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(1) Destabilization of microtubule dynamics is a primary strategy to inhibit fast growing tumor cells. The low cytotoxic derivative of microtubule inhibitor D-24851, named BPR0C261 exhibits antitumor activity via oral administration. In this study, we investigated if BPR0C261 could modulate the radiation response of human non-small cell lung cancer (NSCLC) cells with or without p53 expression. (2) Different doses of BPR0C261 was used to treat human NSCLC A549 (p53+/+) cells and H1299 (p53−/−) cells. The cytotoxicity, radiosensitivity, cell cycle distribution, DNA damage, and protein expression were evaluated using an MTT assay, a colony formation assay, flow cytometry, a comet assay, and an immunoblotting analysis, respectively. (3) BPR0C261 showed a dose-dependent cytotoxicity on A549 cells and H1299 cells with IC50 at 0.38 μM and 0.86 μM, respectively. BPR0C261 also induced maximum G2/M phase arrest and apoptosis in both cell lines after 24 h of treatment with a dose-dependent manner. The colony formation analysis demonstrated that a combination of low concentration of BPR0C261 and X-rays caused a synergistic radiosensitizing effect on NSCLC cells. Additionally, we found that a low concentration of BPR0C261 was sufficient to induce DNA damage in these cells, and it increased the level of DNA damage induced by a fractionation radiation dose (2 Gy) of conventional radiotherapy. Furthermore, the p53 protein level of A549 cell line was upregulated by BPR0C261. On the other hand, the expression of PTEN tumor suppressor was found to be upregulated in H1299 cells but not in A549 cells under the same treatment. Although radiation could not induce PTEN in H1299 cells, a combination of low concentration of BPR0C261 and radiation could reverse this situation. (4) BPR0C261 exhibits specific anticancer effects on NSCLC cells by the enhancement of DNA damage and radiosensitivity with p53-dependent and p53-independent/PTEN-dependent manners. The combination of radiation and BPR0C261 may provide an important strategy for the improvement of radiotherapeutic treatment.

Hypopharyngeal cancer (HPC) accounts for the lowest survival rate among all types of head and neck cancers (HNSCC). However, the therapeutic approach for HPC still needs to be investigated. In this study, a theranostic 188Re-liposome was prepared to treat orthotopic HPC tumors and analyze the deregulated microRNA expressive profiles. The therapeutic efficacy of 188Re-liposome on HPC tumors was evaluated using bioluminescent imaging followed by next generation sequencing (NGS) analysis, in order to address the deregulated microRNAs and associated signaling pathways. The differentially expressed microRNAs were also confirmed using clinical HNSCC samples and clinical information from The Cancer Genome Atlas (TCGA) database. Repeated doses of 188Re-liposome were administrated to tumor-bearing mice, and the tumor growth was apparently suppressed after treatment. For NGS analysis, 13 and 9 microRNAs were respectively up-regulated and down-regulated when the cutoffs of fold change were set to 5. Additionally, miR-206-3p and miR-142-5p represented the highest fold of up-regulation and down-regulation by 188Re-liposome, respectively. According to Differentially Expressed MiRNAs in human Cancers (dbDEMC) analysis, most of 188Re-liposome up-regulated microRNAs were categorized as tumor suppressors, while down-regulated microRNAs were oncogenic. The KEGG pathway analysis showed that cancer-related pathways and olfactory and taste transduction accounted for the top pathways affected by 188Re-liposome. 188Re-liposome down-regulated microRNAs, including miR-143, miR-6723, miR-944, and miR-136 were associated with lower survival rates at a high expressive level. 188Re-liposome could suppress the HPC tumors in vivo, and the therapeutic efficacy was associated with the deregulation of microRNAs that could be considered as a prognostic factor.

Non–small cell lung cancer (NSCLC) is a highly morbid and mortal cancer type that is difficult to eradicate using conventional chemotherapy and radiotherapy. Little is known about whether radionuclide-based pharmaceuticals can be used for treating NSCLC. Here we embedded the therapeutic radionuclide 188Re in PEGylated (PEG is polyethylene glycol) liposomes and investigated the biodistribution, pharmacokinetics, and therapeutic efficacy of this nanoradiopharmaceutical on NSCLC using a xenograft lung tumor model and the reporter gene imaging techniques. Methods: Human NSCLC NCI-H292 cells expressing multiple reporter genes were used in this study. 188Re was conjugated to N,N-bis(2-mercaptoethyl)-N′,N′-diethylethylenediamine (BMEDA) and loaded into the PEGylated liposome to form a 188Re-liposome. The tumor growth rates and localizations were confirmed using bioluminescent imaging and SPECT/CT after the 188Re-BMEDA or 188Re-liposome was intravenously injected. The accumulation of the nanodrug in various organs was determined by the biodistribution analysis and the nano-SPECT/CT system. The pharmacokinetic and dosimetric analyses were further determined using WinNonlin and OLINDA/EXM, respectively. Results: The biodistribution and nano-SPECT/CT imaging showed that PEGylated 188Re-liposome could efficiently accumulate in xenograft tumors formed by NCI-H292 cells that were subcutaneously implanted in nude mice. Pharmacokinetic analysis also showed that the retention of 188Re-liposome was longer than that of 188Re-BMEDA. In an orthotopic tumor model, ex vivo γ counting revealed that the uptake of 188Re-liposome was detected in tumor lesions but not in surrounding normal lung tissues. Moreover, we evaluated the therapeutic efficacy using bioluminescent imaging and showed that the lung tumor growth was suppressed but not eradicated by 188Re-liposome. The life span of 188Re-liposome–treated mice was 2-fold longer than that of untreated control mice. Conclusion: The results of biodistribution, pharmacokinetics, estimated dosimetry, nano-SPECT/CT, and bioluminescent imaging suggest that the PEGylated liposome–embedded 188Re could be used for the treatment of human lung cancers.

