The RNA-binding protein PCBP2 facilitates gastric carcinoma growth by targeting miR-34a

Unveiling poly(rC)-binding protein 2 as the target protein for curcusone C against prostate cancer: mechanism validation through click chemistry-activity based proteomics profiling approach

BACKGROUND

Prostate cancer is a disease that seriously troubles men. However, there are some inevitable limitations in interventional therapy for prostate cancer patients at present, most of which are caused by low selectivity and high toxic side effects due to unclear drug targets. In this study, we identified the target protein of Curcusone C with anti-prostate cancer potential activity and verified its target and mechanism of action.

METHODS

Click chemistry-activity based proteomics profiling (CC-ABPP) method was used to find target protein of Curcusone C against prostate cancer. Competitive CC-ABPP, drug affinity responsive target stability (DARTS) and surface plasmon resonance (SPR) methods were used to verifying the target protein. Moreover, potential mechanism was validated by western blot in vitro and by hematoxylin-eosin (HE) staining, detection of apoptosis in tumor tissue (TUNEL), and immunohistochemical (IHC) in vivo.

RESULTS

We found that poly(rC)-binding protein 2 (PCBP2) was the target protein of Curcusone C. In addition, Curcusone C might disrupt the Bax/Bcl-2 balance in PC-3 cells by inhibiting the expression of the target protein PCBP2, thereby inducing mitochondrial damage and activation of the mitochondrial apoptosis pathway, and ultimately inducing apoptosis of prostate cancer cells.

CONCLUSIONS

Curcusone C is a potential compound with anti-prostate cancer activity, and this effect occurs by targeting the PCBP2 protein, which in turn may affect the TGF/Smad signaling pathway and Bax/Bcl-2 balance. Our results laid a material and theoretical foundation for Curcusone C, to be widely used in anti-prostate cancer.

MiR-5195-3p targets the PCBP2/PI3K/AKT pathway to inhibit melanoma cell proliferation and migration

Although miR-5195-3p has been acknowledged for its tumor suppressor role in diverse cancer categories, its precise functions and mechanisms concerning melanoma have not been comprehensively elucidated. In this study, we employed quantitative reverse transcription PCR, Western blot analysis, and immunohistochemistry staining to investigate the expression patterns of miR-5195-3p and poly (rC) binding protein 2 (PCBP2) in melanoma tissues compared to adjacent tissues. Our findings revealed downregulation of miR-5195-3p and upregulation of PCBP2 in melanoma tissues. Through the implementation of a luciferase reporter assay, we successfully identified PCBP2 as a newly discovered target of miR-5195-3p in melanoma cells. Enforced expression of miR-5195-3p via mimics inhibited cell proliferation and migration in A375 and A2058 cells, as demonstrated by CCK-8 and transwell migration assays. In melanoma cells, reintroduction of PCBP2 partially reversed the inhibitory effects of miR-5195-3p overexpression. Treatment with LY294002, an inhibitor of the PI3K/AKT signaling pathway, also reversed the effects of PCBP2 in melanoma cells. Furthermore, our results suggest that miR-5195-3p inhibits the activation of the PI3K/AKT signaling pathway in melanoma by inhibiting PCBP2. In conclusion, our research has identified the miR-5195-3p targeting of the PCBP2-mediated PI3K/AKT signaling pathway as a potential therapeutic target for melanoma treatment.

Research progress on RNA−binding proteins in breast cancer

Breast cancer is the most common malignancy in women and has a high incidence rate and mortality. Abnormal regulation of gene expression plays an important role in breast cancer occurrence and development. RNA-binding proteins (RBPs) are one kind of the key regulators for gene expression. By interacting with RNA, RBPs are widely involved in RNA cutting, transport, editing, intracellular localization, and translation regulation. RBPs are important during breast cancer occurrence and progression by engaging in many aspects, like proliferation, migration, invasion, and stemness. Therefore, comprehensively understanding the role of RBPs in breast cancer progression can facilitate early diagnosis, timely treatment, and long-term survival and quality of life of breast cancer patients.

RNA-Binding Protein COL14A1, TNS1, NUSAP1 and YWHAE Are Valid Biomarkers to Predict Peritoneal Metastasis in Gastric Cancer

Gastric cancer (GC) is the third leading cause of tumor related mortality worldwide. Peritoneal metastasis (PM) occurs in more than half of advanced GC patients, leading to poor prognosis. Therefore, the GSE62254 cohort was used to construct a signature consisting of four RNA-binding proteins (RBP) to predict the possibility of PM in GC patients. Then, ROC curves were plotted followed by calculation of AUCs, showing that the signature had a similar predictive accuracy compared with the TNM staging system. Importantly, the capability of prediction was enhanced by combining the classifier and TNM staging. In order to validate the expression of the four RBPs in GC tissues with and without PM, immunohistochemistry was further performed on samples from 108 patients. The differential expression of COL14A1, TNS1, NUSAP1 and YWHAE was in accordance with the emergence of PM. Afterwards, we produced Kaplan–Meier curves according to the signature and differential expression of the RBPs in patients. Finally, CCK-8 assays were performed to verify the effect on cell proliferation, finding that COL14A1 and TNS1 promoted cell proliferation, while NUSAP1 and YWHAE led to suppressed cell proliferation. In conclusion, the four-RBP-based signature, combined with TNM staging, has the potential to predict risk of PM in GC.

