Perioperative LiMAx Test Analysis: Impact of Portal Vein Embolisation, Chemotherapy and Major Liver Resection

BACKGROUND

Postoperative liver failure (PLF) is a severe complication after major liver resection (MLR). To increase the safety of patients, clinical bedside tests are of great importance. However, limitations of their applicability and validity impair their value.

METHODS

Preoperative measurements of the liver maximum capacity (LiMAx) were performed in n = 40 patients, who underwent MLR (≥3 segments). Matched postoperative LiMAx was measured in n = 21 patients. Liver function was compared between pretreated patients (n = 11 with portal vein embolisation (PVE) and n = 19 patients with preoperative chemotherapy) and therapy naïve patients. The LiMAx values were compared with liver-specific blood parameters and volumetric analysis.

RESULTS

In total, n = 40 patients were enrolled in this study. The majority of patients (n = 33; 82.5%) had high preoperative LiMAx values (>315 µg/kg/h), while only seven patients (17.5%) had medium values (140-315 µg/kg/h), and none of the patients had low values (<140 µg/kg/h). A comparison of pretreated patients (with PVE and/or chemotherapy) and therapy naïve patients showed no significant difference in the preoperative LiMAx values (p > 0.05). The preoperative LiMAx values were significantly higher than the matched postoperative values on postoperative day 1 (p < 0.0001). A comparison between the expected and measured postoperative LiMAx showed a difference (≥10%) in 7 out of 13 patients (53.8%). After an initial postoperative decrease in the LiMAx, the patients without complications (n = 12) showed a continuous increase until 14 days after surgery. In the patients with postoperative complications, a decrease in the LiMAx was associated with a prolonged recovery.

CONCLUSIONS

For patients undergoing MLR within the 0.5% rule, which is the clinical gold standard, the LiMAx values do not offer any additional information. Additionally, the LiMAx may have reflected liver function, but it did not deliver additional information regarding postoperative liver recovery. The clinical use of LiMAx might be relevant in selected patients beyond the 0.5% rule.

Combining Surgical Innovations in Amputation Surgery-Robotic Harvest of the Rectus Abdominis Muscle, Transplantation and Targeted Muscle Reinnervation Improves Myocontrol Capability and Pain in a Transradial Amputee

Adding robotic surgery to bionic reconstruction might open a new dimension. The objective was to evaluate if a robotically harvested rectus abdominis (RA) transplant is a feasible procedure to improve soft-tissue coverage at the residual limb (RL) and serve as a recipient for up to three nerves due to its unique architecture and to allow the generation of additional signals for advanced myoelectric prosthesis control. A transradial amputee with insufficient soft-tissue coverage and painful neuromas underwent the interventions and was observed for 18 months. RA muscle was harvested using robotic-assisted surgery and transplanted to the RL, followed by end-to-end neurroraphy to the recipient nerves of the three muscle segments to reanimate radial, median, and ulnar nerve function. The transplanted muscle healed with partial necrosis of the skin mesh graft. Twelve months later, reliable, and spatially well-defined Hoffmann-Tinel signs were detectable at three segments of the RA muscle flap. No donor-site morbidities were present, and EMG activity could be detected in all three muscle segments. The linear discriminant analysis (LDA) classifier could reliably distinguish three classes within 1% error tolerance using only the three electrodes on the muscle transplant and up to five classes outside the muscle transplant. The combination of these surgical procedure advances with emerging (myo-)control technologies can easily be extended to different amputation levels to reduce RL complications and augment control sites with a limited surface area, thus facilitating the usability of advanced myoelectric prostheses.

[Closure of a prostatocutaneous urinary fistula while preserving sexual function using a perineal approach with Gracilis flap interposition]

We present the case of a 36-year-old man suffering from perianal loss of urine through a cutaneous pore while urinating. Appropriate diagnostic investigation showed a urethrocutaneous fistula of the prostatic urethra of unclear aetiology. Because of the patient's young age and sexual activity, surgical treatment was challenging. The fistula was isolated via a perineal access and ligated close to the prostate without endangering the neurovascular bundles. In order to achieve a secure closure of the fistula, a Gracilis flap was placed as an interposition between the dorsal prostate and the percutaneous fistula outlet. To date, no case has been described of a successful, function-preserving surgical treatment of a prostatocutaneous urinary fistula.

Impact of Portal Vein Resection (PVR) in Patients Who Underwent Curative Intended Pancreatic Head Resection

The oncological impact of portal vein resection (PVR) in pancreatic cancer surgery remains contradictory. Different variables might have an impact on the outcome. The aim of the present study is the retrospective assessment of the frequency of PVR, histological confirmation of tumor infiltration, and comparison of oncological outcomes in PVR patients. We retrieved n = 90 patients from a prospectively collected data bank who underwent pancreas surgery between 2012 and 2019 at the University Medical Centre Göttingen (Germany) and showed a histologically confirmed pancreatic ductal adenocarcinoma (PDAC). While 50 patients (55.6%) underwent pancreatic resection combined with PVR, 40 patients (44.4%) received standard pancreatic surgery. Patients with distal pancreatectomy or a tumor other than PDAC were excluded. PVR was performed either as local excision or circular resection of the portal vein. Clinical/patient data and follow-ups were retrieved. The median follow-up period was 20.5 months. Regarding the oncological outcome, a statistically poorer CSS (p = 0.04) was observed in PVR patients. There was no difference (p = 0.18) in patients' outcomes between tangential and complete PVR, while n = 21 (42% of PVR patients) showed portal vein infiltration. The correlation between performed PVR and resection status was statistically significant: 48.6% of PVR patients achieved R0 resections compared to 75% in non-PVR patients (p = 0.03). Patients who underwent PDAC surgery with PVR show a significantly poorer outcome regardless of PVR type. Tumor size and R-status remain two important variables significantly associated with outcome. Since there is a lack of standardization for the indication of PVR, it remains unknown if the need for resection of vein structures during pancreatic resection represents the biological aggressiveness of the tumor or is biased by the experience of the surgeon.

AP1/Fra1 confers resistance to MAPK cascade inhibition in pancreatic cancer

Targeting KRAS downstream signaling remains an important therapeutic approach in pancreatic cancer. We used primary pancreatic ductal epithelial cells and mouse models allowing the conditional expression of oncogenic Kras^G12D, to investigate KRAS signaling integrators. We observed that the AP1 family member FRA1 is tightly linked to the KRAS signal and expressed in pre-malignant lesions and the basal-like subtype of pancreatic cancer. However, genetic-loss-of-function experiments revealed that FRA1 is dispensable for Kras^G12D-induced pancreatic cancer development in mice. Using FRA1 gain- and loss-of-function models in an unbiased drug screen, we observed that FRA1 is a modulator of the responsiveness of pancreatic cancer to inhibitors of the RAF-MEK-ERK cascade. Mechanistically, context-dependent FRA1-associated adaptive rewiring of oncogenic ERK signaling was observed and correlated with sensitivity to inhibitors of canonical KRAS signaling. Furthermore, pharmacological-induced degradation of FRA1 synergizes with MEK inhibitors. Our studies establish FRA1 as a part of the molecular machinery controlling sensitivity to MAPK cascade inhibition allowing the development of mechanism-based therapies.

Dipeptidyl peptidase 9 triggers BRCA2 degradation and promotes DNA damage repair

N-terminal sequences are important sites for post-translational modifications that alter protein localization, activity, and stability. Dipeptidyl peptidase 9 (DPP9) is a serine aminopeptidase with the rare ability to cleave off N-terminal dipeptides with imino acid proline in the second position. Here, we identify the tumor-suppressor BRCA2 as a DPP9 substrate and show this interaction to be induced by DNA damage. We present crystallographic structures documenting intracrystalline enzymatic activity of DPP9, with the N-terminal Met1-Pro2 of a BRCA21-40 peptide captured in its active site. Intriguingly, DPP9-depleted cells are hypersensitive to genotoxic agents and are impaired in the repair of DNA double-strand breaks by homologous recombination. Mechanistically, DPP9 targets BRCA2 for degradation and promotes the formation of RAD51 foci, the downstream function of BRCA2. N-terminal truncation mutants of BRCA2 that mimic a DPP9 product phenocopy reduced BRCA2 stability and rescue RAD51 foci formation in DPP9-deficient cells. Taken together, we present DPP9 as a regulator of BRCA2 stability and propose that by fine-tuning the cellular concentrations of BRCA2, DPP9 alters the BRCA2 interactome, providing a possible explanation for DPP9's role in cancer.

[Intraoperative fluorescence-guided perfusion assessment using indocyanine green-Increased safety in gastrointestinal anastomoses?]

Insufficiency of gastrointestinal anastomoses represents a relevant risk of morbidity and mortality for affected patients. The perfusion quality of the ends of the intestine is the decisive parameter for ensuring sufficient healing of an anastomosis. Intraoperative fluorescence-guided perfusion assessment with indocyanine green is increasingly being used in modern visceral surgery to evaluate tissue perfusion prior to the fashioning of gastrointestinal anastomoses. This technique provides the possibility to distinguish between adequately and inadequately perfused tissue in order to place the anastomosis in the region with the best possible perfusion. Thus, surgeons have a measuring instrument that enables an objective assessment of the perfusion quality of the tissue to be undertaken in addition to a purely subjective macroscopic visual assessment, in order to achieve a better functional result for the patients. Currently, however, the value of this technique has not yet been conclusively clarified. The aim of this review article is to characterize the benefits of intraoperative fluorescence-guided perfusion assessment and to classify it with respect to its significance for routine clinical practice.

