MiR-34c downregulation leads to SOX4 overexpression and cisplatin resistance in nasopharyngeal carcinoma.

BACKGROUND: A major cause of disease-related death in nasopharyngeal carcinoma (NPC) is the development of distant metastasis (DM) despite combination chemoradiotherapy treatment. We previously identified and validated a four microRNA (miRNA) signature that is prognostic for DM. In this study, characterization of a key component of this signature, miR-34c, revealed its role in chemotherapy resistance. METHODS: Two hundred forty-six NPC patient biopsy samples were subject to comprehensive miRNA profiling and immunohistochemistry (IHC). Two human normal nasopharyngeal cell lines (immortalized; NP69 and NP460), as well as the NPC cell line C666-1, were used for miR-34c gain-of-function and loss-of-function experiments. Signaling pathways were assessed using quantitative real-time PCR (qRT-PCR) and Western blot. Cell viability was measured using the ATPlite assay. RESULTS: MiR-34c was downregulated in NPC patient samples, and confirmed in vitro to directly target SOX4, a master regulator of epithelial-to-mesenchymal transition (EMT). MiR-34c downregulation triggered EMT-representative changes in NP69 and NP460 whereby Snail, ZEB1, CDH2, and SOX2 were upregulated, while Claudin-1 and CDH1 were downregulated. Phenotypically, inhibition of miR-34c led to cisplatin resistance, whereas miR-34c over-expression sensitized NPC cells to cisplatin. TGFß1 decreased miR-34c and increased SOX4 expression in vitro. The TGFß receptor 1 inhibitor SB431542 reduced SOX4 expression and increased cisplatin sensitivity. Finally, IHC revealed that lower SOX4 expression was associated with improved overall survival in chemotherapy-treated NPC patients. CONCLUSION: miR-34c is downregulated in NPC. Repression of miR-34c was shown to increase SOX4 expression, which leads to cisplatin resistance, while TGFß1 was found to repress miR-34c expression. Taken together, our study demonstrates that inhibition of the TGFß1 pathway could be a strategy to restore cisplatin sensitivity in NPC.

ARTS and Siah collaborate in a pathway for XIAP degradation.

ARTS (apoptosis-related protein in the TGF-ß signaling pathway) is a mitochondrial protein that binds XIAP (X-linked inhibitor of apoptosis protein) upon entering the cytosol, thus promoting cell death. Expression of ARTS is lost in some malignancies. Here, we show that ARTS binds to XIAP at BIR1, a domain distinct from the caspase-binding sites. Furthermore, ARTS interacts with the E3 ligase Siah-1 (seven in absentia homolog 1) to induce ubiquitination and degradation of XIAP. Cells lacking either Siah or ARTS contain higher steady-state levels of XIAP. Thus, ARTS serves as an adaptor to bridge Siah-1 to XIAP, targeting it for destruction.

MicroRNAs in extracellular vesicles: potential cancer biomarkers.

Extracellular vesicles (EV) are small membrane-bound structures that are secreted by various cell types, including tumor cells. Recent studies have shown that EVs are important for cell-to-cell communication, locally and distantly; horizontally transferring DNA, mRNA, microRNA (miRNA), proteins and lipids. In the context of cancer biology, tumor-derived EVs are capable of modifying the microenvironment, promoting tumor progression, immune evasion, angiogenesis and metastasis. miRNAs contained within EVs are functionally associated with cancer progression, metastasis and aggressive tumor phenotypes. These factors, along with their stability in bodily fluids, have led to extensive investigations on the potential role of circulating EV-derived miRNAs as tumor biomarkers. In this review, we summarize the current understanding of circulating EV miRNAs in human cancer, and discuss their clinical utility and challenges in functioning as biomarkers.

The clinical manifestations and molecular pathogenesis of radiation fibrosis.

Advances in radiation techniques have enabled the precise delivery of higher doses of radiotherapy to tumours, while sparing surrounding healthy tissues. Consequently, the incidence of radiation toxicities has declined, and will likely continue to improve as radiotherapy further evolves. Nonetheless, ionizing radiation elicits tissue-specific toxicities that gradually develop into radiation-induced fibrosis, a common long-term side-effect of radiotherapy. Radiation fibrosis is characterized by an aberrant wound repair process, which promotes the deposition of extensive scar tissue, clinically manifesting as a loss of elasticity, tissue thickening, and organ-specific functional consequences. In addition to improving the existing technologies and guidelines directing the administration of radiotherapy, understanding the pathogenesis underlying radiation fibrosis is essential for the success of cancer treatments. This review integrates the principles for radiotherapy dosimetry to minimize off-target effects, the tissue-specific clinical manifestations, the key cellular and molecular drivers of radiation fibrosis, and emerging therapeutic opportunities for both prevention and treatment.