Ionizing radiation induces cellular senescence to suppress cancer cell proliferation. However, it also induces deleterious bystander effects in the unirradiated neighboring cells through the release of senescence-associated secretory phenotypes (SASPs) that promote tumor progression. Although autophagy has been reported to promote senescence, its role is still unclear. We previously showed that radiation induces senescence in PTTG1-depleted cancer cells. In this study, we found that autophagy was required for the radiation-induced senescence in PTTG1-depleted breast cancer cells. Inhibition of autophagy caused the cells to switch from radiation-induced senescence to apoptosis. Senescent cancer cells exerted bystander effects by promoting the invasion and migration of unirradiated cells through the release of CSF2 and the subsequently activation of the JAK2-STAT3 and AKT pathways. However, the radiation-induced bystander effects were correlated with the inhibition of endogenous autophagy in bystander cells, which also resulted from the activation of the CSF2-JAK2 pathway. The induction of autophagy by rapamycin reduced the radiation-induced bystander effects. This study reveals, for the first time, the dual role of autophagy in radiation-induced senescence and bystander effects.

Aim Effects of radiofrequency ablation (RFA) combining immunoadjuvant glycated chitosan (GC) on tumor control and potent cytokine responses were investigated in a syngeneic breast tumor model. Materials and methods Murine 4T1 breast carcinoma cells harboring the luciferase reporter gene were used to evaluate the tumor growth rate and metastasis in vivo using bioluminescent imaging. Plasma of RFA/GC-treated tumor-bearing mice was collected for ex vivo cytotoxicity analysis and mouse chemokine array assays. Results Tumor growth and systemic metastasis were suppressed by combined RFA and GC when tumor size reached 300 mm3, not detected, however, when tumor size reached 800 mm3 The survival rate of mice bearing small tumors was also higher than that of large ones after RFA-GC treatment. Plasma extracted from RFA-GC-treated small tumor-bearing mice exhibited cytotoxicity on cultured 4T1 cells. Moreover, reduced tumor growth-related cytokines and increased antitumor-related cytokines were detected in the plasma collected. Conclusion RFA combining GC could control tumor progression with induced potent antitumor cytokine responses.

Purpose Radiotherapy is one of the best choices for cancer treatment. However, various tumor cells exhibit resistance to irradiation-induced apoptosis. The development of new strategies to trigger cancer cell death besides apoptosis is necessary. This study investigated the role of securin in radiation-induced apoptosis and senescence in human cancer cells. Methods and Materials Cell survival was determined using clonogenic assays. Western blot analysis was used to analyze levels of securin, caspase-3, PARP, p53, p21, Rb, γ-H2AX, and phospho-Chk2. Senescent cells were analyzed using a β-galactosidase staining assay. A securin-expressed vector (pcDNA-securin) was stably transfected into securin-null HCT116 cells. Securin gene knockdown was performed by s mall interfering RNA and small hairpin RNA in HCT116 and MDA-MB-231 cells, respectively. Results Radiation was found to induce apoptosis in securin wild type HCT116 cells but induced senescence in securin-null cells. Restoration of securin reduced senescence and increased cell survival in securin-null HCT116 cells after irradiation. Radiation-induced γ-H2AX and Chk2 phosphorylation were induced transiently in securin-wild-type cells but exhibited sustained activation in securin-null cells. Securin gene knockdown switches irradiation-induced apoptosis to senescence in both HCT116 p53-null and MDA-MB-231 cells. Conclusions Our results demonstrated that the level of securin expression plays a determining role in the radiosensitivity and fate of cells. Depletion of securin impairs DNA repair after irradiation, increasing DNA damage and promoting senescence in the residual surviving cells regardless of functional p53 expression. The knockdown of securin may contribute to a novel radiotherapy protocol for the treatment of human cancer cells that are resistant to irradiation.

Cofilin, a ubiquitously expressed actin binding protein, is responsible for the formation of the actin cytoskeleton and is indispensable for cell cycle control. However, the association between cofilin expression and the cell cycle remains to be elucidated. In this study, we found that the expression level of cofilin upregulated in G(1) phase-arrested confluent cells, while knockdown of cofilin expression by small interference RNA (siRNA) in these cells led to a reduction in the population of G(1) cells. To investigate the role of cofilin in the control of G(1) phase progression, a tet-on gene expression system was introduced to overexpress different concentrations of cofilin in cells. The results showed that G(1) phase progression was blocked following induction of exogenous cofilin. A survey of the cell cycle proteins controlling the G(1) phase progression revealed that the cyclin-dependent kinase inhibitor (CKI) p27(kip1) was the primary molecule induced by overexpressed cofilin in a time and dose dependent manner. Upregulated p27(kip1) repressed phosphorylation of the retinoblastoma protein (Rb) mediated by cyclin D1/CDK4 activity. Conversely, siRNA against p27(kip1) expression in the cofilin overexpressing cells released the G(1) phase arrest. Furthermore, we found that overexpression of cofilin led to induction of p27(kip1) gene promoter transactivation using luciferase reporter gene assay. This effect was associated with increase of p27(kip1) mRNA transiently. In addition, inhibition of threonine-187 phosphorylation of p27(kip1) protein for ubiquitinyl-proteasomal mediated degradation was also involved in upregulation of p27(kip1). These data suggest that cofilin expression and its regulation of p27(kip1) expression is important for the control of G(1) phase progression.

