Extensive and saturable accumulation of paclitaxel by the human platelet

Little is known about the cellular distribution of paclitaxel in humans. In the present study we examined the distribution of [³H]-paclitaxel in human blood. When 1 M paclitaxel was incubated with fresh blood at 37°C, the platelet/plasma concentration ratio was 240±17 (mean±SEM), whereas the red blood cell (RBC)/plasma concentration ratio was only 0.59±0.05. In kinetics experiments using platelet-rich plasma, we observed that the platelet accumulation of paclitaxel was highly temperature- and concentration-dependent. Scatchard analysis of the 37°C uptake data demonstrated a dissociation constant (K _app) of 0.80±0.10 M and a maximal binding capacity of 672±102 pmol/10⁹ platelets. It is proposed that the platelet accumulation of paclitaxel reflects binding to microtubules and may serve as a useful model for binding to less accessible cellular sites.     

Cytostatic and apoptotic effects of paclitaxel in human breast tumors

Purpose: We have previously reported incomplete cytotoxic responses of other human solid tumors (bladder, head and neck, ovarian and prostate) to paclitaxel. This finding is qualitatively different from the nearly complete response observed in monolayer cultures of human cancer cell lines. The present study examined the pharmacodynamics of paclitaxel in human breast tumors. Methods: Three-dimensional histocultures of patient tumors were used. The cytostatic effect was evaluated by measurement of the inhibition of 48-h cumulative bromodeoxyuridine (BrdUrd) incorporation. The apoptotic effect was evaluated in terms of morphological changes and by in situ DNA end labeling. Results: Paclitaxel produced partial cytostasis (∼30% maximum) and induced apoptosis (maximum apoptotic index of 3.3% to 29%) in all 15 tumors. More than 95% of apoptotic cells were BrdUrd labeled, but not all BrdUrd-labeled cells were apoptotic. The maximal apoptotic indices in the tumors were significantly correlated with the BrdUrd labeling index of untreated controls (r ² = 0.63, P < 0.01). The maximum apoptotic effect was observed at a tenfold lower drug concentration (0.1 μM ) compared to the maximum cytostatic effect (1 μM ). Neither of these effects was enhanced by increasing the drug concentration to 10 μM. Conclusions: The pharmacodynamics of paclitaxel in human breast tumors are comparable to those found in other human solid tumors. The labeling of apoptotic cells by BrdUrd and the correlation between the proliferation index and apoptosis suggest that drug-induced apoptosis is linked to cell proliferation and is completed after DNA synthesis. The finding that maximal cytostatic and apoptotic effects of paclitaxel were achieved at or below the clinically achievable concentration of 1 μM suggests further increasing the dose to elevate plasma concentration beyond 1 μM may not improve treatment outcome. Received: 3 July 1997 / Accepted: 6 November 1997     

Cytotoxic activity of a new paclitaxel formulation, Pacliex, in vitro and in vivo

Background The paclitaxel formulation, Taxol (Bristol-Myers Squibb), is one of the most effective anticancer agents used today. However; it is associated with serious side effects believed to be caused by the Cremophor EL used for its formulation.Aim To evaluate the cytotoxic activity of a new paclitaxel formulation, Pacliex (developed by Oasmia Pharmaceutical, Uppsala, Sweden), a mixed micelles preparation in which an amphiphilic synthetic derivative of retinoic acid replaced Cremophor EL/ethanol vehicle.Method In this study, three model systems were used to evaluate the cytotoxic activity of Pacliex and other paclitaxel preparations. The cytotoxic activities of Pacliex, Taxol and paclitaxel in ethanol were investigated against a panel of ten human tumor cell lines using the fluorometric microculture cytotoxicity assay (FMCA). Low- and high- proliferating in vitro hollow fiber model of two cell lines, the leukemia CCRF-CEM and the myeloma RPMI 8226/S cell lines, were used to assess the cytotoxic activity of the three formulations. The in vivo hollow fiber model of the two cell lines was used for assessment of Pacliex and Taxol activity. The [3-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay was utilized to analyze the in vitro and in vivo hollow fiber data.Result Pacliex was somewhat more effective than Taxol in the more sensitive cell lines. The activity of Taxol was more pronounced in the resistant cell lines due to an additive effect of the vehicle used. The three formulations showed similar activity in both the low- and high-proliferating in vitro hollow fiber cultures. The in vivo hollow fiber cytotoxic activity of Pacliex was similar to that of Taxol. Putting all the results together, it was found that all the three formulations had similar in vitro and in vivo activity.Conclusion The three in vitro and in vivo models confirmed the similarity of the cytotoxic activities of Pacliex and Taxol. Considering the above, Pacliex could be an interesting alternative Cremophor EL-free formulation of paclitaxel.     

