Galactosylated poly(ethylene glycol)-chitosan-graft-polyethylenimine as a gene carrier for hepatocyte-targeting

Chitosan and chitosan derivatives have been proposed as alternative and biocompatible cationic polymers for non-viral gene delivery. However, the low transfection efficiency and low specificity of chitosan is an aspect of this approach that must be addressed prior to any clinical applications. In the present study a chitosan derivative, galactosylated poly(ethylene glycol)-chitosan-graft-polyethylenimine (Gal-PEG-CHI-g-PEI), was investigated as a potential hepatocyte-targeting gene carrier. The composition of Gal-PEG-CHI-g-PEI was characterized using (1)H nuclear magnetic resonance ((1)H NMR), and the particle size and zeta potential of Gal-PEG-CHI-g-PEI/DNA complexes were measured using dynamic light scattering (DLS). The Gal-PEG-CHI-g-PEI exhibited lower cytotoxicity compared to PEI 25K as a control. Likewise, Gal-PEG-CHI-g-PEI/DNA complexes showed good hepatocyte specificity. Furthermore, Gal-PEG-CHI-g-PEI/DNA complexes transfected liver cells more effectively than PEI 25K in vivo after intravenous (i.v.) administration. Together, these results suggest that Gal-PEG-CHI-g-PEI, which has improved transfection efficiency and hepatocyte specificity both in vitro and in vivo, may be useful for gene therapy.

High dietary inorganic phosphate increases lung tumorigenesis and alters Akt signaling

RATIONALE

Phosphate (Pi) is an essential nutrient to living organisms. Recent surveys indicate that the intake of Pi has increased steadily. Our previous studies have indicated that elevated Pi activates the Akt signaling pathway. An increased knowledge of the response of lung cancer tissue to high dietary Pi may provide an important link between diet and lung tumorigenesis.

OBJECTIVES

The current study was performed to elucidate the potential effects of high dietary Pi on lung cancer development.

METHODS

Experiments were performed on 5-week-old male K-ras(LA1) lung cancer model mice and 6-week-old male urethane-induced lung cancer model mice. Mice were fed a diet containing 0.5% Pi (normal Pi) and 1.0% Pi (high Pi) for 4 weeks. At the end of the experiment, all mice were killed. Lung cancer development was evaluated by diverse methods.

MEASUREMENT AND MAIN RESULTS

A diet high in Pi increased lung tumor progression and growth compared with normal diet. High dietary Pi increased the sodium-dependent inorganic phosphate transporter-2b protein levels in the lungs. High dietary consumption of Pi stimulated pulmonary Akt activity while suppressing the protein levels of tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 as well as Akt binding partner carboxyl-terminal modulator protein, resulting in facilitated cap-dependent protein translation. In addition, high dietary Pi significantly stimulated cell proliferation in the lungs of K-ras(LA1) mice.

CONCLUSIONS

Our results showed that high dietary Pi promoted tumorigenesis and altered Akt signaling, thus suggesting that careful regulation of dietary Pi may be critical for lung cancer prevention as well as treatment.

MicroRNA miR-214 regulates ovarian cancer cell stemness by targeting p53/Nanog

Previous studies have shown aberrant expression of miR-214 in human malignancy. Elevated miR-214 is associated with chemoresistance and metastasis. In this study, we identified miR-214 regulation of ovarian cancer stem cell (OCSC) properties by targeting p53/Nanog axis. Enforcing expression of miR-214 increases, whereas knockdown of miR-214 decreases, OCSC population and self-renewal as well as the Nanog level preferentially in wild-type p53 cell lines. Furthermore, we found that p53 is directly repressed by miR-214 and that miR-214 regulates Nanog through p53. Expression of p53 abrogated miR-214-induced OCSC properties. These data suggest the critical role of miR-214 in OCSC via regulation of the p53-Nanog axis and miR-214 as a therapeutic target for ovarian cancer.

Poly(ester amine)-mediated, aerosol-delivered Akt1 small interfering RNA suppresses lung tumorigenesis

RATIONALE

The low efficiency of conventional therapies in achieving long-term survival of patients with lung cancer calls for the development of novel therapeutic options. Recent advances in aerosol-mediated gene delivery have provided the possibility of an alternative for the safe and effective treatment of lung cancer.

