A combination of radiotherapy, nitric oxide and a hyperoxygenation sensitizing protocol for brain malignant tumor treatment

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

The Reactive Species Interactome in the Brain

Significance: Redox pioneer Helmut Sies attempted to explain reactive species' challenges faced by organelles, cells, tissues, and organs via three complementary definitions: (i) oxidative stress, that is, the disturbance in the prooxidant-antioxidant defense balance in favor of the prooxidants; (ii) oxidative eustress, the low physiological exposure to prooxidants; and (iii) oxidative distress, the supraphysiological exposure to prooxidants. Recent Advances: Identification, concentration, and interactions are the most important elements to improve our understanding of reactive species in physiology and pathology. In this context, the reactive species interactome (RSI) is a new multilevel redox regulatory system that identifies reactive species families, reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species, and it integrates their interactions with their downstream biological targets. Critical Issues: We propose a united view to fully combine reactive species identification, oxidative eustress and distress, and the RSI system. In this view, we also propose including the forgotten reactive carbonyl species, an increasingly rediscovered reactive species family related to the other reactive families, and key enzymes within the RSI. We focus on brain physiology and pathology to demonstrate why this united view should be considered. Future Directions: More studies are needed for an improved understanding of the contributions of reactive species through their identification, concentration, and interactions, including in the brain. Appreciating the RSI in its entirety should unveil new molecular players and mechanisms in physiology and pathology in the brain and elsewhere.

Spironolactone ameliorates the cardiovascular toxicity induced by concomitant trastuzumab and thoracic radiotherapy

AIM

We aimed to evaluate impact of spironolactone (S) on cardiovascular toxicity of concomitant use of radiotherapy (RT) and trastuzumab (T).

BACKGROUND

S, an aldosterone receptor antagonist, is known to ameliorate the cardiac damage. S ameliorates anthracycline -induced cardiotoxicity, there is no data regarding to effect of S on both T and radiation-induced cardiotoxicity.

MATERIALS/METHODS

Eighty rats were divided into eight groups: group (G) 1 was defined as control group. G2, G3 and G4 were RT, S and T groups respectively. G5, G6, G7 and G8 were RT + T, T + S, RT + S and RT + T + S groups respectively. Rats were sacrificed at 6th hour; 21st and 100th days after RT. Heart and thoracic aorta samples were taken for microscopical examination.

RESULTS

Cardiac inflammation and fibrosis scores and; TGF-β expression were not significantly different within study groups at 6th hour and 21st days of RT. By 100th days of RT fibrosis scores and TGF-β expression in cardiac samples were significantly different between study groups (p values were 0.004 and 0.002 respectively). Pair-wise comparisons revealed that both cardiac fibrosis scores and TGF-β expression levels were higher in G5 when compared to G8 (p values were 0.046 and 0.028 respectively). Moreover the TGF-β expression was higher in G5 when compared to G2 (p = 0.046). We could not demonstrate any significant differences with respect to inflammation, fibrosis and TGF-β expression in thoracic aorta samples between study groups.

CONCLUSIONS

Although S had a protective effect on cardiac tissue it had no protective effect on thoracic aorta when administered with RT + T.

