Cancer resistance as an acquired and inheritable trait.

AIM: To induce cancer resistance in wild-type mice and detect if the resistance could be inherited to the progeny of the induced resistant mice. Furthermore to investigate the spectrum and immunology of this inherited cancer resistance. MATERIALS AND METHODS: Resistance to with live S180 cancer cells in BALB/c mice was induced by immunization with inactivated S180 cancer cells. The immunization was performed by either frozen/thawed or irradiated cancer cells or cell-free ascitic fluid (CFAF). RESULTS: In all instances the induced resistance was demonstrated to be inheritable. The phenotype was named HICR (heritable induced cancer resistance) and was defined as primary resistant progeny from mice immunized with frozen/thawed or irradiated S180 cells or CFAF obtained from mice with S180 induced ascites. Notably, this resistance was transferred from both male and female mice to the offspring of the immunized mice for at least two generations. Although inheritable, the frequency of cancer-resistant pups was lost over a few generations. Cells from the J774A.1 and RAW cancer cell lines did not induce inheritable cancer resistance, and C57BL/6 mice could not pass on cancer resistance fluorescence-activated cell sorting (FACS) analyses of the peritoneal cells revealed an increased fraction of macrophages. In necropsies of resistant mice no histological signs of cancer or other disease was found. CONCLUSION: Only materials derived from S180 cells could give rise to HICR mice. The molecular basis of the resistance is unknown but may involve epigenetic mechanisms. Other examples of inheritability of acquired phenotypic changes exist but, to our knowledge, this is the first demonstration of acquired, inherited cancer resistance.

A polysaccharide extracted from rice bran fermented with Lentinus edodes enhances natural killer cell activity and exhibits anticancer effects.

The objective of this study was to investigate the activation of natural killer (NK) cells and anticancer effects of exo-biopolymer from rice bran cultured with Lentinus edodes [rice bran exo-biopolymer (RBEP)]. Oral administration of RBEP induced the activation of NK cells in a dose-dependent manner. RBEP also prolonged the life spans of mice transplanted with Sarcoma-180 cells and inhibited growing Sarcoma-180 cells in intraperitoneum. Solid tumor growth was also suppressed by oral administration of RBEP in C57/Bl6 mice transplanted with B16/Bl6 melanoma. Intraperitoneal injection of RBEP was more effective than oral administration at the same dosage in mice with transplanted tumor cells. According to this result, when RBEP directly contacts immune cells, the anticancer activity is higher than by indirectly inducing an immune response through oral administration. Therefore, we suggest that the administration of RBEP may be effective for preventing and/or treating cancer through NK cell activation. However, further studies are needed to elucidate the possible mechanisms of the anticancer activity and to investigate the other beneficial effects of RBEP for the development of a new biological response modifier.

[Effect of reducing caloric intake on mice transplanted with S180 ascitic cancer].

OBJECTIVE: To examine the effect of different reduced caloric intake on mice transplanted with S180 ascitic tumor. METHODS: The institute for cancer research (ICR) mice were randomly divided into control group, 3.0 standard feed (SF) group, 2.0 SF group and 1.3 SF group. The mice in control group were fed enough (about 5 g/d) dietary intake, while the amounts of dietary intake in the latter three groups were scaled down in the proportion of 65%, which were 3.0 g, 2.0 g and 1.3 g standard feed respectively. Meanwhile the essential vitamins were added to the latter three groups to keep the amount of intake the same as that of the control's. RESULTS: For most of the mice, the caloric intake obviously prolonged the mean survival days and improved the life quality was 7.14 kcal/d, and the fasting blood glucose level was 2-3 mmol/L. CONCLUSION: Properly reduced caloric intake and keeping lower blood glucose level is beneficial to prolonging the survival time of mice transplanted with S180 ascitic cancer.

Evaluation of naphthal-NU, a 2-chloroethylnitrosourea derivative of naphthalimide, as a mixed-function anticancer agent.