CD8+ Tumor-Infiltrating Lymphocyte Abundance Is a Positive Prognostic Indicator in Nasopharyngeal Cancer.

PURPOSE: Tumor-infiltrating lymphocytes (TIL) are immune cell populations found within tumors, critical in the antigen-specific host immune response. In this study, we aimed to elucidate the prognostic significance of CD3+, CD4+, and CD8+ TILs in nasopharyngeal cancer (NPC). EXPERIMENTAL DESIGN: Immune cell infiltration was quantified in NPC samples (n = 50) using RNA-sequencing (RNA-seq) data based on rearranged T-cell receptor (TCR) reads and the Estimation of Stromal and Immune cells in malignant tumors using expression data (ESTIMATE) immune score tool. The differential abundances of TIL subset populations were also characterized through IHC staining of formalin-fixed, paraffin-embedded samples from a training cohort (n = 35), which was a subset of the RNA-seq cohort (n = 50). RESULTS: In the RNA-seq cohort, patients with higher rearranged TCR reads experienced superior 5- and 10-year overall survival (OS; P < 0.001), and disease-free survival (DFS; P < 0.001). Similarly, patients with higher ESTIMATE immune scores experienced superior 5- and 10-year OS (P = 0.024) and DFS (P = 0.007). In the training cohort, high abundances of CD8+ TILs were significantly associated with improved 5- and 10-year OS (P = 0.003) and DFS (P = 0.005). These findings were corroborated in an independent validation cohort (n = 84), and combined analysis of the training and validation cohorts [n = 119 (35+84)], which further demonstrated improved 5- and 10-year survival in terms of locoregional control (P < 0.001) and distant metastasis (P = 0.03). CONCLUSIONS: Taken together, our study highlights the prognostic value of CD8+ TILs in NPC, and the potential of future investigations into cellular-based immunotherapies employing CD8+ lymphocytes.

Development and Validation of a Risk Model for Breast Cancer-Related Lymphedema.

Importance: Approximately 1 in 5 patients with breast cancer who undergo axillary lymph node dissection will develop lymphedema. To appropriately triage and monitor these patients for timely diagnosis and treatment, robust risk models are required. Objective: To evaluate the prognostic value of mammographic breast density in estimating lymphedema severity. Design, Setting, and Participants: This prognostic study collected data from July 16, 2018, to March 3, 2020, from the electronic health records of patients of the Cancer Rehabilitation and Survivorship Program at the Princess Margaret Cancer Centre in Toronto, Ontario, Canada. Participants included women who had completed curative treatment for a first diagnosis of breast cancer and who were referred to the program. Also included were a sample of patients in the general breast oncology population who were receiving follow-up care at the center during the same period but who were not referred to the program. All patients attended follow-up appointments at the Princess Margaret Cancer Centre from January 1, 2016, to May 1, 2018. The cohort was randomly split 2:1 to group patients into a training cohort and a validation cohort. Exposures: Participant demographic and clinical characteristics included age, sex, body mass index (BMI), medical history, cancer characteristics, and cancer treatment. Main Outcomes and Measures: Spearman correlation coefficient between measured and predicted volume of lymphedema was calculated. Area under the curve (AUC) values were generated for predicting the occurrence of at least mild lymphedema (volume, >200 mL) and severe lymphedema (volume, >500 mL) at the time of initial lymphedema diagnosis. Results: A total of 373 female patients (median [interquartile range] age, 52.3 [45.9-60.1] years) were eligible for this analysis. Multivariate linear regression identified 3 patient factors (age, BMI, and mammographic breast density), 1 cancer factor (number of pathological lymph nodes), and 1 treatment factor (axillary lymph node dissection) as independent prognostic variables. In validation testing, Spearman correlation revealed a statistically significant moderate correlation (coefficient, 0.42; 95% CI, 0.26-0.56; P < .001) between measured volume and predicted volume of lymphedema. The AUC values were 0.72 (95% CI, 0.60-0.83) for predicting the occurrence of mild lymphedema and 0.83 (95% CI, 0.74-0.93) for severe lymphedema. Conclusions and Relevance: This prognostic study found that patients with low breast density appeared to be at a higher risk of developing severe lymphedema. The finding suggests that by combining breast density with established risk factors a multivariate linear regression model could be used to predict the development of lymphedema and provide volumetric estimates of lymphedema severity in patients with breast cancer.

