Peplomycin Research Articles

Retrospective Investigation of Cutaneous Squamous Cell Carcinoma on the Lip Treated with Peplomycin Administered Through a Superficial Temporal Artery.

Continuous intra-arterial (IA) administration of peplomycin (PEP) through a tumor-feeding artery is one of the most effective treatments for cutaneous squamous cell carcinoma (cSCC) in cosmetic areas. In order to determine the effective and safe dose of PEP and the curative rate of IA-PEP, we retrospectively investigated a case series of 24 patients with cSCC on the lips who were treated with IA-PEP. IA-PEP reduced the tumor mass in all 24 cases (100%). A complete response occurred in 17 patients (70.8%), and a partial response occurred in seven (29.2%). Moreover, 17 patients (70.8%) were cured, three patients developed cervical lymph node metastasis (12.5%), and four developed local recurrence (16.7%). Three out of the 24 patients developed interstitial pneumonia (12.5%). Low-dose IA-PEP administered through a superficial temporal artery was a highly effective treatment that achieved a curative response for 70.8% of patients with cSCC on the lips.

Immunomodulatory Effects of Peplomycin on Immunosuppressive and Cytotoxic Cells in the Lesional Skin of Cutaneous Squamous Cell Carcinoma

Background: Continuous intra-arterial administration of peplomycin (PEP) through a tumor-feeding artery using an intravascular indwelling catheter is one of the best treatments for cutaneous squamous cell carcinoma (SCC) on cosmetic areas. Although this reagent is useful for the treatment of SCC, its immunomodulatory effect on the tumor microenvironment is still unknown. Objective/Methods: In this study, we investigated the immunomodulatory effects of PEP on the tumor-infiltrating regulatory T cells and tumor-associated macrophages as well as CD8⁺TIA-1⁺ cytotoxic T cells in the lesional skin of 5 patients with SCC on the lips. Results: Our data suggest that, in addition to the direct antitumor effects, PEP decreased immunosuppressive cells and increased cytotoxic T lymphocytes at the tumor sites, which might maintain antitumor immune response against SCC.

NMR study of peplomycin in aqueous solution. Assignment of resonances by means of two-dimensional spectroscopy

¹H-NMR spectra of peplomycin (PEP) recorded at 400 and, for the first time, 900 MHz at 2 °C were examined. All the spin systems in the PEP molecule were identified through 2D NMR spectroscopy. The use of NMR spectroscopy allowed the unambiguous assignment of 62 protons, generating 47 non-exchangeable and 15 exchangeable signals. The analysis of the signals observed in 2D-NOE spectra indicates that PEP exhibits an extended conformation at 2 °C. A comparison between the solution conformation of apo-PEP and the solution structure of HOO-Co(III)-PEP indicates that the overall structure of apo-PEP is extended in solution, but exhibiting a conformation of the bithiazole (B)-sulfonium (S) unit similar to that of HOO-Co(III)-PEP. The present investigation represents the initial stage of an NMR study of the solution conformation and dynamics of PEP, its derivatives, its metal complexes and the interactions of metallo-PEPs with their target DNA.

Distribution study of peplomycin in rat kidney revealed by immunocytochemistry using monoclonal antibodies

Peplomycin (PEP), an anti-tumor antibiotic related structurally to bleomycin, is widely used, especially for squamous cell carcinoma but shows renal toxicity. We prepared monoclonal antibodies (mAbs) against N-(γ-maleimidobutyryloxy)succinimide-conjugated PEP. The mAbs were monospecific for PEP, but did not react with bleomycin and other anticancer antibiotics. The mAbs enabled us to develop an immunocytochemical (ICC) method for detecting the uptake of PEP in the rat kidney. Two hours after a single i.v. administration of PEP, ICC revealed immunostaining for PEP in irregularly shaped cytoplasmic granules of the proximal tubules in which the microvilli were also stained. Also, staining occurred in the distal tubules and collecting ducts, in both of which we observed scattered swollen cells, reminiscent of necrotic cells, in which both the nuclei and cytoplasm reacted strongly with the antibody. Twenty-four hours after injection, PEP in the proximal tubules completely vanished, but yet significant amounts of PEP remained in both the distal tubules and collecting ducts. Distribution patterns of PEP in cells of the kidneys resembled, in some ways, those of our recent ICC studies for an organic cation aminoglycoside antibiotic gentamicin. This ICC suggests that PEP taken up in the proximal tubule cells is localized in the lysosomes, and organic cation transporters and bleomycin hydrolase might be involved in entrance and/or disappearance of PEP in this cell type. Furthermore, the distal tubules and collecting ducts may be the sites readily affected by some chemotherapeutic agents.

