Flow cytometry correlates with RT-PCR for detection of spiked but not circulating colorectal cancer cells

Evaluation of circulating tumor cells in colorectal cancer using flow cytometry

Objective

We aimed to evaluate the prognostic value of circulating tumor cells (CTCs) and the impact of intraoperative tumor manipulation on CTCs in colorectal cancer (CRC) patients.

Methods

We performed a prospective study on 40 patients with CRC stages I to IV who received curative surgery using the no-touch technique. Flow cytometry was used to identify CTCs in peripheral blood samples (4 mL/sample) collected at two surgical moments: skin incision (T1) and after surgical resection (T2). A threshold of ≥4 CTCs/4 mL blood was established for considering patients CTC positive.

Results

In the univariate analysis, CTC evaluation at T2 was correlated with female sex, vascular invasion, tumor localization in the colon and metastatic lymph nodes. In the multivariate analysis, only female sex and colon cancer maintained statistical significance. At a medium follow-up of 15 months (1–25 months), the mortality rate was 10% (n = 4), with no significant differences between the overall survival of T1 or T2 CTC-positive and CTC-negative patients.

Conclusions

Flow cytometry is a feasible CTC identification technique in CRC, and although surgical manipulation has no influence on CTC numbers, CTCs may serve as a prognostic and predictive factor.

GAS2L1 Is a Potential Biomarker of Circulating Tumor Cells in Pancreatic Cancer

Pancreatic cancer is a malignant disease with high mortality and a dismal prognosis. Circulating tumor cell (CTC) detection and characterization have emerged as essential techniques for early detection, prognostication, and liquid biopsy in many solid malignancies. Unfortunately, due to the low EPCAM expression in pancreatic cancer CTCs, no specific marker is available to identify and isolate this rare cell population. This study analyzed single-cell RNA sequencing profiles of pancreatic CTCs from a genetically engineered mouse model (GEMM) and pancreatic cancer patients. Through dimensionality reduction analysis, murine pancreatic CTCs were grouped into three clusters with different biological functions. CLIC4 and GAS2L1 were shown to be overexpressed in pancreatic CTCs in comparison with peripheral blood mononuclear cells (PBMCs). Further analyses of PBMCs and RNA-sequencing datasets of enriched pancreatic CTCs were used to validate the overexpression of GAS2L1 in pancreatic CTCs. A combinatorial approach using both GAS2L1 and EPCAM expression leads to an increased detection rate of CTCs in PDAC in both GEMM and patient samples. GAS2L1 is thus proposed as a novel biomarker of pancreatic cancer CTCs.

Assessment of circulating tumor cells in peripheral blood using flow cytometry in patients with surgery for colorectal cancer – review

Introduction: Colorectal cancer (CRC) is the third most common neoplasia in the world. Circulating tumor cells (CTC) have a prognostic value and can be useful in monitoring solid neoplasia. Only one method for CTC identification has received the approval and this is the CellSearch® system based on the immunomagnetic separation. Multiple markers are used in CTC identification, as epithelial markers and cytokeratines. CTC identification in peripheral blood is associated with a worse prognostic and reduced free survival in CRC.

Material and methods: We performed a systematic search in PubMed database for articles that reports the circulating tumor cells in CRC until July 2019. We selected studies in English and French and the main words used for search were ‘circulating tumor cells’, ‘colorectal cancer’, ‘colon cancer’, ‘rectal cancer’, ‘flow cytometry’, ‘peripheral blood’. We included studies with more than 10 patients, where samples were collected from the blood in relation with surgery and flow cytometry was used as analyzing technique.

Results: We included 7 studies in final analysis, that showed in flow cytometry analysis a cut-off value of CTC that can vary from 2-4 CTC/ 7.5 ml peripheral blood with a sensitivity of 50.8% and specificity of 95%. Patients with positive CTC were associated with higher T stage and positive lymph nodes, with a worse overall survival (OS) and disease free survival (DFS) comparing with negative patients.

Conclusion: CTC are considered to be a prognostic factor who needs more validation studies in order to be included in the clinical practice.

