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Abrogation of IL-6-mediated JAK signalling by the cyclopentenone prostaglandin 15d-PGJ(2) in oral squamous carcinoma cells.

Siavash H, Nikitakis NG, Sauk JJ - Br. J. Cancer (2004)

Bottom Line: Importantly, 15d-PGJ(2) selectively abrogated constitutive and IL-6-mediated JAK phosphorylation without affecting EGFR-activated levels.Moreover, the inhibitory effect of 15d-PGJ(2) on JAK signalling required the reactive alpha,beta-unsaturated carbon within the cyclopentenone ring.Targeting of JAK signalling using a specific JAK inhibitor also abolished Stat3 phosphorylation and resulted in apoptosis in oral SCC cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences, University of Maryland, Baltimore, MD 21201, USA. hsiav001@umaryland.edu

ABSTRACT
Cyclopentenone 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) exerts antineoplastic effects on various types of human cancer. We recently showed that treatment with 15d-PGJ(2) induces apoptosis accompanied by downregulation of the oncogenic signal transducer and activator of transcription 3 (Stat3) signalling in human oral squamous cell carcinoma (SCC) cells. The current study examines the effects of 15d-PGJ(2) on the epidermal growth factor receptor (EGFR) and Janus Kinase (JAK)-mediated signalling pathways. Inhibition of Stat3 by 15d-PGJ(2) was abolished by exogenous stimulation with transforming growth factor alpha (TGF-alpha), but not interleukin 6 (IL-6), supporting a selective effect of 15d-PGJ(2) on IL-6-mediated signalling. Importantly, 15d-PGJ(2) selectively abrogated constitutive and IL-6-mediated JAK phosphorylation without affecting EGFR-activated levels. Moreover, the inhibitory effect of 15d-PGJ(2) on JAK signalling required the reactive alpha,beta-unsaturated carbon within the cyclopentenone ring. Targeting of JAK signalling using a specific JAK inhibitor also abolished Stat3 phosphorylation and resulted in apoptosis in oral SCC cells. Our findings provide the first evidence for 15d-PGJ(2)-mediated downregulation of constitutive and IL-6-induced JAK signalling in cancer and support that JAK inhibition and suppression of EGFR-independent Stat3 activation by 15d-PGJ(2) represent a promising approach for induction of apoptosis in oral SCC cells.

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15d-PGJ2-mediated inhibition of JAK/Stat3 signalling requires the reactive cyclopentenone ring system. (A) Structure of 9,10-dihydro-15-Deoxy-Δ12,14-PGJ2 (CAY10410) and 15d-PGJ2. (B) 15d-PGJ2, but not CAY10410, abrogates constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were treated with NM, AG490 (50 μM), 15d-PGJ2 (20 μM) or CAY10410 (40 μM) for 10 min. Cell lysates were immunoprecipitated with Jak1 antibody and Western blotted for phosphorylated (PY) and total Jak1. (C) Effect of CAY10410 on Stat3 phosphorylation. Oral SCC9 cells were treated with NM, 15d-PGJ2 (20 μM) or CAY10410 (20 and 40 μM) for 45 min. Cells were blotted with phospho-Stat3 antibody (Y705) and subsequently stripped and reprobed with Stat3 antibody.
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fig4: 15d-PGJ2-mediated inhibition of JAK/Stat3 signalling requires the reactive cyclopentenone ring system. (A) Structure of 9,10-dihydro-15-Deoxy-Δ12,14-PGJ2 (CAY10410) and 15d-PGJ2. (B) 15d-PGJ2, but not CAY10410, abrogates constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were treated with NM, AG490 (50 μM), 15d-PGJ2 (20 μM) or CAY10410 (40 μM) for 10 min. Cell lysates were immunoprecipitated with Jak1 antibody and Western blotted for phosphorylated (PY) and total Jak1. (C) Effect of CAY10410 on Stat3 phosphorylation. Oral SCC9 cells were treated with NM, 15d-PGJ2 (20 μM) or CAY10410 (20 and 40 μM) for 45 min. Cells were blotted with phospho-Stat3 antibody (Y705) and subsequently stripped and reprobed with Stat3 antibody.

Mentions: 15d-PGJ2 abrogates JAK phosphorylation in oral SCC cells. (A) 15d-PGJ2 abrogates IL-6-induced JAK phosphorylation in oral SCC cells. Oral SCC25 cells were treated with NM, or rIL-6 (25 ng ml−1) for 5 or 10 min in the presence or absence of pretreatment with 15d-PGJ2 (20 μM) for 30 min, followed by immunoprecipitation for Jak1 and Western blotting for phosphorylated (PY) and total Jak1. For Jak2, cell lysates were blotted with phospho-Jak2 (Y1007, Y1008) antibody and subsequently stripped and reprobed with Jak2 antibody. (B) 15d-PGJ2 inhibits constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were either untreated or treated with 15d-PGJ2 (20 μM) for 5 min, 10 min, 20 min, 30 min and 1 h. (C) Effect of AG490 on constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were either untreated or treated with AG490 (50 μM) for 5 min, 10 min, 20 min, 30 min and 1 h. In (B) and (C), cell lysates were blotted with phospho-Jak2 (Y1007, Y1008) antibody and subsequently stripped and reprobed with Jak2 antibody.


