Hemant M. Kocher

Development of a dedicated risk-adjustment scoring system for colorectal surgery (colorectal POSSUM).

The aim of the study was to develop a dedicated colorectal Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (CR‐POSSUM) equation for predicting operative mortality, and to compare its performance with the Portsmouth (P)‐POSSUM model.

Analysis of mortality rates for pancreatic cancer across the world

INTRODUCTION Pancreas cancer is the fourth commonest cause of cancer-related mortality across the world, with incidence equalling mortality. A recent study has suggested that both the incidence and the mortality of pancreatic cancer are falling in the UK. We investigated whether this trend was being seen all over the world. METHODS Age-standardized mortality (world) rates [ASR(W)] for pancreatic cancer were extracted separately for males and females from a database maintained by the International Agency for Research on Cancer for 51 countries across the world (Europe, 33 countries; Americas, 8 countries; and Asia, 10 countries) for the period 1992-2002; log-linear regression analysis was performed to analyse trends in the past decade. RESULTS In the period 1992-2002, the ASR(W) remained static across most countries for both sexes. The highest mortality rates (for both sexes) were seen in Central Europe [range: men (8-12), women (4.5-7)] with trends towards increasing mortality in Romania (p<0.001), along with Albania, Spain and Croatia (p<0.01). Korea in the Far East, too, demonstrated increasing mortality trends for both sexes (men p<0.001, women p<0.01). Increasing mortality trends were also observed among women in France (p<0.001). In Canada, there was a decline in mortality [men (7.5-6.4), women (5.9-5); p<0.01], while for men there was a downward trend in Ireland, the UK, Switzerland, Austria, and Poland [p<0.05]. CONCLUSION The changes perhaps reflect standardization and consolidation of diagnostic tests for pancreatic cancer in the Western world and further in-depth analysis would be required.

Locating the stem cell niche and tracing hepatocyte lineages in human liver.

We have used immunohistochemical and histochemical techniques to identify patches of hepatocytes deficient in the enzyme cytochrome c oxidase, a component of the electron transport chain and encoded by mitochondrial DNA (mtDNA). These patches invariably abutted the portal tracts and expanded laterally as they spread toward the hepatic veins. Here we investigate, using mtDNA mutations as a marker of clonal expansion, the clonality of these patches. Negative hepatocytes were laser‐capture microdissected and mutations identified by polymerase chain reaction sequencing of the entire mtDNA genome. Patches of cytochrome c oxidase–deficient hepatocytes were clonal, suggesting an origin from a long‐lived cell, presumably a stem cell. Immunohistochemical analysis of function and proliferation suggested that these mutations in cytochrome c oxidase‐deficient hepatocytes were nonpathogenic. Conclusion: these data show, for the first time, that clonal proliferative units exist in the human liver, an origin from a periportal niche is most likely, and that the trajectory of the units is compatible with a migration of cells from the periportal regions to the hepatic veins. (HEPATOLOGY 2009.)

Evaluation of POSSUM and P-POSSUM scoring systems in patients undergoing colorectal surgery.

The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and Portsmouth POSSUM (P‐POSSUM) equations were derived from a heterogeneous general surgical population and have been used successfully as audit tools to provide risk‐adjusted operative mortality rates. Their applicability to high‐risk emergency colorectal operations has not been established.

Clinical presentation and operative repair of hernia of Morgagni

A 77 year old woman who presented with an incarcerated hernia of Morgagni was successfully treated without complications. A Medline search (1996 to date) along with cross referencing was done to quantify the number of acute presentations in adults compared to children. Different investigating modalities—for example, lateral chest and abdominal radiography, contrast studies or, in difficult cases, computed tomography or magnetic resonance imaging—can be used to diagnose hernia of Morgagni. The favoured method of repair—laparotomy or laparoscopy—is also discussed. A total of 47 case reports on children and 93 case reports on adults were found. Fourteen percent of children (seven out of 47) presented acutely compared with 12% of adults (12 out of 93). Repair at laparotomy was the method of choice but if uncertain, laparoscopy would be a useful diagnostic tool before attempted repair. Laparoscopic repair was favoured in adults especially in non-acute cases.

