
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Molecular Oncology, Markers, Clinical Correlates |
Department of Urology, Dokkyo University School of Medicine, Tochigi 321-0293 [T. K., T. T., K. A.]; Departments of Urology [T. K., K. T.] and Pathology [H. A., Y. I.], Tokyo Metropolitan Tama Geriatric Hospital, Tokyo; and Department of Urology, Tokyo Medical and Dental University School of Medicine, Tokyo [H. O.], Japan
| ABSTRACT |
|---|
|
|
|---|
Experimental Design: Using Western blotting, we quantitated Rho and ROCK protein expression in paired tumor and nontumor surgical samples from 107 consecutive Japanese patients with bladder cancer.
Results: RhoA, RhoC, and ROCK were more abundant in tumors and metastatic lymph nodes than in nontumor bladder and uninvolved lymph nodes (P < 0.0001). Amounts of RhoA and RhoC protein, and ROCK protein expression correlated positively with one another (P < 0.0001). High RhoA, RhoC, and ROCK expression were related to poor tumor differentiation (P < 0.05, P < 0.01, and P < 0.01, respectively), muscle invasion (P < 0.001), and lymph node metastasis (P < 0.05). Kaplan-Meier plots linked high RhoA, RhoC, and ROCK protein expression to shortened disease-free and overall survival (P < 0.0001). By univariate analysis, high RhoA, RhoC, and ROCK protein expression predicted shortened disease-free and overall survival (P < 0.0001). By multivariate analysis, only RhoC was independently influenced in disease-free survival (P < 0.05), and RhoA and RhoC in overall survival (P < 0.001). In contrast, RhoB expression was inversely related to the grade and stage (P < 0.05), and its higher expression is associated with better overall survival (P < 0.05). In superficial tumors (Ta or T1; 63 patients), RhoA, RhoC, and ROCK were unrelated with recurrence-free survival. Overall survival in tumors invading muscle (T2 to T4; 44 patients) was significantly influenced by RhoA, RhoC, and ROCK in a Kaplan-Meier analysis (P < 0.0001, P < 0.0001, and P < 0.01, respectively). Whereas RhoA, RhoC, and ROCK independently predicted shortened overall survival in patients with invasive tumor by univariate analysis (P < 0.0001, P < 0.0001, and P < 0.01, respectively), only RhoC did so by multivariate analysis (P < 0.05).
Conclusion: Rho/ROCK pathway apparently involved in occurrence and progression of bladder cancer may be valuable prognostic markers.
| INTRODUCTION |
|---|
|
|
|---|
Cancer cell migration is central to the process of metastasis. Here too, rearrangements of the actin cytoskeleton are involved. Rearranging the actin cytoskeletal proteins in response to Rho is important for the ability of tumor cells to metastasize (7) . Overexpression of Rho has been linked to progression of human cancers (8, 9, 10) . Thus, action of the Rho/ROCK pathway takes part in cancer progression by regulating actin cytoskeleton reorganization; indeed, a specific ROCK inhibitor was found to suppress the tumor growth and metastasis (11 , 12) . These observations suggest that the Rho/ROCK pathway may be a molecular target for prevention of cancer invasion and metastasis. As no data have been reported concerning the Rho/ROCK pathway in progression of bladder cancer, we used Western blotting to quantify protein expression for Rho and ROCK in bladder cancer tissue and non-neoplastic portions of the same resected specimen. Relationships between Rho and ROCK expression, and pathologic features of the tumors were examined, as were influences of Rho and ROCK expression on patient survival. Such information might lead to improved protocols and case selection for adjuvant therapies.
| MATERIALS AND METHODS |
|---|
|
|
|---|
Western Blotting.
We dissected tumors and epitheliums by omitting stromal tissue. Western blotting was carried out as described previously (8)
. Briefly, 50 µg of cytosolic proteins were separated by SDS-PAGE (12.5% gel) for immunological detection of proteins. After transfer blotting from the gel to a nitrocellulose membrane, bound proteins were stained by Ponceau S to confirm that identical amounts of protein had been transferred. Rho and ROCK protein expression each was analyzed using specific antibodies (each diluted 1:2000; Santa Cruz Biotechnology, Santa Cruz, CA). After incubation with peroxidase-conjugated antirabbit IgG, these proteins were visualized by chemiluminescence. The blotted membrane was scanned densitometrically with a PDI imaging scanner (Agfa Japan, Tokyo, Japan) and analyzed with NIH Image software. For quantitation of proteins, relative amounts of Rho and ROCK in tumors were expressed as a ratio of absorbance of bands from the tumor specimen to those from the corresponding normal tissue, which was set to 1.0, by densitometrical analysis as described previously (8)
. Mean values from three experiments were obtained for tumor, nontumor, and lymph node tissues, respectively (9)
.
