ALDH7A1 expression is associated with recurrence in patients with surgically resected non-small-cell lung carcinoma.

AIM: The purpose of this study was to describe the prognostic significance of ALDH7A1 in surgically treated non-small-cell lung carcinoma. (NSCLC). MATERIALS & METHODS: We immunohistochemically analyzed ALDH7A1 expression in surgically resected NSCLC from 89 patients using a tissue microarray. RESULTS: ALDH7A1 staining was positive in 43 patients and negative in 44 patients, with two tumor sections missing. For stage I NSCLC patients, ALDH7A1 positivity was associated with decreased recurrence-free and overall survival. Multivariate analysis demonstrated that ALDH7A1-expressing NSCLC tumors had a significantly higher incidence of lung cancer recurrence compared with patients with ALDH7A1-negative tumors, although there was no association with overall survival. CONCLUSION: For patients with NSCLC, low ALDH7A1 expression was associated with a decreased incidence of cancer recurrence. Specifically in stage I patients, negative staining for ALDH7A1 was associated with improved recurrence-free and overall survival, suggesting a predictive role in surgically treated patients.

Head and Neck Cancer Clinical Research on ClinicalTrials.gov: An Opportunity for Radiation Oncologists.

PURPOSE: Many improvements in head and neck cancer (HNC) outcomes are related to optimization of radiation therapy (RT) dose, fractionation, normal-tissue sparing, and technology. However, prior work has shown that the literature of randomized controlled trials is dominated by industry-sponsored trials that have lower rates of incorporating RT. We characterized HNC clinical trials, hypothesizing that RT-specific research questions may be relatively underrepresented among HNC randomized controlled trials. METHODS AND MATERIALS: A web query of all open interventional trials on www.ClinicalTrials.gov was performed using search terms "head and neck cancer" and specific HNC subsites. Trial details were captured including the modality used, principal investigator (PI) specialty, funding, and whether the study tested a RT-modality specific hypothesis. Chi-square testing and logistic regression were used to compare groups. RESULTS: There were 841 open HNC trials, including definitive (47.6%) and recurrent/metastatic (41.9%) populations. Most trials (71.7%) were phase I or nonrandomized phase II studies, rather than phase III or randomized phase II (28.3%). Among single-arm studies, most (79.6%) incorporated systemic therapy (ST), and fewer (25.2%) incorporated RT. Even fewer phase III and randomized phase II trials tested an RT-specific hypothesis (11.1%), compared with ST-related hypotheses (77.1%; P < .001); trials were more likely to test an RT-hypothesis if the study PI was a radiation oncologist (20.9% vs 6.0%; P < .001). Among RT trials, most early-phase studies tested novel modalities (eg, stereotactic body radiation therapy, proton therapy), whereas most later-phase studies tested dose and fractionation. RT-focused trials had low rates of federal (10.4%) or industry (2.6%) funding. CONCLUSIONS: RT-specific research hypotheses are a minority of phase II-III HNC trials, which mostly focus on incorporating ST in the definitive or recurrent/metastatic setting and have higher rates of industry funding. Radiation oncologist PI leadership and increased nonindustry funding access may ensure that RT-specific hypotheses are incorporated into trial design.

A low percentage of metastases in deep brain and temporal lobe structures.

BACKGROUND: Whole-brain radiotherapy (WBRT) in patients with brain metastases (BM) is associated with neurocognitive decline. Given its crucial role in learning and memory, efforts to mitigate this toxicity have mostly focused on sparing radiation to the hippocampus. We hypothesized that BM are not evenly distributed across the brain and that several additional areas may be avoided in WBRT based on a low risk of developing BM. METHODS: We contoured 2757 lesions in a large, single-institution database of patients with newly diagnosed BM. BM centroids were mapped onto a standard brain atlas of 55 anatomic subunits and the observed percentage of BM was compared with what would be expected based on that region's volume. A region of interest (ROI) analysis was performed in a validation cohort of patients from 2 independent institutions using equivalence and one-sample hypothesis tests. RESULTS: The brainstem and bilateral thalami, hippocampi, parahippocampal gyri, amygdala, and temporal poles had a cumulative risk of harboring a BM centroid of 4.83% in the initial cohort. This ROI was tested in 157 patients from the validation cohort and was found to have a 4.1% risk of developing BM, which was statistically equivalent between the 2 groups (P < 1 × 10-6, upper bound). CONCLUSION: Several critical brain structures are at a low risk of developing BM. A risk-adapted approach to WBRT is worthy of further investigation and may mitigate the toxicities of conventional radiation.

