Cathepsin L activated by mutant p53 and Egr-1 promotes ionizing radiation-induced EMT in human NSCLC

USP9X inhibits metastasis in pulmonary sarcomatoid carcinoma by regulating epithelial-mesenchymal transition, angiogenesis and immune infiltration

BACKGROUND

Pulmonary sarcomatoid carcinoma (PSC) is a highly invasive pulmonary malignancy with an extremely poor prognosis. The results of previous studies suggest that ubiquitin-specific peptidase 9X (USP9X) contributes to the progression of numerous types of cancer. Nevertheless, there is little knowledge about the molecular mechanisms and functions of USP9X in the metastasis of PSC.

METHODS

Immunohistochemistry and western blotting were used to detect USP9X expression levels in PSC tissues and cells. Wound healing, transwell, enzyme-linked immunosorbent assay (ELISA), tube formation, and aortic ring assays were used to examine the function and mechanism of USP9X in the metastasis of PSC.

RESULTS

Expression of USP9X was markedly decreased and significantly correlated with metastasis and prognosis of patients with PSC. Then we revealed that USP9X protein levels were negatively associated with the levels of epithelial-mesenchymal transition (EMT) markers and the migration of PSC cells. It was confirmed that USP9X in PSC cells reduced VEGF secretion and inhibited tubule formation of human umbilical vein endothelial cells (HUVEC) in vitro. USP9X was detected to downregulate MMP9. Meanwhile, MMP9 was positively related to EMT, angiogenesis and was negatively related to immune infiltration in the public databases. USP9X was significantly negatively associated with the expression of MMP9, EMT markers, CD31, and positively associated with CD4, and CD8 in PSC tissues.

CONCLUSION

The present study reveals the vital role of USP9X in regulating EMT, angiogenesis and immune infiltration and inhibiting metastasis of PSC via downregulating MMP9, which provides a new effective therapeutic target for PSC.

Mutant p53 achieves function by regulating EGR1 to induce epithelial mesenchymal transition

The epithelial-mesenchymal transition (EMT) plays a crucial role in lung cancer metastasis, rendering it a promising therapeutic target. Research has shown that non-small cell lung cancer (NSCLC) with p53 mutations exhibits an increased tendency for cancer metastasis. However, the exact contribution of the p53-R273H mutation to tumor metastasis remains uncertain in the current literature. Our study established the H1299-p53-R273H cell model successfully by transfecting the p53-R273H plasmid into H1299 cells. We observed that p53-R273H promotes cell proliferation, migration, invasion, and EMT through CCK-8, wound healing, transwell, western blot and immunofluorescence assays. Notably, the expression of EGR1 was increased in H1299-p53-R273H cells. Knocking out EGR1 in these cells hindered the progression of EMT. ChIP-PCR experiments revealed that p53-R273H binds to the EGR1 promoter sequence, thereby regulating its expression. These findings suggest that p53-R273H triggers EMT by activating EGR1, thereby offering a potential therapeutic approach for lung cancer treatment.

Circ-10720 as a ceRNA adsorbs microRNA-1238 and modulates ZEB2 to boost NSCLC development by activating EMT

BACKGROUND

Circular RNAs (circRNAs) are critical regulators in the progression of tumors. This experimental design aimed to explore the mechanism of circ-10720 in non-small cell lung cancer (NSCLC).

METHODS

We used RT-qPCR to measure circ-10720 expression in clinical samples and analyzed its relationship with the clinicopathological characteristics of NSCLC patients. The expression levels of microRNA-1238 (miR-1238) and Zinc Finger E-box-binding Homeobox 2 (ZEB2) in clinical samples were detected by RT-qPCR. NSCLC cells were transfected with relevant plasmids or sequences. Circ-10720, miR-1238, and ZEB2 expressions in cells were analyzed via RT-qPCR or western blot. Cell proliferation, apoptosis, migration, and invasion were assessed with CCK-8, flow cytometry, and transwell assay, respectively. The protein expression of ZEB2 and epithelial-mesenchymal transition (EMT)-related markers (E-cadherin, Vimentin, N-cadherin) were detected via western blot. Xenograft assay was used to determine the effect of circ-10720 on NSCLC in vivo. Circ-10720 and ZEB2 expressions in tumors were detected using RT-qPCR or Western blot. Immunohistochemistry was used to evaluate E-cadherin and N-cadherin expression in tumors. Finally, the binding relationship between miR-1238 with circ-10720 or ZEB2 was verified by the bioinformatics website, dual luciferase reporter assay, RNA pull-down assay, and RIP assay.

RESULTS

Circ-10720 was upregulated in NSCLC and correlated with TNM stage of NSCLC patients. MiR-1238 was lowly expressed but ZEB2 was highly expressed in NSCLC. Circ-10720 silencing suppressed the proliferation, metastasis, and EMT of NSCLC cells. Mechanically, circ-10720 was a competitive endogenous RNA (ceRNA) for miR-1238, and ZEB2 was a target of miR-1238. circ-10720-modulated ZEB2 via competitively binding with miR-1238 to control NSCLC progression. In addition, circ-10720 knockdown suppressed tumor growth in vivo.

CONCLUSIONS

Circ-10720 acts as a ceRNA to adsorb miR-1238 and modulate ZEB2 to facilitate the proliferation, migration, invasion, and EMT of NSCLC cells.

Mitochondria-related chemoradiotherapy resistance genes-based machine learning model associated with immune cell infiltration on the prognosis of esophageal cancer and its value in pan-cancer

Esophageal cancer, known for its high incidence and low five-year survival rate, poses significant treatment challenges. A key aspect of this challenge is the close link between mitochondria and resistance to chemoradiotherapy (CRT). Currently, there is a scarcity of biomarkers for predicting CRT response and prognosis in esophageal cancer. Our study addresses this gap by developing a prognostic model that incorporates mitochondria-related CRT resistance (MRCRTR) genes, including CTSL, TBL1X, CLN8, MMP1, PDPN, and MRPL37. Survival analysis using Kaplan-Meier curves reveals that patients with high MRCRTR scores have lower survival rates than those with low scores. Utilizing a nomogram, we successfully predict the one-, two-, and three-year overall survival rates for esophageal cancer patients. Cox regression analysis confirms the MRCRTR score as an independent prognostic factor. Furthermore, our single-cell and correlation analyses suggested that MRCRTR genes might influence CRT resistance by modulating the immune microenvironment and impacting angiogenesis. Our pan-cancer analysis also indicates the potential applicability of MRCRTR scores to head and neck squamous cell carcinoma. The validation of these findings, conducted with samples from Xiang-ya Hospital, aligns closely with our bioinformatics results. Our study not only explores the role of MRCRTR genes in predicting the prognosis of esophageal cancer but also enhances the understanding of the interplay between CRT, mitochondria, and patient outcomes.

