The Impact of Dose Rate on the Tumor Microenvironment Using Flattening-filter-free Beams

AIMS

Recently, dose delivery technology has rapidly evolved with flattening filter-free beams (FFF), and the biological effects of high dose rates are a matter of interest. We hypothesized that FFF beams at different dose rates obtained with modern linear accelerators have different effects on the TME.

MATERIALS AND METHODS

The B16-F10 melanoma syngeneic tumor model was established, and mice were randomized to 2 different doses (2 Gy and 10 Gy) and 3 different dose rates (1 Gy/min, 6 Gy/min, and 14 Gy/min) along with the control group. Euthanasia was performed on the seventh day after RT, and intracardiac blood was collected for a comet assay. Tumors were harvested and examined histomorphologically and immunohistochemically. Statistical analyses were performed using SPSS software version 23 (SPSS Inc., Chicago, IL, USA).

RESULTS

The daily growth rate was uniform, and no difference was observed between tumor volumes across all three dose rates for each dose. Deoxyribonucleic acid (DNA) damage in blood mononuclear cells was not affected by dose or dose rate. In the TME histomorphological examination, the number of mitosis is less in the 10 Gy arm, whereas the pleomorphism score was greater. Nevertheless, varying dose rates had no effect on the number of mitosis or the pleomorphism score. The severity of the inflammation, cell densities in the TME, and expression of immunohistochemical markers were comparable across all doses and dose rates.

CONCLUSION

In our study involving the B16-F10 syngeneic tumor model, varying dose rates obtained with FFF beams had no effect on tumor volume, blood mononuclear cell DNA damage, or TME parameters. However, in order to fully understand the biological impacts of novel techniques, our study should be validated with alternative preclinical setups.

The Effect of Dose Rate on Tumor Microenvironment in External Beam Radiotherapy

PURPOSE/OBJECTIVE(S)

The fact that treatment can be given at a narrow dose rate range in external radiotherapy (ERT) applications with crude delivery techniques has caused the dose rate to be neglected for a long time. Recently dose delivery technology has rapidly evolved and with the re-introduction of FLASH-RT to the radiation oncology stage, dose rate studies escalated. It is also known that interactions within the tumor microenvironment (TME) play a significant role in tumor prognosis. Herein we aimed to investigate the effect of three different dose rates on TME.

MATERIALS/METHODS

To generate the tumor model, 1 million B16-F10 malignant melanoma cells were subcutaneously injected into the right flank of C57BL/6 mice. RT time was estimated to be 0.5 cm in diameter. Forty-two mice were randomly assigned to the control group, 2 different doses (2 Gy and 10 Gy), and 3 different dose rates (1 Gy/min, 6 Gy/min, and 14 Gy/min). Vernier scale measurements were taken every day to monitor the mice's tumor size. Euthanasia is induced on the seventh day after ERT. Tumor and metastatic organs were harvested, and evaluated histomorphological, and immunohistochemically. Intracardiac blood was collected for the comet assay.

RESULTS

After radiation, the 10 Gy arm's mean tumor size was lower than that of the 2 Gy and control arms (p = 0.01 and p = 0.007). Tumor size did not differ between the 2 Gy and control arms (p = 0.53). Additionally, there was no difference in tumor diameters between low and high doses at different dose rates (p = 0.12, p = 0.21). Blood mononuclear cells in the control arm had less DNA damage than those in the 10 Gy arm (p = 0.04). The 2 Gy and 10 Gy arms did not differ in terms of DNA damage (p = 0.65). Each dose arm was evaluated in terms of dose rates and no significant difference was found (p = 0.79, p = 0.24). The number of mitoses per 10 HPF was assessed during the histological analysis. The number of mitoses in the 10 Gy arm was less than the 2 Gy arm (p = 0.001). There was no difference at different dose rates in the 2 Gy and 10 Gy arms (p = 0.28, p = 0.97). Pleomorphism score was evaluated as mild-moderate and severe (score 1-2-3). In comparison to the 2 Gy and control arms, the 10 Gy arm had a higher pleomorphism score (p = 0.01). The 2 Gy arm and the control arm did not vary from one another (p = 0.04). Pleomorphism scores were comparable across low and high doses at different dose rates (p = 0.35, p = 0.58). Different dose rates resulted in the same staining pattern with aSMA and SOX-10.