Effect of paclitaxel (Taxol) alone and in combination with radiation on the gastrointestinal mucosa

: Paclitaxel is a potentially useful drug for augmenting the cytotoxic action of radiotherapy because it has independent cytotoxic activity against certain cancers and blocks cells in the radiosensitive mitotic phase of the cell cycle. However, all rapidly proliferating tissues, both normal and neoplastic, may be affected by this therapeutic strategy. The aim of this study was to define the in vivo response of rapidly dividing cells of the small bowel mucosa to paclitaxel given alone and in combination with radiation.

: Mice were given single IV doses of 10 or 40 mg/kg paclitaxel or four doses of 10 mg/kg paclitaxel at 6, 12, or 24 h intervals. The kinetics of mitotic arrest and apoptosis in jejunal crypts of mice at 1–24 h after treatment were defined histologically. An in vivo stem cell microcolony assay was used to assess the radiosensitizing potential of paclitaxel when radiation was delivered at the peak of mitosis and at 24 h after drug treatment.

: Paclitaxel blocked jejunal crypt cells in mitosis and induced apoptosis in a dose-dependent manner. Fractionating the paclitaxel dose over 1–4 days did not result in any greater accumulation of mitotically blocked cells than did a single dose. Mitosis peaked 2–4 h after paclitaxel and returned to near normal by 24 h. Apoptosis lagged several hours behind mitosis and peaked about 6 h later than mitosis. Despite these kinetic perturbations, there was little or no enhancement of radiation effect when single doses were delivered 2–4 after paclitaxel administration. The maximum sensitizer enhancement ratio of 1.07 observed after a single paclitaxel dose of 40 mg/kg is consistent with independent crypt cell killing. Conversely, when radiation was given 24 h after paclitaxel, a significant protective effect of the drug (SER 0.89–0.92), most probably due to a regenerative overshoot induced by paclitaxel, was observed.

: Stem cells of the jejunal mucosa determining radiation response were not radiosentized by paclitaxel with the drug concentrations and dose delivery schedules used, although additive cytotoxicity was observed with the highest drug dose. A radioprotective effect was observed when radiation was given 24 h after paclitaxel administration.     

Biochemical mechanism of cross-resistance to paclitaxel in a mitomycin c-resistant human bladder cancer cell line

The present study describes the biochemical mechanism(s) of cross-resistance to paclitaxel in a human bladder cancer cell line (J82/MMC-2), which is >9-fold more resistant to mitomycin C (MMC) than parental cells (J82/WT). The IC₅₀ values for paclitaxel in J82/WT and J82/MMC-2 cell lines were 0.7±0.03 and 2.8±0.7 μM, respectively (P<0.05). Thus, the J82/MMC-2 cell line exhibited 4-fold cross-resistance to paclitaxel compared with J82/WT. Intracellular accumulation of [³H]paclitaxel was comparable in J82/WT and J82/MMC-2 cell lines. There were no qualitative or quantitative differences between the J82/WT and J82/MMC-2 cell lines in terms of their -tubulin and β-tubulin contents. Paclitaxel-induced apoptosis could not be detected in either cell line over a wide range of drug concentrations. These results indicate that cross-resistance to paclitaxel in the J82/MMC-2 cell line is not linked to reduced drug accumulation, increased drug efflux, alterations in tubulin content or reduced paclitaxel-induced apoptosis. Paclitaxel-induced DNA strand breakage, however, determined by alkaline elution, was markedly lower in the J82/MMC-2 cell line than in J82/WT. These results suggest that paclitaxel cross-resistance in J82/MMC-2 may be attributed to reduced paclitaxel-induced DNA strand breakage. The precise mechanism of reduced paclitaxel-induced DNA strand breakage in J82/MMC-2 cell line relative to J82/WT cells, however, remains to be elucidated.     

