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A distinct pre-existing inflammatory tumour microenvironment is associated with chemotherapy resistance in high-grade serous epithelial ovarian cancer.

Koti M, Siu A, Clément I, Bidarimath M, Turashvili G, Edwards A, Rahimi K, Mes-Masson AM, Masson AM, Squire JA - Br. J. Cancer (2015)

Bottom Line: A total of 11 significantly differentially expressed genes were found to distinguish the two groups.As STAT1 was the most significantly differentially expressed gene (P=0.003), we validated the expression of STAT1 protein by immunohistochemistry using an independent cohort of 183 (52 resistant and 131 sensitive) HGSC cases on a primary tumour tissue microarray.Relative expression levels were subjected to Kaplan-Meier survival analysis and Cox proportional hazard regression models.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.

ABSTRACT

Background: Chemotherapy resistance is a major determinant of poor overall survival rates in high-grade serous ovarian cancer (HGSC). We have previously shown that gene expression alterations affecting the NF-κB pathway characterise chemotherapy resistance in HGSC, suggesting that the regulation of an immune response may be associated with this phenotype.

Methods: Given that intrinsic drug resistance pre-exists and is governed by both tumour and host factors, the current study was performed to examine the cross-talk between tumour inflammatory microenvironment and cancer cells, and their roles in mediating differential chemotherapy response in HGSC patients. Expression profiling of a panel of 184 inflammation-related genes was performed in 15 chemoresistant and 19 chemosensitive HGSC tumours using the NanoString nCounter platform.

Results: A total of 11 significantly differentially expressed genes were found to distinguish the two groups. As STAT1 was the most significantly differentially expressed gene (P=0.003), we validated the expression of STAT1 protein by immunohistochemistry using an independent cohort of 183 (52 resistant and 131 sensitive) HGSC cases on a primary tumour tissue microarray. Relative expression levels were subjected to Kaplan-Meier survival analysis and Cox proportional hazard regression models.

Conclusions: This study confirms that higher STAT1 expression is significantly associated with increased progression-free survival and that this protein together with other mediators of tumour-host microenvironment can be applied as a novel response predictive biomarker in HGSC. Furthermore, an overall underactive immune microenvironment suggests that the pre-existing state of the tumour immune microenvironment could determine response to chemotherapy in HGSC.

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Immunohistochemical analysis of STAT1 in HGSC. (A) The STAT1 antibody (Abcam no. ab2415, polyclonal rabbit anti-human STAT1) optimisation by IHC was performed in (a) normal adjacent to prostate tumour tissue (showing negative staining), (b) HGS ovarian tissue (showing negative staining) and (c) HGS ovarian tissue (showing positive staining). (B) Independent validation of STAT1 expression was performed on an HGSC tissue microarray. Representative IHC images of overall STAT1 expression in HGSC. (a) Tissue punch scored as 0 negative/absent, (b) tissue punch scored as 1 with weak expression, (c) tissue punch scored as 2 for moderate expression and (d) tissue punch scored as 3 for strong expression.
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fig3: Immunohistochemical analysis of STAT1 in HGSC. (A) The STAT1 antibody (Abcam no. ab2415, polyclonal rabbit anti-human STAT1) optimisation by IHC was performed in (a) normal adjacent to prostate tumour tissue (showing negative staining), (b) HGS ovarian tissue (showing negative staining) and (c) HGS ovarian tissue (showing positive staining). (B) Independent validation of STAT1 expression was performed on an HGSC tissue microarray. Representative IHC images of overall STAT1 expression in HGSC. (a) Tissue punch scored as 0 negative/absent, (b) tissue punch scored as 1 with weak expression, (c) tissue punch scored as 2 for moderate expression and (d) tissue punch scored as 3 for strong expression.

Mentions: A total of 183 tumours were available for STAT1 IHC staining analysis based on the same classification criteria used previously (Liu and Matulonis, 2006; Wang et al, 2012). Following antibody optimisation (Figure 3A) a semiquantitative score from 0 to 3 (Figure 3B) was utilised to determine the overall staining intensity for the STAT1 protein. Log-rank test analysis revealed a significant (P=0.02) association between low STAT1 expression and decreased progression-free survival (Figure 4). These data provide additional evidence that elevated STAT1 expression together with other genes involved in the Th1 immune response may be investigated more extensively as biomarkers able to predict chemotherapy response in HGSC. Although a significant association between levels of STAT1 expression was noted upon comparison of FIGO stages I and II (Figure 5A), the difference in expression was not significant when stages III and IV were compared. Distinct STAT1 expression at the earlier stages I and II suggests that genotypic heterogeneity during tumour progression and/or the presence of a temporal element underlying the mechanism of cancer immunoediting may abrogate the need for differential STAT1 expression at later stages of the disease. Furthermore, Kaplan–Meier analysis also showed a trend, approaching significance, between decreased STAT1 expression and shorter overall survival compared with patients with longer overall survival (Figure 5B). Additional validation studies in larger cohorts are needed to confirm these findings.


