PURPOSE: Lung cancer is the leading cause of cancer deaths world wide, and adenocarcinoma is the most common cell type. Majority of patients with lung cancer present at advanced stage of disease with only 14% amenable to surgery for cure. Thus treatment is palliative, and for patients with malignant effusions due to pleural metastasis, pleurodesis with talc is one method to prevent recurrence. Although talc is widely used in clinical practice and is the preferred pleurodesis agent, exact mechanisms for its observed efficacy as well as whether it causes apoptosis of the cancer cells, have not been studied.
METHODS: Fine talc particles measuring 2μm were prepared using density gradient separation, and were confirmed against silicone beads of the same size as reference under high power inverted microscope. Talc was applied in the form of suspension at increasing concentrations of 25, 50 and 75 μg/ml to commercially procured lung adenocarcinoma cell line A549. For controls, silicone beads of similar size and at equivalent concentrations were used. Cell cultures were set up in 6-well plates with 105 cells/well using RPMI and 10% fetal calf serum. Apoptosis of lung cancer cells was measured using propidium iodide staining and flow cytometric analysis method at 24, 48, 72 and 96 hours. Normal mesothelial cells isolated through centrifugation of pleural fluid from patients with transudative pleural effusions were also subjected to talc and silicone beads at the same concentrations, and apoptosis measured.
RESULTS: Dose- and time-dependent apoptosis of A549 cells was observed with talc but not with silicone beads. No apoptosis of mesothelial cells was documented.
CONCLUSION: Our preliminary results demonstrate that fine particle talc causes apoptosis of lung adenocarcinoma cells in a dose and time dependent fashion.
CLINICAL IMPLICATIONS: Apoptosis of cancer cells observed with talc and not on normal mesothelial cells further supports its use for malignant effusion.
DISCLOSURE: Pyng Lee, None.