Role of miR-490-3p in blocking bladder cancer growth through targeting the RNA-binding protein PCBP2

MiR-490-3p is regarded as a tumor suppressor in many cancers, but whether miR-490-3p is involved in the development of bladder cancer remains unknown. BALB/c nude mice (male, 15-20 g) were used to investigate the role of MiR-490-3p in bladder cancer. The relationship between miR-490-3p and PCBP2 involved in bladder cancer regulation were determined. Cell viability, proliferation, and cell cycle were estimated by cell counting kit-8 (CCK-8) assay, 5-bromo-2'-deoxyuridine (BrdU) detection, and flow cytometry analysis, respectively. In animal experiments, lentivirus was transfected into bladder cancer cells to overexpress miR-490-3p, which were then injected into mice and the change of tumor volume was assessed. Principal findings: The expression of MiR-490-3p was decreased in bladder cancer cells. Overexpression of miR-490-3p inhibited bladder cancer cell viability and proliferation. Moreover, overexpression of miR-490-3p caused cell cycle arrest in bladder cancer cells. The inhibitory effect of miR-490-3p on bladder cancer cells growth could be counteracted by enhancing PCBP2 expression. In vivo, bladder cancer growth in mice was blocked by miR-490-3p upregulation. MiR-490-3p suppressed bladder cancer growth and bladder cancer cell proliferation by down-regulating PCBP2 expression.

Advances in poly(rC)-binding protein 2: Structure, molecular function, and roles in cancer

Poly(rC)-binding protein 2 (PCBP2) is an RNA-binding protein that is characterized by its ability to interact with poly(C) with high affinity in a sequence-specific manner. PCBP2 contains three K homology domains, which are consensus RNA-binding domains that play a role in recognizing and combining with RNA and DNA. The specific structure and localization of PCBP2 lay the foundation for its multiple roles in transcriptional, posttranscriptional, and translational processes, even in iron metabolism. Numerous studies have indicated that PCBP2 expression is increased in many cancer types. PCBP2 is considered as an oncogene that promotes tumorigenesis, development of cancer cells, and metastasis. Here, we summarized the current evidence regarding PCBP2 in the proliferation, migration, invasion of cancer cells, and drug resistance, aiming to clarify the molecular mechanisms of PCBP2 in cancer. Results from this review suggest that an in-depth study of PCBP2 in cancer may provide novel biomarkers for prognostic or therapeutic purposes.

The comprehensive landscape of miR-34a in cancer research

MicroRNA-34 (miR-34) plays central roles in human diseases, especially cancers. Inactivation of miR-34 is detected in cancer cell lines and tumor tissues versus normal controls, implying its potential tumor-suppressive effect. Clinically, miR-34 has been identified as promising prognostic indicators for various cancers. In fact, members of the miR-34 family, especially miR-34a, have been convincingly proved to affect almost the whole cancer progression process. Here, a total of 512 (miR-34a, 10/21), 85 (miR-34b, 10/16), and 114 (miR-34c, 10/14) putative targets of miR-34a/b/c are predicted by at least ten miRNA databases, respectively. These targets are further analyzed in gene ontology (GO), KEGG pathway, and the Reactome pathway dataset. The results suggest their involvement in the regulation of signal transduction, macromolecule metabolism, and protein modification. Also, the targets are implicated in critical signaling pathways, such as MAPK, Notch, Wnt, PI3K/AKT, p53, and Ras, as well as apoptosis, cell cycle, and EMT-related pathways. Moreover, the upstream regulators of miR-34a, mainly including transcription factors (TFs), lncRNAs, and DNA methylation, will be summarized. Meanwhile, the potential TF upstream of miR-34a/b/c will be predicted by PROMO, JASPAR, Animal TFDB 3.0, and GeneCard databases. Notably, miR-34a is an attractive target for certain cancers. In fact, miR-34a-based systemic delivery combined with chemotherapy or radiotherapy can more effectively control tumor progression. Collectively, this review will provide a panorama for miR-34a in cancer research.

