Katsuhiko Hidaka

Involvement of protein kinase in environmental stress-induced activation of human multidrug resistance 1 (MDR1) gene promoter

The human MDR1 gene can be induced in response to various environmental stimuli. To examine whether such stress‐induced activation of the MDR1 gene can be modulated by protein kinase, we employed a stable human cancer KB cell line which contained the bacterial chloramphenicol acetyltransferase (CAT) gene directed by the MDR1 gene promoter. H‐7, a protein kinase C inhibitor, at more than 40 μM inhibited activation of the MDR1 promoter that was induced by ethylmethane sulfonate, 5‐fluorouracil or UV irradiation. DNA binding activity of nuclear factors recognizing the MDR1 promoter was augmented in KB cells treated with UV, but decreased in cells treated concomitantly with H‐7. Okadaic acid alone was able to induce the promoter activation, and this induction was dependent on specific promoter sequences. Okadaic acid also enhanced the DNA binding activity of nuclear factors recognizing the MDR1 promoter. The phosphorylation of transacting factors may modulate the MDR1 gene promoter activity.

Metastatic carcinoma of the gallbladder from renal cancer presenting as intraluminal polypoid mass

SummaryWe report a rare case of secondary involvement of the gallbladder by metastatic renal cell carcinoma. A 71-year-old man was diagnosed as having a polypoid mass within the gallbladder when he underwent right nephrectomy for a renal cell carcinoma. A preoperative diagnosis of simultaneous carcinoma of the gallbladder was made, and extended cholecystectomy with regional lymphadenectomy was performed five months after the initial operation.Postoperative histological examination of the polypoid mass within the gallbladder and a pancreatic mass excised during the second surgery revealed these resected tumors to be identical to the clear cell type of renal cell carcinoma. We feel that this case presents synchronous involvement of the gallbladder and pancreas by metastatic renal cell carcinoma of the right kidney.

A case of hepatocolic fistula after percutaneous drainage for a gas-containing pyogenic liver abscess.

We describe a rare of gas-containing pyogenic liver abscess which penetrated the adjacent colon, forming a hepatocolic fistula, after percutaneous transhepatic abscess drainage (PTAD) had been performed. To the best of our knowledge, this is the first report of hepatocolic fistula associated with a gasforming liver abscess in a diabetic patient, with radiological and surgical confirmation of the fistula.

Secondary mutation resistant to 7-ketocholesterol rescues a sterol metabolic defect in amphotericin B-resistant Chinese hamster cell line

Amphotericin B-resistant mutants isolated from Chinese hamster V79 cells (1) are defective in cholesterol synthesis and more sensitive to an oxygenated sterol analog, 7-ketocholesterol, than their parental cell line. We isolated 7-ketocholesterol-resistant mutants from an amphotericin B-resistant mutant, AMBR-1. The 7-ketocholesterol-resistant mutants had regained increased level of free cholesterol, and they showed somewhat similar dose-response curves to amphotericin B as that of V79. Sterol synthesis from acetate, but not from mevalonate, in 7-ketocholesterol-resistant clones was threefold higher than that of AMBR-1. 7-Ketocholesterol-resistant clone, unlike AMBR-1, could form colonies in the presence of lipoprotein-depleted serum. The results are discussed in terms of probable change in the sterol biosynthetic pathway by the different lesions.

Biomodulation by hyperthermia of topoisomerase II-targeting drugs in human colorectal cancer cells

We examined whether heat stress could enhance the sensitivity of human colon cancer WiDr cells to topoisomerase II‐targeting anticancer agents, etoposide (VP‐16) and teniposide (VM‐26), and also determined the most effective timing for the drug administration after exposure to hyperthermia. Both topoisomerase II contents and topoisomerase II activity were significantly increased in WiDr cells 3 to 12 h after heat stress at 43°C for 1 h, in comparison with those immediately after the heat stress. Cytotoxicity by VP‐16 was most significantly enhanced 3 to 12 h after exposure to 43°C for 1 h, but no synergistic effect was observed when the drug was administered immediately after the heat stress. A combination of VM‐26 with heat stress, but not that of a topoisomerase I‐targeting camptothecin derivative (CPT‐11), or vincristine, showed a synergistic cytotoxic effect on WiDr cells. VP‐16 alone induced cellular accumulation at the G2+M phase, whereas the combination of VP‐16 and heat stress further increased the cell population at the G2+M phase, and decreased S‐phase cells. A possible application of the combination of VP‐16 and hyperthermia in clinical use is discussed.

Hyperthermic sensitivity and cholesterol levels of mammalian cell lines in culture

In this study, we asked whether cholesterol contents were specifically correlated with cellular sensitivity to hyperthermia. To examine this possibility, we employed two isogenic mammalian cell lines, Chinese hamster V79 cell line and its amphotericin B-resistant (AMBr) cell line. AMBr cells had a decreased content of membrane sterols in comparison with V79 cells. Clonogenic assays showed that AMBr cells were more sensitive to hyperthermic treatment at 45 degrees C than V79 cells. Cholesterol contents were increased in AMBr cells by exposure to liposomes containing 1:1 lecithin-cholesterol, and the sterol level was comparable to that of V79 cells. In comparison with untreated AMBr cells, AMBr cells were more resistant to hyperthermia at 45 degrees C when incubated with liposomes containing cholesterol. Treatment of V79 cells with oxygenated sterol, a potent inhibitor of endogeneous sterol synthesis, sensitized the hyperthermic cytotoxicity. Our present data present the hypothesis that cellular cholesterol contents are closely correlated with cellular heat toxicity.

A Case of Gastric Malignant Lymphoma Complicated with Gastro-bronchial Fistula during Neoadjuvant Chemotherapy.

胃悪性リンパ腫はそれ自体は比較的まれな疾患であるが, 胃気管支瘻を伴うことは極めてまれである. 今回, 本疾患の1切除例を経験したので報告する. 症例は81歳の女性. 突然の嘔吐と食欲不振を主訴とし, 精査の結果進行大腸癌と胃悪性リンパ腫の合併と診断した. CT検査にて胃の腫瘍は脾臓, 膵臓, 横隔膜への直接浸潤が疑われ, 胃癌取扱い規約によるstage IIIaより進行した症例と判断したため, 大腸癌に対する右半結腸切除術後, 胃悪性リンパ腫に対し術前化学療法を施行する方針とした. 化学療法施行中に胃穿孔を疑ったが, 膿瘍が左横隔膜下に限局化したため化学療法を継続しえた. さらに化学療法を2クール追加後, 上部消化管造影にて胃気管支瘻が判明した. 化学療法施行終了後2週目に待機手術として胃全摘+脾摘+横隔膜瘻孔部合併切除にて腫瘍を切除しえた. 合併症を生じながらも術前化学療法が著効を呈した症例と考えられた.