Microarray gene expression analysis was successfully used to predict complete responses to preoperative chemoradiotherapy in patients with advanced rectal cancer.

Background: Elucidating the molecular mechanisms by which tumors become resistant to Herceptin is critical for the treatment of Her2-overexpressed metastatic breast cancer.

Recently, RASSF2A was identified as a potential tumor suppressor epigenetically inactivated in human cancers. Here, we evaluated the methylation status of RASSF2A in colorectal cancer (CRC) and analyzed its correlation with K-ras/BRAF mutations, microsatellite instability status and other clinicopathological features. Using methylation-specific PCR and bisulfite sequencing, we analyzed the methylation status in primary CRC, adenomas and corresponding normal tissues and then compared it with the presence of K-ras and BRAF mutations. We also examined the expression and methylation status of RASSF2A in CRC cell lines. We found that aberrant methylation of RASSF2A promoter regions is associated with gene silencing in CRC cell lines. In primary CRC, the frequency of RASSF2A methylation was 72.6%, and it was found in 16 of 16 (100%) adenomas. In addition, there was a positive correlation between K-ras/BRAF mutations and RASSF2A methylation in primary CRC. Furthermore, a significant positive correlation between K-ras/BRAF mutations and RASSF2A methylation was also observed in microsatellite-stable (p 5 0.033) and distal CRC (p 5 0.025). These results show that RASSF2A methylation is a frequent event in colorectal tumorigenesis and positively correlates with K-ras/BRAF mutation in microsatellite-stable or distal CRC. ' 2006 Wiley-Liss, Inc.Key words: RASSF2A; methylation; K-ras; BRAF; microsatellite stability Accumulation of genetic alterations is associated with the development of cancer. The multistep carcinogenesis model in colon cancer serves as the classical model of genetic alterations in cancer.1 Colorectal cancer (CRC) is initiated by alterations in molecules in the Wnt, TGF-b signaling pathways and K-ras and TP53.2 Together with the accumulation of genetic alterations, epigenetic alterations also result in the transformation of normal colon epithelium into adenocarcinoma.3 Analysis of the methylation profiles of colon cancer cell lines and primary tumors show that multiple tumor suppressor genes are methylated and participate in the development of CRC. 4 The Ras signaling pathway plays an important role in tumorigenesis, and mutation of the ras gene is found frequently in many tumor types including CRC.5 The Ras-GTPase controls cell fate through the binding of effector molecules such as Raf and PI3 kinase. Mutations of K-ras and BRAF that activate the Ras/Raf/ MAPK pathway are frequent oncogenic events in sporadic CRC. V600 is a hotspot for mutation of BRAF, and the V600E mutation accounts for more than 80% of the BRAF mutations in CRC.6 In addition, the K-ras mutation is detected in up to 50% of large bowel adenocarcinomas. 7,8 The BRAF V600E and K-ras mutations are known to be mutually exclusive. 9,10Recently, Khokhlatchev et al. identified another Ras effector pathway, wherein active K-ras initiates apoptosis through the direct recruitment of the effector NORE.11 NORE1 (RASSF5) interacts with RASSF1, another Ras effector, and has tumor suppressor activity.12 Methylation of the RASSF1 gene has been reported ...

BackgroundNon-Hodgkin lymphoma (NHL) is a hematologic malignancy for which good diagnostic markers are lacking. Despite continued improvement in our understanding of NHL, efforts to identify diagnostic markers have yielded dismal results. Here, we translated low-mass-ion information in urine samples from patients with NHL into a diagnostic marker.MethodsTo minimize experimental error, we tested variable parameters before MALDI-TOF analysis of low-mass ions in urine. Urine from 30 controls and 30 NHL patients was analyzed as a training set for NHL prediction. All individual peak areas were normalized to total area up to 1000 m/z. The training set analysis was repeated four times. Low-mass peaks that were not affected by changes in experimental conditions were collected using MarkerView™ software. Human Metabolome Database (HMDB) searches and ESI LC-MS/MS analyses were used to identify low-mass ions that exhibited differential patterns in control and NHL urines. Identified low-mass ions were validated in a blinded fashion in 95 controls and 66 NHL urines to determine their ability to discriminate NHL patients from controls.ResultsThe 30 highest-ranking low-mass-ion peaks were selected from the 60-urine training set, and three low-mass-ion peaks with high intensity were selected for identification. Of these, a 137.08-m/z ion showed lower mass-peak intensity in urines of NHL patients, a result that was validated in a 161-urine blind validation set (95 controls and 66 NHL urines). The 130.08-m/z ion was identified from HMDB searches and ESI LC-MS/MS analyses as hypoxanthine (HX). The HX concentration in urines of NHL patients was significantly decreased (P < 0.001) and was correlated with the mass-peak area of the 137.08-m/z ion. At an HX concentration cutoff of 17.4 μM, sensitivity and specificity were 79.2% and 78.4%, respectively.ConclusionsThe present study represents a good example of low-mass-ion profiling in the setting of disease screening using urine. This technique can be a powerful non-invasive diagnostic tool with high sensitivity and specificity for NHL screening. Furthermore, HX identified in the study may be a useful single urine marker for NHL screening.

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