The effect of elemene on lung adenocarcinoma A549 cell radiosensitivity and elucidation of its mechanism

OBJECTIVE: To investigate the effect of elemene on the radiosensitivity of A549 cells and its possible molecular mechanism. METHODS: Apoptosis of A549 cells was detected by flow cytometry and fluorescence microscopy. The effect of double-strand break (DSB) damage repair in A549 cells was evaluated using the neutral comet assay. Protein expression levels were detected using western blotting, and the correlation between protein levels was analyzed. RESULTS: Elemene exhibited a radiosensitizing effect on A549 cells. The level of apoptosis induced by elemene combined with radiation was significantly greater (p<0.01) than that elicited by either radiation or elemene alone. Following radiation and subsequent repair for 24 h, the tail intensity of A549 cells treated with a combination of elemene and radiation was greater than that of cells treated with either elemene or radiation alone (p<0.01). This result indicates that elemene inhibits cellular DSB repair. Both elemene combined with radiation and radiation alone decreased the protein expression of DNA-PKcs and Bcl-2 compared to elemene alone (p<0.01), while p53 protein expression was increased (p<0.01). A negative correlation was observed between DNA-PKcs and p53 expression (r=−0.569, p=0.040), while a positive correlation was found between DNA-PKcs and Bcl-2 expression (r=0.755, p=0.012). CONCLUSIONS: Elemene exhibits a radiosensitizing effect on A549 cells, and its underlying molecular mechanism of action may be related to the downregulation of DNA-PKcs gene expression. .

Does hypericin boost the efficacy of high-power laser? A preliminary experimental study on rats / A hipericina aumenta a eficácia do laser de alta potência? Um estudo preliminar e experimental em ratos

CONTEXT AND OBJECTIVE: Lasers are widely used in treating symptomatic benign prostatic hyperplasia. In current practice, potassium titanyl phosphate (KTP) lasers are the most common type of laser systems used. The aim here was to evaluate the rapid effect of high-power laser systems after application of hypericin. DESIGN AND SETTING: Experimental animal study conducted in the Department of Urology, Gülhane Military Medical Academy, Ankara, Turkey, in 2012. METHODS: Sixteen rats were randomized into four groups: 120 W KTP laser + hypericin; 120 W KTP laser alone; 80 W KTP laser + hypericin; and 80 W KTP laser alone. Hypericin was given intraperitoneally two hours prior to laser applications. The laser incisions were made through the quadriceps muscle of the rats. The depth and the width of the laser incisions were evaluated histologically and recorded. RESULTS: To standardize the effects of the laser, we used the ratio of depth to width. These new values showed us the depth of the laser application per unit width. The new values acquired were evaluated statistically. Mean depth/width values were 231.6, 173.6, 214.1 and 178.9 in groups 1, 2, 3 and 4, respectively. The most notable result was that higher degrees of tissue penetration were achieved in the groups with hypericin (P < 0.05). CONCLUSIONS: The encouraging results from our preliminary study demonstrated that hypericin may improve the effects of KTP laser applications. .

CONTEXTO E OBJETIVO: Lasers são amplamente utilizados no tratamento de hiperplasia benigna de próstata sintomática. Na prática atual, lasers de fosfato de titanilo de potássio (KTP) são os tipos mais comuns usados dos sistemas. O objetivo foi avaliar o efeito rápido do sistema laser de alta potência após a aplicação de hipericina. TIPO DE ESTUDO E LOCAL: Estudo experimental animal, realizado no Departamento de Urologia, Academia de Medicina Militar de Gülhane, Ancara, Turquia, em 2012. MÉTODOS: 16 ratos foram divididos aleatoriamente em 4 grupos: 120W KTP laser + hipericina; 120W KTP laser somente; 80W KTP laser + hipericina; 80W KTP laser somente. Hipericina foi dada intraperitonealmente duas horas antes da aplicação do laser. As incisões a laser foram feitas através do músculo quadríceps dos ratos. A profundidade e a largura das incisões a laser foram avaliadas histologicamente e registradas. RESULTADOS: Para padronizar o efeito do laser foi utilizada a razão entre profundidade e largura. Estes novos valores nos mostraram a profundidade da aplicação do laser de largura por unidade. Os novos valores adquiridos foram avaliados estatisticamente. Os valores da média de profundidade/largura foram 231,6, 173,6, 214,1 e 178,9 nos grupos 1, 2, 3 e 4, respectivamente. O resultado mais notável foi atingir altos graus de penetração tecidual nos grupos com hipericina (P < 0,05). CONCLUSÕES: Os resultados promissores do nosso estudo preliminar mostraram que hipericina pode melhorar os efeitos das aplicações do laser KTP. .