OBJECTIVES

To demonstrate the feasibility and emphasize the importance of noninvasive aerosol delivery of Akt1 small interfering RNA (siRNA) as an effective and selective option for lung cancer treatment.

METHODS

Nanosized poly(ester amine) polymer was synthesized and used as a gene carrier. An aerosol of poly(ester amine)/Akt1 siRNA complex was delivered into K-ras(LA1) and urethane-induced lung cancer models through a nose-only inhalation system. The effects of Akt1 siRNA on lung cancer progression and Akt-related signals were evaluated.

MEASUREMENTS AND MAIN RESULTS

The aerosol-delivered Akt1 siRNA suppressed lung tumor progression significantly through inhibiting Akt-related signals and cell cycle.

CONCLUSIONS

The use of poly(ester amine) serves as an effective carrier, and aerosol delivery of Akt1 siRNA may be a promising approach for lung cancer treatment and prevention.

miR-491 Inhibits Osteosarcoma Lung Metastasis and Chemoresistance by Targeting αB-crystallin

Dysregulated microRNAs (miRNAs) play an important role in osteosarcoma (OS) progression. In the present study, we investigate the clinical significance of serum miR-491 level and the potential role of miR-491 in OS lung metastasis and chemoresistance. Clinical data show that the level of miR-491 was decreased in serum from OS patients compared with healthy control subjects, and that a decreased serum miR-491 level is correlated with increased metastasis, poor chemoresponse, and lower survival rate in OS patients. In vitro and in vivo experiments show that overexpression of miR-491 suppresses OS cell lung metastasis, whereas it enhances cisplatin (CDDP)-induced tumor growth inhibition and apoptosis. In contrast, inhibition of miR-491 stimulates OS cell lung metastasis and suppresses CDDP-induced tumor growth inhibition and apoptosis. Furthermore, we demonstrate that miR-491 exerts its role by directly targeting αB-crystallin (CRYAB) in OS. Our findings suggest that serum level of miR-491 has potential as a biomarker for predicting OS progression and prognosis of OS patients. Additionally, restoration of miR-491 may be a novel strategy for inhibiting OS lung metastasis and overcoming OS cell resistance to chemotherapy.

Poly(beta-amino ester) as a carrier for si/shRNA delivery in lung cancer cells

Efficient delivery of small interfering RNA (siRNA) or small hairpin RNA (shRNA) is a critical concern in RNA interference (RNAi) studies. In the present study, we evaluated biodegradable poly(beta-amino ester) (PAE) carrier composed of low molecular weight polyethylenimine and poly(ethylene glycol) for si/shRNA delivery in lung cancer cells. PAE carrier successfully delivered EGFP (enhanced green fluorescence protein) siRNA (siGFP) and silenced EGFP expression. The silencing achieved with PAE carrier was found to be nearly 1.5 times superior and safer than standard PEI25K. Also, our PAE carrier exhibited superior Akt1 shRNA delivery (shAkt) and thereby silenced oncoprotein Akt1 efficiently. PAE-shAkt mediated Akt1 knock-down hindered cancer cell growth in Akt1 specific manner. Superior shAkt delivery and low cytotoxicity of PAE carrier promoted Akt1 knock-down specific apoptosis, while low delivery efficiency and high cytotoxicity of PEI25K carrier mainly exhibited undesirable necrosis. Moreover, basic cancer properties like cell proliferation, malignancy and metastasis were reduced more efficiently using PAE-shAkt system. These findings demonstrated the potential of PAE as an alternative to PEI25K in si/shRNA-based RNAi studies.

miR-382 inhibits tumor growth and enhance chemosensitivity in osteosarcoma

Dysregulation of miRNAs is involved in osteosarcoma (OS). Here, we demonstrate that miR-382 is decreased in specimens of OS patients with a poor chemoresponse compared to those with a good chemoresponse. In addition, our clinical data show that decreased miR-382 was associated with poor survival in OS patients. Overexpression of miR-382 inhibited cell growth and chemoresistance by targeting KLF12 and HIPK3, respectively. In contrast, inhibition of miR-382 or overexpression of target genes stimulated OS cell growth and chemoresistance both in vitro and in vivo. Taken together, these findings suggest that miR-382 is a tumor suppressor miRNA and induction of miR-382 is a potential strategy to inhibit OS progression.