PCBP2 Posttranscriptional Modifications Induce Breast Cancer Progression via Upregulation of UFD1 and NT5E

It is commonly accepted that cellular protein levels are primarily determined by mRNA levels. However, discordance between protein and mRNA expression has been implicated in many pathologic conditions including oncogenesis. The mechanisms involved in this discordance are complicated and far from understood. In this study, it was observed that the expression levels of poly(C) binding protein 2 (PCBP2) mRNA and protein were diametric in breast normal and cancer cell lines, paraffin-embedded and fresh tissue specimens, consistent with data from The Cancer Genome Atlas and the Clinical Proteomic Tumor Analysis Consortium. Moreover, PCBP2 protein expression was significantly associated with disease progression and poor outcome in patients with breast cancer. Depletion of PCBP2 protein inhibited cell proliferation, colony formation, migration, invasion, and in vivo tumor growth and metastasis. Forced expression of PCBP2 exhibited the opposite effect. Mechanistically, it was demonstrated that PCBP2 3' untranslated region (3'UTR) was subject to alternative splicing and polyadenylation (APA) in breast cancer tissues and cell lines. Non-full-length 3'UTR PCBP2 transcripts yielded more protein than the full-length 3'UTR transcripts and enhanced the oncogenic and metastatic capacities of human breast cancer cells. Furthermore, UFD1 and NT5E were identified as genes downstream of PCBP2. PCBP2 promoted oncogenicity of breast cancer cells via upregulation of the expression of UFD1 and NT5E by direct binding to their 3'UTR-B portions. IMPLICATIONS: Findings demonstrate that APA of PCBP2 3'UTR contributes to its increased expression with subsequent promotion of breast cancer progression by regulating UFD1 and NT5E. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/1/86/F1.large.jpg.

miR-9, miR-21, miR-27b, and miR-34a Expression in HPV16/58/52-Infected Cervical Cancer

The aim of this study was to observe the expression of miR-9, miR-21, miR-27b, and miR-34a related with E6/E7 in HPV16-, HPV52-, and HPV58-infected cervical cancer patients and explore their possible role in cervical cancer with HPV infection. The expression levels of 4 miRNAs were detected in cervical exfoliated cells using qRT-PCR. In the current study, miR-34a expression was significantly upregulated in HPV-positive cervical cancer compared with the HPV-negative healthy population and HPV-positive CIN, but just the expression of miR-34a in HPV16 cervical cancer was statistically significant, and the expression of HPV52 and HPV58 was not statistically significant. The expression of miR-21 increased in HPV-positive cervical cancer compared with HPV-positive CIN, but only HPV16-infected cervical cancer had statistical significance compared with HPV16-infected CIN. By observing the change trend of each subtype group, we can show that the expression of miR-9 in HPV16 CIN was opposite to the other subtypes, and it was upregulated, compared with HPV58 CIN, and significantly increased. The level change of miR-27b in HPV58 cervical cancer and HPV58 CIN was opposite to the other subtypes; unlike the expression of miR-27b which was upregulated in HPV16 and HPV52 infected, it was downregulated compared with Normal. We also found that the expression of miR-34a and miR-9 was contrary to other studies. These findings indicate that the upregulated miR-21 expression may be a biomarker to distinguish between CC and CIN. miR-34a in HPV infection, especially in HPV16 infection, might be related to the occurrence and development of cervical cancer. The infection of different subtypes may play different roles in disease by activating different mechanisms; miRNAs play a very complex role in tumorigenesis and development, and there may be multiple targets in which multiple mechanisms play a role.

LINC02535 co-functions with PCBP2 to regulate DNA damage repair in cervical cancer by stabilizing RRM1 mRNA

Cervical cancer (CC) is one of the commonest malignant cancers among women with high morbidity and mortality. Despite encouraging advances had been found in diagnostic and therapeutic strategies, effective therapeutic strategy and further exploration of the mechanism underlying in CC is still needed. We searched The Cancer Genome Atlas database and found that long noncoding RNA LINC02535 was highly expressed in CC. LINC02535 has not been studied in CC, and its molecular regulation mechanism remains unknown. Based on starBase database, LINC02535 could potentially bind poly (rC) binding protein 2 (PCBP2). In the present study, we discovered a significant increase of the LINC02535 and PCBP2 expression in CC tissues and cells as compared with the adjacent normal tissues and normal cervical epithelial cells. LINC02535 and PCBP2 can bind with each other and were colocated in cytoplasm. LINC02535 and PCBP2 promoted cell proliferation, migration, invasion, and suppressed apoptosis in CC. LINC02535 and PCBP2 facilitated the repair of DNA damage to promote CC progression. LINC02535 cooperated with PCBP2 to enhance the stability of RRM1 messenger RNA (mRNA). RRM1 promoted the repair of DNA damage and epithelial-to-mesenchymal transition (EMT) process in CC cells. LINC02535 regulated tumorigenesis in vivo. In conclusion, LINC02535 cooperated with PCBP2, regulated stability of RRM1 mRNA to promote cell proliferation and EMT process in CC cells by facilitating the repair of DNA damage, providing a potential biomarker for CC.

A Systemic Review on the Regulatory Roles of miR-34a in Gastrointestinal Cancer

MicroRNAs (miRNAs) are a class of endogenous non-coding single-stranded small-molecule RNAs that regulate gene expression by repressing target messenger RNA (mRNA) translation or degrading mRNA. miR-34a is one of the most important miRNAs participating in various physiological and pathological processes. miR-34a is abnormally expressed in a variety of tumors. The roles of miR-34a in gastrointestinal cancer (GIC) draw lots of attention. Numerous studies have demonstrated that dysregulated miR-34a is closely related to the proliferation, differentiation, migration, and invasion of tumor cells, as well as the diagnosis, prognosis, treatment, and chemo-resistance of tumors. Thus, we systematically reviewed the abnormal expression and regulatory roles of miR-34a in GICs including esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), hepatocellular carcinoma (HCC), pancreatic cancer (PC), and gallbladder cancer (GBC). It may provide a profile of versatile roles of miR-34a in GICs.

