The effects of re-irradiation on the chemical and morphological properties of permanent teeth.

This study aimed to assess the in vitro effects of re-irradiation on enamel and dentin properties, simulating head and neck cancer radiotherapy retreatment. Forty-five human permanent molars were classified into five groups: non-irradiated; irradiated 60 Gy, and re-irradiated with doses of 30, 40, and 50 Gy. Raman spectroscopy, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS) were employed for analysis. Raman spectroscopy assessed intensity, spectral area, and specific peaks comparatively. Statistical analysis involved Kolmogorov-Smirnov and One-Way ANOVA tests, with Tukey's post-test (significance level set at 5%). Significant changes in irradiated, non-irradiated, and re-irradiated enamel peaks were observed, including phosphate (438 nm), hydroxyapatite (582 nm), phosphate (960 nm), and carbonate (1070 nm) (p < 0.05). Re-irradiation affected the entire tooth (p > 0.05), leading to interprismatic region degradation, enamel prism destruction, and hydroxyapatite crystal damage. Dentin exhibited tubule obliteration, crack formation, and progressive collagen fiber fragmentation. EDX revealed increased oxygen percentage and decreased phosphorus and calcium post-reirradiation. It is concluded that chemical and morphological changes in irradiated permanent teeth were dose-dependent, exacerbated by re-irradiation, causing substantial damage in enamel and dentin.

Single Nucleotide Polymorphisms as Biomarker Predictors of Oral Mucositis Severity in Head and Neck Cancer Patients Submitted to Combined Radiation Therapy and Chemotherapy: A Systematic Review.

Single Nucleotide Polymorphisms (SNPs) are the most common type of genetic variation found in an individual's DNA sequences. SNPs can occur in both coding and non-coding regions of the genome and can affect gene expression, protein function, and disease susceptibility. In this systematic review, we evaluate the potential of SNPs as biomarkers in the assessment of oral mucositis (OM) severity in head and neck cancer (HNC) patients treated with concomitant chemoradiation (CRT). The study selection process involved screening 66 articles from different platforms, and after removing duplicates and excluding articles that did not meet the eligibility criteria, 23 articles were included for full-text evaluation. Among them, genes from several pathways were analyzed. The DNA damage repair pathways had the highest number of genes studied. The most frequently analyzed gene was XRCC1. The proinflammatory cytokine pathways evaluated were TNF, with three articles, and NF-κB, with one article. Most included studies showed a potential association between certain SNPs and high-grade mucositis. We conclude that SNPs can be used as possible biomarkers for the assessment of OM intensity in HNC patients, and further research is needed to explore the potential of SNPs in personalized medicine for HNC treatment.

Color stability and microhardness alteration of irradiated dental enamel treated with a high fluoride concentration toothpaste.

OBJECTIVES: Radiotherapy (RT) is a kind of head and neck cancer (HNC) treatment, which is associated to the habit of smoking and can develop collateral effects in the oral cavity, such as the increase of caries prevalence. This study evaluated the color alteration, the microhardness, and the remineralizing potential of high fluoride concentration toothpastes on irradiated teeth. MATERIALS AND METHODS: Forty bovine teeth were used (6 × 6 × 2 mm) and after color (EasyShade, VITA) and microhardness initial readings were separated into two groups: exposed to cigarette smoke and non-exposed. All samples were submitted to RT (30 Gy) and to cariogenic challenge. New color and microhardness readings were done. After RT (60 Gy), the samples were submitted to simulated toothbrushing (73,000 cycles = 5 years of brushing) with two different toothpastes: conventional (1450 ppm) and high fluoride concentration (5000 ppm). Final color and microhardness readings were done after brushing. Data were analyzed with 2-way ANOVA with repeated measures and Tukey's test (p < .05). RESULTS: There was no color difference after RT, nor after brushing (p > .05). However, after brushing, microhardness values increased for the samples treated with high fluoride concentration toothpaste (p < .05). CONCLUSION: Radiotherapy did not influence the teeth color, and the high fluoride concentration toothpaste presented remineralizing potential; therefore, it could be used on the caries prevention related to HNC radiation. CLINICAL RELEVANCE: Considering its remineralizing potential, toothpastes with high fluoride concentration could be a proper alternative for caries prevention in patients undergoing radiotherapy.

