Antimetastatic activities and mechanisms of bisdioxopiperazine compounds.

Bisdioxopiperazine (Biz) compounds, including ICRF-154 and razoxane (ICRF-159, Raz), are anticancer agents developed in the UK specifically targeting tumor metastases. Further three bisdioxopiperazine derivatives, bimolane (Bim), probimane (Pro) and MST-16, have been synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, PR China after 1980. Since metastases, the prevailing deadliest pathologic feature of cancer in clinics, have been the main obstacle in cancer therapy, antimetastatic effects and mechanisms of Biz compounds are interesting and significant topics of all time for researchers undergoing the investigations of metastases biology, treatments and patho-physiology. This review addresses and highlights the different inhibitions against metastases in vivo and molecular mechanisms in vitro of Biz compounds especially relating to the inhibitions of tumor metastasis including pathways of inhibitions against angiogenesis, topoisomerase II, calmodulin, sialic acid, fibrinogen, cell-movement and so on. We argue hererin that the systematic exploration of antimetastatic activity and mechanisms of Biz compounds seems to be a shortcut for a final solution of cancer therapy in the future.

Anticancer activities and mechanisms of bisdioxopiperazine compounds probimane and MST-16.

Bisdioxopiperazine compounds, including ICRF-154 and razoxane (ICRF-159, Raz), are anticancer agents developed in the UK specifically targeting tumor metastases. Further two bisdioxopiperazine derivatives, probimane (Pro) and MST-16, have been synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, PR China after 1980. Anticancer activities and mechanisms of Pro and MST-16 compared with Raz, especially for antiproliferative and antimetastatic effects in vivo and in vitro, have been systematically evaluated in this lab as well as by other authors in China. Novel molecular mechanisms especially relating to the inhibition of tumor metastasis between probimane and razoxane have been especially explored and explained, including pathways of inhibitions against calmodulin, sialic acid, lipoperoxidation, fibrinogen, cell-movement and the cell-cycle arrest. The distributions and excretions of (14)[C]-Pro in mice have been carefully monitored long before for explaining the relationship of pharmacological data between in vitro and in vivo evaluations. Pro is more soluble in water and more strongly active against tumors than Raz. In our point of view, Pro seems to inherit and retain most of the targets and pathways of other bisdioxopiperazine compounds currently in use and is cytotoxically more potent than the rest of bisdioxopiperazine compounds. Therefore, there is a great potential and significance for further investigations.

Medicinal chemistry of probimane and MST-16: comparison of anticancer effects between bisdioxopiperazines.

Bisdioxopiperazines, including ICRF-154 and razoxane (ICRF-159, Raz), are a family of anticancer agents developed in the UK, specifically targeting neoplastic metastases. Two other bisdioxopiperazine derivatives, probimane (Pro) and MST-16, were synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. In order to determine the similarities and differences between these agents in medical chemistry, we evaluated the anti-tumor and anti-metastatic effects of Pro and MST-16 in vitro and in vivo against a number of human tumor cell lines and one of murine origin (Lewis lung carcinoma, LLC), and one human tumor xenograft (LAX-83) in nude mice. Our results show that Pro was cytotoxic to human tumor cell lines in vitro (IC50 < 50 microM for 48 h), approximately 3 to 20-fold more than MST-16. Pro and MST-16 manifested more prolonged cytotoxicity than some other first-line anticancer drugs including 5-fluorouacil, vincristine and doxorubicin, and maintain their cytotoxic effects for 4 days in vitro. In animal experiments, Pro and Raz were active against primary tumor growth (35-50 %) and significantly inhibited pulmonary metastasis of LLC (inhibition > 90 %) at dosage below LD(5). Both Raz and Pro were effective in administration schedules of 1, 5 and 9 days. Both Raz (25-32 %) and Pro (55-60 %) caused statistically significant inhibition of the growth of LAX 83 (a human lung adeno-carcinoma xenograft) in nude mice. In this model, Pro was more effective against LAX83 than Raz at equitoxic dosages. These findings suggest that Pro is active against more categories of tumors both in vivo and in vitro, which in some circumstances may make it superior to the currently-used anticancer bisdioxopiperazines, including razoxane and MST-16.

Anti-proliferative effects, cell cycle G2/M phase arrest and blocking of chromosome segregation by probimane and MST-16 in human tumor cell lines.

