Skip to content

Advertisement

Open Access

Outcome and Human Epithelial Growth Factor Receptor (HER) 1-4 status in invasive breast carcinomas with proliferation indices evaluated using bromodeoxyuridine (BrdU) labelling

  • Sian M Tovey1,
  • Caroline J Witton1,
  • John MS Bartlett1Email author,
  • Peter D Stanton1,
  • Jonathan R Reeves1 and
  • Timothy G Cooke1
Breast Cancer Research20046:R246

https://doi.org/10.1186/bcr783

Received: 27 November 2003

Accepted: 04 March 2004

Published: 04 March 2004

Abstract

Background

We have shown previously that whilst overexpression of HER1, 2 and 3 is associated with poor prognosis in breast cancer, HER4 is associated with a good prognosis. Cell proliferation is a key component of aggressive cancers and is driven by growth factors. In this study bromodeoxyuridine-derived proliferation indices are correlated with clinical outcome and HER1-4 status to further clarify the differing roles for the HER family at a biological level.

Patients and Methods

78 invasive breast cancers had BrdU in vivo labelling to determine the labelling index (BLI) and the potential tumour doubling time (T pot ). Long term clinical follow up was available for these patients. Using immunohistochemistry we established the HER1-4 status in 55 patients from the BrdU cohort.

Results

We demonstrate a significant correlation between high BLI values and breast cancer specific death (p = 0.0174). Low T pot times were also significantly correlated with breast cancer specific death (p = 0.0258). However BLI did not independently predict survival in Cox's multiple regression analysis when combined with other prognostic factors such as size, grade and nodal status.

Tumours found to be positive for HER 1, 2 or 3 had significantly (p = 0.041) higher labelling indices, with HER1 also showing significantly higher indices when considered independently (p = 0.024). Conversely HER4 positivity significantly correlated (p = 0.013) with low BLI values in line with previous data associating this receptor with good prognosis tumours.

Conclusions

These results support the hypothesis that HER1-3 are associated with driving tumour proliferation whilst HER4 is involved in a non-proliferative or even protective role.

Keywords

breast cancerbromodeoxyuridineHER1HER2HER3HER4

Introduction

High rates of cellular proliferation are a key component of aggressive breast cancers. Markers of proliferation, such as Ki67, are widely used to identify cancers with high proliferative indices and have the potential to alter treatment rationale [13]. In addition, determining cellular proliferation rates provides an insight into the intrinsic biology of a tumour, indicating the degree of growth stimulation which is contributing to increasing tumour size. The Human Epithelial Growth Factor Receptor (HER) family of receptor tyrosine kinases form part of a complex signal cascade modulating cell proliferation, survival, adhesion, migration and differentiation. The family is comprised of 4 homologous receptors HER1 (EGFR/ErbB1), HER2 (ErbB2/neu), HER3 (ErbB3) and HER4 (ErbB4) [4]. Over-expression of all 4 receptors has been observed in breast cancer [58]. We have recently demonstrated that patients with overexpression of HER1-3 exhibit markedly reduced survival whilst patients with overexpression of HER4 demonstrate increased survival when compared with patients not expressing high levels of any of these receptors [9]. There is evidence, within the literature, that suggests that HER4 is less able to recruit proliferative (RAS/RAF) signal transduction pathways than other HER family members [10, 4]. Therefore, we have postulated that the apparent protective effect of HER4 may be reflected by lower proliferative indices, whilst cases with higher expression of HER1-3 would demonstrate higher proliferative indices.

HER1 and HER2 are both linked to poor prognostic factors in breast cancer [1114, 8]. Conflicting evidence is available on the prognostic significance of HER3 with some studies demonstrating a relationship between HER3 and some markers of poor prognosis [9, 15, 16]. However others have shown HER3 overexpression is consistent with a good prognostic outlook [17, 18]. HER4 has more consistently been linked to good prognostic factors and a longer disease free interval [19, 20, 9]. We have therefore studied HER1-4 expression in a cohort of patients in whom we have previously performed BrdU labelling to determine tumour proliferative indices and potential tumour doubling times [21] in order to further investigate the biological significance of HER1-4 overexpression with respect to cellular proliferation.

