| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Experimental Therapeutics, Molecular Targets, and Chemical Biology |
1 Department of Radiation Oncology, Institutes of 2 Clinical Immunology, and 3 Pathology, University of Erlangen-Nuremberg, Erlangen, Germany
Requests for reprints: Franz Rödel, Department of Radiation Therapy, Universitätsstr. 27, 91054 Erlangen, Germany. Phone: 49-9131-853-3405; Fax: 49-9131-853-9335; E-mail: franz.roedel{at}strahlen.med.uni-erlangen.de.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
In general, adenocarcinomas including colorectal cancer tend to be less radioresponsive. Recent data from preoperative radiochemotherapy in rectal cancer, however, indicate a broad variety in tumor response. In our recently completed randomized trial comparing preoperative with standard postoperative radiochemotherapy in rectal cancer (CAO/ARO/AIO-94), a standardized histopathologic tumor regression grading was prospectively applied. Out of 385 patients, 10% revealed complete response, whereas 53%, 14%, 15%, and 8% of patients showed good, moderate, minimal, or no regression treatment response, respectively (2). Despite of uniform treatment protocol, the observed heterogeneity in treatment response is most probably caused by differences not only in tumor size and differentiation but also in the genetic profile of the individual lesions.
In the clinical setting, we and others have previously shown that a high level of pretreatment apoptosis emerged as a significant predictor of tumor regression after preoperative radiochemotherapy in rectal cancer (4–6). In vitro studies, using colorectal cancer cell lines with different intrinsic radiosensitivities further confirmed that spontaneous and radiation-induced apoptosis correlated closely with radiation response (7). Although it is clear from the literature that apoptosis propensity may be regulated by various factors, including p53 and the bcl-2 family, a prominent role of survivin, a structurally unique member of the inhibitor of apoptosis family (8–10), has recently been shown for colorectal cancer tumorigenesis and prognosis (11–16). In a panel of colorectal cell lines, we have previously shown an inverse relationship between levels of survivin expression, rates of spontaneous and radiation-induced apoptosis, and radiosensitivity as determined by the clonogenic assay (7).
In the present study, we sought to assess the effects of attenuation of survivin expression, accomplished through short interfering RNA (siRNA)–induced down-regulation of survivin mRNA and protein, on the response of colorectal cell lines with diverse intrinsic radiosensitivities and different levels of survivin expression (SW480, HCT-15), and to elucidate possible underlying mechanisms by which survivin may mediate radiation resistance. Furthermore, to confirm the observed preclinical data at the clinical level, we analyzed the impact of survivin expression, as determined in the pretreatment tumor material of 59 uniformly treated rectal cancer patients, on the efficacy of preoperative radiochemotherapy.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Transfection of short interfering RNA and irradiation. The sequence of the double-stranded siRNA (Eurogenetec, Searing, Belgium) used for attenuation of survivin expression corresponded to a 21 bp sequence kindly provided by Dr. Matthias Truss, Pediatric Clinic, University of Berlin (sense, 5'-CUG-GAC-AGA-GAA-AGA-GCC-ATT-3'; antisense, 5'-UGG-CUC-UUU-CUC-UGU-CCA-GTT-3'). Cells were treated in parallel with a green fluorescence protein (GFP)-siRNA (sense, 5'-GGU-GUG-CUG-UUU-GGA-GGU-CTT-3'; antisense, 5'-GAA-CUC-CAA-ACA-GCA-CAC-CTT-3') as a nonspecific control (MWG, Ebersberg, Germany). Cells (5 x 105) were seeded in 25 cm2 flasks 24 hours before transfection resulting in a confluence of the cell monolayer of 50% to 60%. Cells were then cultured in serum-free OptiMEM (Invitrogen, Karlsruhe, Germany) for 4 hours. Survivin-specific siRNA or GFP-siRNA (each 50 nmol) were mixed with OligofectAMINE plus (Invitrogen) and added to the cells. After 4 hours at 37°C, cells were cultivated in DMEM supplemented with 20% heat-inactivated FCS. Twenty-four hours after transfection, cells were irradiated at room temperature using X-ray orthovoltage-irradiation (Stabilipan, Siemens, München, Germany) at 250 kV/15 mA/40 cm focus-surface distance at a dose rate of 1.15 Gy/minute with single doses of 0, 1, 2, 4, 6, and 8 Gy.
