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Characterization of STAT3 expression, signaling and inhibition in feline oral squamous cell carcinoma.

Brown ME, Bear MD, Rosol TJ, Premanandan C, Kisseberth WC, London CA - BMC Vet. Res. (2015)

Bottom Line: Exposure of SCCF2 cells to LLL12 resulted in decreased expression of pSTAT3 and total STAT3, apoptosis as assessed by caspase 3/7 activation, inhibition of colony formation and reduced expression of the STAT3 transcriptional target survivin.The OSCC cell lines with low basal STAT3 phosphorylation did not exhibit these effects, suggesting that STAT3 inhibition was responsible for the observed results.However, given the up-regulation of several STAT3 transcriptional targets following treatment, further investigation of STAT3 and its related signaling pathways in OSCC is warranted.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA.

ABSTRACT

Background: Signal transducer and activator of transcription 3 (STAT3) plays a critical role in tumor development by regulating signaling pathways involved in cell proliferation, survival, metastasis and angiogenesis. STAT3 is activated in many cancers, including head and neck squamous cell carcinoma (HNSCC) in people. Feline oral squamous cell carcinoma (OSCC) is similar to advanced or recurrent HNSCC as it is poorly responsive to traditional therapies and carries a poor long-term prognosis. The purpose of this study was to characterize expression and activation of STAT3 in feline OSCC cell lines and tumor samples and to investigate the biologic activity of a novel, allosteric STAT3 inhibitor, LLL12, in feline OSCC cell lines.

Results: We evaluated 3 feline OSCC cell lines and one of these (SCCF2) exhibited high levels of constitutive STAT3 phosphorylation and high sensitivity to LLL12 treatment. Exposure of SCCF2 cells to LLL12 resulted in decreased expression of pSTAT3 and total STAT3, apoptosis as assessed by caspase 3/7 activation, inhibition of colony formation and reduced expression of the STAT3 transcriptional target survivin. In contrast, the STAT3 transcriptional targets VEGF and MCL-1 increased after LLL12 treatment. This was, in part, likely due to LLL12 mediated upregulation of HIF-1α, which is known to drive VEGF and MCL-1 expression. The OSCC cell lines with low basal STAT3 phosphorylation did not exhibit these effects, suggesting that STAT3 inhibition was responsible for the observed results. Lastly, immunohistochemistry for pSTAT3 was performed using a feline OSCC tissue microarray, demonstrating expression in 48 % of samples tested.

Conclusions: These data demonstrate that LLL12 has biologic activity against a feline OSCC cell line expressing pSTAT3 and that STAT3 represents a target for therapeutic intervention in this disease. However, given the up-regulation of several STAT3 transcriptional targets following treatment, further investigation of STAT3 and its related signaling pathways in OSCC is warranted.

No MeSH data available.


Related in: MedlinePlus

Evaluation of feline OSCC cell lines for apoptosis following LLL12 treatment. Feline OSCC cell lines were treated with DMSO or increasing concentrations of LLL12 (0.2 – 2 μM) for 24 h. Caspase activity was assessed using SensoLyte Homogenous AMC Caspase 3/7 Assay kit. Experiments were performed in triplicate (*p < 0.05)
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Fig4: Evaluation of feline OSCC cell lines for apoptosis following LLL12 treatment. Feline OSCC cell lines were treated with DMSO or increasing concentrations of LLL12 (0.2 – 2 μM) for 24 h. Caspase activity was assessed using SensoLyte Homogenous AMC Caspase 3/7 Assay kit. Experiments were performed in triplicate (*p < 0.05)

Mentions: To determine if growth inhibition of feline OSCC cells was mediated by apoptosis, SCCF2 and SCCF3 were treated with DMSO, 0.02, 0.2, or 2 μM of LLL12 for 12 or 24 h and caspase 3/7 activity was measured. After 12 h of treatment with 0.2 μM of LLL12, SCCF2 showed a trend towards increased caspase 3/7 activity (data not shown), but this difference did not reach statistical significance until 24 h of treatment. SCCF3 showed a small, but statistically significant, increase in caspase 3/7 activity after 24 h of treatment with 2 μM of LLL12 (Fig. 4).Fig. 4


Characterization of STAT3 expression, signaling and inhibition in feline oral squamous cell carcinoma.