Key Role of Phosphoinositide 3-Kinase Class IB in Pancreatic Cancer

Purpose: Phosphoinositide 3-kinase (PI3K) signaling is well established as important in cancer. To date most studies have been focused on the PI3K/p110α isoform, which has been found to be mutated in several different cancers. The aim of our study was to determine which specific PI3K isoforms are involved in pancreatic ductal adenocarcinoma (PDAC) and investigate the effects of these isoforms on proliferation, survival, and induction of Akt activation in pancreatic cancer cells. Experimental Design: The expression of all PI3K isoforms and downstream targets was analyzed by immunohistochemistry in human pancreatic cancer tissue and normal counterparts. Isoform selective inhibitors and short interfering RNA (siRNA) were employed to investigate the effects of the different PI3Ks on proliferation, survival, and intracellular signaling in PDAC cell lines. Results: Immunohistochemical screening revealed high specific expression of the PI3K/p110γ isoform. Scoring indicated that 72% of the PDAC tissue stained positive for PI3K/p110γ, whereas no stain was detected in normal pancreatic ducts. Proliferation analyses after selective inhibition and siRNA downregulation of PI3K/p110γ showed that PI3K/p110γ, but not other PI3K isoforms, was required for cell proliferation. Overexpression of PI3K/p110γ indeed increased cell numbers and mediated activation of Akt in PDAC cell lines. Moreover, PI3K/p110γ was required for Akt activation via lysophosphatidic acid receptors. Conclusions: These data represent the first identification of a tumor-specific accumulation of the PI3K isoform p110γ in human cancer. Further, our results signify a critical role for PI3K/p110γ in pancreatic cancer, and we hypothesize that PI3K/p110γ overexpression is a key event in the disease progression. Clin Cancer Res; 16(20); 4928–37. ©2010 AACR.

Nuclear translocation of FGFR1 and FGF2 in pancreatic stellate cells facilitates pancreatic cancer cell invasion.

Pancreatic cancer is characterised by desmoplasia, driven by activated pancreatic stellate cells (PSCs). Over‐expression of FGFs and their receptors is a feature of pancreatic cancer and correlates with poor prognosis, but whether their expression impacts on PSCs is unclear. At the invasive front of human pancreatic cancer, FGF2 and FGFR1 localise to the nucleus in activated PSCs but not cancer cells. In vitro, inhibiting FGFR1 and FGF2 in PSCs, using RNAi or chemical inhibition, resulted in significantly reduced cell proliferation, which was not seen in cancer cells. In physiomimetic organotypic co‐cultures, FGFR inhibition prevented PSC as well as cancer cell invasion. FGFR inhibition resulted in cytoplasmic localisation of FGFR1 and FGF2, in contrast to vehicle‐treated conditions where PSCs with nuclear FGFR1 and FGF2 led cancer cells to invade the underlying extra‐cellular matrix. Strikingly, abrogation of nuclear FGFR1 and FGF2 in PSCs abolished cancer cell invasion. These findings suggest a novel therapeutic approach, where preventing nuclear FGF/FGFR mediated proliferation and invasion in PSCs leads to disruption of the tumour microenvironment, preventing pancreatic cancer cell invasion.

A methodological approach to tracing cell lineage in human epithelial tissues.

