Granulin-epithelin precursor is a novel prognostic marker in epithelial ovarian carcinoma

The granulin gene family: from cancer to dementia

The growth factor progranulin (PGRN) regulates cell division, survival, and migration. PGRN is an extracellular glycoprotein bearing multiple copies of the cysteine-rich granulin motif. With PGRN family members in plants and slime mold, it represents one of the most ancient of the extracellular regulatory proteins still extant in modern animals. PRGN has multiple biological roles. It contributes to the regulation of early embryogenesis, to adult tissue repair and inflammation. Elevated PGRN levels often occur in cancers, and PGRN immunotherapy inhibits the growth of hepatic cancer xenografts in mice. Recent studies have demonstrated roles for PGRN in neurobiology. An autosomal dominant mutation in GRN, the gene for PGRN, leads to neuronal atrophy in the frontal and temporal lobes, resulting in the disease frontotemporal lobar dementia. In this review we will discuss current knowledge of the multifaceted biology of PGRN.

Progranulin is expressed within motor neurons and promotes neuronal cell survival

BACKGROUND

Progranulin is a secreted high molecular weight growth factor bearing seven and one half copies of the cysteine-rich granulin-epithelin motif. While inappropriate over-expression of the progranulin gene has been associated with many cancers, haploinsufficiency leads to atrophy of the frontotemporal lobes and development of a form of dementia (frontotemporal lobar degeneration with ubiquitin positive inclusions, FTLD-U) associated with the formation of ubiquitinated inclusions. Recent reports indicate that progranulin has neurotrophic effects, which, if confirmed would make progranulin the only neuroprotective growth factor that has been associated genetically with a neurological disease in humans. Preliminary studies indicated high progranulin gene expression in spinal cord motor neurons. However, it is uncertain what the role of Progranulin is in normal or diseased motor neuron function. We have investigated progranulin gene expression and subcellular localization in cultured mouse embryonic motor neurons and examined the effect of progranulin over-expression and knockdown in the NSC-34 immortalized motor neuron cell line upon proliferation and survival.

RESULTS

In situ hybridisation and immunohistochemical techniques revealed that the progranulin gene is highly expressed by motor neurons within the mouse spinal cord and in primary cultures of dissociated mouse embryonic spinal cord-dorsal root ganglia. Confocal microscopy coupled to immunocytochemistry together with the use of a progranulin-green fluorescent protein fusion construct revealed progranulin to be located within compartments of the secretory pathway including the Golgi apparatus. Stable transfection of the human progranulin gene into the NSC-34 motor neuron cell line stimulates the appearance of dendritic structures and provides sufficient trophic stimulus to survive serum deprivation for long periods (up to two months). This is mediated at least in part through an anti-apoptotic mechanism. Control cells, while expressing basal levels of progranulin do not survive in serum free conditions. Knockdown of progranulin expression using shRNA technology further reduced cell survival.

CONCLUSION

Neurons are among the most long-lived cells in the body and are subject to low levels of toxic challenges throughout life. We have demonstrated that progranulin is abundantly expressed in motor neurons and is cytoprotective over prolonged periods when over-expressed in a neuronal cell line. This work highlights the importance of progranulin as neuroprotective growth factor and may represent a therapeutic target for neurodegenerative diseases including motor neuron disease.

Roles of progranulin in sexual differentiation of the developing brain and adult neurogenesis

Progranulin (PGRN) is a growth modulating factor released by a variety of cells. This molecule has gained the attention of the neuroscience community with recent discoveries of multifunctional roles of PGRN in normal brain and neurodegenerative disorders. We focus on novel roles of PGRN as a sex steroid-responsible gene in the developing and adult rodent brain. While the developing brain is feminine by default, hormone exposure, including androgen and estrogen, induces masculinization during the critical period. We have shown that PGRN is a sex steroid-responsible gene that may be involved in masculinization of the perinatal rat brain. We also found that in adult rats PGRN gene expression was up-regulated by estrogen in the hippocampus, suggesting that PGRN may mediate the mitogenic effects of estrogen in the active area of neurogenesis. Since it has been recently reported that mutations in PGRN gene are responsible for a type of frontotemporal lobar degeneration in humans, PGRN appears to be also involved in modulating neurodegeneration. Together, PGRN gene expression is induced by estrogen in both developing and adult brains, and it may play multifunctional roles in the organization of functional masculinization in the developing brain and the maintenance of adult brain function.

The emerging roles of ADAMTS-7 and ADAMTS-12 matrix metalloproteinases

The a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) comprise a family of secreted zinc metalloproteinases with a precisely ordered modular organization. These enzymes play an important role in the turnover of extracellular matrix proteins in various tissues and their dysregulation has been implicated in disease-related processes such as arthritis, atherosclerosis, cancer, and inflammation. ADAMTS-7 and ADAMTS-12 share a similar domain organization to each other and form a subgroup within the ADAMTS family. Emerging evidence suggests that ADAMTS-7 and ADAMTS-12 may play an important role in the development and pathogenesis of various kinds of diseases. In this review, we summarize what is currently known about the roles of these two metalloproteinases, with a special focus on their involvement in chondrogenesis, endochondral ossification, and the pathogenesis of arthritis, atherosclerosis, and cancer. The future study of ADAMTS-7 and ADAMTS-12, as well as the molecules with which they interact, will help us to better understand a variety of human diseases from both a biological and therapeutic standpoint.

