Quantum dot-based immunofluorescent imaging of Ki67 and identification of prognostic value in HER2-positive (non-luminal) breast cancer

Abstract

Background The immunohistochemical assessment of Ki67 antigen (Ki67) is the most widely practiced measurement of breast cancer cell proliferation; however, it has some disadvantages and thus the prognostic value of Ki67 in breast cancer remains controversial. Our previous studies confirmed the advantages of quantum dots-based nanotechnology for quantitative analysis of biomarkers compared with conventional immunohistochemistry (IHC). This study was designed to assess Ki67 by quantum dot-immunohistochemistry (QD-IHC) and investigate the prognostic value of the Ki67 score in human epidermal growth factor receptor 2 (HER2)-positive (non-luminal) breast cancer. Methods Ki67 expression in 108 HER2-positive (non-luminal) breast cancer specimens was detected by IHC and QD-IHC. Two observers assessed the Ki67 score independently and comparisons between the two methods were made. The prognostic value of the Ki67 score for five-year disease-free survival was estimated. Results The same antigen localization, high correlation of staining rates ( r =0.993), and high agreement of measurements (κ=0.874) of Ki67 expression (cutoff: 30%) in breast cancer were found by QD-IHC and conventional IHC. The QD-IHC had a better interobserver agreement for the Ki67 score than conventional IHC ( t =−7.280, P <0.01). High Ki67 expression (cutoff: 30%) was associated with shorter disease-free survival (log-rank test; IHC, P =0.026; QD-IHC, P =0.001), especially in the lymph node-negative subgroups (log-rank test; IHC, P =0.017; QD-IHC, P =0.002). Conclusion QD-IHC imaging of Ki67 was an easier and more accurate method for detecting and assessing Ki67. The Ki67 score was an independent prognosticator in the HER2-positive (non-luminal) breast cancer patients.

Quantum dot-based immunofluorescent imaging and quantitative detection of TOP2A and prognostic value in triple-negative breast cancer

“…[19][20][21] Our previous studies using QD-based molecular pathology for molecular targeted imaging and quantitative detection of cancer cells and molecules were associated with a number of potential advantages over conventional IHC methods, such as superior fluorescent efficiency over organic fluorescent dyes, better signal clarity, higher sensitivity, and more accurate quantitative analyses. [21][22][23][24] However, the use of QD technology for quantifying TOP2A protein expression in TNBC has not yet been investigated.…”

“…This is consistent with previous reports studying other biomarkers using the QDbased nanotechnology. 21,22,24,35,36 Most importantly, the image gained by QD-IIQAS can be spectrally unmixed without the disturbance of background and quantitatively analyzed by computer software to eliminate the bias that may be caused by manual counting in conventional IHC. Given these advantages over conventional methods, QD-IIQAS has the potential for broad clinical application in the future.…”

Quantitative detection of the tumor-associated antigen large external antigen in colorectal cancer tissues and cells using quantum dot probe

“…27,28 From the QD images of LEA detection, fluorescent signals can be clearly observed and LEA localization on the membrane can be distinguished in high resolution, which favors accurate and automated quantitation of the images, and therefore …”

“…24,25 Based on the advantages of QD probes, many researchers have focused on developing QDbased immunohistochemistry (QD-IHC) to investigate the expression levels of biomarkers in tumor tissues, which has generated detection results similar to conventional IHC. [26][27][28] More importantly, QD-IHC is proven to be superior to conventional IHC in many aspects. 29,30 QD-IHC possesses higher sensitivity leading to an increased positive detection rate compared to conventional IHC.…”

Quantum dots for quantitative imaging: from single molecules to tissue

“…There have been many studies validating detection by QDs in IHC (Chen et al 2009; Xu et al 2012; Tabatabaei-Panah et al 2013; Yu et al 2013). The recent key studies that have demonstrated QD-IHC’s statistical and functional advantages over other forms of IHC include work in which QD-IHC was found to have 5% better sensitivity and 10% better specificity over traditional IHC when examining the Tn antigen in breast cancer tissues (Au et al 2014) and demonstrations that QD-IHC detection of the proliferation marker Ki67 was able to more accurately predict 5-year disease free survival in breast cancer patients (Sun et al 2014). Additionally, QD-IHC is amenable to coupling with signal amplifying techniques such as tyramide signal amplification (TSA) to further enhance detection of subtle antigenic signal (Akhtar et al 2007).…”