Pelvic floor muscles after prostate radiation therapy: morpho-functional assessment by magnetic resonance imaging, surface electromyography and digital anal palpation.

AIM: To evaluate the radiotherapy (RT) effect in the pelvic floor muscles (PFM) function in men with prostate cancer (PC). MATERIALS AND METHODS: A cross-sectional study included three groups of patients with PC and RT indication: 1) Pre-RT group: evaluated before the beginning of RT; 2) Acute group: evaluated between six months and one year after RT; 3) Late Group: evaluated between two and a half years and four years post-RT. PFM assessment was divided into: a) functional assessment through the digital anal palpation (Modified Oxford Scale) and surface electromyography (sEMG) with anal probe; b) anatomical assessment by pelvic magnetic resonance imaging (MRI) with thickness measurements of levator ani muscle and pelvic specific parameters at rest and under Valsalva maneuver. We used Student t test, considering as significant p <0.05. RESULTS: Thirty-three men were assessed: Pre-RT (n=12); Acute (n=10) and Late (n=11) groups. PFM functional assessment showed Late group with lower electromyographic activity, especially in the sustained contractions when compared to the Pre-RT (p=0.003) and Acute groups (p=0.006). There was no significant difference between groups in MRI. CONCLUSION: PFM functional assessment showed a decrease in sEMG activity in the Late group post-RT. Most of the sample (72.7%) did not know how to actively contract the PFM or had a weak voluntary contraction when assessed by digital anal palpation. Also, these patients presented higher prevalence of pelvic complaints. No changes were observed in the morpho-functional parameters evaluated by MRI, except the measurement of the membranous urethra length when comparing Pre-RT Group and Acute and Late Groups.

Radiotherapy Impairs Adhesive Bonding in Primary Teeth: An In Vitro Study.

Purpose: To evaluate the morphological alterations in enamel and dentin of primary teeth following radiotherapy (RT) and to determine the best adhesive technique and time to carry out restorative procedures.
Methods: Enamel and dentin fragments of primary teeth were randomly assigned into four groups (n=30): G1 (control)-non-irradiated, only restorative procedure; G2- restorative procedure immediately before RT; G3-restorative procedure 24 hours after RT; and G4-restorative procedure six months after RT. Each group was divided into one of two subgroups according to the adhesive system used for restoration: (1) AdperSingle Bond 2 (SB); and (2) ClearfillSE Bond (CL). The specimens were submitted to fractionated RT until they reached the final dose of 60 Gy. They were then subjected to confocal microscopy and the shear bond strength test. Data were analyzed using two-way analysis of variance followed by Tukey's tests ( α = five percent).
Results: Morphological changes were first observed in enamel and dentin after 40 Gy of irradiation. G4 bond strength values were similar to G1 in the CL and SB groups for enamel and in the CL group for dentin (P >0.05). G2 showed the lowest values for enamel and dentin (P <0.05). In G3, CL presented the highest strength values in enamel; for G4, the highest values were found in dentin (P <0.05).
Conclusions: Radiotherapy affected the morphological surface of enamel and dentin. The restorations placed immediately after RT had the weakest shear bond strength, and the restorations placed six months after RT had similar means of bond strength compared to the nonirradiated teeth in enamel, regardless of the adhesive system used. In dentin, CL showed better performance than SB.

Topical pilocarpine for xerostomia in patients with head and neck cancer treated with radiotherapy.

OBJECTIVE: To evaluate a pilocarpine spray as a treatment for xerostomia in patients treated with radiotherapy (RT) for head and neck cancer (HNC). METHODS: This was a placebo-controlled, double-blind, crossover clinical trial of patients complaining of dry mouth after RT for HNC. Forty patients were randomly assigned to either placebo or pilocarpine (1.54%) spray and instructed to use three times a day for 3 months. After 1-month washout period, patients were crossed over to receive placebo or pilocarpine. The assessments were salivary flow (Stimulated Whole Saliva Flow - SWSF), xerostomia (Xerostomia Inventory - XI), and quality of life (QoL/Oral Health Impact Profile - OHIP-14), assessed at baseline, 1 hr (only SWSF), and at 1, 2, and 3 months of treatment. RESULTS: Posttreatment SWFS was not statistically different between pilocarpine and placebo regardless of the treatment sequence (paired T test; p > .05), except for the SWFS rates at 2 months after therapy. When comparing pilocarpine with placebo in the time points, there was no significant difference (p > .05) for QoL or XI. Significant differences in improvement in QoL and xerostomia experience appeared along time for pilocarpine group. CONCLUSION: The topical application of pilocarpine spray tested was similar to placebo on SWSF assessments in patients treated with RT for HNC.