ADAMTS-7, a direct target of PTHrP, adversely regulates endochondral bone growth by associating with and inactivating GEP growth factor

ADAMTS-7, a metalloproteinase that belongs to ADAMTS family, is important for the degradation of cartilage extracellular matrix proteins in arthritis. Herein we report that ADAMTS-7 is upregulated during chondrocyte differentiation and demonstrates the temporal and spatial expression pattern during skeletal development. ADAMTS-7 potently inhibits chondrocyte differentiation and endochondral bone formation, and this inhibition depends on its proteolytic activity. The cysteine-rich domain of ADAMTS-7 is required for its interaction with the extracellular matrix, and the C-terminal four-thrombospondin motifs are necessary for its full proteolytic activity and inhibition of chondrocyte differentiation. ADAMTS-7 is an important target of canonical PTHrP signaling, since (i) PTHrP induces ADAMTS-7, (ii) ADAMTS-7 is downregulated in PTHrP null mutant (PTHrP-/-) growth plate chondrocytes, and (iii) blockage of ADAMTS-7 almost abolishes PTHrP-mediated inhibition of chondrocyte hypertrophy and endochondral bone growth. ADAMTS-7 associates with granulin-epithelin precursor (GEP), an autocrine growth factor that has been implicated in tissue regeneration, tumorigenesis, and inflammation. In addition, ADAMTS-7 acts as a new GEP convertase and neutralizes GEP-stimulated endochondral bone formation. Collectively, these findings demonstrate that ADAMTS-7, a direct target of PTHrP signaling, negatively regulates endochondral bone formation by associating with and inactivating GEP chondrogenic growth factor.

Proepithelin is an autocrine growth factor for bladder cancer

The growth factor proepithelin functions as an important regulator of proliferation and motility. Proepithelin is overexpressed in a great variety of cancer cell lines and clinical specimens of breast, ovarian and renal cancer, as well as glioblastomas. Using recombinant proepithelin on 5637 transitional cell carcinoma-derived cells, we have shown previously that proepithelin plays a critical role in bladder cancer by promoting motility of bladder cancer cells. In this study, we used the ONCOMINE database and gene microarray analysis tool to analyze proepithelin expression in several bladder cancer microarray studies. We found a statistically significant increase in proepithelin messenger RNA expression in bladder cancers vis-à-vis non-neoplastic tissues, and this was associated with pathologic and prognostic parameters. Targeted downregulation of proepithelin in T24 transitional carcinoma cells with small hairpin RNA inhibited both Akt and mitogen-activated protein kinase pathways, severely reduced the ability of T24 cells to proliferate in the absence of serum and inhibited migration, invasion and wound healing. In support of these in vitro results, we discovered that proepithelin expression was significantly upregulated in invasive bladder cancer tissues compared with normal urothelium. In addition, proepithelin was secreted in the urine, where it was detectable by immunoblotting and enzyme-linked immunosorbent assay. Collectively, these results support the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and progression of bladder cancer and suggest that proepithelin may prove a novel biomarker for the diagnosis and prognosis of bladder neoplasms.

The role of ADAMTS-7 and ADAMTS-12 in the pathogenesis of arthritis

Loss of articular cartilage caused by extracellular matrix breakdown is the hallmark of arthritis. Degradative fragments of cartilage oligomeric matrix protein (COMP) have been observed in arthritic patients. ADAMTS-7 and ADAMTS-12, two members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, have been associated with COMP degradation in vitro, and are significantly overexpressed in the cartilage and synovium of patients with rheumatoid arthritis. Recent studies have demonstrated the importance of COMP degradation by ADAMTS-7 and ADAMTS-12. Specifically, the size of COMP fragments generated by ADAMTS-7 or ADAMTS-12 is similar to that of COMP-degradative fragments seen in arthritic patients. In addition, antibodies against ADAMTS-7 or ADAMTS-12 dramatically inhibit tumor necrosis factor-induced and interleukin-1beta-induced COMP degradation in cartilage explants. Furthermore, suppression of ADAMTS-7 or ADAMTS-12 expression using the small interfering RNA silencing approach in human chondrocytes markedly prevents COMP degradation. COMP degradation mediated by ADAMTS-7 and ADAMTS-12 is inhibited by alpha(2)-macroglobulin. More significantly, granulin-epithelin precursor, a newly characterized chondrogenic growth factor, disturbs the interaction between COMP and ADAMTS-7 and ADAMTS-12, preventing COMP degradation by these enzymes. This Review summarizes the evidence demonstrating that ADAMTS-7 and ADAMTS-12 are newly identified enzymes responsible for COMP degradation in arthritis, and that alpha(2)-macroglobulin and granulin-epithelin precursor represent their endogenous inhibitors.

Proepithelin regulates prostate cancer cell biology by promoting cell growth, migration, and anchorage-independent growth

The growth factor proepithelin has recently emerged as an important regulator of transformation in several physiological and pathological systems. In this study, we determined the biological roles of proepithelin in prostate cancer cells using purified human recombinant proepithelin as well as proepithelin-depletion strategies. Proepithelin promoted the migration of androgen-dependent and -independent human prostate cancer cells; androgen-independent DU145 cells were the more responsive. In these cells, proepithelin additionally stimulated wound closure, invasion, and promotion of cell growth in vitro. These effects required the activation of both the Akt and mitogen-activated protein kinase pathways. We have analyzed proepithelin expression levels in different available prostate cancer microarray studies using the Oncomine database and found a statistically significant increase in proepithelin mRNA expression levels in prostate cancers compared with nonneoplastic controls. Notably, depletion of endogenous proepithelin by siRNA and antisense strategies impaired the ability of DU145 cells to grow and migrate after serum withdrawal and inhibited anchorage-independent growth. Our results provide the first evidence for a role of proepithelin in stimulating the migration, invasion, proliferation, and anchorage-independent growth of prostate cancer cells. This study supports the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and initial progression of prostate cancer. Furthermore, proepithelin may prove to be a useful clinical marker for the diagnosis of prostate tumors.