CONCLUSION

In our study involving the B16-F10 syngeneic tumor model, we could not find a significant effect of three different dose rates on TME. With constantly improving treatment techniques, larger dose rates are going to be achieved. Owing to this, protocols should also list dose rate as a treatment variable. This project was supported by the TÜBİTAK, Short Term R&D Funding Program.

Can Peripheral Blood Systemic Immune Response Parameters Predict Oncological Outcomes in Patients with Non-Muscle-Invasive Bladder Cancer?

Background

Many studies have investigated most cancer types - associations with systemic inflammatory response (SIR) parameters. Aim: This study investigated predictive values of SIR parameters in oncological outcomes and survival - to primary non-muscle-invasive bladder cancer (NMIBC) patients.

Materials and Methods

We analyzed 74 primary NMIBC patients. Clinical features, laboratory results, and tumor characteristics were recorded. In addition, the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), serum C-reactive protein, albumin-to-globulin ratio (AGR), and modified Glasgow prognostic scores (mGPS) were calculated.

Results

The - mean age of the patients was - 67.41 ± 11.31 years, and the follow-up duration was 38.77 ± 19.53 months. We - found no significant NLR, CRP, and AGR - correlations with tumor characteristics and oncological outcomes. There were significant - correlations between MLR and pathological-T-stage and the PLR, pathological-T-stage, and tumor count. Carcinoma in situ was associated with a high mGPS. Multivariate analysis revealed no significant - correlations between systemic inflammatory response parameters and oncological outcomes. Patients with a high mGPS had poor cancer-specific survival. Increased NLR was associated with reduced overall survival.

Conclusions

This study revealed no significant correlation between SIR parameters and oncological outcomes. Therefore, we need more reliable indicators than SIR parameters in NMIBC patients in clinical practice.

Evaluation of trace elements associated with antioxidant enzymes in blood of primary epithelial ovarian cancer patients

Epithelial ovarian cancer (EOC) has been associated with oxidative stress (OS) due to epithelial inflammation which makes ovaries more vulnerable to the deleterious effects of reactive oxygen species (ROS). However, antioxidant enzymes (AOEs) such as manganese-superoxide dismutase (Mn-SOD), copper,zinc-superoxide dismutase (Cu,Zn-SOD) and glutathione peroxidase (GPx1) protect cells against the biological damage of ROS-induced OS and support cancer prevention by maintaining normal cell cycle progression, inhibiting proliferation, tumor invasion, angiogenesis, inflammation or inducing apoptosis. In the present study, we aimed to measure the levels of trace elements [manganese (Mn), copper (Cu), zinc (Zn) and selenium (Se)] which are structurally and/or functionally associated with the AOEs by inductively coupled plasma/mass-spectrometry (ICP/MS) in blood samples of patients with EOC (M, n = 26) and compare the data with healthy subjects (C, n = 46). Serous EOC (M1, n = 18) data were also evaluated according to the tumor grading [well or moderately well differentiated (G 1-2) vs. poorly differentiated or undifferentiated (G3)] and staging of disease [stage I-II (SI-II) vs. stage III (SIII)]. We obtained; i) The Mn and Se levels of M were significantly lower than C, ii) only Mn levels were changed [(G3_(Mn) < G 1-2 _(Mn)] in M1, iii) significant correlations were observed between [Cu and Zn levels (r = 0.701, p = 0.036) in G 1-2 and (r = 0.686, p = 0.041) in G3; Cu and Se levels (r = 0.960, p = 0.000) in G3; Mn levels and Mn-SOD expression (r = 0.551, p = 0.006) in M, (r = 0.857, p = 0.007) in G 1-2 and (r = 0.690, p = 0.056) in G3; Se levels and erythrocyte GPx1 activity (r = 0.660, p = 0.053) in G 1-2 ; Se levels and erythrocyte Cu,Zn-SOD activity (r = 0.693, p = 0.038) in G3]. The study revealed that trace elements, particularly low Mn and Se levels along with high Cu/Se ratios might be of value in all histologic subtypes of EOC. Although Mn level was important in terms of discriminating tumor grades, positive correlation between Cu-Se levels was also remarkable in patients with G 1-2 tumors of M1. Moreover, high erythrocyte Cu/Se ratios might be a favourable marker for EOC.