Enhancement of chemosensitivity toward peplomycin by calpastatin-stabilized NF-κB p65 in esophageal carcinoma cells: possible involvement of Fas/Fas-L synergism

Chemosensitivity to anticancer drugs was compared between two human esophageal carcinoma cell lines, T.Tn and YES-6 cells. T.Tn cells were more resistant than YES-6 cells to peplomycin (PEP) but not to the other anticancer drugs such as camptothecin, mitomycin C and cytosine arabinoside. Western blot analysis showed higher expression levels of m-calpain and activated mu-calpain in T.Tn cells than in YES-6 cells. On the other hand, YES-6 cells showed a high expression level of calpastatin, which is a calpain-specific endogenous inhibitor. To investigate whether calpain activity was involved in the chemosensitivity, T.Tn cells were transfected with calpastatin cDNA in an inducible expression vector. The induction of calpastatin was accompanied by increased chemosensitivity to PEP. The increases in calpastatin levels were followed by serial increases in the expression levels of NF-kappaB p65 and Fas. Since purified m- or mu-calpain degraded NF-kappaB p65 in vitro, it is possible that calpastatin suppressed calpain-mediated degradation of NF-kappaB p65. Fas ligand (Fas-L) protein levels increased after treatment of the parental T.Tn and calpastatin-transfected cells with PEP, suggesting the synergism between calpastatin-induced Fas and PEP-induced Fas-L. These results suggest that calpain/calpastatin expression levels are effective markers for predicting the sensitivity of human esophageal carcinoma cells to PEP.

A new animal model of continuous catheterization for investigating mechanisms of arteritis associated with chemotherapy

Although superselective continuous intra-arterial infusion has advantages for cancer therapy, intra-arterial chemotherapy is often interrupted by arterial damage due to arteritis. Therefore, an animal model must be developed to elucidate the mechanism of arteritis associated with continuous anti-cancer drug infusion. We developed a new rat model with which to investigate the causal mechanism(s) of vascular damage associated with continuous catheterization chemotherapy. Chemotherapeutic agents (fluorouracil (5-FU) or peplomycin (PEP)) were continuously administered for 7 days into the abdominal aorta of male Sprague-Dawley rats through a catheter fixed in situ. We found that the incidence of apoptotic endothelial cells of the aorta was higher nearer the tip of the catheter. The incidence of apoptosis was higher in the group treated with 5-FU than with PEP. This animal model will be useful to improve arterial damage among patients undergoing chemotherapy using continuous catheterization.

X-ray absorption spectroscopic investigation of Fe(II)-peplomycin and peplomycin derivatives: the effect of axial ligation on Fe-pyrimidine back-bonding.

X-ray absorption spectroscopy (XAS) is used to study ferrous complexes of a bleomycin (BLM) congener, peplomycin (PEP), and two of its derivatives, iso-peplomycin (ISO) and depyruvamide peplomycin (DP), in which potential axial ligands have been perturbed and removed, respectively. Application of extended X-ray absorption fine structure analysis shows an elongation of the short-distance component of the first coordination sphere in DP and ISO relative to PEP. The XAS pre-edge intensity concomitantly decreases with increased axial perturbation. The short-distance component of PEP is correlated to the Fe-pyrimidine bond and is related to the amount of pi-back-bonding. Thus, the XAS analysis of these complexes provides structural information relevant to their differences in O2 reactivity.

