Dale Vimalachandran

High Nuclear S100A6 (Calcyclin) Is Significantly Associated with Poor Survival in Pancreatic Cancer Patients

Recent studies have reported elevated levels of S100A6 in pancreatic ductal adenocarcinoma cells. Here, we describe a detailed analysis of S100A6 expression in benign (n = 32), malignant (n = 60), and premalignant pancreatic ductal cells [96 pancreatic intraepithelial neoplasias (PanIN) from 46 patients]. S100A6 staining was more intense in malignant cells than in benign cells (P = 0.0001). In malignant cells, staining was higher in the nucleus than in the cytoplasm (P = 0.003). Univariate analysis revealed a significant decrease in survival time for patients with high levels of nuclear (P = 0.01) but not cytoplasmic (P = 0.20) S100A6. No evidence was found for an association between nuclear S100A6 expression and other variables, including gender, age at surgery, tumor size or grade, nodal metastases, resection margin, vascular invasion, perineural invasion, p53 or Smad4 levels (both linked to survival in previous studies), or the p65 subunit of nuclear factor-kappaB (a potential regulator of S100A6). Although nodal metastases and resection margin involvement were also associated with poor survival (P = 0.06 in both cases), multivariate analysis suggests that nuclear S100A6 is a significant independent indicator of survival (P = 0.003). Whereas PanIN 1a lesions showed a general absence of S100A6 staining, there was a progressive increase in the proportion of positively stained PanINs with increasing PanIN grade. In particular, we observed an increase in the frequency and intensity of nuclear staining. Our results suggest that up-regulation of S100A6 is an early event in pancreatic cancer development and that elevated levels of nuclear S100A6 may affect clinical outcome.

Pancreatic cancer cells overexpress gelsolin family-capping proteins, which contribute to their cell motility

Background: Previously, proteomic methods were applied to characterise differentially expressed proteins in microdissected pancreatic ductal adenocarcinoma cells. Aims: To report that CapG and a related protein, gelsolin, which have established roles in cell motility, are overexpressed in metastatic pancreatic cancer; and to describe their pattern of expression in pancreatic cancer tissue and their effect on cell motility in pancreatic cancer cell lines. Methods: CapG was identified by mass spectrometry and immunoblotting. CapG and gelsolin expression was assessed by immunohistochemical analysis on a pancreatic cancer tissue microarray and correlated with clinical and pathological parameters. CapG and gelsolin levels were reduced using RNA interface in Suit-2, Panc-1 and MiaPaCa-2 cells. Cell motility was assessed using modified Boyden chamber or wound-healing assays. Results: Multiple isoforms of CapG were detected in pancreatic cancer tissue and cell lines. Immunohistochemical analysis of benign (n = 44 patients) and malignant (n = 69) pancreatic ductal cells showed significantly higher CapG staining intensity in nuclear (p<0.001) and cytoplasmic (p<0.001) compartments of malignant cells. Similarly, gelsolin immunostaining of benign (n = 24 patients) and malignant (n = 68 patients) pancreatic ductal cells showed higher expression in both compartments (both p<0.001). High nuclear CapG was associated with increased tumour size (p = 0.001). High nuclear gelsolin was associated with reduced survival (p = 0.01). Reduction of CapG or gelsolin expression in cell lines by RNAi was accompanied by significantly impaired motility. Conclusions: Up regulation of these actin-capping proteins in pancreatic cancer and their ability to modulate cell motility in vitro suggest their potentially important role in pancreatic cancer cell motility and consequently dissemination.

Genetics and prevention of pancreatic cancer.

BACKGROUND Pancreatic cancer is an aggressive disease with a poor prognosis. Hereditary factors have been reported in up to 10% of cases of pancreatic cancer. The clinical characteristics and genetic abnormalities have been identified for a proportion of this high-risk group, and the development of preventive strategies for these individuals is now a primary goal of cancer clinicians. METHODS A review of the current literature regarding the genetics, screening, and prevention of pancreatic cancer and its precursor lesions was undertaken. RESULTS Risk factors for pancreatic cancer include smoking, chronic pancreatitis, and a genetic predisposition. The role of diabetes or a diet high in fat or meat remains unclear. The genetic mutations that accompany pancreatic cancer appear to occur in a temporal sequence, beginning in the earliest of precursor lesions. These mutations are detectable in pancreatic juice and, in conjunction with imaging, form the basis of screening programs for high-risk individuals. Not all precursor lesions will undergo malignant transformation, and testing is currently limited in its ability to determine which lesions will undergo transformation. CONCLUSIONS Avoiding tobacco smoking and minimizing risk factors associated with chronic pancreatitis are recommended to reduce the risk of pancreatic cancer. Individuals with a high-risk genetic background require counseling, genetic testing if appropriate (BRCA2 mutation or p16INK4A inactivity) and secondary screening for pancreatic cancer in specialist centers. Risk stratification will improve as more genetic abnormalities causing pancreatic cancer are defined.