The combination of RAD001 and NVP-BEZ235 exerts synergistic anticancer activity against non-small cell lung cancer in vitro and in vivo

The phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) signaling axis has emerged as a novel target for cancer therapy. Agents that inhibit PI3K, mTOR or both are currently under development. The mTOR allosteric inhibitor, RAD001, and the PI3K/mTOR dual kinase inhibitor, BEZ235, are examples of these agents. We were interested in developing strategies to enhance mTOR-targeted caner therapy. In this study, we found that BEZ235 alone effectively inhibited the growth of rapamycin-resistant cancer cells. Interestingly, the combination of sub-optimal concentrations of RAD001 and BEZ235 exerted synergistic inhibition of the growth of human lung cancer cells along with induction of apoptosis and G1 arrest. Furthermore, the combination was also more effective than either agent alone in inhibiting the growth of lung cancer xenografts in mice. The combination showed enhanced effects on inhibiting mTOR signaling and reducing the expression of c-Myc and cyclin D1. Taken together, our results suggest that the combination of RAD001 and BEZ235 is a novel strategy for cancer therapy.

Nestin expression in different tumours and its relevance to malignant grade

BACKGROUND

Nestin, an intermediate filament (IF) protein, is expressed in proliferating progenitor cells of developmental and regenerating tissues, and is identified as a neuroepithelial precursor cell marker. Recently, nestin was detected in some neoplasms such as glioma, ependymoma, melanoma, rhabdomyosarcoma, gastrointestinal stromal tumour (GIST), and testicular stromal tumour. Moreover, the expression intensity of nestin exhibited significant correlation with the malignant grade of glioma.

AIMS

To detect the expression of nestin in different tumours and to analyse the relationship between the expression of nestin and the malignant grade of the tumours.

METHODS

Formalin-fixed and paraffin-embedded surgical samples of neoplastic tissues were obtained from the Department of Pathology of Sun Yat-sen University. Histological analysis and immunohistochemical staining for nestin were performed. Histoscores were analysed by semi-quantitative evaluation.

RESULTS

Nestin was expressed predominantly in the cytoplasm of angiosarcoma, pancreatic adenocarcinoma and GIST samples, and some tumour cells expressed in the nucleus. There was a statistically significant difference between the histoscore of nestin in high malignant GIST (2.2366 (0.6920)) and that in low malignant GIST (1.3783 (0.4268)) (p = 0.003); and also between that in high malignant angiosarcoma (1.9188 (0.2069)) and that in low malignant angiosarcoma (0.6474 (0.3273)) (p = 0.000). Cavernous angioma did not express nestin. The histoscore of nestin in high malignant pancreatic adenocarcinoma (7/14) was 1.1767 (0.4676), and that in low malignant pancreatic adenocarcinoma (3/8) was 0.6577 (0.0056) (no significant difference, p = 0.112).

CONCLUSIONS

Results suggest that the expression of nestin may play an important role in the development of some neoplasms such as GIST and angiosarcoma.

Augmentation of NVP-BEZ235's anticancer activity against human lung cancer cells by blockage of autophagy

Autophagy is a cellular lysosomal degradation pathway essential for regulation of cell survival and death to maintain homeostasis. This process is negatively regulated by mammalian target of rapamycin (mTOR) signaling and often counteracts efficacy of certain cancer therapeutic agents. NVP-BEZ235 (BEZ235) is a novel, orally bioavailable dual PI3K/mTOR inhibitor that has exhibited promising activity against non-small cell lung cancer (NSCLC) in preclinical models. The current study focuses on evaluating the role of BEZ235 in regulating autophagy. BEZ235 was effective in inhibiting the growth of NSCLC cells including induction of apoptosis. It also potently induced the expression of type-II LC3, indicating induction of autophagy. When BEZ235 was used in combination with the lysosomal or autophagic inhibitor chloroquine (CQ), enhanced inhibitory effects on monolayer growth and colony formation of NSCLC cells was observed. In addition, enhanced induction of apoptosis was also detected in cells exposed to the combination of BEZ235 and CQ. Moreover, the combination of BEZ235 and CQ was more effective than each single agent alone in inhibiting the growth of NSCLC xenografts in nude mice. Thus, induction of autophagy by BEZ235 appears to be a survival mechanism that may counteract its anticancer effects. Based on these, we suggest a strategy to enhance BEZ235's anticancer efficacy by blockade of autophagy.

