Evaluation of lymphocyte apoptosis in patients with oral cancer

Abstract Objectives To evaluate apoptotic levels of peripheral blood mononuclear cells (PBMCs) and apoptotic regulatory proteins (Bax and Bcl-2) in lymphocyte subsets of oral cancer (OC) patients and healthy controls (HC). Methodology The percentage of apoptotic cells and lymphocyte counts were measured in the first cohort using PBMCs obtained from 23 OC patients and 6 HC. In the second cohort, (OC, 33; HC, 13), the mean fluorescence intensity (MFI) of Bax and Bcl-2 in CD19+ B, CD4+ T, CD8+ T, and CD16+56+ natural killer (NK) cells was determined via flow cytometry. Results The percentage of apoptotic cells was higher in the PBMCs of OC patients than in HC patients, particularly in patients with stage IV cancer (p<0.05). However, lymphocyte counts were significantly lower in stage IV patients (p<0.05). NK CD19+ B and CD16+56+ cell counts were significantly lower in OC patients compared with HC patients (p<0.001 and p<0.01, respectively), but CD4+ T cells were interestingly significantly higher in OC patients (p<0.001). While Bax MFI was slightly higher, Bcl-2 MFI was significantly lower for all four lymphocyte subsets in OC samples, particularly in stage IV patients, when compared with HC. Consequently, Bax/Bcl-2 ratios showed an upward trend from HC to OC patients, particularly those in stage IV. We found similar trends in Bax and Bcl-2 MFI for tumor stage, tumor size, and lymph node involvement. Conclusions The increased lymphocyte apoptosis in stage IV OC patients may be related to higher Bax levels and lower Bcl-2 levels. The Bax/Bcl-2 ratio in lymphocytes may be useful to determine the prognosis of OC patients, and could be considered a mean for supportive treatment in the future.

Connection up- and down-regulation expression analysis of microarrays (CU-DREAM): a physiogenomic discovery tool.

Background: Many microarray experiments have been conducted during recent years, and scores of gene expression data have been archived in public databases. The use of data from multiple experiments can provide valuable information. However, there is a lack of convenient tools to compare datasets in this manner. Objective: Implement software, called CU-DREAM, to compare the datasets of two microarray experiments. CUDREAM is easy to use and compatible with Gene Expression Omnibus (GEO). Subjects and methods: Five experiments were used to demonstrate the functionality of CU-DREAM. These are GSE6791, GSE7803, GSE5816, GSE4246, and GSE13638 for studies of cancers and RNA interference. Results: All six showcases demonstrated the validity of the CU-DREAM approach. One showcase could confirm the regulation of genes identified in two independent experiments on cervical cancer. The statistical significance was lower compared with cervical and lung cancers. In addition, CU-DREAM could identify isoform changes in lung cancer. The last showcase demonstrated that Dicer- and Ago2-depleted cells or Dicer-depleted HeLa and HEK293 cells shared the same gene regulation pathways. CU-DREAM had seven main functions: 1) to identify genes that are up- and down-regulated in an experiment, 2) to validate significantly regulated genes using data from another experiment, 3) to determine if two different diseases have a similar effect on gene regulation, 4) to identify isoform-changed genes, 5) to determine if cells share gene regulation mechanisms, 6) to identify common gene regulation pathways even when comparing two different cell types, and 7) to identify down-stream genes that are regulated by the conditions of the analyzed experiments. Conclusion: CU-DREAM is an effective tool for the pre-screening of drugs, substances or environmental insults or the identification of the genetic changes that are associated with pathological conditions (CU-DREAM can be downloaded from: http://pioneer.netserv.chula.ac.th/~achatcha/cu-dream).

Ataxia telangiectasia mutated nuclear localization in head and neck cancer cells is PPP2R2B-dependent.