Systematic profiling of a novel prognostic alternative splicing signature in hepatocellular carcinoma

Alternative splicing (AS) is a pervasive and vital mechanism involved in the progression of cancer by expanding genomic encoding capacity and increasing protein complexity. However, the systematic analysis of AS in hepatocellular carcinoma (HCC) is lacking and urgently required. In the present study, genome‑wide AS events with corresponding clinical information were profiled in 290 patients with HCC from the Cancer Genome Atlas and SpliceSeq software. Functional enrichment analyses revealed the pivotal biological process of AS regulation. Univariate Cox regression analyses were performed, followed by stepwise forward multivariate analysis to develop the prognostic signatures. Spearman's correlation analyses were also used to construct potential regulatory network between the AS events and aberrant splicing factors. A total of 34,163 AS events were detected, among which 1,805 AS events from 1,314 parent genes were significantly associated with the overall survival (OS) of patients with HCC, and their parent genes serve crucial roles in HCC‑related oncogenic processes, including the p53 signaling pathway, AMPK signaling pathway and HIF‑1 signaling pathway. A prognostic AS signature was established that was found to be an independent prognostic factor for OS in stratified cohorts, harboring a noteworthy ability to distinguish between the distinct prognoses of patients with HCC (high‑risk vs. low‑risk, 827 vs. 3,125 days, P<2e‑16). Time‑dependent receiver‑-operator characteristic curves confirmed its robustness and clinical efficacy, with the area under the curves maintained >0.9 for short‑term and long‑term prognosis prediction. The splicing correlation network suggested a trend in the interactions between splicing factors and prognostic AS events, further revealing the underlying mechanism of AS in the oncogenesis of HCC. In conclusion, the present study provides a comprehensive portrait of global splicing alterations involved in the progression and HCC in addition to valuable prognostic factors for patients, which may represent as underappreciated hallmark and provide novel clues of therapeutic targets in HCC.

Cancer the'RBP'eutics-RNA-binding proteins as therapeutic targets for cancer

RNA-binding proteins (RBPs) play a critical role in the regulation of various RNA processes, including splicing, cleavage and polyadenylation, transport, translation and degradation of coding RNAs, non-coding RNAs and microRNAs. Recent studies indicate that RBPs not only play an instrumental role in normal cellular processes but have also emerged as major players in the development and spread of cancer. Herein, we review the current knowledge about RNA binding proteins and their role in tumorigenesis as well as the potential to target RBPs for cancer therapeutics.

hnRNP K plays a protective role in TNF-α-induced apoptosis in podocytes

Apoptosis of podocytes contributes to proteinuria in many chronic kidney diseases. The cytokine, tumor necrosis factor-α (TNF-α) is thought to be involved in podocyte apoptosis, but the underlying mechanism is not understood. In our study, we established a model of TNF-α-induced apoptosis by isolating primary podocytes from mice. After exposing cells to TNF-α, we determined the expression levels of heterogeneous nuclear ribonucleoprotein K (hnRNP K) and cellular FLICE-inhibitory protein (c-FLIP) and the phosphorylation levels of glycogen synthase kinase β (GSK3β) and extracellular signal-regulated kinase (ERK). We then knocked down or overexpressed the levels of hnRNP K and observed its effects on the expressions of c-FLIP, caspase-8, caspase-3, and the phosphorylation of GSK3β and ERK. In addition, we examined the percentage of cells undergoing apoptosis and studied cell cycle distribution. We found that TNF-α induced apoptosis in podocytes and that the expressions of hnRNP K and c-FLIP were significantly decreased, whereas the phosphorylations of GSK3β and ERK were significantly increased. Both gene knockdown and overexpression of hnRPN K resulted in varied expressions/phosphorylations of c-FLIP, GSK3β, and ERK. Moreover, decreased hnRPN K expression contributed to increased levels of caspase-8 and capase-3, as well as an increase in cell apoptosis and G0/G1 arrest. In conclusion, down-regulated expression of hnRNP K by TNF-α resulted in a decrease in the expression of c-FLIP as well as increases in phosphorylated GSK3β, ERK, caspase-8, and caspase-3, and then critically contributed to the podocyte apoptosis.