Preclinical oral antitumor activity of BMS-185660, a paclitaxel derivative

Purpose: A water soluble paclitaxel derivative, BMS-185660, identified previously as having parenteral activity comparable with that of the parent drug, was evaluated for antitumor activity when given orally. Methods: Staged subcutaneous (s.c.) tumor models of both murine and human origin were used for this purpose. Results: BMS-185660 achieved levels of activity following oral administration which were comparable with those maximum effects obtained using intravenous (i.v.) paclitaxel. Consecutive daily oral administrations of BMS-185660 resulted in maximum gross log cell kill (LCK) values of 1.7–2.0 in two experiments involving the s.c. Madison 109 murine lung tumor model, which were comparable with the best effects of the derivative injected intravenously, and 0.3 to 0.9 LCK greater than the maximum effects obtained with i.v. paclitaxel; paclitaxel given orally was inactive. Against a human ovarian tumor model with developed resistance to cisplatin (A2780/cDDP), oral BMS-185660 achieved a maximum LCK of 1.8 compared with i.v. paclitaxel, which produced a maximum 2.4 LCK. Also, in the human HCT-116 colon carcinoma model, oral BMS-185660 cured a maximum of seven of eight mice compared with six of seven mice cured with i.v. paclitaxel. The loss in potency between comparably effective intravenously and orally administered doses of BMS-185660 was about four- to five-fold, but since no drug-associated lethality was ever observed following the oral administration of the highest doses of BMS-185660, further dose escalation may have been tolerated. The intermediate metabolite between BMS-185660 and paclitaxel is BMS-181681. This compound was also evaluated orally and found not to be active versus s.c. M109, despite demonstrating good activity by the i.v. route. Conclusion: The comparable activities of both intravenously and orally administered BMS-185660 to intravenously administered paclitaxel, combined with the attribute of improved water solubility, provides a good basis for further derivative development. Received: 10 September 1999 / Accepted: 16 March 2000     

In vitro and in vivo metabolism of paclitaxel poliglumex: identification of metabolites and active proteases

Background The efficacy and tolerability of paclitaxel is limited by its low solubility, high systemic exposure, and a lack of selective tumor uptake. Paclitaxel poliglumex (PPX; XYOTAX™) is a macromolecular drug conjugate that was developed to overcome these limitations; the 2′ hydroxyl group of paclitaxel is linked to a biodegradable polymer, poly-l-glutamic acid, to form an inactive polymeric conjugate. PPX was previously shown to accumulate in tumor tissue, presumably by taking advantage of the hyperpermeable tumor vasculature and suppressed lymphatic clearance in tumor tissue. Methods Because anti-tumor activity requires the release of paclitaxel from the polymer-drug conjugate, the current report characterizes PPX biodegradation and release of paclitaxel as determined by quantitative HPLC/mass spectral analysis. Results The identification of monoglutamyl-paclitaxel metabolites in tumor tissue confirmed the in vivo metabolism of PPX in a panel of mouse tumor models. In vitro characterization of the metabolic pathway suggests that PPX can enter tumor cells, and is metabolized to form both mono- and diglutamyl-paclitaxel cleavage products. The intracellular formation of these intermediate metabolites is at least partially dependent on the proteolytic activity of the lysosomal enzyme cathepsin B; PPX metabolism is inhibited by a highly selective inhibitor of cathepsin B, CA-074. Reduced metabolism of PPX in livers and spleens from cathepsin B deficient mice confirms that cathepsin B is an important mediator of PPX metabolism in vivo; however, other proteolytic enzymes may contribute as well. Conclusions The cathepsin B-mediated release of paclitaxel may have therapeutic implications as cathepsin B is upregulated in malignant cells, particularly during tumor progression.     