Tumor-mesothelium HOXA11-PDGF BB/TGF β1-miR-181a-5p-Egr1 feedforward amplifier circuity propels mesothelial fibrosis and peritoneal metastasis of gastric cancer

A proportion of gastric cancer (GC) patients suffer from peritoneal metastasis (PM) in the late stage of tumor and these patients have a poor prognosis. To provide more care for GC patient with PM, a deeper exploration of the molecular characteristics of GC-PM is needed. Here we performed the in vitro and in vivo study to illustrate the effect of HOXA11 over-expressed GC cells on peritoneal mesothelial cells (HMrSV5), transcriptomics analyses of HMrSV5 cells co-cultured with HOXA11 over-expressed GC cells, counterparts or alone, cytokine array analyses of serum-free culture medium of HOXA11 over-expressed GC cells, we validated our findings through genetic manipulation of HMrSV5 cells and neutralizing antibodies targeting cytokines secreted by HOXA11 over-expressed GC cells in vitro, as well as utilized human peritoneal metastatic lesions to validate expression of potential targets. We identified that HOXA11 over-expressed GC cells strongly propelled mesothelial fibrosis in vivo and in vitro, and HOXA11 regulated paracrine and autocrine of PDGF BB and TGF β1 in GC cells to propel mesothelial fibrosis. Meanwhile, HOXA11 over-expressed GC cells drove PDGF BB and TGF β1 secretion to activate developmental-process related genes in HMrSV5 cells, including Egr1, which processes dependent on miR-181a-5p. Then, Egr1 could mediate peritoneal mesothelial fibrosis. Correspondingly, Egr1 over-expressed HMrSV5 cells supported migration and peritoneal dissemination of GC cells. Together our results suggest that a feedforward amplifier circuity governing GC cells and mesothelial cells in peritoneum contribute to peritoneal metastasis of GC cells.

Role of early growth response 1 in inflammation-associated lung diseases

Early growth response 1 (EGR1), which is involved in cell proliferation, differentiation, apoptosis, adhesion, migration, and immune and inflammatory responses, is a zinc finger transcription factor. EGR1 is a member of the EGR family of early response genes and can be activated by external stimuli such as neurotransmitters, cytokines, hormones, endotoxins, hypoxia, and oxidative stress. EGR1 expression is upregulated during several common respiratory diseases, such as acute lung injury/acute respiratory distress syndrome, chronic obstructive pulmonary disease, asthma, pneumonia, and novel coronavirus disease 2019. Inflammatory response is the common pathophysiological basis of these common respiratory diseases. EGR1 is highly expressed early in the disease, amplifying pathological signals from the extracellular environment and driving disease progression. Thus, EGR1 may be a target for early and effective intervention in these inflammation-associated lung diseases.

Validating a Macrophage Marker Gene Signature (MMGS) in Lung Adenocarcinoma Prognosis and Response to Immunotherapy

Lung adenocarcinoma (LUAD) is the leading cause of cancer-related death worldwide. Tumor-associated macrophages play pivotal roles in the tumor microenvironment (TME) and prognosis of LUAD. We first used single-cell RNA sequencing data to identify macrophage marker genes in LUAD. Univariate, least absolute shrinkage and selection operator and stepwise multivariate Cox regression analyses were conducted to evaluate macrophage marker genes as prognostic factors and to construct the macrophage marker genes signature (MMGS). A novel 8-gene signature was constructed to predict prognosis based on 465 macrophage marker genes identified by an analysis of single-cell RNA sequencing data of LUAD, and was also verified in 4 independent GEO cohorts. The MMGS significantly classified patients into high-risk and low-risk groups in terms of OS. A prognostic nomogram based on independent risk factors was established to predict the 2-, 3- and 5-year survival, which indicated superior accuracy in predicting prognosis. The high-risk group was correlated to higher tumor mutational burden, number of neoantigens, T-cell receptor richness, and lower TIDE, which suggested that high-risk patients were more likely to benefit from immunotherapy. The prediction of the possibility of immunotherapy efficacy was also discussed. Analysis of an immunotherapy cohort further verified that patients with high-risk scores had better immunotherapy responses than low-risk patients. The MMGS is a promising signature for predicting prognosis and effectiveness of immunotherapy in patients with LUAD, and may be helpful for clinical decision-making.

EGR1 induces EMT in pancreatic cancer via a P300/SNAI2 pathway

BACKGROUND

The prognosis of pancreatic cancer patients remains relatively poor. Although some patients would receive surgical resection, distant metastasis frequently occurs within one year. Epithelial-mesenchymal transition (EMT), as a pathological mechanism in cancer progression, contributed to the local and distant metastasis of pancreatic cancer.

METHODS

Tissue microarray analysis and immunohistochemistry assays were used to compare the expression of EGR1 in pancreatic cancer and normal pancreatic tissues. Transwell chambers were used to evaluated the migration and invasion ability of cancer cells. Immunofluorescence was utilized to assess the expression of E-cadherin. ChIP-qPCR assay was applied to verify the combination of EGR1 and SNAI2 promoter sequences. Dual-luciferase reporter assay was used to detect the gene promoter activation. Co-IP assay was conducted to verify the interaction of EGR1 and p300/CBP.

RESULTS

EGR1 was highly expressed in pancreatic cancer rather than normal pancreatic tissues and correlated with poor prognosis and cancer metastasis. EGR1 was proved to enhance the migration and invasion ability of pancreatic cells. Besides, EGR1 was positively correlated with EMT process in pancreatic cancer, via a SNAI2-dependent pathway. P300/CBP was found to play an auxiliary role in the transcriptional activation of the SNAI2 gene by EGR1. Finally, in vivo experiments also proved that EGR1 promoted liver metastasis of pancreatic cancer.

CONCLUSION

Our findings implied the EMT-promoting effect of EGR1 in pancreatic cancer and revealed the intrinsic mechanism. Blocking the expression of EGR1 may be a new anticancer strategy for pancreatic cancer.

Effects of Fractionated Radiation Exposure on Vimentin Expression in Cervical Cancers: Analysis of Association with Cancer Stem Cell Response and Short-Term Prognosis

Elucidation of the mechanisms for the response of cancer stem cells (CSCs) to radiation exposure is of considerable interest for further improvement of radio- and chemoradiotherapy of cervical cancer (CC). The aim of this work is to evaluate the effects of fractionated radiation exposure on the expression of vimentin, which is one of the end-stage markers of epithelial-mesenchymal transition (EMT), and analyze its association with CSC radiation response and short-term prognosis of CC patients. The level of vimentin expression was determined in HeLa, SiHa cell lines, and scrapings from the cervix of 46 CC patients before treatment and after irradiation at a total dose of 10 Gy using real-time polymerase chain reaction (PCR) assay, flow cytometry, and fluorescence microscopy. The number of CSCs was assessed using flow cytometry. Significant correlations were shown between vimentin expression and postradiation changes in CSC numbers in both cell lines (R = 0.88, p = 0.04 for HeLa and R = 0.91, p = 0.01 for SiHa) and cervical scrapings (R = 0.45, p = 0.008). Associations were found at the level of tendency between postradiation increase in vimentin expression and unfavorable clinical outcome 3-6 months after treatment. The results clarify some of the relationships between EMT, CSCs, and therapeutic resistance that are needed to develop new strategies for cancer treatment.

