Expression levels of HER2 and MRP1 are not prognostic factors of long‑term survival in 829 patients with esophageal squamous cell carcinoma

  • Authors:
    • Yong Chen
    • Shuang‑Mei Zhu
    • Xiao‑Ling Xu
    • An Zhao
    • Jin‑Lin Hu
  • View Affiliations

  • Published online on: November 25, 2015     https://doi.org/10.3892/ol.2015.3975
  • Pages: 745-752
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Abstract

Esophageal squamous cell carcinoma (ESCC) is the eighth most frequent neoplasm in China. However, the expression levels of human epidermal growth factor receptor 2 (HER2) and multidrug resistance protein 1 (MRP1) in patients with ESCC remain to be determined. In the present study, 829 ESCC cases were evaluated using immunohistochemistry. The association between the expression levels of HER2 and MRP1 and the patient's clinicopathological factors was analyzed using Fisher's exact test or χ2 test. Univariate analysis was performed via Kaplan‑Meier survival curves, while the Cox proportional hazard model was used for multivariate analysis. A significant correlation was observed between the expression levels of HER2 and the patient's gender (P<0.050), tumor size (P=0.013) and venous/lymphatic invasion (P=0.039). However, no significant correlation was identified between the expression levels of MRP1 and the clinicopathological factors of the patients. In univariate analysis, gender, differentiation, depth of invasion, clinical stage, adjuvant radiotherapy or chemotherapy and lymph node metastasis were significantly correlated with progression‑free survival (PFS) and overall survival (OS) in patients with ESCC (P<0.050). The graphical representation of the Kaplan‑Meier estimate curves suggested that the expression levels of HER2 or MRP1 did not exert any influence on prognosis (log‑rank test, P>0.050). In multivariate analysis, tumor location, gender, clinical stage, differentiation and lymph node metastasis were identified as independent factors of prognosis in patients with ESCC (P<0.050). However, the expression levels of HER2 or MRP1 were not independently associated with PFS or OS in these patients. In conclusion, the present large‑scale study demonstrates that the protein expression levels of HER2 and MRP1 does not exert any influence on the prognosis of ESCC.

Introduction

Esophageal carcinoma (EC) is one of the most common malignancies in the world, while esophageal squamous cell carcinoma (ESCC) is the main histopathological subtype of EC in Eastern Asian countries, including China (1). Although the therapeutic treatments for ESCC such as surgery, chemotherapy, radiotherapy and target therapy, have improved in recent years, the five-year survival rate for patients with resectable disease is <40% (2,3). Thus, an increasing interest exist on the prognostic and therapeutic value of biological markers that participate in the carcinogenesis and progression of ESCC.

Human epidermal growth factor receptor (EGFR) 2 (HER2), also known as Erb-B2 receptor tyrosine kinase 2 and c-erbB2, is a member of the EGFR family, whose abnormal activation appears to be involved in tumor development and progression in ESCC (4,5). In addition, HER2 is a therapeutic target in several types of cancer. Previous studies have observed that the oncogene HER2/neu was overexpressed in 2.0–19.1% cases of ESCC (613), and increased protein expression levels of HER2 have been previously observed in EC (14,15) and ESCC (6,7). However, the role of HER2 in ESCC remains controversial (6,7,9,10,12,1619). Multidrug resistance protein 1 (MRP1), as a member of the adenosine triphosphate-binding cassette transporter family, has been implicated in resistance to cancer therapeutics (20). High expression levels of MRP1 have been observed in various solid tumors such as lung cancer, and the expression levels of MRP1 have been reported to inversely correlate with prognosis in patients with lung cancer (2123). In addition, patients with Barrett's carcinoma treated with neoadjuvant chemotherapy who exhibited high messenger RNA expression levels of MRP1 presented prolonged survival, compared with those patients whose levels of MRP1 were low (24). However the role of MRP1 expression in patients with ESCC remains unclear.

The aim of the present retrospective study was to determine the clinical significance of HER2 and MRP1 expression in a large-scale cohort study involving patients with ESCC who had undergone surgical resection. For that purpose, the protein expression levels of HER2 and MRP1 were detected by immunohistochemistry (IHC), and the association between the clinicopathological features of this disease and the prognostic value of HER2 and MRP1 expression in patients with ESCC was evaluated.