Adjuvant chemoradiation does not improve survival in elderly patients with high-risk resected head and neck cancer.

OBJECTIVES/HYPOTHESIS: Randomized trials have demonstrated that adjuvant chemoradiotherapy (CRT) confers an overall survival (OS) benefit over adjuvant radiation therapy (RT) alone in patients with resected head and neck squamous cell carcinoma (HNSCC) with adverse pathologic features (positive surgical margins [SM+] and/or extracapsular extension [ECE]). Whether this OS benefit exists in an elderly population remains unknown. STUDY DESIGN: Retrospective database study. METHODS: Using the National Cancer Database, we identified 1,686 elderly patients (age ≥70 years) with resected HNSCC with SM+ and/or ECE, who received adjuvant CRT (491 patients, 29%) or adjuvant RT alone (1,195 patients, 71%) between 1998 and 2011. Three-year survival rates were estimated using the Kaplan-Meier method both before and after propensity score matching (PSM). Crude and adjusted hazard ratios (HR) with 95% confidence intervals (CI) were computed using Cox regression modeling. RESULTS: Median follow-up was 23.5 and 42.8 months for all and surviving patients, respectively. Three-year OS was 50.7% and 44.4% among patients receiving adjuvant CRT and RT alone, respectively (P = .002). On multivariate analysis, there was no significant improvement in OS with adjuvant CRT relative to adjuvant RT alone (HR: 0.88, 95% CI: 0.73-1.06). Similarly, a PSM cohort showed no significant difference in the 3-year OS for patients receiving adjuvant CRT versus adjuvant RT alone (48.8% and 50.9%, respectively; P = .839). CONCLUSIONS: Although the addition of chemotherapy to adjuvant RT has been proven effective in randomized trials of patients with resected HNSCC with SM+ or ECE, it may be less efficacious in an elderly patient population treated outside of a controlled trial setting. LEVEL OF EVIDENCE: 2c. Laryngoscope, 128:831-840, 2018.

Funding Support and Principal Investigator Leadership of Oncology Clinical Trials Using Radiation Therapy.

PURPOSE: Sources of funding and principal investigator (PI) leadership for clinical trials using radiation therapy (RT) are not well characterized but are important mediators of innovation, particularly because funding for trials from the National Institutes of Health (NIH) has decreased and industry funding has increased. We sought to determine characteristics of trials using RT that are associated with industry funding, NIH funding, and radiation oncologist (RO) PI leadership. METHODS AND MATERIALS: www.ClinicalTrials.gov was queried for all open, interventional trials that administered RT. Logistic regression was used to identify associations between trial characteristics, receipt of funding type (NIH, industry, or other), and PI leadership. RESULTS: The authors identified 1469 oncology trials, of which 41% were based in the United States, 56% were based internationally, and 3% were based in the United States and internationally. Of these, 22% were RT monotherapy, 53% were bimodality (40% RT + drug, 13% RT + surgery), and 24% were trimodality. Although ROs led 60% of all trials, industry-sponsored trials were significantly less likely to have RO PIs (35% RO vs 65% non-RO PI; adjusted odds ratio [aOR], 0.45; 95% confidence interval [CI], 0.28-0.73), to fund trials that did not incorporate drug therapy (aOR, 0.19; 95% CI, 0.10-0.35), or to fund phase III trials (aOR, 0.25; 95% CI, 0.11-0.60) because industry-sponsored trials favored smaller phase I trials. NIH-funded trials were not associated with PI type and, although not statistically significant, favored larger phase III trials (unadjusted OR, 2.06; 95% CI, 0.99-4.29). ROs were less likely to lead trials incorporating drug therapy (aOR, 0.30; 95% CI, 0.22-0.41). CONCLUSIONS: ROs are less likely than other specialties to lead trials that use RT in combination with drug therapy or surgery and more likely to lead trials supported by nonindustry, non-NIH funding. This suggests a need for ROs to lead multimodality trials and to consider opportunities to interact with industry. As NIH resources decrease, alternative funding is needed to support innovation, particularly in in RT-alone trials.