BACKGROUND: Anticancer bisdioxopiperazines, including ICRF-154, razoxane (Raz, ICRF-159) and ICRF-193, are a family of anticancer agents developed in the UK, especially targeting metastases of neoplasms. Two other bisdioxopiperazine derivatives, probimane (Pro) and MST-16, were synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. Cytotoxic activities and mechanisms of Raz (+)-steroisomer (ICRF-187, dexrazoxane), Pro and MST-16 against tumor cells were evaluated by MTT colorimetry, flow cytometry and karyotyping. RESULTS: Pro was cytotoxic to human tumor cell lines in vitro (IC50<50 microM for 48 h). Four human tumor cell lines (SCG-7901, K562, A549 and HL60) were susceptible to Pro at low inhibitory concentrations (IC50 values < 10 microM for 48 h). Although the IC50 against HeLa cell line of vincristine (VCR, 4.56 microM), doxorubicin (Dox, 1.12 microM) and 5-fluoruouracil (5-Fu, 0.232 microM) are lower than Pro (5.12 microM), ICRF-187 (129 microM) and MST-16 (26.4 microM), VCR, Dox and 5-Fu shows a low dose-related - high cytotoxic activity. Time-response studies showed that the cytotoxic effects of Pro are increased for 3 days in human tumor cells, whereas VCR, Dox and 5-Fu showed decreased cytotoxic action after 24 h. Cell cycle G2/M phase arrest and chromosome segregation blocking by Pro and MST-16 were noted. Although there was similar effects of Pro and MST-16 on chromosome segregation blocking action and cell cycle G2/M phase arrest at 1- 4 microM, cytotoxicity of Pro against tumor cells was higher than that of MST-16 in vitro by a factor of 3- 10 folds. Our data show that Pro may be more effective against lung cancer and leukemia while ICRF-187 and MST-16 shows similar IC50 values only against leukemia. CONCLUSION: It suggests that Pro has a wider spectrum of cytotoxic effects against human tumor cells than other bisdioxopiperazines, especially against solid tumors, and with a single cytotoxic pathway of Pro and MST-16 affecting chromosome segregation and leading also to cell G2/ M phase arrests, which finally reduces cell division rates. Pro may be more potent than MST-16 in cytotoxicity. High dose- and time- responses of Pro, when compared with VCR, 5-Fu and Dox, were seen that suggest a selectivity of Pro against tumor growth. Compounds of bisdioxopiperazines family may keep up their cytotoxic effects longer than many other anticancer drugs.

[Scavenging effects of probimane on active oxygen free radicals by electron spin resonance].

Probimane, dl-1,2-bis (4-morpholine-methyl-3, 5-dioxopiperazin-1-yl) propane, is a new antitumor agent synthesized by Shanghai Institute of Materia Medica, Chinese Academy of Sciences. The scavenging effects of probimane on active oxygen radicals produced in 3 different systems were studied with the ESR spin trapping methods. In Fenton's reaction, probimane remarkably scavenged hydroxyl radicals (.OH) and the rate of scavenging .OH by probimane 0.05 mmol/L was 47%, compared to 5% by vitamin E (VE) and 30% by ascorbic acid (AA). In irradiation riboflavin system, in which superoxide (O2-.) was produced, the agent also had the scavenging effects on O2(-.). The rate of scavenging O2-. by probimane 0.05 mmol/L was 13%, higher than that by VE (7%) but lower than that by AA (90%). In cell system where the active oxygen radicals were produced during the respiratory burst of human neutrophils (Neu) stimulated by TPA (tetradecanoylphorbol acetate), probimane exhibited a dose-dependent scavenging action on the radicals. The rate of the radical scavenging by probimane 0.05 mmol/L was 37%, much higher than that by VE (9%) but lower than that by AA (68%). Probimane had no effect on the rate of oxygen consumption by human Neu, measured with spin probe oxymetry.

Reduction of chronic doxorubicin cardiotoxicity in beagle dogs by bis-morpholinomethyl derivative of razoxane (ICRF-159).

Addition of morpholinomethyl substituents to razoxane (ICRF-159) produced a compound (bis-4-morpholinomethyl-3,5-dioxopiperazinyl-1,2-propane (MM-159) considerably more water-soluble than razoxane. The increased solubility allowed MM-159 to be examined for protective activity against chronic doxorubicin (DXR) cardiotoxicity. Adult beagle dogs of either sex were given, i.v. at 3-week intervals, either DXR (1.75 mg/kg) alone or DXR 15 min after MM-159 (25 mg/kg). Control animals received MM-159 (25 mg/kg) or saline without DXR. The experiment was terminated 3 weeks after the ninth injection (total DXR dose, 15.75 mg/kg). Of the eight animals given DXR alone, five died after receiving seven to eight injections (12.25-14 mg/kg DXR) and the remaining three were killed after eight injections because they were in poor condition. Marked ascites was noted in four of these eight dogs. When frequency and extent of myocardial lesions (vacuolation and myofibrillar loss) were assessed on a scale from 0 to 4+, severe lesions (3+) were present in all eight dogs given DXR alone, but no abnormalities (lesion score 0) were found in the hearts of three of eight dogs given MM-159 and DXR and the five remaining animals in this group had minimal (1+; four dogs) or mild (2+; one dog) alterations. DXR reduced the erythrocyte count, hemoglobin, and hematocrit when administered alone, but not in combination with MM-159. Such protection against DXR hematologic effects was not noted previously when dogs were pretreated with ICRF-187, the d-isomer of razoxane, despite the fact that pretreatment with ICRF-187 was as effective as MM-159 in reducing chronic DXR cardiotoxicity. It remains to be determined whether there are other differences in biological activity between MM-159 and ICRF-187.

Intratumor chemotherapy in combination with a systemic antimetastatic drug in the treatment of Lewis-lung carcinoma.

The effect of an antimetastatic agent plus intratumor chemotherapy was evaluated in mice bearing Lewis-lung carcinoma by measuring survival time and by histological examination. Polymeric flavan-3,4-diol (APF) from avocado seeds, Persea gratissima, administered alone directly into the tumor did not change survival time, although it partially destroyed the primary tumor. However, the drug administered in combination with an antimetastatic, 1,2-bis(3,5-dioxopiperazin-1-yl)ethane (ICRF-154), resulted in an increase in survival time. When 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was used in place of polymeric flavanadiol as an intralesional drug, a significant increase in survival was also achieved. The effect of each drug alone and of their combination was evaluated by "responder analyses". Animals "cured" by the combination and rechallenged with 2 X 10(6) tumor cells showed that immunization could occur.