Proteasome inhibitor MG132 enhances the antigrowth and antimetastasis effects of radiation in human nonsmall cell lung cancer cells

The multifaceted roles of matrix metalloproteinases in lung cancer

Background

Though the matrix metalloproteinases (MMPs) are widely investigated in lung cancer (LC), however, almost no review systematically clarify their multi-faced roles in LC.

Methods

We investigated the expression of MMPs and their effects on survival of patients with LC, the resistance mechanisms of MMPs in anti-tumor therapy, the regulatory networks of MMPs involved, the function of MMPs inducing CSCLs, MMPs-related tumor immunity, and effects of MMP polymorphisms on risk of LC.

Results

High expression of MMPs was mainly related to poor survival, high clinical stages and cancer metastasis. Role of MMPs in LC are multi-faced. MMPs are involved in drug resistance, induced CSCLs, participated in tumor immunity. Besides, MMPs polymorphisms may increase risk of LC.

Conclusions

MMPs might be promising targets to restore the anti-tumor immune response and enhance the killing function of nature immune cells in LC.

LncRNA DLGAP1-AS2 promotes the radioresistance of rectal cancer stem cells by upregulating CD151 expression via E2F1

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DLGAP1-AS2 knockdown inhibits radioresistance of rectal cancer stem cells.

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DLGAP1-AS2 elevates CD151 expression via interactions with E2F1.

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DLGAP1-AS2 facilitates radioresistance of rectal cancer by interacting with E2F1 to upregulate CD151 expression.

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DLGAP1-AS2 promotes radioresistance of rectal cancer via modulating E2F1 to elevate CD151 expression through activating AKT/mTOR/cyclinD1 signaling.

Background

Radiotherapy resistance is one of the major causes of rectal cancer treatment failure. LncRNA DLGAP1-AS2 participates in the progression of several cancers. We explored the role and potential mechanism of DLGAP1-AS2 in the radioresistance of rectal cancer stem cells.

Methods

HR8348-R cells, radioresistant cells from HR8348 after irradiation, were isolated into CD133 negative (CD133⁻) and positive (CD133⁺) cells. Cell proliferation, apoptosis, migration and tumorsphere formation were determined by CCK-8, flow cytometry, wound healing assay and tumorsphere formation assay, respectively. CD133, tumor stem cell drug resistance gene (MDR1 and BCRP1), DNA repair marker (γ-H2AX) and AKT/mTOR/cyclinD1 signaling were measured by Western blot. The relationship between DLGAP1-AS2 and E2F1 was verified using RIP. The interaction between E2F1 and CD151 promoter was confirmed using dual-luciferase reporter gene assay and ChIP. AKT inhibitor API-2 was employed for validating the effect of AKT/mTOR/cyclinD1 signaling in the radioresistance of rectal cancer cells.

Results

The DLGAP1-AS2 level was increased in CD133⁺ cells after irradiation. DLGAP1-AS2 knockdown inhibited the proliferation, migration and tumorsphere formation while stimulating apoptosis in CD133⁺ cells. DLGAP1-AS2 inhibition downregulated the expression of CD133, MDR1, BCRP1 and γ-H2AX and suppressed AKT/mTOR/cyclinD1 activation. DLGAP1-AS2 upregulated the expression of CD151 by interacting with E2F1. API-2 neutralized the promotive effects of overexpressed CD151 on radioresistance.

Conclusion

DLGAP1-AS2 accelerates the radioresistance of rectal cancer cells through interactions with E2F1 to upregulate CD151 expression via the activation of the AKT/mTOR/cyclinD1 pathway.

Identification and Validation of an Immune and Ferroptosis-Combined Index for Non-Small Cell Lung Cancer

Background: Non-small cell lung cancer (NSCLC) is among the major health problems around the world. Reliable biomarkers for NSCLC are still needed in clinical practice. We aimed to develop a novel ferroptosis- and immune-based index for NSCLC. Methods: The training and testing datasets were obtained from TCGA and GEO databases, respectively. Immune- and ferroptosis-related genes were identified and used to establish a prognostic model. Then, the prognostic and therapeutic potential of the established index was evaluated. Results: Intimate interaction of immune genes with ferroptosis genes was observed. A total of 32 prognosis-related signatures were selected to develop a predictive model for NSCLC using LASSO Cox regression. Patients were classified into the high- and low-risk group based on the risk score. Patients in the low-risk group have better OS in contrast with that in the high-risk group in independent verification datasets. Besides, patients with a high risk score have shorter OS in all subgroups (T, N, and M0 subgroups) and pathological stages (stage I, II, and III). The risk score was positively associated with Immune Score, Stromal Score, and Ferroptosis Score in TCGA and GEO cohorts. A differential immune cell infiltration between the high-risk and the low-risk groups was also observed. Finally, we explored the significance of our model in tumor-related pathways, and different enrichment levels in the therapeutic pathway were observed between the high- and low-risk groups. Conclusion: The present study developed an immune and ferroptosis-combined index for the prognosis of NSCLC.