Intercessory Prayer on Spiritual Distress, Spiritual Coping, Anxiety, Depression and Salivary Amylase in Breast Cancer Patients During Radiotherapy: Randomized Clinical Trial.

The goal of this study was to assess the effect of intercessory prayer in the psychological, spiritual and biological scores of breast cancer patients who are undergoing radiotherapy. Double-blind RCT comprising a sample of 31 participants (15 in the Control Group and 16 in the Intervention Group). Data collection was performed in three time points (T0, T1 and T2). Significant changes have been identified in the intra-group analysis, concerning the decrease in spiritual distress score; negative religious/spiritual coping prevailed, while the total religious/spiritual coping increased between the posttest T2 to T0. Intercessory prayer was effective in religious and spiritual scores.

Radiotherapy impairs adhesive bonding in permanent teeth.

OBJECTIVES: To evaluate the in vitro effects of radiotherapy (RT) on the morphological surface of the enamel and dentin and to determine the best adhesive system and most appropriate time to restore teeth in head and neck cancer patients. METHODS: Sixty third molars were cut into 120 enamel fragments and 120 dentin fragments and divided into four groups (n = 30): G1 (control): nonirradiated, only restorative procedure; G2: restorative procedure immediately before RT; G3: restorative procedure immediately after RT; and G4: restorative procedure 6 months after RT. Each group was divided into two subgroups: Adper™ Single Bond 2 (SB) and Clearfill SE Bond (CL) based on the material used. After RT and restorative procedures, the specimens were subjected to confocal microscopy and shear bond strength test. Data were analyzed using a two-way ANOVA followed by Tukey's test at a significance level of 5%. RESULTS: Morphological changes were observed in both substrates after a cumulative dose of 40 Gy, and after 60 Gy, the changes were more evident in both substrates. CL had the highest strength values in both substrates (p < 0.05), and G2 had the lowest strength values for the enamel and dentin (p < 0.05). CONCLUSIONS: Based on the in vitro study results, we can conclude that RT substantially changes the morphological surface of enamel and dentin and impairs the bond strength. The Clearfill system yielded better results than Adper Single Bond 2, and restoring teeth before RT resulted in the worst results in both substrates.

Standardization of a resazurin-based assay for the evaluation of metabolic activity in oral squamous carcinoma and glioblastoma cells.

The widely accepted resazurin-based assay can be used, prior to in vivo studies, as an inexpensive method to determine cytotoxicity. The aim of this study was to evaluate and standardize the assay conditions for oral squamous cancer cell (OSCC) and glioblastoma (U87-MG) lines by UV-vis spectroscopy. The cells were treated with 25 µgmL-1 of resazurin sodium salt and then incubated for 4 h, 6 h, and 6.5 h. All absorbance measurements were carried out at 21 ± 1 °C on a spectrophotometer with a microplate reader. After 4-hs of incubation, resazurin was completely reduced by OSCC cells, as demonstrated by the suppression of the absorbance at 380 nm. However, the U87-MG cells needed 6.5 h of incubation to demonstrate the same behavior. The Statistical analysis did not indicate significant differences between the OSCC and U87-MG cell lines' viability after 4 and 6.5 h respectively. We concluded that spectroscopic analysis is an efficient method for the standardization of the resazurin assay. In addition, without the implementation of suitable protocols, there could be an increase in the chance of errors or false positives or negatives that would reduce the usefulness of the data.

Survival after radiation therapy for high-grade glioma.