Impact of total radiotherapy dose on survival for head and neck Merkel cell carcinoma after resection.

BACKGROUND: Head and neck Merkel cell carcinoma (MCC) is commonly treated with surgery and adjuvant radiotherapy (RT) for high-risk features. The optimal radiation dose is unknown. METHODS: One thousand six hundred twenty-five eligible patients with head and neck MCC were identified in the National Cancer Data Base (NCDB). Radiation dose was divided into 3 groups: 30 to <50 Gray (Gy), 50-55 Gy, and >55-70 Gy. Cox regression was used to compare overall survival (OS) between groups, accounting for age, sex, stage, surgery type, margin status, comorbidities, and use of chemotherapy. RESULTS: With a median follow-up of 33.5 months, 3-year OS was 48.9%, 70.3%, and 58.7% for 30 to <50 Gy, 50-55 Gy, and >55-70 Gy, respectively (P < .001). Compared to 50-55 Gy, doses between 30 to <50 Gy (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI] 1.17-1.99; P = .002) and >55-70 Gy (adjusted HR 1.21; 95% CI 1.0-1.46; P = .06) were associated with worse survival. CONCLUSION: Adjuvant radiation doses within 50-55 Gy may be optimal for head and neck MCC.

Long-term Outcomes After Bladder-preserving Tri-modality Therapy for Patients with Muscle-invasive Bladder Cancer: An Updated Analysis of the Massachusetts General Hospital Experience.

BACKGROUND: Tri-modality therapy (TMT) is a recognized treatment strategy for selected patients with muscle-invasive bladder cancer (MIBC). OBJECTIVE: Report long-term outcomes of patients with MIBC treated by TMT. DESIGN, SETTING, AND PARTICIPANTS: Four hundred and seventy-five patients with cT2-T4a MIBC were enrolled on protocols or treated as per protocol at the Massachusetts General Hospital between 1986 and 2013. INTERVENTION: Patients underwent transurethral resection of bladder tumor followed by concurrent radiation and chemotherapy. Patients with less than a complete response (CR) to chemoradiation or with an invasive recurrence were recommended to undergo salvage radical cystectomy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Disease-specific survival (DSS) and overall survival (OS) were calculated using the Kaplan-Meier method. RESULTS AND LIMITATIONS: Median follow-up for surviving patients was 7.21 yr. Five- and 10-yr DSS rates were 66% and 59%, respectively. Five- and 10-yr OS rates were 57% and 39%, respectively. The risk of salvage cystectomy at 5 yr was 29%. In multivariate analyses, T2 disease (OS hazard ratio [HR]: 0.57, 95% confidence interval [CI]: 0.44-0.75, DSS HR: 0.51, 95% CI: 0.36-0.73), CR to chemoradiation (OS HR: 0.61, 95% CI: 0.46-0.81, DSS HR: 0.49, 95% CI: 0.34-0.71), and presence of tumor-associated carcinoma in situ (OS HR: 1.56, 95% CI: 1.17-2.08, DSS HR: 1.50, 95% CI: 1.03-2.17) were significant predictors for OS and DSS. When evaluating our cohort over treatment eras, rates of CR improved from 66% to 88% and 5-yr DSS improved from 60% to 84% during the eras of 1986-1995 to 2005-2013, while the 5-yr risk of salvage radical cystectomy rate decreased from 42% to 16%. CONCLUSIONS: These data demonstrate high rates of CR and bladder preservation in patients receiving TMT, and confirm DSS rates similar to modern cystectomy series. Contemporary results are particularly encouraging, and therefore TMT should be discussed and offered as a treatment option for selected patients. PATIENT SUMMARY: Tri-modality therapy is an alternative to radical cystectomy for patients with muscle-invasive bladder cancer, and is associated with comparable long-term survival and high rates of bladder preservation.

Prostate-Specific Antigen Failure and Risk of Death Within Comorbidity Subgroups Among Men With Unfavorable-Risk Prostate Cancer Treated in a Randomized Trial.

