Prognostic value of circulating tumor cells in primary and metastatic breast cancer

Chemokines in Triple-Negative Breast Cancer Heterogeneity: New Challenges for Clinical Implications

Tumor heterogeneity is a hallmark of cancer and one of the primary causes of resistance to therapies. Triple-negative breast cancer (TNBC), which accounts for 15% to 20% of all breast cancers and is the most aggressive subtype, is very diverse, connected to metastatic potential and response to therapy. It is a very diverse disease at the molecular, pathologic, and clinical levels. TNBC is substantially more likely to recur and has a worse overall survival rate following diagnosis than other breast cancer subtypes. Chemokines, low molecular weight proteins that stimulate chemotaxis, have been shown to control the cues responsible for TNBC heterogeneity. In this review, we have focused on tumor heterogeneity and the role of chemokines in modulating tumor heterogeneity, since this is the most critical issue in treating TNBC. Additionally, we examined numerous cues mediated by chemokine networks that contribute to the heterogeneity of TNBC. Recent developments in our knowledge of the chemokine networks that regulate TNBC heterogeneity may pave the door for developing difficult-to-treat TNBC treatment options.

Circulating tumour cells at baseline and late phase of treatment provide prognostic value in breast cancer

To determine the prognostic value of the timing of circulating breast tumour cell measurement during treatment, peripheral blood from 164 patients with breast disease was collected. Circulating tumour cells (CTCs) were enriched by using immunomagnetic nanospheres (IMNs) and were identified by using immunofluorescent staining. The CTC shows nuclear-positive, EpCAM-positive, CK19-positive, and CD45-negative. Patients with CTC positivity (> 19/7.5 mL blood) had shorter progression-free survival (PFS) and overall survival (OS) than those with negative results (≤ 19/7.5 mL blood) at baseline. Surgery caused an increase in the number and prevalence of CTCs, and the effect disappeared on day 14 after surgery. During adjuvant chemotherapy, CTCs detected before therapy was only correlated with PFS; however, CTCs at the end of adjuvant chemotherapy were correlated with both PFS and OS. The PFS and OS of the CTC-positive group were significantly shorter than those of the CTC-negative group at the end-point follow-up visit. The prognostic value of CTCs at different measurement time points was demonstrated during breast cancer treatment. Surgery and chemotherapy affected the prevalence of CTCs, leading to different prognostic relevance of CTCs at different treatment stages. CTCs detected at baseline or in the late phase of treatment are preferable for prognosis.

Optical sensor revealed abnormal nuclease spatial activity on cancer cell membrane

Nucleases are important enzymes that cleave nucleic acids and play critical roles in DNA repair, immune defense and potentially in cancer invasion. However, their spatial dynamics at subcellular level is much less studied. Here, we developed a surface-tethered nuclease sensor (SNS) which directly converts membrane-bound nuclease (MN) activity to fluorescent signal, therefore, mapping MN activity on cell adhesion sites with high resolution and sensitivity. With SNS, we studied MN activity on the ventral membrane of cancer cells, where MN activity initially occurs in punctate regions and advances in a coral-shaped pattern. In six tested cell-lines, the MN activity levels in cancer cells are significantly higher than those in non-cancer cells. We then tested SNS as a sensitive approach to detect cancer cells at single cell level. Single breast cancer cells were successfully detected from thousands of adherent non-cancer cells and from millions of non-adherent blood cells.

Tumor Heterogeneity in Breast Cancer

Breast cancer is a heterogeneous disease and differs greatly among different patients (intertumor heterogeneity) and even within each individual tumor (intratumor heterogeneity). Clinical and morphologic intertumor heterogeneity is reflected by staging systems and histopathologic classification of breast cancer. Heterogeneity in the expression of established prognostic and predictive biomarkers, hormone receptors, and human epidermal growth factor receptor 2 oncoprotein is the basis for targeted treatment. Molecular classifications are indicators of genetic tumor heterogeneity, which is probed with multigene assays and can lead to improved stratification into low- and high-risk groups for personalized therapy. Intratumor heterogeneity occurs at the morphologic, genomic, transcriptomic, and proteomic levels, creating diagnostic and therapeutic challenges. Understanding the molecular and cellular mechanisms of tumor heterogeneity that are relevant to the development of treatment resistance is a major area of research. Despite the improved knowledge of the complex genetic and phenotypic features underpinning tumor heterogeneity, there has been only limited advancement in diagnostic, prognostic, or predictive strategies for breast cancer. The current guidelines for reporting of biomarkers aim to maximize patient eligibility for targeted therapy, but do not take into account intratumor heterogeneity. The molecular classification of breast cancer is not implemented in routine clinical practice. Additional studies and in-depth analysis are required to understand the clinical significance of rapidly accumulating data. This review highlights inter- and intratumor heterogeneity of breast carcinoma with special emphasis on pathologic findings, and provides insights into the clinical significance of molecular and cellular mechanisms of heterogeneity.