Overexpression of protease inhibitor-dead secretory leukocyte protease inhibitor causes more aggressive ovarian cancer in vitro and in vivo

The alarm anti-protease secretory leukocyte protease inhibitor (SLPI) is frequently overexpressed in ovarian cancer cells and has been proposed for inclusion in biomarker panels but function remains unclear. We hypothesized that SLPI overexpression promotes ovarian cancer growth and survival. Low SLPI-expressing Hey-A8 ovarian cancer cells were engineered to produce functional (WT) or protease inhibitor-null (PI-) mutant SLPI; lack of PI activity was confirmed by enzymatic assay. WT/SLPI and PI- mutants stimulated significant proliferation and survival of Hey-A8 ovarian cancer cells under basal culture conditions (P < or = 0.02), in soft agar colony number and size (P < or = 0.05), and in anoikis resistance (P < or = 0.005). SLPI protected the ovarian cancer survival factor, progranulin (PRGN), and HEY-A8 cells from degradation and apoptosis due to neutrophil elastase. PI-/SLPI cells had greater protective activity than WT/SLPI cells. HEY-A8 murine xenografts revealed enhanced solid tumor formation, dissemination, and invasion in WT/SLPI and PI-/SLPI mutants. Increased proliferation was demonstrated by Ki-67 staining (P < or = 0.02). Increased secreted PRGN was seen in culture and was also observed by immunohistochemistry in the SLPI transfectant xenografts. This study describes a PI-independent function for SLPI in ovarian cancer growth and dissemination.

A snapshot of microarray-generated gene expression signatures associated with ovarian carcinoma

It was hypothesized that analysis of global gene expression in ovarian carcinoma can identify dysregulated genes that can serve as molecular markers and provide further insight into carcinogenesis and provide the basis for development of new diagnostic tools as well as new targeted therapy protocols. By applying bioinformatics tools for screening of biomedical databases, a gene expression profile databank, specific for ovarian carcinoma, was constructed with utilizable data sets published in 28 studies that applied different array technology platforms. The data sets were divided into four compartments: (i) genes associated with carcinogenesis: in 14 studies, 1881 genes were extracted, 75 genes were identified in more than one study, and only 4 genes (PRKCBP1, SPON1, TACSTD1, and PTPRM) were identified in three studies. (ii) Genes associated with histologic subtypes: in four studies, 463 genes could be identified, but none of them was identified in more than a single study. (iii) Genes associated with therapy response: in seven studies, 606 genes were identified from which 38 were differentially regulated in at least two studies, 3 genes (TMSB4X, GRN, and TJP1) in three studies, and 1 gene (IFITM1) in four studies. (iv) Genes associated with prognosis and progression: 254 genes were found in seven studies. From these genes, merely three were identified in at least two different studies. This snapshot of available gene expression data not only provides independently described potential diagnostic and therapeutic targets for ovarian carcinoma but also emphasizes the drawbacks of the current state of global gene expression analyses in ovarian cancer.

Different clinical roles for p21-activated kinase-1 in primary and recurrent ovarian carcinoma

We recently found amplification of chromosome 11q13.5 in high-grade ovarian serous carcinoma. In the present study, we analyzed the protein expression and clinical significance of p21-activated kinase-1, one of the genes amplified at this site. Formalin-fixed paraffin-embedded sections from 186 effusions (152 peritoneal, 34 pleural) were immunostained. p21-Activated kinase-1 expression in tumor cells was analyzed for possible association with clinicopathologic parameters and survival. The association between protein expression of p21-activated kinase-1 and Rsf-1, a chromatin remodeling protein whose gene colocalizes with p21-activated kinase-1, was additionally studied. p21-Activated kinase-1 protein expression was found in carcinoma cells in 158 (85%) of 186 effusions. Of these, 62 (39%) stained weakly and 96 (61%) strongly. p21-Activated kinase-1 was coexpressed with Rsf-1 (P = .006). Specimens from patients diagnosed with International Federation of Gynecology and Obstetrics stage IV disease had higher staining intensity compared with stage III tumors (P = .014). Univariate survival analysis for patients with primary diagnosis prechemotherapy effusions demonstrated a significant association between higher p21-activated kinase-1 staining extent and longer overall survival (P = .024). In addition, higher staining extent (P = .015) and intensity (P = .013) correlated with better progression-free survival. In contrast, higher p21-activated kinase-1 staining extent correlated with poor overall survival in disease recurrence postchemotherapy effusions (P = .044). In Cox analysis, higher p21-activated kinase-1 staining extent independently correlated with longer progression-free survival (P = .016) and shorter overall survival (.049) in primary diagnosis and disease recurrence effusions, respectively. p21-Activated kinase-1 is frequently expressed in ovarian carcinoma cells in effusions and is associated with opposite prognostic role in primary and recurrent disease. This suggests altered cellular function for this kinase along disease progression, possibly chemotherapy mediated.

Structure dissection of human progranulin identifies well-folded granulin/epithelin modules with unique functional activities

Progranulin is a secreted protein with important functions in several physiological and pathological processes, such as embryonic development, host defense, and wound repair. Autosomal dominant mutations in the progranulin gene cause frontotemporal dementia, while overexpression of progranulin promotes the invasive progression of a range of tumors, including those of the breast and the brain. Structurally, progranulin consists of seven-and-a-half tandem repeats of the granulin/epithelin module (GEM), several of which have been isolated as discrete 6-kDa GEM peptides. We have expressed all seven human GEMs using recombinant DNA in Escherichia coli. High-resolution NMR showed that only the three GEMs, hGrnA, hGrnC, and hGrnF, contain relatively well-defined three-dimensional structures in solution, while others are mainly mixtures of poorly structured disulfide isomers. The three-dimensional structures of hGrnA, hGrnC, and hGrnF contain a stable stack of two beta-hairpins in their N-terminal subdomains, but showed a more flexible C-terminal subdomain. Interestingly, of the well-structured GEMs, hGrnA demonstrated potent growth inhibition of a breast cancer cell line, while hGrnF was stimulatory. Poorly folded peptides were either weakly inhibitory or without activity. The functionally active and structurally well-characterized human hGrnA offers a unique opportunity for detailed structure-function studies of these important GEM proteins as novel members of mammalian growth factors.

