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Lack of epidermal growth factor receptor (EGFR)-activating mutations in triple-negative breast cancer in China

Breast Cancer Research201517:115

https://doi.org/10.1186/s13058-015-0628-6

  • Published:

Keywords

  • Epidermal Growth Factor Receptor
  • Polymerase Chain Reaction Assay
  • Chinese Patient
  • EGFR29 Mutation
  • Archival Tissue

We read with interest the study by Teng and colleagues reporting a high frequency (11.4 %) of epidermal growth factor receptor (EGFR)-activating mutations in triple-negative breast cancer (TNBC) in a Singapore cohort [1]. In a separate study, EGFR-activating mutations were detected in 7.7 % (1 out of 13) of Chinese basal-like breast cancers [2]. Interestingly, this frequency ranged from 0 to 3 % of other Asian and Caucasian patients [3, 4]. These results indicate that the frequency of these mutations may vary according to geographic and ethnic differences, as reported in non-small cell lung cancer, and these mutations appear to be limited mostly to Chinese patients with TNBC. In this study, in-depth characterization of these mutations in Chinese TNBC was attempted on retrospective archival tissues.

Fifty freshly frozen specimens of TNBC from patients without neoadjuvant chemotherapy were randomly selected from Zhejiang Cancer Hospital, China, from 2010 to 2011. The specimens were confirmed to be estrogen receptor- and progesterone receptor-negative, and less than 1 % of tumor cells showed positive nuclear staining by an immunohistochemistry (IHC) assay. HER-2 negativity was defined as a score of 0 or 1+ by IHC assay or a HER-2/chromosome 17 ratio of less than 2 and fewer than 4 HER-2 copies per nucleus by a fluorescence in situ hybridization assay. Written consent was obtained from all participants. This study was approved by the Research and Ethics Committee of Zhejiang Cancer Hospital.

Twenty-five EGFR-activating mutations (G719S, G719A, G719C, S768I, L858R, and L861Q and 19 mutations of exon 19-Del) were analyzed by an Amplification Refractory Mutation System (ARMS) assay by using an ADx EGFR29 Mutation Kit (Amoy Diagnostics, Xiamen, China). The ARMS assay is able to detect mutations with allele frequencies as low as 1 % [5]. Exons 18, 19, 20, and 21 were amplified by polymerase chain reaction assay, and all fragments were bidirectionally sequenced to screen for other mutations.

None of the EGFR-activating mutations was found by these two assays, but four single-nucleotide polymorphisms (SNPs) were identified by the sequencing assay (Table 1).
Table 1

Polymorphisms in exons 18, 19, 20, and 21 of EGFR in 50 triple-negative breast cancers

Exon

Position

Amino acid change

Minor allele frequency (number)

dbSNP

NNSplice

Human Splicing Finder

Score ratio of donor site (SNP versus normal)

Score ratio of acceptor site (SNP versus normal)

Intron 19

c.2283 + 103C > T

-

0.1 (10)

rs17290371

0.48:0.53

-

Creation of an intronic ESE site

20

c.2361G > A

Q787Q

0.18 (9)

rs1050171

0:0.43

-

Probably no impact on splicing

20

c.2457G > A

V819V

0.04 (1)

rs56183713

0.53:0

0.89:0.65

1. Creation of an exonic ESS site

2. Alteration of an exonic ESE site

Intron 20

c.2470-68C > A

-

0.02 (1)

rs530416576

-

-

Creation of an intronic ESE site

EGFR epidermal growth factor receptor, SNP single-nucleotide polymorphism, ESE exonic splicing enhancer, ESS exonic splicing silencer

In silico prediction was performed to investigate the effect of the SNPs on gene splicing by using two programs: NNSplice 0.9 version (http://www.fruitfly.org/seq_tools/splice.html) and Human Splicing Finder (http://www.umd.be/HSF3/). All four SNPs, particularly the c.2457G > A SNP, were predicted to alter splicing by one or both programs.

In summary, none of the well-known EGFR-activating mutations was identified in our cohort. This suggests that TNBCs form a group of cancers with marked heterogeneity. Targetable mutations may be present and clinically helpful in only a limited number of Chinese patients with TNBC.

Notes

Abbreviations

ARMS: 

Amplification Refractory Mutation System

EGFR: 

Epidermal growth factor receptor

IHC: 

Immunohistochemistry

SNP: 

Single-nucleotide polymorphism

TNBC: 

Triple-negative breast cancer

Declarations

Acknowledgments

This study was supported by grants from the Science and Technology Program offered by the Health Bureau of Zhejiang Province, China (grants 2012RCB006 and 2014KYA006) and the Zhejiang Province Traditional Medical Science Fund Project of China (grant 2012ZB019). ARMS assay and sequencing were performed by the Innovation Center China, AstraZeneca Global R&D, Shanghai, China.

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Medical Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China
(2)
Zhejiang Key Laboratory of the Diagnosis & Treatment Technology on Thoracic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China
(3)
Institute of Cancer Research, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China

References

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Copyright

© Cao et al. 2015

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