The Rho–LIM-kinase (LIMK) signaling pathway, believed to be involved in the regulation of tumor invasion, specifically regulates the activity of cofilin. However, it is unclear whether cofilin plays a pivotal role in tumor invasiveness. In this paper we show using a tet-on gene expression system that over-expression of cofilin inhibits the invasiveness of human lung cancer H1299 cells. Over-expressed cofilin disrupts the actin cytoskeleton at the leading edge of the cell and up-regulates p27kip1, which is known to be involved in regulating cell motility. Removal of cofilin over-expression normalizes the p27kip1 level and concomitantly restores the invasiveness of the cultured cells. These findings suggest that excessive cofilin production might prevent cancer cell invasion.

Cofilin is an actin-associated protein that belongs to the actin depolymerization factor/cofilin family and is important for regulation of actin dynamics. Cofilin can import actin monomers into the nucleus under certain stress conditions, however the biological effects of nuclear transport are unclear. In this study, we found that over-expression of cofilin led to increased radiation sensitivity in human non-small lung cancer H1299 cells. Cell survival as determined by colony forming assay showed that cells over-expressing cofilin were more sensitive to ionizing radiation (IR) than normal cells. To determine whether the DNA repair capacity was altered in cofilin over-expressing cells, comet assays were performed on irradiated cells. Repair of DNA damage caused by ionizing radiation was detected in cofilin over-expressing cells after 24 h of recovery. Consistent with this observation, the key components for repair of DNA double-strand breaks, including Rad51, Rad52, and Ku70/Ku80, were down-regulated in cofilin over-expressing cells after IR exposure. These findings suggest that cofilin can influence radiosensitivity by altering DNA repair capacity.

This study investigates molecular mechanisms underlying cell cycle arrest when cells are exposed to high levels of oxygen (hyperoxia). Hyperoxia has previously been shown to increase expression of the cell cycle regulators p53 and p21. In the current study, we found that p53-deficient human lung adenocarcinoma H1299 cells failed to induce p21 or growth arrest in G1when exposed to 95% oxygen. Instead, cells arrested in S and G2. Stable expression of p53 restored induction of p21 and G1arrest without affecting mRNA expression of the other Cip or INK4 G1kinase inhibitors. To confirm the role of p21 in G1arrest, we created H1299 cells with tetracycline-inducible expression of enhanced green fluorescent protein (EGFP), EGFP fused to p21 (EGFp21), or EGFP fused to p27 (EGFp27), a related cell cycle inhibitor. The amino terminus of p21 and p27 bind cyclin-dependent kinases (Cdk), whereas the carboxy terminus of p21 binds the sliding clamp proliferating cell nuclear antigen (PCNA). EGFp21 or EGFp27, but not EGFP by itself, restored G1arrest during hyperoxia. When separately overexpressed, the amino-terminal Cdk and carboxy-terminal PCNA binding domains of p21 each prevented cells from exiting G1during exposure. These findings demonstrate that exposure in vitro to hyperoxia exerts G1arrest through p53-dependent induction of p21 that suppresses Cdk and PCNA activity. Because PCNA also participates in DNA repair, these results raise the possibility that p21 also affects repair of oxidized DNA.

Background and purpose Cancer stem cells exhibit distinctive cellular metabolism compared with the more differentiated counterparts or normal cells. We aimed to investigate the impact of a novel radionuclide anti-cancer agent 188 Re-Liposome on stemness markers' expression and cellular metabolism in an ovarian cancer model. Material and methods A 2×2 factorial experiment was designed in which factor 1 represented the drug treatment comparing 188 Re-BMEDA, a free form of 188 Re, with 188 Re-Liposome, a nanoparticle-encapsulated form of 188 Re. Factor 2 represented the delivery route, comparing intravenous with intraperitoneal delivery. Results Intraperitoneal delivery of 188 Re-Liposome predominantly killed the CSCs-like cells in tumours and switched metabolism from glycolysis to oxidative phosphorylation. Further, intraperitoneal delivery of 188 Re-Liposome treatment was able to block epithelial-to-mesenchymal transition (EMT) and reactivate p53 function. Collectively, these molecular changes led to a striking tumour-killing effect. Conclusions Radionuclides encapsulated in liposomes may represent a novel treatment for ovarian cancer when delivered intraperitoneally (a type of loco-regional delivery). In the future, this concept may be further extended for the treatment of several relevant cancers that have been proved to be suitable for loco-regional delivery of therapeutic agents, such as colon cancer, gastric cancer, and pancreatic cancer.

Securin overexpression correlates with poor prognosis in various tumours. We have previously shown that securin depletion promotes radiation-induced senescence and enhances radiosensitivity in human cancer cells. However, the underlying molecular mechanisms and the paracrine effects remain unknown. In this study, we showed that radiation induced senescence in securin-deficient human breast cancer cells involving the ATM/Chk2 and p38 pathways. Conditioned medium (CM) from senescent cells promoted the invasion and migration of non-irradiated cancer and endothelial cells. Cytokine assay analysis showed the up-regulation of various senescence-associated secretory phenotypes (SASPs). The IL-6/STAT3 signalling loop and platelet-derived growth factor-BB (PDGF-BB)/PDGF receptor (PDGFR) pathway were important for CM-induced cell migration and invasion. Furthermore, CM promoted angiogenesis in the chicken chorioallantoic membrane though the induction of IL-6/STAT3- and PDGF-BB/PDGFR-dependent endothelial cell invasion. Taken together, our results provide the molecular mechanisms for radiation-induced senescence in securin-deficient human breast cancer cells and for the SASP responses.

