
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Human Cancer Biology |
Authors' Affiliations: Departments of 1 Gynecologic Oncology and 2 Cancer Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas; 3 College of Medicine; 4 Department of Psychology, University of Iowa, Iowa City, Iowa; and 5 Division of Hematology-Oncology, Department of Medicine, University of California, Los Angeles, Los Angeles, California
Requests for reprints: Anil K. Sood, Department of Gynecologic Oncology, The University of Texas M.D. Anderson Cancer Center, Unit 1362, P.O. Box 301439, Houston, TX 77230-1439. Phone: 713-745-5266; Fax: 713-792-7586; E-mail: asood{at}mdanderson.org.
| Abstract |
|---|
|
|
|---|
Experimental Design: The ovarian cancer cells EG, SKOV3, and 222 were exposed to increasing levels of either norepinephrine, epinephrine, or cortisol, and the in vitro invasive potential was determined using the membrane invasion culture system. Additionally, the effects of these stress hormones on matrix metalloproteinase-2 (MMP-2) and MMP-9 were determined by ELISA. The effects of the ß-adrenergic agonist isoproterenol on in vivo tumor growth were determined using nude mice.
Results: Stress levels of norepinephrine increased the in vitro invasiveness of ovarian cancer cells by 89% to 198%. Epinephrine also induced significant increases in invasion in all three cell lines ranging from 64% to 76%. Cortisol did not significantly affect invasiveness of the EG and 222 cell lines but increased invasion in the SKOV3 cell line (P = 0.01). We have previously shown that ovarian cancer cells express ß-adrenergic receptors. The ß-adrenergic antagonist propanolol (1 µmol/L) completely blocked the norepinephrine-induced increase in invasiveness. Norepinephrine also increased tumor cell expression of MMP-2 (P = 0.02 for both SKOV3 and EG cells) and MMP-9 (P = 0.01 and 0.04, respectively), and pharmacologic blockade of MMPs abrogated the effects of norepinephrine on tumor cell invasive potential. Isoproterenol treatment resulted in a significant increase in tumor volume and infiltration in the SKOV3ip1 in vivo model, which was blocked by propranolol.
Conclusions: These findings provide direct experimental evidence that stress hormones can enhance the invasive potential of ovarian cancer cells. These effects are most likely mediated by stimulation of MMPs.
Immune system cells express receptors for glucocorticoids from the hypothalamic-pituitary-adrenal axis and catecholamines from the sympathetic nervous system. These signals alter several aspects of immune cell function, including cellular activation, cytokine production, and cell trafficking (4, 12). However, the direct effects of stress hormones (from the sympathetic nervous system and hypothalamic-pituitary-adrenal axis) on cancer cells have not been well characterized. We recently examined ovarian carcinoma cells to assess the expression of receptors for stress hormones and the functional consequences of their ligation (13). Those studies found significant effects of catecholamines on production of proangiogenic cytokines, which are mediated by ß-adrenergic activation of the cyclic AMP/protein kinase A signaling pathway (13). The catecholamines epinephrine and norepinephrine are components of the sympathetic response that are manufactured by nerves of the sympathetic nervous system and the adrenal medulla. Both norepinephrine and epinephrine are elevated in individuals with acute or chronic stress (14, 15) and all major catecholamine neurotransmitters are present in the ovary (16, 17). Among them, norepinephrine is the most abundant and plays functionally relevant roles in ovarian steroidogenesis and follicular development (1821). Catecholamine concentrations are substantially higher in the ovarian tissue than in circulating plasma (22). We have previously shown that norepinephrine and the ß-adrenergic agonist isoproterenol can enhance the production of a proangiogenic cytokine, vascular endothelial growth factor, by ovarian cancer cells (13). These effects were mediated by ß-adrenergic receptors and were completely blocked by ß-adrenergic antagonist propranolol. Increased production of proangiogenic factors suggests that catecholamines could potentially facilitate tumor metastasis in vivo. However, metastasis is a complex process involving several sequential, interrelated steps, each of which can be rate limiting. To produce clinically relevant lesions, metastatic cells must complete all the steps of the process (23). Invasion is a key step in the pathogenesis of metastasis (24, 25) but little is known about how catecholamines might affect the invasive potential of tumor cells. Indirect evidence suggests that catecholamines could potentially enhance invasive capacity because norepinephrine has been shown to affect tumor cell motility in vitro (2628) and circulating catecholamines have been associated in vivo with tissue expression of matrix metalloproteinases (MMP) that facilitate invasion (29, 30). Those data provide circumstantial evidence suggesting that catecholamines could potentially affect the cellular and molecular processes involved in tumor cell invasion but no studies have directly evaluated this hypothesis by examining invasive function (i.e., capacity of tumor cells to penetrate extracellular matrix; ref. 31).