Purpose Physicians sometimes make management recommendations on the basis of early results from randomized controlled trials (RCTs) relating to reduced prostate-specific antigen (PSA) failure, yet whether this early end point is associated with all-cause mortality (ACM), particularly in men with competing risks, is unknown. Using a validated metric in men treated within the context of an RCT, we aimed to determine whether PSA failure is associated with the risk of ACM stratified by comorbidity score. Patients and Methods Between 1995 and 2001, 206 men with localized (T1b to 2b) intermediate- and high-risk prostate cancer (PC) were randomly assigned to receive radiation therapy or radiation therapy and 6 months of ADT. Cox regression analyses were performed to evaluate whether PSA failure modeled as a time-dependent covariate was associated with an increased risk of ACM among men with Adult Comorbidity Evaluation-27-defined no or minimal versus moderate-to-severe comorbidity adjusting for age, PC prognostic factors, and treatment. Results After a median follow-up of 16.62 years, 156 men (76%) died, 29 of whom (19%) died as a result of PC. PSA failure was associated with an increased ACM risk among men with no or minimal (adjusted hazard ratio, 1.59; 95% CI, 1.03 to 2.46; P = .04), but not moderate or severe comorbidity (adjusted hazard ratio, 1.75; 95% CI, 0.76 to 3.99; P = .19). Conclusion Recommending treatment on the basis of reduced PSA failure observed from early results of RCTs is unlikely to prolong survival in men with moderate-to-severe comorbidity but may prolong survival in men with no or minimal comorbidity, providing evidence to support discussing the early results with these men.

Assessment of M867, a selective caspase-3 inhibitor, in an orthotopic mouse model for non-small cell lung carcinoma.

Radiation-induced lung injury (RILI) is a significant dose limiting complication of thoracic radiation for lung, breast, and esophageal cancer. Strategies for increasing the therapeutic index of radiation involve the use of radiosensitizing agents. We investigated the potential of M867 to sensitize non-small cell lung cancer (NSCLC) to radiation in vivo, while assessing its protective effects in normal lung parenchyma. H460-Luc2 cells were implanted into the mediastinum of athymic nude mice, which were separated into four treatment groups: control, M867, radiation therapy (RT) or combination. H460-Luc2 cell cultures were treated in parallel. Tumor growth was followed using bioluminescence imaging. Immunohistochemistry staining was used to detect phospho-Smad2/3 and cleaved caspase-3 expression. Western blot was done for the detection of cleaved caspase-3 and phospho-Smad2/3. TUNEL assays were used to measure apoptosis. M867+RT group had significantly increased tumor growth inhibition relative to either treatment alone (p=0.02). M867+RT was associated with increased levels of apoptosis (p<0.01), but combination treatment was associated with a decrease in caspase-dependent apoptosis relative to RT alone (p<0.01). We found that this increase in apoptosis in the M867+RT group was due to caspase-independent cell death. Based on early biomarker analyses of phospho-Smad 2/3 and cleaved caspase-3, M867+RT had a radio-protective effect on normal lung parenchyma. M867 may increase the therapeutic ratio of RT by enhancing the radiosensitivity of NSCLC while mitigating RILI. Further research is warranted to examine the late effects of lung injury and to study differences in the mechanism of action of M867 on lung cancer and normal tissue.

ALK inhibitor PF02341066 (crizotinib) increases sensitivity to radiation in non-small cell lung cancer expressing EML4-ALK.

Crizotinib (PF02341066) is a tyrosine kinase inhibitor of anaplastic lymphoma kinase (ALK) that has been shown to selectively inhibit growth of cancer cells that harbor the EML4-ALK fusion found in a subset of patients with non-small cell lung cancer (NSCLC). While in clinical trials, PF02341066 has shown a significant therapeutic benefit as a single agent; the effectiveness of combining it with other therapeutic modalities including ionizing radiation remains unknown. To further elucidate the role of PF02341066 in tumor inhibition, we examined its effects alone and in combination with radiation on downstream signaling, apoptosis, and radiosensitivity in two NSCLC cell lines in vitro: H3122, which harbors the EML4-ALK fusion, and H460, which does not. We also examined the in vivo effects of PF02341066 in H3122 mouse xenografts. In the H3122 cell line, PF02341066 inhibited phosphorylation of ALK and its downstream effectors: AKT, ERK, and STAT3. H3122 cells treated with a combination of PF02341066 and radiation showed an increase in cellular apoptosis and were sensitized to radiation therapy (dose enhancement ratio, 1.43; P < 0.0001). Moreover, in an H3122 xenograft model, the combined treatment resulted in greater tumor growth inhibition than either treatment alone (P < 0.05). None of these effects was observed in the EML4-ALK-negative H460 cells. Our findings indicate that PF02341066 acts as a radiation sensitizer in cells harboring the EML4-ALK fusion, providing a rationale for a clinical trial combining ALK inhibitor with radiation in the NSCLCs expressing ALK.