Materials and methods

Patients

89 patients who had a breast cancer of more than 2 cm in diameter were recruited in the original study between 1989–1992. This size criteria was used to ensure that adequate tissue was available for analysis once diagnostic needs had been met. Only postmenopausal patients were entered in view of the unknown embryotoxicity of bromodeoxyuridine. The relevant ethics committees gave approval. Patients who had either breast conservation or mastectomy were included as were those having adjuvant radiotherapy, chemotherapy or tamoxifen as part protocols at that time. Follow up status was obtained by review of patients records with further clarification from data held by the 'Scottish Cancer Intelligence Unit' when there was any doubt over the cause of death. Calculation of BLI was possible in 84 patients. 4 were lost to follow-up and 2 patients were excluded from survival analysis because they had metastasis at the time of diagnosis. 2 patients had bilateral tumours; in these cases the tumour with the highest BLI value was included. Thus there are 78 cases in whom BLI and follow up were available with calculation of T pot present for 55 of them. Material for evaluation of HER1-4 status was available for 55 of the labelled cases.

Bromodeoxyuridine labelling

200 mg of BrdU was administered as an intravenous bolus 4–10 hours prior to surgery. Tumour sample specimens were subjected to flow cytometric analysis and the subsequent calculation of BLI and T pot values has been described previously [21]. The BLI (BrdU labelling index) is presented as a percentage of tumour cells labelling with BrdU (i.e. within the DNA synthetic "S" phase of the cell cycle during exposure to BrdU). The tumour potential doubling time (T pot ) is a measure of the minimum time to doubling of tumour size based on calculation of the length of S phase (Ts) and is expressed in days.

HER 1-4

HER 1-4 status was determined in 55 patients by immunohistochemistry with specific antibodies as described by Witton et al [9] previously. Scoring of membrane staining was performed with excellent agreement between observers (inter-class correlation coefficient ICCC = 0.892).

Statistics

All statistical analysis was performed using the SPSS statistical package (version 9.0.0). Kaplan-Meier life-table analysis was undertaken with log-rank testing of differences in breast cancer-related survival (end-point breast cancer specific death). BLI values ≥ 75th percentile were stratified as 'high' values and Tpot values ≤ 25th percentile were classified as 'low' values for the purpose of survival calculations. These cut-offs were used to identify the relevant 'high risk' populations with regard to their proliferation indices. Multivariate analysis using Cox's multiple regression analysis was performed with the inclusion of known prognostic values such as grade, nodal status, and tumour size. Mann-Whitney test using mean ranks was used to evaluate any correlation between BLI values and HER 1-4 status.

Results

Patients

The median age of patients (n = 78) included in the analysis was 64.6 years. Median follow up available was 6.6 years (range 0.1–13 years). There were 35 breast cancer specific deaths and a further 15 deaths from unrelated causes (mainly cardiac/lung disease with 4 deaths from other cancers). There were 69 ductal tumours, 4 lobular tumours and 5 other or non-specified type. There were 44 ER positive and 30 ER negative cases (4 unknown). The mean size of the tumours is 32.1+/- 20.9 S.D. mm (median 27 mm with interquartile range 20–40 mm). The nodal status was known on 74 patients, with 40 having no nodal involvement, 23 with 1–3 nodes and 11 having over 3 nodes involved (Table 1). 44 patients received a mastectomy and 34 patients had a wide local excision. For the patients with known adjuvant treatment details 93% (69/74) received tamoxifen and only 4% (3/71) received chemotherapy.
Table 1

Tumour size, grade, nodal and ER status of cohort

Parameter

 

n

Tumour size

T1

31

 

T2

39

 

T3

7

 

unknown

1

B+R Grade

1

14

 

2

26

 

3

36

 

unknown

2

Nodal status

negative

40

 

1–3 nodes

23

 

3+ nodes

11

 

unknown

4

ER status

positive

44

 

negative

30

 

unknown

4

BLI and Tpot

The mean BLI value is 4.0 % +/- 3.1 S.D. with the median at 3.2% (interquartile range 1.3–6.4 %). The mean T pot value is 28.3 days +/- 29.3 S.D. with the median at 14.6 days (interquartile range 8.0–37.5 days). BLI and T pot are inversely related in a non-linear fashion with a Spearman rank correlation coefficient of -0.938 (at 0.01 significance level). For this reason and because of the smaller numbers in the T pot group; regression analysis and correlations with the HER group were performed using BLI only.