Multimodal Treatment of Rectal Cancer

BACKGROUND

Colorectal cancer is one of the three most common types of cancer in Germany. Approximately 30% of these cancers are located in the rectum, corresponding to about 18 000 new cases per year.

METHODS

This review is based on publications retrieved by a selective search in the PubMed database, including current guidelines and recommendations.

RESULTS

Specialized imaging, particularly magnetic resonance imaging, is essential for treatment planning. In very early stages of this disease, tumors without risk factors can be excised locally. Otherwise, radical surgical resection with lymphadenectomy remains the standard treatment, and can be performed either minimally invasive or open. At present, neoadjuvant treatment plans are evolving in the direction of total neoadjuvant therapy. In addition, recent studies investigate whether the improved efficacy of neoadjuvant therapy might now enable patients with a complete clinical remission to be spared from surgical resection (organ-preserving watch-and-wait strategy).

CONCLUSION

The treatment of rectal cancer is a prime example of an interdisciplinary, multimodal approach. In the past, the focus was mainly on improving oncologic outcomes; at present, increasing attention is being devoted to the patients' quality of life as well and the functional aspects of the various modes of treatment.

Gene-expression profiles of pretreatment biopsies predict complete response of rectal cancer patients to preoperative chemoradiotherapy

Purpose

Preoperative (neoadjuvant) chemoradiotherapy (CRT) and total mesorectal excision is the standard treatment for rectal cancer patients (UICC stage II/III). Up to one-third of patients treated with CRT achieve a pathological complete response (pCR). These patients could be spared from surgery and its associated morbidity and mortality, and assigned to a “watch and wait” strategy. However, reliably identifying pCR based on clinical or imaging parameters remains challenging.

Experimental design

We generated gene-expression profiles of 175 patients with locally advanced rectal cancer enrolled in the CAO/ARO/AIO-94 and -04 trials. One hundred and sixty-one samples were used for building, training and validating a predictor of pCR using a machine learning algorithm. The performance of the classifier was validated in three independent cohorts, comprising 76 patients from (i) the CAO/ARO/AIO-94 and -04 trials (n = 14), (ii) a publicly available dataset (n = 38) and (iii) in 24 prospectively collected samples from the TransValid A trial.

Results

A 21-transcript signature yielded the best classification of pCR in 161 patients (Sensitivity: 0.31; AUC: 0.81), when not allowing misclassification of non-complete-responders (False-positive rate = 0). The classifier remained robust when applied to three independent datasets (n = 76).

Conclusion

The classifier can identify >1/3 of rectal cancer patients with a pCR while never classifying patients with an incomplete response as having pCR. Importantly, we could validate this finding in three independent datasets, including a prospectively collected cohort. Therefore, this classifier could help select rectal cancer patients for a “watch and wait” strategy.

Translational relevance

Forgoing surgery with its associated side effects could be an option for rectal cancer patients if the prediction of a pathological complete response (pCR) after preoperative chemoradiotherapy would be possible. Based on gene-expression profiles of 161 patients a classifier was developed and validated in three independent datasets (n = 76), identifying over 1/3 of patients with pCR, while never misclassifying a non-complete-responder. Therefore, the classifier can identify patients suited for “watch and wait”.

Inhibition of Wnt/β-Catenin Signaling Sensitizes Esophageal Cancer Cells to Chemoradiotherapy

The standard treatment of locally advanced esophageal cancer comprises multimodal treatment concepts including preoperative chemoradiotherapy (CRT) followed by radical surgical resection. However, despite intensified treatment approaches, 5-year survival rates are still low. Therefore, new strategies are required to overcome treatment resistance, and to improve patients’ outcome. In this study, we investigated the impact of Wnt/β-catenin signaling on CRT resistance in esophageal cancer cells. Experiments were conducted in adenocarcinoma and squamous cell carcinoma cell lines with varying expression levels of Wnt proteins and Wnt/β-catenin signaling activities. To investigate the effect of Wnt/β-catenin signaling on CRT responsiveness, we genetically or pharmacologically inhibited Wnt/β-catenin signaling. Our experiments revealed that inhibition of Wnt/β-catenin signaling sensitizes cell lines with robust pathway activity to CRT. In conclusion, Wnt/β-catenin activity may guide precision therapies in esophageal carcinoma patients.

Hard wiring of normal tissue-specific chromosome-wide gene expression levels is an additional factor driving cancer type-specific aneuploidies

Background

Many carcinomas have recurrent chromosomal aneuploidies specific to the tissue of tumor origin. The reason for this specificity is not completely understood.

Methods

In this study, we looked at the frequency of chromosomal arm gains and losses in different cancer types from the The Cancer Genome Atlas (TCGA) and compared them to the mean gene expression of each chromosome arm in corresponding normal tissues of origin from the Genotype-Tissue Expression (GTEx) database, in addition to the distribution of tissue-specific oncogenes and tumor suppressors on different chromosome arms.

Results

This analysis revealed a complex picture of factors driving tumor karyotype evolution in which some recurrent chromosomal copy number reflect the chromosome arm-wide gene expression levels of the their normal tissue of tumor origin.

Conclusions

We conclude that the cancer type-specific distribution of chromosomal arm gains and losses is potentially “hardwiring” gene expression levels characteristic of the normal tissue of tumor origin, in addition to broadly modulating the expression of tissue-specific tumor driver genes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-00905-y.

Donor defects after lymph vessel transplantation and free vascularized lymph node transfer: A comparison and evaluation of complications

BACKGROUND

Secondary lymphedema after surgical interventions is a progressive, chronic disease that is still not completely curable. Over the past years, a multitude of surgical therapy options have been described.

AIM

To summarize the single-center complications in lymph vessel (LVTx) and free vascularized lymph node transfer (VLNT).

METHODS

In total, the patient collective consisted of 87 patients who were undergoing treatment for secondary leg lymphedema during the study period from March 2010 to April 2020. The data collection was performed preoperatively during consultations, as well as three weeks, six months and twelve months after surgical treatment. In the event of complications, more detailed follow-up checks were carried out. In total n = 18 robot-assisted omental lymph node transplantations, n = 33 supraclavicular lymph node transplantations and n = 36 Lymph vessel transplantations were analyzed. An exemplary drawing is shown in Figure 1. A graphical representation of patient selection is shown in Figure 2. Robotic harvest was performed with the Da Vinci Xi Robot Systems (Intuitive Surgical, CA, United States).

RESULTS

In total, 11 male and 76 female patients were operated on. The mean age of the patients at study entry was: omental VLNT: 57.45 ± 8.02 years; supraclavicular VLNT: 49.76 ± 4.16 years and LVTx: 49.75 ± 4.95 years. The average observation time postoperative was: omental VLNT: 18 ± 3.48 mo; supraclavicular VLNT: 14.15 ± 4.9 and LVTx: 14.84 ± 4.46 mo. In our omental VLNT, three patients showed a slight abdominal sensation of tension within the first 12 postoperative days. No other donor side morbidities occurred. No intraoperative conversion to open technique was needed. Our supraclavicular VLNT collective showed 10 lift defect morbidities with one necessary surgical intervention. In our LVTx collective, 12 cases of donor side morbidity were registered. In one case, surgical intervention was necessary.

CONCLUSION

Concerning donor side morbidity, robot-assisted omental VLNT is clearly superior to supraclavicular lymph node transplantation and LVTx.

[Human resources management and leadership in surgery]

Due to an increasing lack of qualified personnel, the German healthcare system and especially surgical departments face tremendous challenges. This shortage of qualified personnel not only results in constraints in the provision of patient care but also has a negative impact on the health of available personnel, as these are by default expected to fill the gap. The situation is aggravated by demands and expectations of the younger generation of employees, who are particularly concerned with key topics, such as leadership, working hours and work-life balance. This transformation will inevitably necessitate both chief surgeons and hospital management to re-evaluate and adapt their strategies in order to retain full operability and high quality of medical care of clinics in the future. The objective of this article is to provide a personal assessment of the current and future situation in surgical clinics in Germany with a focus on human resources and leadership.

KRAS mutation status concordance between the primary tumor and the corresponding metastasis in patients with rectal cancer

INTRODUCTION

Oncogenic mutation within the KRAS gene represents a negative predictor for treatment response to anti-epidermal growth factor receptor (EGFR) in patients with colorectal cancer. Recently, we have shown no relevant heterogeneity for KRAS mutation status within and between pre- and posttherapeutic samples from the primary tumor in patients with locally advanced rectal cancer. The aim of this study was to evaluate the intertumoral heterogeneity of KRAS mutation status between the primary tumor and the corresponding metastasis or local recurrence in the similar cohort and to evaluate the ideal representative tissue for KRAS mutation testing.

