned medium (LPA CM) from human adipose tissue-derived mesenchymal stem cells (hASCs) elicited adhesion and proliferation of A549 human lung adenocarcinoma cells. To identify proteins involved in the LPA-stimulated paracrine functions of hASCs, we analyzed the LPA CM using liquid-chromatography tandem mass spectrometry-based shotgun proteomics. We identified βig-h3, an extracellular matrix protein that is implicated in tumorigenesis and metastasis, as an LPA-induced secreted protein in hASCs. LPA-induced βig-h3 expression was abrogated by pretreating hASCs with the LPA receptor(1/3) inhibitor Ki16425 or small interfering RNA-mediated silencing of endogenous LPA(1). LPA-induced βig-h3 expression was blocked by treating the cells with the Rho kinase inhibitor Y27632, implying that LPA-induced βig-h3 expression is mediated by the LPA(1)- Rho kinase pathway. Immunodepletion or siRNA-mediated silencing of βig-h3 abrogated LPA CM-stimulated adhesion and proliferation of A549 cells, whereas retroviral overexpression of βig-h3 in hASCs potentiated it. Furthermore, recombinant βig-h3 protein stimulated the proliferation and adhesion of A549 human lung adenocarcinoma cells. These results suggest that hASC-derived βig-h3 plays a key role in tumorigenesis by stimulating the adhesion and proliferation of cancer cells and it can be applicable as a biomarker and therapeutic target for lung cancer.

Transforming growth factor-β-induced protein (TGFBI) suppresses mesothelioma progression through the Akt/mTOR pathway

As an uncommon cancer, mesothelioma is very hard to treat with a low average survival rate owing to its usual late detection and being highly invasive. The link between asbestos exposure and the development of mesothelioma in humans is unequivocal. TGFBI, a secreted protein that is induced by transforming growth factor-β in various human cell types, has been shown to be associated with tumorigenesis in various types of tumors. It has been demonstrated that TGFBI expression is markedly suppressed in asbestos-induced tumorigenic cells, while an ectopic expression of TGFBI significantly suppresses tumorigenicity and progression in human bronchial epithelial cells. In order to delineate a potential role of TGFBI in mediating the molecular events that occur in mesothelioma tumorigenesis, we generated stable TGFBI knockdown mutants from the mesothelium cell line Met-5A by using an shRNA approach, and secondly created ectopic TGFBI overexpression mutants from the mesothelioma cell line H28 in which TGFBI is absent. We observed that in the absence of TGFBI, the knockdown mesothelial and mesothelioma cell lines exhibited an elevated proliferation rate, enhanced plating efficiency, increased anchorage-independent growth, as well as an increased cellular protein synthesis rate as compared with their respective controls. Furthermore, cell cycle regulatory proteins c-myc/cyclin D1/phosphor-Rb were upregulated; a more active PI3K/Akt/mTOR signaling pathway was also detected in TGFBI-depleted cell lines. These findings suggest that TGFBI may repress mesothelioma tumorigenesis and progression via the PI3K/Akt signaling pathway.

TGFBI expression reduces in vitro and in vivo metastatic potential of lung and breast tumor cells

Controversy has arisen as to the role of transforming growth factor-β-induced protein (TGFBI) in the regulation of tumor metastasis. Using lung and breast cancer cell lines (H522 and MCF-7, respectively), we established that TGFBI induced cell adhesion to extracellular matrix proteins by activating adhesion-associated signaling and subsequent structure reformation, ultimately leading to cells less motile; whereas TGFBI reduced abilities of colony formation in soft agar, penetration through matrix gel, and activation of matrix metalloproteinases 2 and 9. Furthermore, injection of TGFBI-expressing cells into immuno-deficient mice resulted in a significant reduction in tumor metastasis in vivo. Taken together, these data suggest that TGFBI moderates the metastatic potential of cancer cells.

CD248 facilitates tumor growth via its cytoplasmic domain

Background

Stromal fibroblasts participate in the development of a permissive environment for tumor growth, yet molecular pathways to therapeutically target fibroblasts are poorly defined. CD248, also known as endosialin or tumor endothelial marker 1 (TEM1), is a transmembrane glycoprotein expressed on activated fibroblasts. We recently showed that the cytoplasmic domain of CD248 is important in facilitating an inflammatory response in a mouse model of arthritis. Others have reported that CD248 gene inactivation in mice results in dampened tumor growth. We hypothesized that the conserved cytoplasmic domain of CD248 is important in regulating tumor growth.

