Limits...
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

Immunohistochemistry for pSTAT3 in primary feline OSCC tumor samples. Immunohistochemistry was performed for pSTAT3 using a tissue microarray of feline OSCC tumor samples. Signal intensity and percent positivity were scored; these scores were added to generate a total score. Examples of no (a), mild (b) and moderate (c) signal intensity are shown (20X). d pSTAT3 immunoreactivity was also observed in adjacent gingiva in 4 OSCC samples (10X)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig8: Immunohistochemistry for pSTAT3 in primary feline OSCC tumor samples. Immunohistochemistry was performed for pSTAT3 using a tissue microarray of feline OSCC tumor samples. Signal intensity and percent positivity were scored; these scores were added to generate a total score. Examples of no (a), mild (b) and moderate (c) signal intensity are shown (20X). d pSTAT3 immunoreactivity was also observed in adjacent gingiva in 4 OSCC samples (10X)

Mentions: To assess the prevalence of STAT3 activation in primary feline OSCC samples, a tissue microarray was constructed from 37 archived feline OSCC surgical biopsies and immunohistochemical staining for pSTAT3 was performed. Signal intensity and percent positivity were scored; these scores were added to generate a total score. Examples of no, mild and moderate signal intensity are shown in Figures 8a-c. Total scores of greater than or equal to 2 were considered positive. Of 37 samples, 27 had adequate tumor tissue for evaluation and 13 of these 27 (48.1 %) samples were considered positive. In 9 of the 13 positive samples, immunoreactivity was detected in 5–20 % of OSCC cells, while 3 and 1 sample displayed immunoreactivity in 20–50 % and 50–100 % of cells, respectively. In 4 samples, pSTAT3 expression was also observed in adjacent gingiva (Fig. 8d), although 2 of these 4 samples were considered to have inadequate tumor sample and were excluded from analysis. The results of the TMA scoring are summarized in Additional file 1: Table S2.Fig. 8


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)

Immunohistochemistry for pSTAT3 in primary feline OSCC tumor samples. Immunohistochemistry was performed for pSTAT3 using a tissue microarray of feline OSCC tumor samples. Signal intensity and percent positivity were scored; these scores were added to generate a total score. Examples of no (a), mild (b) and moderate (c) signal intensity are shown (20X). d pSTAT3 immunoreactivity was also observed in adjacent gingiva in 4 OSCC samples (10X)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig8: Immunohistochemistry for pSTAT3 in primary feline OSCC tumor samples. Immunohistochemistry was performed for pSTAT3 using a tissue microarray of feline OSCC tumor samples. Signal intensity and percent positivity were scored; these scores were added to generate a total score. Examples of no (a), mild (b) and moderate (c) signal intensity are shown (20X). d pSTAT3 immunoreactivity was also observed in adjacent gingiva in 4 OSCC samples (10X)
Mentions: To assess the prevalence of STAT3 activation in primary feline OSCC samples, a tissue microarray was constructed from 37 archived feline OSCC surgical biopsies and immunohistochemical staining for pSTAT3 was performed. Signal intensity and percent positivity were scored; these scores were added to generate a total score. Examples of no, mild and moderate signal intensity are shown in Figures 8a-c. Total scores of greater than or equal to 2 were considered positive. Of 37 samples, 27 had adequate tumor tissue for evaluation and 13 of these 27 (48.1 %) samples were considered positive. In 9 of the 13 positive samples, immunoreactivity was detected in 5–20 % of OSCC cells, while 3 and 1 sample displayed immunoreactivity in 20–50 % and 50–100 % of cells, respectively. In 4 samples, pSTAT3 expression was also observed in adjacent gingiva (Fig. 8d), although 2 of these 4 samples were considered to have inadequate tumor sample and were excluded from analysis. The results of the TMA scoring are summarized in Additional file 1: Table S2.Fig. 8

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