[Targeted therapies and radiation therapy in non-small cell lung cancer]

Microfluidic Platform for Studying Chemotaxis of Adhesive Cells Revealed a Gradient-Dependent Migration and Acceleration of Cancer Stem Cells

Recent studies reveal that solid tumors consist of heterogeneous cells with distinct phenotypes and functions. However, it is unclear how different subtypes of cancer cells migrate under chemotaxis. Here, we developed a microfluidic device capable of generating multiple stable gradients, culturing cells on-chip, and monitoring single cell migratory behavior. The microfluidic platform was used to study gradient-induced chemotaxis of lung cancer stem cell (LCSC) and differentiated LCSC (dLCSC) in real time. Our results showed the dynamic and differential response of both LCSC and dLCSC to chemotaxis, which was regulated by the β-catenin dependent Wnt signaling pathway. The microfluidic analysis showed that LCSC and dLCSC from the same origin behaved differently in the same external stimuli, suggesting the importance of cancer cell heterogeneity. We also observed for the first time the acceleration of both LCSC and dLCSC during chemotaxis caused by increasing local concentration in different gradients, which could only be realized through the microfluidic approach. The capability to analyze single cell chemotaxis under spatially controlled conditions provides a novel analytical platform for the study of cellular microenvironments and cancer cell metastasis.

A phase II trial of erlotinib as maintenance treatment after concurrent chemoradiotherapy in stage III non-small-cell lung cancer (NSCLC): a Galician Lung Cancer Group (GGCP) study

PURPOSE

This single arm, phase II study aims to evaluate the role of epidermal growth factor receptor-tyrosine-kinase inhibitor erlotinib as maintenance therapy following concurrent chemoradiotherapy (cCRT) in unresectable locally advanced non-small-cell lung cancer (NSCLC).

METHODS

Patients with unresectable stage IIIA o dry IIIB NSCLC with no evidence of tumor progression after receiving a standard cCRT regimen with curative intent were included. Oral erlotinib 150 mg/day was administered within 4-6 weeks after the end of the cCRT for a maximum of 6 months if no disease progression or intolerable toxicity occurred. Primary end point was the progression-free rate (PFR) at 6 months. Secondary end points included time to progression (TTP) and overall survival (OS).

RESULTS

Sixty-six patients were enrolled and received maintenance treatment with erlotinib [average: 4.5 months (95 % CI 4.0-5.0)]. PFR at 6 months was 63.5 % (41/66). With a median follow-up of 22.7 months (95 % CI 13.5-37.1), the median TTP was 9.9 months (95 % CI 6.2-12.1), and the median OS was 24.0 months (95 % CI 17.3-48.6). Most common adverse events (AEs) related to erlotinib were rash (78.8 %; 16.7 % grade 3), diarrhea (28.8 %; 1.5 % grade 3), fatigue (15.2 %; 1.5 % grade 3), anorexia (7.6 %; 1.5 % grade 3) and vomiting (4.6 %; none grade 3). Five patients (7.6 %) were withdrawn due to AEs.

CONCLUSIONS

Erlotinib as maintenance therapy is an active treatment after cCRT in unselected patients with stage III NSCLC, reaching a 6-month PFR of 63.5 % and a median OS of 24 months. The safety profile of maintenance erlotinib was as expected and manageable.

Cell division cycle 25 homolog c effects on low-dose hyper-radiosensitivity and induced radioresistance at elevated dosage in A549 cells

The underlying mechanisms behind both low-dose hyper-radiosensitivity (HRS) and induced radioresistance (IRR), generally occurring at elevated radiation levels, remain unclear; however, elucidation of the relationship between cell cycle division 25 homolog c (Cdc25c) phosphatase and HRS/IRR may provide important insights into this process. Two cell lines with disparate HRS status, A549 and SiHa cells, were selected as cell models for comparison of dose-dependent Cdc25c phosphatase expression subsequent to low-dose irradiation. Knockdown of Cdc25c in A549 cells was mediated by transfection with a pGCsi-RAN-U6neo vector containing hairpin siRNA sequences. S216-phosphorylated Cdc25c protein [p-Cdc25c (Ser216)], cell survival and mitotic ratio were measured by western blot, colony-forming assay and histone H3 phosphorylation analysis. Variant p-Cdc25c (Ser216) expression was observed in the two cell lines after irradiation. The p-Cdc25c (Ser216) expression noted in SiHa cells after administration of 0-1 Gy radiation was similar to the radioresistance model; however, in A549 cells, the dose response for the phosphorylation of the Cdc25c Ser216 residue overlapped the level required to overcome the HRS response. Furthermore, Cdc25c repression prior to low-dose radiation induced more distinct HRS and prevented the development of IRR. The dose required to overcome the HRS response coincided with the effect of early G2-phase checkpoint arrest in A549 cells (approximately 0.3 Gy), and Cdc25c knockdown in A549 cells (approximately 0.5 Gy) corresponded to the phosphorylation of the Cdc25c Ser216 residue. Resultant data confirmed that dose-dependent Cdc25c phosphatase does effectively act as an early G2-phase checkpoint, thus indicating mechanistic importance in the HRS to IRR transition in A549 cells.