Inflammatory Biomarkers, Hematopoietic Stem Cells, and Symptoms in Breast Cancer Patients Undergoing Adjuvant Radiation Therapy.

BACKGROUND: Fatigue and insomnia are common symptoms experienced by breast cancer patients undergoing adjuvant radiation therapy (RT), yet the underlying mechanisms of these symptoms are unclear. In particular, the roles of hematopoietic stem cells (HSCs) and inflammatory cytokines remain to be elucidated. METHODS: Breast cancer patients (n = 147) completed questionnaires to longitudinally assess symptoms before, during, and after adjuvant RT. Phlebotomies were performed prior to RT, at the second and fifth treatment fractions, end of treatment (EOT), and 1 month after completing RT, assessing for CD34+, CD45+, full hematology, and 17 inflammatory cytokines. The associations between symptoms and all biomarkers were evaluated. All statistical tests were 2-sided. RESULTS: General fatigue and insomnia worsened with RT, with peak levels observed at EOT, which remained statistically significant even after controlling for anxiety and depression (P < .05 for all). CD34+, CD45+, white blood cell, and lymphocyte counts decreased, with the lowest levels also observed at EOT (P < .001). Fatigue and insomnia were associated with changes in both interferon γ-induced protein 10 (IP-10) - (P = .03 and P = .01, respectively) and tumor necrosis factor receptor II (TNF-RII) (P = .02 and P = .006, respectively), while mental fatigue was associated with increased matrix metalloproteinases-2 (MMP-2) levels (P = .03). Patients who received prior chemotherapy demonstrated statistically significantly greater severity in all symptoms, with lower baseline HSC levels. CONCLUSIONS: This is the first longitudinal study to examine linkages between symptoms, HSCs, and cytokines, demonstrating that fatigue and insomnia shared associations with increasing serum levels of IP-10 and TNF-RII, and mental fatigue was associated with increasing serum levels of MMP-2. Our findings highlight opportunities for further research into mechanisms and potential interventions for these symptoms.

Potential use of cetrimonium bromide as an apoptosis-promoting anticancer agent for head and neck cancer.

A potential therapeutic agent for human head and neck cancer (HNC), cetrimonium bromide (CTAB), was identified through a cell-based phenotype-driven high-throughput screen (HTS) of 2000 biologically active or clinically used compounds, followed by in vitro and in vivo characterization of its antitumor efficacy. The preliminary and secondary screens were performed on FaDu (hypopharyngeal squamous cancer) and GM05757 (primary normal fibroblasts), respectively. Potential hit compounds were further evaluated for their anticancer specificity and efficacy in combination with standard therapeutics on a panel of normal and cancer cell lines. Mechanism of action, in vivo antitumor efficacy, and potential lead compound optimizations were also investigated. In vitro, CTAB interacted additively with gamma radiation and cisplatin, two standard HNC therapeutic agents. CTAB exhibited anticancer cytotoxicity against several HNC cell lines, with minimal effects on normal fibroblasts; a selectivity that exploits cancer-specific metabolic aberrations. The central mode of cytotoxicity was mitochondria-mediated apoptosis via inhibition of H(+)-ATP synthase activity and mitochondrial membrane potential depolarization, which in turn was associated with reduced intracellular ATP levels, caspase activation, elevated sub-G(1) cell population, and chromatin condensation. In vivo, CTAB ablated tumor-forming capacity of FaDu cells and delayed growth of established tumors. Thus, using an HTS approach, CTAB was identified as a potential apoptogenic quaternary ammonium compound possessing in vitro and in vivo efficacy against HNC models.

A TR3/Nur77 peptide-based high-throughput fluorescence polarization screen for small molecule Bcl-B inhibitors.

