Impact of the adaptor protein GIPC1/Synectin on radioresistance and survival after irradiation of prostate cancer

PURPOSE

Studies have shown that GIPC1/Synectin is an essential adaptor protein of receptors that play an important role in cancer progression and therapy resistance. This is the first study to explore the role of GIPC1/Synectin in radioresistance of prostate cancer and as a possible predictive marker for outcome of primary radiation therapy.

MATERIALS AND METHODS

The effect of RNA interference-mediated GIPC1/Synectin depletion on clonogenic cell survival after irradiation with 0, 2, 4, or 6 Gy was assayed in two different GIPC1/Synectin-expressing human prostate cancer cell lines. The clinical outcome data of 358 men who underwent radiotherapy of prostate cancer with a curative intention were analyzed retrospectively. Uni- and multivariate analysis was performed of prostate-specific antigen recurrence-free survival and overall survival in correlation with protein expression in pretreatment biopsy specimens. Protein expression was evaluated by standard immunohistochemistry methods.

RESULTS

In cell culture experiments, no change was detected in radiosensitivity after depletion of GIPC1/Synectin in GIPC1/Synectin-expressing prostate cancer cell lines. Furthermore, there was no correlation between GIPC1/Synectin expression in human pretreatment biopsy samples and overall or biochemical recurrence-free survival after radiotherapy in a retrospective analysis of the study cohort.

CONCLUSION

Our results do not show a predictive or prognostic function of GIPC1/Synectin expression for the outcome of radiotherapy in prostate cancer. Furthermore, our in vitro results do not support a role of GIPC1 in the cellular radiation response. However, the role of GIPC1 in the progression of prostate cancer and its precursors should be subject to further research.

PARK2 and PACRG are commonly downregulated in clear-cell renal cell carcinoma and are associated with aggressive disease and poor clinical outcome

PARK2 is an E3 ligase, known to be involved in ubiquitination of several proteins and to play a role in neuronal protection. The gene PARK2 and its potentially co-regulated gene PACRG have been previously found to be deleted in clear-cell renal cell carcinomas (ccRCCs). The aim of our study was to evaluate the mRNA and protein expression of PARK2 and PACRG in a large cohort of ccRCC, and to investigate their association with outcome. The expression of both genes was measured by quantitative PCR in 94 primary ccRCCs and autologous nonmalignant kidney tissues. PACRG and PARK2 protein expression was determined immunohistochemically using tissue microarrays comprising 133 ccRCCs. The mRNA and protein expression of PARK2 and PACRG was significantly downregulated in ccRCCs compared with nonmalignant tissues. Low levels of PARK2 mRNA were associated with high-grade ccRCC and lymph node metastasis. Patients with low PARK2 mRNA levels showed a higher tumor-specific mortality rate and a shorter overall survival (OS) than those with high PARK2 expression. Patients without PACRG mRNA expression in the tumor had a shorter disease-free survival and OS than those with tumors expressing PACRG. In multivariate analyses, neither PARK2 nor PACRG expression were independent prognostic factors. The protein expression of PARK2 and PACRG was significantly downregulated in ccRCCs (82.8, and 96.9%, respectively), but no association with clinical outcome was noticed.

[Barrett's esophagus. An update]

Barrett's esophagus (BE), a well-known complication of gastroesophageal reflux disease (GERD), constitutes a precancerous condition for adenocarcinoma of the distal esophagus. The so-called Barrett's carcinoma shows increasing incidences in countries of the western hemisphere; new data, however, indicate that the rise in incidence is not quite as dramatic as previously assumed. The definition of BE is currently changing: despite good reasons for a purely endoscopic definition of BE, goblet cells are still mandatory for this diagnosis in Germany and the USA. Dysplastic changes in the epithelium are the most important risk factor for the development of Barrett's adenocarcinoma and recently dysplasia was subclassified into a more frequent adenomatous (intestinal) and a non-adenomatous (gastric-foveolar) types. The gold standard for diagnosing dysplasia is still H&E staining. The histological diagnosis of dysplasia is still encumbered by a significant interobserver variability, especially regarding the differentiation between low grade dysplasia and inflammatory/reactive changes and the discrimination between high grade dysplasia and adenocarcinoma. Current data, however, show much higher interobserver agreement in endoscopic resection specimens than in biopsies. Nevertheless, the histological diagnosis of dysplasia should be corroborated by an external second opinion because of its clinical consequences. In endoscopic resections of early Barrett's adenocarcinoma, the pathological report has to include a risk stratification for the likelihood of lymphogenic metastases.