Quantitative survivin TaqMan PCR. Total mRNA from the cell lines was isolated using the RNeasy kit (Qiagen, Hilden, Germany). Survivin mRNA subsequences (77 bp), specific for all three known survivin transcripts, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcripts (63 bp) were amplified from cDNA in duplicate experiments by ready-to-use quantitative PCR assays (Roboscreen, Gesellschaft für molekulare Biotechnologie mbH, Leipzig, Germany). Briefly, conventional 96-well bases were loaded with an 8-well standard DNA strip either coated with different amounts of reference DNA of survivin or GAPDH transcripts, mastermixes containing the primer, and the TaqMan probes. The probes were either 5'-labeled with the fluorescent dye 6-carboxyfluorescein for detection of survivin or VIC for GAPDH, and the common 3'-fluorescent quencher 6-carboxytetra-methylrhodamine. The remaining free positions were loaded with the required number of sample tubes containing just the respective TaqMan oligonucleotide sets. Aliquots of reaction premixes containing PCR buffer supplemented with the dye 6-carboxy-tetramethyl-rhodamin, deoxynucleotide triphosphates, and 1.25 units of AmpliTaq "GOLD" (Applied Biosystems, Foster City, CA) were added to each reaction tube by using a BIOMEK 2000 laboratory workstation (Beckman Instruments, Fullerton, CA). PCR amplification and detection was done with an ABI Prism 7000 sequence detection system (Applied Biosystems). Target cDNA amounts were calculated from the simultaneously processed reference DNA strips. Survivin data were correlated to GAPDH cDNA and are given as zeptomoles [zmol, 10–21] survivin mRNA per attomole [amol, 10–18] of GAPDH mRNA.
Western immunoblotting. For immunoblotting, cells were washed and lysed in radioimmunoprecipitation assay buffer [50 mmol/L Tris (pH 7.4), 150 mmol/L NaCl, 1% Triton X-100, 1% deoxycholate] supplemented with protease inhibitors (1 mmol/L phenylmethylsulfonylfluoride, 10 µg/mL pepstatin, 10 µg/mL aprotinin, and 5 µg/mL leupeptin; all from Sigma, Deisenhofen, Germany). Protein concentrations were determined using the bicinchoninic acid protein assay (Pierce, Rockford, IL). Equal amounts of protein (10 µg) were separated on a 12.5% SDS polyacrylamide gel and transferred to a nitrocellulose membrane (Hybond C, Amersham, Freiburg, Germany). Membranes were blocked in 5% nonfat dry milk in P-BS for 30 minutes at room temperature and probed with rabbit antisurvivin antibodies (dilution, 1:1,000, R&D Systems, Wiesbaden, Germany) overnight at 4°C. Next, membranes were incubated with horseradish peroxidase-linked secondary antibodies (1:200, Dako, Hamburg, Germany) and developed by an enhanced chemoluminescence detection system (ECL, Amersham) and autoradiography (Biomax film, Kodak, Rochester, MN). To confirm equal protein loading, membranes were subsequently reprobed with a 1:2000 dilution of an anti-ß-tubulin antibody (Biozol, Eching, Germany). For densitometric analysis, scanned autoradiographs were quantified using the AIDA software package (Raytest, Straubenstadt, Germany).
Quantification of apoptosis and caspase 3/7 assay. Apoptotic cells were quantified using the terminal-deoxynucleotidyl-transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) technique (in situ cell death detection kit, Boehringer Mannheim, Germany) according to the manufacturer's instructions on a minimum of 1,000 cells fixed by methanol acetate (3:1). Caspase 3/7 activity was measured in a 96-well microplate format using the Apo-ONE assay (Promega, Mannheim, Germany). Cells (1-3 x 105) were incubated for 90 minutes in a luciferase substrate mix and luminescence activity was measured in a luminometer (Berthold, Bad Wildbad, Germany).
3-(4,5-Methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Cells transfected 24 hours previously with either survivin-specific siRNA or GFP-siRNA were seeded at a density of 2 to 10 x 103 cells/200 µL in a 96-well microplate, grown for 6 hours and subsequently exposed to 8 Gy irradiation. After 24, 48, and 72 hours of incubation at 37°C, 3-(4,5-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was added (20 µL/well of a 5 mg/mL solution in PBS) for 4 hours. Solubilization of the converted purple formazan dye was accomplished by adding 50 µL/well of 0.01 N HCl/20% SDS and incubating overnight at 37°C. The reaction product was quantified by measuring the absorbance at 570 nm using an ELISA reader (HTS 7000, Perkin-Elmer, Rodgau, Germany) and Software HT-Soft (Perkin-Elmer). All samples were assayed in triplicate.