MATERIALS AND METHODS

KRAS mutation status was analyzed from 47 patients with locally advanced rectal cancer, which were enrolled in the CAO/ARO/AIO-94 or CAO/ARO/AIO-04 trial. Mutations in KRAS codons 12, 13, and 61 were analyzed by using the KRAS RGQ PCR Kit (therascreen® KRAS test). Six patients needed to be excluded due to incomplete follow up data. 11 patients showed a relapse of the disease during the follow up presented by distant metastases or local recurrence. DNA from representative areas of metastatic tissue was obtained from formalin-fixed paraffin-embedded specimens.

RESULTS

The mean patient age was 64.13 ± 10.64 years. In total, 19 patients showed a KRAS mutation (46.34%) in the primary tumor. Of the eleven patients with a metastatic disease or local recurrence, five patients showed a KRAS mutation whereas six patients had a KRAS wildtype status. Metastatic localizations included the liver (n = 2), lung (n = 4), local recurrence (n = 1), liver + lung (n = 3), lung + local recurrence (n = 1). For these eleven patients with paired data available for the primary tumor and metastatic tissue, a significant KRAS mutation status concordance was detected in 81.18% (9/11) of the patients (p = 0.03271). Only two patients showed intertumoral heterogeneity, which harbored in one patient a KRAS G12C mutation status in the primary tumor, but a G12V KRAS mutation status in the corresponding lung lesion, and in the other patient a G12A mutation in the primary lesion and a WT in the lung metastasis.

CONCLUSIONS

We show a significant concordance of the KRAS mutation status between tumor samples obtained from the primary tumor and the corresponding metastasis and/ or local recurrence in patients with rectal cancer indicating no relevant intertumoral heterogeneity. Our data suggest that sampling either the primary (pre- or posttherapeutical tumor tissue) or metastatic lesion may be valid for the initial evaluation of KRAS mutation status predicting the response to anti-EGFR treatment and guiding clinical decisions.

LEF1 supports metastatic brain colonization by regulating glutathione metabolism and increasing ROS resistance in breast cancer

More than half of all brain metastases show infiltrating rather than displacing growth at the macro-metastasis/organ parenchyma interface (MMPI), a finding associated with shorter survival. The lymphoid enhancer-binding factor-1 (LEF1) is an epithelial-mesenchymal transition (EMT) transcription factor that is commonly overexpressed in brain-colonizing cancer cells. Here, we overexpressed LEF1 in an in vivo breast cancer brain colonization model. It shortened survival, albeit without engaging EMT at the MMPI. By differential proteome analysis, we identified a novel function of LEF1 as a regulator of the glutathione (GSH) system, the principal cellular redox buffer. LEF1 overexpression also conferred resistance against therapeutic GSH depletion during brain colonization and improved management of intracellular ROS. We conclude that besides EMT, LEF1 facilitates metastasis by improving the antioxidative capacity of epithelial breast cancer cells, in particular during colonization of the brain parenchyma.

Combined targeting of HER-2 and HER-3 represents a promising therapeutic strategy in colorectal cancer

Background

Abrogation of growth factor-dependent signaling represents an effective therapeutic strategy for patients with colorectal cancer (CRC). Here we evaluated the effectiveness of targeting the epidermal growth factor (EGF) receptors HER-2 and HER-3 in the three cell lines LS513, LS1034 and SW837.

Methods

Treatment with HER-2-specific antibodies trastuzumab and pertuzumab resulted in a mild reduction of cellular viability. In contrast, the antibody-drug conjugate T-DM1 mediated a strong and dose-dependent decrease of viability and Akt phosphorylation.

Results

The most striking effects were observed with the dual tyrosine kinase inhibitor lapatinib, and the Pan-ErbB inhibitor afatinib. Selectively, the effect of EGF receptor inhibition was augmented by a combination with 5-fluorouracil and oxaliplatin. Finally, high expression of HER-3 was detected in 121 of 172 locally advanced rectal cancers (70.3%). In conclusion, inhibition of EGF receptors effectively blocks downstream signaling and significantly impairs viability of CRC cells. However, the effectiveness of receptor inhibition highly depends on the inhibitors’ mode of action, as targeting HER-2 alone is not sufficient.

Conclusion

Since HER-2 and HER-3 are expressed in a relevant number of patients, targeting both receptors may represent a promising therapeutic strategy for CRC.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-6051-0) contains supplementary material, which is available to authorized users.

Epigenome Mapping Identifies Tumor-Specific Gene Expression in Primary Rectal Cancer

Epigenetic alterations play a central role in cancer development and progression. The acetylation of histone 3 at lysine 27 (H3K27ac) specifically marks active genes. While chromatin immunoprecipitation (ChIP) followed by next-generation sequencing (ChIP-seq) analyses are commonly performed in cell lines, only limited data are available from primary tumors. We therefore examined whether cancer-specific alterations in H3K27ac occupancy can be identified in primary rectal cancer. Tissue samples from primary rectal cancer and matched mucosa were obtained. ChIP-seq for H3K27ac was performed and differentially occupied regions were identified. The expression of selected genes displaying differential occupancy between tumor and mucosa were examined in gene expression data from an independent patient cohort. Differential expression of four proteins was further examined by immunohistochemistry. ChIP-seq for H3K27ac in primary rectal cancer and matched mucosa was successfully performed and revealed differential binding on 44 regions. This led to the identification of genes with increased H3K27ac, i.e., RIPK2, FOXQ1, KRT23, and EPHX4, which were also highly upregulated in primary rectal cancer in an independent dataset. The increased expression of these four proteins was confirmed by immunohistochemistry. This study demonstrates the feasibility of ChIP-seq-based epigenome mapping of primary rectal cancer and confirms the value of H3K27ac occupancy to predict gene expression differences.

ARID1A facilitates KRAS signaling-regulated enhancer activity in an AP1-dependent manner in colorectal cancer cells

Background

ARID1A (AT-rich interactive domain-containing protein 1A) is a subunit of the BAF chromatin remodeling complex and plays roles in transcriptional regulation and DNA damage response. Mutations in ARID1A that lead to inactivation or loss of expression are frequent and widespread across many cancer types including colorectal cancer (CRC). A tumor suppressor role of ARID1A has been established in a number of tumor types including CRC where the genetic inactivation of Arid1a alone led to the formation of invasive colorectal adenocarcinomas in mice. Mechanistically, ARID1A has been described to largely function through the regulation of enhancer activity.

Methods

To mimic ARID1A-deficient colorectal cancer, we used CRISPR/Cas9-mediated gene editing to inactivate the ARID1A gene in established colorectal cancer cell lines. We integrated gene expression analyses with genome-wide ARID1A occupancy and epigenomic mapping data to decipher ARID1A-dependent transcriptional regulatory mechanisms.

Results

Interestingly, we found that CRC cell lines harboring KRAS mutations are critically dependent on ARID1A function. In the absence of ARID1A, proliferation of these cell lines is severely impaired, suggesting an essential role for ARID1A in this context. Mechanistically, we showed that ARID1A acts as a co-factor at enhancers occupied by AP1 transcription factors acting downstream of the MEK/ERK pathway. Consistently, loss of ARID1A led to a disruption of KRAS/AP1-dependent enhancer activity, accompanied by a downregulation of expression of the associated target genes.

Conclusions

We identify a previously unknown context-dependent tumor-supporting function of ARID1A in CRC downstream of KRAS signaling. Upon the loss of ARID1A in KRAS-mutated cells, enhancers that are co-occupied by ARID1A and the AP1 transcription factors become inactive, thereby leading to decreased target gene expression. Thus, targeting of the BAF complex in KRAS-mutated CRC may offer a unique, previously unknown, context-dependent therapeutic option in CRC.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0690-5) contains supplementary material, which is available to authorized users.

Colorectal cancer susceptibility loci as predictive markers of rectal cancer prognosis after surgery

To understand the molecular mechanism of rectal cancer and develop markers for disease prognostication, we generated and explored a dataset from 243 rectal cancer patients by gene expression microarray analysis of cancer samples and matched controls, and SNP-arrays of germline DNA. We found that two of the loci most strongly linked with colorectal cancer (CRC) risk, 8q24 (upstream of MYC) and 18q21 (in the intron of SMAD7), as well as 20q13 (in the intron of LAMA5), are tightly associated with the prognosis of rectal cancer patients. For SNPs on 18q21 (rs12953717 and rs4464148) and 20q13 (rs4925386), alleles that correlate with higher risk for the development of CRC are associated with shorter disease free survival (DFS). However, for rs6983267 on 8q24, the low risk allele is associated with a higher risk for recurrence and metastasis after surgery, and importantly, is strongly correlated with the resistance of CRC cell lines to chemoradiotherapy (CRT). We also found that although MYC expression is dramatically increased in cancer, patients with higher levels of MYC have a better prognosis. The expression of SMAD7 is weakly correlated with DFS. Notably, the presence of the 8q24 and 18q21 SNP alleles is not correlated with expression levels of MYC and SMAD7. rs4464148, and probably rs6983267 and rs4925386, are linked with overall survival time of patients. In conclusion, we show that several CRC risk SNPs detect subpopulations of rectal cancer patients with poor prognosis, and that rs6983267 probably affects prognosis through interfering with the resistance of cancer cells to CRT.