TE方案与CE方案治疗复发性小细胞肺癌的对比研究

目的：观察紫杉醇（Taxol）联合足叶乙甙（VP-16）与卡铂（CBP）联合足叶乙甙治疗复发性小细胞肺癌（SCLC）的有效性和安全性.方法：将44例SCLC分为两组,A组20例,用TE方案（Taxol＋VP-16）,B组24例,用CE方案（CBP＋VP-16）.两组的治疗周期均为28天,完成2个周期后评价疗效及毒副作用.结果：TE方案有效率60%（12/20）,CE组有效率25%（6/24）,两组疗效有显著差异（P〈0.05）,两组毒副作用主要表现为骨髓抑制,恶心、呕吐和脱发,TE组有肌肉关节痛.结论：TE方案治疗复发性SCLC的疗效高于CE方案.     

Evidence of enhanced in vivo activity using tirapazamine with paclitaxel and paraplatin regimens against the MV-522 human lung cancer xenograft

Purpose: Tirapazamine (3-amino-1,2,4-benzotriazine 1,4-dioxide; SR 4233) is a bioreductive agent that exhibits relatively selective cytotoxicity towards cells under hypoxic conditions and can enhance the antitumor activity of many standard oncolytics. In the present study we examined the interaction between tirapazamine in vivo with paclitaxel and paraplatin in two- and three-way combination studies using the MV-522 human lung carcinoma xenograft model. Methods: Agents were administered as a single i.p. bolus, with tirapazamine being given 3 h prior to paclitaxel, paraplatin, or their combination. Tumor growth inhibition (TGI), final tumor weights, partial and complete responses, and time to tumor doubling were determined after drug administration. Results: Tirapazamine as a single agent was ineffective against this human lung tumor model. A substantial increase in TGI was seen in animals treated with the triple-agent regimen (tirapazamine-paclitaxel-paraplatin) compared to animals treated with double-agent regimens that did not include tirapazamine. The addition of tirapazamine to paclitaxel-paraplatin therapy resulted in a 50% complete response rate; there were no complete responses seen when only the paclitaxel-paraplatin combination was administered. Time to tumor doubling was also significantly improved with the addition of tirapazamine to the paclitaxel and paraplatin combinations. Tirapazamine did not increase the toxicity of paclitaxel, paraplatin, or their combinations as judged by its minimal impact on body weight and the fact that no toxic deaths were observed with tirapazamine-containing regimens. Conclusions: These results are important since recent studies have suggested that the combination of paclitaxel and paraplatin may be particularly active in patients with advanced stage non-small-cell lung cancer. Since tirapazamine can significantly improve efficacy, but does not appear to enhance the toxicity of paclitaxel and paraplatin, its evaluation in future clinical trials in combination with paclitaxel-paraplatin-based therapy appears warranted. Received: 20 May 1998 / Accepted: 3 September 1998     

Combined action of paclitaxel and cisplatin against wildtype and resistant human ovarian carcinoma cells

Purpose: The combination of paclitaxel (PTX) and cisplatin (DDP) shows good clinical efficacy against ovarian cancer. In order to examine the potential cellular basis for this, and provide leads as to how to optimize the combination, we examined the role of sequence of exposure to PTX and DDP on cell growth in vitro. Methods: Four human ovarian carcinoma cell lines, A121, A2780/WT, A2780/DX5B and A2780/CP3, two human head and neck carcinoma cell lines, A253 and FaDu, and the human ileocecal carcinoma cell line, HCT-8, were treated with PTX + DDP with seven schedules: (A) 96 h exposure to PTX + DDP; (B) 24 h PTX alone, then 72 h PTX + DDP; (C) 4 h DDP alone, then 92 h PTX + DDP; (D) 24 h PTX alone, 4 h DDP alone, then 68 h drug-free; (E) 4 h DDP alone, 24 h PTX alone, then 68 h drug-free; (F) 3 h PTX alone, 1 h DDP alone, then 92 h drug-free; and (G) 1 h DDP alone, 3 h PTX alone, then 92 h drug-free. Each of 66 two-drug experiments included five plates (440 randomly treated wells per experiment). Cell growth was measured by the sulforhodamine B assay. The nature and the intensity of the drug interactions were assessed by fitting a seven-parameter model to data with weighted nonlinear regression, enabling the estimation of an interaction parameter, α, with its standard error. Results: Overall there was very little departure from Loewe additivity: 43 experiments showed Loewe additivity, 10 showed Loewe antagonism, and 13 showed slight Loewe synergy. In vitro Loewe synergy was rare, was small when present, and reproducible only for the A121 and HCT-8 cells exposed to schedule D (24 h PTX prior to 4 h DDP). Isobolographic analysis showed complex combined-action surfaces with regions of local Loewe synergy and antagonism. Conclusion: It appears unlikely that the good clinical efficacy of the combination is primarily caused by a synergistic interaction at the cellular level. Received: 24 October 1996 / Accepted: 5 March 1997     

