Oxidative DNA damage in human esophageal cancer: clinicopathological analysis of 8-hydroxydeoxyguanosine and its repair enzyme

Both internal and external oxidative stresses act on DNA and can induce carcinogenesis. 8-hydroxydeoxyguanosine (8-OHdG) is an indicator of oxidative stress and it leads to transversion mutations and carcinogenesis. 8-OHdG is excision-repaired by 8-OHdG DNA glycosylase (OGG1). The purpose of this study is to clarify the effect of oxidative DNA damage and repair enzymes on esophageal carcinogenesis. The levels of 8-OHdG and OGG1 were immunohistochemically evaluated in resected specimens, including squamous cell carcinoma (SCC) in 97 patients with esophageal cancer. Higher levels of 8-OHdG in normal esophageal epithelium were associated with a higher smoking index (P = 0.0464). The 8-OHdG level was higher in cancerous areas than in normal epithelia (P = 0.0061), whereas OGG1 expression was weaker in cancerous areas than in normal epithelia (P < 0.0001). An increase of OGG1 expression in normal epithelium was observed as 8-OHdG levels increased (P = 0.0011). However, this correlation was not observed in cancerous areas. High OGG1 expression in the cytoplasm was related to deeper tumors (P = 0.0023), node metastasis (P = 0.0065) and stage (P = 0.0019). Oxidative DNA damage, which is attributable to smoking as well as disturbances in DNA repair systems, appears to be closely related to esophageal carcinogenesis and its progression.

Abstract P2-08-04: Subtype specific chromosomal aberrations in breast cancer

Background: Breast cancer is a heterogeneous disease and divided into five distinct groups (Luminal A, Luminal B, HER2-enriched, Basal-like, and Claudin-low subtypes). DNA copy number studies have suggested that chromosomal aberrations are different among subtypes. Basal-like, and Claudin-low subtypes are mainly ER-, PR- and HER2- (triple negative: TN). Recent study reported that the basal-like subtype was the most distinct with common losses of the regions containing tumor suppressor genes such as RB1, BRCA1, INPP4B, and the greatest overall genomic instability. On the other hand, Claudin-low tumors showed few copy number changes. Luminal A tumors show fewer chromosomal copy number changes than Luminal B and HER2-enriched subtypes.

Aims: To investigate the extent of the chromosomal aberrations and to evaluate the relationships between chromosomal aberrations and breast cancer subtypes and other clinicopathological characteristics and prognosis.

Methods: Specimens were obtained from 363 invasive breast cancer patients who underwent surgery in our department between 1994 and 2011. Four breast cancer subtypes were determined by the immunohistochemical analysis of ER, PR and HER2; hormone receptor (HR; ER and/or PR)+/HER2-, HR+/HER2+, HR-/HER2+(HER2) and TN. Loss of heterozygosity (LOH) at the tumor suppressor gene (TSGs), BRCA1, BRCA2, TP53, RB1, PTEN and INPP4B, was investigated with microsatellite markers using our microsatellite analysis system. Copy number aberrations (CNAs) were analyzed by SNP-CGH array (Illumina, HumanOmni2.5-8).% Defects, which represents the percent of genome region containing chromosomal aberration, was determined by Karyostudio Software v1.4 (Illumina).

Results: The incidence of LOH at BRCA, BRCA2, TP53, RB1, PTEN and INPP4B locus was 37.4, 34.0, 57.1, 41.9, 25.8 and 18.0%, respectively. The incidence of LOH was lowest in hormone receptor (HR)+/HER2- subtype, and higher in HER2 and triple negative (TN) subtypes. LOH at INPP4B locus was significantly associated with TN subtype. The LOH at BRCA1 and TP53 loci was highest in HER2 subtype. The LOH at BRCA1, TP53 and INPP4B loci was significantly associated with poor prognosis in all cases; however, the impact of LOH at these TSGs on the prognosis was different among subtypes. Coexistence of LOH at both BRCA1 and TP53 loci was significantly associated with aggressive phenotype and chromosomal aberrations.%Defect was highest in the tumors with LOH at both BRCA1 and TP53 loci. Coexistence of LOH at both BRCA1 and TP53 loci was significantly associated with poor prognosis, especially in HR+/HER2- subtype. Many cases with TN subtype reveal gross chromosomal aberrations, and these tumors were considered to be basal-like. However, there are some cases with few chromosomal alterations in TN, whose prognosis was very poor. These tumors were considered to be Claudin-low subtype.

Conclusions: The incidence and biological significance of LOH at TSGs are different among breast cancer subtypes. Coexistence of LOH at both BRCA1 and TP53 loci was associated with gross chromosomal aberrations and poor prognosis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-08-04.

Abstract P2-06-03: The BRCA1 promoter methylation is one of the mechanisms of th BRCA1 dysfunction of triple-negative breast cancer

Background: Triple negative breast cancer (TNBC) is typically associated with aggressive tumor phenotype and poor prognosis. TNBC is also considered highly heterogeneous disease. A better understanding of molecular and histopathological features of TNBC is of great importance, in order to develop a new therapeutic strategy and to improve the prognosis of TNBC. TNBC has many similarities with basal-like breast cancer, and is also associated with BRCAness. The major role of BRCA1 is to respond to DNA damage by participating in cellular pathways for DNA repair, mRNA transcription, cell cycle regulation, and protein ubiquitination. BRCA1 function loss leads to impaired homologous recombination mediated DNA repair. A loss of BRCA1 may thus be a biomarker of responsiveness to DNA damaging agents such as PARP inhibitor and cis/carboplatin. Germline mutations in BRCA1, however, account for approximately 5% of breast cancer cases, somatic mutations in BRCA1 rarely occur. Instead, lower than normal expression of BRCA1 is reported to be an important contributing factor in sporadic tumors. The BRCA1 promoter methylation may thus play an important role in the BRCA1 function loss in sporadic breast cancer.

