The correlation study between TOP2A gene expression in circulating tumor cells and chemotherapeutic drug resistance of patients with breast cancer

Abstract

Background: Patients with breast cancer (BC) at advanced stages have poor outcomes because of high rate of recurrence and metastasis. Biomarkers for predicting prognosis remain to be explored. This study aimed to evaluate the relationships between circulating tumor cells (CTCs) and outcomes of BC patients.

Patients and methods: A total of 50 female were enrolled in this study. Their diagnoses were determined by clinical characteristics, image data, and clinical pathology. CTC subtypes and TOP2A gene expression on CTCs were detected by CanPatrol™ technology and triple color in situ RNA hybridization (RNA-ISH), which divided into epithelial CTCs (eCTCs), mesenchymal CTCs (MCTCs), and hybrid CTCs (HCTCs) based on their surface markers. Hormone receptor, including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) expression, was measured by immunohistochemistry (IHC) method before treatment. The risk factors for predicting recurrence and metastasis were calculated by COX risk regression model. The progression-free survival (PFS) of patients was determined using Kaplan-Meier survival curve.

Results: The patients with a large tumor size (≥ 3 cm) and advanced tumor node metastasis (TNM) stages had high total CTCs (TCTCs) (P < 0.05). These patients also had high TOP2A expression level. COX risk regression analysis indicated that TOP2A expression levels in TCTCs, ER + , HER-2 + , and TNM stages were critical risk factors for recurrence and metastasis of patients (P < 0.05). The PFS of patients with ≥ 5 TCTCs, ≥ 3 HCTCs, and positive TOP2A expression in ≥ 3 TCTCs was significantly longer than that in patient with < 5 TCTCs, < 3 HCTCs, and TOP2A expression in < 3 TCTCs (P < 0.05). In contrast, the PFS of patients with positive hormone receptors (ER + , PR + , HER-2 +) also was dramatically lived longer than that in patients with negative hormone receptor expression.

Conclusions: High TCTC, HCTCs, and positive TOP2A gene expression on CTCs were critical biomarkers for predicting outcomes of BC patients. Positive hormone receptor expression in BC patients has significant favor PFS.

Keywords: Breast cancer; Circulating tumor cell; Progression-free survival; RNA in situ hybridization.

Fig. 1

The TOP2A mRNA expression in CTCs. Fluorescence microscope images of different subtypes of CTCs. Red fluorescence: epithelial marker expression signal points; Green fluorescence: mesenchymal marker expression signal points; Purple fluorescence: TOP2A gene expression signal points; Blue fluorescence: DAPI nucleus. A DAPI stain nucleus; B epithelial type CTCs (eCTCs); C mesenchymal type CTCs (MCTCs); D TOP2A-positive CTCs; E hybrid CTCs. CTC, circulating tumor cell; DAPI, 6-diamidino-2-phenylindole

Fig. 2

Survival curve of CTCs and TOP2A in TCTCs. A PFS Comparison between patients with ≥ 5 TCTCs and < 5 TCTCs; B PFS Comparison between patients with ≥ 3HCTCs and < 3 HCTCs; C PFS Comparison between patients with ≥ TOP2A in ≥ 3 TCTCs and < 3 TCTCs; TCTCs total circulating tumor cells, HCTCs hybrid circulating tumor cells, PFS progression-free survival, HR hazard ratio, CI confidence interval

Fig. 3

Survival curve of breast cancer patient with different hormone receptor. A PFS Comparison between patients with ER-positive and ER-negative; B PFS Comparison between patients with PR-positive and PR-negative; C PFS Comparison between patients with HER-2 positive and HER-2 negative. PFS progression-free survival, HR hazard ratio, CI confidence interval