Role of insulin-like growth factor-1 signaling pathway in cisplatin-resistant lung cancer cells.

PURPOSE: The development of drug-resistant phenotypes has been a major obstacle to cisplatin use in non-small-cell lung cancer. We aimed to identify some of the molecular mechanisms that underlie cisplatin resistance using microarray expression analysis. METHODS AND MATERIALS: H460 cells were treated with cisplatin. The differences between cisplatin-resistant lung cancer cells and parental H460 cells were studied using Western blot, MTS, and clonogenic assays, in vivo tumor implantation, and microarray analysis. The cisplatin-R cells were treated with human recombinant insulin-like growth factor (IGF) binding protein-3 and siRNA targeting IGF-1 receptor. RESULTS: Cisplatin-R cells illustrated greater expression of the markers CD133 and aldehyde dehydrogenase, more rapid in vivo tumor growth, more resistance to cisplatin- and etoposide-induced apoptosis, and greater survival after treatment with cisplatin or radiation than the parental H460 cells. Also, cisplatin-R demonstrated decreased expression of insulin-like growth factor binding protein-3 and increased activation of IGF-1 receptor signaling compared with parental H460 cells in the presence of IGF-1. Human recombinant IGF binding protein-3 reversed cisplatin resistance in cisplatin-R cells and targeting of IGF-1 receptor using siRNA resulted in sensitization of cisplatin-R-cells to cisplatin and radiation. CONCLUSIONS: The IGF-1 signaling pathway contributes to cisplatin-R to cisplatin and radiation. Thus, this pathway represents a potential target for improved lung cancer response to treatment.

Terameprocol (tetra-O-methyl nordihydroguaiaretic acid), an inhibitor of Sp1-mediated survivin transcription, induces radiosensitization in non-small cell lung carcinoma.

INTRODUCTION: Survivin, an inhibitor of apoptosis protein and key regulator of mitosis, is up-regulated in a variety of cancers and is often associated with a worse prognosis. Terameprocol down-regulates the Sp1-mediated transcription of survivin and Cdk1, which is important for cell cycle progression and many other proteins. Survivin inhibition has previously been shown to result in the induction of apoptosis and radiosensitization. METHODS: This study examined the effects of terameprocol administration on survivin transcription and expression in HCC2429 and H460 lung cancer cells. We also examined the combined effects of radiation and terameprocol on apoptosis and radiosensitivity. RESULTS: Using immunoblot analysis and luciferase assays, we confirmed that terameprocol decreases survivin transcription and protein expression. Ultimately, however, decreases in survivin expression failed to correlate with an increase in apoptosis. Nonetheless, clonogenic assay revealed that terameprocol induces increased radiosensitization in HCC2429 (dose enhancement ratio = 1.26, p = 0.019) and H460 (dose enhancement ratio = 1.18, p = 0.001) cells. Additionally, the data show no effect of terameprocol on cell cycle in either HCC2429 or H460 cells. CONCLUSIONS: Terameprocol significantly enhances the sensitivity of non-small cell lung carcinoma cell lines to radiation therapy, although the mechanism of action remains unclear. Further study is warranted to assess the potential of terameprocol as an agent that may enhance the therapeutic ratio of radiotherapy in lung cancer.

MLN8054, a small molecule inhibitor of aurora kinase a, sensitizes androgen-resistant prostate cancer to radiation.