Immunohistochemistry.
Immunohistochemistry, using the same specific antibodies as antibodies for Western blotting, was performed to support the data obtained by Western blotting as described previously (8)
.
Statistical Analysis.
Results of Western blotting were analyzed statistically using the Mann-Whitney U test as described previously (9
, 10)
. The Spearman rank correlation coefficient was used to determine the relationship between protein expression for Rho and ROCK (14)
. Expression of Rho and ROCK protein, as well as tumor grade and stage of disease, were assessed in terms of survival by the Cox proportional hazards model using univariate and multivariate analysis. The Kaplan-Meier method was used to estimate survival as a function of time, and survival differences were assessed by the log-rank test. Ps < 0.05 were considered significant. Data were analyzed using commercially available software.
| RESULTS |
|---|
|
|
|---|
|
|
|
RhoA, RhoC, ROCK-I, and ROCK-II protein were more abundant in primary tumors that invaded bladder muscle and involved lymph nodes (4.15 ± 1.12, 4.93 ± 1.32, 2.41 ± 0.35, and 5.82 ± 0.91, respectively) than in those that did not (3.42 ± 0.93, P = 0.0251; 3.71 ± 0.94, P = 0.001; 2.01 ± 0.36, P = 0.0008; and 5.05 ± 1.02, P = 0.013, respectively; Fig. 4
). RhoB expression did not show a statistical difference between them (data not shown). Only RhoC protein level in tumors with muscle invasion and lymph node involvement (4.93 ± 1.32) were greater than in involved lymph nodes (4.08 ± 0.97; P = 0.029; Fig. 4
).
|
|
|
Univariate disease-free survival according to the Cox proportional hazards model was influenced significantly by RhoA, RhoC, ROCK-I, ROCK-II, stage, and grade (Table 1)
. By multivariate analysis, RhoC was an independent prognostic factor for disease-free survival. With regard to overall survival, whereas all of the factors analyzed were statistically significant by univariate analysis, only RhoC, RhoA, stage, and grade were significant by multivariate analysis (Table 1)
.
|
|
Cases of superficial disease (Ta and T1; 63 patients) were divided into those with RhoA expression above (27 patients) or below (36 patients) based on a mean of 2.61 (±0.41). In these superficial cases, a mean of RhoC was 2.53 (±0.38) with high expression in 27 patients and low expression in 36 patients. ROCK-I showed a mean of 1.48 (±0.29) with high expression in 35 patients and low expression in 28 patients, whereas for ROCK-II the mean was 3.20 (±0.49) with high expression in 29 patients and low expression in 34 patients. Expression of these proteins failed to affect recurrence-free survival in superficial tumors according to Cox and Kaplan-Meier analyses (data not shown).
RhoB, with a mean 0.85 (±0.16), low expression in 28 patients, and high expression in 35 patients, was not related to disease-free survival in superficial tumors (data not shown).
In tumor-invading muscle (T2 and higher; 44 patients), mean RhoA expression was 3.73 (±1.08), with high expression in 21 patients and low expression in 23 patients. For RhoC, the invasive cases showed a mean of 4.20 (±1.33), with high expression in 24 patients and low expression in 20 patients; for ROCK-I, the mean was 2.22 (±0.39), with high expression in 26 patients and low expression in 18 patients; for ROCK-II, the mean was 5.45 (±1.29), with high expression in 30 patients and low expression in 14 patients. Kaplan-Meier plots showed that high expression of RhoA, RhoC, ROCK-I, or ROCK-II protein each had a significant influence on disease-free survival in the invasive tumor group (P = 0.0112, P = 0.0109, P = 0.0129, and P = 0.0295, respectively; Fig. 8, AD
), as well as on overall survival (P < 0.0001, P < 0.0001, P = 0.0002, and P = 0.002, respectively; Fig. 8, EH
). Although all four of the proteins predicted disease-free and overall survival of invasive cases in univariate analyses, only RhoC remained significant for overall survival in a multivariate analyses (Table 2)
.
|
|
| DISCUSSION |
|---|
|
|
|---|
Overexpression of Rho has been reported in a number of human cancers (8, 9, 10 , 15) . Furthermore, several lines of evidence directly link Rho to acquisition of a migratory, invasive, and metastatic phenotype (16) . Rho is important for the ability of tumor cells to metastasize (7) . We showed that RhoA, RhoC, and ROCK, but not RhoB protein expressions were greater in bladder tumors than in parts of the same bladder resection specimen containing no tumor.
