ELF5 and DOK7 regulation in anti-estrogen treated cells and tumorsReport as inadecuate




ELF5 and DOK7 regulation in anti-estrogen treated cells and tumors - Download this document for free, or read online. Document in PDF available to download.

Cancer Cell International

, 16:8

First Online: 16 February 2016Received: 04 August 2015Accepted: 03 February 2016

Abstract

BackgroundMost women with primary breast cancers that express estrogen receptor alpha ER or ESR1 are treated with endocrine therapies including the anti-estrogen tamoxifen, but resistance to these anti-endocrine therapies often develops. This study characterizes the expression of hormone receptors, and the mRNA and DNA methylation levels of docking protein 7 DOK7, and E74-like factor 5 ELF5, in 21 novel tamoxifen-resistant cell lines and extends the findings to primary and recurrent human breast tumors.

MethodsTwenty-one tamoxifen-selected cell lines were developed through cloning by limiting dilution of an MCF-7 cell culture treated with 1 μM tamoxifen for 6 months. The parent MCF-7 and tamoxifen-selected cell lines were characterized for protein expression of ER, progesterone receptor PR and human epidermal growth factor receptor 2 HER2 using immunohistochemistry IHC. The mRNA levels of ER, DOK7, and ELF5 were assessed using quantitative RT-PCR. Promoter methylation levels of DOK7 and ELF5 were determined by pyrosequencing of bisulfite-modified DNA. The relationship between hormone receptor status and promoter methylation of DOK7 and ELF5 was further examined using available methylation array data Illumina HM450 from a set of paired primary and second breast tumors from 24 women.

ResultsAll 21 of the novel tamoxifen-selected cell lines are ER-positive, and HER2-negative, and 18 of the cell lines are PR-negative while the MCF-7 cells were scored as ER-positive, modestly PR-positive and HER2 negative. Expression of DOK7 and ELF5 is significantly up-regulated in half of the tamoxifen-selected cell lines as compared to the parental MCF-7. In contrast, the previously established ER-negative TMX2-28 cell line has decreased expression of both DOK7 and ELF5 and increased DNA methylation in the transcriptional start site region of these genes. ELF5 methylation was lower in second versus primary tumors in women who received anti-estrogen treatment, in PR-negative versus PR-positive tumors, and in the subset of PR-positive first tumors from the group of women who had second PR-negative tumors as compared to those who had second PR-positive tumors.

ConclusionsThe distinct ELF5 methylation of PR-positive primary tumors from women who had a PR-negative recurrence indicates the possibility of stratification of women for tailored treatment in the early stages of disease.

KeywordsBreast cancer DOK7 ELF5 Estrogen receptor Progesterone receptor Tamoxifen resistance AbbreviationsCpGcytosine-phosphodiester bonded to a Guanine

ELF5E74-like factor 5

ERestrogen receptor

HER2human epidermal growth factor receptor 2

HM450BChuman methylation 450K bead chip

HPRThypoxanthine–guanine phosphoribosyltransferase

IHCimmunohistochemistry

PRprogesterone receptor

qRT-PCRquantitative reverse transcriptase polymerase chain reaction

TSS1500transcriptional start site 1500 region

TSS200transcriptional start site 200 region

Download fulltext PDF



Author: Lily M. Fitzgerald - Eva P. Browne - Kevin D. Christie - Elizabeth C. Punska - Leo O. Simmons - Kristin E. Williams -

Source: https://link.springer.com/article/10.1186/s12935-016-0282-9



DOWNLOAD PDF




Related documents