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Human T-cell leukemia virus type 1 (HTLV-1) Tax affects cellular genomic stability and senescence. As yet, the mechanism(s) for these events caused by Tax is incompletely understood. Here, we show that Tax expression in primary human cells induces reactive oxygen species (ROS), which elicits DNA damage and the expression of senescence marker. Treatment with a ROS scavenger or knockdown of Tax expression by small interfering RNA (siRNA) abrogated Tax-induced DNA damage and the expression of senescence marker. Our data suggest that ROS induction explains Tax-induced cellular DNA damage and cellular senescence.

Mieap, a novel p53-inducible protein, plays a key role in maintaining healthy mitochondria in various pathophysiological states. Here, we show that Mieap deficiency in ApcMin/+ mice is strikingly associated with the malignant progression of murine intestinal tumors. To understand the role that Mieap plays in in vivo tumorigenesis, we generated Mieap heterozygous (ApcMin/+ Mieap+/−) and homozygous (ApcMin/+ Mieap−/−) ApcMin/+ mice. Interestingly, the ApcMin/+ mice with the Mieap+/− and Mieap−/− genetic background revealed remarkable shortening of the lifetime compared to ApcMin/+ mice because of severe anemia. A substantial increase in the number and size of intestinal polyps was associated with Mieap gene deficiency. Histopathologically, intestinal tumors in the Mieap-deficient ApcMin/+ mice clearly demonstrated advanced grades of adenomas and adenocarcinomas. We demonstrated that the significant increase in morphologically unhealthy mitochondria and trace accumulations of reactive oxygen species may be mechanisms underlying the increased malignant progression of the intestinal tumors of Mieap-deficient ApcMin/+ mice. These findings suggest that the Mieap-regulated mitochondrial quality control plays a critical role in preventing mouse intestinal tumorigenesis.

It was considered that the extremely high Langerhans cell infiltration in the tumours was caused by HPV infection. The extremely large number of Langerhans cells in the tumours contributes to the favourable prognosis for HPV-infected lung cancer.

BACKGROUND Thymic carcinomas are rare neoplasms, and information regarding the results of treatment and possible prognostic factors in patients with these tumors is limited. METHODS The records of 40 patients with histologically confirmed thymic carcinoma who were treated between 1984 and 1998 were reviewed. Twenty‐seven patients were treated with surgical resection followed by radiotherapy with or without chemotherapy, and the remaining 13 patients were treated with radiotherapy with or without chemotherapy. The median follow‐up time for the 13 surviving patients was 87 months (range, 44–193 months). RESULTS The 5‐year and 10‐year actuarial overall survival rates in all patients were 38% and 28%, respectively. On univariate analysis, complete resection, Karnofsky performance status (KPS), histology, and Masaoka stage at the time of diagnosis were found to have a significant impact on overall survival, whereas on multivariate analysis, complete resection, KPS, and histology were found to be significant prognostic factors. With regard to the degree of resection, 12 of 16 patients (75%) treated with complete resection were alive and free of disease at the time of last follow‐up whereas 1 of 24 patients (4%) treated with incomplete resection or biopsy still was alive. Among 12 surviving patients treated with complete resection, 8 with resectable tumors at the time of presentation all had low‐grade histology (squamous cell carcinoma) and were treated successfully with complete resection and postoperative radiotherapy with or without adjuvant chemotherapy. The remaining four patients with unresectable tumors at the time of presentation were treated successfully with neoadjuvant chemotherapy, complete resection, and postoperative radiotherapy. CONCLUSIONS The results of the current study indicate that multimodal treatment, especially complete resection and postoperative radiotherapy with or without chemotherapy, is a curative therapy for thymic carcinomas. Cancer 2002;94:3115–9. © 2002 American Cancer Society. DOI 10.1002/cncr.10588