Progranulin: normal function and role in neurodegeneration

Progranulin (PGRN) is a multifunctional protein that has attracted significant attention in the neuroscience community following the recent discovery of PGRN mutations in some cases of frontotemporal dementia. Most of the pathogenic mutations result in null alleles, and it is thought that frontotemporal dementia in these families results from PGRN haploinsufficiency. The neuropathology associated with PGRN mutations is characterized by the presence of tau-negative, ubiquitin-immunoreactive neuronal inclusions (frontotemporal lobar degeneration with ubiquitinated inclusions) that are also positive for the transactivation response DNA binding protein with M(r) 43 kD. The clinical phenotype includes behavioral abnormalities, language disorders and parkinsonism but not motor neuron disease. There is significant clinical variation between families with different PGRN mutations and among members of individual families. The normal function of PGRN is complex, with the full-length form of the protein having trophic and anti-inflammatory activity, whereas proteolytic cleavage generates granulin peptides that promote inflammatory activity. In the periphery, PGRN functions in wound healing responses and modulates inflammatory events. In the CNS, PGRN is expressed by neurons and microglia; consequently, reduced levels of PGRN could affect both neuronal survival and CNS inflammatory processes. In this review, we discuss current knowledge of the molecular genetics, neuropathology, clinical phenotype and functional aspects of PGRN in the context of neurodegenerative disease.

Progranulin is a stress-response factor in fibroblasts subjected to hypoxia and acidosis

The growth factor progranulin (granulin-epithelin precursor, PC-derived growth factor or acrogranin) regulates proliferation and migration and is implicated in cancer, development, wound repair and neurodegenerative diseases. Under most conditions fibroblasts do not express progranulin in vivo, however its expression is activated following wounding. We hypothesised that progranulin is part of a fibroblast stress response. Fibroblasts in culture were exposed to two physiologically and clinically relevant microenvironmental stresses; hypoxia (1% oxygen) and acidosis, both of which increase progranulin expression. The greatest increases occurred when hypoxia and acidosis were combined. Increased progranulin expression is not a direct response to apoptosis since it occurred under conditions of pH and hypoxia under which cell viability remained high. Low concentrations of progranulin (2 nM) protected fibroblasts from apoptosis induced by extreme acidosis (pH 5.0 and 4.0). We propose that progranulin is part of a fibroblast stress response and is cytoprotective to acidotic stress.

Expression and clinical role of the bric-a-brac tramtrack broad complex/poxvirus and zinc protein NAC-1 in ovarian carcinoma effusions

We recently identified NAC-1, member of the bric-a-brac tramtrack broad complex/poxvirus and zinc domain family, as an overexpressed gene in ovarian serous carcinoma and found more frequent NAC-1 protein expression in recurrent compared to primary tumors. In the present study, we assessed the clinical significance of NAC-1 expression in ovarian carcinoma effusions. Formalin-fixed, paraffin-embedded sections from 176 effusions (137 peritoneal, 39 pleural) and 197 corresponding solid tumors (69 primary tumors, 128 solid metastases) were analyzed for NAC-1 expression using immunohistochemistry. Staining intensity and extent results were analyzed for possible association with clinicopathologic parameters and survival. Nuclear NAC-1 immunoreactivity was found in carcinoma cells in 98% of (173/176) effusions, 94% (65/69) of primary tumors, and 95% (121/128) of metastases. Staining intensity and extent were significantly higher in effusions compared with matched solid tumors (P = .002 for intensity, P = .003 for extent compared with primary tumors; P < .001 for both intensity and extent compared with metastases). Furthermore, NAC-1 expression intensity was significantly higher in specimens obtained after the administration of chemotherapy (P = .002) and correlated with shorter progression-free survival (PFS) in analysis of 62 patients with post-chemotherapy effusions (P = .039). International Federation of Gynecology and Obstetrics stage (IV versus III) was the only clinical parameter associated with PFS in this group (P = .004). In Cox analysis, only the International Federation of Gynecology and Obstetrics stage was an independent predictor of shorter PFS (P = .009). In conclusion, NAC-1 expression is higher in ovarian carcinoma cells in effusions compared with their solid tumor counterparts. NAC-1 is up-regulated in tumor cells after chemotherapy, suggesting a role for this protein in tumor progression and in the development of chemotherapy resistance in ovarian cancer.

Prosurvival function of the granulin-epithelin precursor is important in tumor progression and chemoresponse

The granulin-epithelin precursor (GEP/PCDGF), a 68-88 kDa secreted glycoprotein, has been shown to be an important growth and survival factor for ovarian cancer cells. Furthermore, GEP expression is a predictor of patient survival in metastatic ovarian cancer cells. Up to this point, however, the molecular mechanisms and clinical relevance of a GEP-mediated prosurvival phenotype remain poorly characterized. We hypothesize that the prosurvival function of GEP is important in ovarian cancer tumor progression and chemoresponse. To explore this hypothesis, we examined the effects of GEP overexpression on migration, invasion and cisplatin (CDDP) chemosensitivity in the ovarian cancer cell line A2780. Full length GEP transfectants demonstrated an increased capacity to migrate and invade their substratum when compared to empty vector controls. In addition, GEP overexpression was associated with CDDP chemoresistance. Finally, GEP overexpression increased tumor formation and protected cells from tumor regression in response to CDDP treatment in vivo. Taken together, these data support a role for GEP in tumor progression and development of drug resistance.

Cartilage oligomeric matrix protein associates with granulin-epithelin precursor (GEP) and potentiates GEP-stimulated chondrocyte proliferation

Mutations in human cartilage oligomeric matrix protein (COMP) have been linked to the development of pseudoachondroplasia and multiple epiphyseal dysplasia; however, the functions of both wild-type and mutant COMP in the skeletogenesis remain unknown. In an effort to define the biological functions of COMP, a functional genetic screen based on the yeast two-hybrid system was performed. This led to the identification of granulin-epithelin precursor (GEP), an autocrine growth factor, as a COMP-associated partner. COMP directly binds to GEP both in vitro and in vivo, as revealed by in vitro pull down and co-immunoprecipitation assays. GEP selectively interacts with the epidermal growth factor repeat domain of COMP but not with the other three functional domains of COMP. The granulin A repeat unit of GEP is required and sufficient for association with COMP. COMP co-localizes with GEP predominantly in the pericellular matrix of transfected rat chondrosarcoma cell and primary human chondrocytes. Staining of musculoskeletal tissues of day 19 mouse embryo with antibodies to GEP is restricted to chondrocytes in the lower proliferative and upper hypertrophic zones. Overexpression of GEP stimulates the proliferation of chondrocytes, and this stimulation is enhanced by COMP. In addition, COMP appears to be required for GEP-mediated chondrocyte proliferation, since chondrocyte proliferation induced by GEP is dramatically inhibited by an anti-COMP antibody. These findings provide the first evidence linking the association of COMP and GEP and identifying a previously unrecognized growth factor (i.e. GEP) in cartilage.