In this study, we examined the effects of catecholamines and cortisol on the invasive potential of ovarian carcinoma cells and their production of key MMP proteins involved in tumor cell penetration of extracellular matrix. Results show that ß-adrenergic signaling significantly up-regulates the invasive capacity of three different ovarian cancer cell lines via ß-adrenergic regulation of MMP proteins.
| Materials and Methods |
|---|
|
|
|---|
Invasion assay. The membrane invasion culture system chamber was used to measure the in vitro invasiveness of all cell lines used in this study (25, 31, 33). Briefly, a polycarbonate membrane with 10 µmol/L pores (Osmonics, Livermore, CA) was uniformly coated with a defined basement membrane matrix consisting of human laminin/type IV collagen/gelatin and used as the intervening barrier to invasion. The defined matrix was prepared (stored at 4°C) in a 10 mL stock solution as follows: laminin (50 µg/mL), 1 mL + type IV collagen (50 µg/mL), 0.2 mL + gelatin (2 mg/mL), and 4 mL + 4.8 mL PBS. Using a disposable pipette, 1 mL of the matrix solution was dispensed across a long side of the membrane. An 8 mm glass rod was used to spread the matrix across the membrane and allowed to dry for 30 minutes. The matrix-coated filter was placed coated side up on the lower plate followed by carefully attaching the upper plate. Both upper and lower wells of the chamber were filled with serum-free RPMI containing 1x MITO+ (Collaborative Biomedical, Bedford, MA). Single-cell tumor suspensions were seeded into the upper wells at a concentration of 1 x 105 cells per well. Following a 24-hour incubation in a humidified incubator at 37°C with 5% CO2, cells that had invaded through the basement membrane were collected through the side port by replacing the medium in the lower chamber with 2 mmol/L EDTA/PBS (pH 7.4) for 20 minutes at 37°C. The cells recovered from the bottom of the filter were then loaded onto a dot blot manifold containing 3 µm pore polycarbonate filters, fixed, stained, and counted by light microscopy (25, 31). Invasiveness was calculated as the percentage of cells that had successfully invaded through the matrix-coated membrane to the lower wells relative to the total number of cells seeded into the upper wells. The invasion assays were done in triplicate and repeated once.
Determination of MMP concentration. Serum-free conditioned medium from cultures of ovarian cancer cells was collected at 3, 6, 12, and 24 hours following exposure to catecholamines or cortisol. The supernatants were microfuged to remove debris and then stored at 80°C. The samples were thawed only once for determining the MMP concentration. An identical number of cells were plated without the three-dimensional matrix for comparison. The protein concentration of total MMP-2 (pro-MMP-2 and active MMP-2) and total MMP-9 (92 kDa pro-MMP2 and 82 kDa active forms) were determined using Quantikine immunoassays (R&D Systems, Minneapolis, MN) as per the protocol of the manufacturer. The concentrations of active MMP-2 and MMP-9 were determined using the Biotrak Activity Assay System (Amersham Biosciences, Piscataway, NJ) as per the protocol of the manufacturer. The MMP experiments were done in triplicate and were repeated once.
MMP inhibition. Inhibition of the MMPs was accomplished using a chemically modified tetracycline (CMT-3; CollaGenex Pharmaceuticals, Newton, PA). CMT-3 retains broad-spectrum inhibitory activity against MMPs but does not possess antimicrobial properties (34, 35). CMT-3 (5 µg/mL) was added to the different wells of the chamber postseeding (34).