A case report of delayed intra-abdominal and intra-luminal haemorrhage after polypectomy

We report the case of a 70-year-old man who presented with hematochezia, anaemia, and severe abdominal pain 6 days after polypectomy. Contrast-enhanced ultrasound and computed tomography revealed no signs of free intra-abdominal air but showed intra-abdominal and intra-luminal bleeding. The patient was referred to colonoscopy in the operation room, which showed a coagula and venous bleeding at the polypectomy site. Emergency laparotomy was performed and revealed a large intra-abdominal mesocolic hematoma, which was surgically removed. The patient's post-operative recovery was uneventful. While few reports of splenic vessel rupture after colonoscopy due to traction on the splenocolic ligament have been published, delayed mesocolic hematoma without evidence of organ damage has not been reported so far. Clinicians need to be aware of these rare but life-threatening complications following colonoscopy.

Chemoradiotherapy Resistance in Colorectal Cancer Cells is Mediated by Wnt/β-catenin Signaling

Activation of Wnt/β-catenin signaling plays a central role in the development and progression of colorectal cancer. The Wnt-transcription factor, TCF7L2, is overexpressed in primary rectal cancers that are resistant to chemoradiotherapy and TCF7L2 mediates resistance to chemoradiotherapy. However, it is unclear whether the resistance is mediated by a TCF7L2 inherent mechanism or Wnt/β-catenin signaling in general. Here, inhibition of β-catenin by siRNAs or a small-molecule inhibitor (XAV-939) resulted in sensitization of colorectal cancer cells to chemoradiotherapy. To investigate the potential role of Wnt/β-catenin signaling in controlling therapeutic responsiveness, nontumorigenic RPE-1 cells were stimulated with Wnt-3a, a physiologic ligand of Frizzled receptors, which increased resistance to chemoradiotherapy. This effect could be recapitulated by overexpression of a degradation-resistant mutant of β-catenin (S33Y), also boosting resistance of RPE-1 cells to chemoradiotherapy, which was, conversely, abrogated by siRNA-mediated silencing of β-catenin. Consistent with these findings, higher expression levels of active β-catenin were observed as well as increased TCF/LEF reporter activity in SW1463 cells that evolved radiation resistance due to repeated radiation treatment. Global gene expression profiling identified several altered pathways, including PPAR signaling and other metabolic pathways, associated with cellular response to radiation. In summary, aberrant activation of Wnt/β-catenin signaling not only regulates the development and progression of colorectal cancer, but also mediates resistance of rectal cancers to chemoradiotherapy.Implications: Targeting Wnt/β-catenin signaling or one of the downstream pathways represents a promising strategy to increase response to chemoradiotherapy. Mol Cancer Res; 15(11); 1481-90. ©2017 AACR.

Context-Dependent Epigenetic Regulation of Nuclear Factor of Activated T Cells 1 in Pancreatic Plasticity

BACKGROUND & AIMS

The ability of exocrine pancreatic cells to change the cellular phenotype is required for tissue regeneration upon injury, but also contributes to their malignant transformation and tumor progression. We investigated context-dependent signaling and transcription mechanisms that determine pancreatic cell fate decisions toward regeneration and malignancy. In particular, we studied the function and regulation of the inflammatory transcription factor nuclear factor of activated T cells 1 (NFATC1) in pancreatic cell plasticity and tissue adaptation.

METHODS

We analyzed cell plasticity during pancreatic regeneration and transformation in mice with pancreas-specific expression of a constitutively active form of NFATC1, or depletion of enhancer of zeste 2 homologue 2 (EZH2), in the context of wild-type or constitutively activate Kras, respectively. Acute and chronic pancreatitis were induced by intraperitoneal injection of caerulein. EZH2-dependent regulation of NFATC1 expression was studied in mouse in human pancreatic tissue and cells by immunohistochemistry, immunoblotting, and quantitative reverse transcription polymerase chain reaction. We used genetic and pharmacologic approaches of EZH2 and NFATC1 inhibition to study the consequences of pathway disruption on pancreatic morphology and function. Epigenetic modifications on the NFATC1 gene were investigated by chromatin immunoprecipitation assays.

RESULTS

NFATC1 was rapidly and transiently induced in early adaptation to acinar cell injury in human samples and in mice, where it promoted acinar cell transdifferentiation and blocked proliferation of metaplastic pancreatic cells. However, in late stages of regeneration, Nfatc1 was epigenetically silenced by EZH2-dependent histone methylation, to enable acinar cell redifferentiation and prevent organ atrophy and exocrine insufficiency. In contrast, oncogenic activation of KRAS signaling in pancreatic ductal adenocarcinoma cells reversed the EZH2-dependent effects on the NFATC1 gene and was required for EZH2-mediated transcriptional activation of NFATC1.

CONCLUSIONS

In studies of human and mouse pancreatic cells and tissue, we identified context-specific epigenetic regulation of NFATc1 activity as an important mechanism of pancreatic cell plasticity. Inhibitors of EZH2 might therefore interfere with oncogenic activity of NFATC1 and be used in treatment of pancreatic ductal adenocarcinoma.

Loss of CHD1 causes DNA repair defects and enhances prostate cancer therapeutic responsiveness

The CHD1 gene, encoding the chromo-domain helicase DNA-binding protein-1, is one of the most frequently deleted genes in prostate cancer. Here, we examined the role of CHD1 in DNA double-strand break (DSB) repair in prostate cancer cells. We show that CHD1 is required for the recruitment of CtIP to chromatin and subsequent end resection during DNA DSB repair. Our data support a role for CHD1 in opening the chromatin around the DSB to facilitate the recruitment of homologous recombination (HR) proteins. Consequently, depletion of CHD1 specifically affects HR-mediated DNA repair but not non-homologous end joining. Together, we provide evidence for a previously unknown role of CHD1 in DNA DSB repair via HR and show that CHD1 depletion sensitizes cells to PARP inhibitors, which has potential therapeutic relevance. Our findings suggest that CHD1 deletion, like BRCA1/2 mutation in ovarian cancer, may serve as a marker for prostate cancer patient stratification and the utilization of targeted therapies such as PARP inhibitors, which specifically target tumors with HR defects.

Abstract 1653: A novel role for Wnt/β-catenin signaling in mediating resistance of colorectal cancer to chemoradiotherapy

Background: Preoperative chemoradiotherapy represents the standard treatment for patients with rectal cancer. However, the clinical response of individual tumors to multimodal treatment is not uniform, and ranges from complete response to complete resistance. Therefore, the identification of novel therapeutic targets whose modification could be harnessed to sensitize a priori resistant tumors is exceedingly important. Previously, we demonstrated that the Wnt transcription factor TCF7L2 (also known as TCF4) was overexpressed in primary rectal cancers that were resistant to chemoradiotherapy (CRT), and that TCF7L2 functionally mediates resistance of CRC cells to clinically relevant doses of ionizing radiation (IR).

Methods: Using siRNAs we silenced CTNNB1 (β-catenin), another key-component of canonical Wnt-signaling, in colorectal cancer cell lines LS1034, SW480, and SW837. To asses influence on CRT, cells were exposed to 0, 1, 2, 4, 6 and 8 Gy of X-rays and 5-FU. Wnt- signaling was stimulated in retinal pigment epithelial cells (RPE) either by adding Wnt-3A, or overexpressing non degradable β-catenin (S33Y-mutated) and analyzed changes in CRT. Finally we repetitively irradiated SW1463 (68Gy) to establish an isogenic radio-resistant cell line and examined changes in protein expression.

Results: Silencing of CTNNB1 resulted in (chemo-) radiation-sensitization of all three CRC-cell lines. To further investigate the potential role of Wnt/β-catenin signaling in controlling therapeutic responsiveness, non-tumorigenic RPE cells were stimulated with Wnt-3A, which significantly increased resistance to CRT. This effect could be recapitulated by overexpression of β-catenin (S33Y-mutated), resulting in a significantly increased resistance to CRT. The effect could be rescued by siRNA mediated knockdown of β-catenin. Consistent with these findings, we observed higher expression levels of active (unphosphorylated) β-catenin as well as increased TCF reporter activity in SW1463 cells that were rendered radiation-resistant due to repeated IR treatment.

Conclusion: Together, these findings strongly support the interpretation that Wnt/β-catenin signaling plays a central role in mediating resistance of CRC cells to CRT. Hence, pathway inhibition may represent a promising strategy to increase therapeutic responsiveness to CRT, which represents the standard treatment for locally advanced rectal cancers. This would have considerable clinical implications.

Citation Format: Georg Emons, Melanie Spitzner, Sebastian Reineke, Frank Kramer, Margret Rave-Fraenk, Jochen Gaedcke, Michael Ghadimi, Thomas Ried, Marian Grade. A novel role for Wnt/β-catenin signaling in mediating resistance of colorectal cancer to chemoradiotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1653.