Naphthal-NU, 2-[2-[3-(2-chloroethyl)-3-nitrosoureido]ethyl]-1H-benz[de]isoquinoline-1,3-dione (Compound 1) has been synthesized as a rationally designed new mixed-function anticancer agent from 1,8-naphthalic anhydride. Its chemical alkylating activity compared with CCNU as standard compound indicated that it possesses greater alkylating activity than the latter. Its antitumour efficacy was assessed in vivo in two murine ascites tumours namely Sarcoma-180 (S-180) and Ehrlich ascites carcinoma (EAC) by measuring the increase in median survival times (MST) of drug treated (T) over untreated control (C) mice. Three clinical drugs namely CCNU (lomustine), endoxan (cyclophosphamide) and 5-fluorouracil (5-FU) were used as positive controls for comparison. Compound 1 has displayed excellent and reproducible antitumoural activity having curative effects in these tumours comparable with CCNU and 5-FU. It has also significantly increased the life span of mice bearing highly advanced tumour for 10 days before the drug challenge. Its toxicity was also assessed in vivo in normal and in S-180 bearing mice by measuring drug-induced changes in hematological parameters, femoral bone marrow and splenic cellularity sequentially on days 9, 15 and 21 following drug treatment at the optimum dose of 50 mg/kg from day 1 to 7. The results indicated that the compound did not adversely affect hematopoiesis. Drug-induced hepatotoxicity and nephrotoxicity were also evaluated at its optimum dose on those days but no such toxicities were detected. It was further screened in vitro in 6 different human tumour cell lines but no significant activity was observed in those lines.

Enhanced antitumor effect of ultrasound in the presence of piroxicam in a mouse air pouch model.

The antitumor effects of piroxicam, a non-steroidal anti-inflammatory drug, on sarcoma 180 cells under ultrasonic irradiation were examined in a mouse air pouch model. When piroxicam was added to sarcoma 180 suspension under ultrasound irradiation (2 MHz, 10 W, 120 s), the mortality rate of tumor cells immediately after the irradiation and the survival rate of mice were significantly higher than those when ultrasound alone was applied, and these effects of piroxicam were dose-dependent. When D-mannitol was used with piroxicam, the mortality rate of the tumors cells after the irradiation was comparable with that when piroxicam alone was applied, but when L-histidine was used concurrently, the antitumor effect was significantly lower than that when piroxicam alone was applied. Histological examinations one week after the ultrasound irradiation in the presence of piroxicam showed sparse tumor tissue in the air pouch and normal appearance of the air pouch and surrounding tissue. The findings suggest that piroxicam enhances the anti-tumor effects of ultrasound in vivo by increasing the production of singlet oxygen without damage to tissue surrounding the tumor.

Synthesis and evaluation of 2-chloroethylnitrosoureas of substituted naphthalimides as mixed-function anticancer compounds.

New mixed function anticancer compounds as 2-chloroethylnitrosoureas of substituted naphthalimides represented by bromonap-NU 4a and chloronap-NU 4b, have been synthesized from 4-bromo- and 4-chloro-l,8-naphthalic anhydride, respectively following a 3-step process. Their chemical alkylating activity compared with nor -HN2 indicated that they possess greater alkylating activity than the latter. Their antitumour efficacies were assessed in vivo in two murine ascites tumours, namely Ehrlich ascites carcinoma (EAC) and Sarcoma-180 (S-180) by measuring the increase in median survival times (MST) of drug treated (T) over untreated control (C) mice. Two standard clinical drugs namely endoxan (cyclophosphamide) and 5-fluorouracil (5-FU) were used as positive controls for comparison. Both of them have displayed substantial and reproducible antitumoral activity in these tumours comparable with 5-FU. These were further screened in vitro in 6 different human tumour cell lines but no significant activity was observed in those lines.

Subcutaneous tumors of mice treated with rhodamine-123 and laser irradiation.

BACKGROUND: Treatment involving photosensitizers and laser irradiation (LIR) in cancer therapy is known as photodynamic therapy (PDT). The purpose of our study was to assess the therapeutic effect of PDT using rhodamine-123 (Rh123) and LIR on subcutaneous tumors (ST) in mice. METHODS: Sarcoma-180 cells (1 x 10(7)) were implanted subcutaneously into the breast area of strain Cr1:CD-1-ICR (BR) female mice. Mice bearing ST were treated with Rh123 or LIR alone, or a combination of both, once a day for 3 successive days. RESULTS: The best therapeutic effect was observed in the group treated with 7.5 mg Rh123 per kilogram of body weight, combined with 75 J/cm2 laser irradiation energy. The group's mortality rate, tumor control rate, mean survival time, and increase in lifespan within 120 days after treatment were 16.7%, 83.3%, 109.4 days, and 135.8%, respectively. The most inhibitory effect on tumor cells was found in the group treated with 15 mg/kg Rh123 and 90 J/cm2 laser irradiation. The biosyntheses of DNA, RNA, and protein in tumor cells of this group was obviously inhibited. CONCLUSION: PDT with the photosensitizer Rh123 and laser irradiation was therapeutically effective in treating subcutaneous tumors of mice. The tumor cells and the syntheses of DNA, RNA, and protein of the tumor cells in these PDT treated mice were obviously inhibited.