Poly(rC) binding protein 2 (PCBP2) promotes the viability of human gastric cancer cells by regulating CDK2

Survival rates for patients with gastric cancer, especially the advanced form, remain poor and the development of targeted treatments is hampered by a lack of efficient biological targets. Poly(rC) binding protein 2 (PCBP2) is an RNA-binding protein that contributes to mRNA stabilization, translational silencing and enhancement and it has been implicated as a promoter of gastric cancer growth. In the present study, we demonstrated that the expression level of PCBP2 was higher in human gastric cancer tissues compared to adjacent normal gastric tissues. A high level of PCBP2 was correlated with worse postoperative relapse-free survival and overall survival rates of gastric cancer patients. Small hairpin RNA-mediated depletion of PCBP2 dramatically decreased the viability of gastric cancer cells. Cyclin-dependent kinase 2 (CDK2) was positively regulated by PCBP2 via a direct 3' UTR binding pathway as determined using a ribonucleoprotein immunoprecipitation assay and a biotin pulldown assay. CDK2 mediated the promoting role of PCBP2. These results suggest that PCBP2 acts as an oncogene in human gastric cancer cells and that functionally depleting PCBP2 could be considered as a potential target for gastric cancer therapy.

Role of G3BP1 in glucocorticoid receptor-mediated microRNA-15b and microRNA-23a biogenesis in endothelial cells

MicroRNAs (miRNAs) are a family of non-coding RNAs that play crucial roles in regulating various normal cellular responses. Recent studies revealed that the canonical miRNA biogenesis pathway is subject to sophisticated regulation. Hormonal control of miRNA biogenesis by androgen and estrogen has been demonstrated, but the direct effects of the glucocorticoid receptor (GR) on miRNA biogenesis are unknown. This study revealed the role of GR in miRNA maturation. We showed that two GR agonists, dexamethasone and ginsenoside-Rg1 rapidly suppressed the expression of mature miR-15b, miR-23a, and miR-214 in human endothelial cells. RNA pulldown coupled with proteomic analysis identified GTPase-activating protein (SH3 domain) binding protein 1 (G3BP1) as one of the RNA-binding proteins mediating GR-regulated miRNA maturation. Activated GR induced phosphorylation of v-AKT Murine Thymoma Viral Oncogene Homologue (AKT) kinase, which in turn phosphorylated and promoted nuclear translocation of G3BP1. The nuclear G3BP1 bound to the G3BP1 consensus sequence located on primary miR-15b~16-2 and miR-23a~27a~24-2 to inhibit their maturation. The findings from this study have advanced our understanding of the non-genomic effects of GR in the vascular system.

Proteomic identification of potential biomarkers for cervical squamous cell carcinoma and human papillomavirus infection

It is known that high-risk human papillomavirus infection is the main etiological factor in cervical carcinogenesis. However, human papillomavirus screening is not sufficient for early diagnosis. In this study, we aimed to identify potential biomarkers common to cervical carcinoma and human papillomavirus infection by proteomics for human papillomavirus-based early diagnosis and prognosis. To this end, we collected 76 cases of fresh cervical tissues and 116 cases of paraffin-embedded tissue slices, diagnosed as cervical squamous cell carcinoma, cervical intraepithelial neoplasia II-III, or normal cervix from ethnic Uighur and Han women. Human papillomavirus infection by eight oncogenic human papillomavirus types was detected in tissue DNA samples using a quantitative polymerase chain reaction. The protein profile of cervical specimens from human papillomavirus 16-positive squamous cell carcinoma and human papillomavirus-negative normal controls was analyzed by proteomics and bioinformatics. The expression of candidate proteins was further determined by quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry. We identified 67 proteins that were differentially expressed in human papillomavirus 16-positive squamous cell carcinoma compared to normal cervix. The quantitative reverse transcriptase-polymerase chain reaction analysis verified the upregulation of ASAH1, PCBP2, DDX5, MCM5, TAGLN2, hnRNPA1, ENO1, TYPH, CYC, and MCM4 in squamous cell carcinoma compared to normal cervix ( p < 0.05). In addition, the transcription of PCBP2, MCM5, hnRNPA1, TYPH, and CYC was also significantly increased in cervical intraepithelial neoplasia II-III compared to normal cervix. Immunohistochemistry staining further confirmed the overexpression of PCBP2, hnRNPA1, ASAH1, and DDX5 in squamous cell carcinoma and cervical intraepithelial neoplasia II-III compared to normal controls ( p < 0.05). Our data suggest that the expression of ASAH1, PCBP2, DDX5, and hnRNPA1, and possibly MCM4, MCM5, CYC, ENO1, and TYPH, is upregulated during cervical carcinogenesis and potentially associated with human papillomavirus infection. Further validation studies of the profile will contribute to establishing auxiliary diagnostic markers for human papillomavirus-based cancer prognosis.