Enhanced antitumour activity of 6-hydroxymethylacylfulvene in combination with topotecan or paclitaxel in the MV522 lung carcinoma xenograft model

6-hydroxymethylacylfulvene (HMAF; MGI 114; Irofulven) is a semisynthetic analogue of the toxin illudin S, which is a product of the Omphalotus mushroom. MGI 114 induces cytotoxicity against a broad range of solid tumours in vivo, including the drug-refractory MV522 human lung cancer xenograft. In this study, the potential application of MGI 114 in the treatment of lung cancer was explored by evaluating the activity of MGI 114 in combination with either topotecan (TPT) or paclitaxel. Groups of eight nude mice bearing MV522 xenografts were treated with MGI 114, TPT or paclitaxel as single agents and with MGI 114 in combination with TPT or paclitaxel. MGI 114 was administered at doses of 2.5 and 5.0 mg/kg intraperitoneally (i.p.) daily on days 1–5, while TPT and paclitaxel were administered at doses of 0.5 or 1.0 mg/kg and 20 mg/kg, respectively, i.p. on days 1–5. In the single-agent studies, MGI 114, TPT and paclitaxel all resulted in decreased final tumour weights compared with vehicle-treated controls. As single agents, TPT, at the 0.5 mg/kg dose level, and paclitaxel, at the 20 mg/kg dose level, produced partial shrinkages (PSs). All combinations of MGI 114, and either TPT or paclitaxel, produced decrements in final tumour weights compared with monotherapy with the same doses of MGI 114, TPT and paclitaxel. Although all animals treated with the combination of MGI 114 and paclitaxel experienced PSs or complete shrinkages (CSs) (or died), analysis of the time to tumour doubling revealed that the combination of MGI 114 and TPT at 2.5 and 0.5 mg/kg, respectively, was synergistic. These results suggest that cytotoxic activity is enhanced when MGI 114 is combined with either TPT or paclitaxel, and clinical trials to further evaluate these combination regimens are warranted.     

Biodistribution of paclitaxel and poly(l-glutamic acid)-paclitaxel conjugate in mice with ovarian OCa-1 tumor