Assessment of oxidant-antioxidant status alterations with tumor biomarkers and reproductive system hormones in uterine MYOMAS

OBJECTIVES

Uterine myomas (UM) are responsible for significant morbidity and have adverse effects on quality of life in women. Reactive oxygen species (ROS) and antioxidant enzymes (AOE), as well as sex steroids play important roles in the reproductive physiology processes. Thus, we aimed to investigate the role of oxidant-antioxidant status in UM by measuring the AOE activities and lipid peroxidation (LPO) levels. This is the first study assessing these parameters together in UM based on also menopausal status and evaluating possible correlations between AOE activities, LPO markers, tumor biomarkers, female reproductive system hormone levels, comprehensively.

STUDY DESIGN

The study group consisted of patients who have undergone surgical resection with confirmed pathology of uterine myoma (UM, n = 25) and divided into subgroups; premenopausal (UM_pre) and postmenopausal (UM_post). Erythrocyte copper-zinc superoxide dismutase (Cu,Zn-SOD), catalase (CAT), glutathione peroxidase (GPx1) activities were measured along with plasma malondialdehyde (MDA) and urinary 8-epi-prostaglandin F2α (8-epi-PGF2α) levels in patients with UM. The obtained data were compared to the data of healthy individuals (C, n = 25) and its subgroups; premenopausal (C_pre) and postmenopausal (C_post).

RESULTS

All AOE activities were higher (∼40% for Cu,Zn-SOD, p = 0.003; ∼55% for CAT, p = 0.001; ∼15% for GPx1, p = 0.169) and the LPO levels were lower (∼60% for MDA, p = 0.011 and ∼45% for 8-epi-PGF2α, p = 0.055) in patients with UM vs control. Approximately similar alterations were observed in UM_pre vs C_pre and in UM_post vs C_post. A significant negative correlation between erythrocyte Cu,Zn-SOD activity and plasma MDA levels (r = -0.431, p = 0.005) was reported.

CONCLUSION

Decreased LPO levels might be the consequence of compensator high antioxidant enzyme activities against mild oxidative stress in the circulation of patients with UM. The marked negative correlation between erythrocyte Cu,Zn-SOD activity and plasma MDA levels also supported this finding.

Impaired antioxidant enzyme functions with increased lipid peroxidation in epithelial ovarian cancer

We aimed to identify the possible role of oxidant-antioxidant status in epithelial ovarian cancer (EOC) by measuring (a) antioxidant enzyme (AOE) activities [total superoxide dismutase (SOD_total ), manganese-SOD (Mn-SOD), copper,zinc-SOD (Cu,Zn-SOD), catalase (CAT) and glutathione peroxidase (GPx1)], (b) Mn-SOD protein expression, (c) lipid peroxidation markers [malondialdehyde (MDA), 8-epi-prostaglandin-F2α (8-epi-PGF2α)] and by evaluating the possible correlations between tumor biomarkers, reproductive hormone levels and all measured parameters, comprehensively. The data obtained from the patients with EOC (M, n = 26) evaluated according to the histopathological/clinical characteristics of tumors and compared with data of healthy controls [C_tissue (C1) and C_blood/urine (C2), n = 30, respectively). Significantly, low activities of tumor SOD_total (52%), Mn-SOD (42%), Cu,Zn-SOD (55%); high activities of tumor and erythrocyte CAT (66%, 33% respectively) and tumor GPx1 (60%); high levels of tumor Mn-SOD protein expression; tumor MDA (193%) and urinary 8-epi-PGF2α (179%) were observed in serous EOC tumors (M1, n = 18) compared with controls (P < 0.05). However, higher levels of tumor MDA, Mn-SOD protein expression and urinary 8-epi-PGF2α were observed along with lower tumor CAT activity in poorly differentiated or undifferentiated (grade 3, G 3) versus well or moderately well differentiated (grade 1-2, G 1-2) serous EOC tumors. Obtained data indicate the presence of a severe redox imbalance in EOC and draw attention to the criticial role of AOEs in the pathogenesis of the disease. © 2017 IUBMB Life, 69(10):802-813, 2017.

The effects of fenvalerate on hepatic and cerebral xenobiotic metabolizing enzymes in selenium and/or iodine deficient rats

OBJECTIVES

Particularly in developing countries, selenium and/or iodine deficiencies are encountered and use of pesticides in agriculture are not well-controlled. Fenvalerate is a pyrethroid insectide used in agriculture and has applications against a wide range of pests. This study was designed to evaluate the effects of fenvalerate on hepatic and cerebral xenobiotic metabolizing enzyme activities in the presence of iodine and/or selenium deficiency on a rat model.