In vivo tumor model. Female nude mice were purchased from the National Cancer Institute-Frederick Cancer Research Facility (Frederick, MD). The mice were housed and maintained under specific pathogen-free conditions in facilities approved by the American Association for Accreditation of Laboratory Animal Care in accordance with current regulations and standards of the U.S. Department of Agriculture, DHHS, and the NIH. The mice were used according to institutional guidelines when they were 8 to 12 weeks of age. The tumor cells (SKOV3ip1) were harvested from subconfluent cultures by a brief exposure to 0.25% trypsin and 0.02% EDTA. Trypsinization was stopped with medium containing 10% fetal bovine serum. The cells were then washed once in serum-free medium and resuspended in HBSS (serum free). Only single-cell suspensions with >95% viability, as determined by trypan blue exclusion, were used for the injections. To produce tumors, 1 x 106 SKOV3ip1 cells (0.1 mL) were injected s.c. into the right flank of the nude mice. A total of five mice per group were used. Starting 24 hours after tumor cell injection, mice were treated with daily i.p. injections of PBS, isoproterenol (10 mg/kg), or isoproterenol (10 mg/kg) in combination with propranolol (2 mg/kg) for 7 days. All treatments were administered in a total volume of 200 µL. Eight days after tumor cell injection, mice were euthanized by cervical dislocation. Tumors were measured in two dimensions, dissected, and fixed in formalin. Tumor volume was calculated as (length / 2) x (width2). Tumor samples were analyzed using H&E staining. Representative images were taken from each tumor using a light microscope at x40 and x100 magnification.
Statistical analysis. The
2 test was used to determine differences between cell counts using SPSS (SPSS, Inc., Chicago, IL). Hormone-mediated changes in MMP concentrations over time were analyzed using a dose x time ANOVA with both factors treated as repeated measures. Differences in tumor volume were determined using Student's t test. P < 0.05 was considered statistically significant.
| Results |
|---|
|
|
|---|
3-fold enhancement in the frequency of penetrating cells at 10 µmol/L norepinephrine (P < 0.001; Fig. 1A). Similar effects were observed for the other cell lines studied, with norepinephrine producing peak increases in invasive capacity ranging from 2-fold in 222 cells (P = 0.02) to 2.8-fold in SKOV3 cells (P = 0.004; Fig. 1A). The catecholamine epinephrine also enhanced ovarian cancer cell invasive potential, although its effects were less pronounced than those of norepinephrine (Fig. 1B). Epinephrine induced dose-dependent increases in invasive capacity for all three cell lines with a 1.6-fold maximum increase in SKOV3 cells (P = 0.004), 1.8-fold in EG cells (P = 0.01), and 1.7-fold in the 222 cells (P = 0.04; Fig. 1B).
|
We have previously shown that the ovarian cancer cells used in this study express both ß1 and ß2 adrenergic receptors (13). To determine whether those receptors mediate catecholamine effects on invasive potential, we treated ovarian cancer cells with the broad ß-blocker propranolol immediately following their introduction into the membrane invasion culture system chamber and introduced catecholamines 30 minutes later. Propranolol (1 µmol/L) completely blocked norepinephrine-mediated increases in invasion (Fig. 2), but propranolol alone had no effect on invasive capacity (data not shown).
|
|
|
|
|
|
| Discussion |
|---|
|
|
|---|
The effects observed here take place at physiologically relevant concentrations of catecholamines. Basal circulating levels of norepinephrine range between 10 pmol/L and 1 nmol/L, with stress increasing these levels to 100 nmol/L (46). Circulating epinephrine levels range from 1 to 10 pmol/L, and increase up to 10 nmol/L under stress (46). Stress can also increase tissue catecholamine levels in the ovary via increased sympathetic activity, which has been shown to trigger precystic follicles (4750). However, in addition to the sympathetic innervation, the primate ovary contains the endogenous enzymatic machinery necessary for catecholamine biosynthesis (51). As a result, ovarian tissue levels of catecholamines can substantially exceed those in plasma (22). Therefore, the in vitro doses of catecholamines used in our experiments cover the spectrum of stress and nonstress levels that the tumor cells would be exposed to in vivo and are consistent with doses that promote biological effects in other in vitro studies (46, 5257). Thus, the present data suggest that catecholamine effects on ovarian cancer invasive potential occur at physiologically relevant levels of those hormones.