Abstract 5526: Lymphangiogenesis in regional lymph nodes is an independent prognostic marker in rectal cancer patients after neoadjuvant treatment

One of the major prognostic factors in rectal cancer is lymph node metastasis. The formation of lymph node metastases is dependent on the existence of a premetastatic niche. An important factor preceding metastasis are lymph vessels which are located in the lymph node. Accordingly, the occurrence of intranodal lymphangiogenesis is thought to indicate distant metastasis and worse prognosis. To evaluate the significance of lymph node lymphangiogenesis, we studied formalin fixed, paraffin embedded adenocarcinomas and regional lymph nodes of 203 rectal cancer patients who were treated with neoadjuvant radiochemotherapy and consecutive surgery. Regional lymph node lymph vessels were detected by immunohistochemistry for podoplanin (D2-40). Our results show that the presence of lymphatic vessels in regional lymph nodes significantly affects the disease-free survival in univariate and multivariate analyses. In contrast, there was no correlation between peritumoral or intratumoral lymph vessel density and prognosis. Indeed, our study demonstrates the importance of lymphangiogenesis in regional lymph nodes after neoadjuvant radiochemotherapy and consecutive surgery as an independent prognostic marker. Staining for intranodal lymphangiogenesis and methods of intravital imaging of lymphangiogenesis and lymphatic flow may be a useful strategy to predict long-term outcome in rectal cancer patients. Furthermore, addition of VEGF-blocking agents to standardized neoadjuvant treatment schemes might be indicated in advanced rectal cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5526. doi:1538-7445.AM2012-5526

[Standardized and structured histopathological evaluation of colorectal polyps: a practical checklist against the background of the new WHO classification]

Gastroenterologists removing colorectal polyps expect standardized and well-structured pathological reports, providing them with all relevant data for the further clinical management of the patient. Over the last year, a task force of clinicians and pathologists has developed a checklist to improve and harmonize endoscopic and pathological reporting of colorectal polyps. This checklist concentrates more on concrete recommendations from evidence-based guidelines and established international classifications for daily practice rather than detailed molecular pathological pathways of carcinogenesis. These recommendations are based on the current S3 guidelines for colorectal cancer (the chapter entitled "Management of colorectal polyps"), the histomorphological consensus manuscript of the GI working group of the German Society for Pathology, as well as the current WHO classification for tumors of the digestive system.

Lymphangiogenesis in regional lymph nodes is an independent prognostic marker in rectal cancer patients after neoadjuvant treatment

One of the major prognostic factors in rectal cancer is lymph node metastasis. The formation of lymph node metastases is dependent on the existence of a premetastatic niche. An important factor preceding metastasis are lymph vessels which are located in the lymph node. Accordingly, the occurrence of intranodal lymphangiogenesis is thought to indicate distant metastasis and worse prognosis. To evaluate the significance of lymph node lymphangiogenesis, we studied formalin fixed, paraffin embedded adenocarcinomas and regional lymph nodes of 203 rectal cancer patients who were treated with neoadjuvant radiochemotherapy and consecutive curative surgery with cancer free surgical margins (R0). Regional lymph node lymph vessels were detected by immunohistochemistry for podoplanin (D2-40). Our results show that the presence of lymphatic vessels in regional lymph nodes significantly affects the disease-free survival in univariate and multivariate analyses. In contrast, there was no correlation between peritumoral or intratumoral lymph vessel density and prognosis. Indeed, our study demonstrates the importance of lymphangiogenesis in regional lymph nodes after neoadjuvant radiochemotherapy and consecutive surgery as an independent prognostic marker. Staining for intranodal lymphangiogenesis and methods of intravital imaging of lymphangiogenesis and lymphatic flow may be a useful strategy to predict long-term outcome in rectal cancer patients. Furthermore, addition of VEGF-blocking agents to standardized neoadjuvant treatment schemes might be indicated in advanced rectal cancer.