Cell cycle analysis. Both adherent and detached SW480 and HCT-15 cells (1 x 106/mL) were collected by trypsinization and washed with PBS for 10 minutes by centrifugation at 120 x g. Cells were resuspended in a staining solution containing 1 µg/mL propidium iodide, 4 mmol/L sodium citrate, 1 mg/mL RNase A (Boehringer Mannheim), and 0.1% Triton X-100. Fluorescence-activated cell sorting analysis was done with a Coulter EPICS flow cytometer XL (Coulter, Hialeah, FL) and data were analyzed using the SystemXL-II software (Coulter). At least three independent experiments, each in duplicate, were done for each set of data.
Flow cytometry for phospho-histone 
H2AX. For the analysis of Ser139-phosphorylated histone H2AX, cells were irradiated with 2 Gy, detached by accutase (PAA, Pasching, Austria) treatment for 15 minutes, pelleted by centrifugation (5 minutes, 120 x g) and fixed in 70% ethanol for 2 hours at –20°C. Before antibody labeling, samples were rehydrated with TBS (pH 7.4), centrifugated and incubated in Tris-buffer, 0.1% Triton X-100 for 10 minutes on ice. Next cells were incubated either with an FITC-conjugated anti-H2AX-antibody at a 1:250 dilution or an isotype control antibody (both Upstate, Lake Placid, NY) for 2 hours in the dark. Cells were fixed in 1% paraformaldehyde in PBS and analyzed using a Coulter EPICS-flow cytometer XL (Coulter). The mean fluorescence of the isotype-control was subtracted to eliminate unspecific background staining for every sample.
Clonogenic survival assay. The clonogenic assay was done on single cell suspension as described previously (7). Following transfection with siRNA, cells were plated in complete DMEM into culture dishes and irradiated as described. After 10 to 14 days, colonies were stained with methylene blue solution for 30 minutes and counted using an automatic colony analyzing machine (ACAM, Erlangen, Germany). Next, calculation of survival fractions (SF) was done using the equation SF = colonies counted / cells seeded x (PE / 100), taking into consideration the individual plating efficiency (PE). Survival variables 
and ß were fitted according to the linear quadratic equation (SF = exp [– x D – ß x D2]) with D = dose using TechPlot-software (TechPlot, Braunschweig, Germany). All experiments were repeated at least thrice. Radiation-induced cytotoxicity enhancement factors at 50% and 10% survival were calculated by transforming the abovementioned equation using and ß values of the individual survival curves.
Preoperative radiochemotherapy protocol. A cohort of 59 patients with locally advanced rectal cancer (International Union Against Cancer stage II and III) received preoperative radiochemotherapy within a prospective protocol (CAO/ARO/AIO-94). All patients received a total dose of 50.4 Gy with daily fractions of 1.8 Gy on 5 consecutive days per week. During the 1st and 5th week of radiotherapy, 5-fluorouracil was delivered concomitantly at a dose of 1,000 mg/m2/day as a 120-hour continuous infusion. Six weeks after completion of preoperative radiochemotherapy, patients were scheduled to undergo surgery. The median follow-up time for these patients was 78.5 months (range, 4.5-120).
Immunohistochemical staining for survivin and quantification of apoptosis on pretreatment biopsies. Immunohistochemical staining for survivin was carried out as previously described (17). Before labeling, deparaffinized tissue sections were overlaid with 10 mmol/L citrate buffer (pH 6.0) and heated for 20 minutes in a pressure cooker. Next, slides were blocked with 5% bovine serum albumin in PBS and primary antibodies (ab469, Abcam, Ltd., Cambridge, United Kingdom) were applied at a 1:50 dilution, followed by an incubation with biotinylated anti-rabbit secondary antibody (Dianova, Hamburg, Germany, at a dilution of 1:50 for 1 hour room temperature) and streptavidin/biotinylated alkaline phosphatase for 30 minutes. Finally Fast-Red solution was used as chromogen and hematoxylin (37%) for counterstaining. Negative control slides in the absence of primary antibodies were included for each staining. The mean percentage of positive tumor cells was determined using an Image System (Optimas 6.2, Stemmer PC Systeme, Puchheim, Germany) and assigned to one of the following categories: 0 (<5%), 1 (5-25%), 2 (25-50%), 3 (50-75%), and 4 (>75%). The intensity of survivin immunostaining was scored as: 1+ (weak), 2+ (moderate), and 3+ (intense). The percentage of positive tumor cells and staining intensity were then multiplied to produce a weighted score for each case ranging from 0 to 12. Because of the limited number of patients and to facilitate further statistical analysis, the weighted survivin score was arbitrarily dichotomized: "low-survivin expression" was classified as a survivin score of 5 or below and "high-survivin expression" as a score of 6 or above.