A previous report has indicated that over-expression of cofilin-1 (CFL-1), a member of the actin depolymerizing factor (ADF)/cofilin protein family, enhances cellular radiosensitivity. This study explores the involvement of various DNA damage responses and repair systems in the enhanced cellular radiosensitivity as well as assessing the role of CFL-1 phosphorylation in radiosensitivity.Human non-small lung cancer H1299 cells harboring a tet-on gene expression system were used to induce exogenous expression of wild-type CFL-1. Colony formation assays were used to determine cell survival after γ-ray exposure. DNA damage levels were determined by Comet assay. DNA repair capacity was assessed by fluorescence-based DNA repair analysis and antibody detection of various repair proteins. The effects of CFL-1 phosphorylation on radiation responses were explored using two mutant CFL-1 proteins, S3D and S3A. Finally, endogenous CFL-1 phosphorylation levels were investigated using latrunculin A (LA), cytochalasin B (CB) and Y27632.When phosphorylatable CFL-1 was expressed, radiosensitivity was enhanced after exposure to γ-rays and this was accompanied by DNA damage. Phosphorylated histone H2AX (γ-H2AX) and p53-binding protein-1 (53BP1) foci, as well as Chk1/2 phosphorylation, were apparently suppressed, although ataxia telangiectasia mutated (ATM) kinase activation was apparently unaffected. In addition, two radiation-induced double-strand break (DSB) repair systems, namely homologous recombination repair (HRR) and non-homologous end joining (NHEJ), were suppressed. Moreover, over-expression of CFL-1 S3D and CFL-1 S3A both enhanced radiosensitivity. However, enhanced radiosensitivity and reduced γ-H2AX expression were only detected in cells treated with LA which increased endogenous phospho-CFL-1, and not in cells treated with Y27632, which dephosphorylates CFL-1.CFL-1 over-expression enhances radiosensitivity and this is associated with reduced DNA repair capacity. Although phosphorylated CFL-1 seems to be involved in radiosensitivity, further studies are required to address the importance of CFL-1 activity to the regulation of radiosensitivity.

Tumor growth is dependent on a kinetic model that is based on the progression of cell proliferation and cell loss. The parameters for cell proliferation during tumor progression include the cell-cycle time (Tc), growth fraction (GF), and potential tumor-doubling time (Tpot). In contrast, the cell-loss factor is determined by Tpot and the actual time for doubling of the tumor volume (Td).1 The causes of cell loss include malnutrition and lack of oxygen caused by rapid proliferation, necrosis and apoptosis, immunological attack, escape from the primary site, and exfoliation.2 These conditions can be regarded as stresses for cells residing in a rapidly growing tumor. Whether cells escaping from these stresses inherit or obtain resistance abilities is unknown. The tracking and characterization of living cells in a tumor are important for cancer treatment. Reporter-gene imaging is an indirect approach to labeling cells for image-based in vivo tracking and targeting by different modalities.3 This method is especially important for tracking cell viability in vivo because gene transcription and translation occur only in living cells.4 In addition, the transmission of genes to progeny is in principle not diminished or diluted if the reporter genes can replicate within the genomes of host cells.5 Firefly luciferase and fluorescent proteins are canonical reporter genes used for bioluminescent imaging and optical imaging, respectively. For radionuclide-based reporter-gene imaging, herpes simplex virus type-1 thymidine kinase (HSV1-tk) is commonly used because it can uptake a broad range of radiolabeled nucleoside analogues by substrate phosphorylation for imaging the target cells in vivo.6 Expression of the HSV1-tk reporter gene can be used for living cell tracking by positron emission tomography (PET) or single-photon emission computed tomography (SPECT), depending on the types of radionuclide-labeled substrates. For instance, iodine-123-labeled 5-iodo-2′-fluoro-1-beta-𝒟-arabinofuranosyluracil (123I-FIAU) is the most reliable radiolabeled nucleoside analogues for SPECT imaging of HSV1-tk gene expression because it exhibits high tumor/background ratio in vivo.7, 8 As described above, the sensitivity and specificity of 123I-FIAU on cancer detection is based on the expression of HSV1-tk reporter gene in the transduced cancer cells. These cancer cells can be distinguished from the non-cancer cells without HSV1-tk genes using the radionuclide imaging modality. Technically, cultured cancer cells are stably transduced with HSV1-tk genes and implanted into animals for tumor formation. Using SPECT imaging, this cancer population can be distinguished from non-cancer portion in vivo by injecting 123I-FIAU as a radiotracer that are only accumulated in HSV1-tk gene expressing cancer cells.7 Multimodality reporter-gene imaging using coexpressed luciferase/fluorescent proteins and HSV1-tk has been reported to be a powerful tool for basic biological and preclinical research.9, 10 In addition, PET and SPECT can be merged with computed tomography (CT) to obtain functional/anatomic imaging with high sensitivity and spatial resolution. Although reporter-gene imaging is widely used for functional studies in vivo, concerns regarding the safety and transduction pathways of exogenous genes hamper the clinical application of this approach. Viral-mediated methods are commonly used for the transduction of reporter genes, but the uncontrolled infection and random genomic integration of genes of interest currently limit the clinical application of these methods.11 In contrast, nonviral gene delivery is more acceptable in the clinic because biocompatible materials can be used, and the safety of these approaches is relatively easily assessed by pharmacokinetic and pharmacodynamic studies.12 The piggyBac transposon system has recently attracted a great deal of attention because the system is a nonviral gene-delivery approach that uses DNA-transposition ability for the stable expression of exogenous genes via a ‘cut-and-paste' mechanism.13 The beauty of this system includes its known integration sites at ‘TTAA' sequences and intron-preferred positions, mammalian compatibility, large cargo capacity, and its ability to be removed from the integration site without changing the DNA sequence.14 In practice, this system requires a helper plasmid that encodes the piggyBac transposase gene to facilitate the transposition of exogenous gene.15 The piggyBac transposon system has been applied in induced pluripotent stem cells, cancer research, and immunotherapy.16, 17 However, the use of this system has been less frequently reported in multimodality reporter-gene imaging of tumor progression. Cancer stem cells (CSCs, or tumor-initiating cells) belong to the hierarchy model that a subset of rare cell population inherits stem cell-like characteristics, including self-renewal and generation of non-tumorigenic progeny.18 This theory has intrigued many researchers in recent years because CSCs are resistant to chemoradiotherapy and are likely to be the cause of tumor recurrence and metastasis.19 However, the identification of CSCs in vivo remains a challenge because of the lack of suitable markers for this purpose. If CSCs naturally resist environmental stresses, it would be speculated that this population may also escape from cell loss during tumor progression. More evidence is required to support this hypothesis. The percentage of cell loss during tumor progression is approximately 40–90%, depending on the cancer type.1 The remnant viable cells may be important for promoting tumor growth and metastasis. Reporter-gene imaging should be ideal to track these living cells for further investigation of their characteristics. In this study, we established a syngeneic tumor model derived from 4T1 murine breast carcinomas transduced with monomeric red fluorescent protein (mRFP)/HSV1-tk dual reporter genes using the piggyBac transposon system. A combination of optical imaging and SPECT/CT fusion imaging using 123I-FIAU as a probe was exploited to track the remnant living cells in late-stage primary tumors. Furthermore, ex vivo studies showed that the surviving cells exhibited CSC-like characteristics. These findings may contribute to therapeutic designs for cancer treatment.