Cathepsins Trigger Cell Death and Regulate Radioresistance in Glioblastoma

Treatment of glioblastoma (GBM) remains very challenging, and it is particularly important to find sensitive and specific molecular targets. In this work, we reveal the relationship between the expression of cathepsins and radioresistance in GBM. We analyzed cathepsins (cathepsin B, cathepsin D, cathepsin L, and cathepsin Z/X), which are highly associated with the radioresistance of GBM by regulating different types of cell death. Cathepsins could be potential targets for GBM treatment.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Cathepsin L promotes chemresistance to neuroblastoma by modulating serglycin

Cathepsin L (CTSL), a lysosomal acid cysteine protease, is found to play a critical role in chemosencitivity and tumor progression. However, the potential roles and molecular mechanisms of CTSL in chemoresistance in neuroblastoma (NB) are still unclear. In this study, the correlation between clinical characteristics, survival and CTSL expression were assessed in Versteeg dataset. The chemoresistant to cisplatin or doxorubicin was detected using CCK-8 assay. Western blot was employed to detect the expression of CTSL, multi-drug resistance proteins, autophagy-related proteins and apoptosis-related proteins in NB cells while knocking down CTSL. Lysosome staining was analyzed to access the expression levels of lysosomes in NB cells. The expression of apoptosis markers was analyzed with immunofluorescence. Various datasets were analyzed to find the potential protein related to CTSL. In addition, a subcutaneous tumor xenografts model in M-NSG mice was used to assess tumor response to CTSL inhibition in vivo. Based on the validation dataset (Versteeg), we confirmed that CTSL served as a prognostic marker for poor clinical outcome in NB patients. We further found that the expression level of CTSL was higher in SK-N-BE (2) cells than in IMR-32 cells. Knocking down CTSL reversed the chemoresistance in SK-N-BE (2) cells. Furthermore, combination of CTSL inhibition and chemotherapy potently blocked tumor growth in vivo. Mechanistically, CTSL promoted chemoresistance in NB cells by up-regulating multi-drug resistance protein ABCB1 and ABCG2, inhibiting the autophagy level and cell apoptpsis. Furthermore, we observed six datasets and found that Serglycin (SRGN) expression was positively associated with CTSL expresssion. CTSL could mediate chemoresistance by up-regulating SRGN expression in NB cells and SRGN expression was positively correlated with poor prognosis of NB patients. Taken together, our findings indicate that the CTSL promotes chemoresistance to cisplatin and doxorubicin by up-regulating the expression of multi-drug resistance proteins and inhibiting the autophagy level and cell apoptosis in NB cells. Thus, CTSL may be a therapeutic target for overcoming chemoresistant to cisplatin and doxorubicin in NB patients.

Roles of Major RNA Adenosine Modifications in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer malignancy worldwide and is known to have poor prognosis. The pathogenesis behind the development of HNSCC is not fully understood. Modifications on RNA are involved in many pathophysiological processes, such as tumor development and inflammation. Adenosine-related RNA modifications have shown to be linked to cancer and may play a role in cancer occurrence and development. To date, there are at least 170 different chemical RNA modifications that modify coding and non-coding RNAs (ncRNAs). These modifications affect RNA stability and transcription efficiency. In this review, we focus on the current understanding of the four major RNA adenosine modifications (N⁶-Methyladenosine, N¹-Methyladenosine, Alternative Polyadenylation Modification and A-to-I RNA editing) and their potential molecular mechanisms related to HNSCC development and progression. We also touch on how these RNA modifications affect treatment of HNSCCs.

Upregulation of ERK-EGR1-heparanase axis by HDAC inhibitors provides targets for rational therapeutic intervention in synovial sarcoma

BACKGROUND

Synovial sarcoma (SS) is an aggressive soft tissue tumor with limited therapeutic options in advanced stage. SS18-SSX fusion oncogenes, which are the hallmarks of SS, cause epigenetic rewiring involving histone deacetylases (HDACs). Promising preclinical studies supporting HDAC targeting for SS treatment were not reflected in clinical trials with HDAC inhibitor (HDACi) monotherapies. We investigated pathways implicated in SS cell response to HDACi to identify vulnerabilities exploitable in combination treatments and improve the therapeutic efficacy of HDACi-based regimens.

METHODS

Antiproliferative and proapoptotic effects of the HDACi SAHA and FK228 were examined in SS cell lines in parallel with biochemical and molecular analyses to bring out cytoprotective pathways. Treatments combining HDACi with drugs targeting HDACi-activated prosurvival pathways were tested in functional assays in vitro and in a SS orthotopic xenograft model. Molecular mechanisms underlying synergisms were investigated in SS cells through pharmacological and gene silencing approaches and validated by qRT-PCR and Western blotting.

RESULTS

SS cell response to HDACi was consistently characterized by activation of a cytoprotective and auto-sustaining axis involving ERKs, EGR1, and the β-endoglycosidase heparanase, a well recognized pleiotropic player in tumorigenesis and disease progression. HDAC inhibition was shown to upregulate heparanase by inducing expression of the positive regulator EGR1 and by hampering negative regulation by p53 through its acetylation. Interception of HDACi-induced ERK-EGR1-heparanase pathway by cell co-treatment with a MEK inhibitor (trametinib) or a heparanase inhibitor (SST0001/roneparstat) enhanced antiproliferative and pro-apoptotic effects. HDAC and heparanase inhibitors had opposite effects on histone acetylation and nuclear heparanase levels. The combination of SAHA with SST0001 prevented the upregulation of ERK-EGR1-heparanase induced by the HDACi and promoted caspase-dependent cell death. In vivo, the combined treatment with SAHA and SST0001 potentiated the antitumor efficacy against the CME-1 orthotopic SS model as compared to single agent administration.

CONCLUSIONS

The present study provides preclinical rationale and mechanistic insights into drug combinatory strategies based on the use of ERK pathway and heparanase inhibitors to improve the efficacy of HDACi-based antitumor therapies in SS. The involvement of classes of agents already clinically available, or under clinical evaluation, indicates the transferability potential of the proposed approaches.