Methods

Mice lacking the cytoplasmic domain of CD248 (CD248^CyD/CyD) were generated and evaluated in tumor models, comparing the findings with wild-type mice (CD248^WT/WT).

Results

As compared to the response in CD248^WT/WT mice, growth of T241 fibrosarcomas and Lewis lung carcinomas was significantly reduced in CD248^CyD/CyD mice. Tumor size was similar to that seen with CD248-deficient mice. Conditioned media from CD248^CyD/CyD fibroblasts were less effective at supporting T241 fibrosarcoma cell survival. In addition to our previous observation of reduced release of activated matrix metalloproteinase (MMP)-9, CD248^CyD/CyD fibroblasts also had impaired PDGF-BB-induced migration and expressed higher transcripts of tumor suppressor factors, transgelin (SM22α), Hes and Hey1.

Conclusions

The multiple pathways regulated by the cytoplasmic domain of CD248 highlight its potential as a therapeutic target to treat cancer.

Accessible chromatin structure permits factors Sp1 and Sp3 to regulate human TGFBI gene expression

Transforming growth factor beta 1-induced (TGFBI) protein is an extracellular matrix (ECM) protein that is associated with other ECM proteins and functions as a ligand for various types of integrins. In this study, we investigated how human TGFBI expression is regulated in lung and breast cancer cells. We observed that the TGFBI promoter in A549 and MBA-MD-231 cells, which constitutively express TGFBI, existed in an open chromatin conformation associated with transcriptionally permissive histone modifications. Moreover, we found that TGFBI expression required Sp1 transcription elements that can bind transcription factors Sp1 and Sp3 in vitro. Occupancy of the TGFBI promoter by Sp1 and Sp3 in vivo was only observed in TGFBI-expressing cells, indicating that open chromatin conformation might facilitate the binding of Sp1 and Sp3 to the TGFBI promoter region. TGFBI promoter activity was impaired when Sp1 elements were mutated, but was increased when Sp1 or Sp3 factors was overexpressed. Furthermore, Sp1 inhibition in vivo by mithramycin A, as well as knockdown of Sp1 and/or Sp3 expression by short interfering RNA, significantly reduced TGFBI mRNA and protein levels. Thus, our data demonstrated that the expression of TGFBI is well correlated with chromatin conformation at the TGFBI promoter, and that factors Sp1 and Sp3 are the primary determinants for the control of constitutive expression of TGFBI gene.

MiR-21 plays an important role in radiation induced carcinogenesis in BALB/c mice by directly targeting the tumor suppressor gene Big-h3

Dysregulation of certain microRNAs (miRNAs) in cancer can promote tumorigenesis, metastasis and invasion. However, the functions and targets of only a few mammalian miRNAs are known. In particular, the miRNAs that participates in radiation induced carcinogenesis and the miRNAs that target the tumor suppressor gene Big-h3 remain undefined. Here in this study, using a radiation induced thymic lymphoma model in BALB/c mice, we found that the tumor suppressor gene Big-h3 is down-regulated and miR-21 is up-regulated in radiation induced thymic lymphoma tissue samples. We also found inverse correlations between Big-h3 protein and miR-21 expression level among different tissue samples. Furthermore, our data indicated that miR-21 could directly target Big-h3 in a 3′UTR dependent manner. Finally, we found that miR-21 could be induced by TGFβ, and miR-21 has both positive and negative effects in regulating TGFβ signaling. We conclude that miR-21 participates in radiation induced carcinogenesis and it regulates TGFβ signaling.