Glioblastoma multiforme (GBM) is the most malignant brain tumor with the characteristics of highly infiltrative growth and recurrent rate. In this study, we used animal imaging and molecular expressive profiles to investigate the characteristics of the primary tumor (GBM-3) cells and recurrent tumor (S1R1) cells from different GBM patients.Bioluminescent imaging and 3T magnetic resonance imaging (MRI) were used for assessing the orthotopical tumor development of GBM cells harboring a polycistronic reporter gene system. Western blot analysis and quantitative polymerase chain reaction were used to compare the molecular expressive profiles of two types of GBM cells.S1R1 cells exhibited apparent invasive ability compared to GBM-3 cells using in vitro invasion assay. In vivo bioluminescent imaging showed that intracranial tumors are formed by both types of GBM cells, but the bioluminescent signal was also detected in the lumbar region at late-stage tumor formed by S1R1 cells. The MRI showed that intracranial tumors formed by S1R1 cells were highly infiltrative compared to that formed by GBM-3 cells. Additionally, these two GBM types expressed different patterns of molecules associated with tumor development. Moreover, the suppressive effects of interleukine-23 (IL-23) on xenograft tumors formed by both GBM types were detected using bioluminescent imaging.The current data suggest that the in vivo growth behaviors and therapeutic responses of the primary and recurrent human GBMs were comparable using the reporter gene imaging, and different molecular expressive profiles exist between these two GBM types.

N-Heterocyclic indolyl glyoxylamide compounds are derived from the antimicrotubule agent D-24851, which exhibits anticancer activity after oral administration. The actions of these compounds on lung cancer cells are still unknown. Here, we investigated the effects of two N-heterocyclic indolyl glyoxylamides, BPR0C259 and BPR0C123, on non-small human lung cancer cells.3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the half maximal inhibitory concentration (IC(50)), cell viability and radiation response of A549 cells and H1299 cells. Apoptosis was determined by sub-G(1) ratio, colony formation assay and caspase-3 activation. Cell cycle distribution was detected using flow cytometry.Both compounds were able to inhibit the viability of human lung cancer cells, although the IC(50) of BPR0C123 was lower than that of BPR0C259. Both compounds induced significant sub-G1 and caspase-3 activation as low as 0.1 μM in both cell lines. These effects were independent of p53 activation because the level of serine-15 phosphorylated p53 was not affected after drug treatment. Furthermore, both compounds induced similar levels of G(2)/M phase arrest and radiosensitivity in these lung cancer cells.Current data suggest that N-heterocyclic indolyl glyoxylamides can suppress the proliferation of and potentially increase radiosensitivity of human lung cancer cells.