Study of aerobic granulocyte functional activity in the presence of a radiosensitizer [metronidazole]

The in vitro effects of metronidazole on the production of reactive oxygen species by polymorphonuclear [PMN] cells were studied by means of nitroblue tetrazolium and luminol-dependent chemiluminescence. At therapeutic doses of metronidazole [4.98-24.86 microg/mL] significant inhibition of the production of reactive oxygen species was noted in both methods. The inhibitory effect was in a dose-dependent pattern. The data suggest a scavenging mechanism of metronidazole on reactive oxygen species generated by PMN

Optimizing radiotherapy of brain tumours by a combination of temozolomide & lonidamine.

BACKGROUND & OBJECTIVE: Temozolomide (TMZ), a second generation alkylating drug, an effective cytotoxic agent as well as radiosensitizer for malignant brain tumours, has side effects like myelosuppression. Lonidamine (LND) increases the effectiveness of several experimental multiple chemotherapy protocols, without increasing bone marrow toxicities and is effective in brain tumour patients. The objective of the present studies was to investigate whether combining clinically relevant doses of LND and TMZ could increase the proliferation and radiation response of malignant human brain tumour cells in vitro. METHODS: A malignant human glioma (U373MG) cell line was used in these studies. TMZ (20, 40 or 60 microM) or LND (100, 150 or 200 microM), or the combination of both (20 and 100 microM, respectively) in 0.1 per cent dimethyl sulphoxide (DMSO) were added three days after setting up cultures, in six well plates (5 x 10(4) cells/ well). The effects of continuous treatment for two days on proliferation response and cytotoxicity were studied after trypsinization; by cell counts and the uptake of trypan blue dye (0.5%). For the study of radiation (60Co-Gamma-rays, 2 Gy) response, drugs were removed 4 h after irradiation and cultures were grown further in drug free, normal growth medium for another 20 h or 44 h. RESULTS: Continuous presence of TMZ or LND for two days significantly inhibited cell proliferation in a concentration dependent manner. The frequencies of non viable cells increased significantly only at higher concentrations of LND. Combination of 20 microM TMZ with 100 microM LND had additive effects on proliferation response, without affecting cell viability. Short-term drug treatments without irradiation did not induce micronuclei formation. Cell proliferation and viability were also not affected. However, post-irradiation presence of either of these drugs for 4 h significantly reduced the proliferation response, 24 and 48 h after treatments. It was further inhibited by the combination treatment. On the contrary, radiation induced micronuclei formation was enhanced by either of the drugs; which was significantly increased by the combined treatment, 24 h as well as 48 h after irradiation. No effects on cell viability were observed, immediately after these treatments as well as at later time points. INTERPRETATION & CONCLUSION: Our findings showed that combination of TMZ and LND at clinically achievable, low plasma concentrations could inhibit tumour growth, and lonidamine could reduce the dose of temozolomide required for radiosensitization of brain tumours.

Enhancement of radiation induced cell death in chicken B lymphocytes by withaferin A.

Withaferin A (WA), a plant withanolide, has shown significant radiosensitizing effect in vitro and in vivo. Inhibition of DNA repair has been suggested as a mechanism of radiosensitization by WA. To test this, the effect of withaferin A on survival of DT40 chicken B-lymphocyte cell line and its repair deficient single gene mutants Rad54-/-, Ku70-/- and double mutant Ku70-/- /Rad54-/- after irradiation was studied. Exponentially growing cells were treated for 1 hr with 5 microM WA and then exposed to different doses of X-rays. Cell survival was studied by clonogenic assay. WA significantly reduced survival of DT40, Ku70-/- and Ku70-/- /Rad54-/-, but not Rad54-/- cells, suggesting that WA enhances radiosensitivity by interfering with homologous repair, the major pathway of DSB repair in these cells. Inhibition of DNA repair is further indicated in a significant decrease in surviving fraction of DT40 cells by post-irradiation incubation with WA. This could have relevance to cancer radiotherapy.