Background: Protein phosphatase 2A (PP2A) has been implicated in radiation-induced activation of cellular responses, likely by its ability to regulate the autophosphorylation of the ataxia telangiectasia mutated (ATM) protein, a key molecule involved in the DNA damage response initiated by double-stranded DNA breaks. Interestingly, a hereditary defect in the PPP2R2B gene, which encodes the beta isoform of PP2A regulatory subunit B, causes autosomal dominant spinocerebellar ataxia 12, a clinical condition resembling that of ataxia telangiectasia patients. Moreover, PPP2R2B is significantly downregulated in many human cancers, including head and neck squamous cell carcinomas (HNSCCs). Objective: Examine whether PPP2R2B regulates ATM function, thereby contributing to tumor progression due to the resulting defective DNA repair. Methods: The roles of PPP2R2B were evaluated in irradiated HNSCC cell lines, siRNAPPP2R2B cells and okadaic acid treated cells. Expression of PPP2R2B was measured by microarray, Western blot analysis and real time quantitative rtPCR. ATM quantity and localization, ATM phosphorylation and γ-H2AX were determined by Western blot analysis and/or immunofluorescence assay. Clonogenic cell survival assay was performed to determine ionizing radiation sensitivity. Results: PPP2R2B expression is reduced in multiple tumor types, including HNSCCs. Indeed, HNSCC cell lines that have lower PPP2R2B mRNA expression and siRNAPPP2R2B cells lower basal and radiation-induced levels of phosphorylated ATM and the consequent reduction in the levels of phosphorylation of the downstream ATM target, γ-H2AX. Depletion of PPP2R2B and inhibition of PP2A with okadaic acid resulted in limited ATM nuclear localization. Finally, siRNAPPP2R2B cells displayed enhanced sensitivity to death after radiation. Conclusion: In HNSCCs, ATM nuclear localization is PPP2R2B dependent, and decreased PPP2R2B expression may result in limited ATM activation by preventing its nuclear accumulation and ATM-chromatin interaction. Therefore, decreased PPP2R2B expression in HNSCCs may contribute to genomic instability, cancer development and radiation sensitivity by limiting ATM functions.

Quantitative PCR analysis for methylation level of genome: clinical implications in cancer.

Background: Cancer cells are frequently characterized by hypomethylation of the genome including repetitive sequences. This epigenetic process is believed to be associated with several biological causes and consequences in cancer. Therefore, LINE-1 repetitive sequences demethylation in cancer should result in different clinical outcomes. Objective: Recently, we have developed an improved quantitative combined bisulfite restriction analysis PCR protocol that efficiently evaluates the methylation status of LINE-1s; the method is referred to as PCR “COBRALINE-1”. This article reviewed what have been learned by applying this technique to study methylation level of repetitive sequences from several sources of genomic DNA. Results: We have found that LINE-1 methylation patterns among normal tissues are distinct. Therefore, this epigenetic event may be continuously altered in adult tissues by the process of cellular differentiation. Moreover, we confirmed that global hypomethylation is an ongoing process that develops during tumor progression, in addition to previous evidence of genomic and LINE-1 hypomethylation occurring as an early event in carcinogenesis. COBRALINE-1 is a highly effective technique for evaluating the genome-wide level of methylation, in particular from tissue samples with minute amounts of low quality DNA. The technique has been applied to study samples from micro-dissected archived paraffin-embedded tissues and sera of several types of cancer. Conclusion: The COBRALINE-1 technique demonstrated its potential to be a tumor marker and a great tool to explore the biology of global hypomethylation.

Line-1 hypomethylation in multistage carcinogenesis of the uterine cervix.

OBJECTIVE: To evaluate characteristics of global hypomethylation in evolution of cervical cancer. MATERIALS AND METHODS: Eight cases of squamous cell carcinoma (SCC) and seven cases of carcinoma in situ (CIS) were studied. Each of the SCC samples contained CIS, and all SCC and CIS samples contained normal ectocervical epithelium. Microdissection was performed to separate normal epithelium, CIS and SCC prior to DNA extraction. Hypomethylation levels of long interspersed nuclear elements (LINE-1 or L1) were measured with a combined bisulfite restriction analysis (COBRA) PCR (polymerase chain reaction) protocol. The percentage of L1 hypomethylation for SCC, CIS and normal epithelium was compared. RESULTS: In the SCC cohort, the L1 hypomethylation level showed progressive increase comparing normal epithelium (59.4 +/- 8.86%) to CIS (64.37 +/- 7.32%) and SCC (66.3 +/- 7.26%) (repeated measurement ANOVA, P = 0.005). A significantly greater L1 hypomethylation level was found in CIS (62.06 +/- 3.44 %) compared to normal epithelium (60.03 +/- 3.69 %) (paired t-Test, P = 0.03). No significant difference in L1 hypomethylation level was noted between CIS of the two sample groups (unpaired t-Test, P = 0.2). CONCLUSIONS: In our study, there was a significant correlation between the degree of hypomethylation and progression from normal ectocervical mucosa to CIS and invasive cancer. Laboratory assessment of biopsies for this molecular event may have clinical significance.