Simultaneous isolation and detection of single breast cancer cells using surface-enhanced Raman spectroscopy

Nowadays, cancer is one of the most dangerous and deadly disease all around the world. Cancer that is diagnosed at early stages is more likely to be treated successfully. Treatment of progressed cancer is very difficult, and generally surviving rates are much lower. Therefore, much research has been focused on developing non-invasive methods for detection of cancer and monitoring of its progress. Within this contribution, we present a novel strategy for selective isolation and detection of breast cancer cell lines (MCF-7 and BT-20) based on surface enhanced Raman scattering (SERS). A simplified protocol based on cell-aptamer interaction has been developed in which core-shell (Au@Fe₃O₄) nanoparticles (CSNs) were functionalized with a mucin 1 (MUC1) specific aptamer (Apt1) to capture cells through the interaction between Apt1 and overexpressed protein (MUC1) on the surface of the tumor cells. Meanwhile, a SERS nano-tag, synthesized by the conjugation of Apt1 to the surface of BSA coated and with 4-mercaptopyridine (4-Mpy) functionalized gold nanoparticles, was used to detect the isolated cells. As a conclusion, the proposed strategy can be extended to isolate and detect cells more precisely based on the detection of different kinds of biomarkers on the surface of cancer cells, simultaneously.

Diversity of assessing circulating tumor cells (CTCs) emphasizes need for standardization: a CTC Guide to design and report trials

Hematogenous spreading of tumor cells from primary tumors is a crucial step in the cascade to metastasis, the latter being the most limiting factor for patients' survival prognosis. Therefore, circulating tumor cells (CTCs) have become a field of intensive research. However, the process of isolation and identification of CTCs lacks standardization. This article presents an overview of 71 CTC studies reported in PUBMED since 2000 and focusing on colorectal cancer. These studies are evaluated regarding standardization of CTC isolation and identification, marker proteins used, study population and blood sample quality management, clinical performance, and quality measures. Overall, standardization of CTC assessment seems insufficient. Thus, comparability of CTC studies is hampered and results should be interpreted carefully. We here propose a standardized CTC guideline (CTC Guide) to prospectively design and report studies/trials in a harmonized form. Despite the current interstudy heterogeneity, the data indicate that CTC detection is of clinical relevance and CTCs should be considered as a surrogate prognostic marker. Many studies indicate the high potential for CTCs as prognostic markers, e.g., in colorectal cancer treatment. However, standardized, large-scale multicenter validation studies are still needed to pave the way for clinical implementation of CTC detection that could ameliorate individualized medicine regimes.

Flow cytometric analysis of CD133- and EpCAM-positive cells in the peripheral blood of patients with lung cancer

Lung tumors are characterized by their high metastatic potential, which is the main cause of therapeutic failure. However, the exact cellular origin of metastasis remains unknown. Since the introduction of the cancer stem cell theory, lung cancer stem cells (LCSCs) have been thought to represent metastasis-founding cells. The current study aimed to evaluate whether LCSCs could be found in the circulation. Expression of the stem cell markers CD133 and EpCAM was confirmed in tumor and normal lung tissue by flow cytometry. Then, this technique was further used to investigate the expression of CD133 and EpCAM in the peripheral blood of 41 patients with primary lung cancer. Putative LCSCs (CD133?EpCAM?) were present in 6/7 tumor samples, and CD133?EpCAM? cells were identified in the blood samples of 15 patients at a median level of 40/ml of blood. EpCAM? cells were detected in 60 % of the patients, and the number of these cells was higher in patients with adenocarcinoma than patients with squamous cell carcinoma and was also higher in patients with less advanced disease. Moreover, the frequency of this subpopulation significantly correlated with the circulating level of SSEA-4? cells. Additionally, CD133?EpCAM- cells were found in 87 % of the patients, and the numbers of these cells were significantly higher in patients with distant metastases and correlated with disease stage. This study confirmed the presence of an LCSC subpopulation with a CD133?EpCAM? phenotype in the tumors and blood of patients with lung cancer, and these results suggest an important role for CD133 and EpCAM in lung cancer progression and their potential application as novel biomarkers of the disease.