Nuclear receptor TR3/Nur77/NR4A1 binds several antiapoptotic Bcl-2-family proteins (Bcl-B, Bcl-2, Bfl-1) in a non-BH3-dependent manner. A 9-amino-acid peptide derived from full-length TR3 with polyarginine tail (TR3-r8) recapitulates TR3's binding specificity, displaying high affinity for Bcl-B. TR3-r8 peptide was used to screen for small molecule Bcl-B inhibitors. A fluorescence polarization assay (FPA) employing fluorescein isothiocyanate (FITC)-labeled TR3-r8 peptide (FITC-TR3-r8) and Bcl-B protein was optimized, with nonfluorescent TR3-r8 serving to demonstrate reversible, competitive binding. Approximately 50,000 compounds were screened at 3.75 mg/L, yielding 145 reproducible hits with > or =50% FITC-TR3-r8 displacement (a confirmed hit rate of 0.29%). After dose-response analyses and counterscreening with an unrelated FITC-based FPA, 6 candidate compounds remained. Nuclear magnetic resonance (NMR) showed that 2 of these compounds bound Bcl-B, but not glutathione S-transferase (GST) control protein. One Bcl-B-binding compound was unable to displace FITClabeled BH3 peptides from Bcl-B, confirming a unique binding mechanism compared with traditional antagonists of antiapoptotic Bcl-2-family proteins. This compound bound Bcl-B with Kd 1.94 +/- 0.38 microM, as determined by isothermal titration calorimetry. Experiments using Bcl-B overexpressing HeLa cells demonstrated that this compound induced Bcl-B-dependent cell death. The current FPA represents a screen that can identify noncanonical inhibitors of Bcl-2-family proteins.

Imaging and modulating antisense microdistribution in solid human xenograft tumor models.

PURPOSE: The tumor microenvironment is complex and heterogeneous, populated by tortuous irregular vasculature, hypoxic cells, and necrotic regions. These factors can all contribute to the biodistribution difficulties encountered by most cancer therapeutic agents. Antisense oligodeoxynucleotides (ASO) are a class of therapeutics where limited information is available about their distribution within a solid tumor environment. EXPERIMENTAL DESIGN: To assess ASO distribution, a fluorescein-labeled phosphorothionated ASO based on the G3139 mismatch control was injected systemically (i.v.) into tumor-bearing severe combined immunodeficient mice. Hoechst 33342 was injected i.v. to visualize active vasculature. Unstained sections were imaged through tiled fluorescence stereomicroscopy and then quantitated using novel algorithms. Tumor sections from four human tumor models were examined (CaSki, DU-145, C666-1, and C15) for hypoxia, apoptosis/necrosis, and morphology. RESULTS: For all four tumors, ASO accumulated within regions of hypoxia, necrosis, and apoptosis. Scatter plots of ASO versus active vasculature generated for each individual tumor revealed a consistent pattern of distribution of the ASO within each model. In C666-1 xenografts, the slopes of these scatter plots were significantly reduced from 0.41 to 0.16 when pretreated with the antivascular agent ZD6126 48 h before ASO injection. This was accompanied by the formation of large disseminated necrotic regions in the tumor, along with a 13.1 mmHg reduction in interstitial fluid pressure. CONCLUSIONS: These data suggest the possibility that these algorithms might offer a generalizable and objective methodology to describe the distribution of molecular therapeutic agents within a tumor microenvironment and to quantitatively assess distribution changes in response to combination therapies.

Imaging the Modulation of Adenoviral Kinetics and Biodistribution for Cancer Gene Therapy.

See page 841 To explore systemic utilization of Epstein-Barr virus (EBV)-specific transcriptionally targeted adenoviruses, three vectors were constructed to examine kinetics, specificity, and biodistribution: adv.oriP.luc, expressing luciferase under EBV-specific control; adv.SV40luc, expressing luciferase constitutively; and adv.oriP.E1A.oriP.luc, a conditionally replicating adenovirus, expressing both luciferase and E1A. Bioluminescence imaging (BLI) was conducted on tumor-bearing severe combined immunodeficient (SCID) mice (C666-1, EBV-positive human nasopharyngeal cancer) treated intravenously (i.v.) with 3 × 108 infectious units (ifu) of the adenoviral vectors. At 72 hours, adv.oriPluc demonstrated an 8.4-fold higher tumor signal than adv.SV40luc; adv.oriP.E1A.oriP.luc was 26.7-fold higher; however, a significant liver signal was also observed, necessitating further action to improve biodistribution. Several compounds were examined to this end, including norepinephrine, serotonin, clodronate liposomes, and STI571, to determine whether any of these measures could improve adenoviral biodistribution. Each of these interventions was assessed using BLI in mice i.v. injected with adv.oriP.luc. STI571 achieved the highest increase in tumor-to-liver ratio (TLR; 6.6-fold), which was associated with a 59% reduction in tumor interstitial fluid pressure (IFP) along with a decrease in platelet-derived growth factor-ß receptor (PDGFßR) activation. This study reports the favorable modulation by STI571 of the biodistribution of adenoviral vectors, providing a potential approach to improving therapeutic outcome.