Heparanase expression correlates with poor survival in metastatic ovarian carcinoma

OBJECTIVE

To analyze the expression of Heparanase, an enzyme involved in cancer metastasis and angiogenesis, in ovarian and breast carcinoma cells in effusions.

METHODS

Heparanase protein expression was analyzed in malignant effusions from ovarian (=200) and breast (=41) carcinoma patients using immunocytochemistry. The levels of secreted heparanase were analyzed in 45 effusion supernatants using a newly established ELISA test. Heparanase expression levels were analyzed for clinical significance.

RESULTS

Heparanase was expressed at the cell membrane in 106/200 (53%) ovarian and 22/41 (54%) breast carcinomas. Cytoplasmic expression was found in 180/200 (90%) ovarian and 26/41 (63%) breast carcinomas. Reactive mesothelial cells showed frequent cytoplasmic, but not membrane expression. ELISA showed secreted heparanase in all 45 analyzed effusions. Higher levels were detected in peritoneal compared to pleural effusions (p=0.031). In univariate survival analysis of ovarian carcinoma patients with post-chemotherapy effusions, membrane expression in >5% of tumor cells correlated with shorter overall survival (OS, p=0.013). FIGO stage (p=0.03 for all patients, p=0.045 for those with post-chemotherapy specimens) and response to first-line chemotherapy (p<0.0001 for all patients, p=0.049 for those with post-chemotherapy specimens) were the clinical parameters related to OS. In Cox analysis of this subset of patients, heparanase expression (p=0.02) and response to chemotherapy (p=0.049) were independent predictors of poor OS. Heparanase expression did not correlate with survival in breast carcinoma.

CONCLUSIONS

Our data show that heparanase is frequently expressed in metastatic gynecologic adenocarcinomas, and that it is secreted into the effusion fluid in body cavities. The correlation between heparanase expression and poor survival in ovarian carcinoma suggests a role for this molecule in ovarian cancer metastasis and supports its role as a marker of aggressive clinical behavior at disease recurrence.

Expression of the chromatin remodeling factor Rsf-1 is upregulated in ovarian carcinoma effusions and predicts poor survival

OBJECTIVE

We recently identified Rsf-1, a chromatin remodeling gene, as a potential oncogene that is frequently amplified and overexpressed in ovarian serous carcinoma. However, its clinical role in ovarian cancer effusions is not clear. In the present study, we assessed the clinical significance of Rsf-1 overexpression in ovarian carcinoma effusions.

METHODS

Formalin-fixed paraffin-embedded sections from 168 effusions (134 peritoneal, 34 pleural) were analyzed for Rsf-1 expression using immunocytochemistry. Matched primary tumors (n=48) and solid metastases (n=73) from 48 patients were additionally studied. Rsf-1 expression in tumor cells in effusions was analyzed for possible association with clinicopathologic parameters and survival.

RESULTS

Rsf-1 protein expression was found in carcinoma cells in 157/168 (93%) effusions. Of these, 70 (45%) stained weakly and 87 (55%) strongly. Specimens from patients diagnosed with FIGO stage IV disease had higher staining score (extent x intensity) compared with stage III tumors (P=0.008). Rsf-1 expression level was significantly lower in primary tumors and solid metastases (P<0.001 for extent, intensity and score). Univariate survival analysis for 59 patients with post-chemotherapy recurrence effusions demonstrated a significant association between higher Rsf-1 staining and shorter overall survival (OS; P=0.009 for staining extent and intensity, P=0.02 for staining score). FIGO stage was the only clinical parameter associated with OS in this group (P=0.032). In Cox analysis, Rsf-1 expression (P=0.022 for staining extent and intensity, P=0.045 for staining score) and FIGO stage (P=0.035) were independent predictors of shorter survival.

CONCLUSIONS

Rsf-1 is frequently expressed and upregulated in ovarian carcinoma cells in effusions and is a novel prognostic marker for patients with post-chemotherapy recurrent disease. The above findings support a role of Rsf-1 in mediating disease progression and aggressive clinical behavior in this subset of ovarian carcinoma patients.

Proepithelin promotes migration and invasion of 5637 bladder cancer cells through the activation of ERK1/2 and the formation of a paxillin/FAK/ERK complex

The growth factor proepithelin (also known as progranulin, acrogranin, PC-derived growth factor, or granulin-epithelin precursor) is a secreted glycoprotein that functions as an important regulator of cell growth, migration, and transformation. Proepithelin is overexpressed in a great variety of cancer cell lines and clinical specimens of breast, ovarian, and renal cancer as well as glioblastomas. In this study, we have investigated the effects of proepithelin on bladder cancer cells using human recombinant proepithelin purified to homogeneity from 293-EBNA cells. Although proepithelin did not appreciably affect cell growth, it did promote migration of 5637 bladder cancer cells and stimulate in vitro wound closure and invasion. These effects required the activation of the mitogen-activated protein kinase pathway and paxillin, which upon proepithelin stimulation formed a complex with focal adhesion kinase and active extracellular signal-regulated kinase. Our results provide the first evidence for a role of proepithelin in stimulating migration and invasion of bladder cancer cells, and support the hypothesis that this growth factor may play a critical role in the establishment of the invasive phenotype.