Rapid and Sensitive Detection of Breast Cancer Cells in Patient Blood with Nuclease-Activated Probe Technology

A challenge for circulating tumor cell (CTC)-based diagnostics is the development of simple and inexpensive methods that reliably detect the diverse cells that make up CTCs. CTC-derived nucleases are one category of proteins that could be exploited to meet this challenge. Advantages of nucleases as CTC biomarkers include: (1) their elevated expression in many cancer cells, including cells implicated in metastasis that have undergone epithelial-to-mesenchymal transition; and (2) their enzymatic activity, which can be exploited for signal amplification in detection methods. Here, we describe a diagnostic assay based on quenched fluorescent nucleic acid probes that detect breast cancer CTCs via their nuclease activity. This assay exhibited robust performance in distinguishing breast cancer patients from healthy controls, and it is rapid, inexpensive, and easy to implement in most clinical labs. Given its broad applicability, this technology has the potential to have a substantive impact on the diagnosis and treatment of many cancers.

Fusion gene and splice variant analyses in liquid biopsies of lung cancer patients

Obtaining a biopsy of solid tumors requires invasive procedures that strongly limit patient compliance. In contrast, a blood extraction is safe, can be performed at many time points during the course disease and encourages appropriate therapy modifications, potentially improving the patient's clinical outcome and quality of life. Fusion of the tyrosine kinase genes anaplastic lymphoma kinase (ALK), C-ROS oncogen 1 (ROS 1), rearranged during transfection (RET) and neurotrophic tyrosine kinase 1 (NTRK1) occur in 1-5% of lung adenocarcinomas and constitute therapeutic targets for tyrosine kinase inhibitors. In addition, a MET splicing variant of exon 14, has been reported in 2-4% of lung adenocarcinoma and recent studies suggests that targeted therapies inhibiting MET signaling would be beneficial for patients with this alteration. In this review, we will summarize the new techniques recently developed to detect ALK, RET, ROS and NTRK1 fusions and MET exon 14 splicing variant in liquid biopsy using plasma, serum, circulating tumor cells (CTCs), platelets and exosomes as starting material.

Protein disulfide isomerases in the endoplasmic reticulum promote anchorage-independent growth of breast cancer cells

Metastatic breast cancer cells are exposed to stress of detachment from the extracellular matrix (ECM). Cultured breast cancer cells that survive this stress and are capable of anchorage-independent proliferation form mammospheres. The purpose of this study was to explore a link between mammosphere growth, ECM gene expression, and the protein quality control system in the endoplasmic reticulum (ER). We compared the mRNA and protein levels of ER folding factors in SUM159PT and MCF10DCIS.com breast cancer cells grown as mammospheres versus adherent conditions. Publicly available gene expression data for mammospheres formed by primary breast cancer cells and for circulating tumor cells (CTCs) were analyzed to assess the status of ECM/ER folding factor genes in clinically relevant samples. Knock-down of selected protein disulfide isomerase (PDI) family members was performed to examine their roles in SUM159PT mammosphere growth. We found that cells grown as mammospheres had elevated expression of ECM genes and ER folding quality control genes. CTC gene expression data for an index patient indicated that upregulation of ECM and ER folding factor genes occurred at the time of acquired therapy resistance and disease progression. Knock-down of PDI, ERp44, or ERp57, three members of the PDI family with elevated protein levels in mammospheres, in SUM159PT cells partially inhibited the mammosphere growth. Thus, breast cancer cell survival and growth under detachment conditions require enhanced assistance of the ER protein folding machinery. Targeting ER folding factors, in particular members of the PDI family, may improve the therapeutic outcomes in metastatic breast cancer.

