Antitumor effect of KT6124, a novel derivative of protein kinase inhibitor K-252a and its mechanism of action

Summary Novel derivatives of K-252a, (8R*,9S*,11S*)-(–)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9,10-tetrahydro-8, 11-epoxy-1H,8H,11H-2,7b,11a-triazadibenzo [a,g]-cycloocta[cde]trinden-1-one, an inhibitor of protein kinases and calmodulin-dependent phosphodiesterase, were synthesized and evaluated for their antitumor activity in vitro and in vivo. Of ten derivatives tested, four were active against the P388 murine leukemia i. p.-i. p. system, although K-252a was inactive. Among these derivatives, KT6124 was selected for further biological evaluation studies because its efficacy was the highest. KT6124 was also active against sarcoma 180 and B16 melanoma. It exerted a relatively broad spectrum of antiproliferative activity against 20 human tumor cell lines in vitro. To determine the mechanism(s) of action underlying the antitumor activity of KT6124, we tested the drug for inhibition of protein kinases, including Ca²⁺-and phospholipid-dependent protein kinase (PKC), in intact A431 human epidermoid carcinoma cells in comparison with the PKC-inhibitory activity of K-252a. KT6124 did not antagonize the action of phorbol 12-myristate 13-acetate (PMA) in A431 cells, whereas K-252a did, suggesting that KT6124 may not act on protein kinases in the cells. The interaction of KT6124 with DNA in living cells was examined by the alkaline elution method. KT6124 apparantly exhibited DNA scission both dose-and time-dependently in the target cells. The DNA breakage was dependent on proteinase K treatment, suggesting its possible interaction with DNA-related enzyme(s). These results indicate that KT6124 exerts antitumor activity by acting on DNA or on DNA-related enzyme(s) in tumor cells rather than via the inhibition of protein kinases.     

Ascending contraction and descending relaxation in the distal colon of mice lacking interstitial cells of Cajal.

Recently an essential role of interstitial cells of Cajal (ICC) within myenteric plexus (ICC-MY) was suggested in ascending contraction and descending relaxation in the mouse ileum. The role of ICC in these neural reflexes was examined in the distal colonic segments prepared from the wild type and c-kit mutant, W/W(V) mice, in the present study. Localized distension of the segments from the wild type mice by using a small balloon resulted in ascending contraction and descending relaxation. In the segments from the mutant mice, localized distension also induced these neural reflexes similar to those observed in the wild type mice. Immunohistochemical examination demonstrated that ICC-MY and ICC present in muscle layers (ICC-IM) were severely disrupted in the mutant mouse, but only ICC, present within submucosal plexus (ICC-SMP), remained unchanged. In the small strips with ICC-SMP absent prepared from the mutant mouse, electrical field stimulation induced contraction or relaxation in the absence or presence of atropine, respectively. It was suggested that ICC have no important role in the ascending and descending neural reflexes in the mouse distal colon, this is in direct contrast to the role of ICC-MY in the ileum.     

Diagnosis and treatment of thoracic outlet syndrome

Patients who develop symptoms of thoracic outlet syndrome (TOS) have a predisposing anatomic abnormality. In most patients with TOS, the symptoms are caused by entrapment of the brachial plexus and they do not arise from compression of the subclavian artery, as was previously thought. The tests advocated for diagnosing this common syndrome (i.e., evaluating the positional compression of the artery when the arms are raised, the neck is turned, or the shoulders are braced) cannot accurately diagnose this syndrome. There are two reasons for this. The symptoms of TOS are not related to the compression of the artery in the outlet in 98% of patients, and 75% of normal individuals without symptoms show diminished radial pulse on various provocation tests. We employed four timed provocation tests (minute tests) to diagnose TOS: the timed Morley test, timed Wright test, timed Eden test, and elevated arm stress exercise, all of which are very sensitive. In normal individuals without symptoms, 20% experience transitional symptoms such as slight pain and tiredness, on these tests indicating a subclinical state. TOS is treated by keeping the thoracic outlet wide, this being done either conservatively or surgically. In 1993 and 1994, we conservatively treated 418 of 422 patients with TOS by means of active exercise, a brace, and by block therapy. These measures did not reduce the symptoms in 23 of these patients, so surgical treatment was indicated. In the remaining 4 of the 422 patients, conservative treatment was not indicated and surgery was performed directly. All the patients showed significant clinical improvement of varying degree. Presented at the 69th Annual Meeting of the Japanese Orthopaedic Association, Tokyo, April 12, 1996     