Apoptotic cancer cells were quantitated using the TUNEL technique (in situ cell death detection kit, Boehringer Mannheim) as described in ref. (5). The apoptotic index was obtained by dividing the number of apoptotic tumor cells by the total number of tumor cells, multiplied by 100. A minimum of 1,000 cells were counted in 10 random regions of the tumor biopsies using a fluorescence microscope (Axiophot, Leitz, Wetzlar, Germany) equipped with a CCD camera and an Image System (Optimas 6.2, Stemmer PC Systeme).
Statistical evaluation. Experimental in vitro data are presented as mean ± SD from three or more independent experiments. Levels of significance for these data were calculated using Student's t test (Excel, Microsoft, Germany). The association of the dichotomized survivin expression with the mean apoptotic index in the pretreatment biopsies of rectal cancer patients was tested using the Mann-Whitney U test for two independent samples. Local failure rates were calculated using the method of Kaplan-Meier, and differences were analyzed with the log-rank test. The level of significance was 0.05 (two-sided) in all statistical testing.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
|
|
H2AX induced by radiation. To analyze whether inhibition of survivin may also affect radioresistance by interaction with repair mechanisms, initial H2AX Ser139 phosphorylation was analyzed. As shown in Fig. 4, induction of phospho-histone H2AX, a marker of recognized DNA double-strand breaks, was increased after survivin siRNA treatment in SW480 cells 20 to 40 minutes after irradiation and remained elevated as compared with GFP- or mock-treated cells.
|
|
|
Survivin expression as a predictor for treatment response to preoperative radiochemotherapy. With a median follow-up of 78 months after preoperative radiochemotherapy and curative resection, the 5-year cumulative incidence of local relapse for the 59 patients was 14%. As shown in Fig. 6, a high-survivin expression was significantly related (P = 0.05) to an increased risk of local relapse as compared with tumors showing low-survivin expression (6% versus 26% at 5 years).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Given such strong evidence implicating survivin's role in enhancing the malignant potential of colorectal cancer, in this study, we investigated whether survivin also plays a direct role in mediating radiation resistance. We showed that attenuation of survivin mRNA (Fig. 1A) and protein (Fig. 1B) expression by siRNA treatment resulted in an increased rate of spontaneous and radiation-induced apoptosis (Fig. 2A) as well as an increased caspase 3/7 activity (Fig. 2B). Transfection with survivin siRNA decreased cell viability (Fig. 3A), and induced a G2-M arrest (Fig. 3B). Moreover, it also increased the DNA double-strand breaks induced by radiation (Fig. 4), and finally resulted in an increased radiosensitivity as determined in the clonogenic assay (Fig. 5). These effects were more pronounced in the radioresistant SW480 cell line with a radiation-induced cytotoxicity enhancement factor at 10% and 50% survival of 1.8 and 2.2, as compared with 1.5 and 1.7 for the intermediately radioresistant HCT-15 cell line (Table 1). Moreover, in our translational study on 59 rectal cancer patients, increased survivin expression was not only inversely related to the number of spontaneous apoptosis in pretreatment biopsies but was also associated with a significant higher risk of local treatment failure after radiochemotherapy (Fig. 6). Thus, survivin expression seemed to be a marker of radiation resistance in vitro, and a predictive factor for radiation response and local control in the clinical setting (17).