Methods for lineage tracing of stem cell progeny in human tissues are currently not available. We describe a technique for detecting the expansion of a single cells progeny that contain clonal mitochondrial DNA (mtDNA) mutations affecting the expression of mtDNA‐encoded cytochrome c oxidase (COX). Because such mutations take up to 40 years to become phenotypically apparent, we believe these clonal patches originate in stem cells. Dual‐color enzyme histochemistry was used to identify COX‐deficient cells, and mutations were confirmed by microdissection of single cells with polymerase chain reaction sequencing of the entire mtDNA genome. These techniques have been applied to human intestine, liver, pancreas, and skin. Our results suggest that the stem cell niche is located at the base of colonic crypts and above the Paneth cell region in the small intestine, in accord with dynamic cell kinetic studies in animals. In the pancreas, exocrine tissue progenitors appeared to be located in or close to interlobular ducts, and, in the liver, we propose that stem cells are located in the periportal region. In the skin, the origin of a basal cell carcinoma appeared to be from the outer root sheath of the hair follicle. We propose that this is a general method for detecting clonal cell populations from which the location of the niche can be inferred, also affording the generation of cell fate maps, all in human tissues. In addition, the technique allows analysis of the origin of human tumors from specific tissue sites. STEM CELLS 2009;27:1410–1420

Imbalance of desmoplastic stromal cell numbers drives aggressive cancer processes

Epithelial tissues have sparse stroma, in contrast to their corresponding tumours. The effect of cancer cells on stromal cells is well recognized. Increasingly, stromal components, such as endothelial and immune cells, are considered indispensable for cancer progression. The role of desmoplastic stroma, in contrast, is poorly understood. Targeting such cellular components within the tumour is attractive. Recent evidence strongly points towards a dynamic stromal cell participation in cancer progression that impacts patient prognosis. The role of specific desmoplastic stromal cells, such as stellate cells and myofibroblasts in pancreatic, oesophageal and skin cancers, was studied in bio‐engineered, physiomimetic organotypic cultures and by regression analysis. For pancreatic cancer, the maximal effect on increasing cancer cell proliferation and invasion, as well as decreasing cancer cell apoptosis, occurs when stromal (pancreatic stellate cells) cells constitute the majority of the cellular population (maximal effect at a stromal cell proportion of 0.66–0.83), accompanied by change in expression of key molecules such as E‐cadherin and β‐catenin. Gene‐expression microarrays, across three tumour types, indicate that stromal cells consistently and significantly alter global cancer cell functions such as cell cycle, cell–cell signalling, cell movement, cell death and inflammatory response. However, these changes are mediated through cancer type‐specific alteration of expression, with very few common targets across tumour types. As highlighted by these in vitro data, the reciprocal relationship of E‐cadherin and polymeric immunoglobulin receptor (PIGR) expression in cancer cells could be shown, in vivo, to be dependent on the stromal content of human pancreatic cancer. These studies demonstrate that context‐specific cancer–stroma crosstalk requires to be precisely defined for effective therapeutic targeting. These data may be relevant to non‐malignant processes where epithelial cells interact with stromal cells, such as chronic inflammatory and fibrotic conditions. Copyright

The histogenesis of regenerative nodules in human liver cirrhosis

Here, we investigate the clonality and cells of origin of regenerative nodules in human liver cirrhosis using mitochondrial DNA (mtDNA) mutations as markers of clonal expansion. Mutated cells are identified phenotypically by deficiency in the entirely mtDNA encoded cytochrome c oxidase (CCO) enzyme by histochemical and immunohistochemical methods. Nodules were classified as either CCO‐deficient or CCO‐positive, and among 526 nodules from 10 cases, 18% were homogeneously CCO‐deficient, whereas only 3% had a mixed phenotype. From frozen sections, hepatocytes were laser‐capture microdissected from several sites within individual CCO‐deficient nodules. Mutations were identified by polymerase chain reaction sequencing of the entire mtDNA genome. In all cases except for one, the nodules were monoclonal in nature, possessing up to four common mutations in all hepatocytes in a given nodule. Moreover, the identification of identical mutations in hepatic progenitor cells abutting CCO‐deficient nodules proves that nodules can have their origins from such cells. Conclusion: These data support a novel pathway for the monoclonal derivation of human cirrhotic regenerative nodules from hepatic progenitor cells. (HEPATOLOGY 2010;51:1017–1026.)