Correlation of HER1/EGFR expression and degree of radiosensitizing effect of the HER1/EGFR-tyrosine kinase inhibitor erlotinib.

Epidermal growth factor receptor (HER1/EGFR)-mediated signal transduction pathways are important in cellular response to ionizing radiation. High HER1/EGFR expression on cancer cells may contribute to radioresistance. In this pre-clinical study, we evaluated the radiosensitizing effect of erlotinib, a small molecule HER1/EGFR inhibitor in three human cancer cell lines with different HER1/EGFR expression--A431 (very high expression), H157 (moderate expression) and H460 (low expression). Our results demonstrated that A431 was the most radioresistant, while H460 was the most radiosensitive. However, A431 cells were the most sensitive to erlotinib (IC50 = 300 nM) and H460 cells the most resistant (IC50 = 8 microM). H157 had intermediate sensitivity to radiation and erlotinib (IC50 = 3 microM). With 300 nM erlotinib, the radiation dose enhancement ratios (DER) were 1.40, 1.17 and 1.04 in A431, H157 and H460, respectively. Treatment with erlotinib for 24 hr at 300 nM increased G1 arrest by 18.6, 2.0 and 4.8% in A431, H157 and H460, respectively. Erlotinib-induced apoptosis was augmented by radiation in A431 cells only. In conclusion, high HER1/EGFR expression may result in a high degree of radiosensitization with erlotinib combined with radiation. The extent of erlotinib-induced radiosensitization was proportional to HER1/EGFR expression, as well as autophosphorylation of the human epidermal growth factor receptor (HER1/EGFR).

Heterogeneity in the radiosensitizing effects of the DNA ligand hoechst-33342 in human tumor cell lines.

The AT specific minor grove DNA binding ligands bisbenzimidazole derivatives like hoechst-33342 and hoechst-33258 which scavenge free radicals and stabilize macromolecular structure have been shown to afford radioprotection by reducing the induction of DNA damage. However, their ability to inhibit topoisomerases I & II, which play important roles in damage response pathways including DNA repair can enhance radiation damage under certain conditions. Since pool sizes of the topoisomerases differ not only between normal and tumor cells, but also among different tumors, it is anticipated that radiosensitization by hoechst-33342 can vary among tumors. The present studies were, therefore, undertaken to verify this proposition in human glioma (BMG-1 &U-87) and squamous carcinoma (4197 &4451) cell lines which differ in their biological behavior (ploidy, p53, cyclins, bcl, bax etc). Isotoxic concentrations of hoechst-33342 (IC50 i.e producing 50% cell kill) administered immediately following irradiation resulted in the radiosensitization of all cell lines, with a 4&7 fold increase in the cell death (loss of clonogenic cell survival) in U-87&BMG-1 and a 3 fold increase in 4197 &4451 cells. Growth inhibition and increase in cytogenetic damage (micronuclei formation) as well as delayed apoptosis observed under these conditions corroborated well with the enhanced cell death. The ligand induced a significant cell cycle delay, particularly in the late S and G2 phases of BMG-1, U-87 and 4197 cells, while no significant changes could be observed in 4451 cells. Higher endogenous levels of cyclin B1 found in both the glioma cell lines, was enhanced further by the ligand as compared to the squamous carcinoma cells. These results clearly demonstrate that the radiosensitizing effects of the ligand are indeed heterogeneous among different human tumor cell lines. The radiaosensitization is p53 independent and accompanied by enhanced mitotic death (linked to cytogenetic damage) as well as induction of cyclin B1 mediated apoptosis.

Role of topoisomerases in cytotoxicity induced by DNA ligand Hoechst-33342 and UV-C in a glioma cell line.