The apoptotic and genomic studies on A549 cell line induced by silver nitrate

Lung cancer is the leading cause of male cancer deaths worldwide. Metal-based anticancer drugs have evolved significantly during the past decades. Recently, silver ions have been investigated for their anticancer effects. We aimed to study the time-course cytotoxic effects of silver nitrate on A549 adenocarcinomic human alveolar basal epithelial cells to provide insights into the molecular-level understanding of growth suppression mechanism involved in apoptosis. The influences of silver nitrate were studied via MTT assay, flow cytometry, immunocytochemical, confocal and transmission electron microscopy, and microarray assays. Silver nitrate showed inhibitory effects against A549 cells in a dose- and time-dependent manner for 24, 48, and 72 h and induced apoptosis. The early and late apoptotic cells and depolarized mitochondrial membrane potential were determined by the half-maximal inhibitory concentration (IC₅₀) value of silver nitrate treated for 72 h. But cysteinyl aspartate proteinase-3 was not activated for 72 h. Furthermore, IC₅₀ value of silver nitrate also induced apoptosis according to immunocytochemical assays for 72 h. The downregulated CCNY, HNRNPL, ASF1B, PIAS4, HNRNPH1, EIF2C2, TAF15, FOXC1, LEP, and PCB2 genes administered with silver nitrate IC₅₀ were identified as apoptosis-leading genes. Silver nitrate may be a suitable therapeutic agent against lung cancer.

Upregulation of Mir-34a in AGS Gastric Cancer Cells by a PLGA-PEG-PLGA Chrysin Nano Formulation

BACKGROUND

Nano-therapy has the potential to revolutionize cancer therapy. Chrysin, a natural flavonoid, was recently recognized as having important biological roles in chemical defenses and nitrogen fixation, with anti-inflammatory and anti-oxidant effects but the poor water solubility of flavonoids limitstheir bioavailability and biomedical applications.

OBJECTIVE

Chrysin loaded PLGA-PEG-PLGA was assessed for improvement of solubility, drug tolerance and adverse effects and accumulation in a gastric cancer cell line (AGS).

MATERIALS AND METHODS

Chrysin loaded PLGA-PEG copolymers were prepared using the double emulsion method (W/O/W). The morphology and size distributions of the prepared PLGA-PEG nanospheres were investigated by 1H NMR, FT-IR and SEM. The in vitro cytotoxicity of pure and nano-chrysin was tested by MTT assay and miR-34a was measured by real-time PCR.

RESULTS

1H NMR, FT-IR and SEM confirmed the PLGA-PEG structure and chrysin loaded on nanoparticles. The MTT results for different concentrations of chrysin at different times for the treatment of AGS cell line showed IC50 values of 68.2, 56.2 and 42.3 μM and 58.2, 44.2, 36.8 μM after 24, 48, and 72 hours of treatment, respectively for chrysin itslef and chrysin-loaded nanoparticles. The results of real time PCR showed that expression of miR-34a was upregulated to a greater extent via nano chrysin rather than free chrysin.

CONCLUSIONS

Our study demonstrates chrysin loaded PLGA-PEG promises a natural and efficient system for anticancer drug delivery to fight gastric cancer.

E3 ubiquitin ligase isolated by differential display regulates cervical cancer growth in vitro and in vivo via microRNA-143

Cervical cancer is one of the most common gynecological cancers worldwide. Aberrant expression of E3 ubiquitin ligase isolated by differential display (EDD) has been detected in various types of tumor and has been demonstrated to have an important role in carcinogenesis, tumor growth and drug resistance. However, the role of EDD in cervical cancer and its underlying molecular mechanisms remains unknown. The present study aimed to investigate the role of EDD in the tumorigenicity of cervical cancer. EDD expression levels were measured using reverse transcription-quantitative polymerase chain reaction and western blotting in SiHa, HeLa, CaSki, c-41 and c-33A cervical cancer cell lines and cervical cancer tissue specimens. A functional study was performed using cell proliferation, colony formation, cell apoptosis assays in vitro and tumor growth assays in vivo with EDD either overexpressed or silenced. In the present study, EDD expression levels were significantly upregulated in cervical cancer cell lines and tissue samples. EDD knockdown significantly inhibited colony formation, cell proliferation and tumor growth and accelerated cell apoptosis in the cervical cancer cell lines and tissue samples. Furthermore, microRNA (miR)-143 expression levels were low in cervical cancer tissue samples and were negatively correlated with EDD expression. miR-143 silencing eliminated the effect of EDD on cell proliferation, colony formation and cell apoptosis in the cervical cancer cells, which suggested that miR-143 is critical for EDD-mediated regulation of cervical cancer cell growth. The results of the present study indicated that EDD may promote cervical cancer growth in vivo and in vitro by targeting miR-143. In conclusion, EDD may have an oncogenic role in cervical cancer and may serve as a potential therapeutic target for the treatment of patients with cervical cancer.

Identification of HSPA8 as a candidate biomarker for endometrial carcinoma by using iTRAQ-based proteomic analysis

Although there are advances in diagnostic, predictive, and therapeutic strategies, discovering protein biomarker for early detection is required for improving the survival rate of the patients with endometrial carcinoma. In this study, we identify proteins that are differentially expressed between the Stage I endometrial carcinoma and the normal pericarcinous tissues by using isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analysis. Totally, we screened 1,266 proteins. Among them, 103 proteins were significantly overexpressed, and 30 were significantly downexpressed in endometrial carcinoma. Using the bioinformatics analysis, we identified a list of proteins that might be closely associated with endometrial carcinoma, including CCT7, HSPA8, PCBP2, LONP1, PFN1, and EEF2. We validated the gene overexpression of these molecules in the endometrial carcinoma tissues and found that HSPA8 was most significantly upregulated. We further validated the overexpression of HSPA8 by using immunoblot analysis. Then, HSPA8 siRNA was transferred into the endometrial cancer cells RL-95-2 and HEC-1B. The depletion of HSPA8 siRNAs significantly reduced cell proliferation, promoted cell apoptosis, and suppressed cell growth in both cell lines. Taken together, HSPA8 plays a vital role in the development of endometrial carcinoma. HSPA8 is a candidate biomarker for early diagnosis and therapy of Stage I endometrial carcinoma.