Arsenic exerts its cytotoxicity via the generation of reactive oxygen species and inhibition of DNA repair. How arsenic disturbs oxidative DNA damage repair is, however, unclear. We found that arsenic trioxide (ATO), like ultraviolet (UV) irradiation, induced the expression of xeroderma pigmentosum group C (XPC) but not of xeroderma pigmentosum A in a human glioma cell line, U87. To explore the role of XPC in the toxic effects of ATO, small interfering RNA was used to silence XPC (siXPC) in U87 cells. siXPC cells were more susceptible to UV irradiation and ATO-induced cell death than control cells. Increased siXPC cell death induced by ATO was accompanied by increased senescence and autophagy. Because increased DNA strand breaks in siXPC cells were observed only when cells were concomitantly treated with ATO and DNA repair inhibitors, XPC silencing apparently did not interfere with repair of ATO-induced DNA damage. Although intracellular ROS levels were not significantly enhanced in siXPC cells, ATO treatment did result in increased 8-hydroxy-2'-deoxyguanosine and hyperoxidized peroxiredoxin. Enhanced superoxide production and autophagy by ATO in siXPC cells were suppressed by co-incubation with N-acetylcysteine (NAC). Furthermore, XPC silencing caused decreased glutathione levels and increased catalase and Mn-superoxide dismutase activities. Increased catalase activity in siXPC cells was suppressed by ATO treatment. XPC silencing also enhanced reporter activity of activator protein-1, whereas enhanced activity was suppressed by NAC. Taken together, our results indicate that XPC silencing causes increased ATO susceptibility by disturbing redox homeostasis rather than reducing DNA repair.

The herpes simplex virus type 1 thymidine kinase (HSV1-tk)/green fluorescent protein (TKGFP) dual-reporter gene and a multimodality imaging approach play a critical role in monitoring therapeutic gene expression, immune cell trafficking, and protein–protein interactions in translational molecular–genetic imaging. However, the cytotoxicity and low temporal resolution of TKGFP limits its application in studies that require a rapid turnover of the reporter. The purpose of this study was to construct a novel mutant TKGFP fusion reporter gene with low cytotoxicity and high temporal resolution for use in the real-time monitoring of temporal dynamics and spatial heterogeneity of hypoxia-inducible factor 1 (HIF-1) signal transduction activity mediated by hypoxia and reoxygenation in vitro and in vivo. Methods: Destabilized TKGFP was produced by inserting the nuclear export signal (NES) sequence at the N terminus and fusing the degradation domain of mouse ornithine decarboxylase (dMODC) at the C terminus. The stability of TKGFP in living NG4TL4 cells was determined by Western blot analysis, HSV1-tk enzyme activity assay, and flow cytometric analysis. The suitability of NESTKGFP:dMODC as a transcription reporter was investigated by linking it to a promoter consisting of 8 copies of hypoxia-responsive elements, whose activities depend on HIF-1. The dynamic transcriptional events mediated by hypoxia and reoxygenation were monitored by NESTKGFP:dMODC or TKGFP and determined by optical imaging and PET. Results: Unlike TKGFP, NESTKGFP:dMODC was unstable in the presence of cycloheximide and showed a short half-life of protein and enzyme activity. Rapid turnover of NESTKGFP:dMODC occurred in a 26S proteasome–dependent manner. Furthermore, NESTKGFP:dMODC showed an upregulated expression and low cytotoxicity in living cells. Studies of hypoxia-responsive TKGFP and NESTKGFP:dMODC expression showed that NESTKGFP:dMODC as a reporter gene had better temporal resolution than did TKGFP for monitoring the dynamic transcriptional events mediated by hypoxia and reoxygenation; the TKGFP expression level was not optimal for the purpose of monitoring. Conclusion: In translational molecular–genetic imaging, NESTKGFP:dMODC as a reporter gene, together with optical imaging and PET, allows the direct monitoring of transcription induction and easy determination of its association with other biochemical changes.

Oxaliplatin, a chemotherapeutic drug, induces DNA double-strand breaks (DSBs) and apoptosis in colorectal cancer cells. It has been shown that gamma-H2AX acts as a marker of DSBs. However, the molecular events associated with oxaliplatin-mediated cell cycle arrest and cell death remain unclear. In this study, we investigated the roles of p53 and gamma-H2AX following oxaliplatin treatment, as they are important effector proteins for apoptosis and DSB repair, respectively. Both phosphorylated-p53 (Ser-15) and gamma-H2AX were up-regulated and accumulated in the nuclei of p53-wild type human colorectal cancer HCT116 cells after exposure to oxaliplatin. Concomitantly, oxaliplatin-induced G2/M arrest was associated with a reduction in both cyclin B1 expression and phosphorylated-CDC2 (Thr-161). Release of G2/M arrest by caffeine was accompanied by a decrease in the levels of p53/p21; however, gamma-H2AX levels were unchanged. Furthermore, inhibition of p53 phosphorylation by pifithrin-alpha was sufficient to reduce the oxaliplatin-induced up-regulation of gamma-H2AX and apoptosis. Oxaliplatin-induced gamma-H2AX via a p53-independent pathway but did not cause caspase-3 activation in p53-null HCT116 cells. Interestingly, no changes were observed in the H2AX gene knockdown with regards to oxaliplatin-induced G2/M arrest in p53-wild type and S phase arrest in p53-null HCT116 cells. Taken together, these data indicate that a molecular pathway involving p53, gamma-H2AX and cell cycle arrest plays a pivotal role in the cellular response to oxaliplatin.

