Differential gene expression in patients genetically predisposed to pancreatic cancer

Epidrugs: targeting epigenetic marks in cancer treatment

Growing evidence suggests that aberrant epigenetic regulation of gene function is strongly related to the genesis of cancer. Unlike genetic mutations, the ability to reprogram the epigenetic landscape in the cancer epigenome is one of the most promising target therapies in both treatment and reversibility of drug resistance. Epigenetic alterations in cancer development and progression may be the basis for the individual variation in drug response. Thus, this review focuses on the emerging area of pharmaco(epi)genomics, specifically highlighting epigenetic reprogramming during tumorigenesis and how epigenetic markers are targeted as a therapy (epidrugs) and the clinical implications of this for cancer treatment.

Pancreatic cancer early detection: Expanding higher-risk group with clinical and metabolomics parameters

Pancreatic ductal adenocarcinoma (PDAC) is the fourth and fifth leading cause of cancer death for each gender in developed countries. With lack of effective treatment and screening scheme available for the general population, the mortality rate is expected to increase over the next several decades in contrast to the other major malignancies such as lung, breast, prostate and colorectal cancers. Endoscopic ultrasound, with its highest level of detection capacity of smaller pancreatic lesions, is the commonly employed and preferred clinical imaging-based PDAC detection method. Various molecular biomarkers have been investigated for characterization of the disease, but none are shown to be useful or validated for clinical utilization for early detection. As seen from studies of a small subset of familial or genetically high-risk PDAC groups, the higher yield and utility of imaging-based screening methods are demonstrated for these groups. Multiple recent studies on the unique cancer metabolism including PDAC, demonstrate the potential for utility of the metabolites as the discriminant markers for this disease. In order to generate an early PDAC detection screening strategy available for a wider population, we propose to expand the population of higher risk PDAC group with combination clinical and metabolomics parameters.

Proteome of formalin-fixed paraffin-embedded pancreatic ductal adenocarcinoma and lymph node metastases

Pancreatic ductal adenocarcinoma (PDAC) is a major cause of cancer-related death, largely due to metastatic disease. To better understand PDAC metastatic spread and identify novel therapeutic targets, we analysed the proteome of primary tumours and matched lymph node (LN) metastases. As frozen specimens of metastatic lesions are scarce, we examined formalin-fixed paraffin-embedded (FFPE) tissues. This poses technical challenges because of the cross-linkages induced by fixation. Using laser capture microdissection (PALM system), we isolated malignant epithelia from seven FFPE primary PDAC tumours and matched LN metastases. Following dissection, samples were analysed in duplicate using Multidimensional Protein Identification Technology (MudPIT); this resulted in the identification of 1504 proteins, 854 of which were common to all samples analysed. Comparison of the obtained proteins with data from previous proteomics studies on pancreatic tissue, pancreatic juice, serum, and urine resulted in a less than 30% overlap, indicating that our study has substantially expanded the current database of proteins expressed in this malignancy. Statistical analysis further showed that 115/854 proteins (13.5%) were significantly differentially expressed (g-value ≥ 3.8). Two proteins, S100P and 14-3-3 sigma, with highly significant g-values were confirmed to be significantly differentially expressed (S100P: p = 0.05 and 14-3-3 sigma: p < 0.001) in a larger series of 55 cases of matched primary PDAC and LN metastases using immunohistochemistry. Thus, laser capture microdissection of FFPE tissue coupled with downstream proteomic analysis is a valid approach for the investigation of metastatic PDAC. This is the first study to establish and compare the protein composition of primary PDAC and matched LN metastases, and has resulted in the identification of several potential epithelial-specific therapeutic targets, including 14-3-3 sigma and S100P.

Review of screening for pancreatic cancer in high risk individuals

Pancreatic cancer is difficult to diagnose at an early stage and is associated with a very poor survival. Ten percent of pancreatic cancers result from genetic susceptibility and/or familial aggregation. Individuals from families with multiple affected first-degree relatives and those with a known cancer-causing genetic mutation have been shown to be at much higher risk of developing pancreatic cancer. Recent efforts have focused on detecting disease at an earlier stage to improve survival in these high-risk groups. This article reviews high-risk groups, screening methods, and current screening programs and their results.

Pancreatic cancer surveillance among high-risk populations: knowledge and intent

Pancreatic cancer is the fourth most common cancer in both men and women in the United States. It has the lowest survival rate of all cancers, largely due to the presence of non-specific symptoms, leading to diagnosis at advanced stages. While the majority of cases of pancreatic cancer are sporadic, up to 10% may be associated with an inherited predisposition. Currently, there is no standard screening protocol for pancreatic cancer, although this will change in the future as technology improves. Additionally, there is little information regarding the perceptions and intent to screen for pancreatic cancer among those with an increased risk due to a hereditary cancer predisposition syndrome, which was the objective of this study. Focus groups and individual telephone interviews were conducted, with questions focused on knowledge about pancreatic cancer and screening, perceived motivators, and perceived barriers related to each of the screening techniques currently available. Participants were recruited from the High Risk Breast Cancer and Pancreatic Cancer Registries at Huntsman Cancer Institute. The findings of this study indicated that individuals from these high-risk groups have low knowledge levels of pancreatic cancer screening, despite their desire for this information. Motivation to undergo a particular screening technique is related to whether the test is recommended by a physician, cost, degree of invasiveness, and comfort level. This information is useful to genetics professionals who counsel at-risk individuals, physicians who formulate patient care plans, and translational researchers who are developing pancreatic screening methods.

Comparative expression analysis of isolated human adipocytes and the human adipose cell lines LiSa-2 and PAZ6

OBJECTIVE

To obtain insight in the extent to which the human cell lines LiSa-2 and PAZ6 resemble isolated primary human adipocytes.

DESIGN

A combination of cDNA subtraction (representative difference analysis; RDA) and cDNA microarray analysis was used to select adipose specific genes to compare isolated (pre-)adipocytes with (un)differentiated LiSa-2 and PAZ6 cells.

MEASUREMENTS

RDA was performed on adipose tissue against lung tissue. A total of 1400 isolated genes were sequenced and cDNA microarray technology was used for further adipose related gene selection. 30 genes that were found to be enriched in adipose tissue were used to compare isolated human adipocytes and LiSa-2 and PAZ6 cells in the differentiated and undifferentiated states.

RESULTS

RDA and microarray analysis resulted in the identification of adipose enriched genes, but not in adipose specific genes. Of the 30 most differentially expressed genes, as expected, most were related to lipid metabolism. The second category consisted of methyltransferases, DNMT1, DNMT3a, RNMT and SHMT2, of which the expression was differentiation dependent and higher in differentiated adipocytes. Using the 30 adipose expressed genes, it was found that isolated adipocytes on one hand, and PAZ6 and LiSa-2 adipocytes on the other, differ primarily in lipid metabolism. Furthermore, LiSa-2 cells seem to be more similar to isolated adipocytes than PAZ6 cells.

CONCLUSION

The LiSa-2 cell line is a good model for differentiated adipocytes, although one should keep in mind that the lipid metabolism in these cells deviates from the in vivo situation Furthermore, our results imply that methylation may have an important function in terminal adipocyte differentiation.