Prognostic Value of MicroRNAs in Preoperative Treated Rectal Cancer

Background: Patients with locally advanced rectal cancer are treated with preoperative chemoradiotherapy followed by surgical resection. Despite similar clinical parameters (uT2-3, uN+) and standard therapy, patients’ prognoses differ widely. A possible prediction of prognosis through microRNAs as biomarkers out of treatment-naïve biopsies would allow individualized therapy options. Methods: Microarray analysis of 45 microdissected preoperative biopsies from patients with rectal cancer was performed to identify potential microRNAs to predict overall survival, disease-free survival, cancer-specific survival, distant-metastasis-free survival, tumor regression grade, or nodal stage. Quantitative real-time polymerase chain reaction (qPCR) was performed on an independent set of 147 rectal cancer patients to validate relevant miRNAs. Results: In the microarray screen, 14 microRNAs were significantly correlated to overall survival. Five microRNAs were included from previous work. Finally, 19 miRNAs were evaluated by qPCR. miR-515-5p, miR-573, miR-579 and miR-802 demonstrated significant correlation with overall survival and cancer-specific survival (p < 0.05). miR-573 was also significantly correlated with the tumor regression grade after preoperative chemoradiotherapy. miR-133b showed a significant correlation with distant-metastasis-free survival. miR-146b expression levels showed a significant correlation with nodal stage. Conclusion: Specific microRNAs can be used as biomarkers to predict prognosis of patients with rectal cancer and possibly stratify patients’ therapy if validated in a prospective study.

[Robotic Rectal Cancer Surgery]

BACKGROUND

The oncological outcome of patients with rectal cancer has improved considerably over the past few decades. This is mainly due to the introduction of the surgical concept of total mesorectal excision (TME) and the implementation of multimodal treatment strategies. Additionally, it has recently been demonstrated that the oncological results of open and laparoscopic TME are comparable. For some time there has been an ongoing debate on the potential relevance of robotic assistance systems in visceral surgery. The aim of this study was to evaluate the operative and perioperative outcomes of patients with rectal or rectosigmoid cancer, who were operated on using the Da Vinci Surgical System.

PATIENTS AND RESULTS

We retrospectively analysed the outcomes of 202 consecutive patients, who were operated between September 2010 and November 2015 in three Surgical Centers. The cohort consisted of 136 men and 66 women with a mean BMI of 28. We performed the following procedures: 49 anterior rectal resections, 119 low anterior rectal resections, and 34 abdominoperineal excisions. Conversion to an open procedure was required in 13 patients. Non-surgical complications (n = 27) occurred in 24 patients (12%) and surgical complications (n = 67) in 62 patients (31%). Most complications were due to abdominal or sacral wound infections (n = 25) and anastomotic leaks (n = 18). The mortality rate within 30 days was 2%. The rate of R0 resections was 95%, with circumferential resection margins being negative in 98% of the patients. The quality of the mesorectal resection was scored as good in 91% of the patients.

CONCLUSIONS

The Da Vinci Surgical System can be used safely and with a low complication rate for surgical treatment of rectal cancer. While primary evidence suggests that the outcome of robotic-assisted surgery is comparable with open and laparoscopic surgery, its definitive value has to be determined upon publication of the prospective randomized ROLARR trial. The main advantages of the Da Vinci system are its endowristed instruments with multiple degrees of freedom and its optimised visualisation (3D, stable camera platform controlled by the surgeon). Another positive feature is the significant ergonomic advantage for the surgeon.

Heterogeneity of KRAS Mutation Status in Rectal Cancer

INTRODUCTION

Anti-EGFR targeted therapy is of increasing importance in advanced colorectal cancer and prior KRAS mutation testing is mandatory for therapy. However, at which occasions this should be performed is still under debate. We aimed to assess in patients with locally advanced rectal cancer whether there is intra-specimen KRAS heterogeneity prior to and upon preoperative chemoradiotherapy (CRT), and if there are any changes in KRAS mutation status due to this intervention.

MATERIALS AND METHODS

KRAS mutation status analyses were performed in 199 tumor samples from 47 patients with rectal cancer. To evaluate the heterogeneity between different tumor areas within the same tumor prior to preoperative CRT, 114 biopsies from 34 patients (mean 3 biopsies per patient) were analyzed (pre-therapeutic intratumoral heterogeneity). For the assessment of heterogeneity after CRT residual tumor tissue (85 samples) from 12 patients (mean 4.2 tissue samples per patient) were analyzed (post-therapeutic intratumoral heterogeneity) and assessment of heterogeneity before and after CRT was evaluated in corresponding patient samples (interventional heterogeneity). Primer extension method (SNaPshot™) was used for initial KRAS mutation status testing for Codon 12, 13, 61, and 146. Discordant results by this method were reevaluated by using the FDA-approved KRAS Pyro Kit 24, V1 and the RAS Extension Pyro Kit 24, V1 Kit (therascreen® KRAS test).

RESULTS

For 20 (43%) out of the 47 patients, a KRAS mutation was detected. With 12 out of 20, the majority of these mutations affected codon 35. We did not obtained evidence that CRT results in changes of the KRAS mutation pattern. In addition, no intratumoral heterogeneity in the KRAS mutational status could be proven. This was true for both the biopsies prior to CRT and the resection specimens thereafter. The discrepancy observed in some samples when using the SNaPshot™ assay was due to insufficient sensitivity of this technique upon massive tumor regression by CRT as application of the therascreen® KRAS test revealed concordant results.

CONCLUSION

Our results indicate that the KRAS mutation status at the primary tumor site of rectal cancer is homogenous. Its assessment for therapeutic decisions is feasible in pre-therapeutic biopsies as well as in post-therapeutic resected specimens. The amount of viable tumor cells seems to be an important determinant for assay sensitivity and should thus be considered for selection of the analytical method.

Histone Chaperone SSRP1 is Essential for Wnt Signaling Pathway Activity During Osteoblast Differentiation

Cellular differentiation is accompanied by dramatic changes in chromatin structure which direct the activation of lineage-specific transcriptional programs. Structure-specific recognition protein-1 (SSRP1) is a histone chaperone which is important for chromatin-associated processes such as transcription, DNA replication and repair. Since the function of SSRP1 during cell differentiation remains unclear, we investigated its potential role in controlling lineage determination. Depletion of SSRP1 in human mesenchymal stem cells elicited lineage-specific effects by increasing expression of adipocyte-specific genes and decreasing the expression of osteoblast-specific genes. Consistent with a role in controlling lineage specification, transcriptome-wide RNA-sequencing following SSRP1 depletion and the induction of osteoblast differentiation revealed a specific decrease in the expression of genes involved in biological processes related to osteoblast differentiation. Importantly, we observed a specific downregulation of target genes of the canonical Wnt signaling pathway, which was accompanied by decreased nuclear localization of active β-catenin. Together our data uncover a previously unknown role for SSRP1 in promoting the activation of the Wnt signaling pathway activity during cellular differentiation. Stem Cells 2016;34:1369-1376.

Patterns of Chromosomal Aberrations in Solid Tumors

Chromosomal abnormalities are a defining feature of solid tumors. Such cytogenetic alterations are mainly classified into structural chromosomal aberrations and copy number alterations, giving rise to aneuploid karyotypes. The increasing detection of these genetic changes allowed the description of specific tumor entities and the associated patterns of gene expression. In fact, tumor-specific landscapes of gross genomic copy number changes, including aneuploidies of entire chromosome arms and chromosomes result in a global deregulation of the transcriptome of cancer cells. Furthermore, the molecular characterization of cytogenetic abnormalities has provided insights into the mechanisms of tumorigenesis and has, in a few instances, led to the clinical implementation of effective diagnostic and prognostic tools, as well as treatment strategies that target a specific genetic abnormality.

Preliminary results of the global audit of treatment of refractory status epilepticus

The treatment of refractory and super refractory status epilepticus is a "terra incognita" from the point of view of evidence-based medicine. As randomized or controlled studies that are sufficiently powered are not feasible in relation to the many therapies and treatment approaches available, we carried out an online multinational audit (registry) in which neurologists or intensivists caring for patients with status epilepticus may prospectively enter patients who required general anesthesia to control the status epilepticus (SE). To date, 488 cases from 44 different countries have been collected. Most of the patients had no history of epilepsy and had a cryptogenic etiology. First-line treatment was delayed and not in line with current guidelines. The most widely used anesthetic of first choice was midazolam (59%), followed by propofol and barbiturates. Ketamine was used in most severe cases. Other therapies were administered in 35% of the cases, mainly steroids and immunotherapy. Seizure control was achieved in 74% of the patients. Twenty-two percent of patients died during treatment, and four percent had treatment actively withdrawn because of an anticipated poor outcome. The neurological outcome was good in 36% and poor in 39.3% of cases, while 25% died during hospitalization. Factors that positively influenced outcome were younger age, history of epilepsy, and low number of different anesthetics tried. This article is part of a Special Issue entitled "Status Epilepticus".

Abstract 3946: Wnt/ß-catenin signaling mediates resistance of colorectal cancer cells to chemoradiotherapy

Background: Preoperative chemoradiotherapy represents the standard treatment for patients with rectal cancer. However, the clinical response of individual tumors to multimodal treatment is not uniform, and ranges from complete response to complete resistance. Therefore, the identification of novel therapeutic targets whose modification could be harnessed to sensitize a priori resistant tumors is exceedingly important. In this context, we have previously demonstrated that the Wnt transcription factor TCF4 was over-expressed in rectal cancers that were resistant to chemoradiotherapy. The aim of this study was to explore the functional relevance of TCF4 and Wnt/β-catenin signaling for mediating treatment resistance.