β2-adrenergic receptor signaling promotes pancreatic ductal adenocarcinoma (PDAC) progression through facilitating PCBP2-dependent c-myc expression

The β2-adrenergic receptor (β2-AR) plays a crucial role in pancreatic ductal adenocarcinoma (PDAC) progression. In this report, we identified poly(rC)-binding protein 2 (PCBP2) as a novel binding partner for β2-AR using immunoprecipitation-mass spectrometry (IP-MS) approach. The association between β2-AR and PCBP2 was verified using reciprocal immunoprecipitation. Importantly, we found significant interaction and co-localization of the two proteins in the presence of β2-AR agonist in Panc-1 and Bxpc3 PDAC cells. β2-AR-induced recruitment of PCBP2 led to augmented protein level of c-myc in PDAC cells, likely as a result of enhanced internal ribosome entry segment (IRES)-mediated translation of c-myc. The activation of β2-AR accelerated cell proliferation and colony formation, while knockdown of PCBP2 or c-myc restrained the effect. Furthermore, overexpression of PCBP2 was observed in human PDAC cell lines and tissue specimens compared to the normal pancreatic ductal epithelial cells and the non-cancerous tissues respectively. Overexpression of β2-AR and PCBP2 was associated with advanced tumor stage and significantly worsened prognosis in patients with PDAC. Our results elucidate a new molecular mechanism by which β2-AR signaling facilitates PDAC progression through triggering PCBP2-dependent c-myc expression.

Is miR-34a a Well-equipped Swordsman to Conquer Temple of Molecular Oncology?

Overwhelmingly increasing advancements in miRNA biology have opened new avenues for pharmaceutical companies to initiate studies on designing effective, safe, and therapeutically active candidates using miRNA mimetics and miRNA inhibitors. In accordance with this approach, development of miravirsen and SPC3649, an LNA-based (locked nucleic acid) antisense molecule against miR-122, to treat hepatitis C has sparked interest in identifying most efficient microRNAs for journey from bench-top toward pharmaceutical industry and breakthroughs in delivery technology will pave the way to 'final frontier'. MRX34, a liposome-formulated mimic of miR-34 for treatment of metastatic cancer with liver involvement and unresectable primary liver cancer, has also entered in clinical trial. There is a successive increase in the research work related to miR-34 biology and miRNA regulation of modulators of intracellular signaling cascades. We partition this review into how miR-34a is regulated by different proteins and how Wnt- and TGF-induced intracellular signaling cascades are modulated by miR-34a. In this review, we bring to limelight how miR-34a regulates its target genes to induce apoptosis and inhibit cell proliferation as evidenced by in vitro and in vivo analysis. We also discuss miR-34 regulation of PDGFR and c-MET and recent advancements in nanotechnologically delivered miR-34a. Spotlight is also set on modulation of chemotherapeutic sensitivity by miR-34a in cancer cells using reconstruction studies. Clinical trial of miR-34 is indicative of its tremendous potential, and continuous cutting research will prove to be effective in efficiently translating laboratory findings into clinically effective therapeutics.

Regulation of Stem Cell Self-Renewal and Oncogenesis by RNA-Binding Proteins

Throughout their life span, multicellular organisms rely on stem cell systems. During development pluripotent embryonic stem cells give rise to all cell types that make up the organism. After birth, tissue stem cells maintain properly functioning tissues and organs under homeostasis as well as promote regeneration after tissue damage or injury. Stem cells are capable of self-renewal, which is the ability to divide indefinitely while retaining the potential of differentiation into multiple cell types. The ability to self-renew, however, is a double-edged sword; the molecular mechanisms of self-renewal can be a target of malignant transformation driving tumor development and progression. Growing lines of evidence have shown that RNA-binding proteins (RBPs) play pivotal roles in the regulation of self-renewal by modulating metabolism of coding and non-coding RNAs both in normal tissues and in cancers. In this review, we discuss our current understanding of tissue stem cell systems and how RBPs regulate stem cell fates as well as how the regulatory functions of RBPs contribute to oncogenesis.

Downregulated Poly-C binding protein-1 is a novel predictor associated with poor prognosis in Acute Myeloid Leukemia

Background

Depletion of Poly-C binding protein-1(PCBP1) is implicated in various human malignancies. However, the underlying biological effect of PCBP1 in cancers, including acute myeloid leukemia (AML), still remains elusive. The purpose of this study was to examine the expression and clinical outcome of PCBP1in acute myeloid leukemia.

