Yasuhiro Arakawa

Both NUP98/TOP1 and TOP1/NUP98 transcripts are detected in a de novo AML with t(11;20)(p15;q11).

The NUP98 gene is involved in several chromosomal abnormalities associated with acute leukemia. The recurrent t(11;20)(p15;q11) chromosomal translocation results in generation of the NUP98/TOP1 chimeric gene. This abnormality has been observed primarily in therapy‐related leukemias, and TOP1/NUP98 transcripts have not been demonstrated. We describe a case of de novo acute myeloid leukemia with t(11;20)(p15;q11), with no known history of exposure to chemicals. The translocation occurred in intron 13 of NUP98 and intron 7 of TOP1, as in the three previously reported cases. The breakpoint in NUP98 was exactly the same as that found in a previously reported case. In addition, a reciprocal TOP1/NUP98 transcript was detected for the first time in our patient.

Simultaneous treatment with camptothecin and valproic acid suppresses induction of Bcl-XL and promotes apoptosis of MCF-7 breast cancer cells

Camptothecin derivatives have been widely used for chemotherapy in patients with various cancers, but intrinsic and acquired drug resistance is major drawback to be overcome. In the present study, we demonstrated that simultaneous treatment with camptothecin and valproic acid induced apoptosis of MCF-7 cells, whereas neither agent alone could efficiently induce apoptosis. This induction of apoptosis was associated with loss of the mitochondrial membrane potential and was caspase dependent. Further investigation showed that concurrent treatment modulated the expression of pro-apoptotic and anti-apoptotic genes. Bcl-XL expression was induced in MCF-7 cells treated with camptothecin alone, but not in cells treated simultaneously with camptothecin and valproic acid. Ectopic overexpression of Bcl-XL in MCF-7 cells completely suppressed the induction of apoptosis, even with simultaneous treatment. On the other hand, efficient induction of apoptosis was achieved by treatment with camptothecin and Bcl-XL inactivation (using siRNA or BH3 mimetic). The cytotoxic effect of camptothecin combined with valproic acid was more than additive for MCF-7 cells. Taken together, our results suggest that simultaneous administration of camptothecin and valproic acid might be useful for anticancer therapy.

Novel missense mutation of the DNA topoisomerase I gene in SN-38-resistant DLD-1 cells.

Irinotecan hydrochloride, a camptothecin derivative, is one of the most effective drugs for colorectal cancer, and SN-38 is its main active metabolite. Development of resistance is a major obstacle to the clinical application of this drug. We established an SN-38-resistant subline from DLD-1 human colon cancer cells by continuous exposure to SN-38 and studied the mechanisms of resistance. The resistant subline (designated as DLDSNR6) had 10- to 100-fold higher resistance to camptothecin derivatives but showed no cross-resistance to doxorubicin, mitomycin C, and etoposide. DLDSNR6 cells carried a missense mutation in one allele of the DNA topoisomerase I gene that substituted glycine for serine at amino acid residue 365 accompanied by loss of the latter part of the remaining wild-type allele. Topoisomerase I expression was equal in DLDSNR6 and DLD-1 cells, but the nuclear extract of DLDSNR6 cells showed lower topoisomerase I catalytic activity. Moreover, exposure to camptothecin caused less accumulation of topoisomerase I-DNA complexes in DLDSNR6 cells than in DLD-1 cells. These findings suggest that the mutation interfered with both the catalytic activity of topoisomerase I and the stability of the ternary complex between topoisomerase I, DNA, and SN-38. This SN-38-resistant DLDSNR6 cell line may be useful for understanding the mechanisms of topoisomerase I function and drug-enzyme interactions. [Mol Cancer Ther 2006;5(3):502–8]

Three missense mutations of DNA topoisomerase I in highly camptothecin-resistant colon cancer cell sublines

Various anticancer drugs, including camptothecins and indolocarbazoles, target DNA topoisomerase I (Top1). We previously described the camptothecin-resistant colon cancer cell line DLDSNR6, which has a Gly365Ser missense mutation in Top1. In the present study, we established highly camptothecin-resistant sublines from DLDSNR6 cells by continuous exposure to higher camptothecin concentrations. The established sublines grew in the presence of 30 μM of camptothecin, but exhibited markedly retarded growth. In addition to Gly365Ser, these sublines harbored a Top1 Gly717Arg mutation and some had also a Top1 Gln421Arg mutation. Top1 activity was reduced to approximately one-eighth in highly resistant cell lines compared with that in parental DLD-1 cells. Resistant clones with 3 Top1 mutations including Gln421RArg exhibited the highest resistance to the indolocarbazole J-107088 in terms of the effect on the cell cycle distribution. The Gln421 mutation was equivalent to a mutation recently found in camptothecin biosynthesizing plants, but it has not previously been found in mammalian cells.

Antimyeloma activity of bromodomain inhibitors on the human myeloma cell line U266 by downregulation of MYCL.

Bromodomain and extraterminal protein (BET) inhibitors suppress the expression of c-MYC. U266, a human myeloma cell line, expresses the MYCL gene, but not the c-MYC gene. Our aim was to analyse the antimyeloma activity of BET inhibitors on U266 cells. Two BET inhibitors, I-BET151 and JQ1, were tested. U266 cell proliferation decreased to 61.5 and 54.0% of the control after incubation with 500 nmol/l I-BET151 for 72 and 96 h and to 53.5 and 56.4% of control after incubation with 500 nmol/l JQ1 for 72 and 96 h by MTS tetrazolium, respectively. BET inhibitors induced cell cycle arrest at the G1 phase in U266 cells, but did not induce apoptosis by flow cytometry. According to Gene Set Enrichment Analysis, MYC-related genes were significantly downregulated in U266 cells treated with I-BET151 similar to KMS11 cells that expressed c-MYC. The MYCL1 was expressed in U266 cells, whereas c-MYC and MYCN were not by quantitative real-time reverse-transcription-PCR. Incubation with I-BET151 induced downregulation of MYCL1 in U266 cells. BET inhibitors decreased the cell proliferation in U266 cells with overexpression of MYCL less than those without overexpression of MYCL. BET inhibitors induce G1 arrest without apoptosis and interfere with the proliferation of U266 myeloma cells, which express MYCL, but not c-MYC. BET inhibitors might be active in cancers that express MYCL, but not c-MYC.