DNA ligand Hoechst-33342 significantly enhances UV induced cytotoxicity in human glioma cell lines (BMG-1 & U-87) with supra additive increase in cell death, cytogenetic damage, cell cycle delay, apoptosis and inhibition of PLDR. Cytotoxicity of Hoechst-33342 arises due to its interference in the breakage-rejoining reaction of DNA topoisomerases by stabilization of cleavable complexes. Since topoisomerases have also been implicated in the generation of potentially lethal DNA breaks by interaction with various types of DNA damage including UV induced DNA lesions, we investigated in present studies the role of functional topoisomerases in the synergistic cytotoxicity of Hoechst-33342 and UV in a human glioma cell line (BMG-1). Topoisomerase I activity analyzed by the plasmid relaxation assay, was significantly enhanced upon UV irradiation, implying a possible role of this enzyme in the processing of UV induced lesions. However, this increase in the activity was reduced by >50% in cells incubated with Hoechst-33342 for 1 hr prior to irradiation. Imunoflowcytometric analysis of the chromatin bound topoisomerases I and II levels (cleavable complex) using topoisomerases I and II anti-antibodies showed a good correlation between the induction of apoptosis by Hoechst-33342 and UV and enhancement in the level of topoisomerase II mediated cleavable complexes. Induction of apoptosis was associated with a decline in the level of Bcl2. Taken together, these studies show that supra additive cytotoxic effects of UV-C and Hoechst-33342 in BMG-1 cells are consequences of enhanced stabilization of topo II mediated cleavable complexes and alterations in specific signal transduction pathways of apoptosis, besides the inhibition of topoisomerase mediated repair processes.

Ultrastructural effects of two phthalocyanines in CHO-K1 and HeLa cells after laser irradiation

The effects of Photodynamic Therapy using 2nd generation photosensitizers have been widely investigated aiming clinical application treatment of solid neoplasms. In this work, ultrastructure changes caused by the action of two 2nd generation photosensitizers and laser irradiation on CHO-K1 and HeLa (neoplastic) cells were analyzed by transmission electron microscopy. Aluminum phthalocyanine chloride, aluminum phthalocyanine tetrasulfonate chloride and radiation from a semiconductor laser at a fluency of 0.5 J/cm2 (Power=26 mW; lambda=.670 nm) were used. The results showed induction of apoptosis. Such alterations where observed in HeLa but not in CHO-K1 cells after Aluminum phthalocyanine tetrasulfonate chloride (AlPcS4, photodynamic treatment. The Aluminum phthalocyanine chloride (AlPc) photodynamic treatment induced necrosis on the neoplastic cell line, and cytoplasm and nuclear alterations on the normal cell line.

Radiosensitization of a mouse melanoma by withaferin A: in vivo studies.

The radiosensitizing effect of a plant withanolide, withaferin A, on the B16F1 mouse melanoma was studied in vivo. Treatment of 100 mm3 tumours with 10 to 60 mg/kg withaferin A intraperitoneally produced a dose dependent increase in growth delay and volume doubling time. Injection of 30-50 mg/kg withaferin A, followed by 30 Gy local gamma irradiation, significantly enhanced the tumour response. No systemic or local adverse reactions were noted in these groups. The drug was most effective when injected intraperitoneally 1 h before irradiation. However, neither the individual agents nor their combination could produce any complete response (tumour cure). Melanoma is a relatively radioresistant tumour. The present results indicate that the radiation response of this tumour can be significantly enhanced by pretreatment with withaferin A.

Optimization of tumour radiotherapy: Part V--Radiosensitization by 2-deoxy-D-glucose and DNA ligand Hoechst-33342 in a murine tumour.

Radiosensitizing effects of combination of a minor groove DNA ligand, Hoechst-33342, with the glucose analogue and inhibitor of glycolysis, 2-deoxy-D-glucose (2-DG) have been investigated in Ehrlich ascites tumour (EAT) bearing mice following focal irradiation of the tumour with 60Co gamma-rays. Treatment-induced tumour growth delay and tumour free animal survival were evaluated as parameters of radiation response. Focal irradiation of the tumour with a single fraction of 10 Gy induced a moderate delay in tumour growth but did not lead to complete regression in any of the tumours. Intravenous administration of H-342 1 hr before irradiation enhanced radiation-induced growth delay in a dose dependent manner. Complete regression of the tumour was observed only at a dose of 10 mg/kg body wt, leading to a cure (tumour free survival for more than 100 days) rate of 55%. Administration of 2-DG (2 g/kg body wt; i.v.), immediately before irradiation significantly enhanced radiation-induced growth delay and resulted in a cure rate of 45%. In combination with this dose of 2-DG (2 g/kg body wt), H-342 at a lower dose (5 mg/kg body wt) significantly enhanced the cure rate to 66%. H-342 or 2-DG given alone or in combination at the doses investigated here did not show any significant effects on the unirradiated tumour.