HER 1-4

HER overexpression was defined as described by Witton et al [9]. Thirteen percent (7/55) of patients were HER1 positive, 19% (10/54) HER2 positive, 20% (10/51) HER3 positive and 11% (6/54) HER4 positive (Table 2). Eighteen (48%) patients were positive for HER1, 2 and or 3 (HER1-3 positive).
Table 2

Relationship between BLI values and HER 1-4 status. *p-values from Mann-Whitney test

HER

Status

n

Median

Mean rank

P

HER1

Positive

7

6.3

40.71

0.024

 

Negative

48

2.5

26.15

 

HER2

Positive

10

4.2

33.05

0.216

 

Negative

44

2.95

26.24

 

HER3

Positive

10

5.25

30.25

0.313

 

Negative

41

3.1

24.96

 

HER4

Positive

6

1.05

12.83

0.013

 

Negative

48

3.25

29.33

 

HER1-3

Positive

18

4.4

34.33

0.041

 

Negative

37

2.5

24.92

 

HER1 positivity was significantly correlated with increased BLI values (p = 0.024); median BLI values for HER1 overexpressing tumours were 2.5 fold higher than for HER1 negative cases. BLI values for HER2 & HER3 positive tumours were 42% and 69% higher than tumours not expressing these proteins at high levels. Neither value reached significance levels (p = 0.216 and p = 0.313). However when considering patients positive for one or more of HER1, HER2 or HER3 (n = 18) this group had significantly higher BLI values (p = 0.041) than tumours which did not express these proteins.

Conversely, tumours with high HER4 expression showed BLI values significantly lower than non HER4 expressing cases (p = 0.013) with a median reduction in BLI of 65%.

Survival

Patients with higher BLI values (≥ 75th percentile, n = 20) demonstrated a significantly poorer prognosis in terms of survival (10 yr survival 35%) from breast cancer when compared to patients with values < 75th percentile (n = 58, 10 yr survival 60%) (p = 0.0174; log-rank test, Figure 1).
Figure 1
Figure 1

Survival curves (Kaplan-Meier) for BLI. Cumulative survival differences between patients whose tumours had high BLI values (≥ 75th percentile ie 6.4%) and low BLI values (<75th percentile). p-values represent log-rank differences in cumulative survival between the two groups.

Patients with low T pot times (≤ 25th percentile, n = 14) had significantly reduced survival (10 yr survival 29%) compared to patients with T pot times > 25th percentile (n = 41, 10 yr survival 58%, p = 0.0258: log-rank test, Figure 2). Further stratification of BLI and T pot into other quartile groups did not show improved distinction in terms of survival (Data not shown).
Figure 2
Figure 2

Survival curves (Kaplan-Meier) for T pot . Cumulative survival differences between patients whose tumours had low T pot values (≤ 25th percentile i.e 8.0 days) or high T pot values (> 25th percentile). p-values represent log-rank differences in cumulative survival between the two groups.

When BLI and HER status were included in Cox's multiple regression analysis along known prognostic variables (Table 3); size and HER 1-3 status were the only independent predictors of survival.
Table 3

Results of Cox's multivariate regresssion analysis for BLI, HER status and known prognostic variables

Variables (n = 48)

p value

Grade

0.155

Size

0.008

Nodal status

0.283

ER status

0.197

BLI

0.052

HER1-3 status

0.003

HER4 status

0.985

Discussion

Studies of tumour labelling index have significant correlations between high proliferation indices and poor outcome [22, 23] although this is not always the case in the context of a multivariate analysis [24, 25]. More recently the proliferation marker Ki67, a nuclear antigen expressed in the G1, S, G2 and M cell phases but not in G0 [26], has been used as a proliferation marker. These methods provide "static" information about the cell cycle in a single point in time, but do not give any information about the rate of progress of the cells through the cycle. Providing dynamic information about the rate of cell cycling may be a more accurate reflection of tumour growth as it allows estimation of parameters such as the potential doubling time. Using flow cytometry and in vivo labelling with the thymidine analogue 5-bromo-2-prime-deoxyuridine (BrdU) it is possible to obtain the labelling index for a tumour (BLI) as well as the potential doubling time of a tumour (T pot ) [27, 28].