Regulation of progranulin expression in myeloid cells

Progranulin (pgrn; granulin-epithelin precursor, PC-cell-derived growth factor, or acrogranin) is a multifunctional secreted glycoprotein implicated in tumorigenesis, development, inflammation, and repair. It is highly expressed in macrophage and monocyte-derived dendritic cells. Here we investigate its regulation in myeloid cells. All-trans retinoic acid (ATRA) increased pgrn mRNA levels in myelomonocytic cells (CD34(+) progenitors; monoblastic U-937; monocytic THP-1; progranulocytic HL-60; macrophage RAW 264.7) but not in nonmyeloid cells tested. Interleukin-4 impaired basal expression of pgrn in U-937. Differentiation agents DMSO, and, in U-937 only, phorbol ester [phorbol 12-myristate,13-acetate (PMA)] elevated pgrn mRNA expression late in differentiation, suggestive of roles for pgrn in more mature terminally differentiated granulocyte/monocytes rather than during growth or differentiation. The response of pgrn mRNA to ATRA differs in U-937 and HL-60 lineages. In U-937, ATRA and chemical differentiation agents greatly increased pgrn mRNA stability, whereas, in HL-60, ATRA accelerated pgrn mRNA turnover. The initial upregulation of pgrn mRNA after stimulation with ATRA was independent of de novo protein synthesis in U-937 but not HL-60. Chemical blockade of nuclear factor-kappaB (NF-kappaB) activation impaired ATRA-stimulated pgrn expression in HL-60 but not U-937, whereas in U-937 it blocked PMA-induced pgrn mRNA expression, suggestive of cell-specific roles for NF-kappaB in determining pgrn mRNA levels. We propose that: 1) ATRA regulates pgrn mRNA levels in myelomonocytic cells; 2) ATRA acts in a cell-specific manner involving the differential control of mRNA stability and differential requirement for NF-kappaB signaling; and 3) elevated pgrn mRNA expression is characteristic of more mature cells and does not stimulate differentiation.

The granulin-epithelin precursor is a steroid-regulated growth factor in endometrial cancer

OBJECTIVES

The majority of endometrial cancers arise as a result of estrogen stimulation, the molecular targets of which remain incompletely defined. We hypothesize that the granulin-epithelin precursor (GEP) may be one such target. In this study, we examined the frequency of GEP and estrogen receptor (ER) co-expression in human endometrial cancers. Once we established the co-expression of GEP with the estrogen receptor we examined the potential estrogen regulation of GEP expression, as well as the functional significance of GEP expression in vitro.

METHODS

Double immunofluorescence and confocal microscopy were used to compare GEP and ER expression among 41 endometrial cancers. The effects of estradiol and tamoxifen treatment on GEP expression in two endometrial cancer cell lines, KLE and HEC-1-A, were assessed through reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. The antiproliferative effect of GEP silencing by short hairpin (sh)RNA, was evaluated in HEC-1-A cells using an MTT assay.

RESULTS

GEP co-expression with ER was observed in 63% of the cancers examined. A two- to fivefold increase in GEP expression with estradiol and/or tamoxifen treatment was observed in KLE cells. Silencing of GEP in HEC-1-A cells using shRNA resulted in a decrease in proliferation among transfected cells.

CONCLUSIONS

Co-expression of GEP and ER in endometrial cancer cells, and the regulation of GEP by estrogen, suggests a role for GEP in steroid-mediated endometrial cancer cell growth. Further characterization of GEP as a steroid-mediated growth factor in these cells may broaden our understanding of endometrial cancer biology and also provide guidance in the development of novel therapeutic targets.

A Novel Hematopoietic Granulin Induces Proliferation of Goldfish (Carassius auratus L.) Macrophages

Granulins are a group of highly conserved growth factors that have been described from a variety of organisms spanning the metazoa. In this study, goldfish granulin was one of the most commonly identified transcripts in the differential cross-screening of macrophage cDNA libraries and was preferentially expressed in proliferating macrophages. Unlike mammalian granulins, which possess 7.5 repeats of a characteristic signature of 12 cysteine residues, the goldfish granulin encoded a putative peptide possessing only 1.5 cysteine repeats. Northern blot and real-time PCR analyses indicated that goldfish granulin was expressed only in the hematopoietic tissues of the goldfish, specifically the kidney and spleen, and in activated peripheral blood mononuclear cells. We expressed granulin using a prokaryotic expression system and produced an affinity-purified rabbit anti-goldfish granulin IgG. Recombinant goldfish granulin induced a dose-dependent proliferative response of goldfish macrophages that was inversely related to the myeloid differentiation stage of the cells studied. The highest proliferative response was observed in macrophage progenitor cells and monocytes. This proliferative response of macrophages was abrogated by the addition of anti-granulin IgG. These results indicate that goldfish granulin is a growth factor that positively modulates cell proliferation at distinct junctures of macrophage differentiation.

Oncogenic Property of Acrogranin in Human Uterine Leiomyosarcoma: Direct Evidence of Genetic Contribution inIn vivoTumorigenesis

To identify potential oncogenes that contribute to the development of uterine leiomyosarcoma, we conducted a cDNA microarray analysis between normal uterine smooth muscle and uterine leiomyosarcoma. We found that acrogranin (also named PCDGF or progranulin) is overexpressed in uterine leiomyosarcoma. With immunohistochemical staining of 12 leiomyosarcoma cases, we verified acrogranin expression in tumor cells. Furthermore, the intensity of acrogranin expression correlated with high histologic grade and poor prognosis. To directly analyze the oncogenic properties of acrogranin, we established an immortalized uterine smooth muscle cell line by transfection of human telomerase reverse transcriptase into primary culture. This cell line retained the original characteristics of uterine smooth muscle cells, including spindle-shaped extension as well as expression of vimentin, estrogen receptor alpha, progesterone receptor, and alpha smooth muscle actin. Transfection of acrogranin into the immortalized uterine smooth muscle cells resulted in colony formation in soft agar, but the diameter of the colonies did not exceed 100 mum. Transfection of both acrogranin and SV40 early region (SV40ER) into the immortalized uterine smooth muscle cells resulted in an increased number of colonies and increased colony size in soft agar versus transfection of SV40ER alone. We show that only immortalized uterine smooth muscle cells expressing both acrogranin and SV40ER are capable of tumor formation in nude mice. Thus, acrogranin is overexpressed in uterine leiomyosarcoma cells, particularly in high-grade cases, and forced expression of acrogranin in immortalized uterine smooth muscle cells contributes to malignant transformation, which suggest that acrogranin plays an important role in the pathogenesis of uterine leiomyosarcoma.

