Immunohistochemical detection of 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, in human chronic cholecystitis

A double-blind, randomized, neoadjuvant study of the tissue effects of POMx pills in men with prostate cancer before radical prostatectomy

Pomegranates slow prostate cancer xenograft growth and prolong prostate-specific antigen (PSA) doubling times in single-arm human studies. Pomegranates' effects on human prostate tissue are understudied. We hypothesized that orally administered pomegranate extract (POMx; Pom Wonderful) would lower tissue 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative stress biomarker. Seventy men were randomized to two tablets, POMx or placebo, daily up to four weeks before radical prostatectomy. Tissue was analyzed for intraprostatic urolithin A, a pomegranate metabolite, benign and malignant 8-OHdG, and cancer pS6 kinase, NF-κB, and Ki67. Primary endpoint was differences in 8-OHdG, and the study was powered to detect 35% reduction. POMx was associated with 16% lower benign tissue 8-OHdG (P = 0.095), which was not statistically significant. POMx was well tolerated with no treatment-related withdrawals. There were no differences in baseline clinicopathological features between arms. Urolithin A was detected in 21 of the 33 patients in the POMx group versus 12 of the 35 in the placebo group (P = 0.031). Cancer pS6 kinase, NF-κB, Ki67, and serum PSA changes were similar between arms. POMx before surgery results in pomegranate metabolite accumulation in prostate tissues. Our primary endpoint in this modest-sized short-term trial was negative. Future larger longer studies are needed to more definitively test whether POMx reduces prostate oxidative stress, as well as further animal testing to better understand the multiple mechanisms through which POMx may alter prostate cancer biology.

Acute cholecystitis in end-stage renal disease patients: a nation-wide longitudinal study

BACKGROUND

The objective of this study was to evaluate the risks of acute cholecystitis among end-stage renal disease patients and compare the incidence between two dialysis modality.

STUDY DESIGN

In this retrospective cohort study, records of fifty thousand end-stage renal disease patients older than 20 years of age from 1998 to 2007 and an age, gender, Charlson's score, diabetes, and dyslipidemia matched control cohort were retrieved from Taiwan National Health Insurance Research Database. Hospitalizations for acute cholecystitis were retrieved using ICD-9-CM diagnosis codes and ICD-9-CM operation codes from in-patient claims.

RESULTS

The incidence rates were 5.8 per 1000 patient-years in the end-stage renal disease patients and 0.92 per 1000 patient-years in the control group. End-stage renal disease was an independent risk factor for acute cholecystitis. In the end-stage renal disease patients, independent risk factors were old age, higher Charlson's score, diabetes, severe liver disease, atrial fibrillation, and haemodialysis (all p<0.05). However, the peritoneal dialysis patients had a higher mortality rate after developing acute cholecystitis.

CONCLUSION

Acute cholecystitis is not uncommon in end-stage renal disease patients. The independent risk factors were older age, higher Charlson's score, atrial fibrillation, severe liver disease, diabetes, and dialysis modality. Haemodialysis patients had a higher risk of acute cholecystitis than PD patients.

Immunochemical detection of oxidatively damaged DNA

Oxidatively damaged DNA is implicated in various diseases, including neurodegenerative disorders, cancer, diabetes, cardiovascular and inflammatory diseases as well as aging. Several methods have been developed to detect oxidatively damaged DNA. They include chromatographic techniques, the Comet assay, (32)P-postlabelling and immunochemical methods that use antibodies to detect oxidized lesions. In this review, we discuss the detection of 8-oxo-7,8-dihydro-29-deoxyguanosine (8-oxodG), the most abundant oxidized nucleoside. This lesion is frequently used as a marker of exposure to oxidants, including environmental pollutants, as well as a potential marker of disease progression. We concentrate on studies published between the years 2000 and 2011 that used enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry to detect 8-oxodG in humans, laboratory animals and in cell lines. Oxidative damage observed in these organisms resulted from disease, exposure to environmental pollutants or from in vitro treatment with various chemical and physical factors.

Microfluidic tool based on the antibody-modified paramagnetic particles for detection of 8-hydroxy-2'-deoxyguanosine in urine of prostate cancer patients

Guanosine derivatives are important for diagnosis of oxidative DNA damage including 8-hydroxy-2'-deoxyguanosine (8-OHdG) as one of the most abundant products of DNA oxidation. This compound is commonly determined in urine, which makes 8-OHdG a good non-invasive marker of oxidation stress. In this study, we optimized and tested the isolation of 8-OHdG from biological matrix by using paramagnetic particles with an antibody-modified surface. 8-OHdG was determined using 1-naphthol generated by alkaline phosphatase conjugated with the secondary antibody. 1-Naphthol was determined by stopped flow injection analysis (SFIA) with electrochemical detector using a glassy carbon working electrode and by stationary electrochemical detection using linear sweep voltammetry. A special modular electrochemical SFIA system which needs only 10  μL of sample including working buffer for one analysis was completely designed and successfully verified. The recoveries in different matrices and analyte concentration were estimated. Detection limit (3 S/N) was estimated as 5  pg/mL of 8-OHdG. This method promises to be very easily modified to microfluidic systems as "lab on valve". The optimized method had sufficient selectivity and thus could be used for determination of 8-OHDG in human urine and therefore for estimation of oxidative DNA damage as a result of oxidation stress in prostate cancer patients.

