Platform-independent gene expression signature differentiates sessile serrated adenomas/polyps and hyperplastic polyps of the colon.

BACKGROUND: Sessile serrated adenomas/polyps are distinguished from hyperplastic colonic polyps subjectively by their endoscopic appearance and histological morphology. However, hyperplastic and sessile serrated polyps can have overlapping morphological features resulting in sessile serrated polyps diagnosed as hyperplastic. While sessile serrated polyps can progress into colon cancer, hyperplastic polyps have virtually no risk for colon cancer. Objective measures, differentiating these types of polyps would improve cancer prevention and treatment outcome. METHODS: RNA-seq training data set and Affimetrix, Illumina testing data sets were obtained from Gene Expression Omnibus (GEO). RNA-seq single-end reads were filtered with FastX toolkit. Read mapping to the human genome, gene abundance estimation, and differential expression analysis were performed with Tophat-Cufflinks pipeline. Background correction, normalization, and probe summarization steps for Affimetrix arrays were performed using the robust multi-array method (RMA). For Illumina arrays, log2-scale expression data was obtained from GEO. Pathway analysis was implemented using Bioconductor package GSAR. To build a platform-independent molecular classifier that accurately differentiates sessile serrated and hyperplastic polyps we developed a new feature selection step. We also developed a simple procedure to classify new samples as either sessile serrated or hyperplastic with a class probability assigned to the decision, estimated using Cantelli's inequality. RESULTS: The classifier trained on RNA-seq data and tested on two independent microarray data sets resulted in zero and three errors. The classifier was further tested using quantitative real-time PCR expression levels of 45 blinded independent formalin-fixed paraffin-embedded specimens and was highly accurate. Pathway analyses have shown that sessile serrated polyps are distinguished from hyperplastic polyps and normal controls by: up-regulation of pathways implicated in proliferation, inflammation, cell-cell adhesion and down-regulation of serine threonine kinase signaling pathway; differential co-expression of pathways regulating cell division, protein trafficking and kinase activities. CONCLUSIONS: Most of the differentially expressed pathways are known as hallmarks of cancer and likely to explain why sessile serrated polyps are more prone to neoplastic transformation than hyperplastic. The new molecular classifier includes 13 genes and may facilitate objective differentiation between two polyps.

Cystoisospora belli Infection of the Gallbladder in Immunocompetent Patients: A Clinicopathologic Review of 18 Cases.

Cystoisospora belli, previously known as Isospora belli, is an obligate intracellular coccidian parasite that is most often associated with gastrointestinal disease in immunocompromised patients. In this study, we detail the clinicopathologic features of 18 cases of Cystoisospora infection affecting the gallbladder in immunocompetent individuals and compare them with a control group. Each case was reviewed for cholecystitis (none, acute, chronic), epithelial disarray, presence of intraepithelial lymphocytes (none, rare [≤5 per 20 epithelial cells], present [>5 per 20 epithelial cells]), architectural distortion, intramucosal eosinophilia, and mural thickening/serositis. The mean age of patients with Cystoisospora infection was 33 years and the male to female ratio 1:4.3. Cholecystectomy was performed for biliary dyskinesia (n=7), abdominal pain (n=7), suspected cholelithiasis (n=5), and cholecystitis (n=3). In 2 cases, Cystoisospora was found in donor gallbladders resected at the time of liver transplantation. Each case was characterized by eosinophilic, oval or banana-shaped intraepithelial parasites within perinuclear parasitophorous vacuoles. Most cases showed epithelial disarray and minimal intraepithelial lymphocytosis. Of the 11 cases with an average follow-up of 15 months, none had evidence of disease related to Cystoisospora infection within the biliary tract or elsewhere in the gastrointestinal tract. We present the largest series of gallbladder cystoisosporiasis in immunocompetent patients to date. Cystoisospora infection is underrecognized in the gallbladders of immunocompetent patients, in part due to the subtle findings in routine cholecystectomy specimens. On the basis of the clinical follow-up, gallbladder cystoisosporiasis in immunocompetent individuals appears to be a self-limited infection.

Gastric Proteins MUC5AC and TFF1 as Potential Diagnostic Markers of Colonic Sessile Serrated Adenomas/Polyps.

OBJECTIVES: A subset of colon cancers originates from sessile serrated adenomas/polyps (SSA/Ps). Our goal was to identify markers for SSA/Ps that could aid in distinguishing them from hyperplastic polyps (HPs). METHODS: We performed immunostaining for gastric proteins MUC5AC and TFF1 in formalin-fixed, paraffin-embedded (FFPE) samples of HPs (n = 47), SSA/Ps (n = 37), and normal colon (n = 30). RESULTS: Control mucosa expressed only trace amounts of MUC5AC and TFF1. HPs exhibited an 11.3- and 11.4-fold increase in MUC5AC and TFF1 expression confined to the upper segments of the crypts near the luminal surface of the polyps. SSA/Ps displayed on average 1.6-fold (MUC5AC, P < .008) and 1.4-fold (TFF1, P < .03) higher signal intensity for these markers than HPs, with a dramatic coexpression of MUC5AC and TFF1 typically occupying the entire length of the crypt. Immunoperoxidase results were similar to immunofluorescence staining for both MUC5AC and TFF1. CONCLUSIONS: Our results suggest that the analysis of expression of MUC5AC and TFF1 may be useful for differentiating SSA/Ps from HPs. We also suggest the possibility that crypt morphology may be at least partly due to overproduction of highly viscous gastric mucins and that these proteins may play a role in the serrated pathway to colon carcinogenesis.