Association of chromosome damage detected as micronuclei with hematological diseases and micronutrient status

Epidemiological studies reveal strong association between micronutrient deficiencies and development of cancer. Since chromosome breaks and abnormal chromosome segregation, identified as micronuclei (MN), are central to malignant transformation, the influence of micronutrient status upon MN frequency has been the subject of intense research. Motivating this effort is the idea that marginal micronutrient deficiencies lead to allocation of scarce cellular resources towards immediate survival at the expense of maintaining genomic integrity, placing the individual at greater risk for degenerative diseases and cancer in old age. The challenge in identifying an association between individual micronutrients and MN frequency stems from the complexity of human diet, simultaneous presence of multiple micronutrient deficiencies, variable genetic susceptibility and methodological difficulties. A unique model for studying MN in humans is provided by a group of haematological diseases, the chronic haemolytic anaemias associated with high reticulocyte count and absence of splenic function. These disorders may prove valuable for assessing the influence of micronutrient status once the effect of abnormal erythropoiesis on MN formation is adequately understood. Eventually, large population-based studies that can account for the baseline variability in MN frequency, lifestyle and genetic factors may be needed to uncover the DNA-damaging effect of poor diet. Understanding the link between micronutrient status and MN frequency will contribute towards determining optimal micronutrient intake to preserve long-term health.

TGFB1-induced extracellular expression of TGFBIp and inhibition of TGFBIp expression by RNA interference in a human corneal epithelial cell line

PURPOSE

To report the increased production of extracellular transforming growth factor β-induced protein (TGFBIp) by human corneal epithelial cells (HCECs) after induction by TGFB1 and the inhibition of TGFBIp production in induced and noninduced HCECs by RNA interference (RNAi).

METHODS

HCECs were cultured in serum-free medium and treated with 0 or 10 ng/mL TGFB1 over a period of 72 hours. Commercially available siRNAs targeting TGFBI mRNA were mixed with a transfection reagent and used to reverse transfect TGFB1-induced and noninduced HCECs. Extracellular and intracellular concentrations of TGFBIp were measured by ELISA and Western blot analysis, respectively, and TGFBI RNA was assayed using semiquantitative RT-PCR.

RESULTS

HCECs constitutively express TGFBIp, and treatment with TGFB1 results in up to a fourfold increase in the amount of extracellular TGFBIp. Four commercially available siRNAs targeting TGFBI mRNA produced a >70% decrease in extracellular TGFBIp within 48 hours after transfection of noninduced HCECs but a <25% decrease in extracellular TGFBIp by 48 hours after transfection of TGFB1-induced HCECs. The suppression of extracellular TGFBIp production correlated with a decrease in intracellular TGFBIp production and TGFBI mRNA expression after transfection.

CONCLUSIONS

Extracellular TGFBIp expression by HCECs is increased several fold after exposure to TGFB1. Both HCEC-constitutive and HCEC-induced TGFBIp production can be inhibited with RNA interference, though the effect was greater and lasted longer for constitutive than induced TGFBIp production. Given that the corneal deposits in the TGFBI dystrophies consist of TGFBIp derived from HCECs, RNAi represents a potential means to inhibit primary dystrophic deposit formation and recurrence after surgical intervention.

Identification of PITX1 as a TERT suppressor gene located on human chromosome 5

Telomerase, a ribonucleoprotein enzyme that maintains telomere length, is crucial for cellular immortalization and cancer progression. Telomerase activity is attributed primarily to the expression of telomerase reverse transcriptase (TERT). Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line B16F10, we previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression (H. Kugoh, K. Shigenami, K. Funaki, J. Barrett, and M. Oshimura, Genes Chromosome Cancer 36:37-47, 2003). To identify the gene responsible for the regulation of TERT transcription, we performed cDNA microarray analysis using parental B16F10 cells, telomerase-negative B16F10 microcell hybrids with a human chromosome 5 (B16F10MH5), and its revertant clones (MH5R) with reactivated telomerase. Here, we report the identification of PITX1, whose expression leads to the downregulation of mouse tert (mtert) transcription, as a TERT suppressor gene. Additionally, both human TERT (hTERT) and mouse TERT (mtert) promoter activity can be suppressed by PITX1. We show that three and one binding site within the hTERT and mtert promoters, respectively, that express a unique conserved region are responsible for the transcriptional activation of TERT. Furthermore, we showed that PITX1 binds to the TERT promoter both in vitro and in vivo. Thus, PITX1 suppresses TERT transcription through direct binding to the TERT promoter, which ultimately regulates telomerase activity.