miR-135b Stimulates Osteosarcoma Recurrence and Lung Metastasis via Notch and Wnt/β-Catenin Signaling

Cancer stem cells (CSCs) play an important role in osteosarcoma (OS) metastasis and recurrence, and both Wnt/β-catenin and Notch signaling are essential for the development of the biological traits of CSCs. However, the mechanism that underlies the simultaneous hyperactivation of both Wnt/β-catenin and Notch signaling in OS remains unclear. Here, we report that expression of miR-135b correlates with the overall and recurrence-free survival of OS patients, and that miR-135b has an activating effect on both Wnt/β-catenin and Notch signaling. The overexpression of miR-135b simultaneously targets multiple negative regulators of the Wnt/β-catenin and Notch signaling pathways, including glycogen synthase kinase-3 beta (GSK3β), casein kinase 1a (CK1α), and ten-eleven translocation 3 (TET3). Therefore, upregulated miR-135b promotes CSC traits, lung metastasis, and tumor recurrence in OS. Notably, antagonizing miR-135b potently inhibits OS lung metastasis, cancer cell stemness, CSC-induced tumor formation, and recurrence in xenograft animal models. These findings suggest that miR-135b mediates the constitutive activation of Wnt/β-catenin and Notch signaling, and that the inhibition of miR-135b is a novel strategy to inhibit tumor metastasis and prevent CSC-induced recurrence in OS.

MiR-34c inhibits osteosarcoma metastasis and chemoresistance

Studies have shown that miR-34c is associated with metastasis and the chemoresponse of several cancers, but its role in osteosarcoma (OS) is unclear. Here, we investigated the role and mechanism of miR-34c in OS metastasis and chemoresponse. In this study, we found that the expression of miR-34c was significantly decreased in specimens from OS patients with a poor chemoresponse or metastasis compared to those with a good chemoresponse and no metastasis. The inhibition of miR-34c significantly stimulated OS cell invasion and chemoresistance in vitro. In contrast, restoring miR-34c significantly inhibited OS cell invasion and chemoresistance. Furthermore, we identified Notch1 and lymphoid enhancer-binding factor 1 (LEF1) as target genes of miR-34c in OS cells and demonstrated that Notch1 and LEF1 have a major role in the effects of miR-34c on OS cell chemosensitivity and metastasis. Taken together, our data indicate that miR-34c suppresses OS metastasis and chemoresistance by targeting Notch1 and LEF1. Restoring miR-34c may have important implications for the development of strategies for inhibiting metastasis and overcoming OS cell resistance to chemotherapy.

Decreased expression of miR216a contributes to non-small-cell lung cancer progression

PURPOSE

The aim of the present study is to investigate the role and mechanism of miR216a in non-small-cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

The expression of miR216a in NSCLC cell lines and from NSCLC patient specimens was measured by real-time qRT-PCR. The correlation between gene expression and patient survival was analyzed using Kaplan-Meier methods. The effects of miR216a on NSCLC cell growth and metastasis were examined both in vitro and in vivo by overexpressing or inhibiting miR216a. Finally, the effect of miR216a on chemoresistance was investigated by MTT assay and flow cytometry.

RESULTS

miR216a expression was downregulated in specimens from patients with NSCLC compared with corresponding nontumor lung tissues. Clinical data indicate that decreased miR216a expression is inversely correlated with cancer stage, metastasis, and poor survival in patients with NSCLC. Our data also show that overexpression of miR216a suppresses NSCLC cell growth and metastasis, and enhances cisplatin-induced cell growth inhibition and apoptosis. In contrast, inhibition of miR216a stimulates NSCLC cell growth and metastasis, and suppresses cisplatin-induced cell growth inhibition and apoptosis. Furthermore, we demonstrate that miR216a exerts its role by directly targeting eIF4B and ZEB1.

CONCLUSION

Our findings suggest that miR216a is a cancer suppressor miRNA and that overexpression of miR216a is a novel NSCLC treatment strategy. In addition, our clinical data indicate that miR216a may be a useful biomarker for predicting NSCLC progression.