Altered expression of MUTYH and an increase in 8-hydroxydeoxyguanosine are early events in ulcerative colitis-associated carcinogenesis

8-Hydroxy-guanine (8-OH-G) mismatches readily with adenine residues, leading to a G : C to T : A transversion mutation. The human mutY homologue (MUTYH) excises adenine misincorporated opposite 8-OH-G during replication and suppresses mutations caused by reactive oxygen species. We defined the expression of 8-hydroxydeoxyguanosine (8-OHdG) and MUTYH in ulcerative colitis (UC)-associated neoplasia by immunohistochemistry and compared this with expression in UC patients without neoplasia and patients unaffected by UC. We also performed mutation analyses for MUTYH and K-ras. 8-OHdG was expressed more intensely in the mucosa of UC-associated neoplasia and UC without neoplasm than in the mucosa unaffected by UC. Immunohistochemistry with two different types of MUTYH antibody showed that UC-associated neoplasia and UC without neoplasia exhibited strong cytoplasmic expression and attenuated nuclear expression of MUTYH when compared with patients unaffected by UC. No pathological MUTYH mutations were detected in any of the UC-associated neoplasia cases. However, K-ras mutation was detected in two cases, one of which showed G : C to T : A transversion mutation and attenuated nuclear staining of MUTYH. In conclusion, inflamed mucosa of UC is exposed to oxidative damage. An increase in cytoplasmic MUTYH, rather than its mutation, may contribute to the promotion of carcinogenesis in UC.

Cytoplasmic fine granular expression of 8-hydroxydeoxyguanosine reflects early mitochondrial oxidative DNA damage in nonalcoholic fatty liver disease

To clarify the possible role of oxidative stress in hepatocytes in nonalcoholic fatty liver disease, the hepatic expression of 8-hydroxydeoxyguanosine (8-OHdG), a good marker of oxidative DNA damage, was immunohistochemically investigated in nonalcoholic steatohepatitis (NASH) and steatosis. In double immunostaining, the cytoplasmic fine granular 8-OHdG expression was considered to reflect 8-OHdG-positive mitochondrial DNA affecting oxidation stress. In steatosis, 4 of 8 cases showed cytoplasmic 8-OHdG, 1 case showed nuclear 8-OHdG and 1 case showed both cytoplasmic and nuclear 8-OHdG. In contrast, 8-OHdG expression was more frequently detected in NASH (12 of 13 cases, 92%). Immunoreactivity for 8-OHdG was observed only in the cytoplasm with a fine granular pattern (1 of 13 cases, 8%), only in the nucleus (6 of 13 cases, 46%), and in both the cytoplasm and the nucleus (5 of 13 cases, 38%). Megamitochondria also exhibited 8-OHdG intensely. We indicate that 8-OHdG expression in the cytoplasm with a fine granular pattern reflects oxidative damage to the mitochondrial DNA of hepatocytes in both NASH and steatosis. We propose herein that the evaluation of cytoplasmic 8-OHdG may be a sensitive diagnostic marker of early nonalcoholic fatty liver disease events.

Di(2‐ethylhexyl)phthalate Induces Hepatic Tumorigenesis through a Peroxisome Proliferator‐activated Receptor α‐independent Pathway

Di(2-ethylhexyl)phthalate (DEHP), a commonly used industrial plasticizer, causes liver tumorigenesis presumably via activation of peroxisome proliferator-activated receptor alpha (PPARalpha). The mechanism of DEHP tumorigenesis has not been fully elucidated, and to clarify whether DEHP tumorigenesis is induced via PPARalpha, we compared DEHP-induced tumorigenesis in wild-type and Pparalpha-null mice. Mice of each genotype were divided into three groups, and treated for 22 months with diets containing 0, 0.01 or 0.05% DEHP. Surprisingly, the incidence of liver tumors was higher in Pparalpha-null mice exposed to 0.05% DEHP (25.8%) than in similarly exposed wild-type mice (10.0%). These results suggest the existence of pathways for DEHP-induced hepatic tumorigenesis that are independent of PPARalpha. The levels of 8-OHdG increased dose-dependently in mice of both genotypes, but the degree of increase was higher in Pparalpha-null than in wild-type mice. NFkappaB levels also significantly increased in a dose-dependent manner in Pparalpha-null mice. The protooncogene c-jun-mRNA was induced, and c-fos-mRNA tended to be induced only in Pparalpha-null mice fed a 0.05% DEHP-containing diet. These results suggest that increases in oxidative stress induced by DEHP exposure may lead to the induction of inflammation and/or the expression of protooncogenes, resulting in a high incidence of tumorigenesis in Pparalpha-null mice.

