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Synthesis of hyaluronan in oesophageal cancer cells is uncoupled from the prostaglandin-cAMP pathway.

ABSTRACT: BACKGROUND AND PURPOSE: Cyclooxygenase-2 (COX2) and hyaluronic acid (HA) are common in tumours and both independently promote tumour progression. Furthermore, COX2-dependent synthesis of prostaglandins (PGs) stimulates HA synthase-1 (HAS1) and HAS2 mRNA expression, together with HA synthesis via the cAMP/protein kinase A pathway in vascular smooth muscle cells. Therefore, the aim of the present study was to elucidate whether COX2-mediated PGs induce transcription of HAS isoforms in cancer cells as well. EXPERIMENTAL APPROACH: Human oesophageal squamous cell (OSC) carcinoma specimens were characterized with respect to HA, COX2 and CD44 expression by immunohistochemistry. OSC cell lines (OSC1, OSC2) and HeLa cell lines (D98, H21) were exposed to exogenous PG analoques (100 nmol.L(-1)), etoricoxib (10 micromol.L(-1)) and forskolin (10 micromol.L(-1)). Subsequently, cAMP levels, HA secretion and HAS isoform expression were determined by elisa and real-time RT-PCR (reverse transcriptase polymerase chain reaction) respectively. KEY RESULTS: COX2, HA and CD44 were detected immunohistochemically in >90% of human oesophageal tumour samples. Under basal conditions, OSC1 and OSC2 cells express HAS2 and HAS3, COX2 and Galpha(s)-coupled EP(2) and EP(4) PG receptors. Neither stimulation with the PGI(2) analogue, iloprost, addition of exogenous PGE(2) nor forskolin induced HAS1 or HAS2 mRNA expression in OSC1 and OSC2 cells. Furthermore, in HeLa cells after induction of COX2 by tumour necrosis factor alpha and subsequent PGE(2) release, inhibition of COX2 by etoricoxib did not affect HAS expression or HA secretion. CONCLUSIONS AND IMPLICATIONS: We conclude that in oesophageal and HeLa cancer cells, HAS1/2 expression was not responsive to the PG/cAMP pathway.

SUBMITTER: Twarock S

PROVIDER: S-EPMC2697807 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature

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Synthesis of hyaluronan in oesophageal cancer cells is uncoupled from the prostaglandin-cAMP pathway.

Twarock S S Röck K K Sarbia M M Weber A A AA Jänicke R U RU Fischer J W JW

British journal of pharmacology 20090326 2

<h4>Background and purpose</h4>Cyclooxygenase-2 (COX2) and hyaluronic acid (HA) are common in tumours and both independently promote tumour progression. Furthermore, COX2-dependent synthesis of prostaglandins (PGs) stimulates HA synthase-1 (HAS1) and HAS2 mRNA expression, together with HA synthesis via the cAMP/protein kinase A pathway in vascular smooth muscle cells. Therefore, the aim of the present study was to elucidate whether COX2-mediated PGs induce transcription of HAS isoforms in cancer ...[more]

PMID: 19338584

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Project description:The vitamin D receptor (VDR) and its ligand 1,25(OH)2D3 (1,25D) exert anti-tumor effects, but considerable heterogeneity has been reported in different model systems. In general, cell lines derived from aggressive tumor subtypes such as Triple Negative Breast Cancer (TNBC) express low levels of VDR and are less sensitive to 1,25D than those derived from more differentiated tumor types. We have previously reported that 1,25D inhibits hyaluronic acid synthase 2 (HAS2) expression and hyaluronic acid (HA) synthesis in murine TNBC cells. Here we confirmed the inhibitory effect of 1,25D on HA synthesis in human Hs578T cells representative of the mesenchymal/stem-like (MSL) subtype of TNBC. Because HA synthesis requires the production of hexoses for incorporation into HA, we predicted that the high HA production characteristic of Hs578T cells would require sustained metabolic changes through the hexosamine biosynthetic pathway (HBP). We thus examined metabolic gene expression in Hs578T cell variants sorted for High (HAHigh) and Low (HALow) HA production, and the ability of 1,25D to reverse these adaptive changes. HAHigh populations exhibited elevated HA production, smaller size, increased proliferation and higher motility than HALow populations. Despite their more aggressive phenotype, HAHigh populations retained expression of VDR protein at levels comparable to that of parental Hs578T cells and HALow subclones. Treatment with 1,25D decreased production of HA in both HAHigh and HALow populations. We also found that multiple metabolic enzymes were aberrantly expressed in HAHigh cells, especially those involved in glutamine and glucose metabolism. Notably, Glutaminase (GLS), a known oncogene for breast cancer, was strongly upregulated in HAHigh vs. HALow cells and its expression was significantly reduced by 1,25D (100 nM, 24 h). Consistent with this finding, Seahorse extracellular flux analysis indicated that respiration in HAHigh cells was significantly more dependent on exogenous glutamine than HALow cells, however, acute 1,25D exposure did not alter metabolic flux. In contrast to GLS, the glutamate transporter SLC1A7 was significantly reduced in HAHigh cells compared to HALow cells and its expression was enhanced by 1,25D. These findings support the concept that 1,25D can reverse the metabolic gene expression changes associated with HA production in cancer cells with aggressive phenotypes.

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Synthesis of hyaluronan in oesophageal cancer cells is uncoupled from the prostaglandin-cAMP pathway.

Publications

Synthesis of hyaluronan in oesophageal cancer cells is uncoupled from the prostaglandin-cAMP pathway.

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