hsa­miR­24 suppresses metastasis in nasopharyngeal carcinoma by regulating the c­Myc/epithelial­mesenchymal transition axis.

Distant metastasis is the major contributor to treatment failure and mortality in patients with nasopharyngeal carcinoma (NPC). The lack of effective treatment strategies for metastatic NPC is the major cause for the low survival rate. Therefore, it is crucial to understand the molecular mechanisms underlying NPC metastasis and to identify potential biomarkers for targeted therapy. MicroRNA (miRNAs or miRs) have been shown to play an important role in tumorigenesis and metastasis. In the present study, we aimed to evaluate the significance of hsa­miR­24 in NPC metastasis. Significantly lower hsa­miR­24 levels were observed in NPC metastatic tumors and higher hsa­miR­24 levels were associated with longer progression­free and metastasis­free survival durations. hsa­miR­24 overexpression inhibited cell proliferation, invasion and migration. Using bioinformatics approaches together with functional luciferase reporter assays, we demonstrated that the c­Myc 3'­UTR was a direct target of hsa­miR­24 in regulating NPC metastasis. Protein profiling analysis revealed that a high c­Myc expression was inversely associated with metastasis­free overall survival and with epithelial­mesenchymal transition (EMT). Furthermore, the overexpression of hsa­miR­24 decreased NPC cell invasive ability induced by the overexpression of c­Myc, associated with EMT epithelial marker (E­cadherin) restoration. Thus, on the whole, the findings of this study demonstrate that hsa­miR­24 suppresses metastasis in NPC by regulating the c­Myc/EMT axis, suggesting that hsa­miR­24 may be used as a prognostic factor and as a novel target for the prevention of NPC metastasis.

Dysregulation of the MiR-449b target TGFBI alters the TGFß pathway to induce cisplatin resistance in nasopharyngeal carcinoma.

Despite the improvement in locoregional control of nasopharyngeal carcinoma (NPC), distant metastasis (DM), and chemoresistance persist as major causes of mortality. This study identified a novel role for miR-449b, an overexpressed gene in a validated four-miRNA signature for NPC DM, leading to chemoresistance via the direct targeting of transforming growth factor beta-induced (TGFBI). In vitro shRNA-mediated downregulation of TGFBI induced phosphorylation of PTEN and AKT, increasing cisplatin resistance. Conversely, the overexpression of TGFBI sensitized the NPC cells to cisplatin. In NPC patients treated with concurrent chemoradiotherapy (CRT), the overall survival (OS) was significantly inversely correlated with miR-449b, and directly correlated with both TGFBI mRNA and protein expression, as assessed by RNA sequencing and immunohistochemistry (IHC). Mechanistically, co-immunoprecipitation demonstrated that TGFBI competes with pro-TGFß1 for integrin receptor binding. Decreased TGFBI led to increased pro-TGFß1 activation and TGFß1 canonical/noncanonical pathway-induced cisplatin resistance. Thus, overexpression of miR-449b decreases TGFBI, thereby altering the balance between TGFBI and pro-TGFß1, revealing a novel mechanism of chemoresistance in NPC.

Radiomic Biomarkers to Refine Risk Models for Distant Metastasis in HPV-related Oropharyngeal Carcinoma.