Oxidative stress and DNA hypermethylation status in renal cell carcinoma arising in patients on dialysis

Renal cell carcinoma (RCC) is more frequently observed in patients on dialysis than in patients with normal renal function. However, the mechanism underlying carcinogenesis in RCC patients on dialysis is still unclear. We hypothesized that oxidative stress affects patients on dialysis and generates new neoplasms, and therefore analysed the correlation between the influences of various markers of oxidative stress and carcinogenesis in those patients. We evaluated the immunohistochemical expression of oxidative stress markers, such as iNOS, 8-OHdG, and COX-2 in 42 cases on dialysis and 51 cases with normal renal function as a control. The methylation status of p16INK4a, p14ARF, VHL, and RASSF1A was analysed together with clinicopathological factors. Histologically, the papillary type was observed more frequently in dialysis RCC than in sporadic RCC. Immunohistochemically, overexpression of iNOS (p < 0.0001) and COX-2 (p = 0.0002) was more frequently observed in dialysis RCC. Furthermore, the 8-OHdG labelling index was significantly higher in dialysis RCC than in sporadic RCC. Hypermethylation of p16INK4a was more frequently found in dialysis RCC (p < 0.05). However, no significant correlations between oxidative stress markers and DNA hypermethylation status were observed. The overexpression of iNOS, COX-2, and 8-OHdG in dialysis RCC suggests that patients on dialysis are affected by oxidative stress and that this effect plays an important role in the genesis of dialysis RCC.

Immune activation and chronic inflammation as the cause of malignancy in oral lichen planus: is there any evidence ?

The association of chronic inflammation with a variety of epithelial malignancies has been recognised for centuries. Well established examples include, among many others, oesophageal adenocarcinoma associated with chronic oesophagitis and bowel cancer associated with chronic inflammatory bowel diseases. By now no data, other than clinical observation, have been available in understanding the pathogenesis of these inflammation-related tumours. However, recent molecular studies on the relationship between solid malignancies and the surrounding stroma have given new insights. There is now enough evidence to accept that the chronic inflammatory process per se is able to provide a cytokine-based microenvironment which is able to influence cell survival, growth, proliferation, differentiation and movement, hence contributing to cancer initiation, progression, invasion and metastasis. Here it is discussed whether also oral lichen planus (OLP), being a chronic inflammatory autoimmune disease which has been clinically associated with development of oral squamous cell carcinoma, might be categorised among these disorders. With this aim, we critically reviewed and detailed the presence, in OLP subepithelial infiltrate, of inflammatory cells and cytokine networks that might act to promote squamous tumorigenesis.

Detection of oxidative DNA damage in oesophageal biopsies of patients with reflux symptoms and normal pH monitoring

BACKGROUND

Gastro-oesophageal reflux has been shown to induce oxidative DNA damage.

AIM

To determine whether oxidative DNA damage, detected in oesophageal biopsies by simple immunohistochemical staining, correlates with gastro-oesophageal reflux disease as determined by pH monitoring.

METHODS

The study included 47 patients with reflux symptoms who had oesophageal biopsy and 24-h pH monitoring studies performed within 3 months of each other with no variation in treatment in the time between the two procedures. Sections of formalin-fixed and paraffin-embedded oesophageal biopsies were stained for 8-hydroxy-2'-deoxyguanosine using the standard immunoperoxidase method. Positive nuclear immunoreactivity was considered to indicate oxidative DNA damage.

RESULTS

Seven (33%) of the 21 cases with normal 24-h pH monitoring results were negative for oxidative DNA damage, compared with only two (8%) of the 26 cases with abnormal 24-h pH results (P=0.058, two-sided Fisher's exact test). Five of the patients with normal 24-h pH results had oesophageal biopsies performed within 24 h of the monitoring procedure and, of these, four (80%) were positive for oxidative DNA damage, including a case in which both biopsy and 24-h pH monitoring were performed on the same day whilst the patient was on proton pump inhibitor therapy. All cases with normal 24-h pH results and positive oxidative DNA damage showed features of reflux on routine morphological evaluation.

CONCLUSIONS

Oxidative DNA damage can occur in the absence of acid reflux and despite adequate antisecretory therapy. This may indicate that other agents, such as bile, can induce oxidative DNA damage in an acid-suppressed environment. The significant discordance between oxidative DNA damage and 24-h pH results makes the determination of oxidative DNA damage a poor surrogate marker for 24-h pH monitoring.