The Clinical Utility of Circulating Tumor Cells in Breast Cancer Patients: Detection by a Quantitative Assay of h-MAM Gene Expression

The aim of this study was to evaluate tumor markers of molecular abnormalities that display tissue specificity, as to detect circulating tumor cells (CTCs) in breast cancer patients. Quantitative real-time RT-PCR was used to determine h-MAM, BCSG1, CK19, and c-erbB2 mRNA levels in peripheral blood (PB) of breast cancer patients. Results were compared with other epithelial cancers (lung or esophagus cancer), benign breast disease, and healthy individuals. We found that h-MAM mRNA was only detectable in the PB of patients with breast cancer (49 of 65, 75.4%), but not in patients with other epithelial cancers, benign breast disease, or healthy individuals. No significant differences in the expression level and positive detection rate of BCSG1, CK19, and c-erbB2 mRNA were observed between breast cancer and other epithelial cancers. Furthermore, the expression level and positive detection rate of h-MAM mRNA in PB were significantly correlated to the breast cancer pathologic stage (p=0.012 and p=0.015, respectively). Chemotherapy, radiotherapy, or total tumor resection (after 7 days of treatment) resulted in a significant decrease in the expression level of h-MAM mRNA in PB compared to the levels prior to the treatment (p<0.001). Importantly, an increase in h-MAM mRNA expression was detected in patients immediately after surgery, as well as 3 days post-surgery. These results indicate that the quantitative analysis of h-MAM mRNA is a useful tool for detecting CTCs in breast cancer patients, and can have a potential diagnostic utility in early micrometastasis, clinical evaluation of cancer treatment efficacy, and post-treatment monitoring of breast cancer patients.

Evaluation of two different analytical methods for circulating tumor cell detection in peripheral blood of patients with primary breast cancer

Background. Evidence is accumulating that circulating tumor cells (CTC) out of peripheral blood can serve as prognostic marker not only in metastatic but also in early breast cancer (BC). Various methods are available to detect CTC. Comparisons between the different techniques, however, are rare. Material and Methods. We evaluate two different methods for CTC enrichment and detection in primary BC patients: the FDA-approved CellSearch System (CSS; Veridex, Warren, USA) and a manual immunocytochemistry (MICC). The cut-off value for positivity was ≥1 CTC. Results. The two different nonoverlapping patient cohorts evaluated with one or the other method were well balanced regarding common clinical parameters. Before adjuvant CHT 21.1% (416 out of 1972) and 20.6% (247 out of 1198) of the patients were CTC-positive, while after CHT 22.5% (359 out of 1598) and 16.6% (177 out of 1066) of the patients were CTC-positive using CSS or MICC, respectively. CTC positivity rate before CHT was thus similar and not significantly different (P = 0.749), while CTC positivity rate immediately after CHT was significantly lower using MICC compared to CSS (P < 0.001). Conclusion. Using CSS or MICC for CTC detection, we found comparable prevalence of CTC before but not after adjuvant CHT.

An automated high-throughput counting method for screening circulating tumor cells in peripheral blood

Enumeration of circulating tumor cells (CTCs) has proved valuable for early detection and prognosis in cancer treatment. This paper describes an automated high-throughput counting method for CTCs based on microfluidics and line-confocal microscopy. Peripheral blood was directly labeled with multiple antibodies, each conjugated with a different fluorophore, pneumatically pumped through a microfluidic channel, and interrogated by a line-confocal microscope. On the basis of the fluorescence signals and labeling schemes, the count of CTCs was automatically reported. Due to the high flow rate, 1 mL of whole blood can be analyzed in less than 30 min. We applied this method in analyzing CTCs from 90 stage IV breast cancer patient samples and performed a side-by-side comparison with the results of the CellSearch assay, which is the only method approved by the U.S. Food and Drug Administration at present for enumeration of CTCs. This method has a recovery rate for cultured breast cancer cells of 94% (n = 9), with an average of 1.2 counts/mL of background level of detected CTCs from healthy donors. It detected CTCs from breast cancer patients ranging from 15 to 3375 counts/7.5 mL. Using this method, we also demonstrate the ability to enumerate CTCs from breast cancer patients that were positive for Her2 or CD44(+)/CD24(-), which is a putative cancer stem cell marker. This automated method can enumerate CTCs from peripheral blood with high throughput and sensitivity. It could potentially benefit the clinical diagnosis and prognosis of cancer.