Immunohistochemical study of p53 overexpression in radiation-induced colon cancers

p53 Expression as a Diagnostic Biomarker in Ulcerative Colitis-Associated Cancer

Ulcerative colitis (UC) is defined as an idiopathic inflammatory disorder primarily involving the mucosa and submucosa of the colon. UC-associated colon cancers (also known as colitic cancers) develop through the inflammation-dysplasia sequence, which is a major problem affecting the prognosis of patients with UC. It is therefore very important to detect malignancy from UC at an early stage. As precancerous lesions arising in UC, there are pathological adenomatous changes, basal cell changes, in situ anaplasia, clear cell changes, and pan-cellular change. It is considered that the mutation of the p53 gene plays a crucial role, and the protein expression of p53 in dysplastic crypts may serve as a good biomarker in the early stages of UC-associated colon carcinogenesis. Immunohistochemistry for p53 is a very valuable diagnostic tool in UC-associated colon cancers. However, protein expression of p53 is not always universal, and additional methods may be required to assess p53 status in UC-associated colon cancers.

Radiation-associated colon cancer: A case report

Radiation-associated colon cancer is a rare clinical entity. We herein describe the case of a patient with radiation-associated colon cancer who had undergone low anterior resection for rectal cancer following preoperative radiotherapy. Certain characteristics of radiation-associated colon cancer are highlighted. The patient was a 48-year-old man who had undergone low anterior resection for rectal cancer following preoperative radiotherapy at a total dose of 50 Gy, at the age of 29 years. When the patient presented at the University of Tokyo Hospital, 19 years after the surgery, he complained of severe anal pain and frequent defecation. Colonoscopy revealed two flat tumors in the sigmoid colon, located 10 cm to the oral side of the anastomosis site, which were diagnosed as well-differentiated adenocarcinomas. In addition, colonoscopy identified five flat polyps near the tumors, which were resected endoscopically. Computed tomography and magnetic resonance imaging revealed a mass in the sigmoid colon and no evidence of distant metastasis. Laparoscopic-assisted intersphincteric resection of the rectum and sigmoid colon with diverting ileostomy was performed. There were no specific postoperative complications and the patient was discharged from the hospital on the 20th postoperative day. On pathological examination, the resected rectum and sigmoid colon contained two separate tumors and six flat polyps. The two tumors were diagnosed as well-differentiated adenocarcinomas with invasion of the subserosa and submucosa, respectively. A total of 17 regional lymph nodes without metastasis were resected. The six flat polyps were diagnosed as tubular adenomas. We herein present a case of a radiation-associated colon cancer in a patient who had undergone low anterior resection for rectal cancer following preoperative radiotherapy 19 years prior. Colonoscopic surveillance of radiation-associated colon cancer may be indicated for rectal cancer patients treated with preoperative radiotherapy, particularly for those with long-standing radiation-induced colitis.

Insight into mucinous colorectal carcinoma: clues from etiology

The prognostic impact of mucinous carcinoma (MC) in colorectal cancer (CRC) has been subject to debate ever since the introduction of the classification of tumors according to their histological differentiation. MC is a distinct clinical and pathological entity within the spectrum of CRC and accounts for approximately 10-15 % of cases. Factors involved in MC development have not been completely understood, but clinical observations may lead to a better insight into the etiology of MC. In this article, we provide an in-depth review of the literature regarding etiological aspects of MC. We show that there are worldwide differences in the prevalence of MC, with low rates in Asian countries and higher rates in the western world. Moreover, MC is more commonly diagnosed in patients suffering from inflammatory bowel diseases or Lynch syndrome and an increased rate of MC is observed in patients with radiotherapy-induced CRCs. These findings are suggestive of a different oncogenic development. Identification of conditions that are associated with MC generates insight into the etiological pathways leading to the development of this special subtype.

