Lack of mismatch repair enhances resistance to methylating agents for cells deficient in oxidative demethylation.

The human alkylation B (AlkB) homologs, ALKBH2 and ALKBH3, respond to methylation damage to maintain genomic integrity and cellular viability. Both ALKBH2 and ALKBH3 are direct reversal repair enzymes that remove 1-methyladenine (1meA) and 3-methylcytosine (3meC) lesions commonly generated by alkylating chemotherapeutic agents. Thus, the existence of deficiencies in ALKBH proteins can be exploited in synergy with chemotherapy. In this study, we investigated possible interactions between ALKBH2 and ALKBH3 with other proteins that could alter damage response and discovered an interaction with the mismatch repair (MMR) system. To test whether the lack of active MMR impacts ALKBH2 and/or ALKBH3 response to methylating agents, we generated cells deficient in ALKBH2, ALKBH3, or both in addition to Mlh homolog 1 (MLH1), another MMR protein. We found that MLH1koALKBH3ko cells showed enhanced resistance toward SN1- and SN2-type methylating agents, whereas MLH1koALKBH2ko cells were only resistant to SN1-type methylating agents. Concomitant loss of ALKBH2 and ALKBH3 (ALKBH2ko3ko) rendered cells sensitive to SN1- and SN2-agents, but the additional loss of MLH1 enhanced resistance to both types of damage. We also showed that ALKBH2ko3ko cells have an ATR-dependent arrest at the G2/M checkpoint, increased apoptotic signaling, and replication fork stress in response to methylation. However, these responses were not observed with the loss of functional MLH1 in MLH1koALKBH2ko3ko cells. Finally, in MLH1koALKBH2ko3ko cells, we observed elevated mutant frequency in untreated and temozolomide treated cells. These results suggest that obtaining a more accurate prognosis of chemotherapeutic outcome requires information on the functionality of ALKBH2, ALKBH3, and MLH1.

[Case of Primary Mediastinal Non-Seminomatous Germ Cell Tumor with Pathological Complete Response after Induction Chemotherapy and Residual Tumor Resection Accompanied by Late-Onset Bilateral Pneumothorax].

A man in his late teens presented to our hospital with left-sided chest pain. CT showed a 12 cm sized anterior mediastinal tumor and tiny nodules in the bilateral lower lobe of the lungs. The patient also had elevated serum AFP and hCG levels. Pathological findings of the CT-guided biopsy specimen suggested a yolk sac tumor, and no testicular abnormality was seen on ultrasound. Following whole body examination, he was diagnosed with primary mediastinal non-seminomatous germ cell tumor. After sperm cryopreservation, 4 courses of BEP(bleomycin[BLM]plus etoposide[ETP]plus cisplatin[CDDP]) chemotherapy were administered to normalize the tumor markers. The mediastinal tumor shrank but was still widely in contact with the left pulmonary artery. He underwent mediastinal tumor resection and segmentectomy of the left upper lobe via a median sternotomy. The maximum tumor size was 9 cm in diameter, and pathological examination of the specimen revealed only an immature teratoma with no malignant findings. At the same time, both the lower lung nodules were resected and pathologically identified as intrapulmonary lymph nodes. No recurrence was observed, but 6 months after surgery, he made an emergency visit to our department due to dyspnea. Bilateral pneumothorax was detected, and chest tube insertion was rapidly performed that improved with only right chest drainage. Cytology of the right hemorrhagic pleural effusion showed no evidence of malignancy. It was possible that a postoperative right-to-left shunt of the anterior mediastinum was present, leading to bilateral pneumothorax.

[A Case of Philadelphia Chromosome-Positive Acute Myeloid Leukemia Extramedullary Recurrence in a Patient Undergoing Thoracoscopy for Massive Pleural Effusion].

A man in his early 70s visited a previous hospital because of pancytopenia and was diagnosed with acute myeloid leukemia based on a bone marrowexamination. The karyotype was 46,XY, t(9;22)(q34;q11.2)[2/20], and real-time polymerase chain reaction(PCR)revealed minor bcr-abl chimeric mRNA. Finally, the patient was judged as having Philadelphia chromosome- positive acute myeloid leukemia, and remission induction chemotherapy with the JALSG AML 201 protocol was initiated in combination with dasatinib to achieve complete remission. After 3 courses of consolidation chemotherapy, the anticancer drugs were discontinued because of deterioration of his general condition and renal insufficiency. Six months after the initial treatment, he was referred to our department, and no evidence of recurrence was confirmed on bone marrow examination. However, 2 months later, right massive pleural effusion was detected, and he was admitted to the department of pneumology at our hospital. Thoracoscopic pleural biopsy was performed at the time of chest tube insertion, and he was diagnosed with acute myeloid leukemia extramedullary recurrence. Peripheral myeloblasts appeared and increased rapidly, accompanied by further exacerbation of renal function; thus, he received palliative care at the department of hematology and oncology.

Maturity-onset diabetes of the young type 5, presenting as diabetic ketoacidosis with alkalemia: A report of a case.

A 34-year-old man visited our Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, because of dry mouth and weight loss. His plasma glucose level was 32.8 mmol/L and serum levels of ketone bodies were increased, but with metabolic alkalemia. He was also suffering from renal tubular hypomagnesemia and hypokalemia. Abdominal computed tomography showed bilateral renal cysts. These findings were suggestive of maturity-onset diabetes of the young type 5. Genetic testing showed heterozygous hepatocyte nuclear factor 1 beta gene deletion. In the present case, it seemed reasonable to view hepatocyte nuclear factor 1 beta gene deletion as the common cause of maturity-onset diabetes of the young type 5-associated diabetic ketoacidosis and tubular malfunction-induced hypokalemic alkalosis. This case exemplifies the importance of hepatocyte nuclear factor 1 beta gene abnormality as a potential cause of diabetic ketoacidosis with alkalemia.

A complement C3 fragment equivalent to mammalian C3d from the common carp (Cyprinus carpio): generation in serum after activation of the alternative pathway and detection of its receptor on the lymphocyte surface.

A terminal degradation product (C3d) of mammalian complement component C3 plays an important role in modulation of the adaptive immune response through the interaction with complement receptor type 2 (CR2) on B cells. The present study is aimed at determining whether this is a functional bridge between the innate and adaptive immune systems in bony fish. The fragmentation of the complement component C3 in carp (Cyprinus carpio) serum, activated with zymosan, was analysed to ascertain if carp C3 also generates a mammalian C3d-like fragment under physiological conditions. A 35 kDa peptide reactive to the anti-carp C3 alpha-chain was detected on the zymosan particles and in the activated serum. Its N-terminal amino acid sequence identified it as carp C3d derived from the C3-H1 isoform. Another C3 isoform, C3-S, of carp was found to yield a C3d fragment at lower efficiency than C3-H1. Recombinant C3d fragments derived from C3-H1 and C3-S were produced in Escherichia coli as fusion proteins with glutathione-S-transferase (GST), and used for ligands to examine the presence of a possible CR2-like C3d receptor on carp lymphocytes. An enzyme-linked immunoadsorbent assay system, using the recombinant C3d proteins and anti-GST on a microplate to which was attached carp peripheral lymphocytes, detected a significant binding of carp C3d to the lymphocyte. The degree of binding of C3-H1-derived C3d was higher than that of C3-S-derived C3d. In addition, the binding of both ligands was inhibited by anti-C3 alpha-chain, but not by EDTA or EGTA, indicating that the putative C3d receptor does not require divalent cation. These properties agree well with those reported for mammalian CR2.