RhoA, the prototype of Rho, and ROCK are best characterized in human cancers (11 , 12 , 14) . High expression of RhoA facilitates translocation of this protein from the cytosol to the cell membrane, where it becomes activated and promotes invasion (17) . Increased expression of Rho has been linked to higher stage in human cancers (8, 9, 10) . ROCK mediates responses in the pathway initiated by Rho, and regulates dynamic reorganization of cytoskeletal proteins such as in formation of stress fibers and focal adhesions (18) . Although at least two ROCK isoforms, ROCK-I and ROCK-II, may be expressed in the same species (19) , differences in their roles in Rho-mediated signaling remain unclear. In the present study, a positive correlation was seen in tumor tissues between expression of RhoA and ROCK. Moreover, higher expressions of ROCK-I/ROCK-II, as well as RhoA in the primary lesion was associated not only with higher stages of disease, but also with poorer survival, in particular in tumors invading muscle. Whereas only weakly detectable in normal lymph nodes tissue, RhoA and ROCK were abundant in lymph node with metastasis. Furthermore, both were significantly more abundant in tumors invading muscle that showed lymph node involvement than in those without nodal involvement. Ability to enter either blood or lymphatic vasculature is necessary for tumor cells to metastasize to distant sites (20) . RhoA and ROCK reportedly are required in both endothelial and the migrating cells for them to cross the vascular endothelium (21 , 22) .
RhoC, high homology to RhoA, has been shown to be the most associated with metastasis of cancer cells among Rho subfamily using high-density DNA microassays (23) . Moreover, overexpression of RhoC has been associated with the progression of pancreatic ductal adenocarcinoma (10) and inflammatory breast cancer (24) . It has been reported that overexpression of RhoC leads to increased expression of angiogenic factors (25) , and that RhoC overexpression also promotes the ability of melanoma cells to exit the blood and colonize the lung (23) . Therefore, taken together, the RhoA and RhoC/ROCK pathway is likely to be involved in local invasion and lymph node metastasis of tumor cells. Expression of pathway components may be a useful prognostic marker in bladder cancer.
RhoB also regulates actin organization. It is required for signaling apoptosis in transformed cells that are exposed to farnesyltransferase inhibitors, DNA-damaging agents, or Taxol. Genetic analysis in mice indicates that RhoB is dispensable for normal cell physiology, but that it has a suppressor or negative modifier function in stress-associated process, including cancer (26) . As well as in bladder cancer shown in the present study, it has been reported that RhoB expression is readily detected in normal epithelium, carcinomas in situ, and well-differentiated tumors, but it becomes weak to undetectable as tumors become deeply invasive and poorly differentiated in human head and neck squamous cell carcinomas, and RhoA protein levels increase with tumor progression (27) . Furthermore, we showed here that higher expression of RhoB was associated with favorable prognosis in bladder cancer. A negative role in growth control and/or transformation would contrast with the positive effects of RhoA and RhoC in these processes (26) . These findings give additional support to the notion that RhoB may play a tumor-suppressive role in human cancers.
Although it is likely that RhoA, RhoB, and RhoC share common functions in regulating stress fiber formation (28) , these proteins differ in subcellular location (29) and regulation of expression (30 , 31) . Therefore, abnormal regulation of expression patterns between members of the Rho subfamily in neoplastic cells may be involved in carcinogenesis and cancer progression.
We did not analyze the effect of treatment modalities on outcome of patients in the current study. Despite reports that tumor burden can be reduced for superficial tumors by intravesical chemotherapy and Bacillus Calmette-Guerin immunotherapy or systemic combined methotrexate, vinblastine, Adriamycin, and cisplatin chemotherapy in the case of invasive tumors, these outcomes were poorer than expected (32 , 33) . In the present study, higher expression of RhoA, RhoC, and ROCK was associated with shorter survival in bladder cancer. New treatment modalities such as cell migration inhibitors may be important possibilities to consider.