The tumor suppressor p21WAF/CIP1 mediates the proliferation arrest via p53-dependent or -independent gene transactivation following distinct environmental stresses. In this study, we show that direct destabilization of the actin cytoskeleton by actin-targeting reagents leads to a p53-independent up-regulation of p21WAF/CIP1. The actin-targeting agent cytochalasin B (10 microM) quickly disrupted the actin cytoskeleton of p53 wild-type and p53-null cells accompanied by up-regulation of p21WAF/CIP1. Nevertheless, both total p53 and ser-15 phosphorylated p53 were not accumulated concomitantly, compared to the effect caused by ionizing irradiation. P53-independent up-regulation of p21WAF/CIP1 was also observed by two other actin-targeting agents cytochalasin D and latrunculin B, but not by the microtubule inhibitor colcemid. Furthermore, we showed that p21WAF/CIP1 mRNA level was not increased, whereas the protein degradation was delayed. A reduction of ubiquitination for p21WAF/CIP1 protein was detected using immunoprecipitation/immunoblot analysis. Up-regulation of p21WAF/CIP1 was not associated with cytotoxicity induced by cytochalasin B that influenced DNA integrity and plating efficiency only after 24 h of treatment. In addition, up-regulated p21WAF/CIP1 was accompanied by reduction of phosphorylation on retinoblastoma (Rb) protein in p53-null cells, implying that p21WAF/CIP1 might in part account for the molecular regulation of cytochalasin B induced G1 phase arrest. Together, current results suggest that p21WAF/CIP1 level can be mediated by actin organization in the absence of p53 via a post-transcriptional machinery, and it may contribute to the growth ablation by agents targeting the actin cytoskeleton.

The significance of actin cytoskeleton on cell growth was historically studied using toxic drugs, such as cytochalasin. However, it is possible that unpredictable effects of these agents may have influenced the reported observations. In our study, we have established a drug-free system using cofilin overexpression to investigate the relationship between actin filaments and cell cycle progression. Cofilin is a member of the actin depolymerization factor (ADF)/cofilin family, cofilin cDNA was cloned to a tetracycline-inducible gene expression vector and stably transfected to human lung cancer H1299 epithelial cells. Destabilization of actin filaments and morphological change was detected in cofilin overexpressing cells by actin analysis and microscopy, respectively. Measurements of growth rates showed that cell proliferation was retarded in cells with overexpressed cofilin. Also, cell cycle analysis showed that approx 90% of cofilin overexpressing cells were arrested in G1 phase, which is consistent with previous reports that drug-mediated disruption of actin filaments can cause G1 phase arrest. Taken together, cofilin overexpression cell model provides evidence that the effects of actin cytoskeletal destabilization on cell cycle progression can be studied using molecular approach instead of drug.

Cellular sensitivity to ionizing radiation (IR) treatment is a complex biologic phenomenon that is affected by several processes, namely the ability of the cell to detect and repair DNA damage, regulate cell cycle division, and execute apoptosis. Because the p53 tumor suppressor protein is implicated in the regulation of each of these processes, radiation sensitivity of H1299 p53-null human lung carcinoma cells was evaluated after restoration of wild-type p53. Expression of wild-type p53 in radiation-resistant H1299 cells reinstated a radiation-sensitive phenotype that was not fully explained by cell death resulting from p53-mediated apoptosis. In addition, we show that p53 alters radiation sensitivity only in the G1 phase of the cell cycle, whereas S- and G2/M-phase cells were unaffected by p53 status. To determine the mechanism of p53-induced G1-phase radiation sensitivity, we investigated the G1/S checkpoint response to IR in H1299/p53 cells. We show that H1299/p53 cells arrest in the G1 phase in a p53-dependent manner as a result of transcriptional activation of p21WAF1/Cip1. To determine if p53-induced radiation sensitivity was the result of a reproductive death from accumulated p21 protein expression, p21 was independently induced in H1299 parental cells. However, induction of p21 was not sufficient to account for the enhanced radiation sensitivity in H1299/p53 cells. Together, these data indicate that p53 modulates radiation sensitivity in the G1 phase of the cell cycle through mechanisms independent of p53-mediated transcriptional activation of p21 and cell cycle arrest.

Cellular senescence is a state of irreversible growth arrest; however, the metabolic processes of senescent cells remain active. Our previous studies have shown that radiation induces senescence of human breast cancer cells that display low expression of securin, a protein involved in control of the metaphase–anaphase transition and anaphase onset. In this study, the protein expression profile of senescent cells was resolved by two-dimensional gel electrophoresis to investigate associated metabolic alterations. We found that radiation induced the expression and activation of glyceraldehyde-3-phosphate dehydrogenase that has an important role in glycolysis. The activity of lactate dehydrogenase A, which is involved in the conversion of pyruvate to lactate, the release of lactate and the acidification of the extracellular environment, was also induced. Inhibition of glycolysis by dichloroacetate attenuated radiation-induced senescence. In addition, radiation also induced activation of the 5′-adenosine monophosphate-activated protein kinase (AMPK) and nuclear factor kappa B (NF-κB) pathways to promote senescence. We also found that radiation increased the expression of monocarboxylate transporter 1 (MCT1) that facilitates the export of lactate into the extracellular environment. Inhibition of glycolysis or the AMPK/NF-κB signalling pathways reduced MCT1 expression and rescued the acidification of the extracellular environment. Interestingly, these metabolic-altering signalling pathways were also involved in radiation-induced invasion of the surrounding, non-irradiated breast cancer and normal endothelial cells. Taken together, radiation can induce the senescence of human breast cancer cells through metabolic alterations.