Assessment of immune status of laryngeal squamous cell carcinoma can predict prognosis and guide treatment

BACKGROUND

In the past few years, immunotherapy has changed the way we treat solid tumors. People pay more and more attention to the immune microenvironment of laryngeal squamous cell carcinoma (LSCC). In this study, our immunotherapy research took advantage of the clinical database and focused our in-depth analysis on the tumor microenvironment (TME).

METHODS

This study evaluated the relationship between the clinical outcome and the local tissue and overall immune status in 412 patients with primary LSCC. We constructed and validated a risk model that could predict prognosis, assess immune status, identify high-risk patients, and develop personalized treatment plans through bioinformatics. In addition, through immunohistochemical analysis, we verified the differential expression of CTSL and KDM5D genes with the largest weight coefficients in the model in LSCC tissues and their influence on the prognosis and tumor-infiltrating lymphocytes (TILs).

RESULTS

We found that interstitial tumor-infiltrating lymphocytes, tumor parenchymal-infiltrating lymphocyte volume, tumor infiltrates lymphocytes of frontier invasion, and the platelet-to-lymphocyte ratio (PLR) were independent factors affecting the prognosis of patients with LSCC. A novel risk model can guide clinicians to accurately predict prognosis, identify high-risk patients, and formulate personalized treatment plans. The differential expression of genes such as CTSL and KDM5D has a significant correlation with the TILs of LSCC and the prognosis of patients.

CONCLUSION

Local and systemic inflammatory markers in patients with laryngeal squamous cell carcinoma are reliable prognostic factors. The risk model and CTSL, KDM5D gene have important potential research value.

Contribution of p53 in sensitivity to EGFR tyrosine kinase inhibitors in non-small cell lung cancer

The emergence of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) with activating EGFR mutations is a major hindrance to treatment. We investigated the effects of p53 in primary sensitivity and acquired resistance to EGFR-TKIs in NSCLC cells. Changes in sensitivity to EGFR-TKIs were determined using p53 overexpression or knockdown in cells with activating EGFR mutations. We investigated EMT-related molecules, morphologic changes, and AXL induction to elucidate mechanisms of acquired resistance to EGFR-TKIs according to p53 status. Changes in p53 status affected primary sensitivity as well as acquired resistance to EGFR-TKIs according to cell type. Firstly, p53 silencing did not affect primary and acquired resistance to EGFR-TKIs in PC-9 cells, but it led to primary resistance to EGFR-TKIs through AXL induction in HCC827 cells. Secondly, p53 silencing in H1975 cells enhanced the sensitivity to osimertinib through the emergence of mesenchymal-to-epithelial transition, and the emergence of acquired resistance to osimertinib in p53 knockout cells was much slower than in H1975 cells. Furthermore, two cell lines (H1975 and H1975/p53^KO) demonstrated the different mechanisms of acquired resistance to osimertinib. Lastly, the introduction of mutant p53-R273H induced the epithelial-to-mesenchymal transition and exerted resistance to EGFR-TKIs in cells with activating EGFR mutations. These findings indicate that p53 mutations can be associated with primary or acquired resistance to EGFR-TKIs. Thus, the status or mutations of p53 may be considered as routes to improving the therapeutic effects of EGFR-TKIs in NSCLC.

Cdc25B is transcriptionally inhibited by IER5 through the NF-YB transcription factor in irradiation-treated HeLa cells

Cervical cancer (CC) is a type of pelvic malignant tumor that severely threatens women's health. Current evidence suggests that IER5, as a potential radiosensitizer, promotes irradiation-induced apoptosis in CC tissues in patients undergoing chemoradiotherapy. IER5 has been shown to be involved in the G₂/M-phase transition. In the present study, we used Cdc25B as the breakthrough point to explore the underlying mechanism of IER5 in the cell cycle regulation of radiation-damaged HeLa cells. IER5 was evidently upregulated after irradiation, but Cdc25B was significantly downregulated. In monoclonal IER5-silenced HeLa cells, irradiation-induced downregulation of Cdc25B was attenuated. The effect of irradiation on Cdc25B promoter activity was determined by dual-luciferase reporter assays. The response elements on the Cdc25B promoter related to irradiation were predicted by JASPAR. These conserved sequences were mutated individually or in combination by splicing-by-overlap extension PCR, and their function was confirmed by dual-luciferase reporter assays. The enrichment efficiency of transcription factors after irradiation was determined by chromatin immunoprecipitation (ChIP) assay. Both Sp1/Sp3 and NF-YB binding sites were involved in irradiation-mediated regulation of Cdc25B. IER5 was involved in irradiation-mediated regulation of Cdc25B through the NF-YB binding site. Furthermore, ChIP assays showed that IER5 bound to the Cdc25B promoter, and the binding of IER5 to the Cdc25B promoter region in irradiation-induced HeLa cells induced the release of the coactivator p300 through interaction with NF-YB. Taken together, these findings indicate that IER5 is the transcriptional repressor that accelerates the downregulation of Cdc25B expression after irradiation.

P300 Participates in Ionizing Radiation-Mediated Activation of Cathepsin L by Mutant p53

Our previous studies have shown that cathepsin L (CTSL) is involved in the ability of tumors to resist ionizing radiation (IR), but the specific mechanisms responsible for this remain unknown. We report here that mutant p53 (mut-p53) is involved in IR-induced transcription of CTSL. We found that irradiation caused activation of CTSL in mut-p53 cell lines, whereas there was almost no activation in p53 wild-type cell lines. Additionally, luciferase reporter gene assay results demonstrated that IR induced the p53 binding region on the CTSL promoter. We further demonstrated that the expression of p300 and early growth response factor-1 (Egr-1) was upregulated in mut-p53 cell lines after IR treatment. Accordingly, the expression of Ac-H3, Ac-H4, AcH3K9 was upregulated after IR treatment in mut-p53 cell lines, whereas histone deacetylase (HDAC) 4 and HDAC6 were reciprocally decreased. Moreover, knockdown of either Egr-1 or p300 abolished the binding of mut-p53 to the promoter of CTSL. Chromatin immunoprecipitation assay results showed that the IR-activated transcription of CTSL was dependent on p300. To further delineate the clinical relevance of interactions between Egr-1/p300, mut-p53, and CTSL, we accessed primary tumor samples to evaluate the relationships between mut-p53, CTSL, and Egr-1/p300 ex vivo. The results support the notion that mut-p53 is correlated with CTSL transcription involving the Egr-1/p300 pathway. Taken together, the results of our study revealed that p300 is an important target in the process of IR-induced transcription of CTSL, which confirms that CTSL participates in mut-p53 gain-of-function. SIGNIFICANCE STATEMENT: Transcriptional activation of cathepsin L by ionizing radiation required the involvement of mutated p53 and Egr-1/p300. Interference with Egr-1 or p300 could inhibit the expression of cathepsin L induced by ionizing radiation. The transcriptional activation of cathepsin L by p300 may be mediated by p53 binding sites on the cathepsin L promoter.

