Growth inhibition in clonal subpopulations of a human epithelioid sarcoma cell line by retinoic acid and tumour necrosis factor alpha

Epithelioid Sarcoma: Opportunities for Biology-Driven Targeted Therapy

Epithelioid sarcoma (ES) is a soft tissue sarcoma of children and young adults for which the preferred treatment for localized disease is wide surgical resection. Medical management is to a great extent undefined, and therefore for patients with regional and distal metastases, the development of targeted therapies is greatly desired. In this review, we will summarize clinically relevant biomarkers (e.g., SMARCB1, CA125, dysadherin, and others) with respect to targeted therapeutic opportunities. We will also examine the role of EGFR, mTOR, and polykinase inhibitors (e.g., sunitinib) in the management of local and disseminated disease. Toward building a consortium of pharmaceutical, academic, and non-profit collaborators, we will discuss the state of resources for investigating ES with respect to cell line resources, tissue banks, and registries so that a roadmap can be developed toward effective biology-driven therapies.

Infliximab Therapy in Patients with Chronic Sarcoidosis and Pulmonary Involvement

RATIONALE

Evidence suggests that tumor necrosis factor (TNF)-alpha plays an important role in the pathophysiology of sarcoidosis.

OBJECTIVES

To assess the efficacy of infliximab in sarcoidosis.

METHODS

A phase 2, multicenter, randomized, double-blind, placebo-controlled study was conducted in 138 patients with chronic pulmonary sarcoidosis. Patients were randomized to receive intravenous infusions of infliximab (3 or 5 mg/kg) or placebo at Weeks 0, 2, 6, 12, 18, and 24 and were followed through Week 52.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was the change from baseline to Week 24 in percent of predicted FVC. Major secondary efficacy parameters included Saint George's Respiratory Questionnaire, 6-min walk distance, Borg's CR10 dyspnea score, and the proportion of Lupus Pernio Physician's Global Assessment responders for patients with facial skin involvement. Patients in the combined infliximab groups (3 and 5 mg/kg) had a mean increase of 2.5% from baseline to Week 24 in the percent of predicted FVC, compared with no change in placebo-treated patients (p = 0.038). No significant differences between the treatment groups were observed for any of the major secondary endpoints at Week 24. Results of post hoc exploratory analyses suggested that patients with more severe disease tended to benefit more from infliximab treatment.

CONCLUSIONS

Infliximab therapy resulted in a statistically significant improvement in % predicted FVC at Week 24. The clinical importance of this finding is not clear. The results of this Phase 2 clinical study support further evaluation of anti-TNF-alpha therapy in severe, chronic, symptomatic sarcoidosis.

Rac affects invasion of human renal cell carcinomas by up-regulating tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 expression

Rho-like GTPases, including Cdc42, Rac1, and RhoA, regulate distinct actin cytoskeleton changes required for adhesion, migration, and invasion of cells. Tiam1 specifically activates Rac, and earlier studies have demonstrated that Tiam1-Rac signaling affects migration and invasion in a cell type- and cell substrate-specific manner. In the present study, we examined the role of Tiam1-Rac signaling in migration and invasion of human renal cell carcinomas. Stable overexpression of Tiam1 or constitutively active V12-Rac1 in a human renal cell carcinoma cell line (clearCa-28) strongly inhibited cell migration by promoting E-cadherin-mediated cell-cell adhesion. Blocking E-cadherin-mediated adhesion by E-cadherin-specific HAV peptides allowed cells to migrate, but was not sufficient to antagonize Tiam1- and V12-Rac1-induced inhibition of Matrigel invasion, suggesting that Rac may influence invasion also through other mechanisms. Indeed, Tiam1-mediated Rac activation induced transcriptional up-regulation of tissue inhibitor of metalloproteinases-1 (TIMP-1) and post-transcriptional up-regulation of TIMP-2, whereas secretion and activity levels of their counterparts, matrix metalloproteinase-9 and matrix metalloproteinase-2, respectively, were not affected. Application of recombinant TIMP-1 and TIMP-2 proteins significantly inhibited invasion of mock-transfected clearCa-28 cells, supporting a role of TIMPs in Rac-mediated inhibition of invasion. To our knowledge, this is the first evidence that increased Rac signaling may inhibit invasion of epithelial tumor cells by up-regulation of TIMP-1 and TIMP-2.

Differentially expressed genes in association with in vitro invasiveness of human epithelioid sarcoma

AIMS

Differential display reverse transcription polymerase chain reaction (RT-PCR) was performed to identify genes associated with the invasive potential of human epithelioid sarcoma.

METHODS

Two different clonal subpopulations, GRU-1A and GRU-1B, derived from the same human epithelioid sarcoma cell line GRU-1 and known to differ greatly in their invasive potential were compared by means of mRNA fingerprinting.