[Nonbacterial colitides]

Aside from bacterial infections, viral, fungal, and parasitic infections are important differential diagnoses in inflammatory disorders of the colorectum. In contrast to bacterial infections, in which the causative organism can hardly ever be detected histologically, in non bacterial infections the germs can often be verified by either histology, immunohistochemistry, or at least by molecular pathology. This manuscript will give an overview of the spectrum of pathogenic germs, the clinical symptoms, and pathological findings of the most important infections.

[Bacterial colitis]

The question of whether there are inflammatory changes in colorectal biopsy specimens is frequently asked, especially when the patient reports diarrhea or when the mucosa is reddened on endoscopy. The pathologist first has to find out whether there is, in fact, an increase in the inflammatory infiltrate of the colorectal mucosa which warrants the diagnosis of inflammation. If so, the second challenge is to ascertain the etiology of these inflammatory changes, in particular to differentiate between infectious and non-infectious causes. In principle, we can distinguish forms of colitis with distinct morphological hallmarks confirming the diagnosis (e.g. microscopic detection of the causative organism, as well as lymphocytic or collagenous colitis) from other forms of colitis which have a characteristic pattern of findings not necessarily allowing to deduce the etiology (e.g. infectious colitis without microscopic evidence of the germ vs. inflammatory bowel disease). The present article discusses the pathomorphology and differential diagnosis of the most important forms of bacterial colitis.

[Serrated precursor lesions]

The so-called serrated pathway has in recent years been well established as a second route of colorectal carcinogenesis. Sessile serrated polyps, especially sessile serrated adenomas (SSA) and traditional serrated adenomas (TSA) were identified as precursor lesions of this pathway. Activating mutations in either the BRAF (in SSAs) or the KRAS oncogene (in TSAs) have been determined as the initiating molecular alterations, followed by epigenetic methylation of CpG islands in promoter regions of genes which are implicated in cell cycle control or DNA repair. These findings have led to a paradigm shift in gastrointestinal pathology as lesions without cytological dysplasia, such as SSAs and certain forms of hyperplastic polyps, are now accepted to be precancerous lesions. In addition, carcinomas that have developed through the serrated pathway of colorectal carcinogenesis show varying biological behavior relevant for the clinical management of these tumors depending on the molecular aberrations.

Expression profile of WNT molecules in prostate cancer and its regulation by aminobisphosphonates

Skeletal metastases represent a frequent complication in patients with advanced prostate cancer (PCa) and often require bisphosphonate treatment to limit skeletal-related events. Metastasized PCa cells disturb bone remodeling. Since the WNT signaling pathway regulates bone remodeling and has been implicated in tumor progression and osteomimicry, we analyzed the WNT profile of primary PCa tissues and PCa cell lines and assessed its regulation by bisphosphonates. Prostate tissue (n = 18) was obtained from patients with benign prostate hyperplasia (BPH) and PCa patients with different disease stages. Serum samples were collected from 62 patients. Skeletal metastases were present in 17 patients of whom 6 had been treated with zoledronic acid. The WNT profile and its regulation by bisphoshonates were analyzed in tissue RNA extracts and serum samples as well as in osteotropic (PC3) and non-osteotropic (DU145, LNCaP) PCa cell lines. Several members of the WNT pathway, including WNT5A, FZD5, and DKK1 were highly up-regulated in PCa tissue from patients with advanced PCa. Interestingly, osteotropic cells showed a distinct WNT profile compared to non-osteotropic cells. While WNT5A, FZD5, and DKK1 were highly expressed in PC3 cells, WNT1 and SFRP1 mRNA levels were higher in DU145 cells. Moreover, zoledronic acid down-regulated mRNA levels of WNT5A (-34%), FZD5 (-60%), and DKK1 (-46%) in PC3 cells. Interestingly, patients with skeletal metastases who received zoledronic acid had twofold higher DKK1 serum levels compared to bisphosphonate-naive patients. The WNT signaling pathway is up-regulated in advanced PCa, differentially expressed in osteotropic versus non-osteotropic cells, and is regulated by zoledronic acid.

