Kieran Sheahan

Pathological response following long-course neoadjuvant chemoradiotherapy for locally advanced rectal cancer.

Aims : To standardize the pathological analysis of total mesorectal excision specimens of rectal cancer following neoadjuvant chemoradiotherapy for locally advanced disease (T3/T4), including tumour regression.

Tissue cytokine and chemokine expression in inflammatory bowel disease

Abstract.Objective and design: This study aimed to determine if mucosal expression of the chemokines IL-8, RANTES and MCP-1 and the pro-inflammatory cytokines TNFα and IL-6 are elevated in patients with inflammatory bowel disease.¶Materials and subjects: Intestinal mucosa samples were obtained at the time of surgical resection, n=16 from each of the following groups: normal/control, CD and UC.¶Methods: An homogenate was prepared of each tissue sample and cytokines measured by ELISA.¶Results: IL-8 was significantly increased in both disease groups compared to controls Similarly, RANTES levels were also significantly increased. MCP-1 levels were increased in both disease groups, this increase was statistically significant in the UC group only. TNFα and IL-6 were significantly increased in the CD group only.¶Conclusions: Chemokines, together with key cytokines that promote their release are elevated in mucosal tissues from patients with IBD. It is likely that these chemokines play an important role in the perpetuation of tissue destructive inflammatory processes.

Tumor budding is a strong and reproducible prognostic marker in T3N0 colorectal cancer.

Background Tumor budding along the advancing front of colorectal adenocarcinoma is an early event in the metastatic process. A reproducible, prognostic budding scoring system based on outcomes in early stage colorectal cancer has not been established. Design One hundred twenty-eight T3N0M0 colorectal carcinoma patients with known outcome were identified. Tumor budding was defined as isolated tumor cells or clusters of <5 cells at the invasive tumor front. Tumor bud counts were generated in 5 regions at 200× by 2 pathologists (conventional bud count method). The median bud count per case was used to divide cases into low (median=0) and high budding (median ≥1) groups. Forty cases were reevaluated to assess reproducibility using the conventional and a novel rapid bud count method. Results Fifty-seven (45%) carcinomas had high and 71 (55%) had low budding scores. High budding was associated with an infiltrative growth pattern (P<0.0001) and lymphovascular invasion (P=0.005). Five-year cancer-specific survival was significantly poorer in high compared with low budding groups: 63% versus 91%, respectively, P<0.0001. Multivariate analysis demonstrated tumor budding to be independently prognostic (hazard ratio=4.76, P<0.001). Interobserver agreement was at least equivalent comparing the conventional to the rapid bud count methods: 87.5% agreement (κ=0.75) versus 92.5% agreement (κ=0.85), respectively. Conclusions Tumor budding is a strong, reproducible, and independent prognostic marker of outcome that is easily assessed on hematoxylin and eosin slides. This may be useful for identifying the subset of T3N0M0 patients at high risk of recurrence who may benefit from adjuvant therapy.

Development and Independent Validation of a Prognostic Assay for Stage II Colon Cancer Using Formalin-Fixed Paraffin-Embedded Tissue

PURPOSE Current prognostic factors are poor at identifying patients at risk of disease recurrence after surgery for stage II colon cancer. Here we describe a DNA microarray-based prognostic assay using clinically relevant formalin-fixed paraffin-embedded (FFPE) samples. PATIENTS AND METHODS A gene signature was developed from a balanced set of 73 patients with recurrent disease (high risk) and 142 patients with no recurrence (low risk) within 5 years of surgery. RESULTS The 634-probe set signature identified high-risk patients with a hazard ratio (HR) of 2.62 (P < .001) during cross validation of the training set. In an independent validation set of 144 samples, the signature identified high-risk patients with an HR of 2.53 (P < .001) for recurrence and an HR of 2.21 (P = .0084) for cancer-related death. Additionally, the signature was shown to perform independently from known prognostic factors (P < .001). CONCLUSION This gene signature represents a novel prognostic biomarker for patients with stage II colon cancer that can be applied to FFPE tumor samples.

P-Rex1 is required for efficient melanoblast migration and melanoma metastasis

Metastases are the major cause of death from melanoma, a skin cancer that has the fastest rising incidence of any malignancy in the Western world. Molecular pathways that drive melanoblast migration in development are believed to underpin the movement and ultimately the metastasis of melanoma. Here we show that mice lacking P-Rex1, a Rac-specific Rho GTPase guanine nucleotide exchange factor, have a melanoblast migration defect during development evidenced by a white belly. Moreover, these P-Rex1(-/-) mice are resistant to metastasis when crossed to a murine model of melanoma. Mechanistically, this is associated with P-Rex1 driving invasion in a Rac-dependent manner. P-Rex1 is elevated in the majority of human melanoma cell lines and tumour tissue. We conclude that P-Rex1 has an important role in melanoblast migration and cancer progression to metastasis in mice and humans.