RESULTS

Using a set of 10 arbitrary upstream primers and nine anchored oligo-dT primers, 22 candidate gene fragments were identified; differential expression was confirmed in four of these fragments by northern blot analysis. At the mRNA level, apoferritin light chain was predominantly expressed by the highly invasive cell line GRU-1A. In contrast, the mitochondrial gene M1, encoding cytochrome c oxidase I, and the TI-227H gene were expressed more strongly by the low invasive cell line GRU-1B. Furthermore, a novel gene fragment was identified and cloned that was preferentially expressed in the low invasive cell line GRU-1B, and therefore might have an inhibitory role in invasion. Consequently, this gene fragment was designated as expressed in low invasive sarcoma cells (ELISC-1).

CONCLUSIONS

A novel gene fragment (ELISC-1) and three known genes were identified as potential regulators of tumour invasiveness. Cloning of the entire sequence of ELISC-1 and subsequent investigations are required to establish its biological role.

Analysis of growth factor-dependent signalling in human epithelioid sarcoma cell lines. clues To the role of autocrine, juxtacrine and paracrine interactions in epithelioid sarcoma

Human epithelioid sarcoma (ES) is an extremely aggressive soft tissue tumour of unknown histogenesis. Although growth factor-dependent signalling cascades significantly affect the biological behaviour of malignant tumours, little is known so far about their role in human ES. The present investigation, therefore, analyses the coexpression and function of different growth factors and their receptors in the human ES cell line GRU-1 and its clonal subpopulations (GRU-1A, GRU-1B and GRU-1C). As shown by Northern blot, flow cytometry, immunocytochemistry and MTT assay, all ES cell lines expressed transforming growth factor (TGF)-alpha and the epidermal growth factor receptor (EGF-R). Although no response to exogenous TGF-alpha was observed, antagonistic anti-EGF-R antibodies (at 20 microg/ml) induced significant (P<0.05) growth inhibition in all cell lines. All cell lines showed coexpression of platelet-derived growth factor (PDGF)-A and the corresponding receptors. Neutralisation of ES-derived PDGF by anti-hPDGF antibodies resulted in significant (P<0.05) growth inhibition of all clonal subpopulations. Although all cell lines expressed TGF-beta(1) as well as TGF-beta type I and type II receptors (TGF-BI-R and TGF-BII-R), growth inhibition (P<0.05) by exogenous TGF-beta(1) was achieved in the clonal subpopulations only and not in the parental cell line. No ES cell line expressed acidic fibroblast growth factor (FGF) but stimulation of FGF type 3 and type 4 receptors (FGF-3R and FGF-4R) by exogenous acidic FGF (aFGF) resulted in a marked (P<0.05) acceleration of proliferation in all cell lines. In conclusion, our investigation suggests an intricate network of autocrine, juxtacrine and paracrine signalling between ES tumour cells and adjacent non-neoplastic stromal cells.

Growth inhibitory effects of paclitaxel on human epithelioid sarcoma in vitro: heterogeneity of response and the multidrug resistance phenotype

BACKGROUND

Epithelioid sarcoma is a highly malignant soft tissue tumor that is largely resistant to conventional chemotherapy and radiotherapy. Because paclitaxel has been proven to be effective in other human malignancies refractory to conventional chemotherapy, the authors analyzed the in vitro growth inhibitory effects of paclitaxel on the human epithelioid-sarcoma cell line GRU-1 and its clonal subpopulations GRU-1A, GRU-1B, and GRU-1C.

METHODS

Paclitaxel-induced morphologic alterations were visualized using light microscopy, immunofluorescence microscopy, and transmission electron microscopy. The antiproliferative effects of paclitaxel on the cell lines were determined by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium' bromide (MTT) assay. The extent of paclitaxel-induced apoptosis was determined by light microscopy. The expression and function of P-glycoprotein and the multidrug resistance-associated protein (MRP) were defined by reverse transcriptase-polymerase chain reaction and fluorescence-activated cell sorter analysis.

RESULTS

Paclitaxel-induced morphologic alterations such as micronucleus formation and microtubule bundles showed no significant differences between the parental cell line and its clonal subpopulations. A significant (P < 0.05) dose-dependent growth inhibition was observed in GRU-1 and its clonal subpopulations, with the IC(50) (concentration that inhibits 50%) values ranging from 0.04-0.49 microM in the different subpopulations. Paclitaxel-induced growth inhibition was accompanied by a slight increase in apoptosis. All cell lines showed an expression of and an effective function of P-glycoprotein and MRP.

CONCLUSIONS

The differential response of GRU-1 and its clonal subpopulations to paclitaxel could not be predicted by the expression and function of P-glycoprotein and MRP, suggesting that other drug resistance mechanisms might be relevant in the heterogenous response observed in the epithelioid sarcoma cell lines in the current study.