The pan-cancer landscape of crosstalk between epithelial-mesenchymal transition and immune evasion relevant to prognosis and immunotherapy response

An emerging body of evidence has recently recognized the coexistence of epithelial-mesenchymal transition (EMT) and immune response. However, a systems-level view and survey of the interplay between EMT and immune escape program, and their impact on tumor behavior and clinical outcome across various types of cancer is lacking. Here, we performed comprehensive multi-omics analyses to characterize the landscape of crosstalk between EMT and immune evasion and their clinical relevance across 17 types of solid cancer. Our study showed the presence of complex and dynamic immunomodulatory crosstalk between EMT and immune evasion shared by pan-cancer, and the crosstalk was significantly associated with cancer prognosis and immunotherapy response. Integrative quantitative analyses of genomics and immunogenomics revealed that cellular composition of immune infiltrates, non-synonymous mutation burden, chromosomal instability and oncogenic gene alterations are associated with the balance between EMT and immune evasion. Finally, we proposed a scoring model termed EMT-CYT Index (ECI) to quantify the EMT-immunity axis, which was a superior predictor of prognosis and immunotherapy response across different malignancies. By providing a systematic overview of crosstalk between EMT and immune evasion, our study highlights the potential of pan-cancer EMT-immunity crosstalk as a paradigm for dissecting molecular mechanisms underlying cancer progression and guiding more effective and generalized immunotherapy strategies.

A Correlation Study of Prognostic Risk Prediction for Colorectal Cancer Based on Autophagy Signature Genes

Autophagy plays a complex role in tumors, sometimes promoting cancer cell survival and sometimes inducing apoptosis, and its role in the colorectal tumor microenvironment is controversial. The purpose of this study was to investigate the prognostic value of autophagy-related genes (ARGs) in colorectal cancer. We identified 37 differentially expressed autophagy-related genes by collecting TCGA colorectal tumor transcriptome data. A single-factor COX regression equation was used to identify 11 key prognostic genes, and a prognostic risk prediction model was constructed based on multifactor COX analysis. We classified patients into high and low risk groups according to prognostic risk parameters (p <0.001) and determined the prognostic value they possessed by survival analysis and the receiver operating characteristic (ROC) curve in the training and test sets of internal tests. In a multifactorial independent prognostic analysis, this risk value could be used as an independent prognostic indicator (HR=1.167, 95% CI=1.078-1.264, P<0.001) and was a robust predictor without any staging interference. To make it more applicable to clinical procedures, we constructed nomogram based on risk parameters and parameters of key clinical characteristics. The area under ROC curve for 3-year and 5-year survival rates were 0.735 and 0.718, respectively. These will better enable us to monitor patient prognosis, thus improve patient outcomes.

PlatyphyllenoneExerts Anti-Metastatic Effects on Human Oral Cancer Cells by Modulating Cathepsin L Expression, MAPK Pathway and Epithelial-Mesenchymal Transition

Advanced-stage oral cancers with lymph node metastasis are associated with poor prognosis and a high mortality rate. Although recent advancement in cancer treatment has effectively improved the oral cancer prognosis, the majority of therapeutic interventions are highly expensive and are associated with severe sideeffects. In the present study, we studied the efficacy of a diarylheptanoid derivative, platyphyllenone, in modulating the metastatic potential of human oral cancer cells. Specifically, we treated the human oral cancer cells (FaDu, Ca9-22, and HSC3) with different concentrations of platyphyllenone and measured the cell proliferation, migration, and invasion. The study findings revealed that platyphyllenonesignificantly inhibited the motility, migration, and invasion of human oral cancer cells. Mechanistically, platyphyllenone reduced p38 phosphorylation, decreased β-catenin and Slug, increased E-cadherin expression, and reduced cathepsin L expression, which collectively led to a reduction in cancer cell migration and invasion. Taken together, our study indicates that platyphyllenone exerts significant anti-metastatic effects on oral cancer cells by modulating cathepsin L expression, the MAPK signaling pathway, and the epithelial-mesenchymal transition process.

The Short Non-Coding RNA 1251-5p Regulates Stemness Transformation and Inhibits Aggression of Lung Malignant Tumor Cells

Our study investigated the effect of short-chain non-coding RNA 1251-5p on the movement and permeation of pulmonary carcinoma stem cells. LCSC in pulmonary carcinoma cells was determined and isolated by flow cytometry. After cell transfection, qRT-PCR and immunoblotting measured the level of MiR-1251-5p, MiR-650, SLC34A2, Oct4 and CD133. Spherometric mensuration was used to assess sphericity formation situation. Transwell analyzed the movement and permeation of cells, detected the relationship among MiR-1251-5p, MiR-650 and SLC34A2 by fluorescein enzyme report gene, and the results were verified by RIP and RNA pull-down detection methods. Knock-down of MiR-1251-5p can enhance the stem cell-like characteristics of LCC, promote cell migration and invasion, upregulate the level of MiR-650, Oct4 and CD133, and downregulate the level of SLC34A2, while MiR-650 inhibitor can restore the effect of the knock-down on the hyperplasia, movement and permeation of LCSC cells. Si-Mir-1251-5p promoted stem cell like characteristics of pulmonary carcinoma cell lineage H1299 and downregulated the expression of Oct4 and CD133, and upregulated the level of SLC34A2. SLC34A2 expression was negatively correlated with MiR-650 expression and positively correlated with MiR-1251-5p in LCSC cellular tissues. MiR-1251-5p regulates LCC stem cell-like state, and inhibits the movement and permeation of pulmonary carcinoma cells via MiR-650/SLC34A2 axis.

The Role of the Transcription Factor EGR1 in Cancer

Early growth response factor 1 (EGR1) is a transcription factor that is mainly involved in the processes of tissue injury, immune responses, and fibrosis. Recent studies have shown that EGR1 is closely related to the initiation and progression of cancer and may participate in tumor cell proliferation, invasion, and metastasis and in tumor angiogenesis. Nonetheless, the specific mechanism whereby EGR1 modulates these processes remains to be elucidated. This review article summarizes possible mechanisms of action of EGR1 in tumorigenesis and tumor progression and may serve as a reference for clinical efficacy predictions and for the discovery of new therapeutic targets.