BACKGROUND: High-grade gliomas (HGGs) are a heterogeneous disease group, with variable prognosis, inevitably causing deterioration of the quality of life. The estimated 2-year overall survival is 20%, despite the best trimodality treatment consisting of surgery, chemotherapy, and radiotherapy. AIM: To evaluate long-term survival outcomes and factors influencing the survival of patients with high-grade gliomas treated with radiotherapy. MATERIALS AND METHODS: Data from 47 patients diagnosed with high-grade gliomas between 2009 and 2014 and treated with three-dimensional radiotherapy (3DRT) or intensity-modulated radiotherapy (IMRT) were analyzed retrospectively. RESULTS: Median survival was 16.6 months; 29 patients (62%) died before the time of analysis. IMRT was employed in 68% of cases. The mean duration of radiotherapy was 56 days, and the mean delay to the start of radiotherapy was 61.7 days (range, 27-123 days). There were no statistically significant effects of duration of radiotherapy or delay to the start of radiotherapy on patient outcomes. CONCLUSIONS: Age, total amount of gross resection, histological type, and use of adjuvant temozolomide influenced survival rate (p < 0.05). The estimated overall survival was 18 months (Kaplan-Meier estimator). Our results corroborated those reported in the literature.

Effect of radiotherapy on the chemical composition of root dentin.

BACKGROUND: The radiotherapy can directly affect the bond strength of the adhesive materials, interfering in the prognosis of restorative treatments, which may be caused by chemical changes in dentin structure. METHODS: Twenty inferior homologues premolars were distributed in 2 groups (in vitro study) (n = 10): nonirradiated and irradiated. The specimens were submitted to the analysis of phosphate (ν1 PO43- ;ν2 PO43- ;ν4 PO43- ), carbonate (ν3 CO32- ), amide I, CH2 , amide III, and amide I/III ratio by confocal Raman spectroscopy. Data were submitted to statistical analysis (T test, P < .05). RESULTS: In intracanal dentin, the irradiated group had lower ν4 PO43- values (1.23 ± 0.06) compared to nonirradiated group (1.40 ± 0.18) (P < .05), with no difference for ν1 PO43- and ν2 PO43 peaks (P > .05). The irradiated (1.56 ± 0.06) had lower carbonate, amide III (1.05 ± 0.19), and amide I/III ratio values (0.19 ± 0.06) compared to nonirradiated group (1.42 ± 0.10, 1.28 ± 0.24, and 0.31 ± 0.10, respectively) (P < .05). For medium dentin irradiated group (1.30 ± 0.12) had lower phosphate values compared to nonirradiated group (1.48 ± 0.22) (P < .05). In cementum, there was no statistical difference between the groups. CONCLUSION: The radiotherapy was able to cause changes in ν4 PO43- , carbonate, and amide III peaks of root dentin.

DTCM-glutarimide Delays Growth and Radiosensitizes Glioblastoma.

BACKGROUND AND PURPOSE: Glioblastoma (GBM) is the most aggressive brain tumor. Even with the advent of temozolomide, patient survival remains poor, with expected median survival around 1 year from diagnosis. Consequently, the relentless search for new therapeutic strategies able to increase patient outcome persists. 3-[(dodecylthiocarbonyl) methyl] glutarimide (DTCM-g) is a new anti-inflammatory compound that already showed antitumor effects. MATERIALS AND METHODS: Clonogenic survival, proliferation, apoptosis, cell cycle progression and invasion capacity of pediatric and adult GBM cell lines (U87MG, U251MG, SF188 and KNS-42) were evaluated under treatment with DTCM-g. The combined treatment with radiation was also evaluated in vitro and in vivo through xerographic models. RESULTS: DTCM-g is able to impair proliferation, reduce clonogenic capacity and induce cell cycle arrest in GBM cell lines. No alteration in apoptosis rates was found after treatment. DTCM-g also reduces the invasion capacity of all GBM cell lines without alterations in MMP2 and uPa expression. Moreover, the drug radiosensitized GBM in vitro and in vivo. CONCLUSION: Although additional studies are still necessary to support our findings, our results suggest that DTCM-g may be a promising drug on the adjuvant treatment of GBM exhibiting antitumor effects, especially through radiosensitization.

Effects of the Metallic Port in Tissue Expanders on Dose Distribution in Postmastectomy Radiotherapy: A Tridimensional Experimental Model of Dosimetry in Breast Reconstruction.

The purpose of this research was to develop an experimental model of dosimetry using a breast phantom and evaluate the effects of the metallic port in tissue expanders on dose distribution in postmastectomy radiotherapy. Dose distribution was assessed using an experimental acrylic dosimetry simulator in the absence and presence of a metallic disc (MD), which is similar to that used in tissue expanders containing a magnetic port, by collecting coronal and sagittal radiochromic films. Dosimetry film analysis did not show any changes in dose distribution, except for a MD shadow in the sagittal film where the dose distribution rate was on average 14% lower than in other areas. This model very closely resembled actual breast reconstruction with a tissue expander containing a magnetic port. Scattering or attenuation of the irradiation dose due to interference of the MD was not evident in areas that could jeopardize the effectiveness of radiation therapy. Therefore, the presence of the MD inside the tissue expander does not likely have an impact on radiotherapy effectiveness during immediate breast reconstruction.