Peplomycin, a bleomycin derivative, induces myofibroblasts in pulmonary fibrosis

To analyse the mechanism by which a bleomycin derivative, peplomycin (PLM) induces pulmonary fibrosis, we investigated differentiation of rat pulmonary fibroblasts to myofibroblasts (MF). In intraperitoneally PLM (5 mg/kg/day)‐injected rats, the peripheries of lungs adjacent to the pleura revealed advanced fibrosis with a small number of α‐smooth muscle actin (α‐SMA)‐positive MF, which ultrastructurally possessed abundant microfilaments and cellular organelles. In the fibrotic tissue, the expression of α‐SMA‐mRNA was detected by in situ reverse transcription‐polymerase (RT‐PCR). The message was strong just after a 2‐week administration of PLM then decreased thereafter, although fibrosis advanced. When pulmonary fibroblasts were separated from saline‐injected rats (N‐Fib) and cultivated for 7 days in the presence of 5 mg/mL PLM, α‐SMA protein was weakly expressed, while the majority of pulmonary fibroblasts separated from PLM‐injected rats (P‐Fib) became positive for α‐SMA in 7‐day cultivation and the expression of α‐SMA in P‐Fib was strongly increased by cultivation in the presence of PLM and transforming growth factor‐β (TGF‐β), but not basic fibroblast growth factor (bFGF) or platelet‐derived growth factor (PDGF), although the cell proliferation was most strongly enhanced by bFGF and only slightly by PLM and TGF‐β. The α‐SMA‐positive cells expressed vimentin, but only weakly expressed desmin. Additionally, P‐Fib generated larger amounts of TGF‐β and bFGF than were generated by N‐Fib. These results indicate that PLM induces pulmonary fibrosis by differentiating fibroblasts to α‐SMA‐positive MF, and that bFGF and TGF‐β play each critical role in the different phases of PLM‐induced pulmonary fibrosis by inducing fibroblast proliferation and transformation, respectively.

Correlation between EGF receptor expression and peplomycin cytotoxicity in squamous cell carcinoma cell lines.

The relationship between sensitivity to anti-cancer agents and EGF receptor expression on squamous cell carcinoma (SCC) cells was investigated. The cytotoxicity of peplomycin (PEP) was correlated with the number of the EGF receptors expressed on the cancer cells, but no correlations were found between the cytotoxicity of adriamycin and cisplatin and EGF receptors. Addition of TNFalpha increased the number of EGF receptors in the SCC cell lines 1.5- to 2-fold. The cytotoxic effect of combined administration of PEP and TNFalpha was correlated with the number of EGF receptors, and produced a 2- to 5-fold increase in IC50 compared with administration of PEP alone. These observations suggest that EGF receptor expression is closely associated with the cytotoxic effect of PEP on SCC cells.

The Upregulation by Peplomycin of Signal Transduction in Human Cells

To explore the mechanism of pulmonary fibrosis by bleomycin and its derivative, peplomycin (PLM), we examined the influence of PLM on signal transduction in human peripheral blood lymphocytes (HL), monocytes (HM) and fibroblasts (HF). Tyrosine phosphorylation of multiple proteins in HL and HM were induced by 0.001 to 0.05 μg/ml and by 0.01 to 0.5 μg/ml of PLM, respectively. In HF, 116-kDa protein was phosphorylated 0.2 to 5 mg/ml of PLM. When HL were treated with 0.01 mg/ml of PLM, phosphorylation of p56lck and activation of extracellular-signal related kinase-2 (ERK2) were induced. ERK2 was also activated in HM. Coordinately, the ratio of p21ras-binding GTP/GDP was increased by PLM. As well as interleukin-2, PLM induced tyrosine phosphorylation of JAK-3. In addition, PLM upregulated the nuclear translocation of nuclear factor-kappa B and the expression of c-myc-mRNA in HL, HM and HF. Furthermore, 0.01 to 0.001 μg/ml PLM enhanced the cytokine generation by HL and HM, and 1 to 5 μg/ml PLM increased cytokine generation and collagen synthesis by HF. These upregulatory effects of PLM were abrogated by pretreatment of the cells with a tyrosine kinase inhibitor. These results indicate that PLM upregulates signal transduction in a variety of cell types and the upregulation may induce pulmonary fibrosis.