Isolation of human islets from partially pancreatectomized patients

Investigations into the pathogenesis of type 2 diabetes and islets of Langerhans malfunction ¹ have been hampered by the limited availability of type 2 diabetic islets from organ donors². Here we share our protocol for isolating islets from human pancreatic tissue obtained from type 2 diabetic and non-diabetic patients who have undergone partial pancreatectomy due to different pancreatic diseases (benign or malignant pancreatic tumors, chronic pancreatitis, and common bile duct or duodenal tumors). All patients involved gave their consent to this study, which had also been approved by the local ethics committee. The surgical specimens were immediately delivered to the pathologist who selected soft and healthy appearing pancreatic tissue for islet isolation, retaining the damaged tissue for diagnostic purposes. We found that to isolate more than 1,000 islets, we had to begin with at least 2 g of pancreatic tissue. Also essential to our protocol was to visibly distend the tissue when injecting the enzyme-containing media and subsequently mince it to aid digestion by increasing the surface area.

To extend the applicability of our protocol to include the occasional case in which a large amount (>15g) of human pancreatic tissue is available , we used a Ricordi chamber (50 ml) to digest the tissue. During digestion, we manually shook the Ricordi chamber³ at an intensity that varied by specimen according to its level of tissue fibrosis. A discontinous Ficoll gradient was then used to separate the islets from acinar tissue. We noted that the tissue pellet should be small enough to be homogenously resuspended in Ficoll medium with a density of 1.125 g/ml. After isolation, we cultured the islets under stress free conditions (no shaking or rotation) with 5% CO₂ at 37 °C for at least 48 h in order to facilitate their functional recovery. Widespread application of our protocol and its future improvement could enable the timely harvesting of large quantities of human islets from diabetic and clinically matched non-diabetic subjects, greatly advancing type 2 diabetes research.

Serrated polyps of the colon and rectum (hyperplastic polyps, sessile serrated adenomas, traditional serrated adenomas, and mixed polyps)-proposal for diagnostic criteria

Until recently, two major types of colorectal epithelial polyps were distinguished: the adenoma and the hyperplastic polyp. While adenomas-because of their cytological atypia-were recognized as the precursor lesions for colorectal carcinoma, hyperplastic polyps were perceived as harmless lesions without any potential for malignant progression mainly because hyperplastic polyps are missing cytological atypia. Meanwhile, it is recognized that the lesions, formerly classified as hyperplastic, represent a heterogeneous group of polyps with characteristic serrated morphology some of which exhibit a significant risk of neoplastic progression. These serrated lesions show characteristic epigenetic alterations not commonly seen in colorectal adenomas and progress to colorectal carcinoma via the so-called serrated pathway (CpG-island-methylation-phenotype pathway). This group of polyps is comprised not only of hyperplastic polyps, but also of sessile serrated adenomas, traditional serrated adenomas and mixed polyps, showing serrated and "classical" adenomatous features. Diagnostic criteria and nomenclature for these lesions are not uniform and, therefore, somewhat confusing. In a consensus conference of the Working Group of Gastroenterological Pathology of the German Society of Pathology, standardization of nomenclature and diagnostic criteria as well as recommendations for clinical management of these serrated polyps were formulated and are presented herein.