Quercetin radiosensitizes non-small cell lung cancer cells through the regulation of miR-16-5p/WEE1 axis

BACKGROUND

Quercetin, a widely distributed bioflavonoid, plays a role in combating diverse human cancers including non-small cell lung cancer (NSCLC). However, the role of quercetin in reversing the radioresistance of NSCLC cells and its underlying mechanism are far from being elucidated.

METHOD

Radiation-resistant NSCLC cell lines were established. Quantitative real-time PCR (qRT-PCR) was used to detect the expression of miR-16-5p and WEE1 G2 checkpoint kinase (WEE1) mRNA in radiation-resistant cells. After being treated with different concentrations of quercetin and different doses of X-ray, cell proliferation and apoptosis were monitored by CCK-8 assay, colony formation assay, and flow cytometry, respectively. Ultimately, the targeting relationship between miR-16-5p and WEE1 was verified via a dual fluorescent reporter gene assay.

RESULTS

The expression of miR-16-5p was down-regulated in radiation-resistant cells, while the expression of WEE1 was up-regulated. Quercetin enhanced the radiosensitivity of NSCLC cells in a dose- and time-dependent manner. Furthermore, quercetin treatment increased the expression of miR-16-5p and decreased the expression of WEE1. The function of quercetin was reversed by miR-16-5p inhibitors or the transfection of WEE1 overexpressing plasmids.

CONCLUSION

In conclusion, quercetin enhanced the radiosensitivity of NSCLC cells via modulating the expression of miR-16-5p and WEE1.

MG132 selectively upregulates MICB through the DNA damage response pathway in A549 cells

Natural killer (NK) cells recognize stress-activated NK group 2, member D (NKG2D) ligands in tumors. In the present study, the expression levels of NKG2D ligands were examined in four lung cancer cell lines (A549, PLA801D, NCI-H157 and NCI-H520). In the A549 cells, the expression of MHC class I polypeptiderelated sequence (MIC)A/B and UL16 binding protein (ULBP)1 was weak, the expression of ULBP2 was typical, and neither ULBP3 nor ULBP4 were expressed. The mechanism underlying the regulatory effect of a cancer treatment agent on the expression of NKG2D ligands was investigated using the proteasome inhibitor MG132. Following treatment for 8 h with MG132, the transcription levels of MICB and ULBP1 were upregulated 10.62- and 11.09-fold, respectively, and the expression levels of MICB and ULBP1 were increased by 68.18 and 23.65%, respectively. Notably, MICB exhibited significant time-dependent change. MG132 increased the transcription of MICB by acting at a site in the 480-bp MICB upstream promoter. The activity of the MICB promoter was upregulated 1.77-fold following treatment with MG132. MG132 treatment improved the cytotoxicity of NK cells, which was partially blocked by an antibody targeting NKG2D, and more specifically the MICB molecule. The expression of MICB induced by MG132 was inhibited by KU-55933 [ataxia telangiectasia mutated (ATM) kinase inhibitor], wortmannin (phosphoinositide 3 kinase inhibitor) and caffeine (ATM/ATM-Rad3-related inhibitor). The phosphorylation of checkpoint kinase 2 (Chk2), an event associated with DNA damage, was observed following treatment with MG132. These results indicated that MG132 selectively upregulates the expression of MICB in A549 cells, and increases the NKG2D-mediated cytotoxicity of NK cells. The regulatory effect of MG132 may be associated with the activation of Chk2, an event associated with DNA damage. The combination of MG132 with NK cell immunotherapy may have a synergistic effect that improves the therapeutic effect of lung cancer treatment.