Hyperoxia resensitizes chemoresistant human glioblastoma cells to temozolomide

Temozolomide (TMZ) is standard chemotherapy for glioblastoma multiforme (GBM). Intratumoral hypoxia is common in GBM and may be associated with the development of TMZ resistance. Oxygen therapy has previously been reported to potentiate the effect of chemotherapy in cancer. In this study, we investigated whether hyperoxia can enhance the TMZ-induced cytotoxicity of human GBM cells, and whether and how it would resensitize TMZ-resistant GBM cells to TMZ. TMZ-sensitive human GBM cells (D54-S and U87-S) were treated with TMZ to develop isogenic subclones of TMZ-resistant cells (D54-R and U87-R). All cell lines were then exposed to different oxygen levels (1, 21, 40, or 80 %), with or without concomitant TMZ treatment, before assessment of cell cytotoxicity and morphology. Cell death and survival pathways elicited by TMZ and/or hyperoxia were elucidated by western blotting. Our results showed that TMZ sensitivity of both chemo-sensitive and resistant cells was enhanced significantly under hyperoxia. At the cell line-specific optimum oxygen concentration (D54-R, 80 %; U87-R, 40 %), resistant cells had the same response to TMZ as the parent chemosensitive cells under normoxia via the caspase-dependent pathway. Both TMZ and hyperoxia were associated with increased phosphorylation of ERK p44/42 MAPK (Erk1/2), but to a lesser extent in D54-R cells, suggesting that Erk1/2 activity may be involved in regulation of hyperoxia and TMZ-mediated cell death. Overall, hyperoxia enhanced TMZ toxicity in GBM cells by induction of apoptosis, possibly via MAPK-related pathways. Induced hyperoxia is a potentially promising approach for treatment of TMZ-resistant GBM.

Pharmacokinetic investigation of increased efficacy against malignant gliomas of carboplatin combined with hyperbaric oxygenation

The efficacy of intravenous administration of 400 mg carboplatin/m(2) body surface area over 60 minutes combined with hyperbaric oxygenation (HBO) therapy (0.2 MPa for 60 min) was investigated in 6 Japanese patients (aged 36-67 years) with malignant or brainstem gliomas. Plasma ultra-filtrate samples were analyzed by high-performance liquid chromatography to evaluate the relationship between efficacy and pharmacokinetics. Brain tumor response was evaluated by magnetic resonance imaging as a function of maximum plasma concentration, area under the curve, or mean residence time (MRT) for carboplatin. The MRT for carboplatin in the complete or partial response group (mean +/- standard deviation 4.3 +/- 1.7 hrs; 6 courses in 3 patients) was significantly longer (p < 0.05) than that in the progressive disease group (2.4 +/- 0.1 hrs; 3 courses in 3 patients), but maximum plasma concentration and area under the curve showed no differences. These results suggest that HBO therapy prolongs the biological residence time of carboplatin. MRT for carboplatin may be useful for predicting continuation or modification of chemotherapy and/or clinical antitumor effects in patients with malignant gliomas.

Hyperbaric oxygen in neurosurgery

BACKGROUND

The therapeutic use of pure oxygen, even under hyperbaric conditions, has been well established for about 50 years, whereas the discovery of oxygen occurred 250 years earlier. Many neurosurgical patients suffer from brain tissue damage, due to reduced blood flow, obstructive vessel disease, or as a result of traumatic brain injury.

METHODS AND RESULTS

The application of pure oxygen in these patients is the only method of increasing the O(2) concentration in tissue with impaired blood supply and can minimize secondary impairment of brain tissue.

DISCUSSION

In this brief historical overview we focus on the development and evidence of hyperbaric oxygenation in this specific field of insufficient oxygen supply to the central neural tissue.

CONCLUSION

With the use of modern biological methods and new study designs, HBO has a place in evidence-based treatment of patients with neural tissue damage.

Increased distribution of carboplatin, an anti-cancer agent, to rat brains with the aid of hyperbaric oxygenation

1. The distribution of an anti-cancer agent carboplatin to brains was investigated in combination with hyperbaric oxygenation treatment in rats. 2. After intravenous administration of carboplatin (30 mg kg(-1)) to male Wistar rats, elimination curves of plasma drug concentrations plotted against a time of 45 min were not different with or without hyperbaric oxygenation (at 0.20-0.25 MPa for last 20 min) treatments. 3. Carboplatin concentrations of livers, lungs and kidneys in each group were similar at the endpoint of hyperbaric oxygenation treatment. 4. Under these atmosphere conditions (at 0.10 MPa), carboplatin concentration was at an undetectable level in rat brains (<0.1 microg g(-1) tissue, n = 6). On the contrary, carboplatin was detected in all brains tested at the levels of 0.5 +/- 0.3 microg g(-1) tissue (mean and standard deviation (SD), n = 6), 0.8 +/- 0.5 microg g(-1) tissue, and 0.4 +/- 0.2 microg g(-1) tissue in combination with hyperbaric oxygenation at 0.20, 0.22, and 0.25 MPa, respectively, at the endpoint of hyperbaric oxygenation treatment. 5. The results suggest that carboplatin could be uptaken into rat brains at the detectable levels by the aid of hyperbaric oxygenation, consistently with the reported findings of enhanced transendothelial permeability and improved clinical efficacy of carboplatin combined hyperbaric oxygenation therapy.