Aim: To evaluate the clinical importance of BRCA1 promoter methylation in breast cancer.

Materials and Methods: Specimens were obtained from 71 TNBC and 163 non-TNBC patients who underwent surgery without neoadjuvant therapy in our department between 1990 and 2011. BRCA1 promoter methylation was investigated by using combined bisulfate and restriction analysis (COBRA). The BRCA1 mRNA expression was evaluated by quantitive RT-PCR. The BRCA1 protein level was assessed by immnohistochemistry. Loss of heterozygosity(LOH) at the BRCA1 locus was analyzed with microsatellite markers (D17S855 and D17S579) using our microsatellite analysis system. Copy number variations(CNVs) were analysed by SNP-CGH array (Illumina, HumanOmni2.5-8).

Results: We found 12 patients with BRCA1 promoter methylation and all of them were TNBC (p&lt;0.0001). BRCA1 promoter methylation was associated with lymphovessel invasion (p = 0.009), high nuclear grade (p = 0.03), low BRCA1 mRNA expression (p = 0.002) and low BRCA1 protein expression (p&lt;0.0001). CNVs were observed more frequently in TNBC(p = 0.012). High CNVs significantly correlated with BRCA1 LOH (p = 0.0025), but not with BRCA1 promoter methylation among TNBC patients.

Conclusions: The BRCA1 promoter methylation is considered to be a specific feature of aggressive phenotype of TNBC and to be one of the mechanisms of BRCA1 dysfunction in breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-06-03.

Impact of disease severity on work productivity and activity impairment in Japanese patients with atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease that is characterized by chronic and persisting pruritic and eczematous lesions. There has been no study of work productivity and activity in AD patients in relation to disease severity. The purpose of this study was to examine the impact of disease severity on work productivity and activity impairment (WPAI) in adult AD patients using the Japanese version of the questionnaire. Data were collected from 112 AD patients who visited the Jikei University Hospital. Outcomes as measured by the questionnaire included employment status, total work productivity impairment (TWPI) and total activity impairment (TAI). We investigated the correlation between TWPI or TAI scores and severity scoring of AD (SCORAD) for disease severity and dermatology life quality index (DLQI) for quality of life impairment. Both TWPI and TAI scores were significantly correlated with the SCORAD and DLQI scores (P < 0.001), indicating disease severity is significantly associated with WPAI in Japanese adult AD patients. Further studies are necessary to evaluate the effects of treatments on WPAI for severe AD patients.

Esophageal replacement by colon interposition with microvascular surgery for patients with thoracic esophageal cancer: the utility of superdrainage

Replacing the thoracic esophagus with the colon is one mode of reconstruction after esophagectomy for esophageal cancer. There is, however, a high incidence of postoperative necrosis of the transposed colon. This study evaluated the outcomes of colon interposition with the routine use of superdrainage by microvascular surgery. Twenty-one patients underwent colon interposition from 2004 to 2009. The strategy for colon interposition was to: (i) use the right hemicolon; (ii) reconstruct via the subcutaneous route; (iii) perform a microvascular venous anastomosis for all patients; and (iv) perform a microvascular arterial anastomosis when the arterial blood flow was insufficient. The clinicopathologic features, surgical findings, and outcomes were investigated. The colon was used because of a previous gastrectomy in 18 patients (85.7%) and synchronous gastric cancer in three patients (14.3%). Eight patients (38.1%) underwent preoperative chemoradiotherapy including three (14.3%) treated with definitive chemoradiotherapy. Seven patients (33.3%) underwent microvascular arterial anastomosis to supplement the right colon blood supply. Pneumonia occurred in four patients (19.0%). Anastomotic leakage was observed in five patients (23.8%); however, no colon necrosis was observed. The 3-year and 5-year overall survival rates were both 50.6%. Colon interposition with superdrainage results in successful treatment outcomes. This technique is one option for colon interposition employing the right hemicolon.

Correlation between reduced p21(WAF1/CIP1) expression and abnormal p53 expression in esophageal carcinomas

p21(WAF1/CIP1) is a potent inhibitor of various cyclin-dependent kinases, the expression of which is transcriptionally regulated by tumor suppressor gene product p53. We immunohistochemically examined the expression of p53 and p21(WAF1/CIP1) in 61 esophageal squamous cell carcinomas. p53 protein was expressed in 37 (61%) of 61 carcinomas. p21(WAF1/CIP1) was consistently expressed in the normal stratified esophageal mucosa. In the carcinomas, the expression of p21(WAF1/CIP1) protein was markedly reduced or not expressed in 33 (54%) cases. Clinicopathologic analyses revealed that no significant correlation exists either between p53-positive and -negative cases or between p21(WAF1)/(CIP1)-positive and -negative cases. Twenty-four cases were p53-positive/p21(WAF1/CIP1) negative, 15 were p53-negative/p21(WAF1/CIP1)-positive, 13 were positive for both and 9 were negative for both, and these findings thus showed an inverse correlation of the positivity between p53 and p21(WAF1/CIP1) (p<0.05). Furthermore, of the 13 cases with positive staining for both, the distribution of the expression was mutually exclusive in 6 cases and coincidental in the remaining 7 cases. These findings showed the p53-dependent expression of p21(WAF1/CIP1) was observed in esophageal squamous cell carcinomas, while the lack of an absolute correlation between abnormal p53 expression and p21(WAF1/CIP1) expression suggested that the p53-independent expression of p21(WAF1/CIP1) might also occur in some portions of the esophageal squamous carcinomas, suggesting that the molecular mechanisms of esophageal carcinogenesis appear to be complicated.