PINCH1 regulates Akt1 activation and enhances radioresistance by inhibiting PP1alpha

Tumor cell resistance to ionizing radiation and chemotherapy is a major obstacle in cancer therapy. One factor contributing to this is integrin-mediated adhesion to ECM. The adapter protein particularly interesting new cysteine-histidine-rich 1 (PINCH1) is recruited to integrin adhesion sites and promotes cell survival, but the mechanisms underlying this effect are not well understood. Here we have shown that PINCH1 is expressed at elevated levels in human tumors of diverse origins relative to normal tissue. Furthermore, PINCH1 promoted cell survival upon treatment with ionizing radiation in vitro and in vivo by perpetuating Akt1 phosphorylation and activity. Mechanistically, PINCH1 was found to directly bind to protein phosphatase 1alpha (PP1alpha) - an Akt1-regulating protein - and inhibit PP1alpha activity, resulting in increased Akt1 phosphorylation and enhanced radioresistance. Thus, our data suggest that targeting signaling molecules such as PINCH1 that function downstream of focal adhesions (the complexes that mediate tumor cell adhesion to ECM) may overcome radio- and chemoresistance, providing new therapeutic approaches for cancer.

Correlation of centrosomal aberrations with cell differentiation and DNA ploidy in prostate cancer

OBJECTIVE

To analyze the centrosomal abnormalities in correlation with DNA ploidy and clinicopathologic data in prostate cancer.

STUDY DESIGN

Formalin-fixed, paraffin-embedded material from 63 prostate cancers (PCa) and 10 normal control cases were studied. Centrosomal features (number, area and shape) were assessed by immunohistochemistry with a gamma-tubulin monoclonal antibody. For each case centrosomal features were assessed in 100 cells, and the mean and median value was calculated. Statistical analysis was done by Student's t test, Mann-Whitney U test and multivariate analysis. The colocalization of gamma-tubulin and pericentrin at the centrosome was proven by double immunofluorescence staining. The DNA ploidy status was analyzed on Feulgen-stained, disintegrated paraffin sections using the OPTIMAS-based work station (Media Cybernetics, Silver Spring, Maryland, U.S.A.).

RESULTS

PCa cells showed centrosomal aberrations when compared to normal tissue. Poorly differentiated PCa showed more centrosomal abnormalities than well differentiated PCa (p < 0.05). Twenty-seven percent PCa were DNA nondiploid and 73% PCa were DNA diploid, respectively, just as all control specimens. DNA nondiploid status correlates with centrosomal abnormalities (p < 0.05). pT4 tumors showed significantly more centrosomes than pT2 and pT3 tumors (p < 0.05).

CONCLUSION

Changes in centrosome features indicate disturbed centrosome function and are significantly correlated with loss of differentiation in PCa. This is the first image analysis study of centrosome features in PCa, confirming that centrosome defects are involved in the acquisition of chromosomal aberrations in PCa.

Caveolin-1 mediated radioresistance of 3D grown pancreatic cancer cells

BACKGROUND AND PURPOSE

Resistance of pancreatic ductal adenocarcinoma (PDAC) to chemo- and radiotherapy is a major obstacle. The integral membrane protein Caveolin-1 (Cav-1) has been suggested as a potent target in human pancreatic carcinoma cells.

MATERIALS AND METHODS

Human pancreatic tumor cells were examined in a three-dimensional (3D) cell culture model with regard to clonogenic survival, apoptosis, radiogenic DNA-double strand breaks and protein expression and phosphorylation under siRNA-mediated knockdown of Cav-1 without and in combination with irradiation (X-rays, 0-6Gy). Immunohistochemistry was used to assess Cav-1 expression in biopsies from patients with PDAC.