Brown ME, Bear MD, Rosol TJ, Premanandan C, Kisseberth WC, London CA - BMC Vet. Res. (2015)

Evaluation of feline OSCC cell lines for apoptosis following LLL12 treatment. Feline OSCC cell lines were treated with DMSO or increasing concentrations of LLL12 (0.2 – 2 μM) for 24 h. Caspase activity was assessed using SensoLyte Homogenous AMC Caspase 3/7 Assay kit. Experiments were performed in triplicate (*p < 0.05)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4536595&req=5

Fig4: Evaluation of feline OSCC cell lines for apoptosis following LLL12 treatment. Feline OSCC cell lines were treated with DMSO or increasing concentrations of LLL12 (0.2 – 2 μM) for 24 h. Caspase activity was assessed using SensoLyte Homogenous AMC Caspase 3/7 Assay kit. Experiments were performed in triplicate (*p < 0.05)
Mentions: To determine if growth inhibition of feline OSCC cells was mediated by apoptosis, SCCF2 and SCCF3 were treated with DMSO, 0.02, 0.2, or 2 μM of LLL12 for 12 or 24 h and caspase 3/7 activity was measured. After 12 h of treatment with 0.2 μM of LLL12, SCCF2 showed a trend towards increased caspase 3/7 activity (data not shown), but this difference did not reach statistical significance until 24 h of treatment. SCCF3 showed a small, but statistically significant, increase in caspase 3/7 activity after 24 h of treatment with 2 μM of LLL12 (Fig. 4).Fig. 4

Bottom Line: Exposure of SCCF2 cells to LLL12 resulted in decreased expression of pSTAT3 and total STAT3, apoptosis as assessed by caspase 3/7 activation, inhibition of colony formation and reduced expression of the STAT3 transcriptional target survivin.The OSCC cell lines with low basal STAT3 phosphorylation did not exhibit these effects, suggesting that STAT3 inhibition was responsible for the observed results.However, given the up-regulation of several STAT3 transcriptional targets following treatment, further investigation of STAT3 and its related signaling pathways in OSCC is warranted.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA.

ABSTRACT

Background: Signal transducer and activator of transcription 3 (STAT3) plays a critical role in tumor development by regulating signaling pathways involved in cell proliferation, survival, metastasis and angiogenesis. STAT3 is activated in many cancers, including head and neck squamous cell carcinoma (HNSCC) in people. Feline oral squamous cell carcinoma (OSCC) is similar to advanced or recurrent HNSCC as it is poorly responsive to traditional therapies and carries a poor long-term prognosis. The purpose of this study was to characterize expression and activation of STAT3 in feline OSCC cell lines and tumor samples and to investigate the biologic activity of a novel, allosteric STAT3 inhibitor, LLL12, in feline OSCC cell lines.

Results: We evaluated 3 feline OSCC cell lines and one of these (SCCF2) exhibited high levels of constitutive STAT3 phosphorylation and high sensitivity to LLL12 treatment. Exposure of SCCF2 cells to LLL12 resulted in decreased expression of pSTAT3 and total STAT3, apoptosis as assessed by caspase 3/7 activation, inhibition of colony formation and reduced expression of the STAT3 transcriptional target survivin. In contrast, the STAT3 transcriptional targets VEGF and MCL-1 increased after LLL12 treatment. This was, in part, likely due to LLL12 mediated upregulation of HIF-1α, which is known to drive VEGF and MCL-1 expression. The OSCC cell lines with low basal STAT3 phosphorylation did not exhibit these effects, suggesting that STAT3 inhibition was responsible for the observed results. Lastly, immunohistochemistry for pSTAT3 was performed using a feline OSCC tissue microarray, demonstrating expression in 48 % of samples tested.

Conclusions: These data demonstrate that LLL12 has biologic activity against a feline OSCC cell line expressing pSTAT3 and that STAT3 represents a target for therapeutic intervention in this disease. However, given the up-regulation of several STAT3 transcriptional targets following treatment, further investigation of STAT3 and its related signaling pathways in OSCC is warranted.

No MeSH data available.


Related in: MedlinePlus