A clinical study to assess chlorpromazine as hypoxic cell sensitizer in head & neck cancer treated with conventional radiation.

A randomized prospective study was conducted to evaluate the effectiveness of chlorpromazine as a sensitizer of radiation in advanced head and neck cancers. Patients with unresectable laryngopharyngeal cancers except glottic cancers, with histologically proven squamous cell carcinoma staged III and IV were accrued for the study. Patients received radiation to a total dose of 6000 cGy in six weeks in both the groups except that patients in the study group received 50 mgs Chlorpromazine (CPZ) in divided doses. Fourteen of 20 patients showed complete response in the control group whereas 34 of 38 patients in chlorpromazine treated group had complete regression of the tumour (p = 0.016). The survival was (p = 0.08) better in patients receiving CPZ. This preliminary study shows beneficial effects of chlorpromazine. No adverse effects due to chlorpromazine in conjunction with radiation were documented.

Effect of plumbagin on the radiation induced cytogenetic and cell cycle changes in mouse Ehrlich ascites carcinoma in vivo.

The effect of plumbagin, a naphthoquinone from the roots of the Indian medicinal plant Plumbago rosea, and Cobalt-60 gamma radiation was studied on Ehrlich ascites carcinoma in vivo, taking cytogenetic damage and cell cycle changes as experimental endpoints. Plumbagin (5 mg/kg body wt, P1) administered intraperitoneally produced a significant increase in the percentage of S-phase as well as G2-M cells with a corresponding decrease in the G1 phase at different post-treatment times. Radiation (7.5 Gy, RT) alone produced the classical G2 block at 1 hr, which persisted with a continuous increase throughout the post-treatment observation period. The combination treatment produced a similar effect as that of RT on G2-M cells, but its effect on the G1 phase was more pronounced than the latter. While P1 treatment produced a small increase in the percentage of labeled S-phase cells, combination treatment significantly reduced the labeled S-phase cells with a corresponding increase in the unlabeled fraction. Drug or radiation alone significantly increased micronuclei induction at various post-treatment times and the combination of the two further enhanced this effect additively. The mechanism of interaction of P1 with radiation in bringing about this effect is not clear.

Modification of radio-thermo-chemotherapy by AK-2123 and hydralazine in tumor bearing mice.

The effects of chemical modifiers of hypoxic radiosensitizer, a 3-nitrotriazole derivative AK-2123 (200 mg/kg) before treatment, and vasodilator of hydralazine (HDZ; 5.0 mg/kg) after treatment on tumor growth of SCCVII of mice were investigated in the radio-thermotherapy combined with mitomycin C (MMC; 2.0 mg/kg) or adriamycin (ADM; 3 mg/kg). The tumor treated by 10 Gy alone (tumor doubling time = 7.5 days), MMC alone (6.9 days), and hyperthermia (43 degrees C, 30 min; HT) alone (8.0 days) showed a slight growth delay (control: 5.6 days). Prolonged growth delay (23.2 days) was observed by MMC-radio-thermotherapy (MMC-10Gy/HT) than that (12.4 days) by 10 Gy/HT. The modification of MMC-radio-thermotherapy by HDZ administered between 10 Gy and HT (MMC-10 Gy/HDZ/HT) resulted in the significant prolongation of tumor growth delay (31.7 days). AK-2123 administration before this treatment, (MMC-AK-2123)-10 Gy/HDZ/HT), enhanced a further tumor growth delay (37.6 days) which is equal to that by 50 Gy alone and resulted in the highest dose modifying factor (DMF) of 5.2. While modification of ADM-radio-thermotherapy by AK-2123 and HDZ, (ADM-AK-2123)-10 Gy/HDZ/HT, gave the equal tumor growth delay to that by 30 Gy alone (DMF = 3.1). These high efficacies of radio-thermo-chemotherapy modified by AK-2123 and HDZ may be caused by tumor blood flow reduction.

