M.W. Roomi, J. Monterrey, V. Ivanov, M. Rath and A. Niedzwiecki
Dr. Rath Research Institute, Oncology Division, Santa Clara, CA
The 99th Annual Meeting of the AACR, San Diego, California, April 12-16, 2008
Proceedings of the 99th Annual Meeting of the AACR, Abstract #1140, p 269
Lung cancer (LC), the most common cause of cancer death is associated mainly with tobacco smoking, as well as with radon and asbestos exposure. Malignant mesothelioma (MM) is a highly aggressive tumor caused by exposure to asbestos. Extracellular matrix metalloproteinases (MMPs), particularly MMP-2 (gelatinase A) and MMP-9 (gelatinase B), secreted by LC and MM play crucial roles in tumor invasion and metastasis. Gelatinases have been shown to be regulated by cytokines, mitogens and inhibitors. However their role in two related cancers, LC and MM has been barely unveiled.
This study examined the role of cytokines, mitogens and inhibitors in regulation of MMPs in LC and MM cell lines.
Human LC (A 549) and MM (MSTO-211H) cell lines (ATCC) were cultured in F12 K and RPMI media respectively, supplemented with 10% FBS and antibiotics in 24-well cultured plates. At near confluence, cells were washed with PBS and incubated in serum free medium at various doses with: PMA (10-200 ng/ml), TNF-alpha (0.1-25 ng/ml), Il-1 beta (0.1- 25 ng/ml), LPS (10-100 µg/ml, EGCG and doxycycline (10-100 µg/ml) without and with PMA, actinomycin-D, cyclohexamide, retinoic acid, and dexamethasone. In addition some cells were exposed to a nutrient mixture (NM), containing lysine, proline, ascorbic acid and green tea extract without and with PMA. After 24 hrs the medium was removed and analyzed for MMP-2 and MMP-9 by zymography and quantified by densitometry.
LC expressed only one band corresponding to MMP-2 whereas MM expressed two bands, a major band (MMP-2) and a faint band (MMP-9). PMA moderately stimulated MMP-2 secretion and profoundly stimulated MMP-9 in LC cells. In contrast PMA had a moderate suppressing effect on MMP-2 and a stimulatory dose dependent effect on MMP-9 in the MM cell line. TNF-alpha had a stimulatory effect on MMP-2 in LC and moderate inhibitory effect on MM cell lines. Il-1 had no effect on MMP-2 in LC cell line, but an inhibitory effect in MM cell line. TNF-alpha and Il-1 had no effect on MMP-9 secretion in both cancer cell lines. LPS up-regulated MMP-2 in a dose dependent fashion in LC whereas it had an opposite effect in MM. EGCG and doxycycline without and with PMA down regulated the expression of MMP-2 and MMP-9 in a dose dependent manner. In addition, actinomycin-D, cyclohexamide, retinoic acid and dexamethasone also had inhibitory effects on MMP-2 in both cancer cell lines. NM without and with PMA showed a dose dependent decrease in MMP-2 and MMP-9 secretion in both cell lines.
Our results showed that cytokines had variable regulatory effects on MMP secretion in LC and MM, while inhibitors suppressed MMP secretion in both cell lines. These results suggest use of these regulators as therapeutic strategies in the management of LC and MM.
Extracellular matrix metalloproteinases (MMPs), particularly MMP-2 (gelatinase A) and MMP-9 gelatinase B) play critical roles in tumor invasion and metastasis. It has been shown that cytokines, mitogens and inhibitors regulate gelatinases. However, their roles in two aggressive cancers, lung cancer (LC) and malignant mesothelioma (MM) have been barely investigated. We studied the effect of inducers such as PMA, TNF-alpha, IL-1 beta and LPS and inhibitors such as EGCG, doxycycline, actinomycin-D, cyclohexamide, retinoic acid and a nutrient mixture (NM) containing lysine, proline, ascorbic acid and green tea extract on MMP secretion in these two cell lines. Our results showed that cytokines ad variable regulatory effects on MMP secretion in LC and MM, while inhibitors suppressed MMP secretion in both cell lines. These results are significant as they indicate that these regulators have therapeutic potential in management of LC and MM.