Previously, we demonstrated that A549, a human lung cancer cell line, could be adapted to the free radical nitric oxide (NO●). NO● is known to be over expressed in human tumors. The original cell line, A549 (parent), and the newly adapted A549-HNO (which has a more aggressive phenotype) serve as a useful model system to study the biology of NO●. To see if tumor cells can similarly be adapted to any free radical with the same outcome, herein we successfully adapted A549 cells to high levels of hydrogen peroxide (HHP). A549-HHP, the resulting cell line, was more resistant and grew better then the parent cell line, and showed the following characteristics: (1) resistance to hydrogen peroxide, (2) resistance to NO●, (3) growth with and without hydrogen peroxide, and (4) resistance to doxorubicin. Gene chip analysis was used to determine the global gene expression changes between A549-parent and A549-HHP and revealed significant changes in the expression of over 1,700 genes. This gene profile was markedly different from that obtained from the A549-HNO cell line. The mitochondrial DNA content of the A549-HHP line determined by quantitative PCR favored a change for a more anaerobic metabolic profile. Our findings suggest that any free radical can induce resistance to other free radicals; this is especially important given that radiation therapy and many chemotherapeutic agents exert their effect via free radicals. Utilizing this model system to better understand the role of free radicals in tumor biology will help to develop new therapeutic approaches to treat lung cancer.

During the late 19th century, a number of dye types were used in early microscopic investigations of simple plant and tissue materials (Cook 1997). These included (1) hematoxylin and eosin (H&E) used separately, (2) picric acid and carmine used concurrently, and, finally, (3) the combination of H&E (Cook 1997;Gill 2010). The H&E staining method evolved rapidly into a traditional staining standard used for morphological study within histology and cytology settings throughout the world (Cook 1997;Shi et al. 2011;Gill 2010). This standard staining technique is well known within the histopathology and cytopathology communities. The hematoxylin stains nuclei, nucleic acids, and other cellular components (such as keratohyalin granules) blue in color, while eosin normally stains both extracellular and cytoplasmic proteins red. As such, H&E is particularly useful in identifying morphological changes valuable in the diagnosis of cancer and other disease states. There are many H&E protocols available, with selection of the most appropriate being subject to the needs and setting of the investigation (Sullivan-Brown et al. 2011 AbstractElectrocautery and directed energy devices (DEDs)