The ability to invade extracellular matrices plays an important role in metastasis and in development of blood flow to tumors. The process of tumor cell penetration of the host basement membrane consists of attachment, matrix dissolution, motility, and penetration (58). MMPs play a key role in these dynamics by degrading components of the extracellular matrix, such as collagen, laminins, fibronectins, elastins, and the protein core of proteoglycans (39, 40). Given their destructive potential, MMPs are normally expressed only when and where they are needed to support physiologic processes, such as embryonic development, wound healing, and placental development (59, 60). Aberrant expression of MMPs contributes to several pathologic conditions, including tumor cell invasion and metastasis. MMPs associated with ovarian carcinomas include MMP-2 and MMP-9 (32, 4145). MMP-2 is the primary gelatinolytic MMP secreted by ovarian cancer cells (32, 43) and MMP-9 contributes to the angiogenic switch that occurs during carcinogenesis (61, 62). Recently, Huang et al. (63) have shown that host-derived MMP-9 expression plays a critical role in angiogenesis and progressive growth of human ovarian tumors in mice. We have previously shown the critical role of specific MMPs in the in vitro matrix remodeling by ovarian cancer cells (31, 32). The present data show that physiologic stress hormones can significantly enhance the expression and activity of these key MMPs by ovarian cancer cells.
These data provide the first indication that MMPs might play a role in stress hormonemediated changes in ovarian cancer cell function. Previous studies have linked hormone dynamics to MMP production by other cell types. Yang et al. (29) examined the effects of stress on MMP levels using a blister chamber wound model on UV-Bexposed human forearm skin. In their study, plasma norepinephrine levels were correlated with high MMP-2 protein levels in damaged dermal tissue. Recent studies in mice also suggest that psychological stress can elevate MMP activity. Wu et al. stressed mice by social isolation and found increased expression of mRNA for MMP-2, MMP-9, matrix-type MMP-1, and urokinase-type plasminogen activator in colon tumors and liver tissues in stressed versus control mice (30). The present study shows similar effects in the context of ovarian cancer and it extends those findings to show the functional significance of increased MMP expression in facilitating tumor cell invasion of basement membrane-like structures. It is possible that other factors may also be involved in stress hormonestimulated invasion and will be examined in ongoing work in our laboratory.
In summary, our results show that stress hormones can directly increase the invasive potential of ovarian cancer cells via ß-adrenergic up-regulation of MMP-2 and MMP-9. In conjunction with previous studies showing ß-adrenergic regulation of other molecular processes involved in the metastatic cascade (26, 64), these results suggest that physiologic catecholamine activity could represent a new target for adjunctive therapies that seek to block metastatic processes during and after primary therapy. Understanding the neuroendocrine influences on cancer growth and progression might allow development of strategies to delay or prevent malignant disease.
| Footnotes |
|---|
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received 8/ 3/05; revised 9/30/05; accepted 10/26/05.
| References |
|---|
|
|
|---|
-aminobutyric acid is an inhibitory regulator for the migration of SW 480 colon carcinoma cells. Cancer Res 2002;62:64679.
in enhancement of invasion and metastasis of colon 26-L5 carcinoma cells in mice by social isolation stress. Oncol Res 1999;11:4619.[Medline]
2-adrenergic receptors. Mol Pharmacol 1997;51:71120.