Global transcriptome analysis of human bone marrow stromal cells (BMSC) reveals proliferative, mobile and interactive cells that produce abundant extracellular matrix proteins, some of which may affect BMSC potency

BACKGROUND AIMS

Bone marrow stromal cells (BMSC) are being used for immune modulatory, anti-inflammatory and tissue engineering applications, but the properties responsible for these effects are not completely understood. Human BMSC were characterized to identify factors that might be responsible for their clinical effects and biomarkers for assessing their quality.

METHODS

Early passage BMSC prepared from marrow aspirates of seven healthy subjects were compared with three human embryonic stem cell (hESC) samples, CD34(+) cells from three healthy subjects and three fibroblast cell lines. The cells were analyzed with oligonucleotide expression microarrays with more than 35 000 probes.

RESULTS

BMSC gene expression signatures of BMSC differed from those of hematopoietic stem cells (HSC), hESC and fibroblasts. Genes upregulated in BMSC were involved with cell movement, cell-to-cell signaling and interaction and proliferation. The upregulated genes most probably belonged to pathways for integrin signaling, integrin-linked kinase (ILK) signaling, NF-E2-related factor-2 (NFR2)-mediated oxidative stress response, regulation of actin-based motility by Rho, actin cytoskeletal signaling, caveolar-mediated endocytosis, clathrin-mediated endocytosis and Wingless-type MMTV integration site (Wnt/β catenin signaling. Among the most highly upregulated genes were structural extracellular matrix (ECM) proteins (α5 and β5 integrin chains, fibronectin and collagen type IIIα1 and Vα1) and functional EMC proteins [connective tissue growth factor (CTGF), transforming growth factor beta-induced protein (TGFBI) and A disintegrin and metalloproteinase (ADAM12)].

CONCLUSIONS

Global analysis of human BMSC suggests that they are mobile, metabolically active, proliferative and interactive cells that make use of integrins and integrin signaling. They produce abundant ECM proteins that may contribute to their clinical immune modulatory and anti-inflammatory effects.

Mechanism of radiation carcinogenesis: role of the TGFBI gene and the inflammatory signaling cascade

Using an immortalized human bronchial epithelial cell line, we showed previously that the transforming growth factor beta-induced (TGFBI) gene was consistently downregulated by six- to sevenfold among radiation-induced tumorigenic human cells when compared with controls. Transfection of TGFBI gene into tumor cells resulted in a significant reduction in tumor growth as well as in vitro anchorage independent growth. The observations that TGFBI knock-out animals showed increased spontaneous tumor incidence and chemically induced tumors highlight the suppressive nature of the gene. There is evidence that extranuclear/extracellular targets are important in low-dose radiation response and that the cyclo-oxygenase-2 signaling pathway mediates the process. The involvement of NFκB-dependent cytokines and the resultant inflammatory response works in concert with in modulating radiation-induced bronchial carcinogenesis.

Transforming properties of 8p11-12 amplified genes in human breast cancer

Amplification of the 8p11-12 region has been found in about 15% of human breast cancers and is associated with poor prognosis. Earlier, we used genomic analysis of copy number and gene expression to perform a detailed analysis of the 8p11-12 amplicon to identify candidate oncogenes in breast cancer. We identified 21 candidate genes and provided evidence that three genes, namely, LSM-1, TC-1, and BAG4, have transforming properties when overexpressed. In the present study, we systematically investigated the transforming properties of 13 newly identified 8p11-12 candidate oncogenes in vitro. WHSC1L1, DDHD2, and ERLIN2 were most potently transforming oncogenes based on the number of altered phenotypes expressed by the cells. WHSC1L1 contains a PWWP-domain that is a methyl-lysine recognition motif involved in histone code modification and epigenetic regulation of gene expression. Knockdown of WHSC1L1 in 8p11-12-amplified breast cancer cells resulted in profound loss of growth and survival of these cells. Further, we identified several WHSC1L1 target genes, one of which is iroquois homeobox 3 gene (IRX3), a member of the Iroquois homeobox transcription factor family.

Prevention of mutation, cancer, and other age-associated diseases by optimizing micronutrient intake

I review three of our research efforts which suggest that optimizing micronutrient intake will in turn optimize metabolism, resulting in decreased DNA damage and less cancer as well as other degenerative diseases of aging. (1) Research on delay of the mitochondrial decay of aging, including release of mutagenic oxidants, by supplementing rats with lipoic acid and acetyl carnitine. (2) The triage theory, which posits that modest micronutrient deficiencies (common in much of the population) accelerate molecular aging, including DNA damage, mitochondrial decay, and supportive evidence for the theory, including an in-depth analysis of vitamin K that suggests the importance of achieving optimal micronutrient intake for longevity. (3) The finding that decreased enzyme binding constants (increased Km) for coenzymes (or substrates) can result from protein deformation and loss of function due to an age-related decline in membrane fluidity, or to polymorphisms or mutation. The loss of enzyme function can be compensated by a high dietary intake of any of the B vitamins, which increases the level of the vitamin-derived coenzyme. This dietary remediation illustrates the importance of understanding the effects of age and polymorphisms on optimal micronutrient requirements. Optimizing micronutrient intake could have a major effect on the prevention of cancer and other degenerative diseases of aging.

Transcriptional regulation of Wnt inhibitory factor-1 by Miz-1/c-Myc

The Wnt signaling pathway is capable of self-regulation through positive and negative feedback mechanisms. For example, the oncoprotein c-Myc, which is upregulated by Wnt signaling activity, participates in a positive feedback loop of canonical Wnt signaling through repression of Wnt antagonists DKK1 and SFRP1. In this study, we investigated the mechanism of Wnt inhibitory factor-1 (WIF-1) silencing. Mapping of CpG island methylation of the WIF-1 promoter reveals regional methylation (-295 to -95 bp from the transcription start site) that correlates with transcriptional silencing. We identified Miz-1 as a direct activator of WIF-1 transcriptional activity, which is found at WIF-1 promoter. In addition, we show that c-Myc contributes to WIF-1 transcriptional repression in a Miz-1-dependent manner. Although the transient repression mediated by Miz-1/c-Myc is independent of de novo methylation, the stable repression by this complex is associated with CpG island methylation of the critical -295 to -95-bp region of the WIF-1 promoter. Importantly, Miz-1 and c-Myc are found at WIF-1 promoter in WIF-1 non-expressing cell lines DLD-1 and 209myc. Transient knockdown or somatic knockout of c-Myc in DLD-1 failed to restore WIF-1 expression suggesting that c-Myc is involved in initiating rather than maintaining WIF-1 epigenetic silencing. In a genome-wide screen, DNAJA4, TGFβ-induced and TRIM59 were repressed by c-Myc overexpression and DNA promoter hypermethylation. Our data reveal novel insights into c-Myc-mediated DNA methylation-dependent transcriptional silencing, a mechanism that might contribute to the dysregulation of Wnt signaling in cancer.

Transforming growth factor-beta-induced protein secreted by peritoneal cells increases the metastatic potential of ovarian cancer cells

Ovarian cancer metastasis is characterized by the shedding of malignant cells from the surface of the ovary and their implantation onto the peritoneal surface, which lines the abdominal cavity. As the factors promoting this process are poorly understood, we investigated the ovarian cancer-peritoneal interaction by means of in vitro coculture experiments with ovarian cancer (OVCAR-5 and SKOV-3) and peritoneal (LP-9) cells. One of the proteins differentially expressed in the coculture secretome was identified by MALDI-TOF/TOF mass spectrometry as the extracellular matrix protein transforming growth factor-beta-induced protein (TGFBIp, also known as βig-H3). Immunohistochemistry showed high TGFBIp levels in normal surface ovarian epithelial and peritoneal cells, whereas TGFBIp levels in primary serous ovarian carcinomas and matching metastatic implants was very low. In functional in vitro experiments, treatment with recombinant TGFBIp significantly increased the motility and invasiveness of OVCAR-5 and SKOV-3 cells and significantly increased ovarian cancer cell (OVCAR-5, OVCAR-3 and SKOV-3) adhesion to LP-9 cells. TGFBIp was found to be processed at both the N- and C-terminus in the secretome of the ovarian cancer-peritoneal cell coculture. Plasmin inhibitors blocked TGFBIp processing and significantly reduced OVCAR-5 cell adhesion to peritoneal cells. We conclude that TGFBIp expressed by peritoneal cells increases the metastatic potential of ovarian cancer cells. TGFBIp is therefore a potential novel therapeutic target against ovarian cancer.

TGFBI expression is associated with a better response to chemotherapy in NSCLC

BACKGROUND

Lung cancer is one of the most prevalent neoplasias in developed countries. Advances in patient survival have been limited and the identification of prognostic molecules is needed. Resistance to treatment is strongly related to tumor cell adhesion to the extracellular matrix and alterations in the quantity and nature of molecules constituting the tumor cell niche. Recently, transforming growth factor beta-induced protein (TGFBI), an extracellular matrix adaptor protein, has been reported to be differentially expressed in transformed tissues. Loss of TGFBI expression has been described in several cancers including lung carcinoma, and it has been suggested to act as a tumor suppressor gene.

RESULTS

To address the importance of TGFBI expression in cancer progression, we determined its expression in NSCLC clinical samples using immunohistochemistry. We identified a strong association between elevated TGFBI expression and the response to chemotherapy. Furthermore, we transiently over-expressed and silenced TGFBI in human NSCLC cell lines. Cells over-expressing TGFBI displayed increased sensitivity to etoposide, paclitaxel, cisplatin and gemcitabine. We observed that TGFBI-mediated induction of apoptosis occurred through its binding to alphavbeta3 integrin. We also determined that full-length TGFBI did not induce caspase 3/7 activation but its proteolytic fragments that were < 3 kDa in size, were able to activate caspase 3, 7 and 8. This pro-apoptotic effect was blocked by anti-alphavbeta3 integrin antibodies.

CONCLUSIONS

The results shown here indicate that TGFBI is a predictive factor of the response to chemotherapy, and suggest the use of TGFBI-derived peptides as possible therapeutic adjuvants for the enhancement of responses to chemotherapy.

Periostin shows increased evolutionary plasticity in its alternatively spliced region

Background

Periostin (POSTN) is a secreted extracellular matrix protein of poorly defined function that has been related to bone and heart development as well as to cancer. In human and mouse, it is known to undergo alternative splicing in its C-terminal region, which is devoid of known protein domains. Differential expression of periostin, sometimes of specific splicing isoforms, is observed in a broad range of human cancers, including breast, pancreatic, and colon cancer. Here, we combine genomic and transcriptomic sequence data from vertebrate organisms to study the evolution of periostin and particularly of its C-terminal region.

Results

We found that the C-terminal part of periostin is markedly more variable among vertebrates than the rest of periostin in terms of exon count, length, and splicing pattern, which we interpret as a consequence of neofunctionalization after the split between periostin and its paralog transforming growth factor, beta-induced (TGFBI). We also defined periostin's sequential 13-amino acid repeat units - well conserved in teleost fish, but more obscure in higher vertebrates - whose secondary structure is predicted to be consecutive beta strands. We suggest that these beta strands may mediate binding interactions with other proteins through an extended beta-zipper in a manner similar to the way repeat units in bacterial cell wall proteins have been reported to bind human fibronectin.

Conclusions

Our results, obtained with the help of the increasingly large collection of complete vertebrate genomes, document the evolutionary plasticity of periostin's C-terminal region, and for the first time suggest a basis for its functional role.

Expression analysis of human pterygium shows a predominance of conjunctival and limbal markers and genes associated with cell migration

PURPOSE

Pterygium is a vision-impairing fibrovascular lesion that grows across the corneal surface and is associated with sunlight exposure. To increase our understanding of the cells types involved in pterygium, we have used expressed sequence tag analysis to examine the transcriptional repertoire of isolated pterygium and to identify marker genes for tissue origin and cell migration.

METHODS

An unnormalized unamplified cDNA library was prepared from 15 pooled specimens of surgically removed pterygia as part of the NEIBank project. Gene expression patterns were compared with existing data for human cornea, limbus, and conjunctiva, and expression of selected genes was verified by immunofluorescence localization in normal eye ocular surface and in pterygium.

