Silencing of Ribosomal Protein L34 (RPL34) Inhibits the Proliferation and Invasion of Esophageal Cancer Cells

Fisetin nanoparticles based on cells cycle and apoptosis intervention for the treatment of lymphoma and leukemia

Lymphoma and leukemia are both hematological system tumors with complex etiology, and mainly treated with chemotherapeutic drugs. However, therapeutic drugs can interrupt curative effect due to different side effects. Therefore, it is worthwhile to develop a novel therapeutic for providing insights for clinical tumor treatment. In this study, we developed a fisetin nanoparticles (Fisetin NPs) through a self-assembled method, and investigated the activity and potential mechanism of Fisetin NPs against lymphoma and leukemia. The spherical and uniformly distributed Fisetin NPs effectively inhibited both tumor cells proliferation, arrested EL4 cells G0/G1 phase and K562 cells G2/M phase, and induced apoptosis in vitro. In vivo, Fisetin NPs exhibited excellent tumor growth inhibition, effective inhibition of cell proliferation and angiogenesis, significant induction of apoptosis and ideal safety. Mechanically, fisetin upregulated genes (Fas, Pidd, Puma, Apaf1, and p21) in the p53 signaling pathway and bound to N-acetyltransferase 10 (NAT10), ribosomal protein L34 (RPL34) and GTP binding protein 4 (GTPBP4). Collectively, Fisetin NPs have promising therapeutic effects on lymphoma and leukemia, which are of great significant for clinical implications.

Identification of potential biomarkers and infiltrating immune cells from scalp psoriasis

BACKGROUND

Scalp psoriasis seriously affects the appearance and psychological status of patients. The aim of this study was to investigate the effect and potential mechanism of RPL9 and TIFA in scalp psoriasis, so as to provide a precise and effective way for the clinical treatment of scalp psoriasis.

METHODS

The Gene Expression Omnibus (GEO) database was employed to download the GSE75343 dataset to search for differentially expressed genes (DEGs) in scalp psoriasis through Sangerbox. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) enrichment analysis, functional enrichment analysis, immune cell infiltration analysis, immune responses and correlation analysis with 12 hub genes were performed. Then, STRING was used to develop a protein-protein interaction (PPI) network, used Cytoscape to locate hub genes, and SVM-RFE and random forest were utilized to identified RPL9 as the targeted gene. TIFA-RPL9 interaction predictions were made viathe Open Targets Platform and Uniprot. Further, the RPL9 and TIFA expression, molecular mechanism, and function were assessed in scalp psoriasis.

RESULTS

Immunohistochemistry, qPCR, and western blotting verified that RPL9 and TIFA were highly expressed in lesional tissues of scalp psoriasis and IL17A-stimulated HaCaT cells. RPL9 knockdown effectively suppressed the proliferative capacity of IL17A-stimulated HaCaT cells in the CCK8 assay. The co-immunoprecipitation results revealed that RPL9 could interact with TIFA in IL17A-stimulated HaCaT cells. In qPCR and western blotting, RPL9 knockdown significantly inhibited TIFA at the mRNA and protein levels in IL17A-stimulated HaCaT cells. In ELISA, the secretion of TNF-α was markedly inhibited after downregulating RPL9 in IL17A-stimulated HaCaT cells.

CONCLUSION

To our knowledge, we have elucidated the expression and role of RPL9 and TIFA in scalp psoriatic skin and keratinocytes, and our findings confirm that RPL9 might act as a candidate therapeutic target for scalp psoriasis.

The role of dysregulated mRNA translation machinery in cancer pathogenesis and therapeutic value of ribosome-inactivating proteins

Dysregulated protein synthesis is a hallmark of tumors. mRNA translation reprogramming contributes to tumorigenesis, which is fueled by abnormalities in ribosome formation, tRNA abundance and modification, and translation factors. Not only malignant cells but also stromal cells within tumor microenvironment can undergo transformation toward tumorigenic phenotypes during translational reprogramming. Ribosome-inactivating proteins (RIPs) have garnered interests for their ability to selectively inhibit protein synthesis and suppress tumor growth. This review summarizes the role of dysregulated translation machinery in tumor development and explores the potential of RIPs in cancer treatment.

Artificial Downregulation of Ribosomal Protein L34 Restricts the Proliferation and Metastasis of Colorectal Cancer by Suppressing the JAK2/STAT3 Signaling Pathway