RESULTS

Tumor cells in PDAC showed significantly higher Cav-1 expression relative to tumor stroma. Cav-1 knockdown significantly reduced beta1 integrin expression and Akt phosphorylation, induced Caspase 3- and Caspase 8-dependent apoptosis and enhanced the radiosensitivity of 3D cell cultures. While cell cycling and Cav-1 promoter activity remained stable, Cav-1 knockdown-induced radiosensitization correlated with elevated numbers of residual DNA-double strand breaks.

CONCLUSIONS

Our data strongly support the concept of Cav-1 as a potent target in pancreatic carcinoma cells due to radiosensitization and Cav-1 overexpression in tumor cells of PDAC. 3D cell cultures are powerful and useful tools for the testing of novel targeting strategies to optimize conventional radio- and chemotherapy regimes for PDAC.

Targeting GIPC/synectin in pancreatic cancer inhibits tumor growth

PURPOSE

Various studies have shown the importance of the GAIP interacting protein, COOH-terminus (GIPC, also known as Synectin) as a central adaptor molecule in different signaling pathways and as an important mediator of receptor stability. GIPC/Synectin is associated with different growth-promoting receptors such as insulin-like growth factor receptor I (IGF-IR) and integrins. These interactions were mediated through its PDZ domain. GIPC/Synectin has been shown to be overexpressed in pancreatic and breast cancer. The goal of this study was to show the importance of GIPC/Synectin in pancreatic cancer growth and to evaluate a possible therapeutic strategy by using a GIPC-PDZ domain inhibitor. Furthermore, the effect of targeting GIPC on the IGF-I receptor as one of its associated receptors was tested.

EXPERIMENTAL DESIGN

The in vivo effects of GIPC/Synectin knockdown were studied after lentiviral transduction of luciferase-expressing pancreatic cancer cells with short hairpin RNA against GIPC/Synectin. Additionally, a GIPC-PDZ--targeting peptide was designed. This peptide was tested for its influence on pancreatic cancer growth in vitro and in vivo.

RESULTS

Knockdown of GIPC/Synectin led to a significant inhibition of pancreatic adenocarcinoma growth in an orthotopic mouse model. Additionally, a cell-permeable GIPC-PDZ inhibitor was able to block tumor growth significantly without showing toxicity in a mouse model. Targeting GIPC was accompanied by a significant reduction in IGF-IR expression in pancreatic cancer cells.

CONCLUSIONS

Our findings show that targeting GIPC/Synectin and its PDZ domain inhibits pancreatic carcinoma growth and is a potential strategy for therapeutic intervention of pancreatic cancer.

Who profits from neoadjuvant radiochemotherapy for locally advanced esophageal carcinoma?

BACKGROUND

Patients suffering from locally advanced esophageal carcinoma are generally treated using multimodal therapies. This prospective, non-randomized trial was performed to evaluate the survival benefit of neoadjuvant radiochemotherapy prior to surgery in comparison with surgery only.

PATIENTS & METHODS

Histopathological outcomes and survival were compared between 61 patients who underwent neoadjuvant radiochemotherapy and 64 comparable control patients who had been under-staged. After neoadjuvant therapy, tumor regression was assessed using the method described by Mandard in 1994. Survival curves for the two groups were estimated using the Kaplan-Meier method, and compared with the log-rank test.

RESULTS

Median and 3-year recurrence-free survival for the entire group were 26 months and 39.7%, respectively. The median and 3-year overall survival reached 34 months and 48.1%. Patients who showed complete response to neoadjuvant therapy had significantly improved survival (35 months) compared to patients with residual tumor cells (28 months), patients with tumors unresponsive to radiochemotherapy (22 months), or patients who received surgery only (control group, 29 months). Patients with nodal-negative carcinomas showed significantly longer survival after surgery only and after neoadjuvant therapy compared to patients with lymph node-positive cancers.

CONCLUSIONS

Complete response after neoadjuvant radiochemotherapy is associated with significantly improved survival. Negative nodal status is a major determinant of outcomes following primary operation or neoadjuvant treatment.