A Rare Case of Biliobiliary Fistula

Abstract: Biliobiliary fistula is a rare clinical entity. The case of a 72 year old female, who presented with epigastric pain and jaundice, is detailed herein. Endoscopic retrograde cholangiopancreatography (ERCP) revealed two stones, one each in the common bile duct and the gallbladder. Continuous endoscopic nasobiliary drainage (ENBD) was performed to relieve obstructive jaundice. Further study with contrast medium administered via the ENBD tube revealed a fistula between the neck of the gallbladder and the common bile duct. The cystic duct was intact. A stone was considered to have migrated into the common bile duct through the fistula. A diagnosis of biliobiliary fistula, Corlette type I was made. However, in this particular case, a biliobiliary fistula was noted at a site below the junction of the cystic duct and common bile duct. Removal of the gallbladder stones was followed by cholecystectomy. The common bile duct was then repaired by utilizing a T-tube. No evidence of malignancy was recognized in the resected gallbladder specimen. In the one year to date since surgery, the patient has been asymptomatic and without signs of biliary disease.     

MOLECULAR GENETICS OF THE SA GENE

1. We have recently identified a candidate gene for rat genetic hypertension, termed S_a, by identifying an mRN A species that shows markedly higher expression in the kidneys of spontaneously hypertensive rats (SHR) than in those of Wistar-Kyoto rats (WKY). 2. Subsequent genetic co-segregation analyses by ourselves and others indicated that the S_a gene locus did indeed influence blood pressure. Moreover, in a preliminary association study, we found an association of a polymorphism of the human S_a gene with essential hypertension. 3. Further studies to identify functions of the Sa gene products are required before reaching a definite conclusion.     

A new operational approach for the piriform sinus fistula

It has been well documented that piriform sinus fistulae often cause suppurative thyroditis; however, when a piriform sinus fistula does not present this symptom, making a correct diagnosis is very difficult. We have experienced 11 cases of a piriform sinus fistula. The conventional operational approach was performed in the initial eight patients, among which there were four recurrences in two patients. Therefore, a new operational approach was introduced for the three most recent cases and one recurrent case. First, the existence of the internal orifice of the fistula is confirmed with a laryngoscope, after which a transverse incision on the neck is made and the abscess dissected. The side wall of the piriform sinus is then opened with the help of a laryngoscope and the bottom part of the mucosa of the sinus transected with the internal orifice of the fistula, after which the fistula is removed en bloc with the bottom part of the sinus and abscess cavity. Using this operation, we experienced no complications and there has been no recurrence so far.This paper was presented at the 23rd Annual Meeting of Pacific Association of Pediatric Surgeons, June 1990 in Kona, Hawaii.     

Management of tight filum terminale.

OBJECTIVE: Tight filum terminale (TFT) is not an uncommon condition, but due to insufficient diagnostic options this syndrome is often overlooked and left untreated. The present study was designed to investigate surgical results concerning neurological perspectives and diagnostic methods for TFT. METHODS: Subjects for this study consisted of 37 patients with TFT who were surgically treated by transecting the filum terminale. We examined the surgical outcomes with regard to low back pain, leg pain, and bladder and bowel dysfunctions, and analyzed neurological and imaging findings. RESULTS: TFT diagnosis was based on the following five criteria; 1) low back pain, 2) non-dermatomal leg pain, 3) bladder-bowel dysfunction, 4) spinal stiffness, and 5) a newly developed positive provocation test for spinal cord extension. CONCLUSION: The survey of surgical outcomes indicated that satisfactory results could be obtained by surgical release of the filum terminale, while neural function was still reversible. In particular, our newly devised provocation test was shown to be highly effective for the early diagnosis of this disorder.