Methods: Colorectal cancer cell lines SW837, SW480, and HT-29 were transfected with shRNAs targeting TCF4. After establishing stable single-cell clone (SCC) populations, selected clones were irradiated at 0, 1, 2, 4, 6 and 8 Gy of X-rays. To assess the putative Wnt/β-catenin dependency, β-catenin was inhibited in cancer cell lines using siRNAs, the tankyrase inhibitors XAV939 / JW55 and the porcupine inhibitor LGK 974. Furthermore Wnt/β-catenin signaling activity was stimulated in normal retinal pigment epithelial (RPE) cells through incubation with Wnt3a.

Results: RNAi-mediated silencing of TCF4 led to a significant radiosensitization in SW837 and SW480, two cell lines with a high basal TCF4-activity, whereas no effect was observed in HT-29 a cell line with low activity. Inhibition of β-catenin similarly caused a pronounced sensitization of CRC cells to clinically relevant doses of X-rays. Finally, exogenous stimulation of canonical Wnt signaling with Wnt3a resulted in a significantly decreased sensitivity of RPE cells to radiotherapy, i.e. induced radioresistance.

Conclusion: We have uncovered a novel role of Wnt/β-catenin signaling in mediating resistance to chemoradiotherapy. Moreover, these data suggest that targeting key components of this pathway may represent a potential therapeutic strategy to increase the proportion of patients that respond to chemoradiotherapy, with considerable clinical implications.

Citation Format: Georg Emons, Melanie Spitzner, Sebastian Reineke, Janneke Möller, Emil Kendziorra, Tim Beissbarth, Margret Rave-Fraenk, Jochen Gaedcke, Thomas Ried, Michael Ghadimi, Marian Grade. Wnt/ß-catenin signaling mediates resistance of colorectal cancer cells to chemoradiotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3946. doi:10.1158/1538-7445.AM2014-3946

Abstract 855: Targeting STAT3 in vitro and in vivo reveals a novel therapeutic strategy to sensitize colorectal cancer cells to chemoradiotherapy

Introductory sentence:

Increased activity of signal transducer and activator of transcription 3 (STAT3) is common in human malignancies, including colorectal cancers. Recently, we reported that STAT3 expression correlated with resistance to 5-fluorouracil (5-FU) based chemoradiotherapy. This is of considerable clinical relevance, because a large proportion of rectal cancers are resistant to preoperative multimodal treatment. We therefore examined whether STAT3 contributes to resistance to chemoradiotherapy.

Experimental procedures:

STAT3 mRNA and protein expression levels were determined in 12 colorectal cancers cell lines. STAT3 was inhibited using two different siRNAs and a small-molecular inhibitor (STATTIC) in the cell lines SW480 and SW837. Successful RNAi-mediated silencing of STAT3 or inhibition of phosphoSTAT3(Tyr705) was detected by Western blot and reduction of transcription factor activity was measured by a luciferase reporter assay. Additionally, we established doxycycline-inducible stable shRNA single cell populations and a non-silencing shRNA (shNEG) in SW480. To test the influence of STAT3 knock down or inhibition, clonogenic survival assays were performed. Therefore, RNAi or inhibitor treated cells were exposed to chemoradiotherapy using 3µM 5-FU and X-ray-irradiation at 1, 2, 4, 6, and 8 Gy. Finally, we tested the effect of a chemoradiotherapy combined with STATTIC treatment in a SW837 xenograft model in NMRI nude mice. To verify the sensitizing effect of STATTIC, tumor growth was recorded and growth delay assays were performed.

Data:

STAT3 was overexpressed in resistant cells at mRNA and protein level. siRNA transfected SW480, SW837, and SW480shRNA single cell clones showed a significant reduction of STAT3 protein and transcription factor activity after 96 hours. STATTIC inhibition led to a decreased phosphorylation of STAT3 after 1 hour. The silencing/inhibition resulted in a significantly increased chemoradiosensitivity with dose-reduction factors of 1.3 to 2.5 at a surviving fraction of 0.37. In vivo, additional STAT3 inhibition during chemoradiotherapy led to a profound chemoradiosensitization effect and a significant tumor growth delay in STATTIC treated mice. Survival of these mice was also enhanced, if compared to the control group.

Conclusions:

STAT3 is highly overexpressed in resistant colorectal cancer cells, and silencing or inhibition of STAT3 leads to a significantly increased chemoradiosensitivity in vitro and in vivo. This highlights the potential relevance of STAT3 for mediating treatment resistance and provides a first proof of concept that STAT3 represents a novel molecular target in rectal cancer to sensitize a priori resistant colorectal tumor cells to chemoradiotherapy.

Citation Format: Melanie Spitzner, Birte Roesler, Christian Bielfeld, Carolin Herzberg, Georg Emons, Jochen Gaedcke, Margret Rave-Fränk, Tim Beißbarth, Thomas Ried, B. Michael Ghadimi, Marian Grade. Targeting STAT3 in vitro and in vivo reveals a novel therapeutic strategy to sensitize colorectal cancer cells to chemoradiotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 855. doi:10.1158/1538-7445.AM2014-855

STAT3: A Novel Molecular Mediator of Resistance to Chemoradiotherapy

Chemoradiotherapy (CRT) represents a standard treatment for many human cancers, frequently combined with radical surgical resection. However, a considerable percentage of primary cancers are at least partially resistant to CRT, which represents a substantial clinical problem, because it exposes cancer patients to the potential side effects of both irradiation and chemotherapy. It is therefore exceedingly important to determine the molecular characteristics underlying CRT-resistance and to identify novel molecular targets that can be manipulated to re-sensitize resistant tumors to CRT. In this review, we highlight much of the recent evidence suggesting that the signal transducer and activator of transcription 3 (STAT3) plays a prominent role in mediating CRT-resistance, and we outline why inhibition of STAT3 holds great promise for future multimodal treatment concepts in oncology.

UDP glucuronosyltransferase 1A expression levels determine the response of colorectal cancer cells to the heat shock protein 90 inhibitor ganetespib

HSP90 inhibition represents a promising route to cancer therapy, taking advantage of cancer cell-inherent proteotoxic stress. The HSP90-inhibitor ganetespib showed benefit in advanced clinical trials. This raises the need to identify the molecular determinants of treatment response. We tested the efficacy of ganetespib on a series of colorectal cancer (CRC)-derived cell lines and correlated their sensitivities with comprehensive gene expression analysis. Notably, the drug concentration required for 50% growth inhibition (IC₅₀) varied up to 70-fold (from 36 to 2500 nM) between different cell lines. Correlating cell line-specific IC₅₀s with the corresponding gene expression patterns revealed a strong association between ganetespib resistance (IC₅₀>500 nM) and high expression of the UDP glucuronosyltransferase 1A (UGT1A) gene cluster. Moreover, CRC tumor samples showed a comparable distribution of UGT1A expression levels. The members of the UGT1A gene family are known as drug-conjugating liver enzymes involved in drug excretion, but their function in tumor cells is hardly understood. Chemically unrelated HSP90 inhibitors, for example, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG), did not show correlation of drug sensitivities with UGT1A levels, whereas the ganetespib-related compound NVP-AUY922 did. When the most ganetespib-resistant cell line, HT29, was treated with ganetespib, the levels of HSP90 clients were unaffected. However, HT29 cells became sensitized to the drug, and HSP90 client proteins were destabilized by ganetespib upon siRNA-mediated UGT1A knockdown. Conversely, the most ganetespib-sensitive cell lines HCT116 and SW480 became more tolerant toward ganetespib upon UGT1A overexpression. Mechanistically, ganetespib was rapidly glucuronidated and excreted in resistant but not in sensitive CRC lines. We conclude that CRC cell-expressed UGT1A inactivates ganetespib and other resorcinolic Hsp90 inhibitors by glucuronidation, which renders the drugs unable to inhibit Hsp90 and thereby abrogates their biological activity. UGT1A levels in tumor tissues may be a suitable predictive biomarker to stratify CRC patients for ganetespib treatment.