A specific ROCK inhibitor, Y-27632 (34 , 35) , has been reported to block both Rho-mediated activation of actomyosin and invasive activity of cultured rat MM1 hepatoma cells (12) . Continuous treatment with this inhibitor reduced dissemination of MM1 cells implanted into the peritoneal cavity of syngeneic rats (11) . These reports suggested that ROCK inhibition may represent a way to prevent cancer invasion and metastasis by inhibiting cell migration and morphological alterations. We will need to study the effect of ROCK inhibitors on bladder cancer cells in vitro and in vivo. These results may suggest improved treatment strategies.
Mutations of Rho have not been identified in human tumors (10 , 36 , 37) . Although mutational change in Rho genes was not within the scope of the current study, this should be investigated in the future.
Many downstream effectors are likely to be involved in the Rho signaling pathway (4) . p140mDia, a mammalian homologue of the Drosophila diaphanous, controls actin polymerization (38) . ROCK and p140mDia act cooperatively in the stress fiber formation to mediate Rho effects (39) . Other possible downstream effectors and their roles need to be explored in bladder cancer. Rho family GTPases, including Rho, Rac, and Cdc42, have been shown to differentially and cooperatively contribute to triggering of invasive behavior in tumor cells (40) . More complete understanding of how Rho family GTPases mutually and specifically interact in bladder cancer may throw light on the therapeutic approaches.
| FOOTNOTES |
|---|
1 Supported in part by grants-in-aid for scientific research from the Ministry of Education, Culture, Sports, Science and Technology, Japan (to T. K.). ![]()
2 To whom requests for reprints should be addressed, at Department of Urology, Dokkyo University School of Medicine, 880 Kitakobayashi Mibu-machi, Tochigi 321-0293, Japan. Phone: 81-282-87-2162; Fax: 81-282-86-7533; E-mail: kamait{at}dokkyomed.ac.jp ![]()
Received 4/ 8/02; revised 12/20/02; accepted 1/ 7/03.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
J. Chen, E. Guerriero, K. Lathrop, and N. SundarRaj Rho/ROCK Signaling in Regulation of Corneal Epithelial Cell Cycle Progression Invest. Ophthalmol. Vis. Sci., January 1, 2008; 49(1): 175 - 183. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Faried, L. S. Faried, N. Usman, H. Kato, and H. Kuwano Clinical and Prognostic Significance of RhoA and RhoC Gene Expression in Esophageal Squamous Cell Carcinoma Ann. Surg. Oncol., December 1, 2007; 14(12): 3593 - 3601. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Lu, K. L. Knutson, E. Gad, and M. L. Disis The Tumor Antigen Repertoire Identified in Tumor-Bearing Neu Transgenic Mice Predicts Human Tumor Antigens Cancer Res., October 1, 2006; 66(19): 9754 - 9761. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. R. Croft and M. F. Olson The Rho GTPase Effector ROCK Regulates Cyclin A, Cyclin D1, and p27Kip1 Levels by Distinct Mechanisms Mol. Cell. Biol., June 15, 2006; 26(12): 4612 - 4627. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. H.-Y. Leung, Y.-P. Ching, J. W. P. Yam, C.-M. Wong, T.-O. Yau, D.-Y. Jin, and I. O.-L. Ng Deleted in liver cancer 2 (DLC2) suppresses cell transformation by means of inhibition of RhoA activity PNAS, October 18, 2005; 102(42): 15207 - 15212. [Abstract] [Full Text] [PDF] |
||||
![]() |
C.-M. Wong, J. W.-P. Yam, Y.-P. Ching, T.-O. Yau, T. H.-Y. Leung, D.-Y. Jin, and I. O.-L. Ng Rho GTPase-Activating Protein Deleted in Liver Cancer Suppresses Cell Proliferation and Invasion in Hepatocellular Carcinoma Cancer Res., October 1, 2005; 65(19): 8861 - 8868. [Abstract] [Full Text] [PDF] |
||||
![]() |