Materials and methods

Patients

Between June 2002 and June 2010, all the consecutive cases of patients with clinical resectable ESCC who had been treated at the Department of Medical Oncology of Zhejiang Cancer Hospital (Hangzhou, China) were retrospectively reviewed. The present study was approved by the institutional review board of Zhejiang Cancer Hospital, and all the patients provided written informed consent for participation in the study. All the patients included in the study had been subjected to complete resection, and none had received neoadjuvant treatment. Those patients who succumbed to the disease within 30 days following surgery were excluded from the study. Cancer stage was determined during the postoperative pathological examination, and included the status of primary tumor invasion, regional lymph nodes and distant metastases, according to the 7th edition of the Cancer Staging Manual published by the American Joint Committee on Cancer (25). Long-term postoperative follow-up consisted of a telephone interview conducted every three months for the first three years, every six months during the fourth and fifth year, and every year thereafter. The date of the last follow-up was April 30, 2014. Overall survival (OS) was defined from the time of diagnosis until the date of mortality or until the date of the last follow-up visit. Progression-free survival (PFS) was measured from the time of completion of the surgery until the time of documented tumor recurrence or mortality. The present study was conducted according to the REporting recommendations for tumor MARKer prognostic studies guidelines (26).

Immunohistochemistry

Immunohistochemical analyses were performed by the avidin-biotin peroxidase method, using ultraView Universal DAB Detection Kit (Ventana Medical Systems, Inc., Tucson, AZ, USA). For this purpose, paraffin sections of 4 mm thickness were excised from paraffin blocks, and subsequently immunostained with rabbit monoclonal primary antibodies against HER2 (catalogue no. 4B5; dilution, 1:100; Roche Diagnostics GmbH, Mannheim, Germany) and MRP1 (catalogue no. H-70; dilution, 1:100; Santa Cruz Biotechnology, Inc., Dallas, TX, USA). The primary antibodies were detected with an automated staining system (BenchMark XT; Roche Diagnostics GmbH).

Next, the slides were washed with phosphate-buffered saline (PBS) three times, and incubated with the secondary antibody provided in the ultraView DAB Detection Kit (Fuzhou Maixin Biotech. Co., Ltd, Fujian, China). The colorimetric reaction was developed with 3,3′-diaminobenzidine. Counterstaining was performed with hematoxylin. All steps were conducted at room temperature. For the negative control, the primary antibody was replaced with PBS.

The immunostaining results were independently examined by two clinical pathologists who were blinded to the patients' information, using a DM4000B light microscope (Leica, Wetzlar, Germany). For each sample, five high-power fields (magnification, ×400) were randomly selected. The percentage of positive cells and the intensity of the staining were assessed, and a semi-quantitatively score ranging from 0 to 3 was assigned to the samples accordingly. The staining intensity was scored as follows: i) 0, no staining; ii) 1, weak staining; iii) 2, moderate staining; and iv) 3, strong staining. This score was then multiplied by the percentage of positively stained cells present in the sample, as follows: i) 0, no staining; ii) 1, ≤10% of stained cells; iii) 2, 11–25% of stained cells; iv) 3, 26–50% of stained cells; and v) 4, ≥51% of stained cells. The resulting scores were used to classify the samples as follows: i) 0, negative staining; ii) 1–4, weak positive staining; iii) 5–8, moderate staining; and iv) 9–12, strong positive staining.

Statistical analysis

The correlation between the expression levels of HER2 and MRP1 and the patient's clinicopathological factors was analyzed using Fisher's exact test or χ2 test. Univariate and multivariate analyses were performed with Kaplan-Meier survival curves and Cox proportional hazard model, respectively. Log-rank test was used to evaluate the significance of the differences observed between pairs of survival probabilities. P<0.050 was considered to indicate a statistically significant difference. Statistical data were calculated with SPSS version 18.0 software (SPSS Inc., Chicago, IL, USA).