Palladium(II) compounds with potential antitumour properties and their platinum analogues: a comparative study of the reaction of some orotic acid derivatives with DNA in vitro.

Ethidium bromide was used to study perturbations induced in salmon sperm DNA complexed with a series of platinum and palladium compounds obtained from chloro and orotic acid derivatives as leaving ligands. The antitumoral activity of these compounds against Sarcoma 180 cells grafted intraperitoneally into mice is correlated with their capacity to interact with DNA in vitro and to perturb its secondary structure. Nevertheless, among these compounds, [Pt(Dach)(3-methyl-orot)] and [Pt(Dach)(5-fluoro-orot)] do not interact with DNA in vitro and are inactive against Sarcoma 180 cells. This lack of activity originates from the fact that strong chelating properties of the ligand prevent hydrolysis of the compounds which are unable to give rise to aquo species which are the reactive ones. On the other hand, the interaction with DNA is not the only prerequisite in order that a compound be active towards tumour cells. In fact, cis-[Pd(NH3)2Cl2] and cis[Pd(Dach)Cl2] are not antitumoral. It is well known that the former undergoes an inactive trans-conformation and that the two compounds hydrolyse very fast assuming that they interact in vivo with a lot of molecules particularly proteins preventing them to reach the DNA, their pharmacological target. By contrast, [Pd(Dach)(3-methyl-orot)] (T/C = 267%) and [Pd(Dach)(5-fluoro-orot)] (T/C = 270%) display significant antitumour activity.

Effects of hyperbaric oxygen on S-180 sarcoma in mice.

The contents of oxygen free radicals (OFRs) and malondialdehyde (MDA) in S-180 sarcoma tissues were measured in four groups of mice: an untreated normoxic group, a normoxic hyperbaric group, a hyperbaric oxygen group, and an HBO group treated with superoxide dismutase (SOD). Measurements were done by electron resonance and spectrophotometry, and observations were made on the volume, weight, necrosis incidence rate of sarcoma tissues, and mortality in all groups. The OFR and MDA content in sarcoma tissues in the HBO group was significantly higher than those of the control groups (P < 0.001); necrosis incidence of sarcoma tissues and the survival rate of mice were higher; the time required for necrosis was shorter, and the volume and weight of sarcoma tissues were smaller and lighter than those of the control groups (P < 0.01). The results suggest that SOD cannot completely eliminate OFRs produced by hyperbaric exposure, although the role of HBO in producing more OFRs can be counterbalanced by SOD to a certain degree. Apparently HBO can check the growth rate of sarcoma and accelerate the necrosis of S-180 sarcoma cells.

Response of mouse sarcoma-180 to bleomycin in combination with radiation and hyperthermia.

The response of a transplantable mouse tumor, S-180, grown intradermally in inbred Balb/c mice, to bleomycin (BLM), irradiation (RT) and hyperthermia (HT) was studied by observing tumor growth changes up to 120 days after treatment. BLM, at 20 mg/kg body weight, and 10 Gy gamma radiation individually produced identical tumor cure, while hyperthermia at 42 degrees C, 60' or 43 degrees C, 30' resulted in a higher tumor response. Treatment with 43 degrees C, 30' after BLM was more effective than hyperthermia after radiation in effecting tumor cure as well as in inducing regrowth delay. In the drug +HT combination the low drug dose was almost equal in effect as the higher drug dose when followed by 43 degrees C, 30'. Combining the three modalities resulted in 100% tumor cure without any local recurrence during the observation period. The micronucleus study 24 h after treatment indicated enhanced cytogenetic damage by the combination treatments.

