The PDZ domain binding motif (PBM) of human T-cell leukemia virus type 1 Tax can be substituted by heterologous PBMs from viral oncoproteins during T-cell transformation.

Several tumor viruses, such as human T-cell leukemia virus (HTLV), human papilloma virus (HPV), human adenovirus, have high-oncogenic and low-oncogenic subtypes, and such subtype-specific oncogenesis is associated with the PDZ-domain binding motif (PBM) in their transforming proteins. HTLV-1, the causative agent of adult T-cell leukemia, encodes Tax1 with PBM as a transforming protein. The Tax1 PBM was substituted with those from other oncoviruses, and the transforming activity was examined. Tax1 mutants with PBM from either HPV-16 E6 or adenovirus type 9 E4ORF1 are fully active in the transformation of a mouse T-cell line from interleukin-2-dependent growth into independent growth. Interestingly, one such Tax1 PBM mutant had an extra amino acid insertion derived from E6 between PBM and the rest of Tax1, thus suggesting that the amino acid sequences of the peptides between PBM and the rest of Tax1 and the numbers only slightly affect the function of PBM in the transformation. Tax1 and Tax1 PBM mutants interacted with tumor suppressors Dlg1 and Scribble with PDZ-domains. Unlike E6, Tax1 PBM mutants as well as Tax1 did not or minimally induced the degradations of Dlg1 and Scribble, but instead induced their subcellular translocation from the detergent-soluble fraction into the insoluble fraction, thus suggesting that the inactivation mechanism of these tumor suppressor proteins is distinct. The present results suggest that PBMs of high-risk oncoviruses have a common function(s) required for these three tumor viruses to transform cells, which is likely associated with the subtype-specific oncogenesis of these tumor viruses.

Alpha-fetoprotein-producing adenocarcinoma in which the metastatic route was determined from calcified lesions.

Alpha-fetoprotein (AFP)-producing adenocarcinoma is known for its rapid progression and poor prognosis, and chemotherapy regimens are yet to be standardized. Here we describe the first report of AFP-producing adenocarcinoma with calcification. The metastatic route was visualized from the calcification, and combination chemotherapy was performed. A 77-year-old Japanese man was transferred to our hospital for treatment of liver tumors. Computed tomography (CT) revealed multiple liver tumors with portal vein tumor thrombosis. The tumors were highly attenuated before enhancement, suggesting various degrees of calcification. Serum levels of carcinoembryonic antigen (CEA), AFP, and the proportion of fucosylated AFP were considerably elevated. Gastroduodenoscopy revealed an elevated tumor occupying the duodenal bulb with an ulcerative lesion in the vicinity of the gastroduodenal junction, and biopsy specimens from the duodenum and liver revealed medullary adenocarcinoma with calcification. Three-dimensional reconstruction of CT images clearly showed that the calcified lesions had spread from the gastroduodenal junction to the liver via a route comprising the corresponding local vein, the superior mesenteric vein, and portal vein. The patient was accordingly diagnosed with calcified AFP-producing adenocarcinoma with multiple liver metastases. Combination chemotherapy using TS-1 and cisplatin (CDDP) resulted in a striking response for the initial 4 months in terms of tumor markers and CT findings. This is the first report of AFP-producing adenocarcinoma with calcification. A metastatic route from the primary tumor to the liver was clearly visualized by tracing the calcified lesions. Combination chemotherapy based on 5-fluorouracil and CDDP may have the potential to prolong survival.

Decompensated lamivudine-resistant hepatitis B virus-related cirrhosis treated successfully with adefovir dipivoxil allowing surgery for hepatocellular carcinoma.

We describe a 64-year-old man with decompensated hepatitis B virus (HBV)-related cirrhosis who became resistant to lamivudine. He was started on adefovir at 10 mg daily while continuing lamivudine therapy. Several months later, his liver function improved and subsequently his ascites disappeared. The serum HBV-DNA level became undetectable 11 months later. Twenty months after the start of additional treatment with adefovir, one hepatocellular carcinoma (HCC) was detected, and the patient underwent a successful hepatectomy. Our findings suggest that the addition of adefovir to ongoing lamivudine therapy is useful for improving liver function in patients with decompensated lamivudine-resistant HBV-related cirrhosis, allowing surgery for HCC.