Results

Patient's characteristics

The cohort of 829 patients with ESCC whose expression levels of MRP1 were analyzed in the present study exhibited a female:male ratio of 1.0:4.5 and a median age of 59 years (range, 34–78 years). Among the 829 patients, 768 patients also detected HER-2 expression. ESCC was observed to be well differentiated in 110 cases (13.3%), moderately differentiated in 561 cases (67.7%), poorly differentiated in 153 cases (18.4%) and undifferentiated in 5 cases (0.6%). The enrolled patients were staged pathologically as I (n=61), II (n=335) and III (n=433). Complete resection was confirmed histologically in all patients. Locoregional lymph node metastasis was observed in 477 patients (57.5%). A total of 260 patients who presented poor prognostic factors, metastatic disease or recurrence following operation, received adjuvant radiotherapy and/or chemotherapy subsequently to surgery. A total of 762 patients were available for survival analysis, with a median duration of postoperative follow-up of 32 months (range, 1.03–102.00 months). Among them, 733 patients were followed-up for >3 years. The clinicopathological factors, staging and survival of the patients included in the present study have been previously reported (27,28).

Association between HER2 and MRP1 expression and clinicopathological features

In ESCC tissues, HER2 exhibited membrane staining, while MRP1 displayed membrane and cytoplasmic staining (Fig. 1). A total of 768 patients were available for evaluation of HER2 expression. Among them, 543 cases (70.7%) were observed to be negative, 170 cases (22.1%) were scored as 1, 37 cases (4.8%) as 2 and 18 cases (2.3%) as 3. For statistical analysis, samples with a final score of 0 were considered to exhibit low expression levels of HER2, whereas those with a final score of 1–3 were considered to display high expression levels of HER2. Among the 829 cases who were assessed for MRP1 expression by IHC, 326 (39.3%), 291 (35.1%), 144 (17.4%) and 68 (8.2%) cases were scored as 0, 1, 2 and 3, respectively. For statistical analysis, samples with a final score of 0 or 1 were considered to exhibit low expression levels of MRP1, while those with a final score of 2 or 3 were considered to display high expression levels of MRP1.

The associations between the expression levels of HER2 and MRP1 and the clinicopathological features of the patients are presented in Table I. A significant correlation was observed between the expression levels of HER2 and gender (P<0.050), tumor size (P=0.013) and venous/lymphatic invasion (P=0.039). However, no significant correlation was identified between MRP1 expression and any of the clinicopathological factors analyzed. Furthermore, high expression levels of HER2 were positively correlated with high expression levels of MRP1 (P=0.001).

Table I.

Analysis of the association between the expression levels of HER2 and MRP1 and the clinicopathological features of patients with esophageal squamous cell carcinoma.

Table I.

Analysis of the association between the expression levels of HER2 and MRP1 and the clinicopathological features of patients with esophageal squamous cell carcinoma.

HER2 expression levels (no. of patients)MRP1 expression levels (no. of patients)


CharacteristicsTotalLowHighP-valueTotalLowHighP-value
Gender 0.000 0.516
  Male627466161 678499179
  Female141  77  64 151115  36
Age (years) 0.760 0.702
  ≥55491349142 527388139
  <55277194  83 302226  76
Smoking 0.163 0.532
  Never179134  45 202153  49
  Ever589409180 627461166
Alcohol consumption 0.178 0.755
  Never256189  67 282207  75
  Ever512354158 547407140
Differentiation 0.216 0.055
  Intermediate/well622447175 671507164
  Poor/undifferentiated144  96  48 158107  51
Tumor size (cm) 0.013 0.671
  <5442297145 464341123
  ≥5326246  80 365273  92
Depth of invasion 0.678 0.362
  T1+T2160111  49 171122  49
  T3608432176 658492166
Lymph node metastasis 0.347 0.126
  N0321232  89 352273  79
  N1214148  66 232162  70
  N2159106  53 169120  49
  N3  74  57  17   76  59  17
Clinical stage 0.647 0.456
  I+II358256102 396298  98
  III410287123 433316117
Venous/lymphatic invasion 0.039 0.094
  No622450172 672506166
  Yes146  93  53 157108  49
Perineural invasion 0.050 0.219
  No588426162 638466172
  Yes180117  63 191148  43
Adjuvant radio/chemotherapy 0.269 0.196
  No517359158 569429140
  Yes251184  67 260185  75

[i] HER2, human epidermal growth factor receptor 2; MRP1, multidrug resistance protein 1.

Survival analysis

During the follow-up, 397 patients succumbed to ESCC, while recurrence or metastasis occurred in 470 patients. The metastatic areas included the supraclavicular lymph node, mediastinal lymph node, liver, lung, skeleton and brain.