Combined therapy of mitomycin C and Chinese medical herbs on experimental liver cancer.

In this research, ICR male mice were chosen for intrahepatic implantation of sarcoma 180 tumor cells (1 x 10(7)). The mice were randomly divided into various groups 24 hours after implantation. One of the groups was the tumor control, the others were singly or combinedly treated with mitomycin C (MMC) and Shih Chuan-Ta-Pu-Tang (SCTPT) or Shi-Hung-One (SHO). The results revealed that the mortality rate (MR60) in the tumor control was 100% and the mean survival time (MST60) was 21.11 +/- 10.69 days. The best therapeutic effect appeared in the group treated with the combination of MMC and SHO, its MR6o was 55.0% and MST 60 was 47.0 +/- 13.4 days.

[Controlled prospective trial to evaluate Syosakiko-to in preventing hepatocellular carcinoma in patients with cirrhosis of the liver].

A controlled prospective study was conducted to evaluate the potential of Syo-saiko-to (Xiao-Chai-Hu-Tang) for the prevention of hepatocellular carcinoma (HCC). Pairs of patients were matched for age, sex, presence of HBs antigen and the scores of the severity of liver dysfunction from 260 cirrhotic subjects. We randomly assigned each patient to receive either a conventional medicine (control group), or 7.5 g/day of Syo-saiko-to (trial group). The patients were monitored during 34 months of treatment, and the incidence of HCC in the two groups were compared. Seventeen patients were found to have HCC in the control group, and nine were found to have HCC in the trial group. The incidence of HCC was significantly lower in the trial group. The results of this study suggested that Syo-saiko-to may prevent or delay the emergence of latent HCC in patients with cirrhosis of the liver.

Chronic inflammation impairs hematopoiesis and survival after irradiation.

Our studies show that the induction of a chronic inflammatory lesion in the left hind legs of mice by administration of 5000 rad produced distinct abnormalities of the hematopoietic system. A peripheral neutrophilia accompanied reduced numbers of total nucleated cells, stem cells, stromal cells, erythroblasts, and lymphocytes in the unirradiated femoral marrow, and the spleen was enlarged. Mice with these hematopoietic abnormalities promptly succumbed with bone marrow failure to a sublethal dose of total body irradiation (600 rad TB). Acute inflammation associated with a sterile abscess also impaired survival after 600 rad TB. Hematopoietic abnormalities resembling those in mice with inflammation had been reported in mice bearing a solid extramedullary tumor of sarcoma-180. Concomitant studies showed that bone marrow failure and impaired survival after 600 rad TB administered to mice bearing sarcoma-180 occurred at the same time as that in mice with chronic inflammation. We concluded that chronic inflammation or tumor produced similar abnormalities in the bone marrow and spleen that led to markedly impaired survival and death from bone marrow failure after a sublethal dose of total body irradiation. Although the extramedullary hematopoiesis in the enlarged spleen indicated that its microenvironment supported hematopoiesis, whereas that in marrow was reduced, it was insufficient to compensate for a total body deficit of functional stem cells.

Combined treatments with vitamin A and 5-fluorouracil and the growth of allotransplantable and syngeneic tumors in mice.

The combined effect of retinol palmitate (RP) and 5-fluorouracil (FUra) was examined with the use of allotransplantable and syngeneic murine tumor systems. The ip combined administration of RP (5,000 IU/kg/day) and FUra (5 mg/kg/day, 20 mg/kg/day, or 20 mg/kg/every 3d day) suppressed the tumor growth in ICR/JCL mice given sc inoculations of 5 X 10(6) allotransplantable sarcoma 180 cells and prolonged the survival time of mice inoculated ip with 10(7) tumor cells, as compared with the survival time of mice given the single administration of either RP or FUra. Similar results were obtained when BALB/c mice were inoculated sc with a syngeneic BALB/c Meth A fibrosarcoma and treated with RP (5,000 IU/kg/day) and FUra (20 mg/kg/every 3d day). The growth of Meth A implanted on day 10, as a rechallenge, was significantly suppressed in the group pretreated with RP alone or both RP and FUra for 9 days from day 1. The growth of Meth 1, another syngeneic tumor of BALB/c origin, inoculated on day 10 as a rechallenge tumor was unaffected by the treatment with RP and/or FUra. An immune response to tumor-specific antigens seemed to be involved in the combined effects of these two drugs.