We have demonstrated that tumours with either high BLI values or low T pot times have significantly poorer breast cancer specific survival rates. However along with other known prognostic factors BLI was not shown to be an independent prognostic factor in multivariate analysis. This may reflect the small size of the current study, rather than any failure of the method itself, since stage, grade and ER status were also not significant indices of survival in this study. Cutress et al [29] followed-up 75 patients with invasive breast cancer but did not show any significant correlation between proliferation data and outcome measures. A larger study of 129 patients demonstrated a significant correlation between low proliferation indices and survival which persisted in multivariate analysis when known prognostic factors such as node status, age and size of the tumour were included [3].

Tumour growth, which we have sought to measure by calculating T pot , is a balance between cell growth and cell loss and is therefore impacted by factors including oxygenation, apoptosis etc. BrdU labelling does not provide any information about cell loss, which is now recognised to be a significant factor in determining the actual growth of a tumour. Future measurements, which include an estimate of both proliferation and cell loss, may provide more accurate prognostic indices. The use of molecular profiling to identify tumours with differing proliferative and apoptotic signatures may provide valuable information in the future [30].

The use of proliferation indices has however provided us with a method of clarifying the varying effects of the HER4 family at a biological level. Our study demonstrates a significant correlation between high BLI values and HER1 positivity. This is in keeping with previous published results [31]. It is also consistent with other studies using the proliferation marker Ki67 [32]. Interestingly HER1 expression in bladder cancer is also associated with high BrdU indices [33]. We demonstrate a non-significant trend for HER2 positive tumours to have a higher BLI. This is consistent with previously published results by ourselves and others [21, 34]. However there is evidence of a significant correlation between Ki67 and HER2 expression [35, 36].

There is no previous evidence published examining the relationship between HER3, HER4 and BLI. However one study using Ki-67 showed a significant relationship between HER3 and HER4 positivity and decreasing Ki-67 levels [19], arguing that neither of these receptors are involved in directing proliferation. In terms of HER3 in this study we show a non significant trend towards higher BLI values. In addition when tumours positive for one or more of HER 1-3 are taken as a group they show significantly higher proliferation rates. This is in contrast to the findings demonstrated using Ki67 [19] but is more in keeping with studies which have identified a poor prognostic role for HER3 [9, 16]

We demonstrate a significant inverse correlation between HER4 positivity and BLI values. This suggests that HER4 expression in breast cancer may be involved in an anti-proliferative role. Although a proliferative role for HER4 (in keeping with the other HER family members) has been suggested [37, 38] there is other evidence to the contrary. Our previous results suggest that HER4 is very rarely co-expressed with other HER receptors [9]. Data from cell lines has shown that activation of HER4 receptor homodimers results in a weak biological response in comparison to other receptor combinations [10]. Other cell line work has shown that HER4 is necessary to mediate the anti-proliferative and differentiation responses elicited by neuregulin [39]. Indeed in normal breast tissue HER4 appears to play a critical role in the late differentiation of mammary gland function [40]. Thus this evidence appears to support the association HER4 has with improved breast cancer survival times [9]. Some of the conflicting evidence may be explained by the various isoforms of HER4 [41] or because of the inherent difficulty of separating HER4 responses from those of the other family members.

Conclusions

We have provided a biological correlate to substantiate the deleterious effect of HER 1-3 and the protective role for HER4. This possibility of differing roles within the HER4 family in driving proliferation has an implication in the choice of future anti-HER treatment options. Currently the HER2 monoclonal antibody Herceptin (trastzumab) is being used successfully to treat patients with strongly HER2 positive metastatic breast cancer [42]. Our results suggest that the use of pan-HER inhibitors may not be advised in tumours that are positive for HER4 and that more individually directed therapies are needed.

Abbreviations

HER: 

human epithelial growth factor receptor

BrdU: 

bromodeoxyuridine

BLI: 

labelling index

T pot

potential tumour doubling time

ER: 

oestrogen receptor

Declarations

Authors’ Affiliations

(1)
Endocrine Cancer Group, Division of Cancer Sciences and Molecular Biology, University Department of Surgery, Glasgow, UK

