LUNX mRNA-positive cells at different time points predict prognosis in patients with surgically resected nonsmall cell lung cancer

LUNX is a lung-specific gene whose messenger ribonucleic acid (mRNA) expression is strictly limited to normal lung tissue and nonsmall cell lung cancer (NSCLC) tissue. The aim of this study was to investigate whether the detection of LUNX mRNA-positive circulating tumor cells (CTC)s in peripheral blood at different time points is useful for predicting disease recurrence, disease-free survival (DFS), and overall survival (OS) in NSCLC patients undergoing surgery. Serial blood samples from 68 patients with stage I-IIIA NSCLC were examined by real-time quantitative polymerase chain reaction assay targeting LUNX mRNA before (T0) and after surgery (T1) and after the completion of adjuvant chemotherapy (T2). Results showed that LUNX mRNA-positive CTCs were detected in 40 of 68 NSCLC patients (58.8%) before surgery; the detection rates of LUNX mRNA-positive CTCs at T1 and T2 time points were 32.4% (22/68) and 33.3% (20/60), respectively. The detection of LUNX mRNA-positive CTC at 3 time points was associated with lymph node status and pathologic stage. During the follow-up period, patients with LUXN mRNA-positive CTC at 3 time points had a higher relapse rate and a shorter DFS and OS than those without. Multivariate analysis revealed that presence of LUNX mRNA-positive CTC at T1 and T2 time points was an independent unfavorable factor for DFS and OS. In conclusion, detection of LUNX mRNA-positive CTC after surgery and the completion of adjuvant chemotherapy in patients with stage I-IIIA NSCLC are highly predictive for DFS and OS. This technique could aid in the prediction of prognosis and design of tailored treatment.

Separation of tumor cells with dielectrophoresis-based microfluidic chip

The present work demonstrates the use of a dielectrophoretic lab-on-a-chip device in effectively separating different cancer cells of epithelial origin for application in circulating tumor cell (CTC) identification. This study uses dielectrophoresis (DEP) to distinguish and separate MCF-7 human breast cancer cells from HCT-116 colorectal cancer cells. The DEP responses for each cell type were measured against AC electrical frequency changes in solutions of varying conductivities. Increasing the conductivity of the suspension directly correlated with an increasing frequency value for the first cross-over (no DEP force) point in the DEP spectra. Differences in the cross-over frequency for each cell type were leveraged to determine a frequency at which the two types of cell could be separated through DEP forces. Under a particular medium conductivity, different types of cells could have different DEP behaviors in a very narrow AC frequency band, demonstrating a high specificity of DEP. Using a microfluidic DEP sorter with optically transparent electrodes, MCF-7 and HCT-116 cells were successfully separated from each other under a 3.2 MHz frequency in a 0.1X PBS solution. Further experiments were conducted to characterize the separation efficiency (enrichment factor) by changing experimental parameters (AC frequency, voltage, and flow rate). This work has shown the high specificity of the described DEP cell sorter for distinguishing cells with similar characteristics for potential diagnostic applications through CTC enrichment.

DETECTION OF DISSEMINATED TUMOR CELLS IN PERIPHERAL BLOOD

Metastases are the major cause of cancer-related deaths in patients with solid epithelial malignancies, such as breast, colorectal and prostate carcinomas. Hematogenous spreading of tumor cells from a primary tumor can be considered as a crucial step in the metastasis cascade leading eventually to the formation of clinically manifest metastases. Consequently, as shown in recent studies, the detection of disseminated tumor cells in peripheral blood might be of clinical relevance with respect to individual patient prognosis and staging or monitoring of therapy. However, the rarity of disseminated tumor cells in peripheral blood renders the application of sensitive techniques mandatory for their detection. The emergence of highly sophisticated reverse transciptase-polymerase chain reaction (RT-PCR) assays, combining a preanalytical enrichment step with the assessment of multiple molecular tumor markers expressed in disseminated tumor cells, provides a powerful tool in detecting disseminated tumor cells with high sensitivity and specificity. This review will discuss currently used tumor markers as well as experimental means to enhance the sensitivity and specificity of RT-PCR assays to detect disseminated tumor cells in the peripheral blood of patients with breast, colorectal, and prostate cancers, and their clinical relevance assessed in recent studies.