Does angiotensin II-aldosterone have a role in radiation-induced heart disease?

Radiation-induced heart disease (RIHD) is the potentially lethal side effect of radiation therapy. Clinical trials and epidemiologic studies show the adverse impact of RIHD on the outcome of long-term cancer survivors. However, what factors affect RIHD and how RIHD develop are not yet clear. On the other hand, as we all known, angiotensin II (Ang II) and aldosterone play a vital pathophysiological role in the common cardiovascular disease, including hypertension, atherosclerosis, heart failure, myocardial infarction and cardiac hypertrophy. The pathophysiology of these various syndromes is similar, starting by prior microvascular injury that leads to subsequent myocardium ischemia, all of which cause late fibrous scars. So the pathophysiology of RIHD is similar to the common heart diseases induced by angiotensin-aldosterone. But the effect of angiotensin-aldosterone on RIHD has little been studied. Thus, in the present hypothesis we suggest that angiotensin II-aldosterone plays an important pathophysical role in RIHD, which was confirmed by our pilot study.

Increased transendothelial permeability of anti-cancer agent carboplatin with the aid of hyperbaric oxygenation

1. The objective was to investigate the transport of an anticancer agent carboplatin across the blood-brain barrier in combination with hyperbaric oxygenation treatment. An in vitro well-validated model of bovine brain capillary endothelial cells was used. 2. A transendothelial transport of doxorubicin, a known P-glycoprotein substrate, was enhanced 1.5-fold by verapamil for 2-h incubation at 37 degrees C. A transendothelial permeability coefficient of carboplatin (1.29 x 10(-3)cm min-1) was also increased 1.8-fold by verapamil. 3. Under the hyperbaric oxygenation conditions (at 0.2 MPa for the first 10 min), the transendothelial transport for 2 h of doxorubicin and carboplatin were increased 1.3- to 1.8-fold by hyperbaric oxygenation, like the suppressive effects of verapamil on P-gp function, without increase of the transport of lucifer yellow, a non P-glycoprotein substrate. 4. Combination of hyperbaric oxygenation treatment and verapamil could not further increase the permeability coefficients of these drugs that were already enhanced by either treatment, implying the P-glycoprotein-mediated carboplatin efflux transport similarly as doxorubicin. 5. Together with our reported high efficacy of carboplatin combined with hyperbaric oxygenation therapy on brain tumours, the present results suggest that carboplatin could be transported by P-glycoprotein, but that this efflux mechanism would be reduced by the hyperbaric oxygenation with the consequences of clinical efficacy.

Hepatic mitochondrial function and brain tumours

PURPOSE OF REVIEW

Therapeutic advances remain modest for patients with malignant brain tumours, due in part to inadequate ability of in-vitro models to mimic the consequences of tumour progression in vivo, which include profound immunosuppression, cytokine dysregulation and microvascular proliferation. This review summarizes recent findings on the wasting consequences of glioma growth, including changes in hepatic metabolism caused by the tumour.

RECENT FINDINGS

Release of proinflammatory cytokines by gliomas leads to anorexia, a sensation of tiredness and fatigue associated with sleep deprivation. The cachexia and associated decrease in relative liver mass that are observed in rats with the most aggressive gliomas may be accounted for by increased activity of the Cori cycle, with the intermediary metabolism of the glioma-influenced liver being directed toward energy utilization rather than energy storage. In these conditions, liver mitochondria exhibit abnormal biogenesis, together with modifications to water dynamics and ion content.

SUMMARY

Improved patient care will result from better understanding of the interactions between brain tumour cells and the immune system, and use of nutritional metabolic therapy to protect tumour-influenced hepatocytes and their mitochondria may improve outcomes.