STAT3 inhibition sensitizes colorectal cancer to chemoradiotherapy in vitro and in vivo

Increased activity of signal transducer and activator of transcription 3 (STAT3) is common in human malignancies, including colorectal cancers (CRCs). We have recently reported that STAT3 gene expression correlates with resistance of CRC cell lines to 5-fluorouracil (5-FU)-based chemoradiotherapy (CT/RT). This is of considerable clinical importance, because a large proportion of rectal cancers are resistant to preoperative multimodal treatment. To test whether STAT3 contributes to CT/RT-resistance, we first confirmed that STAT3 protein expression correlated positively with increasing resistance. While STAT3 was not constitutively active, stimulation with interleukin-6 (IL-6) resulted in remarkably higher expression levels of phosphorylated STAT3 in CT/RT-resistant cell lines. A similar result was observed when we determined IL-6-induced expression levels of phosphorylated STAT3 following irradiation. Next, STAT3 was inhibited in SW480 and SW837 using siRNA, shRNA and the small-molecule inhibitor STATTIC. Successful silencing and inhibition of phosphorylation was confirmed using Western blot analysis and a luciferase reporter assay. RNAi-mediated silencing as well as STATTIC treatment resulted in significantly decreased clonogenic survival following exposure to 3 µM of 5-FU and irradiation in a dose-dependent manner, with dose-modifying factors of 1.3-2.5 at a surviving fraction of 0.37. Finally, STAT3 inhibition led to a profound CT/RT-sensitization in a subcutaneous xenograft model, with a significantly delayed tumor regrowth in STATTIC-treated mice compared with control animals. These results highlight a potential role of STAT3 in mediating treatment resistance and provide first proof of concept that STAT3 represents a promising novel molecular target for sensitizing resistant rectal cancers to CT/RT.

Identification of a microRNA expression signature for chemoradiosensitivity of colorectal cancer cells, involving miRNAs-320a, -224, -132 and let7g

BACKGROUND AND PURPOSE

Preoperative chemoradiotherapy (CRT) represents the standard treatment for locally advanced rectal cancer. Tumor response and progression vary considerably. MicroRNAs represent master regulators of gene expression, and may therefore contribute to this diversity.

MATERIAL AND METHODS

Genome-wide microRNA (miRNA) profiling was performed for 12 colorectal cancer (CRC) cell lines and an individual in vitro signature of chemoradiosensitivity was established. Functional relevance of selected miRNAs was established by transfecting miRNA-mimics into SW480 and SW837 cells. The prognostic value of selected miRNAs was assessed in 128 pretherapeutic patient biopsies.

RESULTS

Thirty-six miRNAs were identified to significantly correlate with sensitivity to CRT (Q < 0.05) including miR-320a and other miRNAs involved in the MAPK-, TGF- and Wnt-pathway. Transfection of selected miRNAs (let-7g, miR-132, miR-224, miR-320a) each induced a shift of sensitivity. High expression of let-7 g was associated with a good prognosis in rectal cancer patients (P = 0.03).

CONCLUSIONS

This is the first report of a miRNA expression signature for in vitro chemoradiosensitivity of CRC cell lines. Many of the identified miRNAs have not been linked to the response to CRT and may represent potential molecular targets to sensitize resistant cancers. If further validated, let7g expression may serve as predictive biomarker.

[General principles of tumour biology in visceral surgery]

Within the last decade, there has been a tremendous progress in understanding the molecular basis of cancer. In particular, the development and the characteristic features of cancer cells are being increasingly understood. The understanding of these molecular characteristics is mandatory for the development of novel, targeted therapeutic strategies and their integration into clinical practice. In addition, tumour genetics play a critically important role for hereditary cancer syndromes, with respect to both diagnostics and clinical decision-making. The aim of this review is to highlight general principles of tumour genetics from a visceral surgeon's point of view, although a comprehensive summary of all aspects would be beyond the scope of this article due to the complexity of the topic.

Abstract 75: CpG methylation signature to predict outcome in preoperatively treated rectal cancer

Introduction: Introducing a preoperative therapy in locally advanced rectal cancer significantly decreased the local recurrence rate whereas outcome was not improved. To identify patient subgroups that could benefit from an adjusted therapy a prediction prior to the preoperative therapy is necessary.

Material and methods: Whole genome promoter methylation analyses were applied to a pilot group of patients (n=11) to identify targets that separate a good and a bad prognosis group based on their methylation level. Using a mass spectrometry based approach (MassArray) candidate CpG probes were assessed in set of 63 patients (training set). Relevant probes were then validated independently in an additional patient set (n=93). Data were then compared to the previously identified biomarkers (CpG island methylatior phenotype (CIPM)) and clinical data.

Results: Relevant DNA regions from whole genome screen were filtered and the number was reduced down to 20 DNA regions located within 17 different genes (244 different CpGs). In the training set thirteen regions could be confirmed and a clear separation into a good and a bad prognosis group was possible (p=0.0394). Validation in an independent cohort revealed a highly significant result (p=0.000341). Comparing the results the methylation panel outperformed CIMP or clinical data.

Conclusion: Using the retrieved methylation panel of 13 different DNA regions allows a highly significant assignment to a good and a bad prognosis group. These data can now be used to identify patients that are well treated by standard therapy and others that benefit from alternative treatment modalities.

Citation Format: Jochen Gaedcke, Rainer Claus, Andreas Leha, Marian Grade, Tim Beißbart, Michael Ghadimi, Dieter Weichenhahn, Christoph Plass. CpG methylation signature to predict outcome in preoperatively treated rectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 75. doi:10.1158/1538-7445.AM2013-75

Abstract 1942: Identification of a microRNA expression signature for radiochemosensitivity of colorectal cancer cells, involving miRNAs-320a, -224, -132 and let7g

Background: Preoperative 5-fluorouracil-based chemoradiotherapy is the standard treatment for locally advanced rectal carcinomas. However, the individual tumor response is very heterogeneous, ranging from complete resistance to regression. Therefore, ascertaining the role of microRNAs (miRNAs) in therapy response as well as identification certain miRNA as predictive markers for response remains very crucial.

Materials/Methods: Using an in-vitro model of 12 colorectal cancer cell lines, we compare the pretherapeutic miRNA expression profiles of these cell lines with the previously assessed radiochemoresistance of each cell lines, respectively. Differences in treatment sensitivity of the cell lines and miRNAs expression were then correlated. Colony formation assays in two independent cell lines were used for the functional validation in-vitro. To asses the clinical applicability miRNA expressions of 64 pretherapeutic biopsies from patients with locally advanced cancer treated with 5-FU based RCT were analyzed.

Results: We identified 36 miRNAs whose expression levels correlated significantly with the heterogeneous sensitivity of the cell lines to chemoradiotherapy (p &lt; 0.05). Microarray measurements were independently validated using semi-quantitative real-time PCR. miR-320, miR-132, miR-429, miR-224 and let-7g were then functionally validated in-vitro by transfection of corresponding miRNA mimics. Analysis of miRNA expression in rectal cancer patients biopsies showed high correlation of miR-224 expression with poor prognosis (p=0.043).

Conclusion: We identified 36 miRNAs that associated with response to chemoradiotherapy. Functional validations of miR-320, miR-132, miR-429, miR-224 and let-7g have been undertaken in-vitro underlining the regulatory effects of the specific miRNAs. Further miR-224 found out to be significantly correlated to Disease Free Survival (DFS). An independent prospective validation in a clinical trial will be performed.

Citation Format: Junius Salendo, Melanie Spitzner, Frank Kramer, Peter Jo, Tim Beissbarth, Hendrik A. Wolff, Heinz Becker, Mathias Dobbelstein, Michael Ghadimi, Marian Grade, Jochen Gaedcke. Identification of a microRNA expression signature for radiochemosensitivity of colorectal cancer cells, involving miRNAs-320a, -224, -132 and let7g. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1942. doi:10.1158/1538-7445.AM2013-1942

Abstract 1588: Canonical Wnt signaling mediates resistance of colorectal cancer cells to radiation therapy

Background: The clinical response of locally advanced rectal cancers to preoperative chemoradiotherapy is very heterogeneous. We previously identified TCF4, the key downstream effector of the Wnt/β-catenin signaling pathway, as over-expressed in tumors that were resistant to chemoradiotherapy. The aim of this study was to explore the potential functional relevance of Wnt/ß-catenin signaling for mediating treatment resistance.

Methods: Using RNA interference, TCF4 and β-catenin were inhibited in the colorectal cancer cell lines SW837 and SW480. Subsequently, these cell lines were irradiated with varying doses of X-rays. In addition, normal retinal epithelial cells (RPE) were stimulated with Wnt-3a for 28 hours, and also irradiated. Wnt/β-catenin activity was assessed using the TOPFLASH/FOPFLASH reporter assay, and induction of Axin2 was confirmed by Western blotting.

Results: Protein levels of both TCF4 and β-catenin were considerably reduced following RNAi, accompanied by a decreased TOP/FOP reporter activity. Importantly, silencing of both proteins led to a pronounced radiosensitization in SW837 and SW480 cells. Exogenous stimulation of canonical Wnt signaling in RPE cells using Wnt-3a resulted in an increased Axin2 expression and an increased TOP/FOP reporter activity. Importantly, however, this activation of canonical Wnt signaling was associated with significant increase in resistance to radiation therapy.

Conclusion: TCF4 was found to be over-expressed in resistant rectal carcinomas, and its RNAi-mediated silencing caused a significant radiosensitization. To determine whether this effect was dependent on canonical Wnt signaling, we inhibited ß-catenin, another key factor of this pathway and binding partner of TCF4, and observed a similar sensitization to radiation therapy. Follow-up experiments show that external stimulation of canonical Wnt signaling confers radiation resistance in normal cells. These data suggest that targeting canonical Wnt signaling may represent a potential therapeutic strategy for sensitizing tumor cells to radiation. In vivo studies are ongoing to validate these results.