Development of a quantum-dot-labelled magnetic immunoassay method for circulating colorectal cancer cell detection

AIM: To detect of colorectal cancer (CRC) circulating tumour cells (CTCs) surface antigens, we present an assay incorporating cadmium selenide quantum dots (QDs) in these paper.

METHODS: The principle of the assay is the immunomagnetic separation of CTCs from body fluids in conjunction with QDs, using specific antibody biomarkers: epithelial cell adhesion molecule antibody, and monoclonal cytokeratin 19 antibody. The detection signal was acquired from the fluorescence signal of QDs. For the evaluation of the performance, the method under study was used to isolate the human colon adenocarcinoma cell line (DLD-1) and CTCs from CRC patients’ peripheral blood.

RESULTS: The minimum detection limit of the assay was defined to 10 DLD-1 CRC cells/mL as fluorescence was measured with a spectrofluorometer. Fluorescence-activated cell sorting analysis and Real Time RT-PCR, they both have also been used to evaluate the performance of the described method. In conclusion, we developed a simple, sensitive, efficient and of lower cost (than the existing ones) method for the detection of CRC CTCs in human samples. We have accomplished these results by using magnetic bead isolation and subsequent QD fluorescence detection.

CONCLUSION: The method described here can be easily adjusted for any other protein target of either the CTC or the host.

Evaluation of laparoscopic resection of colorectal carcinoma from the viewpoint of molecular biology

AIM

Detection of the possible impact of surgical management on the occurrence of minimal residual disease (MRD) in patients with colorectal carcinoma (CRC) in bone marrow samples, portal and peripheral blood samples. Comparison of MRD prevalence in patients with laparoscopic resection of CRC and those with open colorectal resection. Assessment of the potential impact of MRD on the relapse of the disease and overall survival of patients.

MATERIAL AND METHODS

The study included 124 patients with primary CRC without proven distant metastases indicated for elective laparoscopic resection and operated on between September 21, 2006 and December 31, 2008 at the Department of Surgery, Hospital and J.G. Mendel Oncological Centre Novy Jicin. 6 samples were collected from each patient to determine MRD (system venous blood and bone marrow at the beginning of surgery, venous blood from mesenteric bloodstream, system venous blood after the resection, system venous blood and bone marrow 1 month after the surgery). Detection of MRD on the basis of CEA expression was performed by real-time RT-PCR technique. The results were compared with those obtained within the similar research using the same methodology at the 2(nd) Department of Surgery, University Hospital in Olomouc (the group included 230 patients treated with open resection of CRC).

RESULTS

In the group of patients treated with laparoscopic resection, a correlation between positive MRD in the sample of bone marrow collected before the surgery and the stage of the disease was found (p < 0.035). We also recorded the impact of surgical management on MRD occurrence in system venous blood in primary negative patients (p < 0.025). However, in the course of the short period of time we have not found a statistically significant correlation between the finding in patients with stage I-III, and the period prior to the relapse of the disease (p < 0.59). With regard to the results obtained, we can expect a potential direct correlation between a positive MRD finding in system venous blood taken prior to surgery in patients with stage I-III CRC and shorter time of survival (p < 0.075). In the group of patients treated with open resection of CRC, no statistically significant relationship between the stage of the disease and MRD occurrence was found. Incidence of circulating tumour cells (CTC) in the samples of venous blood taken prior to surgery is a prognostically important factor (p < 0.05) from the viewpoint of disease-free survival (DFS). Another prognostically important factor with regard to DFS seems to be the occurrence of disseminated tumour cells (DTC) in the bone marrow taken 1 month after the surgery.

CONCLUSIONS

The data recorded suggest a relationship between MRD finding and the disease prognosis. Collection of samples as well as evaluation of results continue as we strive to include more patients in our study and to obtain more data within 5-10 years of the follow-up. The comparison between the data obtained in the laparoscopic approach and the data obtained in open resection performed from the viewpoint of molecular biology did not show a significant difference in MRD detection in the samples collected after the surgery.