Proteomic technologies and their application to pancreatic cancer

Pancreatic ductal adenocarcinoma is a devastating disease that represents an important health problem. It spreads rapidly at a time when patients have relatively few symptoms and consequently is often only detected at an advanced stage when treatment options are limited. Rapid developments in technology and bioinformatics have recently led to a surge in proteomics-based cancer research. Comparative analysis of protein profiles from nonmalignant and malignant pancreas cells or tissue, or from different stages of pancreatic cancer, potentially offer unique insight into the biology of this tumor type. Furthermore, proteomic approaches may provide novel diagnostic or therapeutic markers for this disease. Although such analyses are still in their infancy, they show great potential in the ongoing battle against this dismal disease.

From mice to men: Murine models of colorectal cancer for use in translational research.

Colorectal cancer (CRC) is the third most common carcinoma worldwide and despite advances in treatment, survival for patients with metastatic disease remains poor. With nearly 50% of patients developing metastases, in vivo investigation is essential to improve outcomes for these patients and numerous murine models of CRC have been developed to allow the study of chemoprevention and chemotherapy, in addition to improving our understanding of the pathogenesis of CRC. Selecting the most appropriate murine model for a specific application will maximize the conversion of potential therapies from the laboratory to clinical practice and requires an understanding of the various models available. This review will provide an overview of the murine models currently used in CRC research, discussing the limitations and merits of each and their most relevant application. It is aimed at the developing researcher, acting as a guide to prompt further reading in planning a specific study.

Oesophageal perforation caused by screw displacement 16 months following anterior cervical spine fixation

Anterior cervical spine plating is a standard procedure for fixing unstable vertebral fractures. Following surgery, oesophageal perforation has an incidence of 0.25% and this is usually hours following surgery, due to over prominent screws or friction between the oesophagus and the plate. Instrumentation failure of these plates months or years following surgery is very rare but potentially life-threatening. We report a case of microcytic anaemia which was investigated by oesophagogastroduodenoscopy, and subsequently found that a screw from the anterior plate had lifted off and perforated the oesophagus. This is very rare, but emphasises an important lesson. Anyone presenting with gastrointestinal bleeding or infectious signs, with a history of cervical spine plating should be investigated immediately for instrumentation failure as it brings a high mortality.

Outcome of colorectal cancer resection in octogenarians

INTRODUCTION Octogenarians constitute a rapidly growing segment of patients undergoing colorectal cancer resection, but their outcomes remain understudied and under-reported. Our aims were to analyse outcomes of octogenarian patients undergoing curative colorectal resections compared with a similar cohort 2 decades younger. METHODS Data from a prospectively collected database of consecutive patients undergoing colorectal resection between 2004 and 2006 were analysed. Primary endpoints were 30-day mortality and morbidity. The secondary endpoint was long-term survival. RESULTS Eighty-one consecutive patients aged >80 years and 61 patients aged 60 - 70 years undergoing elective and emergency resections were identified. In the octogenarian group, 75.3% of resections were elective compared with 78.0% in the younger cohort (p=0.9), with pelvic procedures accounting for 34.6% and 44.3%, respectively (p=0.34). The elderly had a significantly higher median CR-Possum (performance status) score than the younger cohort (18.0 v. 14.0; p=0.001). Permanent stoma rates were similar (22% for octogenarians v. 27% for younger patients; p=0.8), as was pathological stage (p=0.24). There was 1 death within 30 days after resection in each group. Median survival in the octogenarian cohort was 73 months compared with 74 months in the younger cohort, and 5-year survival rates were 53.1% and 66.0%, respectively (p=0.2, Mantel-Cox). CR-Possum score did not affect overall survival (p=0.711, Mantel-Cox), but a higher score correlated with more postoperative complications in both groups. CONCLUSIONS Octogenarians have poor performance status, but can undergo resection with acceptable mortality and morbidity. Overall survival in the two age groups studied was similar, with poor performance status being associated with higher postoperative complications but no long-term difference in survival.