The Deubiquitinating Enzyme UCHL1 Induces Resistance to Doxorubicin in HER2+ Breast Cancer by Promoting Free Fatty Acid Synthesis

Ubiquitin C-terminal hydrolase L1 (UCHL1), which is a deubiquitinating enzyme, is known to play a role in chemoresistance in cancers. However, its potential roles and mechanisms in the chemoresistance of breast cancer (BC) remain unclear. In this study, we examined its expression in patients with BC and employed Kaplan-Meier analysis and the log-rank test for survival analyses. It was found that up-regulated UCHL1 expression was positively associated with both chemoresistance and poor prognosis, especially in patients with HER2+ BC. Moreover, UCHL1 expression was elevated in HER2+ BC cells (SK-BR-3 and BT474). Similarly, doxorubicin (DOX)-resistant BC cells (MCF-7/DOX) had higher UCHL1 levels than MCF-7 cells. CCK-8 assay showed that BC cells with higher UCHL1 levels were more resistant to DOX. Furthermore, by inhibiting UCHL1 in BC cells with elevated UCHL1 expression, we demonstrated that UCHL1 promoted DOX-resistance in BC. Mechanistically, UCHL1 probably promoted DOX-resistance of BC by up-regulating free fatty acid (FFA) synthesis, as exhibited by reduced FFA synthase expression and resurrected DOX-sensitivity upon UCHL1 inhibition. Overall, UCHL1 up-regulation is associated with DOX-resistance and poor prognosis in patients with HER2+ BC. UCHL1 induces DOX-resistance by up-regulating FFA synthesis in HER2+ BC cells. Thus, UCHL1 might be a potential clinical target for overcoming DOX resistance in patients with HER2+ BC.

The p53/RMRP/miR122 signaling loop promotes epithelial-mesenchymal transition during the development of silica-induced lung fibrosis by activating the notch pathway

BACKGROUND

Understanding the roles of long noncoding RNAs (lncRNAs) in EMT would help with establishing novel avenues for further uncovering the mechanisms of lung fibrosis and identifying preventative and therapeutic targets. This study aimed to identify silica-induced specific lncRNAs and investigate the feedback loop regulation among their upstream and downstream genes.

METHODS AND MATERIALS

A microarray assay, quantitative real-time polymerase chain reaction and Western blot analysis dual-luciferase reporter gene activity and chromatin immunoprecipitation assays were used. Moreover, a silica-induced lung fibrosis mouse model was used to verify the roles of the lncRNAs.

RESULTS

Following silica exposure, both RNA component of mitochondrial RNA processing endoribonuclease (RMRP) and p53 were significantly upregulated during the EMT. The upregulation of p53 upon silica exposure activated RMRP expression, which promoted the EMT. When RMRP is overexpressed, additional RMRP acts as a sponge to bind to miR122, thus decreasing miR122 levels. Using microarrays, miR122 was identified as a potential upstream regulator of p53. This relationship was also verified using the dual-luciferase reporter gene. Hence, decreased miR122 levels result in an increase in p53 activity. More importantly, RMRP promotes the transcription of Notch 1, which, in turn, results in Notch pathway activation. We show that the p53/RMRP/miR122 pathway creates a positive feedback loop that promotes EMT progress by activating the Notch signaling pathway.

CONCLUSION

Our data indicated that p53/RMRP/miR122 feedback loop might contribute to the EMT development by activating Notch pathway, which provides new sight into understanding of the complex network regulating silica-induced lung fibrosis.

Making Connections: p53 and the Cathepsin Proteases as Co-Regulators of Cancer and Apoptosis

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the p53 and cathepsin proteins. While it has been demonstrated that the p53 protein can directly induce the leakage of cathepsin proteases from the lysosome, directly triggering cell death, little is known about what factors set the threshold at which the lysosome can become permeabilized. It appears that the expression levels of cathepsin proteases may be central to this process, with some of them being transcriptionally regulated by p53. The consequences of such a mechanism have serious implications for lysosomal-mediated apoptosis and have significant input into the design of therapeutics and their strategic use. In this review, we highlight the importance of extending such findings to other cathepsin family members and the need to assess the roles of p53 isoforms and mutants in furthering this mechanism.

Abstract

While viewed as the “guardian of the genome”, the importance of the tumor suppressor p53 protein has increasingly gained ever more recognition in modulating additional modes of action related to cell death. Slowly but surely, its importance has evolved from a mutated genetic locus heavily implicated in a wide array of cancer types to modulating lysosomal-mediated cell death either directly or indirectly through the transcriptional regulation of the key signal transduction pathway intermediates involved in this. As an important step in determining the fate of cells in response to cytotoxicity or during stress response, lysosomal-mediated cell death has also become strongly interwoven with the key components that give the lysosome functionality in the form of the cathepsin proteases. While a number of articles have been published highlighting the independent input of p53 or cathepsins to cellular homeostasis and disease progression, one key area that warrants further focus is the regulatory relationship that p53 and its isoforms share with such proteases in regulating lysosomal-mediated cell death. Herein, we review recent developments that have shaped this relationship and highlight key areas that need further exploration to aid novel therapeutic design and intervention strategies.

Integrative p53, micro-RNA and Cathepsin Protease Co-Regulatory Expression Networks in Cancer

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the transcriptional regulation of cathepsin protease genes by micro-RNAs that are connected to p53 activation. While it has been demonstrated that the p53 protein can directly regulate some cathepsin genes and the expression of their upstream regulatory micro-RNAs, very little is known about what input the p53 isoform proteins may have in regulating this relationship. Herein, we draw attention to this important regulatory aspect in the context of describing mechanisms that are being established for the micro-RNA regulation of cathepsin protease genes and their collective use in diagnostic or prognostic assays.

Abstract

As the direct regulatory role of p53 and some of its isoform proteins are becoming established in modulating gene expression in cancer research, another aspect of this mode of gene regulation that has captured significant interest over the years is the mechanistic interplay between p53 and micro-RNA transcriptional regulation. The input of this into modulating gene expression for some of the cathepsin family members has been viewed as carrying noticeable importance based on their biological effects during normal cellular homeostasis and cancer progression. While this area is still in its infancy in relation to general cathepsin gene regulation, we review the current p53-regulated micro-RNAs that are generating significant interest through their regulation of cathepsin proteases, thereby strengthening the link between activated p53 forms and cathepsin gene regulation. Additionally, we extend our understanding of this developing relationship to how such micro-RNAs are being utilized as diagnostic or prognostic tools and highlight their future uses in conjunction with cathepsin gene expression as potential biomarkers within a clinical setting.

Molecular crosstalk between cancer and neurodegenerative diseases

The progression of cancers and neurodegenerative disorders is largely defined by a set of molecular determinants that are either complementarily deregulated, or share remarkably overlapping functional pathways. A large number of such molecules have been demonstrated to be involved in the progression of both diseases. In this review, we particularly discuss our current knowledge on p53, cyclin D, cyclin E, cyclin F, Pin1 and protein phosphatase 2A, and their implications in the shared or distinct pathways that lead to cancers or neurodegenerative diseases. In addition, we focus on the inter-dependent regulation of brain cancers and neurodegeneration, mediated by intercellular communication between tumor and neuronal cells in the brain through the extracellular microenvironment. Finally, we shed light on the therapeutic perspectives for the treatment of both cancer and neurodegenerative disorders.