Effects of radiation on the metastatic process

Radiotherapy remains one of the corner stones in the treatment of various malignancies and often leads to an improvement in overall survival. Nonetheless, pre-clinical evidence indicates that radiation can entail pro-metastatic effects via multiple pathways. Via direct actions on cancer cells and indirect actions on the tumor microenvironment, radiation has the potential to enhance epithelial-to-mesenchymal transition, invasion, migration, angiogenesis and metastasis. However, the data remains ambiguous and clinical observations that unequivocally prove these findings are lacking. In this review we discuss the pre-clinical and clinical data on the local and systemic effect of irradiation on the metastatic process with an emphasis on the molecular pathways involved.

DNA methylation enzyme inhibitor RG108 suppresses the radioresistance of esophageal cancer

Esophageal cancer (EC) is the eighth most common highly aggressive cancer worldwide. The purpose of this study was to investigate the effect of the DNA methyltransferase inhibitor RG108 on the radiosensitivity of EC cells. MTT and clonogenic assays were performed to assess the effect of RG108 on the proliferation and radiosensitivity of Eca-109 and TE-1 human EC cells. The cell cycle progression and alterations in apoptosis were analyzed by flow cytometry. For the in vivo analysis, the Eca-109 cells were inoculated into nude mice to establish tumors. Tissues from xenografts were obtained to detect changes to microvessels and tumor growth by immunohistochemistry (IHC). RNA-seq was used to identify differentially expressed genes. We found that RG108 increased the radiosensitivity of EC cells. Apoptosis and G2/M-phase arrest were induced by X-ray irradiation and were significantly enhanced by RG108. In addition, growth of tumor xenografts from the Eca-109 cells was significantly inhibited by irradiation in combination with RG108. The RNA-seq analysis revealed that, compared with radiation alone, X-ray irradiation in combination with RG108 altered the expression of 121 genes in multiple pathways, including the TGF-β signaling pathway and the Epstein-Barr virus infection pathway. In conclusion, RG108 induced radiosensitivity in EC cells both in vitro and in vivo.

Proteomic Profiling of Radiation-Induced Skin Fibrosis in Rats: Targeting the Ubiquitin-Proteasome System

PURPOSE

To investigate the molecular changes underlying the pathogenesis of radiation-induced skin fibrosis.

METHODS AND MATERIALS

Rat skin was irradiated to 30 or 45 Gy with an electron beam. Protein expression in fibrotic rat skin and adjacent normal tissues was quantified by label-free protein quantitation. Human skin cells HaCaT and WS-1 were treated by x-ray irradiation, and the proteasome activity was determined with a fluorescent probe. The effect of proteasome inhibitors on Transforming growth factor Beta (TGF-B) signaling was measured by Western blot and immunofluorescence. The efficacy of bortezomib in wound healing of rat skin was assessed by the skin injury scale.

RESULTS

We found that irradiation induced epidermal and dermal hyperplasia in rat and human skin. One hundred ninety-six preferentially expressed and 80 unique proteins in the irradiated fibrotic skin were identified. Through bioinformatic analysis, the ubiquitin-proteasome pathway showed a significant fold change and was investigated in greater detail. In vitro experiments demonstrated that irradiation resulted in a decline in the activity of the proteasome in human skin cells. The proteasome inhibitor bortezomib suppressed profibrotic TGF-β downstream signaling but not TGF-β secretion stimulated by irradiation in HaCaT and WS-1 cells. Moreover, bortezomib ameliorated radiation-induced skin injury and attenuated epidermal hyperplasia.

CONCLUSION

Our findings illustrate the molecular changes during radiation-induced skin fibrosis and suggest that targeting the ubiquitin-proteasome system would be an effective countermeasure.

miR-16 induction after CDK4 knockdown is mediated by c-Myc suppression and inhibits cell growth as well as sensitizes nasopharyngeal carcinoma cells to chemotherapy

Cyclin-dependent kinase 4 (CDK4) is a member of cyclin-dependent kinase family which regulates G1 to S cell cycle transition. CDK4 activity is increased in many tumor types. Here, we report a negative automodulatory feedback loop between CDK4 and miR-16 that regulates cell cycle progression in nasopharyngeal carcinoma (NPC). By miRNA array and real-time PCR, we identified upregulation of tumor suppressor miR-16a, which inhibited cell cycle progression and sensitized NPC cells to chemotherapy. CDK4 knockdown reduced the expression of c-Myc, the latter of which directly suppresses the miR-16 expression by directly binding to the miR-16 promoter. Moreover, we found that miR-16 upregulation could reduce CDK4 expression by repressing CCND1 and thus forms a feedback loop via the CDK4/c-Myc/miR-16/CCND1 pathway. Finally, miR-16 was negatively correlated with CDK4 expression in NPC biopsies. In summary, our results define a double-negative feedback loop involving CDK4 and miR-16 mediated by c-Myc that modulates NPC cell growth and chemotherapy sensitivity.