Growth mechanism of tubular ZnO formed in aqueous solution

Tubular ZnO microstructural arrays were fabricated by a hydrothermal decomposition method. The dependence of the morphologies on the growth time and temperature was investigated in detail. An experiment was carried out to determine the mechanism of tubular ZnO formation. Our results showed that ZnO microtubes originated from an ageing process from ZnO microrods at a lower temperature (compared to the temperature when hydrothermal deposition of ZnO microrods was dominant) due to the preferential chemical dissolution of the metastable Zn-rich (0001) polar surfaces. A growth model was proposed based on the coexistence of hydrothermal deposition and dissolution of ZnO in the fabrication process.

Stromal colonies from mouse marrow: characterization of cell types, optimization of plating efficiency and its effect on radiosensitivity

Modifications to the colony assay in vitro for stromal progenitor cells in mouse femoral marrow have been studied so as to optimize the efficiency of colony formation (CFE). The highest reproducible concentration achieved was about 30 colonies (containing fibroblasts, macrophages and endothelioid cells) per 10(6) nucleated marrow cells (range 20–50) in mice 3–4 months old, and higher by 50% in mice 14–15 months old. Each of many slight technical modifications could reduce these values by more than 30%. The importance of optimization was demonstrated by a reduced radiosensitivity when the CFE was reduced by a factor of 3 using alpha-medium stored at 4 degrees C for 15 days. The D0 value was 3.9 +/− 0.8 Gy compared to 1.6 +/− 0.1 Gy using freshly prepared medium, and this could be due to the selection of a radioresistant subpopulation. The modifications studied may partly explain the marked variations in CFE and in radiosensitivity reported in the literature.

Effects of endostar combined multidrug chemotherapy in osteosarcoma

Angiogenesis is closely related to tumor development and metastasis. Osteosarcoma is an angiogenesis-dependent tumor, and studies have shown that chemotherapy often induces angiogenesis. Endostatin is a broad spectrum angiogenesis inhibitor and, while pre-clinical trials have shown that the combination of endostatin with chemotherapy can enhance anti-tumor effects, this effect has not yet been shown in clinical trials. Here, we aimed to evaluate the clinical efficacy of endostar (ES, human recombinant endostatin) combined with chemotherapy in the treatment of osteosarcoma patients. A total of 116 newly diagnosed patients with osteosarcoma were enrolled in this study. All patients received 4cycles of chemotherapy with (54 cases) or without (62 cases) ES. ES was administered intravenously at a dose of 15mg/day for 2weeks during each cycle of chemotherapy. The tumors were removed by surgery after 2cycles of chemotherapy treatment, and their histologic response to chemotherapy was evaluated. Immunohistochemistry was used to measure VEGF and CD 31 expression. Chemotherapy increased VEGF expression and the presence of microvessels in osteosarcoma tissues compared with pre-chemotherapy. No significant difference was observed in the histologic response between the ES treatment and non-treatment groups. However, ES treatment significantly inhibited the chemotherapy-induced VEGF expression and presence of microvessels. The ES treatment did not affect the overall survival rate but did increase the event-free survival rate and decreased the occurrence of metastases. In conclusion, our results indicate that antiangiogenic therapy using ES has the potential to prevent the progression of metastases.

High dietary inorganic phosphate affects lung through altering protein translation, cell cycle, and angiogenesis in developing mice

Inorganic phosphate (Pi) plays a key role in diverse physiological functions. Several studies indicate that Pi may affect lung cell development through Na/Pi cotransporter (NPT). Several NPT subtypes have been identified in mammalian lung, and considerable progress has been made in our understanding of their function and regulation. Therefore, current study was performed to elucidate the potential effects of high dietary Pi on lungs of developing mice. Our results clearly demonstrate that high dietary Pi may affect the lung of developing mice through Akt-related cap-dependent protein translation, cell cycle regulation, and angiogenesis. Our results support the hypothesis that Pi works as a critical signal molecule for normal lung growth and suggest that careful restriction of Pi consumption may be important in maintaining a normal development.

Inhaled fluorescent magnetic nanoparticles induced extramedullary hematopoiesis in the spleen of mice

OBJECTIVES

Nanomaterials are used in a wide variety of industrial materials such as semiconductors, magnetic resonance imaging, gene delivery carriers for gene therapy and many others; thus, human seems to be frequently exposed to them. Such diverse applications of nanoparticles elicit the need to identify the positive aspects of nanomaterials while avoiding the potential toxic effects. In this study, inhalation toxicity of manufactured nanomaterials using fluorescent magnetic nanoparticles (FMNPs) was assessed to address the issue of potential nanoparticle toxicity.