W-B Zhong, Y-C Liang, C-Y Wang, T-C Chang, and W-S Lee Lovastatin suppresses invasiveness of anaplastic thyroid cancer cells by inhibiting Rho geranylgeranylation and RhoA/ROCK signaling Endocr. Relat. Cancer, September 1, 2005; 12(3): 615 - 629. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Titus, H. F. Frierson Jr., M. Conaway, K. Ching, T. Guise, J. Chirgwin, G. Hampton, and D. Theodorescu Endothelin Axis Is a Target of the Lung Metastasis Suppressor Gene RhoGDI2 Cancer Res., August 15, 2005; 65(16): 7320 - 7327. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Ramirez de Molina, D. Gallego-Ortega, J. Sarmentero, M. Banez-Coronel, Y. Martin-Cantalejo, and J. C. Lacal Choline Kinase Is a Novel Oncogene that Potentiates RhoA-Induced Carcinogenesis Cancer Res., July 1, 2005; 65(13): 5647 - 5653. [Abstract] [Full Text] [PDF] |
||||
![]() |
J.-Y. Lang, H. Chen, J. Zhou, Y.-X. Zhang, X.-W. Zhang, M.-H. Li, L.-P. Lin, J.-S. Zhang, M. P. Waalkes, and J. Ding Antimetastatic Effect of Salvicine on Human Breast Cancer MDA-MB-435 Orthotopic Xenograft Is Closely Related to Rho-Dependent Pathway Clin. Cancer Res., May 1, 2005; 11(9): 3455 - 3464. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Zhou and R. H. Kramer Integrin Engagement Differentially Modulates Epithelial Cell Motility by RhoA/ROCK and PAK1 J. Biol. Chem., March 18, 2005; 280(11): 10624 - 10635. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. R. Croft, E. Sahai, G. Mavria, S. Li, J. Tsai, W. M. F. Lee, C. J. Marshall, and M. F. Olson Conditional ROCK Activation In vivo Induces Tumor Cell Dissemination and Angiogenesis Cancer Res., December 15, 2004; 64(24): 8994 - 9001. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. Wang, S. Goswami, K. Lapidus, A. L. Wells, J. B. Wyckoff, E. Sahai, R. H. Singer, J. E. Segall, and J. S. Condeelis Identification and Testing of a Gene Expression Signature of Invasive Carcinoma Cells within Primary Mammary Tumors Cancer Res., December 1, 2004; 64(23): 8585 - 8594. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. J. Simpson, A. S. Dugan, and A. M. Mercurio Functional Analysis of the Contribution of RhoA and RhoC GTPases to Invasive Breast Carcinoma Cancer Res., December 1, 2004; 64(23): 8694 - 8701. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Liu, F. Bi, Y. Pan, L. Sun, Y. Xue, Y. Shi, X. Yao, Y. Zheng, and D. Fan Reversal of the Malignant Phenotype of Gastric Cancer Cells by Inhibition of RhoA Expression and Activity Clin. Cancer Res., September 15, 2004; 10(18): 6239 - 6247. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. G. Strauss, A. Dimitrakopoulou-Strauss, D. Koczan, L. Bernd, U. Haberkorn, V. Ewerbeck, and H.-J. Thiesen 18F-FDG Kinetics and Gene Expression in Giant Cell Tumors J. Nucl. Med., September 1, 2004; 45(9): 1528 - 1535. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. M. Vasiliev, T. Omelchenko, I. M. Gelfand, H. H. Feder, and E. M. Bonder From the Cover: Rho overexpression leads to mitosis-associated detachment of cells from epithelial sheets: A link to the mechanism of cancer dissemination PNAS, August 24, 2004; 101(34): 12526 - 12530. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Kamai, T. Yamanishi, H. Shirataki, K. Takagi, H. Asami, Y. Ito, and K.-I. Yoshida Overexpression of RhoA, Rac1, and Cdc42 GTPases Is Associated with Progression in Testicular Cancer Clin. Cancer Res., July 15, 2004; 10(14): 4799 - 4805. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. M. McHardy, R. Sinotte, A. Troussard, C. Sheldon, J. Church, D. E. Williams, R. J. Andersen, S. Dedhar, M. Roberge, and C. D. Roskelley The Tumor Invasion Inhibitor Dihydromotuporamine C Activates RHO, Remodels Stress Fibers and Focal Adhesions, and Stimulates Sodium-Proton Exchange Cancer Res., February 15, 2004; 64(4): 1468 - 1474. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Ikoma, T. Takahashi, S. Nagano, Y.-M. Li, Y. Ohno, K. Ando, T. Fujiwara, H. Fujiwara, and K.-i. Kosai A Definitive Role of RhoC in Metastasis of Orthotopic Lung Cancer in Mice Clin. Cancer Res., February 1, 2004; 10(3): 1192 - 1200. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||