References

  1. Amadori D, Silvestrini R: Prognostic and predictive value of thymidine labelling index in breast cancer. Breast Cancer Res Treat. 1998, 51: 267-281. 10.1023/A:1006140629766.View ArticlePubMedGoogle Scholar
  2. Rew DA, Wilson GD: Cell production rates in human tissues and tumours and their significance. Part 1: an introduction to the techniques of measurement and their limitations. Eur J Surg Oncol. 2000, 26: 227-238. 10.1053/ejso.1999.0781.View ArticlePubMedGoogle Scholar
  3. Goodson WH, Moore DH, Ljung BM, Chew K, Mayall B, Smith HS, Waldman FM: The prognostic value of proliferation indices: a study with in vivo bromodeoxyuridine and Ki-67. Breast Cancer Res Treat. 2000, 59: 113-123. 10.1023/A:1006344010050.View ArticlePubMedGoogle Scholar
  4. Yarden Y, Sliwkowski MX: Untangling the ErbB signalling network. Nat Rev Mol Cell Biol. 2001, 2: 127-137. 10.1038/35052073.View ArticlePubMedGoogle Scholar
  5. Lemoine NR, Barnes DM, Hollywood DP, Hughes CM, Smith P, Dublin E, Prigent SA, Gullick WJ, Hurst HC: Expression of the ERBB3 gene product in breast cancer. Br J Cancer. 1992, 66: 1116-1121.View ArticlePubMedPubMed CentralGoogle Scholar
  6. Sainsbury JR, Farndon JR, Sherbet GV, Harris AL: Epidermal-growth-factor receptors and oestrogen receptors in human breast cancer. Lancet. 1985, 1: 364-366. 10.1016/S0140-6736(85)91385-6.View ArticlePubMedGoogle Scholar
  7. Suo Z, Risberg B, Kalsson MG, Willman K, Tierens A, Skovlund E, Nesland JM: EGFR family expression in breast carcinomas. c-erbB-2 and c-erbB-4 receptors have different effects on survival. J Pathol. 2002, 196: 17-25. 10.1002/path.1003.View ArticlePubMedGoogle Scholar
  8. Slamon DJ, Clark GM, Wong SG, Levin WJ, Ullrich A, McGuire WL: Human breast cancer: correlation of relapse and survival with amplification of the HER-2/neu oncogene. Science. 1987, 235: 177-182.View ArticlePubMedGoogle Scholar
  9. Witton CJ, Reeves JR, Going JJ, Cooke TG, Bartlett JM: Expression of the HER1-4 family of receptor tyrosine kinases in breast cancer. J Pathol. 2003, 200: 290-297. 10.1002/path.1370.View ArticlePubMedGoogle Scholar
  10. Alroy I, Yarden Y: The ErbB signaling network in embryogenesis and oncogenesis: signal diversification through combinatorial ligand-receptor interactions. FEBS Lett. 1997, 410: 83-86. 10.1016/S0014-5793(97)00412-2.View ArticlePubMedGoogle Scholar
  11. Klijn JG, Berns PM, Schmitz PI, Foekens JA: The clinical significance of epidermal growth factor receptor (EGF-R) in human breast cancer: a review on 5232 patients. Endocr Rev. 1992, 13: 3-17. 10.1210/er.13.1.3.PubMedGoogle Scholar
  12. Ross JS, Fletcher JA: The HER-2/neu oncogene in breast cancer: prognostic factor, predictive factor, and target for therapy. Stem Cells. 1998, 16: 413-428.View ArticlePubMedGoogle Scholar
  13. Cooke T, Reeves J, Lannigan A, Stanton P: The value of the human epidermal growth factor receptor-2 (HER2) as a prognostic marker. Eur J Cancer. 2001, 37 (Suppl 1): 3-10.View ArticlePubMedGoogle Scholar
  14. Sainsbury JR, Farndon JR, Needham GK, Malcolm AJ, Harris AL: Epidermal-growth-factor receptor status as predictor of early recurrence of and death from breast cancer. Lancet. 1987, 1: 1398-1402.PubMedGoogle Scholar
  15. Naidu R, Yadav M, Nair S, Kutty MK: Expression of c-erbB3 protein in primary breast carcinomas. Br J Cancer. 1998, 78: 1385-1390.View ArticlePubMedPubMed CentralGoogle Scholar