The surgical significance of residual mucosal abnormalities in rectal cancer following neoadjuvant chemoradiotherapy

Local excision of rectal cancer after neoadjuvant chemoradiotherapy (CRT) has been proposed as an alternative to radical surgery in selected patients. However, little is known about the significance of the morphological and histological features of residual tumour.

Tumour Tissue Microenvironment Can Inhibit Dendritic Cell Maturation in Colorectal Cancer

Inflammatory mediators in the tumour microenvironment promote tumour growth, vascular development and enable evasion of anti-tumour immune responses, by disabling infiltrating dendritic cells. However, the constituents of the tumour microenvironment that directly influence dendritic cell maturation and function are not well characterised. Our aim was to identify tumour-associated inflammatory mediators which influence the function of dendritic cells. Tumour conditioned media obtained from cultured colorectal tumour explant tissue contained high levels of the chemokines CCL2, CXCL1, CXCL5 in addition to VEGF. Pre-treatment of monocyte derived dendritic cells with this tumour conditioned media inhibited the up-regulation of CD86, CD83, CD54 and HLA-DR in response to LPS, enhancing IL-10 while reducing IL-12p70 secretion. We examined if specific individual components of the tumour conditioned media (CCL2, CXCL1, CXCL5) could modulate dendritic cell maturation or cytokine secretion in response to LPS. VEGF was also assessed as it has a suppressive effect on dendritic cell maturation. Pre-treatment of immature dendritic cells with VEGF inhibited LPS induced upregulation of CD80 and CD54, while CXCL1 inhibited HLA-DR. Interestingly, treatment of dendritic cells with CCL2, CXCL1, CXCL5 or VEGF significantly suppressed their ability to secrete IL-12p70 in response to LPS. In addition, dendritic cells treated with a combination of CXCL1 and VEGF secreted less IL-12p70 in response to LPS compared to pre-treatment with either cytokine alone. In conclusion, tumour conditioned media strongly influences dendritic cell maturation and function.

Spatial variation of the colonic microbiota in patients with ulcerative colitis and control volunteers

Objectives The relevance of spatial composition in the microbial changes associated with UC is unclear. We coupled luminal brush samples, mucosal biopsies and laser capture microdissection with deep sequencing of the gut microbiota to develop an integrated spatial assessment of the microbial community in controls and UC. Design A total of 98 samples were sequenced to a mean depth of 31 642 reads from nine individuals, four control volunteers undergoing routine colonoscopy and five patients undergoing surgical colectomy for medically-refractory UC. Samples were retrieved at four colorectal locations, incorporating the luminal microbiota, mucus gel layer and whole mucosal biopsies. Results Interpersonal variability accounted for approximately half of the total variance. Surprisingly, within individuals, asymmetric Eigenvector map analysis demonstrated differentiation between the luminal and mucus gel microbiota, in both controls and UC, with no differentiation between colorectal regions. At a taxonomic level, differentiation was evident between both cohorts, as well as between the luminal and mucosal compartments, with a small group of taxa uniquely discriminating the luminal and mucosal microbiota in colitis. There was no correlation between regional inflammation and a breakdown in this spatial differentiation or bacterial diversity. Conclusions Our study demonstrates a conserved spatial structure to the colonic microbiota, differentiating the luminal and mucosal communities, within the context of marked interpersonal variability. While elements of this structure overlap between UC and control volunteers, there are differences between the two groups, both in terms of the overall taxonomic composition and how spatial structure is ascribable to distinct taxa.

Diagnostic reproducibility of tumour budding in colorectal cancer: a multicentre, multinational study using virtual microscopy.

Puppa G, Senore C, Sheahan K, Vieth M, Lugli A, Zlobec I, Pecori S, Wang L M, Langner C, Mitomi H, Nakamura T, Watanabe M, Ueno H, Chasle J, Conley S A, Herlin P, Lauwers G Y & Risio M 
(2012) Histopathology 61, 562–575

Inflammatory pseudotumor of the spleen: A clinicopathologic study of three cases

The clinical and pathologic findings of three cases of splenic inflammatory pseudotumor are described, and differential diagnostic features are discussed. This benign lesion is extremely rare, only four having been previously reported. Inflammatory pseudotumors often pose diagnostic difficulties because they form infiltrative masses which have clinical and gross pathologic features that suggest malignancy. Although these lesions are usually easily recognizable microscopically as benign processes, the admixed component of lymphoid and other hematopoietic cells may sometimes raise the question of a lymphoreticular malignancy, requiring immunohistologic studies for resolution in some cases. Alternatively, pseudotumors may be mistaken for infectious granulomatous processes, sarcoidosis, or hamartomas.