Citation Format: Georg Emons, Janneke Möller, Melanie Spitzner, Emil Kendziorra, Jochen Gaedcke, Margret Rave-Fränk, Tobias Pukrop, Michael Ghadimi, Thomas Ried, Marian Grade. Canonical Wnt signaling mediates resistance of colorectal cancer cells to radiation therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1588. doi:10.1158/1538-7445.AM2013-1588

Abstract 68: Targeting STAT3 in vitro and in vivo reveals a novel therapeutic strategy to sensitize colorectal cancer cells to chemoradiotherapy

Introductory sentence:

Increased activity of signal transducer and activator of transcription 3 (STAT3) is common in human malignancies, including colorectal cancers. Recently, we reported that STAT3 expression correlated with resistance to 5-fluorouracil (5-FU) based chemoradiotherapy. This is of considerable clinical relevance, because a large proportion of rectal cancers are resistant to preoperative multimodal treatment. We therefore examined whether STAT3 contributes to resistance to chemoradiotherapy.

Experimental procedures:

STAT3 mRNA and protein expression levels were determined in 12 colorectal cancers cell lines. STAT3 was inhibited using two different siRNAs and a small-molecular inhibitor (STATTIC) in the cell lines SW480 and SW837. Successful RNAi-mediated silencing of STAT3 or inhibition of phosphoSTAT3(Tyr705) was detected by Western blot and reduction of transcription factor activity was measured by a luciferase reporter assay. Additionally, we established doxycycline-inducible stable shRNA single cell populations and a non-silencing shRNA (shNEG) in SW480. To test the influence of STAT3 knock down or inhibition, clonogenic survival assays were performed. Therefore, RNAi or inhibitor treated cells were exposed to chemoradiotherapy using 3μM 5-FU and X-ray-irradiation at 1, 2, 4, 6, and 8 Gy. Finally, we tested the effect of a chemoradiotherapy combined with STATTIC treatment in a SW837 xenograft model in NMRI nude mice. To verify the sensitizing effect of STATTIC, tumor growth was recorded and growth delay assays were performed.

Data:

STAT3 was overexpressed in resistant cells at mRNA and protein level. siRNA transfected SW480, SW837, and SW480shRNA single cell clones showed a significant reduction of STAT3 protein and transcription factor activity after 96 hours. STATTIC inhibition led to a decreased phosphorylation of STAT3 after 1 hour. The silencing/inhibition resulted in a significantly increased chemoradiosensitivity with dose-reduction factors of 1.3 to 2.5 at a surviving fraction of 0.37. In vivo, additional STAT3 inhibition during chemoradiotherapy led to a profound chemoradiosensitization effect and a significant tumor growth delay in STATTIC treated mice. Survival of these mice was also enhanced, if compared to the control group.

Conclusions:

STAT3 is highly overexpressed in resistant colorectal cancer cells, and silencing or inhibition of STAT3 leads to a significantly increased chemoradiosensitivity in vitro and in vivo. This highlights the potential relevance of STAT3 for mediating treatment resistance and provides a first proof of concept that STAT3 represents a novel molecular target in rectal cancer to sensitize a priori resistant colorectal tumor cells to chemoradiotherapy.

Citation Format: Melanie Spitzner, Birte Roesler, Christian Bielfeld, Carolin Herzberg, Georg Emons, Jochen Gaedcke, Margret Rave-Fränk, Tim Beißbarth, Thomas Ried, B. Michael Ghadimi, Marian Grade. Targeting STAT3 in vitro and in vivo reveals a novel therapeutic strategy to sensitize colorectal cancer cells to chemoradiotherapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 68. doi:10.1158/1538-7445.AM2013-68

[Value of one-stage surgical treatment of diffuse peritonitis (relaparotomy on demand): a single-center analysis]

BACKGROUND

Despite modern surgical and intensive-care concepts, diffuse peritonitis remains a major source of high morbidity and mortality. The aim of this study was to critically evaluate the value of relaparotomy on demand (ROD) for patients with diffuse peritonitis.

PATIENTS AND RESULTS

In a retrospective analysis, the clinical course of 231 patients with diffuse peritonitis was analysed. The mean Mannheim Peritonitis Index (MPI) was 25.3. Overall lethality in this cohort was 14.3 %. In 214 patients, source control was successful during the index operation, and these patients were treated according to an on-demand strategy. For 178 of these patients, there was no demand for a relaparotomy, whereas 36 of these patients required further surgical interventions. Lethality for these subgroups was 9 % (no relaparotomy) and 27 % (relaparotomy), respectively.

CONCLUSIONS

This retrospective analysis confirms that an on-demand strategy is reasonable and feasible after successful source control and lavage. However, it still remains of clinical importance to identify parameters that may assist in selecting those patients who require a relaparotomy.

Increasing toxicity during neoadjuvant radiochemotherapy as positive prognostic factor for patients with esophageal carcinoma

The aim of this study was to correlate acute organ toxicity during preoperative radiochemotherapy with overall survival and tumor regression for patients with primarily operable esophageal carcinoma. From 1995 to 2002, 60 patients with primarily operable esophageal carcinoma were treated in a preoperative setting at our department. Thirty-three percent of the patients had International Union against Cancer (UICC)-stage II tumors, 62% had UICC-stage III tumors, and 5% had UICC-stage IVA tumors. All patients received irradiation (40 Gy at 2 Gy/fraction). Chemotherapy for all patients with adenocarcinoma and, from 2001, also for patients with squamous cell carcinoma consisted of two cycles, 5-fluorouracil and cisplatinum; between 1995 and 2001, patients with squamous cell carcinoma received three courses of chemotherapy (folinic acid, etoposide, 5-fluorouracil, and cisplatinum every 3 weeks) before and further cisplatinum and etoposide during radiotherapy. We found a significant correlation between acute organ toxicity and histopathological tumor regression, as well as overall survival. The probability to achieve tumor regression grade 1 after radiochemotherapy was nearly four times higher for patients with worsening of odynophagia than for those without an increase (odds ratio: 3.97). Patients with worsening of odynophagia had a 5-year overall-survival rate of 66% compared with 39% in patients without (P = 0.048). Our data indicate that normal tissue and tumor tissue may behave similar with respect to treatment response, as acute organ toxicity showed to be an independent prognostic marker in our patient population. The hypothesis should be further analyzed on biomolecular and clinical level in future clinical trials.

STAT3 as a potential molecular target to sensitize colorectal cancer cells to chemoradiotherapy

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Background: Resistance to preoperative chemoradiotherapy represents a major clinical problem in the treatment of patients with locally advanced rectal cancer. Therefore, the identification of molecular biomarkers that differentiate responsive and resistant tumors is exceedingly important, because this may lead to the identification of novel molecular targets whose modification could be harnessed to sensitize a priori resistant tumors to multimodal treatment. Methods: We recently established an in vitro model for 5-FU based chemoradiotherapy, and correlated differences in treatment sensitivity of 12 colorectal cancer cell lines with pretherapeutic gene expression profiles. One gene the expression of which correlated positively with treatment resistance was the signal transducer and activator of transcription 3, STAT3. To test the functional relevance of this observation, we first determined STAT3 mRNA and protein expression levels in all cell lines. Next, we established doxycycline-inducible stable shRNA single-cell clone (SCC) populations. Successful silencing of STAT3 was detected by Western blot analysis. The induced SCCs were treated with 3 µM 5-FU, and subsequently exposed to 0, 1, 2, 4, 6, and 8 Gy of X-rays. In addition, STAT3 was inhibited using two different siRNAs, and a small-molecular inhibitor (STATTIC). Results: STAT3 was significantly overexpressed in resistant cells. In SW480 and SW837 cells, both shRNA- and siRNA-mediated silencing as well as STATTIC-induced inhibition of STAT3-phosphorylation resulted in a significantly increased chemoradiosensitivity, with dose-reduction factors of 1.8 to 2. Conclusions: These results highlight the potential relevance of STAT3 as a novel molecular target to sensitize a priori resistant tumor cells to chemoradiotherapy.

Genetic amplification of the NOTCH modulator LNX2 upregulates the WNT/β-catenin pathway in colorectal cancer

Chromosomal copy number alterations (aneuploidy) define the genomic landscape of most cancer cells, but identification of the oncogenic drivers behind these imbalances remains an unfinished task. In this study, we conducted a systematic analysis of colorectal carcinomas that integrated genomic copy number changes and gene expression profiles. This analysis revealed 44 highly overexpressed genes mapping to localized amplicons on chromosome 13, gains of which occur often in colorectal cancers (CRC). RNA interference (RNAi)-mediated silencing identified eight candidates whose loss-of-function reduced cell viability 20% or more in CRC cell lines. The functional space of the genes NUPL1, LNX2, POLR1D, POMP, SLC7A1, DIS3, KLF5, and GPR180 was established by global expression profiling after RNAi exposure. One candidate, LNX2, not previously known as an oncogene, was involved in regulating NOTCH signaling. Silencing LNX2 reduced NOTCH levels but also downregulated the transcription factor TCF7L2 and markedly reduced WNT signaling. LNX2 overexpression and chromosome 13 amplification therefore constitutively activates the WNT pathway, offering evidence of an aberrant NOTCH-WNT axis in CRC.