The deubiquitinating enzyme UCHL1 promotes resistance to pemetrexed in non-small cell lung cancer by upregulating thymidylate synthase

Rationale: Resistance to pemetrexed (PEM)-based chemotherapy is a major cause of progression in non-small cell lung cancer (NSCLC) patients. The deubiquitinating enzyme UCHL1 was recently found to play important roles in chemoresistance and tumor progression. However, the potential roles and mechanisms of UCHL1 in PEM resistance remain unclear.

Methods: Bioinformatics analyses and immunohistochemistry were used to evaluate UCHL1 expression in NSCLC specimens. Kaplan-Meier analysis with the log-rank test was used for survival analyses. We established PEM-resistant NSCLC cell lines by exposing them to step-wise increases in PEM concentrations, and in vitro and in vivo assays were used to explore the roles and mechanisms of UCHL1 in PEM resistance using the NSCLC cells.

Results: In chemoresistant tumors from NSCLC patients, UCHL1 was highly expressed and elevated UCHL1 expression was strongly associated with poor outcomes. Furthermore, UCHL1 expression was significantly upregulated in PEM-resistant NSCLC cells, while genetic silencing or inhibiting UCHL1 suppressed resistance to PEM and other drugs in NSCLC cells. Mechanistically, UCHL1 promoted PEM resistance in NSCLC by upregulating the expression of thymidylate synthase (TS), based on reduced TS expression after UCHL1 inhibition and re-emergence of PEM resistance upon TS restoration. Furthermore, UCHL1 upregulated TS expression, which mitigated PEM-induced DNA damage and cell cycle arrest in NSCLC cells, and also conferred resistance to PEM and other drugs.

Conclusions: It appears that UCHL1 promotes PEM resistance by upregulating TS in NSCLC cells, which mitigated DNA damage and cell cycle arrest. Thus, UCHL1 may be a therapeutic target for overcoming PEM resistance in NSCLC patients.

USP5 Promotes Metastasis in Non-Small Cell Lung Cancer by Inducing Epithelial-Mesenchymal Transition via Wnt/β-Catenin Pathway

Ubiquitin-specific protease 5 (USP5) is a deubiquitinating enzyme that functions as an oncoprotein in a variety of human cancers. However, the expression and role of USP5 in the metastasis of non-small cell lung cancer (NSCLC) have not been addressed. In this study, we examined the expression and prognostic significance of USP5 in NSCLC. The results revealed that USP5 was overexpressed and correlated with metastasis and overall survival in NSCLC tissues. A further in vitro study revealed that the levels of USP5 protein in NSCLC cells were associated with epithelial–mesenchymal transition (EMT) markers. Furthermore, USP5 overexpression significantly enhanced, whereas USP5 silencing significantly decreased the expression of EMT proteins and migration and invasion of NSCLC cells. In addition, the results from western blotting demonstrated that USP5 regulated EMT via the Wnt/β-catenin signaling pathway. Further immunohistochemical analysis revealed that USP5 was significantly associated with the expression of β-catenin and EMT markers in NSCLC tissues. Overall, USP5 upregulation is associated with tumor metastasis and poor prognosis in patients with NSCLC. USP5 promotes EMT and the invasion and migration of NSCLC cells. Therefore, USP5 may serve as a novel prognostic biomarker and provide a potential target for the treatment of metastasis in NSCLC.

The role of proteases in epithelial-to-mesenchymal cell transitions in cancer

Changing the characteristics of cells from epithelial states to mesenchymal properties is a key process involved in developmental and physiological processes as well as in many diseases with cancer as the most prominent example. Nowadays, a great deal of work and literature concerns the understanding of the process of epithelial-to-mesenchymal transition (EMT) in terms of its molecular regulation and its implications for cancer. Similar statements can certainly be made regarding the investigation of the more than 500 proteases typically encoded by a mammalian genome. Specifically, the impact of proteases on tumor biology has been a long-standing topic of interest. However, although EMT actively regulates expression of many proteases and proteolytic enzymes are clearly involved in survival, division, differentiation, and movements of cells, information on the diverse roles of proteases in EMT has been rarely compiled. Here we aim to conceptually connect the scientific areas of "EMT" and "protease" research by describing how several important classes of proteolytic enzymes are regulated by EMT and how they are involved in initiation and execution of the EMT program. To do so, we briefly introduce the evolving key features of EMT and its regulation followed by discussion of protease involvement in this process.

Curcumin Inhibits the Migration and Invasion of Non-Small-Cell Lung Cancer Cells Through Radiation-Induced Suppression of Epithelial-Mesenchymal Transition and Soluble E-Cadherin Expression

Radiotherapy has been reported to cause cancer metastasis. Thus, a new strategy for radiotherapy must be developed to avoid this side effect. A549 cells were exposed to radiation to induce an epithelial-mesenchymal transition (EMT) cell model. Real-time PCR and western blotting were used to detect mRNA and protein expression levels, and Transwell invasion and wound healing assays were used to detect cell migration and invasion. ELISA was used to detect soluble E-cadherin (sE-cad) secretion. siRNA was used to silence MMP9 expression. The results show that A549R cells exhibited an EMT phenotype with increased E-cadherin, N-cadherin, Snail, Slug, vimentin and Twist expression and decreased pan-keratin expression. sE-cad levels were increased in A549R cells and in the serum of NSCLC patients with distant metastasis. Exogenous sE-cad treatment and sE-cad overexpression promoted A549R and A549 cell migration and invasion. In contrast, blocking sE-cad attenuated A549 cell migration and invasion. Curcumin inhibited sE-cad expression and reversed EMT induced by radiation. Furthermore, curcumin suppressed sE-cad-enhanced A549 and A549R cell migration and invasion. Curcumin inhibited MMP9 expression, and silencing MMP9 suppressed sE-cad expression. Taken together, we found a nonclassic EMT phenomenon induced by radiation. Curcumin inhibits NSCLC migration and invasion by suppressing radiation-induced EMT and sE-cad expression by decreasing MMP9 expression.

K-3-Rh Protects Against Cerebral Ischemia/Reperfusion Injury by Anti-Apoptotic Effect Through PI3K-Akt Signaling Pathway in Rat

BACKGROUND/AIMS

Ischemic stroke is the main cause of nerve damage and brain dysfunction, accompanied by strong brain cell apoptosis. This study aimed to investigate the effect of kaempferol-3-O-rhamnoside (K-3-rh) on cerebral ischemia-reperfusion (I/R) injury.

METHODS AND MATERIALS

A rat model of cerebral I/R injury was established. The effects of K-3-rh on cerebral infarction size, brain water content and neurological deficits in rats were evaluated. Apoptosis of ischemic brain cells after mouse I/R was observed by TUNEL staining and flow cytometry. Western blot and qRT-PCR were used to detect the effect of K-3-rh on the expression of apoptosis-related proteins.