Background: Squamous differentiation/squamous metaplasia is often associated with endometrial adenocarcinoma and benign lesions, such as endometrial hyperplasia and chronic endometritis. Morules have distinct histological characteristics, and are referred to as squamous metaplasia or squamoid metaplasia. Aim: To focus on the histological characteristics of morules and clarify the difference between morules and squamous differentiation. Materials/Methods: Twenty endometrioid carcinomas with morules or squamous differentiation, five adenosquamous carcinomas, and eight non-carcinomatous endometrial lesions with morules were investigated. Numerous antibodies for epithelial membrane antigen (EMA), involucrin, cytokeratins, neuropeptides, and oncofetal antigens were used for immunohistochemistry. In situ hybridisation and polymerase chain reaction were used to detect human papillomavirus (HPV). Results: The morules observed were uniform cell clusters, with no squamous differentiation. They were immunonegative for epithelial antigens including involucrin, EMA, and cytokeratins, but were positive for neurone specific enolase. A few morules were immunopositive for acetylcholine esterase, and one case was positive for somatostatin; neither oncofetal nor proliferative cell markers, including blood group A, B, and AB, or other neuropeptides were demonstrated in the morules. HPV DNA was not found in either the morules in the carcinomas or in the benign lesions. However, true squamous differentiation tissue in four endometrioid carcinomas and two adenosquamous carcinomas was HPV positive using in situ hybridisation. Conclusion: Morules are histologically distinct from squamous metaplasia/squamous differentiation tissue. Morules are thought to be neuroectodermal-like cell clusters, and are not infected with HPV. In contrast, some of the true squamous differentiation tissue was associated with HPV infection.

Aim: In Okinawa, a subtropical island located between the East China Sea and Pacific Ocean, 2000 km south of mainland Japan, the incidence of oral squamous cell carcinoma is 1.5 times higher than that seen in mainland Japan, and a large number of these patients have been reported to be infected with the Epstein-Barr virus (EBV). This study aimed to gain a better understanding of the pathogenesis of this malignancy in this area by carrying out genomic analysis of EBV. Methods: Fifty four patients with oral squamous cell carcinoma reported from 1997 to 1999 in Okinawa were compared with 21 and 20 patients from Kitakyushu and Kumamoto in Kyushu, mainland Japan, respectively. Diagnosis was confirmed by conventional histological examination of paraffin wax sections. EBV was detected by non-isotopic in situ hybridisation (NISH) and the polymerase chain reaction (PCR) (Bam HI-F, EBV nuclear antigen 2 (EBNA2), and latent membrane protein 1 (LMP-1) regions). Sequence analysis of the PCR products was also carried out. Results: In Okinawa, 25 patients were found to be infected with EBV type A by analysing the 3′ sequence divergence of the EBNA2 genes. Six patients were positive for EBV type B, and eight for both type A and B. Therefore, type A virus infection was demonstrated in 33 of 54 patients, and type B in 14 of 54. In total, 39 of 54 patients were infected with EBV. However, the "f" variant was shown in only one patient, who was also infected with type A virus. In contrast, 97.0% of EBV type A infected patients showed a 30 bp deletion of the LMP-1 gene, but those infected with EBV type B did not. Sequence analysis of the type A virus EBNA2 gene revealed slight variations of the sequence (mutations)-48991 G→T and 48998 C→A-in 18 of 33 cases compared with the B95-8 strain, and in 14 cases, in addition to these, a further mutation of 48917 T→C was demonstrated; in the single remaining case, only one mutation at 49137 A→G was detected. The mutations at 48991 (G→T), and 49137 (A→G) are associated with amino acid changes Arg→Met and Thr→Ala, respectively. In contrast, no mutation was seen in the EBNA2 DNA from the 14 cases of type B virus when compared with that of the Jijoye strain. In Kitakyushu and Kumamoto, only 10 of 41 patients (six in Kitakyushu and four in Kumamoto) were infected with EBV. Among them, nine patients were infected with type A virus, and only one patient from Kitakyushu was infected with type B virus. The 48991 G→T and 48998 C→A mutations of the EBNA2 region were demonstrated in type A virus, but the 48917 T→C and 49137 A→G mutations were not when compared with the B95-8 strain. In the case of type B virus no mutation was noted. A 30 bp deletion was found in these nine cases of type A, but not in type B. The sequence analysis of EBV type A in Okinawa, Kitakyushu, and Kumamoto showed slight variations when compared with B95-8, but EBV type B LMP-1 did not when compared with the Jijoye strains. Conclusion: In Okinawa, EBV infection was frequently demonstrated in oral squamous cell carcinoma (p < 0.001)....

Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus etiologically causal of adult T-cell leukemia (ATL). The virus encodes a Tax oncoprotein that functions in transcriptional regulation, cell cycle control, and transformation. ATL is a highly virulent cancer that is resistant to chemotherapeutic treatments. To understand this disease better, it is important to comprehend how HTLV-1 promotes cellular growth and survival. Tax activation of NF-B is important for the proliferation and transformation of virus-infected cells. We show here that prolyl isomerase Pin1 is over expressed in HTLV-1 cell lines; Pin1 binds Tax and regulates Tax-induced NF-B activation.