Thymidylate synthase genotypes and tumour regression in stage II/III rectal cancer patients after neoadjuvant fluorouracil-based chemoradiation

PURPOSE

According to the CAO-/ARO-/AIO-94 trial of the German Rectal Cancer Study Group, pre-operative 5-fluorouracil (5-FU)-based long-term chemoradiotherapy (CT/RT) is recommended for patients with rectal cancer UICC stage II/III. However, despite the local benefit of neoadjuvant treatment, the overall prognostic value remains uncertain in comparison to adjuvant CT/RT. We assessed the impact of standardized pre-operative CT/RT and intratumoural mRNA levels and polymorphisms of the TS gene on histopathological tumour regression.

PATIENTS AND METHODS

40 patients with rectal cancer UICC stage II/III, receiving pre-operative 5-FU-based CT/RT followed by standardized surgery, including total mesorectal excision, were investigated. TS gene expression and TS polymorphisms of surgical specimens were correlated with the grade of histopathological tumour regression (0-4). Patients achieved regression grades 2-4 were determined as responders.

RESULTS

TS polymorphisms (5'-28bp repeat+G/C SNP and TS1494del6) could be determined in 39/40 (97.5%) and in 38/40 (95%) patients, respectively. Quantification of TS mRNA expression was successful in 36/40 (90%) patients. There was a highly significant linkage disequilibrium between 5'- and 3'-TS polymorphisms (p=0.0013). Interestingly, the majority of patients (82.1%) with 5'-TS genotypes known to be associated with low mRNA expression (2R/2R, 2R/3RC, 3RC/3RC) also possessed the TS1494del6 +6bp/+6bp genotype correlating with high TS mRNA expression. TS1494del6 polymorphism was significantly associated with TS mRNA expression. Patients with TS1494del6 -6bp/-6bp or -6bp/+6bp genotypes showed significantly lower mean TS mRNA expression with 0.55 (range:0.33;0.84) as compared to +6bp homozygotes with a mean expression of 0.90 (range:0.20;1.91) (p=0.025). Furthermore, all patients with TS 3'-UTR -6bp/-6bp or -6bp/+6bp genotype (11/11) were responders as compared to only 20/26 (77%) of patients with TS 3'-UTR +6bp/+6bp genotype (p=0.082). TS 5'-polymorphisms were not associated with neither tumour regression nor gene expression.

CONCLUSION

Our data suggest that the TS1494del6 polymorphism may be an important predictor for histopathological tumour regression in UICC II/III rectal cancer patients receiving neoadjuvant 5-FU-based CT/RT.

Inactivation of AP1 proteins by a nuclear serine protease precedes the onset of radiation-induced fibrosing alveolitis

Radiation-induced lung damage comprises inflammation (alveolitis) as well as disturbed regulation of cell differentiation and proliferation (fibrosis). The transcriptional regulation of this process is poorly understood. One key transcription factor involved in the regulation of proliferation and differentiation is AP1 (activator protein 1). The present study examined changes in the DNA-binding activity of AP1 after irradiation and defined the underlying molecular mechanisms in an animal model. The right lungs of Fischer rats received a single radiation dose of 20 Gy. Lung tissue was tested for AP1 DNA-binding activity, AP1 mRNA, and levels of AP1 proteins as well as for c-Jun specific proteolytic activity. After an initial increase, the AP1 DNA-binding activity was completely lost starting at 5.5 weeks after irradiation, which is 2.5 weeks before the onset of fibrosing alveolitis. This was not caused by reduction of mRNA levels or size. Instead, a selective nuclear cleavage of c-Jun by a serine protease caused the loss of AP1 activity. Considering the central role of AP1 in cell proliferation and differentiation and the strict timely correlation to the onset of the disease, the complete loss of AP1 function is likely to play a critical role in radiation-induced fibrosing alveolitis.