Methods

Bone marrow fluids of 88 newly diagnosed AML patients were sampled, and the PCBP1 mRNA expression level was evaluated using quantitative RT-PCR. The association between PCBP1 expression and clinicopathological features or the survival status of the patients was assessed by Chi-square test and Kaplan-Meier method.

Results

Comparing newly diagnosed AML patients to normal healthy donors, PCBP1 expression was significantly decreased in AML patients (P < 0.001). Conversely, PCBP1 expression had accordingly recovered back to normal in patients with complete remission (P < 0.001). Clinical feature analyses showed that PCBP1 expression was negatively correlated with white blood cell count (P = 0.024). In addition, patients with low PCBP1 expression had poor disease-free survival (11.8 % vs. 45.3 %; P = 0.01) and overall survival (18.2 % vs. 42.4 %; P = 0.032), respectively.

Conclusions

Taken together, our results showed for the first time that expression of PCBP1 was down-regulated in newly diagnosed AML patients and might be an independent prognostic marker in AML and should to be further investigated.

Spatiotemporal Expression of Poly(rC)-Binding Protein PCBP2 Modulates Schwann Cell Proliferation After Sciatic Nerve Injury

Poly(C)-binding proteins (PCBPs), also known as RNA-binding proteins, interact in a sequence-specific fashion with single-stranded poly(C). It was reported that PCBP2 contributed to gastric cancer proliferation and survival through miR-34a, and knockdown of PCBP2 inhibited glioma proliferation through inhibition of cell cycle progression. In addition, PCBP2 might play a critical role in the regulation of cortical neurons apoptosis induced by hypoxia or ischemia. Because of the essential role of PCBP2 in nervous system and cell growth, we investigated the spatiotemporal expression of PCBP2 in a rat sciatic nerve crush (SNC) model. We detected the upregulated expression of PCBP2 in Schwann cell after SNC. Besides, the peak expression of PCBP2 was in parallel with proliferation cell nuclear antigen. In vitro, we observed increased expression of PCBP2 during the process of TNF-α-induced Schwann cell proliferation. Specially, PCBP2-specific siRNA-transfected Schwann cell showed significantly decreased ability for proliferation. Together, all these data indicated that the change of PCBP2 protein expression was associated with Schwann cell proliferation after the trauma of the peripheral nervous system.

Anti-Proliferative Effect of Rosmarinus officinalis L. Extract on Human Melanoma A375 Cells

Rosemary (Rosmarinus officinalis L.) has been used since ancient times in traditional medicine, while nowadays various rosemary formulations are increasingly exploited by alternative medicine to cure or prevent a wide range of health disorders. Rosemary’s bioproperties have prompted scientific investigation, which allowed us to ascertain antioxidant, anti-inflammatory, cytostatic, and cytotoxic activities of crude extracts or of pure components. Although there is a growing body of experimental work, information about rosemary’s anticancer properties, such as chemoprotective or anti-proliferative effects on cancer cells, is very poor, especially concerning the mechanism of action. Melanoma is a skin tumor whose diffusion is rapidly increasing in the world and whose malignancy is reinforced by its high resistance to cytotoxic agents; hence the availability of new cytotoxic drugs would be very helpful to improve melanoma prognosis. Here we report on the effect of a rosemary hydroalcoholic extract on the viability of the human melanoma A375 cell line. Main components of rosemary extract were identified by liquid chromatography coupled to tandem mass spectrometry (LC/ESI-MS/MS) and the effect of the crude extract or of pure components on the proliferation of cancer cells was tested by MTT and Trypan blue assays. The effect on cell cycle was investigated by using flow cytometry, and the alteration of the cellular redox state was evaluated by intracellular ROS levels and protein carbonylation analysis. Furthermore, in order to get information about the molecular mechanisms of cytotoxicity, a comparative proteomic investigation was performed.

Iron Toxicity in the Retina Requires Alu RNA and the NLRP3 Inflammasome

Excess iron induces tissue damage and is implicated in age-related macular degeneration (AMD). Iron toxicity is widely attributed to hydroxyl radical formation through Fenton's reaction. We report that excess iron, but not other Fenton catalytic metals, induces activation of the NLRP3 inflammasome, a pathway also implicated in AMD. Additionally, iron-induced degeneration of the retinal pigmented epithelium (RPE) is suppressed in mice lacking inflammasome components caspase-1/11 or Nlrp3 or by inhibition of caspase-1. Iron overload increases abundance of RNAs transcribed from short interspersed nuclear elements (SINEs): Alu RNAs and the rodent equivalent B1 and B2 RNAs, which are inflammasome agonists. Targeting Alu or B2 RNA prevents iron-induced inflammasome activation and RPE degeneration. Iron-induced SINE RNA accumulation is due to suppression of DICER1 via sequestration of the co-factor poly(C)-binding protein 2 (PCBP2). These findings reveal an unexpected mechanism of iron toxicity, with implications for AMD and neurodegenerative diseases associated with excess iron.