Pre-operative radio-chemotherapy enhances apoptotic cell death in oral squamous cell carcinoma.

The effect of pre-operative radio-chemotherapy (RCT) has been examined in a total of 15 oral squamous cell carcinomas (SCCs), in terms of apoptosis (cell loss) and proliferation. All the patients received pre-operative radiation at a dosage of 30 or 40 Gy, as well as anticancer agents including tagaful (FT), 5-fluorouracil (5-FU), bleomycin (BLM) and peplomycin (PEP). Surgical specimens were obtained before and after RCT, and serial sections were prepared for immunohistochemistry for p53 oncoprotein and Ki-67 antigen, as well as for terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL). TUNEL indices (TI; percentage of TUNEL-positive cells in the tumor cells) before and after RCT were 1.2+/-1.1 and 4.7+/-2.9 in the nine well-differentiated oral SCCs, and 1.0+/-0.7 and 3.9+/-2.1 in the six poorly differentiated SCCs, respectively. Similarly, Ki-67 indices (KI; percentage of Ki-67 antigen-positive cells in tumor cells) before and after RCT were 31.1+/-14.2 and 15.8+/-11.1 in the former, and 37.1+/-7.8 and 8.7+/- 13.4 in the latter, respectively. Thus, pre-operative RCT enhanced apoptotic cell death and abated proliferative activity significantly (P<0.05), regardless of histological differentiation. Enhancement of apoptosis was more prominent in the group treated with FT or 5-FU than with BLM or PEP. Oral SCC with >20% of nuclear p53-positive tumor cells was noted in six cases. Enhanced TI and abadement of KI did not differ among the p53-positive and -negative tumors.

In vitro effects of hyperthermia combined with cisplatin or peplomycin on the human maxillary carcinoma cell line IMC-2

We examined the interactive effects of hyperthermia combined with cisplatin (CDDP) (0.5 μg/ml) or peplomycin (PEP) (1.0 μg/ml) on surviving fractions of human maxillary carcinoma IMC-2 cells. Either CDDP or PEP enhanced the 44°C thermosensitivity of thermotolerant cells after heating at 42°C for 2 hours. The development of thermo-tolerance at 42°C with either of the two drugs for 2 hours was not inhibited by CDDP, but it was partially inhibited by PEP. Moreover, for PEP throughout the entire period of 42–44°C step-up heating, the 44°C thermosensitivity of thermotolerant cells after heating at 42°C with PEP for 2 hours was enhanced similarly to that at 44°C with PEP. Heating at 42°C combined with either of the two drugs showed a marked interactive effect.

Preoperative thermochemotherapy of oral cancer using magnetic induction hyperthermia (Implant Heating System: IHS).

Eight patients with primary cancer of the oral cavity were preoperatively treated by combined treatment with hyperthermia and chemotherapy. They received two courses of chemotherapy, which included intra-arterial infusion of 100 mg of cisplatin (CDDP) and 25 mg of peplomycin (PEP) via the superficial temporal artery. The patients also received interstitial hyperthermia for 45 min once a week using the Implant Heating System (IHS) with chemotherapy. IHS consists of ferromagnetic implant, induction coil and generator to produce high frequency magnetic field. The ferromagnetic implant is made of Fe-Pt alloy (Fe: 73%, Pt: 27%), and has a Curie temperature of 68 degrees C. As a result, clinical complete response (CR) was observed in seven patients and partial response (PR) in one, and postoperative pathological examination showed no residual tumour cells in any specimen. Combined interstitial hyperthermia by IHS and chemotherapy is thus found to be an effective therapeutic method for treating oral cancers.