Response to radiation is thought to have multifactorial etiologies. The possible underlying mechanisms by which survivin may enhance cell survival upon radiation exposure remain to be elucidated. The conventional notion is that survivin enhances survival of tumor cells primarily through suppression of apoptosis-related cell death, probably via direct inhibition of caspases (21). However, there also seemed to be additional mechanisms. First, we observed that survivin siRNA treatment altered the cell cycle distribution, resulting in an increased G2-M fraction 24 hours after transfection (Fig. 3B). Thus, at the time of irradiation, the cells were blocked in a more radiosensitive stage of the cell cycle. Kappler et al. (22) have also recently shown a marked G2-M arrest, an impaired mitosis, and an increased number of polyploid cells after survivin-specific siRNA treatment in five human sarcoma cell lines. This is in line with our observations of a reduced cell viability in the MTT test (Fig. 3A) and a reduced plating efficiency in the clonogenic assays after survivin siRNA treatment alone (Table 1). Furthermore, we found a higher incidence of DNA double-strand breaks after irradiation, as indicated by a higher amount of Ser139-phoshorylated histone H2AX staining 20 to 360 minutes after survivin siRNA treatment (Fig. 4; ref. 23). Using adenoviral vectors containing a dominant-negative survivin construct, Chakravarti et al. (24) also reported a decreased DNA repair capacity of glioblastoma cells upon radiation exposure as measured by a comet assay. Thus, both the survivin siRNA–induced arrest of cells in the more radiosensitive G2-M phase and the impaired post-irradiation DNA damage repair, may well have contributed to the induction of apoptosis through caspase-dependent or -independent pathways in otherwise resistant tumor cells against radiation. These findings are also in good correlation with the observed reduction in the slope of the survival curve shoulder and the increased ratio of /ß variables, indicative for a reduced sublethal or potentially lethal DNA damage repair in survivin siRNA–treated SW480 and HCT-15 cells after irradiation (Fig. 5; Table 1).
Our results in colorectal cancer are in accordance with reports in other malignancies showing an increased sensitivity of melanoma cells and lung cancer cells to irradiation following attenuation of survivin expression by ribozyme treatment and antisense, respectively (25–27). In this context, it is noteworthy that all the cell lines used within these studies harbor a mutated p53 gene. SW480 is described to harbor a G
A mutation in codon 273 of the p53 gene and a C > T mutation in codon 309 (28); HCT-15 is characterized by a heterozygous wild-type and C > G mutation at codon 153 (29). Therefore, although an interaction of the p53 protein and survivin by direct promoter binding or more indirectly by chromatin deacetylation or enhanced p53 degradation has recently been described (30–32), the radiosensitizing effects of survivin inhibition did not seem to be mediated by wild-type p53. This is of relevance for the clinical setting, as mutated p53, found with a high incidence in rectal cancer, may not interfere with a putative therapeutic intervention of the survivin pathway in combination with radio- and chemotherapy.
In summary, our results suggest that survivin, as determined in pretreatment biopsies, could serve as a predictive factor to identify patients likely to respond to conservative radiotherapies and that gene therapeutic or pharmacological approaches targeting survivin in tumors overexpressing this protein could strongly increase the therapeutic ratio of radiotherapy for rectal cancer. The underlying mechanisms by which antisurvivin strategies may improve radiation response seem to be multifaceted, and involve suppression of caspase-mediated apoptosis as well as alterations in cell cycle distribution and impaired DNA double-strand break repair. Additional studies are ongoing to validate the optimal sequence of siRNA treatment during a fractionated course of radiotherapy in animal models of colorectal cancer.
|
Acknowledgments |
|---|
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.
The authors gratefully acknowledge Dr. Matthias Truss, Pediatric Clinic, University of Berlin, for kindly providing the sequence of survivin-specific siRNA and the excellent technical assistance of R. Sieber and B. Müller. Experiments were performed in part at the Nikolaus-Fiebiger-Center for Molecular Medicine at the University of Erlangen-Nuremberg.