RESULTS

Sequence analysis of 2,976 randomly selected clones produced over 1,800 unique clusters, potentially representing single genes. The most abundant complementary DNAs from pterygium include clusterin, keratins 13 (Krt13) and 4 (Krt4), S100A9/calgranulin B, and spermidine/spermine N1-acetyltransferase (SAT1). Markers for both conjunctiva (such as keratin 13/4 and AQP3) and corneal epithelium (such as keratin 12/3 and AQP5) were present. Immunofluorescence of Krt12 and 13 in the normal ocular surface showed specificity of Krt12 in cornea and Krt13 in conjunctival and limbal epithelia, with a fairly sharp boundary at the limbal-corneal border. In the pterygium there was a patchy distribution of both Krt12 and 13 up to a normal corneal epithelial region specific for Krt12. Immunoglobulins were also among the prominently expressed transcripts. Several of the genes expressed most abundantly in excised pterygium, particularly S100A9 and SAT1, have roles in cell migration. SAT1 exerts its effects through control of polyamine levels. IPENSpm, a polyamine analogue, showed a significant ability to reduce migration in primary cultures of pterygium. A number of genes highly expressed in cornea were not found in pterygium (several small leucine-rich proteoglycan family members) or were expressed at considerably lower levels (ALDH3A1 and decorin).

CONCLUSIONS

The expression pattern of keratins and other markers in pterygium most closely resemble those of conjunctival and limbal cells; some corneal markers are present, notably Krt12, but at lower levels than equivalent conjunctival markers. Our data are consistent with the model of pterygium developing from the migration of conjunctival- and limbal-like cells into corneal epithelium. Identification of genes with roles in cell migration suggests potential therapeutic targets. In particular, the ability of polyamine analogues to reduce migration in primary cultures of pterygium presents a possible approach to slowing pterygium growth.

Vitamin K, an example of triage theory: is micronutrient inadequacy linked to diseases of aging?

The triage theory posits that some functions of micronutrients (the approximately 40 essential vitamins, minerals, fatty acids, and amino acids) are restricted during shortage and that functions required for short-term survival take precedence over those that are less essential. Insidious changes accumulate as a consequence of restriction, which increases the risk of diseases of aging. For 16 known vitamin K-dependent (VKD) proteins, we evaluated the relative lethality of 11 known mouse knockout mutants to categorize essentiality. Results indicate that 5 VKD proteins that are required for coagulation had critical functions (knockouts were embryonic lethal), whereas the knockouts of 5 less critical VKD proteins [osteocalcin, matrix Gla protein (Mgp), growth arrest specific protein 6, transforming growth factor beta-inducible protein (Tgfbi or betaig-h3), and periostin] survived at least through weaning. The VKD gamma-carboxylation of the 5 essential VKD proteins in the liver and the 5 nonessential proteins in nonhepatic tissues sets up a dichotomy that takes advantage of the preferential distribution of dietary vitamin K1 to the liver to preserve coagulation function when vitamin K1 is limiting. Genetic loss of less critical VKD proteins, dietary vitamin K inadequacy, human polymorphisms or mutations, and vitamin K deficiency induced by chronic anticoagulant (warfarin/coumadin) therapy are all linked to age-associated conditions: bone fragility after estrogen loss (osteocalcin) and arterial calcification linked to cardiovascular disease (Mgp). There is increased spontaneous cancer in Tgfbi mouse knockouts, and knockdown of Tgfbi causes mitotic spindle abnormalities. A triage perspective reinforces recommendations of some experts that much of the population and warfarin/coumadin patients may not receive sufficient vitamin K for optimal function of VKD proteins that are important to maintain long-term health.

