Mitsuhiro Suenaga

Histone deacetylase inhibitors suppress telomerase reverse transcriptase mRNA expression in prostate cancer cells.

Telomerase activity is involved in cellular immortality. We have recently demonstrated that telomerase activity is closely associated with cell proliferation in prostate cancers. Telomerase is composed primarily of the catalytic subunit (hTERT) and the RNA template (hTERC), and hTERT expression is regulated by several factors such as c‐MYC and p21Waf1. Histone deacetylase (HDAC) inhibitors are known to modulate transcription and exhibit antiproliferative effects on cancer cells. The present study was designed to evaluate the effects of HDAC inhibitors on hTERT mRNA expression in prostate cancer cells. LNCaP and PC‐3 cells were treated with HDAC inhibitors, trichostatin A (TSA) and sodium butyrate (NaB); mRNA expression and telomerase activity were evaluated by RT‐PCR and the TRAP assay, respectively. In LNCaP cells, hTERT mRNA expression was suppressed at 1 and 3 hr after treatment with 1 μM TSA and 4 mM NaB, respectively, followed by inhibition of telomerase activity. The inhibition of hTERT mRNA expression preceded suppression of cell proliferation. In PC‐3 cells, TSA and NaB also inhibited cell proliferation, hTERT mRNA expression and telomerase activity. In both cell lines, TSA and NaB had no effect on hTERC expression, or on expression of c‐myc and p21Waf1 mRNA. These effects of TSA and NaB were unlikely to be consequences of cell cycle arrest, apoptosis, or cell differentiation. Thus, HDAC inhibitors down‐regulated telomerase activity via suppression of hTERT mRNA expression. Our study identified a novel mechanism for the antiproliferative effects of HDAC inhibitors on prostate cancer cells.

Antiproliferative effects of the histone deacetylase inhibitor FR901228 on small-cell lung cancer lines and drug-resistant sublines

FR901228 is a novel histone deacetylase (HDAC) inhibitor, and its antiproliferative effects on non‐small cell lung cancer cells have been shown in vitro. However, there have been no reports concerning the effects on small‐cell lung cancer (SCLC). We have recently demonstrated that the HDAC inhibitors trichostatin A and sodium butyrate inhibit expression of the catalytic subunit of telomerase (hTERT) mRNA and telomerase activity in prostate cancer cells. The present study was designed to evaluate the effects of FR901228 on proliferation and telomerase activity in SCLC cells in vitro. FR901228 at 5 to 10 nM increased the fraction of cells in the G2/M and sub‐G1 phases of the cell‐cycle, and inhibited the growth of H69, H526 and H82 cell lines. The expression of hTERT mRNA was inhibited 6 hr after treatment, prior to obvious inhibition of cell growth or cell‐cycle distribution shifts. The inhibition of hTERT mRNA expression and telomerase activity was not a consequence of cell‐growth arrest or apoptosis. Cycloheximide blocked the suppression of hTERT mRNA induced by FR901228, and the inhibition of hTERT mRNA by FR901228 required newly synthesized proteins. FR901228 also effectively inhibited growth of etoposide‐resistant UMCC‐1/VP‐16, irinotecan‐resistant PC‐6/SN2‐5H and cisplatin‐resistant H526/CDDP cells having decreased expression of hTERT mRNA and telomerase activity, as well as their parental cells. This implies that SCLC resistant to these key drugs are not cross‐resistant to FR901228. The present study suggests that FR901228 may be a promising drug for chemotherapy of cancers including SCLC, even for refractory or relapsing tumors after conventional chemotherapy.

Interactions of ofloxacin and erythromycin with the multidrug resistance protein (MRP) in MRP-overexpressing human leukemia cells.

ABSTRACT To investigate interactions between the multidrug resistance protein (MRP) and antimicrobial agents, we examined the effects of 12 agents on vincristine sensitivity and efflux of the calcein acetoxy-methyl ester (calcein-AM) of a MRP substrate in MRP-overexpressing cells. Only ofloxacin and erythromycin enhanced sensitivity with increased intracellular vincristine accumulation and inhibited the calcein-AM efflux. Our findings suggest that the two agents are possible MRP substrates and may competitively inhibit MRP function as a drug efflux pump.