PURPOSE: To determine whether MLN8054, an Aurora kinase A (Aurora-A) inhibitor causes radiosensitization in androgen-insensitive prostate cancer cells in vitro and in vivo. METHODS AND MATERIALS: In vitro studies consisted of culturing PC3 and DU145 prostate cancer cells and then immunoblotting Aurora A and phospho-Aurora A after radiation and/or nocodazole with MLN8054. Phases of the cell cycle were measured with flow cytometry. PC3 and DU145 cell lines were measured for survival after treatment with MLN8054 and radiation. Immunofluorescence measured γ-H2AX in the PC3 and DU145 cells after treatment. In vivo studies looked at growth delay of PC3 tumor cells in athymic nude mice. PC3 cells grew for 6 to 8 days in mice treated with radiation, MLN8054, or combined for 7 more days. Tumors were resected and fixed on paraffin and stained for von Willebrand factor, Ki67, and caspase-3. RESULTS: In vitro inhibition of Aurora-A by MLN8054 sensitized prostate cancer cells, as determined by dose enhancement ratios in clonogenic assays. These effects were associated with sustained DNA double-strand breaks, as evidenced by increased immunofluorescence for γ-H2AX and significant G2/M accumulation and polyploidy. In vivo, the addition of MLN8054 (30 mg/kg/day) to radiation in mouse prostate cancer xenografts (PC3 cells) significantly increased tumor growth delay and apoptosis (caspase-3 staining), with reduction in cell proliferation (Ki67 staining) and vascular density (von Willebrand factor staining). CONCLUSION: MLN8054, a novel small molecule Aurora-A inhibitor showed radiation sensitization in androgen-insensitive prostate cancer in vitro and in vivo. This warrants the clinical development of MLN8054 with radiation for prostate cancer patients.

Inhibition of JAK2 signaling by TG101209 enhances radiotherapy in lung cancer models.

INTRODUCTION: Persistent STAT3 activation contributes to lung carcinogenesis. Survivin, one of STAT3-regulated genes, is antiapoptotic and confers cancer radioresistance. METHODS: We tested whether TG101209, a small-molecule inhibitor of JAK2 (a STAT3-activating tyrosine kinase), affected survivin expression and sensitized lung cancer to radiation. We investigated whether inhibition of JAK2 signaling with TG101209 can be used to reduce survivin expression and enhance radiosensitivity of lung cancer cells in vitro and tumor growth delay in vivo. JAK2 downstream signaling, including PI3-K/Akt and Ras/MAPK/ERK pathways, was also explored. RESULTS: TG101209 inhibited STAT3 activation and survivin expression and sensitized HCC2429 (dose enhancement ratio = 1.34, p = 0.002) and H460 (dose enhancement ratio = 1.09, p = 0.006) cells to radiation in clonogenic assays. Radiation promoted phospho-Akt and phospho-ERK in H460 cells, while their levels were unchanged in HCC2429. After treatment with TG101209, phospho-ERK protein levels were reduced in both HCC2429 and H460 cells. HCC2429 cells transfected with KRAS-12V mutant were more resistant to radiation- and TG101209-induced apoptosis than wild-type control cells. In vivo, addition of TG101209 to radiation in lung xenografts produced a significant tumor growth delay (>10 days) compared with radiation alone and was well tolerated. Immunohistochemistry staining of tumor sections showed that TG101209 increased apoptosis and decreased cell proliferation and vascular density, suggesting that TG101209 also has antiangiogenic effects. CONCLUSIONS: TG101209 enhanced the effects of radiation in lung cancer in vitro and in vivo. This study suggests the potential utility of selecting lung cancer patients according to KRAS mutation status for future clinical trials testing combination of TG101209 and radiotherapy.

BV6, an IAP antagonist, activates apoptosis and enhances radiosensitization of non-small cell lung carcinoma in vitro.