METHODS

Biological samples from a previous mouse FMNP exposure experiment were analyzed for potential FMNP toxicity. Mice inhaled FMNPs for 4 wk through a nose-only exposure chamber developed by our group for 4 wk and the potential toxicity of FMNPs was analyzed.

RESULTS

The nanoparticle distribution by scanning mobility particle sizer (SMPS) analysis showed that the mean values of number concentration (mass concentrations) in the nose-only exposure chamber were maintained at 4.89 x 10(5)/cm3 (approximately 159.4 microg/m3) for the low concentration and 9.34 x 10(5)/cm3 (approximately 319.5 microg/m3) for the high concentration, respectively. Inhalation of FMNPs caused a decrease of body weight and significant changes of white blood cells (WBCs) levels in whole blood. The FMNPs induced extramedullary hematopoiesis in the spleen without having a pulmonary effect.

CONCLUSIONS

Our results support the proposition that extensive toxicity evaluation is needed for practical applications of anthropogenic nanomaterials and suggest that careful regulation of nanoparticle applications may be necessary to maintain a high quality of life as well as for facilitating the development of nanotechnology.

IKBKE Is a Substrate of EGFR and a Therapeutic Target in Non-Small Cell Lung Cancer with Activating Mutations of EGFR

Non-small cell lung cancers (NSCLC) marked by EGFR mutations tend to develop resistance to therapeutic EGFR inhibitors, often due to secondary mutation EGFR(T790M) but also other mechanisms. Here we report support for a rationale to target IKBKE, an IκB kinase family member that activates the AKT and NF-κB pathways, as one strategy to address NSCLC resistant to EGFR inhibitors. While wild-type and mutant EGFR directly interacted with IKBKE, only mutant EGFR phosphorylated IKBKE on residues Y153 and Y179. The unphosphorylatable mutant IKBKE-Y153F/Y179-F that lost kinase activity failed to activate AKT and inhibited EGFR signaling. In clinical specimens of NSCLC with activating mutations of EGFR, we observed elevated levels of phospho-Y153 IKBKE. IKBKE ablation with shRNA or small-molecule inhibitor amlexanox selectively inhibited the viability of NSCLC cells with EGFR mutations in vitro In parallel, we found that these treatments activated the MAPK pathway due to attenuation of an IKBKE feedback mechanism. In vivo studies revealed that combining amlexanox with MEK inhibitor AZD6244 significantly inhibited the xenograft tumor growth of NSCLC cells harboring activating EGFR mutations, including EGFR(T790M) Overall, our findings define IKBKE as a direct effector target of EGFR and provide a therapeutic rationale to target IKBKE as a strategy to eradicate EGFR-TKI-resistant NSCLC cells. Cancer Res; 76(15); 4418-29. ©2016 AACR.

miR-424 acts as a tumor radiosensitizer by targeting aprataxin in cervical cancer

Previous studies have shown that some dysregulated miRNAs are involved in radioresistance of tumor cells. Here, we identified significantly decreased miR-424 expression in radioresistant cervical cancer cells and specimens from cervical cancer patients with radioresistance compared to their radiosensitive parental cells and specimens from radiosensitive patients, respectively. Ectopic expression of miR-424 significantly increased radiation-induced DNA damage, cell apoptosis and G2/M cell cycle arrest in radioresistant cervical cancer cells. Notably, miR-424 agomiR treatment can sensitize radioresistant cervical cancer cells to radiation in a xenograft model. Furthermore, we demonstrated that miR-424 regulated radiosensitivity by directly targeting aprataxin. Taken together, these findings suggest that miR-424 acts as a radiosensitizing miRNA and reveal a new therapeutic strategy for radioresistant cervical cancers.