PURPOSE: Distant metastasis (DM) is the main cause of death for patients with human papillomavirus (HPV)-related oropharyngeal cancers (OPCs); yet, there are few reliable predictors of DM in this disease. The role of quantitative imaging (ie, radiomic) analysis was examined to determine whether there are primary tumor features discernible on imaging studies that are associated with a higher risk of DM developing. METHODS AND MATERIALS: Radiation therapy planning computed tomography scans were retrieved for all nonmetastatic p16-positive OPC patients treated with radiation therapy or chemoradiation therapy at a single institution between 2005 and 2010. Radiomic biomarkers were derived from each gross tumor volume. The biomarkers included 4 representative radiomic features from tumor first-order statistics, shape, texture, and wavelet groups, as well as a combined 4-feature signature. Univariable Cox proportional hazards models for DM risk were identified. The discriminative performance of prognostic univariable and multivariable models was compared using the concordance index (C-index). Subgroup analyses were performed. RESULTS: There were 300 HPV-related OPC patients who were eligible for the analysis. A total of 36 DM events occurred within a median follow-up period of 5 years. On univariable analysis, top results included the 4 representative radiomic features (C-index, 0.670-0.686; P < .001), the radiomic signature (C-index, 0.670; P < .001), tumor stage (C-index, 0.633; P < .001), tumor diameter (C-index, 0.653; P < .001), and tumor volume (C-index, 0.674; P < .001), which demonstrated moderate discrimination of DM risk. Combined clinical-radiomic models yielded significantly improved performance (C-index, 0.701-0.714; P < .05). In subgroup analyses, the radiomic biomarkers consistently stratified patients for DM risk, particularly for those cohorts with greater risks (C-index, 0.663-0.796), such as patients with stage III disease. CONCLUSIONS: Radiomic biomarkers appear to classify DM risk for patients with nonmetastatic HPV-related OPC. Radiomic biomarkers could be used either alone or with other clinical characteristics in the assignment of DM risk in future HPV-related OPC clinical trials.

Prognostic significance of the Epstein-Barr virus, p53, Bcl-2, and survivin in nasopharyngeal cancer.

PURPOSE: Nasopharyngeal cancer (NPC) is a malignant epithelial carcinoma which is intimately associated with EBV. The latent presence of EBV affects the function of p53, Bcl-2, and survivin. We thus investigated the relationship between EBV status, p53, Bcl-2, and survivin in biopsy specimens from patients with primary NPC. EXPERIMENTAL DESIGN: Archival formalin-fixed, paraffin-embedded NPC biopsies were evaluated in 80 patients treated with curative radiation from a single institution. The presence of EBV was determined using EBER in situ hybridization, whereas p53, Bcl-2, and survivin were assessed using immunohistochemistry. RESULTS: The majority of NPC specimens in this patient cohort were EBER-positive (64 of 78, or 82%), which in turn, was significantly associated with ethnicity (P = 0.0007), and WHO subtype 2A/2B (P = 0.04). EBER-positive tumors were also associated with p53 (P = 0.002), Bcl-2 (P = 0.04), and nuclear survivin (P = 0.03) expression. Patients with EBER-positive NPC fared better, with a 10-year overall survival of 68% versus 48% for EBER-negative patients (P = 0.03). For nuclear survivin, patients with either low or high nuclear survivin fared worse than patients with intermediate survivin expression (P = 0.05), suggesting that there is an optimal proportion of survivin-expressing cells for best function and clinical outcome. CONCLUSIONS: With an extended median follow-up time of 11.4 years, EBV status remains a strong predictor for overall survival in NPC. EBV-positive NPC has strong molecular associations with p53, Bcl-2, and survivin expression. Furthermore, we provide clinical data revealing the potentially dual nature of survivin in predicting clinical outcome.

Benzethonium chloride: a novel anticancer agent identified by using a cell-based small-molecule screen.

PURPOSE: This study aims to identify a novel therapeutic agent for head and neck cancer and to evaluate its antitumor efficacy. EXPERIMENTAL DESIGN: A cell-based and phenotype-driven high-throughput screening of approximately 2,400 biologically active or clinically used compounds was done using a tetrazolium-based assay on FaDu (hypopharyngeal squamous cancer) and NIH 3T3 (untransformed mouse embryonic fibroblast) cells, with secondary screening done on C666-1 (nasopharyngeal cancer) and GM05757 (primary normal human fibroblast) lines. The "hit" compound was assayed for efficacy in combination with standard therapeutics on a panel of human cancer cell lines. Furthermore, its mode of action (using transmission electron microscopy and flow cytometry) and its in vivo efficacy (using xenograft models) were evaluated. RESULTS: Benzethonium chloride was identified as a novel cancer-specific compound. For benzethonium (48-hour incubation), the dose required to reduce cell viability by 50% was 3.8 micromol/L in FaDu, 42.2 micromol/L in NIH 3T3, 5.3 micromol/L in C666-1, and 17.0 micromol/L in GM05757. In vitro, this compound did not interfere with the effects of cisplatin, 5-fluorouracil, or gamma-irradiation. Benzethonium chloride induced apoptosis and activated caspases after 12 hours. Loss of mitochondrial membrane potential (DeltaPsiM) preceded cytosolic Ca2+ increase and cell death. In vivo, benzethonium chloride ablated the tumor-forming ability of FaDu cells, delayed the growth of xenograft tumors, and combined additively with local tumor radiation therapy. Evaluation of benzethonium chloride on the National Cancer Institute/NIH Developmental Therapeutics Program 60 human cancer cell lines revealed broad-range antitumor activity. CONCLUSIONS: This high-throughput screening identified a novel antimicrobial compound with significant broad-spectrum anticancer activity.