A distinct pre-existing inflammatory tumour microenvironment is associated with chemotherapy resistance in high-grade serous epithelial ovarian cancer.

Koti M, Siu A, Clément I, Bidarimath M, Turashvili G, Edwards A, Rahimi K, Mes-Masson AM, Masson AM, Squire JA - Br. J. Cancer (2015)

Immunohistochemical analysis of STAT1 in HGSC. (A) The STAT1 antibody (Abcam no. ab2415, polyclonal rabbit anti-human STAT1) optimisation by IHC was performed in (a) normal adjacent to prostate tumour tissue (showing negative staining), (b) HGS ovarian tissue (showing negative staining) and (c) HGS ovarian tissue (showing positive staining). (B) Independent validation of STAT1 expression was performed on an HGSC tissue microarray. Representative IHC images of overall STAT1 expression in HGSC. (a) Tissue punch scored as 0 negative/absent, (b) tissue punch scored as 1 with weak expression, (c) tissue punch scored as 2 for moderate expression and (d) tissue punch scored as 3 for strong expression.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385963&req=5

fig3: Immunohistochemical analysis of STAT1 in HGSC. (A) The STAT1 antibody (Abcam no. ab2415, polyclonal rabbit anti-human STAT1) optimisation by IHC was performed in (a) normal adjacent to prostate tumour tissue (showing negative staining), (b) HGS ovarian tissue (showing negative staining) and (c) HGS ovarian tissue (showing positive staining). (B) Independent validation of STAT1 expression was performed on an HGSC tissue microarray. Representative IHC images of overall STAT1 expression in HGSC. (a) Tissue punch scored as 0 negative/absent, (b) tissue punch scored as 1 with weak expression, (c) tissue punch scored as 2 for moderate expression and (d) tissue punch scored as 3 for strong expression.
Mentions: A total of 183 tumours were available for STAT1 IHC staining analysis based on the same classification criteria used previously (Liu and Matulonis, 2006; Wang et al, 2012). Following antibody optimisation (Figure 3A) a semiquantitative score from 0 to 3 (Figure 3B) was utilised to determine the overall staining intensity for the STAT1 protein. Log-rank test analysis revealed a significant (P=0.02) association between low STAT1 expression and decreased progression-free survival (Figure 4). These data provide additional evidence that elevated STAT1 expression together with other genes involved in the Th1 immune response may be investigated more extensively as biomarkers able to predict chemotherapy response in HGSC. Although a significant association between levels of STAT1 expression was noted upon comparison of FIGO stages I and II (Figure 5A), the difference in expression was not significant when stages III and IV were compared. Distinct STAT1 expression at the earlier stages I and II suggests that genotypic heterogeneity during tumour progression and/or the presence of a temporal element underlying the mechanism of cancer immunoediting may abrogate the need for differential STAT1 expression at later stages of the disease. Furthermore, Kaplan–Meier analysis also showed a trend, approaching significance, between decreased STAT1 expression and shorter overall survival compared with patients with longer overall survival (Figure 5B). Additional validation studies in larger cohorts are needed to confirm these findings.

Bottom Line: A total of 11 significantly differentially expressed genes were found to distinguish the two groups.As STAT1 was the most significantly differentially expressed gene (P=0.003), we validated the expression of STAT1 protein by immunohistochemistry using an independent cohort of 183 (52 resistant and 131 sensitive) HGSC cases on a primary tumour tissue microarray.Relative expression levels were subjected to Kaplan-Meier survival analysis and Cox proportional hazard regression models.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.

ABSTRACT

Background: Chemotherapy resistance is a major determinant of poor overall survival rates in high-grade serous ovarian cancer (HGSC). We have previously shown that gene expression alterations affecting the NF-κB pathway characterise chemotherapy resistance in HGSC, suggesting that the regulation of an immune response may be associated with this phenotype.

Methods: Given that intrinsic drug resistance pre-exists and is governed by both tumour and host factors, the current study was performed to examine the cross-talk between tumour inflammatory microenvironment and cancer cells, and their roles in mediating differential chemotherapy response in HGSC patients. Expression profiling of a panel of 184 inflammation-related genes was performed in 15 chemoresistant and 19 chemosensitive HGSC tumours using the NanoString nCounter platform.

Results: A total of 11 significantly differentially expressed genes were found to distinguish the two groups. As STAT1 was the most significantly differentially expressed gene (P=0.003), we validated the expression of STAT1 protein by immunohistochemistry using an independent cohort of 183 (52 resistant and 131 sensitive) HGSC cases on a primary tumour tissue microarray. Relative expression levels were subjected to Kaplan-Meier survival analysis and Cox proportional hazard regression models.

Conclusions: This study confirms that higher STAT1 expression is significantly associated with increased progression-free survival and that this protein together with other mediators of tumour-host microenvironment can be applied as a novel response predictive biomarker in HGSC. Furthermore, an overall underactive immune microenvironment suggests that the pre-existing state of the tumour immune microenvironment could determine response to chemotherapy in HGSC.

Show MeSH
Related in: MedlinePlus