KRAS mutation associated with CD44/CD166 immunoexpression as predictors of worse outcome in metastatic colon cancer.

INTRODUCTION: Multiple stages of carcinogenesis in colon cancer encompass subpopulations of cancer stem cells (CSC), responsible for tumor cell transformation, growth and proliferation. CD44 and CD166 proteins are CSC markers associated with cell signaling, adhesion, migration, metastasis and lymphocytic response. The expression of CSC may be modulated by some factors, such as the KRAS gene mutation. OBJECTIVE: Correlate the expression of CD44 and CD166 markers in metastatic colon adenocarcinoma and KRAS mutation status (wild-type/mutated) with clinical pathological features and patients' outcome. MATERIAL AND METHODS: Fifty-eight samples of tumor tissue samples of metastatic colon adenocarcinoma were collected from patients treated with CapeOx at the HCFMRP-USP Clinical Oncology Service. Clinical and survival data were collected from medical records. KRAS status was determined by the polymerase chain reaction (PCR) technique, and analysis of immunohistochemical expression of CD44 and CD166 proteins was performed by tissue microarray. RESULTS: The expression of CD44 and CD166 were positive in 41% and 43% of patients, respectively, and mutated KRAS was detected in 48% of patients. A significant association was found between CD166 and CD44 expression (p= 0.016), mainly in the wild-type KRAS group (p= 0.042) and patients over 65 years (p= 0.001). CD44-positive patients had 3.7-fold and 5.3-fold greater risk of liver metastasis and lung metastasis, respectively (p< 0.01), compared with CD44-negative patients. CD166-negative patients had 2.7 greater risk of lymph node involvement (0.03), compared with CD166-positive patients. KRAS mutation increased the risk of liver metastasis by 8 times (p< 0.01), and the risk of lung metastasis by 5 times (p= 0.04) in CD44-positive patients. KRAS mutation increased the risk of lymph node involvement by 8 times in CD166-negative patients (p= 0.0007). CONCLUSION: An association between CD44 and CD166 expression was demonstrated in this study. Analysis of KRAS mutation combined with immunohistochemical expression of CD44 and CD166 identified subgroups of patients with colon adenocarcinoma at higher risk of lymph node involvement by the tumor and development of liver and lung metastasis.

Physical and adhesive properties of dental enamel after radiotherapy and bonding of metal and ceramic brackets.

INTRODUCTION: The increasing success rates for cancer patients treated with radiotherapy and the frequent occurrence of tooth loss during treatment have led to an increased demand for orthodontic treatment after radiotherapy. The aim of this study was to evaluate tooth enamel of irradiated teeth after the bonding and debonding of metal and ceramic brackets. METHODS: Ten permanent molars were cut into enamel fragments measuring 1 mm(2) and divided into an irradiated group (total dose of 60 Gy) and a nonirradiated group. The fragments were subjected to microshear testing to evaluate whether radiotherapy altered the strength of the enamel. Furthermore, 90 prepared premolars were divided into 6 groups and subgroups (n = 15): group 1, nonirradiated and nonaged; group 2, nonirradiated and aged (thermal cycled); group 3, irradiated and aged; each group was divided into 2 subgroups: metallic and ceramic brackets. After thermal cycling and radiotherapy, the brackets were bonded onto the specimens with Transbond XT (3M Unitek, Monrovia, Calif). After 24 hours, the specimens were subjected to the shear tests. Images of the enamel surfaces were classified using the adhesive remnant index. The composite resin-enamel interface was also evaluated. RESULTS: Enamel fragments subjected to radiation had lower strength than did the nonirradiated samples (P <0.05). The groups and subgroups submitted to radiation and bonded ceramic brackets had the lowest strength values. Groups 1 and 2 with metallic brackets had less adhesive on the surface, whereas groups 1 and 2 with ceramic brackets and group 3 with both metallic and ceramic brackets had more adhesive on the surfaces. On the images of the composite resin-enamel interface, resin tags were more extensive on irradiated tooth enamel. CONCLUSIONS: Radiation decreased tooth enamel strength, and the specimens treated with radiotherapy had higher frequencies of adhesive failure between the bracket and the composite resin as well as more extensive tags.