A biochemical evaluation of oral squamous cell carcinoma growth by measurement of specific activity of succinate dehydrogenase in the subrenal capsule assay

An auxiliary method for determination of chemosensitivity with the subrenal capsule assay (SRCA) was developed in which the specific activity of succinate dehydrogenase (SD) of tumor implanted beneath the renal capsule is measured. The appropriate conditions for measuring the specific activity of SD were determined. The chemosensitivity of tumors, derived from six xenograft lines originating from oral squamous cell carcinomas, to peplomycin (PEP), cis-platin (CDDP), and 5-fluorouracil (5-FU) were evaluated by the SRCA and the nude mouse assay (NMA). The chemosensitivity evaluated by NMA displayed a higher degree of correlation with that determined by the improved SRCA than with that determined by the conventional SRCA. The correlations between overall accuracy of prediction with the NMA and those with the conventional SRCA and the improved SRCA were 72.2% and 88.9%, respectively. These findings suggest that our new assay may be useful for evaluation of chemosensitivity in the SRCA.

Contrasting influence of peplomycin and azelastine hydrochloride (Azeptin) on reactive oxygen generation in polymorphonuclear leukocytes, cytokine generation in lymphocytes, and collagen synthesis in fibroblasts.

The influence of peplomycin (PLM) and azelastine hydrochloride (Azeptin) on reactive oxygen (RO) and cytokine generation was examined in human peripheral blood mononuclear leukocytes, polymorphonuclear leukocytes (PMN), and rabbit alveolar macrophages (RAM). In addition, the influence of these drugs on DNA and collagen synthesis was investigated in human gingival and rabbit pulmonary fibroblasts. In vitro, PLM increased the FMLP- and PMA-induced chemiluminescence and superoxide (O2-) generation in human PMN and RAM in a dose-dependent manner. In contrast to PLM, Azeptin dose-dependently suppressed RO generation. Such contrasting actions of PLM and Azeptin were also observed in RAM and PMN obtained from rabbits treated with PLM or Azeptin. Even when human PMN were preincubated with 10-100 micrograms/ml of PLM, the increase in RO generation was negligible in the presence of 10(-5) M Azeptin in the culture medium. No increases in RO generation were observed in RAM or PMN obtained from rabbits that had received PLM (0.1 mg/kg per day) and Azeptin (0.04 mg/kg per day) concomitantly. PLM suppressed superoxide dismutase activity in RAM and human PMN, while Azeptin did not affect this activity. In vitro, PLM up-regulated the release of interleukin-1 beta, interleukin-6, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor both from human cells and from RAM and pulmonary fibroblasts. In the generation of these cytokines, Azeptin abrogated the up-regulatory action of PLM. PLM and Azeptin also had contrasting actions in [3H]thymidine and [3H]proline incorporation in human and rabbit fibroblasts. Furthermore, protein tyrosine phosphorylation, in particular that of a 115-kDa protein in human PMN, was suppressed by Azeptin and enhanced by PLM. These results seem to indicate that up-regulated RO and collagen generation are the causative factors of PLM-induced pulmonary fibrosis and that Azeptin may suppress the adverse effect.

Upregulation of respiratory burst of polymorphonuclear leukocytes by a bleomycin derivative, peplomycin.

The influence of peplomycin (PLM) on the respiratory burst of peripheral blood polymorphonuclear leukocytes (PMN) was investigated. Short-term (5 min) treatment of human PMN with 0.1mu g/ml to 100mu g/ml of PLM increased phorbol myristate acetate (PMA)- and formyl-methionyl-leucyl-phenylalanine (FMLP)-induced luminol-dependent chemiluminescence. PMN, as well as alveolar macrophages from rabbits treated with 0.5 to 1.0 mg/kg of peplomycin per day for 5 days, generated more superoxide (O2-) than the cells from untreated rabbits. In both PLM-treated and untreated PMN, chemiluminescence induced by FMLP and PMA was decreased to less than 50% of the control by staurosporine, superoxide dismutase (SOD) and catalase. However, the peak intensity in PLM-untreated PMN was decreased to about 30% of the control by genistein, while this agent induced a slight decrease in peak intensity in the PLM-treated PMN. Inositol triphosphate and diacyl glycerol levels were not clearly increased by PLM, but an increase of intracellular Ca++ and a shift of protein kinase C (PKC) to the membrane occurred in PMN within 1 min after PLM treatment. Western blotting revealed that the tyrosine phosphorylation of a 115 kDa protein was upregulated by 5 to 50mu g/ml of PLM. While, PLM suppressed SOD activity in alveolar macrophages and PMN. These results seem to indicate that PLM increases the respiratory burst of PMN and macrophages both by way of direct PKC activation and by the upregulation of protein tyrosine phosphorylation. This increased reactive oxygen generation, together with the suppression of SOD activity seems to be tissue-impairing.