In univariate analysis, gender, differentiation, depth of invasion, clinical stage, adjuvant radiotherapy or chemotherapy and lymph node metastasis were significantly correlated with the patients' PFS and OS (P<0.050) (Table II). However, the graphic pattern of the Kaplan-Meier estimate curves (Fig. 2) suggested that the expression levels of HER2 or MRP1 did not have any impact on prognosis (log-rank, P>0.050). In multivariate analysis, tumor location, clinical stage and lymph node metastasis were identified as independent factors of prognosis in patients with ESCC (Table III). However, the expression levels of HER2 or MRP1 were not observed to be independently associated with PFS and OS in these patients (Table III).

Table II.

Univariate analysis of factors that influence the survival of patients with esophageal squamous cell carcinoma.

Table II.

Univariate analysis of factors that influence the survival of patients with esophageal squamous cell carcinoma.

Progression-free survivalOverall survival


FactorsNo. of patientsP-valueNo. of patientsP-value
Gender 0.009 0.018
  Male554 645
  Female108 129
Age (years) 0.339 0.843
  ≥55416 491
  <55246 283
Smoking 0.315 0.177
  Never156 186
  Ever506 588
Alcohol consumption 0.869 0.199
  Never218 266
  Ever444 508
Location 0.400 0.149
  Upper/middle274 338
  Lower388 436
Differentiation 0.000 0.000
  Intermediate/well528 618
  Poor/undifferentiated134 155
Tumor size (cm) 0.164 0.023
  <5369 444
  ≥5293 330
Depth of invasion 0.000 0.000
  T1+T2131 168
  T3531 606
Lymph node metastasis 0.000 0.000
  N0261 331
  N1178 212
  N2152 160
  N3  71   71
Clinical stage 0.000 0.000
  I+II297 374
  III365 400
Venous/lymphatic invasion 0.473 0.373
  No531 629
  Yes131 145
Perineural invasion 0.203 0.919
  No531 604
  Yes131 170
Adjuvant radio/chemotherapy 0.049 0.002
  No425 524
  Yes237 250
Human epidermal growth factor receptor 2 0.373 0.196
  Low expression levels432 515
  High expression levels178 194
Multidrug resistance protein 1 0.338 0.661
  Low expression levels423 496
  High expression levels239 278

Table III.

Multivariate analysis of progression-free survival and overall survival in patients with esophageal squamous cell carcinoma.

Table III.

Multivariate analysis of progression-free survival and overall survival in patients with esophageal squamous cell carcinoma.

Progression-free survivalOverall survival


FactorsHazard ratio95% CIP-valueHazard ratio95% CIP-value
Gender 0.021 0.051
  MaleRef. Ref.
  Female0.7320.563–0.954 0.7560.567–1.008
Tumor location 0.027 NR
  Upper/middleRef. NR
  Lower1.2351.024–1.489 NRNR
Clinical stage 0.020 0.014
  I+IIRef. Ref.
  III1.5071.069–2.129 1.6401.104–2.435
Lymph node metastasis 0.000 0.000
  N0Ref. Ref.
  N11.1700.826–1.656 1.3420.893–2.015
  N21.5161.021–2.251 2.1811.395–3.409
  N32.2601.463–3.491 1.6401.104–2.435
Differentiation 0.061 0.085
  Intermediate/wellRef. Ref.
  Poor/undifferentiated1.2400.999–1.553 1.2330.972–1.564

[i] CI, confidence interval; Ref., reference; NR, not reported.

Discussion

HER2 is a therapeutic target in several tumors such as breast cancer (2932), and a predictive factor of response to chemotherapy in various solid malignancies (3336). In order to identify improved prognostic indicators for ESCC, the clinicopathological features of patients with ESCC were investigated in the present study. In previous studies, the number of copies of the HER2/neu gene was analyzed by fluorescence or chromogenic in situ hybridization, and the protein expression levels of HER2 were evaluated by IHC (6,7,9,10,12,1619). Previous studies examining the association between the expression levels of HER2 (as determined by IHC) and prognosis in patients with ESCC have reported conflicting results (Table IV). These discrepancies may be due to the following reasons: i) Different quality of the studies; ii) multiple factors that may influence prognosis were not considered in all the studies; iii) different laboratory techniques were employed in different studies, including the use of different antibodies to detect HER2 and MRP1; and iv) small size of the samples used in the studies (≤250 patients; Table IV). The association between HER2 expression and prognosis in EC has not been reported thus far.