Potential use of alexidine dihydrochloride as an apoptosis-promoting anticancer agent.

Despite advances in surgery, radiation, and chemotherapy, novel therapeutics are needed for head and neck cancer treatment. The objective of this current study was to evaluate alexidine dihydrochloride as a novel compound lead for head and neck cancers. Using a tetrazolium-based assay, the dose required to reduce cell viability by 50% (ED50) was found to be approximately 1.8 micromol/L in FaDu (human hypopharyngeal squamous cancer) and approximately 2.6 micromol/L in C666-1 (human undifferentiated nasopharyngeal cancer) cells. In contrast, the ED50 values were much higher in untransformed cells, specifically at approximately 8.8 micromol/L in GM05757 (primary normal human fibroblast), approximately 8.9 micromol/L in HNEpC (primary normal human nasal epithelial), and approximately 19.6 micromol/L in NIH/3T3 (mouse embryonic fibroblast) cells. Alexidine dihydrochloride did not interfere with the activities of cisplatin, 5-fluorouracil, or radiation, and interacted in a less-than-additive manner. DNA content analyses and Hoechst 33342 staining revealed that this compound induced apoptosis. Alexidine dihydrochloride-induced mitochondrial damage was visualized using transmission electron microscopy. Mitochondrial membrane potential (DeltaPsiM) depolarization was detectable after only 3 hours of treatment, and was followed by cytosolic Ca2+ increase along with loss of membrane integrity/cell death. Caspase-2 and caspase-9 activities were detectable at 12 hours, caspase-8 at 24 hours, and caspase-3 at 48 hours. FaDu cell clonogenic survival was reduced to < 5% with 1 micromol/L alexidine dihydrochloride, and, correspondingly, this compound decreased the in vivo tumor-forming potential of FaDu cells. Thus, we have identified alexidine dihydrochloride as the first bisbiguanide compound with anticancer specificity.

Combination bcl-2 antisense and radiation therapy for nasopharyngeal cancer.

PURPOSE: A wide variety of tumors depend on the dysregulation of Bcl-2 family proteins for survival. The resulting apoptotic block can often provide a mechanism for resistance to anticancer treatments, such as chemotherapy and radiation. This current study evaluates the efficacy of combining systemically delivered Bcl-2 phosphorothioate antisense (Bcl-2 ASO) and radiation for nasopharyngeal cancer therapy. RESULTS: Antisense uptake was unaffected by 0, 3, or 6 Gy radiation. Radiation decreased the fraction of viable C666-1 cells to 60%, with a further decrease to 40% in combination with Bcl-2 ASO. Despite a modest in vitro effect, Bcl-2 ASO alone caused the regression of established xenograft tumors in mice, extending survival by 15 days in a C666-1 and by 6 days in a C15 model. The survival times for mice treated with both Bcl-2 ASO and radiation increased by 52 days in C666-1 and by 20 days in C15 tumors. This combination resulted in a more-than-additive effect in C666-1 tumors. Less impressive gains observed in C15 tumors might be attributable to higher expression of antiapoptotic Bcl-2 family proteins and limited drug distribution in the tumor. Retreatment of C666-1 tumors with the Bcl-2 ASO-radiation combination, however, was effective, resulting in mice surviving for >80 days relative to untreated controls. CONCLUSIONS: Our results show that the Bcl-2 ASO and radiation combination is a highly potent therapy for nasopharyngeal cancer. Further examination of combination therapy with radiation and other Bcl-2 family-targeted anticancer agents in both preclinical and clinical settings is definitely warranted.