Stimulation of the host immune system is crucial in cancer treatment. In particular, nonspecific immunotherapies, when combined with other traditional therapies such as radiation and chemotherapy, may induce immunity against primary and metastatic tumors. In this study, we demonstrate that a novel, non-toxic immunoadjuvant, glycated chitosan (GC), decreases the motility and invasion of mammalian breast cancer cells in vitro and in vivo. Lung metastatic ratios were reduced in 4T1 tumor-bearing mice when intratumoral GC injection was combined with local high-intensity focused ultrasound (HIFU) treatment. We postulate that this treatment modality stimulates the host immune system to combat cancer cells, as macrophage accumulation in tumor lesions was detected after GC-HIFU treatment. In addition, plasma collected from GC-HIFU-treated tumor-bearing mice exhibited tumor-specific cytotoxicity. We also investigated the effect of GC on epithelial-mesenchymal transition-related markers. Our results showed that GC decreased the expression of Twist-1 and Slug, proto-oncogenes commonly implicated in metastasis. Epithelial-cadherin, which is regulated by these genes, was also upregulated. Taken together, our current data suggest that GC alone can reduce cancer cell motility and invasion, whereas GC-HIFU treatment can induce immune responses to suppress tumor metastasis in vivo.

Cofilin-1, a non-muscle isoform of actin regulatory protein that belongs to the actin-depolymerizing factor (ADF)/cofilin family is known to affect cancer development. Previously, we found that over-expression of cofilin-1 suppressed the growth and invasion of human non-small cell lung cancer (NSCLC) cells in vitro. In this study, we further investigated whether over-expression of cofilin-1 can suppress tumor growth in vivo, and performed a microRNA array analysis to better understand whether specific microRNA would be involved in this event. The results showed that over-expression of cofilin-1 suppressed NSCLC tumor growth using the xenograft tumor model with the non-invasive reporter gene imaging modalities. Additionally, cell motility and invasion were significantly suppressed by over-expressed cofilin-1, and down-regulation of matrix metalloproteinase (MMPs) -1 and -3 was concomitantly detected. According to the microRNA array analysis, the let-7 family, particularly let-7b and let-7e, were apparently up-regulated among 248 microRNAs that were affected after over-expression of cofilin-1 up to 7days. Knockdown of let-7b or let-7e using chemical locked nucleic acid (LNA) could recover the growth rate and the invasion of cofilin-1 over-expressing cells. Next, the expression of c-myc, LIN28 and Twist-1 proteins known to regulate let-7 were analyzed in cofilin-1 over-expressing cells, and Twist-1 was significantly suppressed under this condition. Up-regulation of let-7 microRNA by over-expressed cofilin-1 could be eliminated by co-transfected Twist-1 cDNA. Taken together, current data suggest that let-7 microRNA would be involved in over-expression of cofilin-1 mediated tumor suppression in vitro and in vivo.

Sestrin 2 (SESN2) is a stress-inducible protein required for maintaining redox homeostasis. However, its mode of action remains to be clarified. In this study, we found that SESN2 is induced in human glioblastoma U87 cells following ionizing radiation (IR). SESN2 silencing not only results in increased oxidative stress but also sensitizes U87 cells to IR. Intriguingly, we found SESN2 silencing significantly increases the expression of platelet-derived growth factor receptor β (PDGFRβ). Using a double knockdown technique, we showed that inhibition of PDGFRβ accumulation in SESN2-silencing cells protects the cells from the deleterious effects induced by SESN2 silencing. Taken together, we revealed that PDGFRβ accumulation is associated with increased oxidative stress and cellular damage in SESN2 silenced human glioblastoma U87 cells.

Background 1-{4-[Bis(2-chloroethyl)amino]phenyl}-3-[2-methyl-5-(4-methylacridin-9-ylamino)phenyl]urea (BO-1051) is an N-mustard DNA alkylating agent reported to exhibit antitumor activity. Here we further investigate the effects of this compound on radiation responses of human gliomas, which are notorious for the high resistance to radiotherapy. Methods The clonogenic assay was used to determine the IC50 and radiosensitivity of human glioma cell lines (U87MG, U251MG and GBM-3) following BO-1051. DNA histogram and propidium iodide-Annexin V staining were used to determine the cell cycle distribution and the apoptosis, respectively. DNA damage and repair state were determined by γ-H2AX foci, and mitotic catastrophe was measure using nuclear fragmentation. Xenograft tumors were measured with a caliper, and the survival rate was determined using Kaplan-Meier method. Results BO-1051 inhibited growth of human gliomas in a dose- and time-dependent manner. Using the dosage at IC50, BO-1051 significantly enhanced radiosensitivity to different extents [The sensitizer enhancement ratio was between 1.24 and 1.50 at 10% of survival fraction]. The radiosensitive G2/M population was raised by BO-1051, whereas apoptosis and mitotic catastrophe were not affected. γ-H2AX foci was greatly increased and sustained by combined BO-1051 and γ-rays, suggested that DNA damage or repair capacity was impaired during treatment. In vivo studies further demonstrated that BO-1051 enhanced the radiotherapeutic effects on GBM-3-beared xenograft tumors, by which the sensitizer enhancement ratio was 1.97. The survival rate of treated mice was also increased accordingly. Conclusions These results indicate that BO-1051 can effectively enhance glioma cell radiosensitivity in vitro and in vivo. It suggests that BO-1051 is a potent radiosensitizer for treating human glioma cells.