Intercellular communication of cellular stress monitored by gamma-H2AX induction

When cells are exposed to ionizing radiation (IR), unexposed cells that share media with damaged cells exhibit similar effects to irradiated cells including increased levels of DNA double-strand breaks (DSBs). Hypothesizing that this effect, known as the radiation-induced bystander effect, may be a specific instance of communication between damaged and undamaged cells regardless of damage source, we demonstrated that exposure of target cells to non-IR induces bystander damage in non-targeted cells as measured by gamma-H2AX and 53BP1 focal formation. Initially, bystander damage was found primarily in S-phase cells, but at later times, non-S-phase cells were also affected. In addition, media from undamaged malignant and senescent cells also was found to induce DSBs in primary cultures. Media conditioned on cells targeted with either ionizing or non-IR as well as on undamaged malignant and senescent cells contained elevated levels of several cytokines. One of these, transforming growth factor beta (TGF-beta), and nitric oxide (NO) were found to elevate numbers of gamma-H2AX/53BP1 foci in normal cell cultures similar to levels found in bystander cells, and this elevation was abrogated by NO synthase inhibitors, TGF-beta blocking antibody and antioxidants. These findings support the hypothesis that damage in bystander cells results from their exposure to cytokines or reactive compounds released from stressed cells, regardless of damage source. These results have implications for oncogenesis in that they indicate that damaged normal cells or undamaged tumor cells may induce genomic instability, leading to an increased risk of oncogenic transformation in other cells with which they share media or contact directly.

An essential role for DNA methyltransferase 3a in melanoma tumorigenesis

Abnormal DNA methylation and associated silencing of tumor suppressor genes are common to many types of cancers. Among the three coordinate DNA methyltransferases (Dnmts), Dnmt1 and Dnmt3b were both shown to be important for cancer cell survival and tumorigenesis. However, the relationship between Dnmt3a and tumorigenesis is still largely unknown. Here, we show that inhibition of Dnmt3a expression, by stable transfection of a Dnmt3a-RNA interference (RNAi) construct dramatically inhibited melanoma growth and metastasis in mouse melanoma models. Microarray analysis revealed that genes critical for the tumor immune response, were implicated in the inhibition of melanoma growth. Expression of a cluster of class I and class II MHC genes, class II transactivator (Ciita), as well as a subset of 5 chemokines (Cxcl9, Cxcl16, Ccl12, Ccl4, and Ccl2) were up-regulated. Furthermore, we determined that the promoter IV of Ciita was significantly demethylated in Dnmt3a-depleted tumors. In addition, several known tumor-related genes, which are critical for developmental processes and cell cycle, were confirmed to be misregulated, including TgfB1, Socs1, Socs2, E2F6, Ccne1, and Cyr61. The results presented in this report strongly suggest that Dnmt3a plays an essential role in melanoma tumorigenesis, and that the underlying mechanisms include the modulation of the tumor immune response, as well as other processes.

C-terminal fragment of transforming growth factor beta-induced protein (TGFBIp) is required for apoptosis in human osteosarcoma cells

Transforming growth factor beta-induced protein (TGFBIp), is secreted into the extracellular space. When fragmentation of C-terminal portions is blocked, apoptosis is low, even when the protein is overexpressed. If fragmentation occurs, apoptosis is observed. Whether full-length TGFBIp or integrin-binding fragments released from its C-terminus is necessary for apoptosis remains equivocal. More importantly, the exact portion of the C-terminus that conveys the pro-apoptotic property of TGFBIp is uncertain. It is reportedly within the final 166 amino acids. We sought to determine if this property is dependent upon the final 69 amino acids containing the integrin-binding, EPDIM and RGD, sequences. With MG-63 osteosarcoma cells, transforming growth factor (TGF)-beta1 treatment increased expression of TGFBIp over 72 h (p<0.001). At this time point, apoptosis was significantly increased (p<0.001) and was prevented by an anti-TGFBIp, polyclonal antibody (p<0.05). Overexpression of TGFBIp by transient transfection produced a 2-fold increase in apoptosis (p<0.01). Exogenous purified TGFBIp at concentrations of 37-150 nM produced a dose dependent increase in apoptosis (p<0.001). Mass spectrometry analysis of TGFBIp isolated from conditioned medium of cells treated with TGF-beta1 revealed truncated forms of TGFBIp that lacked integrin-binding sequences in the C-terminus. Recombinant TGFBIp truncated, similarly, at amino acid 614 failed to induce apoptosis. A recombinant fragment encoding the final 69 amino acids of the TGFBIp C-terminus produced significant apoptosis. This apoptosis level was comparable to that induced by TGF-beta1 upregulation of endogenous TGFBIp. Mutation of the integrin-binding sequence EPDIM, but not RGD, blocked apoptosis (p<0.001). These pro-apoptotic actions are dependent on the C-terminus most likely to interact with integrins.