Genistein promotes ionizing radiation-induced cell death by reducing cytoplasmic Bcl-xL levels in non-small cell lung cancer

Genistein (GEN) has been previously reported to enhance the radiosensitivity of cancer cells; however, the detailed mechanisms remain unclear. Here, we report that GEN treatment inhibits the cytoplasmic distribution of Bcl-xL and increases nuclear Bcl-xL in non-small cell lung cancer (NSCLC). Interestingly, our in vitro data show that ionizing radiation IR treatment significantly increases IR-induced DNA damage and apoptosis in a low cytoplasmic Bcl-xL NSCLC cell line compared to that of high cytoplasmic Bcl-xL cell lines. In addition, clinical data also show that the level of cytoplasmic Bcl-xL was negatively associated with radiosensitivity in NSCLC. Furthermore, we demonstrated that GEN treatment enhanced the radiosensitivity of NSCLC cells partially due to increases in Beclin-1-mediated autophagy by promoting the dissociation of Bcl-xL and Beclin-1. Taken together, these findings suggest that GEN can significantly enhance radiosensitivity by increasing apoptosis and autophagy due to inhibition of cytoplasmic Bcl-xL distribution and the interaction of Bcl-xL and Beclin-1 in NSCLC cells, respectively.

KRASQ61H Preferentially Signals through MAPK in a RAF Dimer-Dependent Manner in Non-Small Cell Lung Cancer

Assembly of RAS molecules into complexes at the cell membrane is critical for RAS signaling. We previously showed that oncogenic KRAS codon 61 mutations increase its affinity for RAF, raising the possibility that KRAS^Q61H, the most common KRAS mutation at codon 61, upregulates RAS signaling through mechanisms at the level of RAS assemblies. We show here that KRAS^Q61H exhibits preferential binding to RAF relative to PI3K in cells, leading to enhanced MAPK signaling in in vitro models and human NSCLC tumors. X-ray crystallography of KRAS^Q61H:GTP revealed that a hyperdynamic switch 2 allows for a more stable interaction with switch 1, suggesting that enhanced RAF activity arises from a combination of absent intrinsic GTP hydrolysis activity and increased affinity for RAF. Disruption of KRAS^Q61H assemblies by the RAS oligomer-disrupting D154Q mutation impaired RAF dimerization and altered MAPK signaling but had little effect on PI3K signaling. However, KRAS^Q61H oligomers but not KRAS^G12D oligomers were disrupted by RAF mutations that disrupt RAF-RAF interactions. KRAS^Q61H cells show enhanced sensitivity to RAF and MEK inhibitors individually, whereas combined treatment elicited synergistic growth inhibition. Furthermore, KRAS^Q61H tumors in mice exhibited high vulnerability to MEK inhibitor, consistent with cooperativity between KRAS^Q61H and RAF oligomerization and dependence on MAPK signaling. These findings support the notion that KRAS^Q61H and functionally similar mutations may serve as predictive biomarkers for targeted therapies against the MAPK pathway. SIGNIFICANCE: These findings show that oncogenic KRAS^Q61H forms a cooperative RAS-RAF ternary complex, which renders RAS-driven tumors vulnerable to MEKi and RAFi, thus establishing a framework for evaluating RAS biomarker-driven targeted therapies.

A cellular analysis of residual hemopoietic deficiencies in mice after 4 repeated doses of 4.5 Gray X rays

A sub-optimal plateau in numbers of femoral stem-cells (CFU-S) in mice after 4 doses of 4.5 Gray X rays (each separated by 21 days), was shown to persist at 20-30% of control up to 1 year after the last dose, when about 50% of the mice had survived. The concentration of white cells in the blood was maintained persistently at about 70% of control, whereas the concentration of red cells was normal up to 4 months and then it declined to about 75% of control at 10 months after irradiation. Concentrations of some committed progenitor cells in the marrow (GM-CFC and ERC), which are capable of amplification cell divisions, were intermediate between the concentrations of marrow stem cells and mature blood cells in both the granuloid and the erythroid cell lineages, respectively. Hence increased amplification was a mechanism operating for a prolonged period in the production of numbers of mature cells. The numbers were subnormal, however, and this corresponded to only 1 extra amplification division on average. There was a slow decline after 6 months in the numbers of CFU-S, BFU-E and GM-CFC, and in the hematocrit, with reference to age-matched controls. The decline was due partly to a prevention of the natural increase in cell numbers in the marrow with the age of the mice, which was also seen with the femoral content of a stromal progenitor cell (CFU-F). A defect in the repeatedly-irradiated CFU-S population was detected as a persistent inability to produce colonies containing the same number of daughter CFU-S as contained in colonies derived from unirradiated marrow and assayed at the same time.