RESULTS

K-3-rh can improve the neurological deficit score, reduce the infarct volume and brain water content, and inhibit cell apoptosis. In addition, K-3-rh significantly downregulated the expression of Bax and p53 and upregulated the expression of Bcl-2, and the phosphorylation level of Akt. Blockade of PI3K activity by the PI3K inhibitor wortmannin not only reversed the effects of K-3-rh on infarct volume and brain water content but also reversed the expression level of p-Akt.

CONCLUSION

K-3-rh had obvious neuroprotective effects on brain I/R injury and neuronal apoptosis, and its mechanism may be related to activation of PI3K/Akt signaling pathway.

Friend or foe, the role of EGR-1 in cancer

Early growth response-1 (EGR-1), also termed NEFI-A and Krox-24, as a multi-domain protein is implicated in several vital physiological processes, including development, metabolism, cell growth and proliferation. Previous studies have implied that EGR-1 was producing in response to the tissue injury, immune response and fibrosis. Meanwhile, emerging studies stressed the pronounced correlation of EGR-1 and human cancers. Nevertheless, the intricate mechanisms of cancer-reduce EGR-1 alteration still poorly characterized. In the review, we evaluated the effects of EGR-1 in tumor cell proliferation, apoptosis, migration, invasion and tumor microenvironment, and then, we dwell on the intricate signaling pathways that EGR-1 involved in. The aberrantly expressed of EGR-1 in cancers are expected to provide a new cancer therapy strategy or a new marker for assessing treatment efficacy.

Deficiency of 15-LOX-1 Induces Radioresistance through Downregulation of MacroH2A2 in Colorectal Cancer

Despite the importance of radiation therapy, there are few radiation-related markers available for use in clinical practice. A larger catalog of such biomarkers is required to help clinicians decide when radiotherapy should be replaced with a patient-specific treatment. Arachidonate 15-lipoxygenase (15-LOX-1) enzyme is involved in polyunsaturated fatty acid metabolism. When colorectal cancer (CRC) cells were exposed to radiation, 15-LOX-1 was upregulated. To verify whether 15-LOX-1 protects against or induces DNA damage, we irradiated sh15-LOX-1 stable cells. We found that low 15-LOX-1 is correlated with radioresistance in CRC cells. These data suggest that the presence of 15-LOX-1 can be used as a marker for radiation-induced DNA damage. Consistent with this observation, gene-set-enrichment analysis based on microarray experiments showed that UV_RESPONSE was decreased in sh15-LOX-1 cells compared to shCon cells. Moreover, we discovered that the expression of the histone H2A variant macroH2A2 was sevenfold lower in sh15-LOX-1 cells. Overall, our findings present mechanistic evidence that macroH2A2 is transcriptionally regulated by 15-LOX-1 and suppresses the DNA damage response in irradiated cells by delaying H2AX activation.

Sustained Egr-1 Response via p38 MAP Kinase Signaling Modulates Early Immune Responses of Dendritic Cells Parasitized by Toxoplasma gondii

As a response to a diverse array of external stimuli, early growth response protein 1 (Egr-1) plays important roles in the transcriptional regulation of inflammation and the cellular immune response. However, a number of intracellular pathogens colonize immune cells and the implication of Egr-1 in the host-pathogen interplay has remained elusive. Here, we have characterized the Egr-1 responses of primary murine and human dendritic cells (DCs) upon challenge with the obligate intracellular parasite Toxoplasma gondii. We report that live intracellular parasites induce a sustained high expression of Egr-1 in DCs, different from the immediate-early Egr-1 response to parasite lysates, inactivated parasites or LPS. Moreover, a distinct nuclear localization of elevated amounts of Egr-1 protein was detected in infected DCs, but not in by-stander DCs. The ERK1/2 MAPK signaling pathway mediated the canonical immediate-early Egr-1 response to soluble antigens in a MyD88/TLR-dependent fashion. In contrast, a non-canonical extended Egr-1 response that relied primarily on p38 MAPK signaling was induced by intracellular parasites and was exhibited similarly by MyD88-deficient and wildtype DCs. The extended phase Egr-1 response was dramatically reduced upon challenge of DCs with T. gondii parasites deficient in GRA24, a secreted p38-interacting protein. Further, Egr-1-silenced primary DCs maintained their migratory responses upon T. gondii challenge. Importantly, Egr-1 silencing led to elevated expression of co-stimulatory molecules (CD40, CD80) in Toxoplasma-infected DCs and in LPS-challenged immature DCs, indicating that Egr-1 responses suppressed maturation of DCs. Moreover, the IL-12 and IL-2 responses of Toxoplasma-challenged DCs were modulated in a GRA24-dependent fashion. Jointly, the data show that the Egr-1 responses of DCs to microbial external stimuli and intracellular stimuli can be selectively mediated by ERK1/2 or p38 MAPK signaling, and that Egr-1 can act as an intrinsic negative modulator of maturation in primary DCs.

Cathepsin L-mediated resistance of paclitaxel and cisplatin is mediated by distinct regulatory mechanisms

BACKGROUND

Cathepsin L (CTSL) is a cysteine protease known to have important roles in regulating cancer cellular resistance to chemotherapy. However mechanism underlying which regulates CTSL-mediated drug resistance remain largely unknown.

METHODS

We used NSCLC cell lines: A549, A549/TAX (paclitaxel-resistant), A549/DDP (cisplatin-resistant), H460 and PC9 cells, to evaluate CTSL and drug resistance changes. Tumor specimens from 53 patients with NSCLC and Xenograft models was also utilized to explore the regulatory relationship of CTSL, TGF-β, Egr-1 and CREB.

RESULTS

TGF-β and smad3 were overexpressed only in A549/TAX cells, silencing TGF-β or smad3 in A549/TAX cells decreased the expression of CTSL and enhanced their sensitivity to paclitaxel. Smad3 binds to the Smad-binding-element(SBE) of the CTSL promoter, resulting in increased activity of the CTSL promoter and subsequent CTSL. Egr-1 and CREB were overexpressed only in A549/DDP cells, and silencing Egr-1 or CREB reduced the expression of CTSL and increased cisplatin cytotoxicity. CREB could affect the activity of the CTSL promoter by binding to it. And the potential regulatory factors of CTSL were consistent in vivo and in human lung cancer. These different regulatory mechanisms of CTSL-mediated drug resistance exist in two other NSCLC cell lines.

CONCLUSION

CTSL-mediated drug resistance to paclitaxel and cisplatin may be modulated by different mechanisms. The results of our study identified different mechanisms regulating CTSL-mediated drug resistance and identified smad3 as a novel regulator of CTSL.