Malignant effusions are sources of fibronectin and other promigratory and proinvasive components

Metastatic dissemination is the primary cause of death in ovarian cancer (OvCa) patients, and dissemination to pleural and peritoneal effusions is a common clinical event. Effusion samples were collected from 15 OvCa patients. Twenty-six samples were collected prospectively, two were archival, and eight were taken from patients with other malignancies. Twenty-nine samples were from malignant ascites, and seven specimens were pleural fluids. In addition, six ascites and two pleural fluids from noncancer patients were studied as effusion controls. Effusion supernatants were tested for migration-stimulation activity, using A2058 human melanoma cells as the index responder cell. Malignant samples induced a 400-1200% increase in migration. Sixty percent of the migration was inhibited by incubation of the malignant fluid with antifibronectin (FN) antibody, in contrast to 75% inhibition of control fluid-stimulated migration (P = 0.017). Gelatin zymography and Western blot analyses showed that latent and activated MMP-2 and MMP-9 collagenases, and tissue inhibitor of metalloproteinase-2 (TIMP-2) were present in all malignant fluids. Serial samples were taken from several patients, and a trend for correlation between MMPs and clinical behavior of the tumors was shown. Free TIMP-2 correlated with CA-125 levels in two patients for whom serial samples were available. The demonstration of promigratory and proinvasive activity in malignant effusions is consistent with their association with other metastatic disease in OvCa patients and their function as a haven for metastatic cells.

Lysophosphatidic acid and endothelin-induced proliferation of ovarian cancer cell lines is mitigated by neutralization of granulin-epithelin precursor (GEP), a prosurvival factor for ovarian cancer

Granulin-epithelin precursor (GEP/progranulin) is an autocrine growth factor for ovarian cancer. We examined the production and function of GEP and report that: (1) GEP production is regulated by endothelin (ET-1), lysophosphatidic acid (LPA), and cAMP; (2) cAMP signals GEP production through exchange protein activated by cAMP (EPAC); (3) ET-1 and cAMP/EPAC induce GEP through ERK1/2; and (4) neutralization of GEP results in apoptosis. Exposure of HEY-A8 and OVCAR3 ovarian cancer cells to LPA and ET-1 yielded GEP production and secretion in a dose- and time-dependent fashion; neither stimulated significant concentrations of cAMP directly. Stimulation of cAMP production with pertussis and cholera toxin, or forskolin induced GEP in a PKA-independent fashion. EPAC, an intracellular cAMP receptor, is activated specifically by the cAMP analog, 8-CPT-2'-O-Me-cAMP (8-CPT); 8-CPT treatment stimulated GEP production and secretion. The MEK inhibitor, U0126, abrogated GEP production in response to ET-1 and 8-CPT, confirming involvement of MAPK. A partial inhibition of basal and stimulated GEP production was observed when cells were treated with a internal calcium chelator, BAPTA. Neutralizing anti-GEP antibody reversed basal as well as LPA, ET-1 and 8-CPT-induced ovarian cancer cell growth and induced apoptosis as demonstrated by caspase-3 and PARP cleavage, DNA fragmentation, and nuclear condensation. These results indicate that GEP is a growth and survival factor for ovarian cancer, induced by LPA and ET-1 and cAMP/EPAC through ERK1/2.

Snail, Slug, and Smad-interacting protein 1 as novel parameters of disease aggressiveness in metastatic ovarian and breast carcinoma

BACKGROUND

It was demonstrated previously that the Snail family of transcription factors and Smad-interacting protein 1 (Sip1) regulate E-cadherin and matrix metalloproteinase 2 (MMP-2) expression, cellular morphology, and invasion in carcinoma. For the current study, the authors analyzed the relation between the expression of Snail, Slug, and Sip1; the expression of MMP-2 and E-cadherin; and clinical parameters in patients with metastatic ovarian and breast carcinoma.

METHODS

One hundred one fresh-frozen, malignant effusions from patients who were diagnosed with gynecologic carcinomas (78 ovarian carcinomas and 23 breast carcinomas) were studied for mRNA expression of Snail, Slug, Sip1, MMP-2, and E-cadherin using reverse transcriptase-polymerase chain reaction analysis. Snail mRNA and E-cadherin protein expression levels also were studied in ovarian carcinoma effusions using in situ hybridization and immunocytochemistry. The results were analyzed for possible correlation with clinicopathologic parameters in both tumor types.

RESULTS

E-cadherin mRNA expression was lower in breast carcinoma (P = 0.001), whereas Snail expression was higher (P = 0.003). The Snail/E-cadherin ratio (P < 0.001) and the Sip1/E-cadherin ratio (P = 0.002) were higher in breast carcinomas. Sip1 mRNA expression (P < 0.001) and Slug mRNA expression (P < 0.001) were correlated with the expression of MMP-2 in ovarian carcinomas. The Sip1/E-cadherin ratio was higher in primary ovarian carcinomas at the time of diagnosis compared with postchemotherapy ovarian carcinoma effusions (P = 0.003), higher in Stage IV tumors compared with Stage III tumors (P = 0.049), and higher in pleural effusions compared with peritoneal effusions (P = 0.044). In a univariate survival analysis of patients with ovarian carcinoma, a high Sip1/E-cadherin ratio predicted poor overall survival (P = 0.018). High E-cadherin mRNA expression predicted better disease-free survival (P = 0.023), with a similar trend for a low Slug/E-cadherin ratio (P = 0.07). High Snail mRNA expression predicted shorter effusion-free survival (P = 0.008), disease-free survival (P = 0.03), and overall survival (P = 0.008) in patients with breast carcinoma.