Sigmoidectomy for radiation-induced sigmoid colonic dysplasia 35 years after radiotherapy for cervical cancer

Although radiation-induced colonic cancer is thought to arise from dysplasia, no guidelines exist for the treatment of such dysplasia. Therefore, clinicians must make treatment decisions for this condition on a case-by-case basis. Especially when the operative procedure is being decided, it is necessary to consider postoperative quality of life for advanced age. We report a patient who underwent sigmoidectomy for sigmoid colonic dysplasia that developed 35 years after radiation therapy. A 73-year-old woman who had undergone total hysterectomy and chemoradiotherapy for cervical cancer 35 years previously presented following a positive fecal occult blood test. Colonoscopy revealed sigmoid colonic dysplasia. To ensure reliable removal of the lesion, we elected to perform surgical resection. Given the patient's age, we performed sigmoidectomy rather than resecting the entire irradiated intestinal tract. The diagnosis of dysplasia was confirmed based on pathological findings, which included duct proliferation with partial structural atypia.

Recent advances in the management of radiation colitis

Radiation colitis, an insidious, progressive disease of increasing frequency, develops 6 mo to 5 years after regional radiotherapy for malignancy, owing to the deleterious effects of the latter on the colon and the small intestine. When dealing with radiation colitis and its complications, the most conservative modality should be employed because the areas of intestinal injury do not tend to heal. Acute radiation colitis is mostly self-limited, and usually, only supportive management is required. Chronic radiation colitis, a poorly predictable progressive disease, is considered as a precancerous lesion; radiation-associated malignancy has a tendency to be diagnosed at an advanced stage and to bear a dismal prognosis. Therefore, management of chronic radiation colitis remains a major challenge owing to the progressive evolution of the disease, including development of fibrosis, endarteritis, edema, fragility, perforation, partial obstruction, and cancer. Patients are commonly managed conservatively. Surgical intervention is difficult to perform because of the extension of fibrosis and alterations in the gut and mesentery, and should be reserved for intestinal obstruction, perforation, fistulas, and severe bleeding. Owing to the difficulty in managing the complications of acute and chronic radiation colitis, particular attention should be focused onto the prevention strategies. Uncovering the fibrosis mechanisms and the molecular events underlying radiation bowel disease could lead to the introduction of new therapeutic and/or preventive approaches. A variety of novel, mostly experimental, agents have been used mainly as a prophylaxis, and improvements have been made in radiotherapy delivery, including techniques to reduce the amount of exposed intestine in the radiation field, as a critical strategy for prevention.

Effects of radiation damage on intestinal morphology

The current flow of papers on intestinal structure, radiation science, and intestinal radiation response is reflected in the contents of this review. Multiparameter findings and changes in compartments, cells, or subcellular structure all contribute to the overall profile of the response. The well-recognized changes in proliferation, vessels, and fibrogenesis are accompanied by alterations in other compartments, such as neuroendocrine or immune components of the intestinal wall. The responses at the molecular level, such as in levels of hormones, cytokines, or neurotransmitters, are of fundamental importance. The intestine responds to localized radiation, or to changes in other organs that influence its structure or function: some structural parameters respond differently to different radiation schedules. Apart from radiation conditions, factors affecting the outcome include the pathophysiology of the irradiated subject and accompanying treatment or intervention. More progress in understanding the overall responses is expected in the next few years.

Mechanism of exogenous nucleic acids and their precursors improving the repair of intestinal epithelium after gamma-irradiation in mice