Purpose: Poly(l-glutamic acid)-paclitaxel (PG-TXL) is a water-soluble paclitaxel (TXL) conjugate made by conjugating TXL to poly(l-glutamic acid) via ester bonds. In preclinical studies, PG-TXL has shown significant antitumor activity against a variety of solid tumors. To elucidate the relationship between tissue distribution and antitumor efficacy of PG-TXL, we studied and compared the biodistribution of PG-TXL and TXL. Methods: Female C3Hf/Kam mice bearing syngeneic ovarian OCa-1 tumors were injected with either [³H]TXL or PG-[³H]TXL at an equivalent TXL dose of 20 mg/kg. Mice were killed at various times after drug injection, and samples of blood, spleen, liver, kidney, lung, heart, muscle, brain, fat, and tumor were removed and the radioactivity counted. In addition, concentrations of free [³H]TXL released from PG-[³H]TXL in the spleen, liver, kidney, and tumor were analyzed by using high-performance liquid chromatography (HPLC). Whole-body autoradiographs of mice killed 1 day and 6 days after administration of PG-[³H]TXL were obtained to study the intratumoral distribution of PG-TXL. Results: When [³H]TXL was conjugated to polymer, the biodistribution pattern of PG-[³H]TXL differed from that of [³H]TXL. Based on area under the tissue concentration-time curve (AUC) values, tumor exposure to [³H]TXL was five times greater when administered as PG-TXL than as TXL formulated in Cremophor EL/alcohol vehicle. Furthermore, concentrations of free paclitaxel released from PG-[³H]TXL remained relatively constant in tumor tissue, being 489, 949 and 552 ng/g tumor tissue at 5, 48 and 144 h after dosing, respectively. Autoradiographic images of mice injected with PG-[³H]TXL revealed that radioactivity was primarily located in the periphery of the tumor on day 1 after drug administration and was homogeneously diffused into the center of the tumor by day 6. Over the 144-h study period, [³H]TXL concentrations, predominantly as the inactive conjugate, were higher in tissues with a more abundant reticular endothelial system (i.e. liver, kidney, spleen, lung) than in tissues with less abundant or lacking RE systems (i.e. muscle, fat, brain). Both [³H]TXL and PG-[³H]TXL were excreted primarily through the hepatobiliary route, with a small fraction of each drug (5% and 8.7%, respectively) excreted into the urine within 48 h. Conclusions: This study indicates that the distribution to tumor tissue was enhanced when [³H]TXL was administered as a macromolecular conjugate, and that free TXL was released and maintained within the tumor for a prolonged period. Thus, the antitumor activity of PG-TXL observed in preclinical studies may be attributed in part to enhanced tumor uptake of PG-TXL. Received: 22 December 1999 / Accepted: 24 May 2000     

维生素D3对黑色素瘤细胞株生长及凋亡的影响

目的研究维生素D3对黑色素瘤细胞株A375生长及凋亡的影响.方法采用四唑氮蓝比色(MTT)法检测细胞增殖,光镜观察细胞形态,流式细胞仪测定细胞周期和凋亡率,末端脱氧核苷酸转移酶介导的原位酶标记(TUNEL)法计数凋亡细胞.结果10-7mol/L的1.25(OH)2D3可以抑制A375增生,改变细胞周期时相分布,致G0/G1期阻滞,加强细胞毒性化疗药物紫杉醇的作用,促进细胞凋亡.结论维生素D3可以作为细胞凋亡诱导剂,成为新一种黑色素肿瘤治疗药物.     

Sequence-dependent cytotoxicity of etoposide and paclitaxel in human breast and lung cancer cell lines

Purpose: To evaluate the effect of schedule on the interaction of etoposide with paclitaxel in vitro against the A549 human lung cancer cell line and the MDA-231 and MCF-7 human breast cancer cell lines. Methods: Exposure schedules that were 24-h concurrent, 24-h sequential, and sequential 24-h with a 24-h intervening drug-free period were quantitatively evaluated by the use of the median-effect principle and the combination index. The clonogenic assay was used to assess cytotoxicity, and calculations were done with computer software. Results: Concurrent exposures were less than additive in two of the three cell lines tested. Sequential 24-hour and sequential 24-h with an intervening 24-h drug-free period showed synergism at high effect levels in all three cell lines. Similar synergistic interactions were found when either agent was administered first. Conclusions: These results show a schedule-dependent cytotoxic interaction between etoposide and paclitaxel in the human lung and breast cancer cell lines evaluated, with optimal synergism occurring with sequential, but not with concurrent, treatment. Received: 19 December 1996 / Accepted: 13 October 1997     

Docetaxel and paclitaxel inhibit DNA-adduct formation and intracellular accumulation of cisplatin in human leukocytes