MG132 enhances the radiosensitivity of lung cancer cells in vitro and in vivo

Radiotherapy is a common treatment modality for lung cancer, however, radioresistance remains a fundamental barrier to attaining the maximal efficacy. Cancer cells take advantage of the ubiquitin-proteasome system (UPS) for increased proliferation and decreased apoptotic cell death. MG132 (carbobenzoxyl-leucinyl-leucinyl-leucinal‑H), a specific and selective reversible inhibitor of the 26S proteasome, has shown anticancer effect in multiple types of cancers. Previously, we have reported that MG132 enhances the anti‑growth and anti-metastatic effects of irradiation in lung cancer cells. However, whether MG132 can enhance the radiosensitivity in lung cancer cells in vitro and in vivo is still unknown. In this study, we found that MG132 increased apoptosis and dicentric chromosome ratio of A549 and H1299 cells treated by irradiation. Radiation-induced NF-κB expression and IκBα phosphorylation was attenuated in MG132 plus irradiation-treated cells. The in vivo model of H1299 xenografts of nude mice showed that the tumor size of MG132 plus irradiation treated xenografts was smaller than that of irradiation, MG132 or the control group. Moreover, MG132 plus irradiation group showed significant reduced Ki67 expression. Taken together, these results demonstrate that MG132 enhances the radiosensitivity through multiple mechanisms in vitro and in vivo.

Shikonin inhibits the cell viability, adhesion, invasion and migration of the human gastric cancer cell line MGC-803 via the Toll-like receptor 2/nuclear factor-kappa B pathway

OBJECTIVES

Shikonin is an active naphthoquinone pigment isolated from the root of Lithospermum erythrorhizon. This study was designed to explore the inhibition of Shikonin on cell viability, adhesion, migration and invasion ability of gastric cancer (GC) and its possible mechanism.

METHODS

3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed for cell viability and adhesion ability of MGC-803 cells. Cell scratch repair experiments were conducted for the determination of migration ability while transwell assay for cell invasion ability. Western blot analysis and real-time polymerase chain reaction assay were used for the detection of protein and mRNA expressions.

KEY FINDINGS

Fifty per cent inhibitory concentration of Shikonin on MGC-803 cells was 1.854 μm. Shikonin (1 μm) inhibited significantly the adhesion, invasion and migratory ability of MGC-803 cells. Interestingly, Shikonin in the presence or absence of anti-Toll-like receptor 2 (TLR2) antibody (2 μg) and nuclear factor-kappa B (NF-κB) inhibitor MG-132 (10 μm) could decrease these ability of MGC-803 cells markedly, as well as the expression levels of matrix metalloproteinases (MMP)-2, MMP-7, TLR2 and p65 NF-κB. In addition, the co-incubation of Shikonin and anti-TLR2/MG-132 has a significant stronger activity than anti-TLR2 or MG-132 alone.

CONCLUSIONS

The results indicated that Shikonin could suppress the cell viability, adhesion, invasion and migratory ability of MGC-803 cells through TLR2- or NF-κB-mediated pathway. Our findings provide novel information for the treatment of Shikonin on GC.

Radiation oncology in vitro: trends to improve radiotherapy through molecular targets

Much has been investigated to improve the beneficial effects of radiotherapy especially in that case where radioresistant behavior is observed. Beyond simple identification of resistant phenotype the discovery and development of specific molecular targets have demonstrated therapeutic potential in cancer treatment including radiotherapy. Alterations on transduction signaling pathway related with MAPK cascade are the main axis in cancer cellular proliferation even as cell migration and invasiveness in irradiated tumor cell lines; then, for that reason, more studies are in course focusing on, among others, DNA damage enhancement, apoptosis stimulation, and growth factors receptor blockages, showing promising in vitro results highlighting molecular targets associated with ionizing radiation as a new radiotherapy strategy to improve clinical outcome. In this review we discuss some of the main molecular targets related with tumor cell proliferation and migration as well as their potential contributions to radiation oncology improvements.