Nucleic acid aptamers for clinical diagnosis: cell detection and molecular imaging

Nucleic acid aptamers have recently attracted significant attention in the field of clinical diagnosis because they have numerous merits, such as high affinity, high specificity, small size, little immunogenicity, stable structures, and ease of synthesis. This review focuses on discussing the potential applications of aptamers in cell detection and molecular imaging. For the ex vivo cell detection, this review discusses the status of five strategies: endogenous nucleic acid analysis, flow cytometry analysis, nanoparticle-based cell sensing, microfluidic cell separation, and histological examination. This review also discusses in vivo molecular and cell imaging by introducing aptamer-based molecular imaging, cell imaging, and integrated imaging and therapy. On the basis of the status of these promising studies, this review summarizes several challenging issues and unmet needs that may require more effort or attention in the future.

Quantitative RT-PCR detection of colorectal tumor cells in peripheral blood--a systematic review

BACKGROUND

Twenty percent to 40% of patients with node-negative colorectal cancer die of metastatic disease. Detection of cancer cell dissemination has been proposed as a tool to select patients at highest risk for recurrence. In this review, we summarize the evidence for detection with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assays of circulating tumor cells (CTCs) in peripheral blood of colorectal cancer patients.

MATERIALS AND METHODS

Pubmed and Embase were systematically searched for all English publications relevant to circulating cancer cells, peripheral blood, quantitative RT-PCR (q-RT-PCR), and colorectal cancer. Cross-references and the "related articles" function were used to broaden the search. Manuscripts reporting on the results of nonquantitative RT-PCR assays were excluded. The study methodology, CTCs detection rates in peripheral blood, and prognostic value were reviewed.

RESULTS

Twelve manuscripts on qRT-PCR were retrieved. Stage dependence was found for detection of CTCs in four of 10 studies. From univariate analysis performed for disease-free survival and overall survival in 4 of 12 studies, there was evidence (P < 0.05) for an effect of the detection of CTCs with qRT-PCR. None of the included trials identified detection of CTCs in peripheral blood as an independent predictor of survival.

CONCLUSION

Quantification of CTCs in peripheral blood holds promise in predicting stage and outcome in colorectal cancer patients. At present, evidence from the literature is too scarce to integrate quantitative RT-PCR assays to detect CTCs into the management of colorectal cancer.

Standardized quantification of circulating peripheral tumor cells from lung and breast cancer

Detection and quantitation of circulating tumor cells from solid epithelial tumors could become a valuable tool for therapy monitoring if the procedure can be standardized. In the present work we assessed the influence of pre-analytical handling, storage and white blood cell isolation on analysis of a population of spiked tumor cell-line cells and intrinsically present epithelial cells in the peripheral blood of breast and lung cancer patients and the sensitivity of their detection. Sucrose density separation did not enrich epithelial cells, and even depleted them, leading to a gross underestimation of their numbers (3/13 positive, between 2.9 and 50 cells/mL) in comparison to red blood cell lysis (13/13 positive, between 77,200 and 800 cells/mL). Short-term storage of whole blood samples for up to 7 days had little influence on the number of epithelial cells recovered. The effectiveness of magnetic bead enrichment was dependent on the number of relevant cells and the volume used for enrichment. Red blood cell lysis and fluorochrome-labeled antibody staining in a no-wash procedure with subsequent laser scanning cytometry allowed the detection of circulating epithelial cells in 92% of breast and lung cancer patients. Two examples of how this method can be applied for the longitudinal analysis in individual patients are shown, with an increase in numbers preceding relapse and a decrease paralleling tumor reduction. The proposed simple and easy method allows close monitoring, which may help in real-time analysis of the response of solid tumors, especially their systemic component, to therapy and hopefully will contribute to more individually tailored therapy.

Nanotech approaches to drug delivery and imaging

Nanotechnology, a multidisciplinary scientific undertaking, involves creation and utilization of materials, devices or systems on the nanometer scale. The field of nanotechnology is currently undergoing explosive development on many fronts. The technology is expected to create innovations and play a critical role in various biomedical applications, not only in drug delivery, but also in molecular imaging, biomarkers and biosensors. Target-specific drug therapy and methods for early diagnosis of pathologies are the priority research areas where nanotechnology would play a vital role. This review considers different nanotechnology-based drug delivery and imaging approaches, and their economic impact on pharmaceutical and biomedical industries.