Future cancer management with stem cell knowledge and technology.

Cancer has been proposed as a result of abnormal control of growth and development of stem cells for more than century. This is the "cancer stem cell hypothesis". Both cancer and stem cells share many common especial properties. They are immortal and have good differentiation potential. In addition, organogenesis and carcinogenesis are very similar processes. Recently, more evidence and convincing data from stem cell biology research are supporting this concept. Furthermore, the research provides new promising approaches for cancer diagnosis and treatment based on stem cell knowledge and technology. Upcoming data and evidence may revolutionize cancer management, making it more effective and safer.

Histopathologic characteristics of pulmonary adenocarcinomas with and without EGFR mutation.

EGFR mutation played crucial role for responsiveness of non-small cell lung cancers to EGFR tyrosine kinase inhibitors. Almost the mutations were present in adenocarcinomas. Few had studied on histopathologic correlation with EGFR mutation in pulmonary adenocarcinomas. To obtain better view on pathobiology of pulmonary adenocarcinomas, we correlated exons 19 and 21 mutations with various histopathologic features by dissecting particular histological patterns from 60 surgically resected adenocarcinomas. RESULTS: Gland-forming pattern, including bronchiloloalveolar carcinoma (BAC), well-formed acinar, and poorly-formed acinar patterns more frequently contains EGFR mutations than solid pattern (72.7% vs. 23.1%, p = 0.002). EGFR mutations of each within the gland-forming pattern are not significantly different. Micropapillary pattern revealed less exon 19 mutations than the gland-forming pattern (12.5% vs. 66.7%, p = 0.018), but tended to have more Exon 21 mutations than the others (33.3% vs. 11.9%, p = 0.10). Tumors predominated by BAC pattern more commonly had exon 19 mutations than non-BAC predominated tumors (68.8% vs. 39.5%, p = 0.046). EGFR-mutated tumors comprised less proportion of papillary pattern than tumors without mutation (mean = 1.5% vs. 11.2%, p = 0.049). Terminal respiratory unit (TRU) histology was associated with more EGFR mutations (72.4% vs. 42.1%, p = 0.036). Tumors smaller than 3.5 cm had more EGFR mutations than larger tumors (73.1% vs. 41.9%, p = 0.018). CONCLUSION: High frequency of the mutation does not present only in BAC pattern, but also in well-formed and poorly-formed acinar patterns, suggesting them as usual spectrum of EGFR mutated adenocarcinomas. Other characteristics of EGFR-mutated adenocarcinomas include TRU-type histology, smaller size, and less solid phenotype.

Distribution of human leukocyte antigens-E alleles in Thailand.

The aim of this study was to investigate the distribution of human leukocyte antigens (HLA) -E alleles in Thailand. HLA-E alleles were assigned by using a polymerase chain reaction-sequence specific oligonucleotide probes (PCR-SSOP) method and direct sequencing in 200 healthy individuals. They comprised 100 Thai, 50 Chinese and 50 Thai-Chinese. From the results, three alleles of HLA-E could be detected in these populations. The E*0101 was the most common allele in Thai and Thai-Chinese with allelic frequencies of 42.5 per cent and 38 per cent, respectively. The other HLA-E allele frequencies of Thai origin were 33 per cent for E*01031 and 24.5 per cent for E*01032, respectively. Among Thai-Chinese, the allele frequencies of HLA-E were 31 per cent for E*01031 and E*01032, respectively. Whereas, the E*01031 was the predominant allele in Chinese origin with a frequency of 39 per cent, followed by E*0101 and E*01032 with 32 per cent and 29 per cent, respectively. No E*01033, E*0102 and E*0104 could be detected in all individuals. When comparing the distribution of HLA-E alleles between each of the populations (Thai vs Chinese, Thai vs Thai-Chinese and Chinese vs Thai-Chinese), no significant difference could be found among these populations. In addition, there was no significant difference of the distribution of HLA-E alleles between the study populations and other populations from Asian countries, reported previously. However, there were significant differences between the populations (Thai, Chinese and Thai-Chinese) and Danish (chi2 = 15.64, p = 0.0004; chi2 = 24.58, p = 0.0000046; chi2 = 14.69, p = 0.00065, respectively).