INTRODUCTION: Defects in the apoptosis pathway limit the effectiveness of radiation in non-small cell lung cancer (NSCLC) therapy. BV6 is an antagonist of cIAP1 and XIAP, members of the inhibitors of apoptosis (IAP) family. We investigated the potential of BV6 to sensitize NSCLC cell lines to radiation. METHODS: HCC193 and H460 lung cancer cell lines were treated with BV6 to investigate the effects of drug administration on cell proliferation, apoptosis, inhibition of XIAP and cIAP1, and radiosensitivity. Subsequent immunoblotting and Hoechst staining were used to determine the role of apoptosis in radiosensitization. Finally, the pathway of apoptosis was characterized by Western blot analysis for cleaved caspase-8 and cleaved caspase-9 and enzyme-linked immunosorbent assays for TNF-α. RESULTS: HCC193 was found to be more sensitive than H460 to BV6-induced apoptosis in a concentration-dependent and time-dependent manner. BV6 significantly sensitized both cell lines to radiation (HCC193-DER = 1.38, p < 0.05 at 1 µM BV6; H460-DER = 1.42, p < 0.05 at 5 µM BV6), but a higher concentration of and longer incubation time with BV6 was necessary for H460 cells. The BV6-induced radiosensitization of HCC193 favored the extrinsic pathway of apoptosis, whereas that of H460 favored the intrinsic pathway. CONCLUSIONS: BV6, an IAP antagonist, significantly enhanced the radiosensitization of HCC193 and H460 cells in vitro. More research is warranted to test the mechanism of action of BV6 and to assess its potential in vivo and in the clinical setting.

A novel bioluminescence orthotopic mouse model for advanced lung cancer.

Lung cancer is the leading cause of cancer-related death in the United States despite recent advances in our understanding of this challenging disease. An animal model for high-throughput screening of therapeutic agents for advanced lung cancer could help promote the development of more successful treatment interventions. To develop our orthotopic lung cancer model, luciferase-expressing A549 cancer cells were injected into the mediastinum of athymic nude mice. To determine whether the model would allow easy monitoring of response to therapeutic interventions, tumors were treated with 30 mg/kg Paclitaxel or were irradiated with 5 fractions of 2 Gy, and tumor burden was monitored using bioluminescence imaging. Evidence of radiation-induced lung injury was assessed using immunohistochemical staining for phospho-Smad2/3 and cleaved caspase-3. We found that tumor implantation recapitulated advanced human lung cancer as evidenced by tumor establishment and proliferation within the mediastinum. The tumor responded to Paclitaxel or radiation as shown by decreased tumor bioluminescence and improved overall survival. Immunohistochemistry revealed increased phospho-Smad2/3 and cleaved caspase-3 in irradiated lungs, consistent with radiation-induced lung injury. This orthotopic lung cancer model may help provide a method to assess therapeutic interventions in a preclinical setting that recapitulates locally advanced lung cancer.

Enhanced radiosensitivity of androgen-resistant prostate cancer: AZD1152-mediated Aurora kinase B inhibition.

Aurora kinase B (AURKB) is critical to the process of mitosis, aiding in chromosome condensation by phosphorylating histone H3. We investigated the effects of AZD1152, an AURKB inhibitor, on radiosensitivity of androgen-insensitive prostate cancer cells. The goal of this study was to test whether AZD1152 increases the susceptibility of hormone-refractory prostate cancer cells to radiation-induced DNA damage and to determine the conditions of AZD1152 treatment that maximize radiosensitization. PC3 and DU145 cells were treated with various AZD1152 doses for various durations to elucidate the conditions that yielded maximal increases in G(2)/M-phase and polyploid cells. To assess DNA damage, γ-H2AX phosphorylation was quantified for cells grown under radiosensitizing conditions and subjected to either no radiation or 5 Gy radiation. Radiosensitivity was determined by clonogenic assays. Cell cycle effects in both cell lines were maximized by treatment with 60 nM AZD1152 for 48 h. AZD1152-treated cells exhibited significantly increased DNA damage 30 min postirradiation (PC3: 100% compared to 68%, P  =  0.035; DU145: 100% compared to 69%, P  =  0.034), with additional DNA damage 6 h postirradiation (PC3: 85% compared to 15%, P  =  0.002; DU145: 67% compared to 21%, P  =  0.012). Radiosensitivity was increased in both cell lines, with dose enhancement ratios of 1.53 for PC3 cells (P  =  0.017) and 1.71 for DU145 cells (P  =  0.02). This study identifies the optimal AZD1152 treatment conditions to maximize the radiosensitization of PC3 and DU145 cells. These results suggest a major role for DNA damage and impairment of DNA repair mechanisms in AZD1152-induced radiosensitization of prostate cancer cells.