 The purpose of this study was to determine the mechanism of the pharmacodynamic interaction between docetaxel/paclitaxel and cisplatin. Cisplatin-induced DNA-adducts and cisplatin accumulation were quantitated in peripheral blood leukocytes (WBC). The WBC were obtained from patients treated with docetaxel or paclitaxel in phase I/II studies and were incubated in vitro with cisplatin. In addition, blank whole-blood samples were obtained from patients and healthy subjects and incubated in vitro with cisplatin or docetaxel/paclitaxel and cisplatin. The cisplatin-induced DNA-adduct levels measured in WBC after treatment with docetaxel or paclitaxel were significantly lower than those determined in non-pretreated WBC. Docetaxel and paclitaxel reduced the intracellular accumulation of cisplatin in WBC by 46–47%. If the pharmacodynamic interaction between docetaxel/paclitaxel and cisplatin also occurs in other normal tissues such as bone marrow, it may well contribute to the sequence dependent toxicity that has been observed in clinical studies. Received: 15 February 1995/Accepted: 6 June 1995     

Combined cytotoxic action of paclitaxel and ceramide against the human Tu138 head and neck squamous carcinoma cell line

Purpose: Paclitaxel, a chemotherapeutic agent used in the treatment of recalcitrant ovarian and breast as well as other neoplasms, is being investigated for the treatment of squamous cell carcinoma of the head and neck. Our previous studies have demonstrated that exogenously added ceramide enhances apoptosis in paclitaxel-exposed human leukemic cells. In this study, we showed that exogenous ceramide augmented paclitaxel-induced apoptosis in Tu138 cells in vitro when added simultaneously in combination with the paclitaxel. Methods: The combined cytotoxic effects of paclitaxel and ceramide exposure against Tu138 cells were assessed by an MTT dye assay, cell cycle analysis, TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay, and isobologram analysis for synergistic activity. Results: The MTT dye assay results indicated augmentation of time- and concentration-dependent paclitaxel-mediated cell cytotoxicity by simultaneous ceramide treatment. Paclitaxel treatment of Tu138 cells also resulted in an accumulation of cells in the G₂-M phase of the cell cycle. This paclitaxel-mediated G₂-M phase accumulation decreased significantly with the addition of ceramide, indicating that combined paclitaxel/ceramide treatment resulted in the elimination of Tu138 cells from the S and/or G₂-M phases of the cell cycle. Furthermore, ceramide enhancement of paclitaxel-mediated apoptosis was also detected by the TUNEL assay. Conclusion: Our results suggest that paclitaxel/ceramide combination therapy may be an attractive alternative to conventional methods of chemotherapy for head and neck cancer, and should be further explored. Received: 22 April 1999 / Accepted: 14 March 2000     

Combination chemotherapy with paclitaxel and intraperitoneal cisplatin for ovarian cancer with disseminated lesions in the peritoneum and the diaphragm

Background: In ovarian cancer, the management of micrometastases disseminated in the peritoneal cavity is extremely important. We performed intravenous paclitaxel (PAC) infusion combined with cisplatin (CDDP) intraperitoneal infusion for progressive ovarian cancer. Methods: Twelve patients with progressive epithelial ovarian cancer (FIGO IIIc), which was resected using an optimal method at primary surgery, except for disseminated lesions in the peritoneum and the diaphragm, were studied. At primary surgery, a reservoir was placed in the peritoneal cavity. If metastases were identified in the diaphragm, then another reservoir was also placed in the subdiaphragm (double reservoirs). The basic regimen was set at 175 mg/m² with divided doses of PAC and 75 mg/m² CDDP by intraperitoneal injection. When a double reservoir was used, 30 mg/m² of subdiaphragmatic CDDP and 45 mg/m² of intraperitoneal CDDP were administered. The patients received five courses of this regimen. The response to the therapy was evaluated with tumor markers, and by using cytodiagnoses on the peritoneal washing fluid collected from the reservoirs. Results: After five courses of the chemotherapy, the tumor marker levels and cytodiagnoses of all patients became negative. With reference to adverse effects, grade 3–4 neutropenia was detected in 2 patients (16.6%), peripheral neuropathy was detected in 4 patients (33.3%), and alopecia was detected in 11 patients (91.6%). The median follow-up period was 29.2 months and median progression-free survival was 25.6 months. Conclusion: The combination chemotherapy with intravenous PAC and intraperitoneal CDDP was effective on ovarian cancer with disseminated lesions in the peritoneum and the diaphragm, having only mild adverse effects. Received: February 20, 2002 / Accepted: October 9, 2002 Correspondence to:F. Terauchi     

