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Open Access Research

Prognostic significance of STAT3 and phosphorylated STAT3 in human soft tissue tumors - a clinicopathological analysis

Diana David1, Lakshmy M Rajappan2, Krishna Balachandran3, Jissa V Thulaseedharan1, Asha S Nair1* and Radhakrishna M Pillai1

Author Affiliations

1 Integrated Cancer Research, Rajiv Gandhi Centre for Biotechnology, Kerala, India

2 District Public Health Laboratory, Alappuzha, Kerala, India

3 Department of Pathology, Kottayam Medical College, Kottayam, Kerala, India

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Journal of Experimental & Clinical Cancer Research 2011, 30:56  doi:10.1186/1756-9966-30-56

Published: 16 May 2011

Abstract

Background

Signal transducer and activator of transcription 3 (STAT3) is a key signaling molecule and a central cytoplasmic transcription factor, implicated in the regulation of growth. Its aberrant activation has been demonstrated to correlate with many types of human malignancy. However, whether constitutive STAT3 signaling plays a key role in the survival and growth of soft-tissue tumors is still unclear and hence needs to be elucidated further. In our study we examined the expression levels of STAT3 and pSTAT3 in different grades of soft tissue tumors and correlated with its clinicopathological characteristics.

Methods

Expression levels of STAT3 and pSTAT3 in soft tissue tumors were studied using Immunohistochemistry, Western blotting and Reverse transcriptase- PCR and correlated with its clinicopathological characteristics using Chi squared or Fisher's exact test and by logistic regression analysis. Statistical analysis was done using Intercooled Stata software (Intercooled Stata 8.2 version).

Results

Of the 82 soft tissue tumor samples, fifty four (65.8%) showed immunoreactivity for STAT3 and twenty eight (34.1%) for pSTAT3. Expression of STAT3 and pSTAT3 was significantly associated with tumor grade (P < 0.001; P < 0.001), tumor location (P = 0.025; P = 0.027), plane of tumor (P = 0.011; P = 0.006), and tumor necrosis (P = 0.001; P = 0.002). Western blotting and RT-PCR analysis showed increased expression of STAT3 and p-STAT3 as grade of malignancy increased.

Conclusion

These findings suggest that constitutive activation of STAT3 is an important factor related to carcinogenesis of human soft tissue tumors and is significantly associated with its clinicopathological parameters which may possibly have potential diagnostic implications.

Keywords:
STAT3; pSTAT3; Soft tissue tumors