  16. Travis A, Pinder SE, Robertson JF, Bell JA, Wencyk P, Gullick WJ, Nicholson RI, Poller DN, Blamey RW, Elston CW, Ellis IO: C-erbB-3 in human breast carcinoma: expression and relation to prognosis and established prognostic indicators. Br J Cancer. 1996, 74: 229-233.View ArticlePubMedPubMed CentralGoogle Scholar
  17. Pawlowski V, Revillion F, Hebbar M, Hornez L, Peyrat JP: Prognostic value of the type I growth factor receptors in a large series of human primary breast cancers quantified with a real-time reverse transcription-polymerase chain reaction assay. Clin Cancer Res. 2000, 6: 4217-4225.PubMedGoogle Scholar
  18. Quinn CM, Ostrowski JL, Lane SA, Loney DP, Teasdale J, Benson FA: c-erbB-3 protein expression in human breast cancer: comparison with other tumour variables and survival. Histopathology. 1994, 25: 247-252.View ArticlePubMedGoogle Scholar
  19. Knowlden JM, Gee JM, Seery LT, Farrow L, Gullick WJ, Ellis IO, Blamey RW, Robertson JF, Nicholson RI: c-erbB3 and c-erbB4 expression is a feature of the endocrine responsive phenotype in clinical breast cancer. Oncogene. 1998, 17: 1949-1957. 10.1038/sj.onc.1202107.View ArticlePubMedGoogle Scholar
  20. Suo Z, Risberg B, Kalsson MG, Willman K, Tierens A, Skovlund E, Nesland JM: EGFR family expression in breast carcinomas. c-erbB-2 and c-erbB-4 receptors have different effects on survival. J Pathol. 2002, 196: 17-25. 10.1002/path.1003.View ArticlePubMedGoogle Scholar
  21. Stanton PD, Cooke TG, Forster G, Smith D, Going JJ: Cell kinetics in vivo of human breast cancer. Br J Surg. 1996, 83: 98-102.View ArticlePubMedGoogle Scholar
  22. Frierson HF: Ploidy analysis and S-phase fraction determination by flow cytometry of invasive adenocarcinomas of the breast. Am J Surg Pathol. 1991, 15: 358-367.View ArticlePubMedGoogle Scholar
  23. Tubiana M, Pejovic MH, Chavaudra N, Contesso G, Malaise EP: The long-term prognostic significance of the thymidine labelling index in breast cancer. Int J Cancer. 1984, 33: 441-445.View ArticlePubMedGoogle Scholar
  24. Cooke TG, Stanton PD, Winstanley J, Murray GD, Croton R, Holt S, George WD: Long-term prognostic significance of thymidine labelling index in primary breast cancer. Eur J Cancer. 1992, 28: 424-426.View ArticlePubMedGoogle Scholar
  25. Stanton PD, Cooke TG, Oakes SJ, Winstanley J, Holt S, George WD, Murray GD: Lack of prognostic significance of DNA ploidy and S phase fraction in breast cancer. Br J Cancer. 1992, 66: 925-929.View ArticlePubMedPubMed CentralGoogle Scholar
  26. Gerdes J, Lemke H, Baisch H, Wacker HH, Schwab U, Stein H: Cell cycle analysis of a cell proliferation-associated human nuclear antigen defined by the monoclonal antibody Ki-67. J Immunol. 1984, 133: 1710-1715.PubMedGoogle Scholar
  27. Begg AC, McNally NJ, Shrieve DC, Karcher H: A method to measure the duration of DNA synthesis and the potential doubling time from a single sample. Cytometry. 1985, 6: 620-626.View ArticlePubMedGoogle Scholar
  28. White RA, Terry NH, Meistrich ML, Calkins DP: Improved method for computing potential doubling time from flow cytometric data. Cytometry. 1990, 11: 314-317.View ArticlePubMedGoogle Scholar
  29. Cutress RI, Mullee MA, Royle GT, Rew DA: Clinical outcome and bromodeoxyuridine-derived proliferation indices in 75 invasive breast carcinomas. Eur J Surg Oncol. 2000, 26: 747-750. 10.1053/ejso.2000.0997.View ArticlePubMedGoogle Scholar
  30. van de Vijver MJ, He YD, van't Veer LJ, Dai H, Hart AA, Voskuil DW, Schreiber GJ, Peterse JL, Roberts C, Marton MJ, Parrish M, Atsma D, Witteveen A, Glas A, Delahaye L, van d V, Bartelink H, Rodenhuis S, Rutgers ET, Friend SH, Bernards R: A gene-expression signature as a predictor of survival in breast cancer. N Engl J Med. 2002, 347: 1999-2009. 10.1056/NEJMoa021967.View ArticlePubMedGoogle Scholar