Radiosensitizing effect of plumbagin on mouse melanoma cells grown in vitro.

Mouse melanoma cells were treated with plumbagin, a naphthoquinone, from the plant Plumbago rosea at 0.5 microgram/ml (PI) for 60 min either alone or followed by 2 Gy gamma radiation (RT). Response to the different treatments was assessed by following the cell growth up to 5 days post treatment. PI alone produced a significant decrease in the cell count on days 3 and 4, whereas RT treatment significantly enhanced the growth inhibitory effect when compared to RT or PI alone. These findings suggests the radiosensitizing effect of PI on mouse melanoma cells in vitro, supporting the earlier in vivo findings.

Mechanistic aspects of modification of radiobiological damage in barley seeds by glutathione and buthionine sulfoximine.

Buthionine sulfoximine (BSO) enhances the radiosensitivity of in vitro mammalian cells, possibly by inhibiting de novo biosynthesis of glutathione (GSH); however, administration of BSO to intact animals results in no effect or possibly radioprotection. Keeping in view that BSO affords radioprotection its physico-chemical action in dry (metabolically inert) and pre-soaked (metabolizing) barley seeds has been investigated with a view that the effects of GSH and BSO on the radiation-induced O2-dependent and - independent components of damage could be unambiguously resolved. It was observed that (i) BSO does not inhibit the uptake of GSH in dry or metabolizing seeds, (ii) BSO also, like GSH, affords radioprotection against post-irradiation O2-dependent damage, and (iii) both additives enhance the O2-independent (i.e. N2- or N2O-mediated) component of damage. An equimolar mixture of these two additives also behaves as either alone on the oxic and anoxic components of radiation damage. Since GSH more efficiently reacts with electrons than it donates an H-atom to the damaged target molecules, and the glutamyl moiety is common to both GSH and BSO, physico-chemical mechanisms possibly involved in the differential modification of oxic and anoxic components are briefly discussed.

Differential modification of radiation damage in 5-bromo-2-deoxy-uridine sensitized human glioma cells and PHA-stimulated peripheral leukocytes by 2-deoxy-D-glucose.

Effects of 5-bromo-2-deoxy-uridine (BrdU) and 2-deoxy-D-glucose (2-DG) on 60-Co-gamma-ray induced damage were studied in monolayer cultures of glioma (BMG-1) cells, and PHA-stimulated peripheral leukocytes from normal donors. Micronuclei formation was used as an index of cytogenetic damage. BrdU and 2-DG treatments did not induce micronuclei formation in unirradiated cultures. Presence of BrdU (0.8 microM) for more than one cell cycle (24 hr) significantly increased gamma-ray (1-4 Gy) induced micronuclei formation in exponentially growing BMG-1 cells. Incubation of irradiated cells under sub-optimal growth conditions (DMEM with 1% serum) for 3 hr, instead of growth medium, significantly decreased micronuclei formation. Post-irradiation presence of 2-DG (5 mM; 3 hr, in DMEM + 1% serum) significantly increased radiation damage. In BrdU sensitized cells also, 2-DG significantly increased radiation damage further. In PHA-stimulated leukocytes from normal donors, 2-DG (5mM, equimolar with glucose; for 2 hr) did not increase gamma-ray (2-Gy, 42 hr after PHA-stimulation) induced micronuclei formation. Pre-irradiation presence of BrdU (1.6 microM) significantly increased micronuclei. On the contrary, 2-DG treatment reduced radiation induced micronuclei formation in BrdU sensitized leukocyte cultures. These results suggest that (i) radiation induced lesions leading to micronuclei formation in proliferating tumour cells, are, at least, partly repairable; (ii) combination of 2-DG could reduce BrdU doses required for radiosensitization of proliferating tumour cells; and (iii) 2-DG could differentially increase radiation damage in BrdU sensitized proliferating tumour cells, while reducing manifestation of damage in normal proliferating cells.