Action of three species of Propionibacteria (P. granulosum, P. acnes, P. avidum) on experimental tumor systems in mice.

The antitumor activity of three different species of Propionibacteria (P. granulosum, P. avidum and P. acnes) against murine Sarcoma 180 and Moloney-Sarcoma-Virus-induced tumor (MSV tumor) was investigated. All three Propionibacteria injected intraperitoneally or intratumorally in multiple doses of 1 mg per mouse appeared to be effective regarding the retardation of growth and the stimulation of regression of Sarcoma 180 in CFW mice. Moreover, the application of Propionibacteria significantly prolonged the survival of Sarcoma-180-bearing mice. No significant differences were found in antitumor effect against Sarcoma 180 between P. granulosum, P. Avidum and P. acnes, but in general, intratumoral injections of all three strains were more effective than intraperitoneal applications. All three strains of Propionibacteria were equally ineffective regarding the retardation of growth and the stimulation of regression of MSV tumors in adult NMRI mice, as assessed after intraperitoneal injections of P. granulosum, P. avidum or P. acnes (1 mg per mouse) 3 days prior to inoculation of virus particles.

Optimization of high-dose methotrexate with leucovorin rescue therapy in the L1210 leukemia and sarcoma 180 murine tumor models.

An analysis of dose and schedule dependence of calcium leucovorin rescue during high-dose methotrexate therapy of ascitic forms of l1210 leukemia and Sarcoma 180 is reported. Schedules with very delayed "low-dose" leucovorin rescue following lethal doses of methotrexate were highly effective in preventing toxicity and achieved a pronounced antitumor effect in both ascites tumor models. Best results were obtained on a schedule of methotrexate (400 mg/kg s.c.) followed 16 to 20 hr later by calcium leucovorin (12 mg/kg s.c.) given once every 2 hr for a total of 5 doses. Progressive increases in the calcium leucovorin dosage on any schedule reduced both toxicity and the antitumor effect of methotrexate in each model. Following a single course of therapy, essentially no toxicity was observed, and the antitumor effects were 2-fold (L1210 leukemia) and 4-fold (Sarcoma 180) greater than a single, maximally tolerated dose (24/kg s.c.) methotrexate alone. An increase in the methotrexate dosage to 800 mg/kg s.c. with or without an increase in calcium leucovorin dosages on the same schedule did not appreciably increase the antitumor effect observed. Two courses of high-dose methotrexate (400 mg/kg s.c.) with leucovorin rescue (24 mg/kg s.c. 16, 20, and 24 hr after drug) given with an 8-day interval between courses doubled the total antitumor effect in each model with no substantial increase in toxicity and gave long-term survivors with Sarcoma 180. The results, overall, are in close agreement with prior prediction for schedule and dose dependence made on the basis of related pharmacokinetic and biochemical studies in murine tumor models reported from this laboratory.

Resistance of mice to Krebs ascites tumour, sarcoma S180 and PC6 plasmacytoma after immunisation with Salmonella enteritidis 11RX.

Resistance to Krebs ascites tumour, sarcoma S180 (ascitic form) and PC6 plasmacytoma can be induced with prior immunisation with live Salmonella enteritidis 11RX. One thousand to ten thousand more tumour cells are needed to give an LD50 after immunisation. Resistance to PC6 could be recalled 137 days after intravenous immunisation with 11RX protein antigen intraperitoneally as measured by prolonged survival or monitoring the death of 5[131I]-iodo-2'-deoxyuridine labelled tumour cells in vivo. The range of tumours to which resistance can be produced by 11RX immunisation suggests that the mechanism of resistance does not involve antigens common to the tumours and Salmonella enteritidis 11RX.

Lethal synergy between sarcoma-180/TG cells and vesicular stomatitis virus in mice.

An interaction between sarcoma-180/TG cells and vesicular stomatitis virus in adult mice resulted in the rapid onset of extensive mortality. This interaction, termed lethal synergy, occurred only at early stages of ascites induction in animals with no prior virus contact. A significant sparing effect conferred by the serotonin antagonist dibenamine was reversed by the administration of serotonin. The cause of death was not determined, but a mechanism involving hypersensitivity is indicated.