培養癌細胞による抗癌剤の効果を高めるための実験的研究 : KB 細胞に対する Biscoclaurine alkaroid と 5-Fluorouracil, Peplomycin との併用効果

In the chemotherapy for oral cancers, treatment results have gradually been improving through development of and improvement in drugs and also through studies on amounts and methods of clinical administration. At the same time, these anticancer drugs have various side effects and some drugs can often cause serious disorders of the lung, kidney, heart, myelopathy, and digestive apparatus. In an attempt to minimize the side effects of 5-Fluorouracil (5-FU) and Peplomycin (PEP) frequently used in the chemotherapy for oral cancers and to enhance additive or multiplicative antitumor effects by combining them with non-anticancer drugs, effects of the combination with Cepharanthin (Ceph), a biscoclaurine alkaroid, were investigated in vitro. For the cultivated cancer cells, KB cells of human pharynx cancer origin were used and cultivated for a fixed period. Then, two anticancer drugs, 5-FU and PEP, were combined with Ceph and administered to the cells. The cells were cultivated for 2, 3, and 5 days and their effects on the KB cells were investigated in terms of growth conditions by t-test and morphology. In addition, as to PEP found to be effective through the combination, combination ratios of PEP to Ceph were investigated. The results were as follows : I. Combination effects of various anticancer drugs with Ceph 1. No significant differences in genesistasis (p<0.01) or in cytomorphologic changes were found in the Ceph alone group (group A), as compared with the control group. Between the 5-FU groups (groups B, C, D) and the PEP groups (groups E, F, G), siginificant differences in genesistasis (p<0.01) and in cytomorphologic changes were found. 2. Between the 5-FU alone group (group B) and the 5-FU-Ceph combined groups (groups C, D), no siginificant genesistasis (p<0.01) nor marked cytomorphologic changes were shown. 3. Between the PEP alone group (group E) and the PEP-Ceph combined groups (groups F, G), siginificant differences in genesistasis (p<0.01) and in cytomorphologic changes were shown. 4. The foregoing results indicated that the combined application of PEP and Ceph in the present experimental concentrations enhanced antitumor effect, but the combination of 5-FU with Ceph did not show clear antitumor effect. II. Combination effects of various combination ratios of PEP to Ceph 1. In the combination ratio of 1 : 3 (group H), as compared with the PEP 0.1μg/ml alone group (group E), each of 3-, and 5-day groups showed siginificant genesistasis (p<0.01). 2. In the combination ratios of 1 : 6 (group I) and 1 : 10 (group F), as compared with the PEP 0.1μg/ml alone group (group E), each of 2-, 3-, and 5-day groups showed siginificant genesistasis (p<0.01). 3. In the PEP 1.0μg/ml alone group (group J), as compared with the combination ratios of 1 : 3 (group H), 1 : 6 (group I), and 1 : 10 (group F), each of 2-, 3-, and 5-day groups showed siginificant genesistasis (p<0.01). 4. In the combination ratio of 1 : 10 (group F), as compared with the combination ratio of 1 : 6 (group I), each of 2-, and 5-day groups did not show siginificant genesistasis (p<0.01). 5. On the basis of the foregoing results, the combination ratios 1 : 6 (group I) and 1 : 10 (group F), as compared with the PEP 0.1μg/ml alone group (group E), enhanced antitumor effect several times. Since Ceph has natural killer activity and can reduce the side effects of PEP as a biological response modifier, the present experiment results gave considerable suggestions for the clinical aspect, although many further experimental studies need to be made.