CONCLUSIONS

Transcription factors that regulate E-cadherin were expressed differentially in metastatic ovarian and breast carcinoma. Snail may predict a poor outcome in patients who have breast carcinoma metastatic to effusions. E-cadherin expression generally was conserved in effusions from patients with ovarian carcinoma, but the subset of patients with postulated Sip1-induced repression of this adhesion molecule had a significantly worse outcome. This finding was in agreement with the stronger suppression of E-cadherin by Snail and Sip1 in breast carcinoma effusions, a clinical condition associated with extremely poor survival.

Altered expression of metastasis-associated and regulatory molecules in effusions from breast cancer patients: a novel model for tumor progression

PURPOSE

The aim of this study was to characterize phenotypic alterations along the progression of breast carcinoma from primary tumor to pleural effusion through analysis of the expression of proteases, laminin receptors (LRs), and transcription factors involved in invasion and metastasis.

EXPERIMENTAL DESIGN

The material studied consisted of 60 malignant pleural effusions from breast cancer patients and 68 corresponding solid tumors (37 primary and 31 metastatic tumors). Expression of matrix metalloproteinases [MMPs (MMP-1, MMP-2, MMP-9, and MMP-14)], the MMP inhibitor tissue inhibitor of metalloproteinase-2, the MMP inducer EMMPRIN, the 67-kDa LR, the alpha6 integrin subunit, and the transcription factors AP-2, Ets-1, and PEA3 was studied using immunohistochemistry, mRNA in situ hybridization, reverse transcription-polymerase chain reaction, zymography, and flow cytometry. Hormone receptor (estrogen receptor and progesterone receptor) status and c-erbB-2 status were also studied.

RESULTS

Significantly reduced estrogen receptor (P < 0.001) and progesterone receptor (P = 0.001) expression was seen in effusions compared with primary tumors, with opposite findings for c-erbB-2 (P = 0.003). Tumor cell MMP-2 protein expression in effusions was higher than that in primary tumors (P < 0.001) and lymph node metastases (P = 0.01). In situ hybridization demonstrated higher MMP-2 (P = 0.007), PEA3 (P = 0.038), and EMMPRIN (P = 0.026) mRNA expression in effusions. The time to progression from primary tumor to effusion was significantly shorter for patients whose primary tumors expressed MMP-1 (P = 0.016) and who expressed the 67-kDa LR protein in primary tumor (P = 0.007) and effusion (P = 0.015).

CONCLUSIONS

Our data provide documented evidence of molecular events that occur during the progression of breast carcinoma from primary tumor to effusion. The coordinated up-regulation of MMP-2 and Ets transcription factors in carcinoma cells in effusions is in full agreement with our previous reports linking these factors to poor prognosis in ovarian cancer. The rapid progression to effusion in cases showing MMP-1 and 67-kDa LR expression in primary tumor cells links aggressive clinical behavior with expression of metastasis-associated molecules in this setting.

Granulin and granulin repeats interact with the Tat.P-TEFb complex and inhibit Tat transactivation

The cellular positive transcription elongation factor b (P-TEFb), containing cyclin T1 and cyclin-dependent kinase 9 (CDK9), interacts with the human immunodeficiency virus, type 1 (HIV-1) regulatory protein Tat to enable viral transcription and replication. Cyclin T1 is an unusually long cyclin and is engaged by cellular regulatory proteins. Previous studies showed that the granulin/epithelin precursor (GEP) binds the histidine-rich region of cyclin T1 and inhibits P-TEFb function. GEP is composed of repeats that vary in sequence and properties. GEP also binds directly to Tat. Here we show that GEP and some of its constituent granulin repeats can inhibit HIV-1 transcription via Tat without directly binding to cyclin T1. The interactions of granulins with Tat and cyclin T1 differ with respect to their binding sites and divalent cation requirements, and we identified granulin repeats that bind differentially to Tat and cyclin T1. Granulins DE and E bind Tat but do not interact directly with cyclin T1. These granulins are present in complexes with Tat and P-TEFb in which Tat forms a bridge between the cellular proteins. Granulins DE and E repress transcription from the HIV-1 LTR and gene expression from the viral genome, raising the possibility of developing granulin-based inhibitors of viral infection.

Tumor microenvironment: What can effusions teach us?

Malignant effusions, which are composed of malignant pleural and peritoneal fluid, are an unusual manifestation of cancer and frequently portend a poor prognosis. Neoplastic cells that disseminate into cavities containing effusions are highly metastatic and possess a strong autonomous proliferative drive while concurrently being stimulatory of exudative effusions. Most effusions will respond to transient therapeutic intervention, including the obliteration of potential space via pleurodesis. Cure, however, is rare, thus making effusions a biologically, biochemically, and clinically important topic of study. The local microenvironment that supports malignant growth, invasion, and dissemination of the solid primary tumor into the vasculature is composed of activated stroma that includes scaffolding consisting of materials that promote the tumor function, and vascular structures to provide conduits for travel and nutrient delivery. Less is understood about the tumor-cell microenvironment in malignant effusions. The fluid nature of such a microenvironment when compared with the solid primary tumor may have significant implications for disease dissemination and progression. Dissecting the signaling activity and components of such microenvironments will improve our understanding and ultimately our ability to provide better patient care.

Malignant effusions: From diagnosis to biology

Serous effusions are a frequently encountered clinical manifestation of metastatic disease, with breast, ovarian, and lung carcinomas and malignant mesothelioma (MM) leading the list. Recently, extensive research has resulted in expansion of the antibody panel that is available for effusion diagnosis, thereby reducing the risk for error. Despite this progress, relatively little has been done in way of understanding the biology of cancer cells in effusions, especially those of nonovarian origin. The diagnosis of a malignant effusion signifies disease progression and is associated with a worse prognosis regardless of the tumor site of origin. However, survival is much more variable with ovarian cancer compared with other tumors. Furthermore, cancer cells of different origins differ considerably in their biology and have unique phenotypic and genotypic characteristics. This review summarizes the current knowledge in this field and presents a model for the study of tumor metastasis and disease progression, through large comparative studies of malignant cells in effusions, primary tumors, and solid metastases. The case also is made for potential applications of this rapidly evolving body of knowledge in the diagnosis, classification, and prediction of biological behavior of processes resulting in cryptic effusions at the clinical level.