AIM:To clone expressed genes associated with repair of irradiation-damaged mice intestinal gland cells treated by small intestinal RNA, and to explore the molecular mechanism of exogenous nucleic acids improving repair of intestinal crypt.METHODS:The animal mode of test group and control group was established, forty-five mice being irradiated by gamma ray were treated with small intestinal RNA as test group, forty mice being irradiated by gamma ray were treated with physiological saline as control group,five mice without irradiation were used as normal control, their jejunal specimens were collected respectively at 6h, 12h,24h, 4d and 8d after irradiation. Then by using LD-PCR based on subtractive hybridization, these gene fragments differentially expressed between test group and control group were obtained, and then were cloned into T vectors as well as being sequenced. Obtained sequences were screened against. GeneBank, if being new sequences, they were submitted to GeneBank.RESULTS:Ninety clones were associated with repair of irradiation-damaged intestinal gland cells treated by intestinal RNA. These clones from test group of 6h, 12h, 24h, 4d and 8d were respectively 18, 22, 25, 13, 12. By screening against GeneBank, 18 of which were new sequences, the others were dramatically similar to the known sequences, mainly similar to hsp, Nmi,Dutt1, alkaline phosphatase, homeobox, anti-CEA ScFv antibody, arginine/serine kinase and BMP-4,repA. Eighteen gene fragments were new sequences,their accept numbers in GeneBank were respectively AF240164-AF240181.CONCLUSION:Ninety clones were obtained to be associated with repair of irradiation damaged mice intestinal gland cells treated by small intestinal RNA, which may be related to abnormal expression of genes and matched proteins of hsp, Nmi, Dutt1, Na, K-ATPase,alkalineph-osphatase, glkA, single stranded replicative centromeric gene as well as 18 new sequences.

Expression of ICAM-1 and acute inflammatory cell infiltration in the early phase of radiation colitis in rats

Inflammatory cell infiltration of the colon is observed at an early stage of radiation-induced colitis. The emigration of inflammatory cells from the circulation requires interactions between cell adhesion molecules on the vascular endothelium and molecules on the surface of leukocytes. To elucidate this process, the present work analyzes the kinetics of the expression of intercellular adhesion molecule-1 (ICAM-1) and the accumulation of inflammatory myeloperoxidase (MPO)-positive cells in relation to the appearance of acute radiation colitis prior to an overt radiation-induced ulcer. Colon tissues were obtained from Wistar Kyoto rats at various times after 22.5 Gy irradiation to the rectum. Histologically, crypt depletion and numerous inflammatory cells were observed 4 days after irradiation, and mucosal ulcer 6 days after irradiation. ICAM-1 immunopositivity was present in the endothelial cells of small vessels in the mucosa of both control and irradiated rats. ICAM-1 mRNA expression was detected in normal colon and irradiated colon by reverse transcription-PCR. In Northern blotting, ICAM-1 mRNA levels were found to increase markedly in the irradiated colon compared to the normal colon. In Western blotting. ICAM-1 protein expression also increased with a peak one day after irradiation, and remained elevated up to 6 days thereafter. The number of MPO-positive cells in lamina propria mucosa increased in a time-dependent fashion from 6 h to 6 days after irradiation. These data suggest that up-regulation of ICAM-1 in endothelial cells and accumulation of MPO positive cells play important roles in the development of radiation-induced colonic ulcer.

Detection of chromatin-bound PCNA in mammalian cells and its use to study DNA excision repair

Compelling evidence indicates that proliferating cell nuclear antigen (PCNA) is an indispensable factor not only in DNA replication but in nucleotide excision repair (NER), alternative pathway of base excision repair (BER), and mismatch repair. The common function of PCNA in each of these is to assist in the initiation of DNA synthesis by providing a scaffolding clamp as a trimer catalyzed by RF-C at the 3'-OH terminus of a nascent DNA strand, to which DNA polymerase delta or epsilon can bind. Interestingly, DNA synthesis is reported to be ingeniously inhibited in replication, but not in NER owing to the interaction with CDKN1A (formerly known as p21/WAF1/CIP1). Furthermore, several proteins, XPG, FEN1, and DNA ligase I, recently were shown to competitively bind to the same region of PCNA, the interdomain connector loop, to which DNA polymerase delta or epsilon also binds. PCNA therefore seems to have a regulatory role in these DNA transactions. The in vitro reconstituted experimental system has been a powerful tool to obtain these lines of evidence, but another approach, immunofluorescence studies, also has been a contributor. In fact, the involvement of PCNA in DNA replication, NER, and BER has for the first time been indicated by a unique method that makes visible only in vivo chromatin-bound PCNA. The usefulness of this method and the importance of cooperative studies done with in vitro and in vivo experimental systems is discussed in terms of DNA excision repair.