イエウサギＶＸ２移植舌癌に及ぼすｓｕｐｅｒｏｘｉｄｅ ｄｉｓｍｕｔａｓｅならびにｐｅｐｌｏｍｙｃｉｎの影響に関する実験的研究

It has been recently suggested that active oxygen species such as superoxide (SO) have carcinogenic and anticancer effects. Anticancer agents such as peplomycin (PEP), which are widely used in the treatment of oral cancer, produce pulmonary fibrosis and other side effects which might be caused by SO. Superoxide dismutase (SOD) inactivates SO and protects against physical SO injury.In order to investigate the effects of intravenous PEP and SOD, given singly or in combination, on VX2 carcinoma implanted in the tongue and pulmonary tissue of domestic rabbits, light and electron microscopic studies were performed. The preventive effect of these drugs on lymph node metastasis was determined by histopathological investigation of the positive rate of metastasis (PRM). In addition, the collagen content in the pulmonary tissues and the oxygen partial pressure of arterial blood (PaO2) in the left ventricle were measured.The following results were obtained:1. Anticancer effects on VX2 carcinoma implanted in the tongue were recognized in the PEP and PEP-SOD groups. The values of PRM in the cervical lymph nodes and lung in the PEP and PEPSOD groups were significantly lower than those of the SOD and control groups.2. Electron microscopic examination of VX2 carcinoma cells of the tongue in the PEP and PEPSOD groups showed pycnosis, karyorrhexis, vacuolization and indistinct cell borders. Electron microscopic examination of the pulmonary tissue in the PEP groups showed increased fibroblasts and collagen fibers in the alveolar walls. In the PEP-SOD groups, there were far less inflammatory changes and significantly milder pulmonary fibrosis.3. The collagen content in the PEP-SOD groups was lower than that in the PEP groups.4. The PaO2 of the left ventricle in the PEP-SOD groups was higher than that in the PEP groups.These findings indicated that the use of SOD concurrently with PEP in the chemotherapy of oral cancer, inhibited the induction of pulmonary fibrosis associated with PEP withoutaffecting the anticancer effect of this agent.

ＭＴＴアッセイを用いた口腔癌の制癌剤感受性試験 新鮮腫よう細胞を用いての検討

Fresh surgical specimens from 14 oral cancer patients were used for chemosensitivity tests by MTT assay.The chemosensitivity of 11 out of 19 samples taken from the patients was able to be assessed. The mean optical density (OD) of the control culture containing no drugs was 0.163, which was suitable for measuring the fine sensitivity of cells against various anti-cancer drugs. Squamous cell carcinomas (SCC) were highly sensitive to cisplatin (CDDP), followed by peplomycin (PEP) and 5-fluorouracil (5-FU).Synergistic growth inhibitory effect was detected against 2 SCC when PEP was used in combination with small amounts of CDDP. Thus, MTT assay was considered to be a useful chemosensitivity screening test for oral cancers.

Experimental and clinical evaluation by flow cytometry for the mechanism of combination therapy (cisplatin and peplomycin).

Pharmacologic effects of cisplatin (CDDP) and peplomycin (PEP) on tumor cell kinetics were studied both in vitro and in vivo with the aid of flow cytometry (FCM). Double staining with propidium iodide (PI) and fluorescein isothiocyanate (FITC)-labeled bromodeoxyuridine (BrdU) was used to analyze the cell cycle, and the number of viable cells was determined with fluorescein diacetate (FDA). Effects of combining the 2 agents were also studied to establish the most effective method of combination therapy. Furthermore, these agents were tried clinically on the basis of experimental results. Results showed that CDDP exerted its action at the S and G2M phases in the cell cycle and PEP at the G2M phase. Among the combination regimens in the experiments with CDDP, PEP, and CDDP + PEP as analyzed by FCM, the strongest block on the G2M phase was shown in the one at a 2-day interval, resulting in the most effective killing of the tumor cells. Clinical trial of the combination therapy showed the same results as the in vitro experiment; the therapy proved useful for improving the patient's clinical condition and the results obtained with CT imaging and pathology.