3ß1 integrin but not the
6ß4 integrin. J Biol Chem 2004;279:4488996.This article has been cited by other articles:
![]() |
G. N. Armaiz-Pena, L. S. Mangala, W. A. Spannuth, Y. G. Lin, N. B. Jennings, A. M. Nick, R. R. Langley, R. Schmandt, S. K. Lutgendorf, S. W. Cole, et al. Estrous Cycle Modulates Ovarian Carcinoma Growth Clin. Cancer Res., May 1, 2009; 15(9): 2971 - 2978. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. A. N. Al-Wadei, H. K. Plummer III, and H. M. Schuller Nicotine stimulates pancreatic cancer xenografts by systemic increase in stress neurotransmitters and suppression of the inhibitory neurotransmitter {gamma}-aminobutyric acid Carcinogenesis, March 1, 2009; 30(3): 506 - 511. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. K. Lutgendorf, D. M. Lamkin, N. B. Jennings, J. M.G. Arevalo, F. Penedo, K. DeGeest, R. R. Langley, J. A. Lucci III, S. W. Cole, D. M. Lubaroff, et al. Biobehavioral Influences on Matrix Metalloproteinase Expression in Ovarian Carcinoma Clin. Cancer Res., November 1, 2008; 14(21): 6839 - 6846. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. M. Schuller, H. A.N. Al-Wadei, and M. Majidi Gamma-aminobutyric acid, a potential tumor suppressor for small airway-derived lung adenocarcinoma Carcinogenesis, October 1, 2008; 29(10): 1979 - 1985. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Sayed, S. Rane, J. Lypowy, M. He, I.-Y. Chen, H. Vashistha, L. Yan, A. Malhotra, D. Vatner, and M. Abdellatif MicroRNA-21 Targets Sprouty2 and Promotes Cellular Outgrowths Mol. Biol. Cell, August 1, 2008; 19(8): 3272 - 3282. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Benish, I. Bartal, Y. Goldfarb, B. Levi, R. Avraham, A. Raz, and S. Ben-Eliyahu Perioperative Use of {beta}-blockers and COX-2 Inhibitors May Improve Immune Competence and Reduce the Risk of Tumor Metastasis Ann. Surg. Oncol., July 1, 2008; 15(7): 2042 - 2052. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. D Conzen Environmental Stress and the Neuroendocrine Response: Is There a Cancer Connection? Am. Assoc. Cancer Res. Educ. Book, April 12, 2008; 2008(1): 255 - 262. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. M. Merritt, Y. G. Lin, W. A. Spannuth, M. S. Fletcher, A. A. Kamat, L. Y. Han, C. N. Landen, N. Jennings, K. De Geest, R. R. Langley, et al. Effect of Interleukin-8 Gene Silencing With Liposome-Encapsulated Small Interfering RNA on Ovarian Cancer Cell Growth J Natl Cancer Inst, March 5, 2008; 100(5): 359 - 372. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. N. Landen Jr, M. J. Birrer, and A. K. Sood Early Events in the Pathogenesis of Epithelial Ovarian Cancer J. Clin. Oncol., February 20, 2008; 26(6): 995 - 1005. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. N. Landen Jr., Y. G. Lin, G. N. Armaiz Pena, P. D. Das, J. M. Arevalo, A. A. Kamat, L. Y. Han, N. B. Jennings, W. A. Spannuth, P. H. Thaker, et al. Neuroendocrine Modulation of Signal Transducer and Activator of Transcription-3 in Ovarian Cancer Cancer Res., November 1, 2007; 67(21): 10389 - 10396. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. S. R. Sastry, Y. Karpova, S. Prokopovich, A. J. Smith, B. Essau, A. Gersappe, J. P. Carson, M. J. Weber, T. C. Register, Y. Q. Chen, et al. Epinephrine Protects Cancer Cells from Apoptosis via Activation of cAMP-dependent Protein Kinase and BAD Phosphorylation J. Biol. Chem., May 11, 2007; 282(19): 14094 - 14100. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. V. Yang, A. K. Sood, M. Chen, Y. Li, T. D. Eubank, C. B. Marsh, S. Jewell, N. A. Flavahan, C. Morrison, P.-E. Yeh, et al. Norepinephrine Up-regulates the Expression of Vascular Endothelial Growth Factor, Matrix Metalloproteinase (MMP)-2, and MMP-9 in Nasopharyngeal Carcinoma Tumor Cells Cancer Res., November 1, 2006; 66(21): 10357 - 10364. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |