JAK2(V617F) negatively regulates p53 stabilization by enhancing MDM2 via La expression in myeloproliferative neoplasms.

JAK2(V617F) is a gain of function mutation that promotes cytokine-independent growth of myeloid cells and accounts for a majority of myeloproliferative neoplasms (MPN). Mutations in p53 are rarely found in these diseases before acute leukemia transformation, but this does not rule out a role for p53 deregulation in disease progression. Using Ba/F3-EPOR cells and ex vivo cultured CD34(+) cells from MPN patients, we demonstrate that expression of JAK2(V617F) affected the p53 response to DNA damage. We show that E3 ubiquitin ligase MDM2 accumulated in these cells, due to an increased translation of MDM2 mRNA. Accumulation of the La autoantigen, which interacts with MDM2 mRNA and promotes its translation, was responsible for the increase in MDM2 protein level and the subsequent degradation of p53 after DNA damage. Downregulation of La protein or cell treatment with nutlin-3, a MDM2 antagonist, restored the p53 response to DNA damage and the cytokine-dependence of Ba/F3-EPOR-JAK2(V617F) cells. Altogether, these data indicate that the JAK2(V617F) mutation affects p53 response to DNA damage through the upregulation of La antigen and accumulation of MDM2. They also suggest that p53 functional inactivation accounts for the cytokine hypersensitivity of JAK2(V617F) MPN and might have a role in disease progression.

Evaluation of telomerase activity in non-genital Bowen's disease.

We investigated the level of telomerase activity (TA) in 17 specimens of non-genital Bowen's disease (BD) and in 14 specimens of skin without sun exposure (non-exposed skin) using a non-isotopic PCR-based telomeric repeat amplification protocol (TRAP) assay. Expression of human telomerase reverse transcriptase (hTERT; the catalytic subunit of telomerase) was also evaluated by immunochemistry in the non-genital BD tissues. Moderate to high levels of TA were detected in 41.2% of 17 non-genital BD specimens (P = 0.001). In contrast, TA was not evident in non-exposed skin. Recently, nucleolin was reported to be associated with hTERT, so we used this antibody instead of hTERT antibody. Immunohistochemistry showed that nucleolin expression was associated with high TA levels in non-genital BD. Our results also revealed differences of TA levels among non-genital BD specimens. High levels of TA in those specimens were not age related. Five out of 7 specimens (71.4%) with moderate to high TA levels were from sun-exposed sites, while the remaining 10 specimens with low levels of TA were from non-exposed sites. These results suggested that cellular DNA damage caused by ultraviolet irradiation might be associated with an increase of TA in non-genital BD. Among non-genital BD specimens, 4 out of 17 (23.5%) showed high levels of TA (median relative TA value: 79.8%; P = 0.003), which might be associated with immortalization or transformation to invasive squamous cell carcinoma.

Transient posttranslational up-regulation of telomerase activity during megakaryocytic differentiation of K562 cells.

Telomerase is active in immature somatic cells, but not in differentiated cells. However, the mechanism by which telomerase is regulated in relation to cell differentiation is not well understood. In this study, the human erythroid leukemia cell line K562 was induced to differentiate into megakaryocytes by TPA and into erythroid by STI571. The human acute myeloblastic leukemia cell line HL60 was also induced to differentiate into monocytes by TPA. Telomerase activity, the expression of human telomerase reverse transcriptase, hTERT, and the cell cycle were examined. TPA induced a transient increase in telomerase activity during the megakaryocytic differentiation while the message of hTERT decreased gradually throughout the same period. This suggests the existence of a regulatory mechanism other than transcription of hTERT. Cell cycle analysis revealed that cells in G(2)/M phase increased in number in accordance with the changes in telomerase activity. Pretreatment with PKC inhibitors inhibited the megakaryocytic differentiation, transient increase in telomerase activity, and G(2)/M arrest. These results suggest that PKC acts as a transient post-translational activator of telomerase during megakaryocytic differentiation.

Hearing ability by telephone of patients with cochlear implants.

We investigated the telephone communication ability of patients with cochlear implants who could understand conversations in natural voice without difficulty. The hearing ability of those patients with telephone adapters, which usually are used to reduce noise level in the telephone and to record into a tape recorder, was also investigated. Vowel-confusion, consonant-confusion, and speech-tracking test results of patients listening to voices by telephone and by telephone adapter were compared with those of patients listening to natural, nontelephone voices. The average score of the speech-tracking test with natural voice was 111.5 phrases per 5 minutes. This score dropped to 62.4 by telephone. However, with a telephone adapter, the score of the speech-tracking test was 109.3 phrases per 5 minutes. This was almost the same score as that of the natural voice. So, generally speaking, the telephone communication ability of cochlear implant patients was not good enough. However, hearing ability with a telephone adapter came close to hearing ability during natural speech.

Neuroleptic malignant syndrome in a parkinsonian woman during the premenstrual period.

A 45-year-old woman with Parkinson's disease developed neuroleptic malignant syndrome (NMS) despite lack of levodopa withdrawal. She experienced two episodes characterized by indomethacin-resistant hyperthermia, hyperhidrosis, and aggravation of parkinsonism. The symptoms, however, disappeared during menstruation. We suggest that the development of NMS may depend, in part, upon the hormonal state.

Alpha fetoprotein and carcinoembryonic antigen producing hepatocellular carcinoma. A case report studied by immunohistochemistry.

Hepatocellular carcinoma (HCC) showing marked elevation of serum alpha fetoprotein (AFP) (maximum; 70942.0 ng/ml at the end stage) and serum carcinoembryonic antigen (CEA)(maximum; 7368.4 ng/ml at the end stage) was surgically resected. In the resected liver, there were two different tumor nodules which were adjacent to each other but clearly separated by a thin connective tissue. One of the nodules was a well differentiated and the other was poorly differentiated HCC. Immunoperoxidase study revealed that both CEA and AFP were localized in the tumor cells of the poorly differentiated HCC. This is the first report which clearly proved CEA synthesis in the cells of HCC. Serial staining showed that there was simultaneous synthesis of CEA and AFP in some of the tumor cells.