Significant response to ramucirumab monotherapy in chemotherapy‑resistant recurrent alpha‑fetoprotein‑producing gastric cancer: A case report

Alpha-fetoprotein (AFP)-producing gastric cancer (AFPGC) is a relatively rare type of gastric cancer characterized by a high incidence of liver and lymph node metastases, and a poor prognosis. Few advanced AFPGC cases treated successfully with conventional chemotherapy have been reported thus far. Although the development of molecular-targeted therapy has improved the prognosis of various types of cancer, there are currently no tailored therapies for AFPGC. In the present report, the case of a chemotherapy-resistant recurrent AFPGC patient who exhibited a significant response to ramucirumab monotherapy is presented. Following six doses of ramucirumab, a metastatic lymph node displayed central necrosis, and the patients serum AFP levels decreased from 12,800 to 225 ng/ml. AFPGC is known to have increased vascular endothelial growth factor (VEGF) expression and rich neovascularization. Furthermore, in the present case, tumor cells were positive for VEGF. Ramucirumab is a monoclonal antibody for VEGF receptor-2 and the first anti-angiogenic drug approved for the treatment of advanced gastric cancer. However, the clinical efficacy of ramucirumab in patients with AFPGC has not been reported previously. The present report suggests that AFP production in gastric cancer can be a predictor for the response to anti-angiogenic drugs such as ramucirumab.

Early measurement of urinary N-acetyl-β-glucosaminidase helps predict severe hyponatremia associated with cisplatin-containing chemotherapy

BACKGROUND Although cisplatin is a widely used anticancer drug for treating various types of cancer, its clinical application is limited by severe systemic toxicities, such as nephropathy, hematologic toxicity, and gastrointestinal toxicity. There are no reliable and validated biomarkers to predict adverse events caused by cisplatin. METHODS Sixty-six patients who underwent cisplatin-containing first-line chemotherapy between June 2010 and November 2013 were retrospectively analyzed. Data on urinary N-acetyl-β-glucosaminidase activities measured 24-48 h after cisplatin infusion were retrieved, and adverse events during the first course of chemotherapy were recorded according to the Common Terminology Criteria for Adverse Events version 4.0. RESULTS Patient characteristics were: male/female 60/6, median age 65 (range 36-78) years, esophageal/gastric/other cancer 60/4/2, chemotherapy regimen docetaxel-cisplatin-fluorouracil/fluorouracil-cisplatin/S-1-cisplatin 54/8/4, cisplatin dose (mg/sm) 60/70/80 16/43/7. Grade 3/4 adverse events were leukopenia (40.9%), neutropenia (54.4%), febrile neutropenia (37.9%), hyponatremia (28.8%), and acute kidney injury (37.9%). Patients with 20 units/gram creatinine or higher urinary N-acetyl-β-glucosaminidase developed statistically lower minimum serum sodium concentration (median 126 vs. 134 mEq/L, p = 0.0053). There were no significant correlations between urinary N-acetyl-β-glucosaminidase and the development of other severe adverse events. CONCLUSION Early significant increase in urinary N-acetyl-β-glucosaminidase predicts subsequent development of severe hyponatremia after cisplatin-containing chemotherapy.

Complete response of esophageal small cell carcinoma amrubicin treatment

Small cell carcinoma of the esophagus (SmCCE) is a rare and aggressive disease known to have a poor prognosis. SmCCE patients are generally treated with a chemotherapeutic regimen for small cell lung cancer. Salvage therapy for patients with relapsed or refractory tumors has not yet been established. A 63-year-old man with extensive SmCCE was treated with chemotherapy consisting of cisplatin (CDDP) and irinotecan (CPT-11). After the second course of CPT-11/CDDP, the celiac lymph node increased in size. Amrubicin (AMR) as second-line chemotherapy was started. The patient had a complete response after the fifth course of AMR, resulting in an 8-month progression-free survival after initial administration. This case suggests that, as in small cell lung cancer, AMR is effective for SmCCE.

Chemotherapy for alpha-fetoprotein producing gastric cancers expressing human epidermal growth factor receptor 2

Although, gastric cancer is one of the most common cancers worldwide, alpha-fetoprotein (AFP) producing human epidermal growth factor receptor 2 (HER2) positive gastric cancers are rare. AFP producing gastric cancer has a poor prognosis and an appropriate treatment option has not been established to date. A 75-year-old woman with AFP- producing gastric cancer was treated with S-1, an oral fluoropyrimidine derivative, chemotherapy after distal gastrectomy. Recurrence of gastric cancer was observed after 18 months and immunohistochemistry analysis showed AFP and HER2 positive gastric cancer. The patient received combination therapy containing capecitabine, cisplatin, and trastuzumab. Computed tomography scans showed regression of the lymph node metastasis. The patients quality of life substantially improved after the treatment. Thus, the present case suggests that AFP and HER2 positive gastric cancer can be effectively treated with, capecitabine, cisplatin, and trastuzumab combination therapy.