Abrogation of IL-6-mediated JAK signalling by the cyclopentenone prostaglandin 15d-PGJ(2) in oral squamous carcinoma cells.

Siavash H, Nikitakis NG, Sauk JJ - Br. J. Cancer (2004)

15d-PGJ2-mediated inhibition of JAK/Stat3 signalling requires the reactive cyclopentenone ring system. (A) Structure of 9,10-dihydro-15-Deoxy-Δ12,14-PGJ2 (CAY10410) and 15d-PGJ2. (B) 15d-PGJ2, but not CAY10410, abrogates constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were treated with NM, AG490 (50 μM), 15d-PGJ2 (20 μM) or CAY10410 (40 μM) for 10 min. Cell lysates were immunoprecipitated with Jak1 antibody and Western blotted for phosphorylated (PY) and total Jak1. (C) Effect of CAY10410 on Stat3 phosphorylation. Oral SCC9 cells were treated with NM, 15d-PGJ2 (20 μM) or CAY10410 (20 and 40 μM) for 45 min. Cells were blotted with phospho-Stat3 antibody (Y705) and subsequently stripped and reprobed with Stat3 antibody.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2747713&req=5

fig4: 15d-PGJ2-mediated inhibition of JAK/Stat3 signalling requires the reactive cyclopentenone ring system. (A) Structure of 9,10-dihydro-15-Deoxy-Δ12,14-PGJ2 (CAY10410) and 15d-PGJ2. (B) 15d-PGJ2, but not CAY10410, abrogates constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were treated with NM, AG490 (50 μM), 15d-PGJ2 (20 μM) or CAY10410 (40 μM) for 10 min. Cell lysates were immunoprecipitated with Jak1 antibody and Western blotted for phosphorylated (PY) and total Jak1. (C) Effect of CAY10410 on Stat3 phosphorylation. Oral SCC9 cells were treated with NM, 15d-PGJ2 (20 μM) or CAY10410 (20 and 40 μM) for 45 min. Cells were blotted with phospho-Stat3 antibody (Y705) and subsequently stripped and reprobed with Stat3 antibody.
Mentions: 15d-PGJ2 abrogates JAK phosphorylation in oral SCC cells. (A) 15d-PGJ2 abrogates IL-6-induced JAK phosphorylation in oral SCC cells. Oral SCC25 cells were treated with NM, or rIL-6 (25 ng ml−1) for 5 or 10 min in the presence or absence of pretreatment with 15d-PGJ2 (20 μM) for 30 min, followed by immunoprecipitation for Jak1 and Western blotting for phosphorylated (PY) and total Jak1. For Jak2, cell lysates were blotted with phospho-Jak2 (Y1007, Y1008) antibody and subsequently stripped and reprobed with Jak2 antibody. (B) 15d-PGJ2 inhibits constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were either untreated or treated with 15d-PGJ2 (20 μM) for 5 min, 10 min, 20 min, 30 min and 1 h. (C) Effect of AG490 on constitutive JAK phosphorylation in oral SCC cells. Oral SCC9 cells were either untreated or treated with AG490 (50 μM) for 5 min, 10 min, 20 min, 30 min and 1 h. In (B) and (C), cell lysates were blotted with phospho-Jak2 (Y1007, Y1008) antibody and subsequently stripped and reprobed with Jak2 antibody.

Bottom Line: Importantly, 15d-PGJ(2) selectively abrogated constitutive and IL-6-mediated JAK phosphorylation without affecting EGFR-activated levels.Moreover, the inhibitory effect of 15d-PGJ(2) on JAK signalling required the reactive alpha,beta-unsaturated carbon within the cyclopentenone ring.Targeting of JAK signalling using a specific JAK inhibitor also abolished Stat3 phosphorylation and resulted in apoptosis in oral SCC cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences, University of Maryland, Baltimore, MD 21201, USA. hsiav001@umaryland.edu

ABSTRACT
Cyclopentenone 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) exerts antineoplastic effects on various types of human cancer. We recently showed that treatment with 15d-PGJ(2) induces apoptosis accompanied by downregulation of the oncogenic signal transducer and activator of transcription 3 (Stat3) signalling in human oral squamous cell carcinoma (SCC) cells. The current study examines the effects of 15d-PGJ(2) on the epidermal growth factor receptor (EGFR) and Janus Kinase (JAK)-mediated signalling pathways. Inhibition of Stat3 by 15d-PGJ(2) was abolished by exogenous stimulation with transforming growth factor alpha (TGF-alpha), but not interleukin 6 (IL-6), supporting a selective effect of 15d-PGJ(2) on IL-6-mediated signalling. Importantly, 15d-PGJ(2) selectively abrogated constitutive and IL-6-mediated JAK phosphorylation without affecting EGFR-activated levels. Moreover, the inhibitory effect of 15d-PGJ(2) on JAK signalling required the reactive alpha,beta-unsaturated carbon within the cyclopentenone ring. Targeting of JAK signalling using a specific JAK inhibitor also abolished Stat3 phosphorylation and resulted in apoptosis in oral SCC cells. Our findings provide the first evidence for 15d-PGJ(2)-mediated downregulation of constitutive and IL-6-induced JAK signalling in cancer and support that JAK inhibition and suppression of EGFR-independent Stat3 activation by 15d-PGJ(2) represent a promising approach for induction of apoptosis in oral SCC cells.

Show MeSH
Related in: MedlinePlus