Proteomic profiling of rectal cancer reveals acid ceramidase is implicated in radiation response

BACKGROUND Neoadjuvant chemoradiotherapy (CRT) is used in locally advanced rectal cancer when tumours threaten the circumferential resection margin, with varying response to treatment. This experimental study aimed to identify significantly differentially expressed proteins between patients responding and not responding to CRT, and to validate any proteins of interest. METHODS Mass spectrometry (with isobaric tagging for relative quantification) analysis of rectal cancers pre- and post-CRT, and at resection. Validation of proteins of interest was performed by assessing tissue microarray (TMA) immunohistochemistry expression in a further 111 patients with rectal cancer. RESULTS Proteomic data are available via ProteomeXchange with identifier PXD008436. Reduced abundance of contributing peptide ions for acid ceramidase (AC) (log fold change -1.526, p = 1.17E-02) was observed in CRT responders. Differential expression of AC was confirmed upon analysis of the TMAs. Cancer site expression of AC in stromal cells from post-CRT resection specimens was observed to be relatively low in pathological complete response (p = 0.003), and relatively high with no response to CRT (p = 0.017). CONCLUSION AC may be implicated in the response of rectal cancer to CRT. We propose its further assessment as a novel potential biomarker and therapeutic target. SIGNIFICANCE There is a need for biomarkers to guide the use of chemoradiotherapy in rectal cancer, as none are in routine clinical use. We have determined acid ceramidase may have a role in radiation response, based on novel proteomic profiling and validation in a wider dataset using tissue microarrays. The ability to predict or improve response would positively select those patients who will derive benefit, prevent delays in the local and systemic management of disease in non-responders, and reduce morbidity associated with chemoradiotherapy.

Proteomic analysis to identify biomarkers in the primary tumour that predict response to neoadjuvant chemotherapy in liver metastases

BACKGROUND Colorectal cancer is the fourth commonest cancer in the UK, and the second commonest cause of cancer-related death. A knowledge of the biological phenotype of colorectal liver metastases would be invaluable to inform clinical decision making; however, deriving this information from the metastatic lesions is not feasible until after resection. We aimed to use proteomic analysis to identify biomarkers in the primary tumour that predict response to neoadjuvant chemotherapy in liver metastases. METHODS Fresh tissue from both primary colorectal tumour and liver metastases from 17 patients was subjected to proteomic analysis using isobaric tagging for relative quantification. Data were analysed with Protein Pilot (Ab Sciex, Framingham, MA, USA), with stratification of patients into those showing low or high response to chemotherapy permitting the identification of potential predictive biomarkers. These markers were subsequently validated by immunohistochemistry on a tissue microarray of 63 patients. FINDINGS We identified 5768 discrete proteins. Five of them predicted histopathological response to fluorouracil-based chemotherapy regimens, of which the FAD binding protein NQO1 was subsequently validated by immunohistochemistry. When compared with the chemotherapeutic agent alone, knockdown of the corresponding gene with small interfering RNA decreased cell viability when co-incubated with fluorouracil (77·1% vs 46·6%, p=0·037) and irinotecan (41·7% vs 24·4%, p=0·006). Similar results were also seen after inhibition of protein activity by pretreating cells with dicoumarol. INTERPRETATION These results show that proteomic sequencing of matched metastatic colorectal cancer samples is feasible, with high protein coverage. The high degree of similarity between the primary and secondary proteomes suggests that primary tissue is predictive of the metastatic phenotype. NQO1 expression in the primary tumour predicts response to neoadjuvant chemotherapy in the liver metastases, and inhibition of this protein at both genetic and functional levels improves chemosensitivity. FUNDING Cancer Research UK.

Targeting Heat Shock Proteins in Colorectal Cancer

Colorectal cancer (CRC) causes over half a million deaths worldwide and has a particularly poor prognosis when diagnosed at an advanced stage. Heat shock proteins (HSP) have been found to be elevated in CRC patients and HSPB1, HSPA1A and HSPC1 has been shown to have some prognostic value. CRC, in common with all cancers, has important associated oncogene and tumor suppressor gene associations and we show how many of these interact directly with one or more of the HSP. We discuss the current chemotherapeutic options available to the clinician when presented with CRC and how these may be improved with a consideration of the role of HSP in the development of the tumor as well as the response to therapy. Direct manipulation of HSP has the potential to decrease the therapeutic dose of anti-tumor drugs and we propose novel strategies that have the potential to be adapted to the clinic.