MATERIALS AND METHODS

Iodine and/or selenium deficiency was induced by feeding three-week-old Wistar rats with a diet containing <0.005 mg selenium kg-1, and/or administering 1% sodium perchlorate in drinking water for 7 weeks. Test groups received fenvalerate (100 mg kg-1 BW IP) for the last 7 days. Hepatic and cerebral microsomal aniline hydroxylase (CYP2E1) and cytosolic glutathione S-transferase (GST) activities were determined. Besides, hepatic NADPH-cytochrome P450 reductase (P450R), ethoxyresorufin O-deethylase (EROD, CYP1A1/1A2) and penthoxyresorufin O-depenthylase (PROD, CYP2B1/2B2), activities were also measured.

RESULTS

Fenvalerate had a general inductive effect on the hepatic and cerebral xenobiotic metabolizing enzyme activities. Moreover, enzyme activities were also altered by iodine and/or selenium deficiency, but the effects seemed to be enzyme- and tissue-specific.

CONCLUSION

The inductive effect of fenvalerate, particularly in high dose exposures, may change the metabolism of several xenobiotics, including drugs, as well as endogenous substrates. The effects may vary depending on the selenium and/or iodine status of individual.

The ameliorating effects of vitamin E on hepatic antioxidant system and xenobiotic-metabolizing enzymes in fenvalerate-exposed iodine-deficient rats

This study investigated the effects of vitamin E (VE) on hepatic antioxidant system and drug-metabolizing enzymes in fenvalerate (FEN)-exposed iodine-deficient (ID) Wistar rats. ID was produced by perchlorate containing drinking water. VE was introduced by a loading dose of 100 mg/kg/d, i.g. for the first three days in the last week of feeding period; then with a single maintenance dose of 40 mg/kg on the 4th day. During last week, FEN groups (F) received 100 mg/kg/d, i.p. FEN. VE alone did not significantly affect thyroid hormones and antioxidant parameters; however, significantly increased total cytochrome P450 (38%) and cytochrome b5 levels (36%). In all ID groups, plasma thyroid-stimulating hormone (TSH) levels increased markedly, but remained at control level in vitamin E plus FEN receiving iodine-deficient group (IDVF) group. Glutathione peroxidase activity showed marked increases in F (19%) and FEN-exposed iodine-deficient group (IDF, 48%) groups. FEN treatment significantly increased total cytochrome P450 (28%) and thiobarbituric acid reactive substance levels (36%), as well as 7-ethoxyresorufin O-deethylase (120%), 7-penthoxyresorufin O-deethylase (139%) and glutathione S-transferase (15%) activities and decreased total glutathione concentrations (28%) versus control. Overall results suggest that vitamin E has ameliorating effects on the measured parameters in ID and/or FEN exposure.

Selenium and/or iodine deficiency alters hepatic xenobiotic metabolizing enzyme activities in rats

The objective of this study was to investigate the effects of iodine (I(2)) and/or selenium (Se) deficiency on thyroid hormones and hepatic xenobiotic metabolizing enzyme systems using a triple animal model. Three-week-old male Wistar rats were fed for seven weeks. Se deficiency was introduced by a diet containing <0.005 mg/kg Se, and I(2) deficiency was produced by sodium perchlorate containing drinking water. The levels of plasma thyroid hormones [total T(4) (TT(4)), total T(3) (TT(3))], thyroid stimulating hormone (TSH); total microsomal cytochrome P450 (CYP450) and cytochrome b5 (CYP b5) levels; activities of microsomal NADPH-cytochrome P450 reductase (P450R), microsomal aniline hydroxylase (CYP2E1), microsomal 7-ethoxyresorufin O-deethylase (EROD), microsomal 7-pentoxyresorufin O-depentylase (PROD) and cytosolic glutathione S-transferase (GST) were determined. In I(2) deficiency total CYP450 levels, activities of CYP2E1, EROD and GST decreased, and CYP b5 content increased significantly. In Se-deficient rats, total CYP450 level and CYP2E1 activity increased, and EROD and GST activities and CYP b5 level decreased significantly. In combined I(2) and Se deficiency, except for CYP450 content and CYP2E1 activity, all enzyme activities and CYP b5 content decreased significantly compared to control group. Overall results of this study have suggested that metabolism of xenobiotics as well as endogenous compounds is affected by Se and I(2) status.