血管内皮生长因子部分多肽抗血管生成的研究

目的：观察血管内皮生长因子（VEGF）部分多肽（3－4外显子）抗血管生成的作用。方法：抽提LoVo细胞总RNA,进行RT－PCR,克隆VEGF部分多肽cDNA,构建VEGF部分多肽原核表达载体,用限制性酶切和DNA测序进行鉴定,通过聚丙烯酰胺凝胶电泳（SDS－PAGE）分析表达产物,表达产物经亲和层析纯化后,以人脐静脉内皮细胞（HUVEC）和鸡胚尿囊膜（CAM）血管测定其生物学活性。结果：表达产物以可溶性分子形成存在于菌体中,具有良好的抗原性和特异性,并具有抑制HUVEC增殖及CAM血管形成的活性。结论：VEGF部分多肽具有竞争抑制血管生成的功能,在肿瘤生物靶向治疗中具有一定潜在的价值。     

Administration sequence-dependent antitumor effects of paclitaxel and 5-fluorouracil in the human gastric cancer cell line MKN45

Background: The clinical outcome of gastric cancer patients has been improved by combination of 5-fluorouracil (5-FU) and paclitaxel (PXL). However, the optimal schedule of this combination has not been determined. Methods: The efficacies of sequential administrations of 5-FU and PXL on the gastric cancer cell line MKN45 were investigated using a WST-8 colorimetric assay. The cell cycle distribution of each drug was evaluated by flow-cytometry. Furthermore, the mechanism of antitumor activity enhancement by the administration sequence was investigated by western blotting. Results: MKN45 cell growth was significantly inhibited by each drug in a dose- and time-dependent manner. The cytotoxicities of PXL followed by 5-FU were significantly greater than those of 5-FU followed by PXL. The flow-cytometric analysis revealed that PXL exposure caused viable cell accumulation in G2/M phase in a dose-dependent manner. Western blotting showed that PXL exposure followed by 5-FU up-regulated Chk1 and Wee1 protein expressions until PXL removal and 5-FU exposure, when these expressions gradually decreased to their basal levels. 14-3-3σ protein expression was significantly up-regulated upon PXL treatment followed by 5-FU. Interestingly, Mad2 protein expression with PXL treatment followed by 5-FU gradually increased after the PXL removal and 5-FU exposure. Conclusions: PXL followed by 5-FU administration may be the optimal sequence for treatment of gastric cancer. The enhanced viable cell accumulation after PXL pretreatment may be related to G2 arrest. After PXL removal and 5-FU exposure, the cells progressing to M phase may undergo cell death by mitotic catastrophe due to DNA damage caused by 5-FU exposure.     

人CIDE-3蛋白的表达、纯化及多克隆抗体的制备

目的:制备人诱导细胞死亡的DFF45样效应因子-3(CIDE-3)蛋白兔抗人多克隆抗体并进行鉴定。方法:将原核表达载体pET28a( )/CIDE-3转化E.coli BL21(DE3),IPTG诱导表达CIDE-3蛋白,经Ni-NTA Agarose纯化后免疫新西兰白兔,获得人CIDE-3蛋白兔抗血清,并通过免疫印迹(Western blot)、酶联免疫吸附试验(ELISA)及免疫组织化学法对抗体进行鉴定。结果:成功地表达、纯化了人CIDE-3蛋白,与弗氏佐剂乳化后,免疫新西兰白兔,获得高效价的人CIDE-3蛋白兔抗血清,ELISA结果证实该抗体具有较高的亲和性,Western blot及免疫组织化学染色显示证实该抗体能够与人CIDE-3蛋白特异性结合,是一种细胞质蛋白。结论:获得了效价高、特异性较强的人CIDE-3蛋白兔抗血清,为进一步研究人CIDE-3奠定了实验基础。