  31. Robertson KW, Reeves JR, Smith G, Keith WN, Ozanne BW, Cooke TG, Stanton PD: Quantitative estimation of epidermal growth factor receptor and c-erbB-2 in human breast cancer. Cancer Res. 1996, 56: 3823-3830.PubMedGoogle Scholar
  32. Nicholson RI, McClelland RA, Finlay P, Eaton CL, Gullick WJ, Dixon AR, Robertson JF, Ellis IO, Blamey RW: Relationship between EGF-R, c-erbB-2 protein expression and Ki67 immunostaining in breast cancer and hormone sensitivity. Eur J Cancer. 1993, 29A: 1018-1023.View ArticlePubMedGoogle Scholar
  33. Sauter G, Haley J, Chew K, Kerschmann R, Moore D, Carroll P, Moch H, Gudat F, Mihatsch MJ, Waldman F: Epidermal-growth-factor-receptor expression is associated with rapid tumor proliferation in bladder cancer. Int J Cancer. 1994, 57: 508-514.View ArticlePubMedGoogle Scholar
  34. Moriki T, Takahashi T, Kataoka H, Hiroi M, Yamane T, Hara H: Proliferation marker MIB-1 correlates well with proliferative activity evaluated by BrdU in breast cancer: an immunohistochemical study including correlation with PCNA, p53, c-erbB-2 and estrogen receptor status. Pathol Int. 1996, 46: 953-961.View ArticlePubMedGoogle Scholar
  35. Ioachim E, Kamina S, Athanassiadou S, Agnantis NJ: The prognostic significance of epidermal growth factor receptor (EGFR), C-erbB-2, Ki-67 and PCNA expression in breast cancer. Anticancer Res. 1996, 16: 3141-3147.PubMedGoogle Scholar
  36. Dowsett M, Harper-Wynne C, Boeddinghaus I, Salter J, Hills M, Dixon M, Ebbs S, Gui G, Sacks N, Smith I: HER-2 amplification impedes the antiproliferative effects of hormone therapy in estrogen receptor-positive primary breast cancer. Cancer Res. 2001, 61: 8452-8458.PubMedGoogle Scholar
  37. Tang CK, Concepcion XZ, Milan M, Gong X, Montgomery E, Lippman ME: Ribozyme-mediated down-regulation of ErbB-4 in estrogen receptor-positive breast cancer cells inhibits proliferation both in vitro and in vivo. Cancer Res. 1999, 59: 5315-5322.PubMedGoogle Scholar
  38. Wang LM, Kuo A, Alimandi M, Veri MC, Lee CC, Kapoor V, Ellmore N, Chen XH, Pierce JH: ErbB2 expression increases the spectrum and potency of ligand-mediated signal transduction through ErbB4. Proc Natl Acad Sci U S A. 1998, 95: 6809-6814. 10.1073/pnas.95.12.6809.View ArticlePubMedPubMed CentralGoogle Scholar
  39. Sartor CI, Zhou H, Kozlowska E, Guttridge K, Kawata E, Caskey L, Harrelson J, Hynes N, Ethier S, Calvo B, Earp HS: Her4 mediates ligand-dependent antiproliferative and differentiation responses in human breast cancer cells. Mol Cell Biol. 2001, 21: 4265-4275. 10.1128/MCB.21.13.4265-4275.2001.View ArticlePubMedPubMed CentralGoogle Scholar
  40. Jones FE, Welte T, Fu XY, Stern DF: ErbB4 signaling in the mammary gland is required for lobuloalveolar development and Stat5 activation during lactation. J Cell Biol. 1999, 147: 77-88. 10.1083/jcb.147.1.77.View ArticlePubMedPubMed CentralGoogle Scholar
  41. Gullick WJ: c-erbB-4/HER4: friend or foe?. J Pathol. 2003, 200: 279-281. 10.1002/path.1335.View ArticlePubMedGoogle Scholar
  42. Baselga J: Herceptin alone or in combination with chemotherapy in the treatment of HER2-positive metastatic breast cancer: pivotal trials. Oncology. 2001, 61 (Suppl 2): 14-21. 10.1159/000055397.View ArticlePubMedGoogle Scholar

Copyright

© Tovey et al., licensee BioMed Central Ltd. 2004

This article is published under license to BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.

Advertisement