Table IV.

Previous studies describing the prognostic significance of the expression levels of human epidermal growth factor receptor 2 in ESCC, as determined by IHC or ISH.

Table IV.

Previous studies describing the prognostic significance of the expression levels of human epidermal growth factor receptor 2 in ESCC, as determined by IHC or ISH.

First author, year (reference)Type of cancerPrognostic effectSample size (no. of patients)Method
Hardwick, 1997 (19)ESCC, ACNo effect205IHC
Friess, 1999 (12)ESCC, ACNo effect  39IHC
Mimura, 2005 (9)ESCCUnfavorable  66IHC, ISH
Reichelt, 2007 (10)ESCC, ACNo effect251IHC, ISH
Sato-Kuwabara, 2009 (6)ESCCUnfavorable188IHC, ISH
Stoecklein, 2008 (37)ESCC, ACNo effect101ISH
Schoppmann, 2010 (11)ESCC, ACNo effect341IHC, ISH
Birner, 2011 (38)ESCC, ACUnfavorable330IHC, ISH
Zhan, 2012 (7)ESCCUnfavorable145IHC, ISH
Kato, 2013 (16)ESCCNo effect245IHC, ISH
Wang, 2013 (39)ESCCUnfavorable  72IHC
Wang, 1999 (18)ESCCNo effect117IHC

[i] ESCC, esophageal squamous cell carcinoma; AC, adenocarcinoma; IHC, immunohistochemistry; ISH, in situ hybridization.

In the present study, a large cohort of 829 patients with ESCC and long follow-up was analyzed, and no correlation was observed between the expression levels of HER2 or MRP1 and the postoperative survival time exhibited by these patients. To the best of our knowledge, the present study is the first large-scale study conducted to evaluate the prognostic role of MRP1 expression in patients with ESCC who had been treated with primary surgery. In the present study, a significant association was observed between survival and clinical stage, lymph node metastasis and poor differentiation in patients with ESCC. However, the present study is affected by certain limitations, including its retrospective and single-hospital nature. Thus, multicenter and prospective studies are required to further validate the results of the present study. In addition, the protein expression levels of HER2 and MRP1 were solely examined by IHC in the present study, which may not be completely consistent with their gene expression levels.

In summary, the results of the present study indicated that the expression levels of MRP1 and HER2, as determined by IHC analysis, were not associated with survival rate in patients with ESCC. This result indicates that HER2 or MRP1 expression may not serve as informative prognostic biomarkers. Therefore, further studies are required to clarify the mechanism behind the expression of MRP1 and HER2 in patients with ESCC.

Acknowledgements

The present study was supported by the Province Important Technology and Science Program (Special Feature of Major Province Scientific and Technological Program 2011, grant no. 2011C13039-1), and the National Natural Science Foundation of China (Beijing, China) (General Program; grant nos. 81172081 and 81372210).

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January-2016
Volume 11 Issue 1

Print ISSN: 1792-1074
Online ISSN:1792-1082

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Copy and paste a formatted citation
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Spandidos Publications style
Chen Y, Zhu SM, Xu XL, Zhao A and Hu JL: Expression levels of HER2 and MRP1 are not prognostic factors of long‑term survival in 829 patients with esophageal squamous cell carcinoma. Oncol Lett 11: 745-752, 2016.
APA
Chen, Y., Zhu, S., Xu, X., Zhao, A., & Hu, J. (2016). Expression levels of HER2 and MRP1 are not prognostic factors of long‑term survival in 829 patients with esophageal squamous cell carcinoma. Oncology Letters, 11, 745-752. https://doi.org/10.3892/ol.2015.3975
MLA
Chen, Y., Zhu, S., Xu, X., Zhao, A., Hu, J."Expression levels of HER2 and MRP1 are not prognostic factors of long‑term survival in 829 patients with esophageal squamous cell carcinoma". Oncology Letters 11.1 (2016): 745-752.
Chicago
Chen, Y., Zhu, S., Xu, X., Zhao, A., Hu, J."Expression levels of HER2 and MRP1 are not prognostic factors of long‑term survival in 829 patients with esophageal squamous cell carcinoma". Oncology Letters 11, no. 1 (2016): 745-752. https://doi.org/10.3892/ol.2015.3975