In vivo tumor inhibitory and radiosensitizing effects of an Indian medicinal plant, Plumbago rosea on experimental mouse tumors.

Tumor growth inhibitory and radiosensitizing effects of the alcoholic root extract of P. rosea was studied on experimental mouse tumors, S-180 solid tumor and Ehrlich ascites carcinoma in vivo. Intraperitoneal injection of 50 mg/kg of Plumbago extract (PE) for 10 days starting from 24 hr after intradermal inoculation of S-180 cells in BALB/c mice produced about 16% complete response (CR). The CR% increased with increase in drug dose, to 50% at 100 mg/kg for 10 days. As 100 mg/kg produced toxic side effects, lower doses were used with other treatment modalities, radiation (RT) and hyperthermia (HT). Treatment of 50 mm3 tumor with PE (75 mg/kg) for 10 days with local RT (10 Gy) and/or HT (43 degrees C, 30 min) subadditively increased the CR% and tumor free survival. The combination also significantly reduced the growth rates of uncured tumors. The PE significantly reduced the tumor glutathione content and this effect was markedly enhanced by the combination of the three modalities. PE alone was not very effective in preventing the growth of Ehrlich ascites carcinoma in Swiss mice, though it increased mean survival time and ILS% of the mice. But with radiation it produced a synergistic effect in increasing the tumor inhibition and 120 day animal survival from 10% to 50%. The results demonstrate that though PE may have only a weak antitumor effect, it may be a good candidate for use with radiation to enhance the tumor killing effect.

Antitumor and radiosensitizing effects of Withania somnifera (Ashwagandha) on a transplantable mouse tumor, Sarcoma-180.

Antitumor and radiosensitizing effects of alcoholic root extract of W. somnifera and their modification by heat were studied in vivo on Sarcoma-180 grown on the dorsum of adult BALB/c mouse. Ashwagandha (AT) was injected (ip) at a dose of 500 mg/kg body wt for 10 consecutive days into mouse bearing tumor of 50 +/- 5 mm3, with or without a local treatment of 10 Gy gamma radiation (RT) or hyperthermia at 43 degrees C for 30 min (HT) or both on 5th day of AT. The response was assessed on the basis of tumor regression, growth delay, animal survival and changes in the tumor GSH content. Ashwagandha, RT and HT individually produced 18, 38 and 45% complete response (CR) respectively, but RT gave the best long term survival. Ashwagandha increased the effect of radiation on tumor regression as well as growth delay, but AT + HT gave a better tumor cure. However, both these combinations gave almost identical long term survival, which was not much higher than that produced by RT alone. The combination of Ashwagandha for 10 days with one local exposure to RT followed by HT significantly increased the tumor cure, growth delay of partially responding tumors and animal survival. This combination also significantly and synergistically depleted the tumor GSH level, with no recovery even at 3 hr after treatment. It is concluded that Ashwagandha, in addition to having a tumor inhibitory effect, also acts as a radiosensitizer and heat enhances these effects. The severe depletion in the tumor GSH content by the combination treatment must have enhanced the tumor response, as the inherent protection by the thiol will be highly reduced.

Differential radiosensitization of radioresistant human cancer cells by caffeine.

The effect of caffeine, the methylated xanthine, in sensitizing the lethal action of ionizing radiation in vitro was investigated in human cancer cells which were clinically known to be radioincurable. The tumor lines were hepatocellular carcinoma and colon adenocarcinoma. Plateau phase cultures, after absorbing doses of 2 Gy, survived at a rate of 56.30 per cent for colon cancer and at 66.05 per cent for liver cancer. Both lines were radiosensitized by caffeine but at different potencies. Noteworthily, hepatocellular carcinoma whilst less radiosensitive than colon adenocarcinoma was 4 times more susceptible to caffeine. The lowest effective caffeine concentration for liver cancer was 2 mM which slightly exceeded the anticipated lethal concentration in humans. Research on radiosensitizing effect of methylated xanthines on hepatoma system still remains intriguing. Future work should be pursued with the use of less toxic compounds, such as theobromine.