The effect of radiation therapy on the mechanical and morphological properties of the enamel and dentin of deciduous teeth--an in vitro study.

PURPOSE: To evaluate the effects of radiation therapy on deciduous teeth. MATERIALS AND METHODS: The enamel and dentin microhardness (n = 12) was evaluated at 3 depths, both before (control) and after each 10 Gy of irradiation and up to a dose of 60 Gy. The morphology was evaluated via scanning electron microscopy (SEM) (n = 8). The data were analyzed using a two-way analysis of variance (ANOVA) and Tukey's test (α = 5%). RESULTS: The enamel microhardness, as a whole, increased (p < 0.05) after a dose of 60 Gy (211.4 KH), mostly in the superficial enamel. There was a significant difference between the values of nonirradiated dentin microhardness (28.9 KH) compared with dentin that was irradiated with doses of 10 Gy (23.8 KH), 20 Gy (25.6 KH), 30 Gy (24.8 KH), and 40 Gy (25.7 KH) (p < 0.05). There was no difference between nonirradiated dentin and dentin irradiated with 60 Gy (p > 0.05). The highest mean value of microhardness (29.9 KH) (p < 0.05) was found in the middle dentin. The groups that were irradiated with doses of 30 and 60 Gy exhibited greater surface changes in their enamel and dentin compared with the nonirradiated groups for all regions, exhibiting an amorphous surface upon increase of the irradiation doses. CONCLUSIONS: The enamel microhardness increased at a dose of 60 Gy, whereas the value of the dentin microhardness did not change. A progressive disruption of enamel and dentin morphology was found with the increased radiation dose.

Intensity modulated radiotherapy (IMRT) for patients of the Brazilian unified health system (SUS): an analysis of 508 treatments two years after the technique implementation.

The Bosniak classification for renal cysts was developed in the late 1980s in an attempt to standardize the description and management of complex cystic renal lesions. Alterations were made to such a classification in the 1990s and, the last one, in 2005. Currently, five categories of cystic renal lesions are defined - namely, I, II, II-F, III and IV -, according to their degree of complexity and likelihood of malignancy. Despite being initially described for computed tomography, this classification has been also utilized with some advantages also for magnetic resonance imaging. The present article reviews the different phases of this classification, its diagnostic efficacy and the most controversial features of its use.

OBJETIVO: A oferta de radioterapia de alta tecnologia para população atendida pelo Sistema Único de Saúde (SUS) é limitada, por não pertencer ao rol de procedimentos e, muitas vezes, pela capacidade instalada frente à demanda e dificuldade de retenção de recursos humanos especializados. Dessa forma, o acesso à radioterapia de intensidade modulada (IMRT) é restrito a poucos serviços no Brasil. Pretendemos apresentar as características dos primeiros 508 tratamentos de IMRT durante os primeiros anos de instalação da técnica em um hospital universitário. MATERIAIS E MÉTODOS: Foram analisados 508 tratamentos de IMRT, de maio de 2011 a setembro de 2013, que completaram a radioterapia. A técnica empregada foi multilâminas estático. RESULTADOS: De um total de 4.233 pacientes tratados no período, 12,5% realizaram IMRT. As principais indicações foram para crânio, cabeça e pescoço, e próstata. Aproximadamente 30% das radioterapias de crânio e 50% das de próstata foram por IMRT. A toxicidade total foi 4%. CONCLUSÃO: Em razão das restrições de acesso à radioterapia e da não cobertura deste procedimento, as indicações de IMRT para pacientes do SUS devem ser apoiadas nos protocolos clínicos das instituições em acordo com sua realidade, com especial atenção à redução da toxicidade.

BUB1 and BUBR1 inhibition decreases proliferation and colony formation, and enhances radiation sensitivity in pediatric glioblastoma cells.