Repeated Waon therapy improves pulmonary hypertension during exercise in patients with severe chronic obstructive pulmonary disease

OBJECTIVES Repeated Waon therapy, which uses a far infrared-ray dry sauna system, improved the vascular endothelial function and the cardiac function in patients with chronic heart failure. In patients with chronic obstructive pulmonary disease (COPD), pulmonary hypertension (PH) is associated with a poor prognosis. We investigated whether repeated Waon therapy improves PH, cardiac function, exercise tolerance, and the quality of life (QOL) in patients with COPD. METHODS Consecutive 13 patients with COPD, who met the Global Initiative for Chronic Obstructive Lung Disease criteria and had breathlessness despite receiving conventional treatments, were recruited for this study. They underwent Waon therapy at 60 degrees C in sauna for 15 min following 30 min warmth with blankets outside of the sauna room. This therapy was performed once a day, for 4 weeks. Cardiac function, exercise tolerance, and St. Georges Respiratory Questionnaire (SGRQ) were assessed before and 4 weeks after Waon therapy. RESULTS Right ventricular positive dP/dt at rest elevated significantly from 397 +/- 266 to 512 +/- 320 mmHg/s (p = 0.024) after the therapy. While the PH at rest did not significantly decrease, the PH during exercise decreased significantly from 64 +/- 18 to 51 +/- 13 mmHg (p = 0.028) after Waon therapy. Furthermore, the therapy prolonged the mean exercise time of the constant load of cycle ergometer exercise test from 360 +/- 107 to 392 +/- 97 s (p = 0.032). The total scores of SGRQ improved from 59.7 +/- 16.9 to 55.3 +/- 17.2 (p = 0.002). In addition, no adverse effects were observed related to Waon therapy. CONCLUSIONS Repeated Waon therapy improved right ventricular positive dP/dt, PH during exercise, exercise tolerance and the QOL in patients with severe COPD.

True malignant histiocytosis with trisomy 9 following primary mediastinal germ cell tumor

A 24-year-old Japanese man was admitted due to bloody phlegm in May 2002. A diagnosis of mediastinal germ cell tumor, mixed type involving seminoma, immature teratoma and embryonal carcinoma, was made by transthoracic needle biopsy. Three months later, his complete blood counts revealed pancytopenia with high fever. Examination of bone marrow revealed increased atypical large histiocytes (5.6%) with hemophagocytosis, and thus, hemophagocytic syndrome related to germ cell tumor was diagnosed. In addition, chromosomal analysis of the bone marrow cells revealed a 47, XY, +9 genotype. Chemotherapies for germ cell tumor and hemophagocytic syndrome were performed without any improvement, and he died of diffuse alveolar damage. Autopsy revealed diffuse infiltration of immature histiocytes with hemophagocytosis in the liver, spleen and bone marrow. The atypical histiocytes were positive for CD68 and lysozyme and negative for lymphoid markers, and the diagnosis of true malignant histiocytosis associated with mediastinal germ cell tumor was made. The rare chromosomal abnormality of trisomy 9, a marker for benzene-related leukemia, was seen in the present case without apparent benzene exposure.

Birth Cohort Effects on Incidence of Lung Cancers: A Population‐based Study in Nagasaki, Japan

Smoking prevalence remains high (around 60%) among Japanese males, but smoking initiation among males born in the 1930s decreased by approximately 10% due to economic difficulties following World War II. The present study was designed to examine whether this temporary decline in smoking initiation influenced the subsequent incidence of lung cancers, especially adenocarcinoma. Trends of lung cancer incidence by histological type in both sexes were investigated using data from the population‐based cancer registry in Nagasaki, Japan, from 1986 through 1995. During this period, 5668 males and 2309 females were diagnosed as having lung cancer, and the overall incidence of lung cancers among both sexes remained stable. However, males aged 55–59 years showed a decrease in the age‐specific incidence of adenocarcinoma and squamous‐cell carcinoma (P < 0.05 and P < 0.01, respectively). In birth cohort analyses, the incidence of adenocarcinoma and squamous‐cell carcinoma was lower in the 1935–1939 birth male cohort than in the successive cohorts. The incidence of lung cancers among females with low smoking prevalence did not change with birth cohort. The low smoking initiation among the 1935–1939 birth male cohort appeared to have resulted in a decreased incidence of adenocarcinoma and squamous cell carcinoma among middle‐aged Japanese males. The present study suggests that smoking prevention has an effect in reducing the incidence of lung adenocarcinoma, as well as squamous‐cell carcinoma, among smokers.