Received 8/20/04. Revised 3/10/05. Accepted 3/17/05.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  S. Konduri, J. Colon, C. H. Baker, S. Safe, J. L. Abbruzzese, A. Abudayyeh, Md. R. Basha, and M. Abdelrahim Tolfenamic acid enhances pancreatic cancer cell and tumor response to radiation therapy by inhibiting survivin protein expression Mol. Cancer Ther., March 1, 2009; 8(3): 533 - 542. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. JIANG, B. REN, L. XU, S. SONG, C. ZHU, and F. YE Survivin May Enhance DNA Double-strand Break Repair Capability by Up-regulating Ku70 in Human KB Cells Anticancer Res, January 1, 2009; 29(1): 223 - 228. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Iwasa, I. Okamoto, M. Suzuki, T. Nakahara, K. Yamanaka, E. Hatashita, Y. Yamada, M. Fukuoka, K. Ono, and K. Nakagawa Radiosensitizing Effect of YM155, a Novel Small-Molecule Survivin Suppressant, in Non-Small Cell Lung Cancer Cell Lines Clin. Cancer Res., October 15, 2008; 14(20): 6496 - 6504. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. B. Kunnumakkara, P. Diagaradjane, S. Guha, A. Deorukhkar, S. Shentu, B. B. Aggarwal, and S. Krishnan Curcumin Sensitizes Human Colorectal Cancer Xenografts in Nude Mice to {gamma}-Radiation by Targeting Nuclear Factor-{kappa}B-Regulated Gene Products Clin. Cancer Res., April 1, 2008; 14(7): 2128 - 2136. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S.-K. Seo, H.-O. Jin, H.-C. Lee, S.-H. Woo, E.-S. Kim, D.-H. Yoo, S.-J. Lee, S. An, C.-H. Rhee, S.-I. Hong, et al. Combined Effects of Sulindac and Suberoylanilide Hydroxamic Acid on Apoptosis Induction in Human Lung Cancer Cells Mol. Pharmacol., March 1, 2008; 73(3): 1005 - 1012. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Lechler, X. Wu, W. Bernhardt, V. Campean, S. Gastiger, T. Hackenbeck, B. Klanke, A. Weidemann, C. Warnecke, K. Amann, et al. The Tumor Gene Survivin Is Highly Expressed in Adult Renal Tubular Cells: Implications for a Pathophysiological Role in the Kidney Am. J. Pathol., November 1, 2007; 171(5): 1483 - 1498. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. de Heer, E. C. de Bruin, E. Klein-Kranenbarg, R. I.J.M. Aalbers, C. A.M. Marijnen, H. Putter, H. J. de Bont, J. F. Nagelkerke, J. H. J.M. van Krieken, H. W. Verspaget, et al. Caspase-3 Activity Predicts Local Recurrence in Rectal Cancer Clin. Cancer Res., October 1, 2007; 13(19): 5810 - 5815. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Pennati, M. Folini, and N. Zaffaroni Targeting survivin in cancer therapy: fulfilled promises and open questions Carcinogenesis, June 1, 2007; 28(6): 1133 - 1139. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. S. Chen, W. A. Woodward, F. Behbod, S. Peddibhotla, M. P. Alfaro, T. A. Buchholz, and J. M. Rosen Wnt/beta-catenin mediates radiation resistance of Sca1+ progenitors in an immortalized mammary gland cell line J. Cell Sci., February 1, 2007; 120(3): 468 - 477. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. K. Knauer, O. H. Kramer, T. Knosel, K. Engels, F. Rodel, A. F. Kovacs, W. Dietmaier, L. Klein-Hitpass, N. Habtemichael, A. Schweitzer, et al. Nuclear export is essential for the tumor-promoting activity of survivin FASEB J, January 1, 2007; 21(1): 207 - 216. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Zhu, L. Gu, H. W. Findley, C. Chen, J.-T. Dong, L. Yang, and M. Zhou KLF5 Interacts with p53 in Regulating Survivin Expression in Acute Lymphoblastic Leukemia J. Biol. Chem., May 26, 2006; 281(21): 14711 - 14718. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Tirro, M. L. Consoli, M. Massimino, L. Manzella, F. Frasca, L. Sciacca, L. Vicari, G. Stassi, L. Messina, A. Messina, et al. Altered Expression of c-IAP1, Survivin, and Smac Contributes to Chemotherapy Resistance in Thyroid Cancer Cells. Cancer Res., April 15, 2006; 66(8): 4263 - 4272. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Lotem, D. Netanely, E. Domany, and L. Sachs Human cancers overexpress genes that are specific to a variety of normal human tissues PNAS, December 20, 2005; 102(51): 18556 - 18561. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Rodel, P. Martus, T. Papadoupolos, L. Fuzesi, M. Klimpfinger, R. Fietkau, T. Liersch, W. Hohenberger, R. Raab, R. Sauer, et al. Prognostic Significance of Tumor Regression After Preoperative Chemoradiotherapy for Rectal Cancer J. Clin. Oncol., December 1, 2005; 23(34): 8688 - 8696. [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 |