PURPOSE: Glioblastoma (GBM) is a very aggressive and lethal brain tumor with poor prognosis. Despite new treatment strategies, patients' median survival is still lower than 1 year in most cases. The expression of the BUB gene family has demonstrated to be altered in a variety of solid tumors, pointing to a role as putative therapeutic target. The purpose of this study was to determine BUB1, BUB3, and BUBR1 gene expression profiles in glioblastoma and to analyze the effects of BUB1 and BUBR1 inhibition combined or not with Temozolomide and radiation in the pediatric SF188 GBM cell line. METHODS: For gene expression analysis, 8 cell lines and 18 tumor samples were used. The effect of BUB1 and BUBR1 inhibition was evaluated using siRNA. Apoptosis, cell proliferation, cell cycle kinetics, micronuclei formation, and clonogenic capacity were analyzed after BUB1 and BUBR1 inhibition. Additionally, combinatorial effects of gene inhibition and radiation or Temozolomide (TMZ) treatment were evaluated through proliferation and clonogenic capacity assays. RESULTS: We report the upregulation of BUB1 and BUBR1 expression and the downregulation of BUB3 in GBM samples and cell lines when compared to white matter samples (p < 0.05). Decreased cell proliferation and colony formation after BUB1 and BUBR1 inhibition were observed, along with increased micronuclei formation. Combinations with TMZ also caused cell cycle arrest and increased apoptosis. Moreover, our results demonstrate that BUB1 and BUBR1 inhibition sensitized SF188 cells to γ-irradiation as shown by decreased growth and abrogation of colony formation capacity. CONCLUSION: BUB1 and BUBR1 inhibition decreases proliferation and shows radiosensitizing effects on pediatric GBM cells, which could improve treatment strategies for this devastating tumor. Collectively, these findings highlight the potentials of BUB1 and BUBR1 as putative therapeutic targets for glioblastoma treatment.

Inhibition of polo-like kinase 1 induces cell cycle arrest and sensitizes glioblastoma cells to ionizing radiation.

Despite efforts to improve surgical, radiologic, and chemotherapeutic strategies, the outcome of patients with glioblastoma (GBM) is still poor. Polo-like kinase 1 (PLK1) is a serine/threonine kinase that plays key roles in cell cycle control and has been associated with tumor growth and prognosis. Here, we aimed at testing the radiosensitizing effects of the PLK1 inhibitor BI 2536 on eight GBM cell lines. For cell cycle analysis, T98G, U251, U343 MG-a, LN319, SF188, U138 MG, and U87 MG cell lines were treated with 10, 50, or 100 nM of BI 2536 for 24 hours. In addition, cell cultures exposed to BI 2536 50 nM for 24 hours were irradiated with γ-rays from (60)Cobalt source at final doses of 2, 4, and 6 Gy. Combinatorial effects were evaluated through proliferation and clonogenic capacity assays. Treatment with BI 2536 caused mitotic arrest after 24 hours, and increased apoptosis in GBM cells. Moreover, our results demonstrate that pretreatment with this drug sensitized six out of seven GBM cell lines to different doses of γ-irradiation as shown by decreased growth and abrogation of colony-formation capacity. Our data suggest that PLK1 blockage has a radiosensitizing effect on GBM, which could improve treatment strategies for this devastating tumor.

Activator protein-1 inhibition by 3-[(dodecylthiocarbonyl)methyl]-glutamaride impairs invasion and radiosensitizes osteosarcoma cells in vitro.

Osteosarcoma (OS) is the most common primary malignant bone tumor. Despite advances in neoadjuvant multi-agent chemotherapy, the outcome of patients has not significantly improved in the last decades, making the search for more effective therapeutic agents imperative. In the present study, we explored the possibility of using activator protein-1 inhibition by 3-[(dodecylthiocarbonyl)methyl]-glutarimide (DTCM-g) as a new therapeutic strategy in two OS cell lines, HOS and MG-63. Our results showed that low concentrations (2.5, 5, 10, and 20 µg/mL) of the drug significantly decreased cell proliferation and clonogenic capacity, albeit it did not significantly induce cell death. DTCM-g also decreased cell invasiveness, and inhibited PDPN, MMP-2, TIMP1, and TIMP2 expressions. Moreover, our results showed that DTCM-g synergized with ionizing radiation in both cell lines while chemosensitized MG-63 cells to doxorubicin treatment. Even though additional laboratorial and preclinical tests are still needed to support our data, we demonstrate that DTCM-g inhibits growth in OS cells, increases the cytotoxicity of other commonly used agents, and may possess antimetastatic activity.