Ovarian tumor ascites CD14+ cells suppress dendritic cell-activated CD4+ T-cell responses through IL-10 secretion and indoleamine 2,3-dioxygenase.

The observation that Th17 infiltration in ovarian cancer correlates with markedly improved survival has prompted the question of whether ovarian tumor antigen-specific Th17 responses could be stimulated by tumor vaccination. Dendritic cells (DCs) treated with IL-15 and an inhibitor of p38 MAPK signaling (DC(IL-15/p38inhib)) bias T-cell responses toward a Th1/Th17 phenotype, raising the prospect of therapeutic vaccination; however, significant barriers remain. Tumor vaccines, including DC vaccination, usually stimulate immune responses, but the lack of clinical responses in cancer patients has been disappointing. Possible reasons may include an inability of antitumor T cells to migrate into the tumor microenvironment, and an inability of T cells to retain effector function in the face of tumor-associated immune suppression. We found that ovarian tumor antigen-specific CD4(+) T cells induced by DC(IL-15/p38inhib) migrated in response to CXCL12 and CCL22 (both highly expressed in ovarian cancer) and to ascites CD14(+) myeloid cells. Cocultures showed that ascites CD14(+) cells markedly suppressed antigen-specific CD4(+) T responses, but suppression could be alleviated by treatment with anti-IL-10 or inhibition of indoleamine 2,3-dioxygenase. These results suggest that the efficacy of DC vaccination against ovarian cancer may be boosted by agents that inhibit tumor-associated CD14(+) myeloid cell suppression or indoleamine 2,3-dioxygenase activity.

Dendritic cell vaccination, immune regulation, and clinical outcomes in ovarian cancer.

Clinical optimism for dendritic cell vaccination against ovarian cancer has been tempered by the knowledge that tumors avail themselves of multiple mechanisms of immune evasion, thus blunting the efficacy of therapeutic vaccination. Mechanisms of immune suppression include infiltration by regulatory T cells (Treg) and myeloid suppressor cell populations, expression of co-inhibitory receptors, and expression of indoleamine 2,3-dioxygenase (IDO). Expression of both B7-H1 and IDO are associated with differentiation and recruitment of Treg, and clinical studies have shown that each of these mechanisms correlates independently with increased morbidity and mortality in ovarian cancer patients. In sharp contrast, recent studies have indicated that Th17 cell infiltration in ovarian cancer correlates with improved patient outcomes and prolonged overall survival. Given that IDO plays a pivotal role in the balance between Treg and Th17 immunity, elucidation of the mechanisms that regulate IDO activity and immune suppression may lead to novel adjuvants to boost the clinical efficacy of dendritic cell vaccination against ovarian cancer and other malignancies.

Modulation of p38 MAPK signaling enhances dendritic cell activation of human CD4+ Th17 responses to ovarian tumor antigen.

The recent finding that Th17 infiltration of ovarian tumors positively predicts patient outcomes suggests that Th17 responses play a protective role in ovarian tumor immunity. This observation has led to the question of whether Th17 cells could be induced or expanded to therapeutic advantage by tumor vaccination. In this study, we show that treatment of ovarian tumor antigen-loaded, cytokine-matured human dendritic cells (DC) with a combination of IL-15 and a p38 MAP kinase inhibitor offers potent synergy in antagonism of CD4(+) Treg induction and redirection toward CD4(+) Th17 responses that correlate with strong CD8(+) cytotoxic T lymphocyte (CTL) activation. Ovarian tumor antigen-specific CD4(+) T cells secrete high levels of IL-17 and show reduced expression of CTLA-4, PD-1, and Foxp3 following activation with IL-15/p38 inhibitor-treated DC. We further show that modulation of p38 MAPK signaling in DC is associated with reduced expression of B7-H1 (PD-L1), loss of indoleamine 2,3-dioxygenase activity, and increased phosphorylation of ERK 1/2 MAPK. These observations may allow the development of innovative DC vaccination strategies to boost Th17 immunity in ovarian cancer patients.

The case for HER2/neu as a therapeutic target for gynecologic malignancies.

Evaluation of: Guzzo F, Bellone S, Buza N et al. HER2/neu as a potential target for immunotherapy in gynecological carcinosarcomas. Int. J. Gynecol. Pathol. 31, 211-221 (2012). Trastuzumab (Herceptin(®)) is a human monoclonal antibody that is US FDA-approved for the treatment of HER2/neu-overexpressing breast cancer and metastatic gastric cancer. HER2/neu expression has also been observed in other malignancies, notably in subsets of endometrial and ovarian cancers, raising the possibility that trastuzumab may be a viable treatment option in these settings. The current paper reveals that HER2/neu may also be expressed in gynecologic carcinosarcomas, which are rare but aggressive tumors with a high rate of resistance to chemotherapy. Cell lines derived from ovarian carcinosarcomas expressed HER2/neu and were sensitive to trastuzumab ADCC. By contrast, cell lines derived from uterine carcinosarcomas were HER2/neu-negative and insensitive to trastuzumab ADCC. These observations indicate that at least a subset of gynecologic carcinosarcoma patients may benefit from trastuzumab treatment. However, trastuzumab monotherapy typically has relatively low response rates, which in part may be related to impaired NK cell function in patients with advanced disease. Accordingly, treatments that boost NK cell activity may improve response rates to trastuzumab treatment, not only for gynecologic carcinosarcomas, but also for other HER2/neu-positive malignancies.