Inhibition of proliferation and induction of apoptosis in soft tissue sarcoma cells by interferon-alpha and retinoids

Uncontrolled proliferation and a defect of apoptosis constitute crucial elements in the development and progression of tumours. Among many other biological response modifiers known to influence these mechanisms, the efficacy of retinoids and interferons in the treatment of various malignant entities is currently matter of discussion. In the present study, we have investigated the effects of 9-cis-retinoic acid (9cRA), 13-cis-retinoic acid (13cRA), all-trans-retinoic acid (tRA) and interferon-alpha on proliferation and apoptosis of human soft tissue sarcoma (STS) cell lines HTB-82 (rhabdomyosarcoma), HTB-91 (fibrosarcoma), HTB-92 (liposarcoma), HTB-93 (synovial sarcoma) and HTB-94 (chondrosarcoma) in relation to p53 genotype as well as p53 expression. HTB-91, HTB-92 and HTB-94 STS cells exhibited mutant p53, whereas wild-type p53 was found in HTB-93 STS cells, and a normal p53 status in HTB-82 STS cells, carrying a silent point mutation only. Interferon-alpha, irrespective of p53 status, inhibited the proliferation of all five cell lines dose- and time-dependently. Similarly, 9cRA, 13cRA and tRA decreased the proliferation of HTB-82 and HTB-93 STS cells, whereas the proliferation of p53-mutated HTB-91, HTB-92 and HTB-94 STS cells remained unchanged. Furthermore, only 9cRA and tRA were capable of inducing apoptosis in HTB-82 and HTB-93 STS cells, whereas HTB-91, HTB-92 and HTB-94 STS cells did not undergo apoptosis under the influence of 9cRA or tRA. Retinoic acid receptor (RAR)-alpha and RAR-beta mRNA were not detectable by Northern blot analysis in the five STS cell lines, whereas mRNA for the universal retinoic acid receptor, RAR-gamma, was expressed in all STS cell lines indicating that retinoid resistance was not associated with a lack of RAR expression. Apoptosis was not induced by interferon-alpha or 13cRA in any of the five STS cell lines tested. Our results indicate that within the panel of tested STS cell lines, inhibition of proliferation and induction of apoptosis result from different mechanisms which differ in their dependence upon the presence of intact p53.

In vitro invasiveness of human epithelioid-sarcoma cell lines: association with cell motility and inverse correlation with the expression of tissue inhibitor of metalloproteinases

Epithelioid sarcoma (ES) is a very aggressive soft-tissue tumor in vivo, but no experimental data on its invasive and metastatic behavior have been reported. In the present study, 3 different clonal sub-populations (GRU-1A, GRU-1B and GRU-1C), derived from the same human ES cell line, GRU-1, were investigated for in vitro invasiveness in relation to migration, adhesion and the expression of different invasion- and metastasis-related genes. Tumor spheroids of GRU-1A were markedly more invasive in the chick-heart invasion assay (CHIA) than spheroids of GRU-1B and GRU-1C. These results were paralleled by a significantly higher cell motility of GRU-1A than GRU-1B and GRU-1C (p < 0.05) on distinct substrates, suggesting that the observed differences in invasion result at least in part from differences in motility. When invasion was assayed with suspended tumor cells in the Matrigel assay, differences between the 3 cell lines were much more pronounced than in the CHIA, where cell-cell contacts are established. These results indicate that interclonal differences in ES invasion result mainly from differences in motility, but also partly depend on differences in cell-cell adhesion. On the molecular level, low invasive potential was associated with over-expression of distinct tissue inhibitor of metalloproteinases (TIMPs) relative to matrix metalloproteinase-2 and -9. However, no association was found between invasion and the expression of CD44 splicing variants or nm23 isoforms. Our results suggest that differences in invasion between GRU-1A, GRU-1B and GRU-1C are caused mainly by interclonal differences in migration, and might result from differences in the expression of distinct TIMPs.

Effect of tumour necrosis factor-alpha on proliferation, activation and protein synthesis of rat hepatic stellate cells

BACKGROUND/AIMS

Hepatic stellate cells represent the principal matrix-synthesising cells of damaged liver and are targets of a number of cytokines currently under investigation. The study analyses the effects of tumour necrosis factor-alpha and interferon-gamma on proliferation, "activation" and protein synthesis of hepatic stellate cells.

METHODS

Primary cultures of hepatic stellate cells were exposed to tumour necrosis factor-alpha and interferon-gamma. Cell proliferation was studied by 3H-thymidine and bromo-deoxy-uridine incorporation. Protein synthesis was analysed using immunoprecipitation, Western- and Northern blotting techniques.

RESULTS

Proliferation of hepatic stellate cells was reduced by tumor necrosis factor-alpha and interferon-gamma, while "activation" of hepatic stellate cells as assessed by expression of smooth muscle alpha-actin and of TGF-beta/activin type I receptor was induced by tumour necrosis factor-alpha but downregulated by interferon-gamma. Tumour necrosis factor-alpha increased the synthesis of distinct extracellular matrix proteins, particularly of fibronectin and tenascin, but decreased collagen type III expression. In contrast, interferon-gamma reduced the synthesis of all connective tissue proteins tested. Among the protease inhibitors, interferon-gamma induced C1-esterase inhibitor synthesis, while tumour necrosis factor-alpha stimulated plasminogen activator inhibitor type 1 production.

CONCLUSIONS

Tumour necrosis factor-alpha and interferon-gamma decrease proliferation of hepatic stellate cells, while "activation" of hepatic stellate cells and synthesis of proteins involved in matrix metabolism are regulated in a differential, cytokine-specific manner, suggesting that both cytokines play an important role in liver repair.