The highly conserved ribosomal protein L34 (RPL34) has been reported to play an essential role in the progression of diverse malignancies. RPL34 is aberrantly expressed in multiple cancers, although its significant in colorectal cancer (CRC) is currently unclear. Here, we demonstrated that RPL34 expression was higher in CRC tissues than in normal tissues. Upon RPL34 overexpression, the ability of proliferation, migration, invasion, and metastasis of CRC cells were significantly enhanced in vitro and in vivo. Furthermore, high expression of RPL34 accelerated cell cycle progression, activated the JAK2/STAT3 signaling pathway, and induced the epithelial-to-mesenchymal transition (EMT) program. Conversely, RPL34 silencing inhibited the CRC malignant progression. Utilizing immunoprecipitation assays, we identified the RPL34 interactor, the cullin-associated NEDD8-dissociated protein 1 (CAND1), which is a negative regulator of cullin-RING ligases. CAND1 overexpression reduced the ubiquitin level of RPL34 and stabilized RPL34 protein. CAND1 silencing in CRC cells resulted in a decrease in the ability of proliferation, migration, and invasion. CAND1 overexpression promoted CRC malignant phenotypes and induced EMT, and RPL34 knockdown rescued CAND1-induced CRC progression. In summary, our study indicates that RPL34 acts as a mediator, is stabilized by CAND1, and promotes proliferation and metastasis, in part, through the activation of the JAK2/STAT3 signaling pathway and induction of EMT in CRC.

Identifying Hub Genes Associated with Neoadjuvant Chemotherapy Resistance in Breast Cancer and Potential Drug Repurposing for the Development of Precision Medicine

Breast cancer is the second leading cause of morbidity and mortality in women worldwide. Despite advancements in the clinical application of neoadjuvant chemotherapy (NAC), drug resistance remains a major concern hindering treatment efficacy. Thus, identifying the key genes involved in driving NAC resistance and targeting them with known potential FDA-approved drugs could be applied to advance the precision medicine strategy. With this aim, we performed an integrative bioinformatics study to identify the key genes associated with NAC resistance in breast cancer and then performed the drug repurposing to identify the potential drugs which could use in combination with NAC to overcome drug resistance. In this study, we used publicly available RNA-seq datasets from the samples of breast cancer patients sensitive and resistant to chemotherapy and identified a total of 1446 differentially expressed genes in NAC-resistant breast cancer patients. Next, we performed gene co-expression network analysis to identify significantly co-expressed gene modules, followed by MCC (Multiple Correlation Clustering) clustering algorithms and identified 33 key hub genes associated with NAC resistance. mRNA–miRNA network analysis highlighted the potential impact of these hub genes in altering the regulatory network in NAC-resistance breast cancer cells. Further, several hub genes were found to be significantly involved in the poor overall survival of breast cancer patients. Finally, we identified FDA-approved drugs which could be useful for potential drug repurposing against those hub genes. Altogether, our findings provide new insight into the molecular mechanisms of NAC resistance and pave the way for drug repurposing techniques and personalized treatment to overcome NAC resistance in breast cancer.

Cryo-EM structure and rRNA modification sites of a plant ribosome

Protein synthesis in crop plants contributes to the balance of food and fuel on our planet, which influences human metabolic activity and lifespan. Protein synthesis can be regulated with respect to changing environmental cues via the deposition of chemical modifications into rRNA. Here, we present the structure of a plant ribosome from tomato and a quantitative mass spectrometry analysis of its rRNAs. The study reveals fine features of the ribosomal proteins and 71 plant-specific rRNA modifications, and it re-annotates 30 rRNA residues in the available sequence. At the protein level, isoAsp is found in position 137 of uS11, and a zinc finger previously believed to be universal is missing from eL34, suggesting a lower effect of zinc deficiency on protein synthesis in plants. At the rRNA level, the plant ribosome differs markedly from its human counterpart with respect to the spatial distribution of modifications. Thus, it represents an additional layer of gene expression regulation, highlighting the molecular signature of a plant ribosome. The results provide a reference model of a plant ribosome for structural studies and an accurate marker for molecular ecology.

Epithelial-Mesenchymal Transition-Mediated Tumor Therapeutic Resistance

Cancer is one of the world’s most burdensome diseases, with increasing prevalence and a high mortality rate threat. Tumor recurrence and metastasis due to treatment resistance are two of the primary reasons that cancers have been so difficult to treat. The epithelial–mesenchymal transition (EMT) is essential for tumor drug resistance. EMT causes tumor cells to produce mesenchymal stem cells and quickly adapt to various injuries, showing a treatment-resistant phenotype. In addition, multiple signaling pathways and regulatory mechanisms are involved in the EMT, resulting in resistance to treatment and hard eradication of the tumors. The purpose of this study is to review the link between EMT, therapeutic resistance, and the molecular process, and to offer a theoretical framework for EMT-based tumor-sensitization therapy.

Suppression of RPL34 Inhibits Tumor Cell Proliferation and Promotes Apoptosis in Glioblastoma

Accumulating evidence indicates Ribosomal protein 34 (RPL34) promotes tumor malignance and its expression is associated with poor prognosis in multiple cancer cells. However, the physiological role and biological mechanism of RPL34 in glioblastoma (GBM) remain unclear. Hence, this study aimed to investigate the expression and the role of RPL34 in GBM. A total of 59 glioma samples and 12 normal brains for epilepsy surgery were used to determine the underlying mechanisms and the biological behaviors of RPL34 in GBM. In this study, we identified that RPL34 expression was significantly (p < 0.05) enriched in GBM tumors compared with low-grade glioma and normal brain, and its expression was associated with poor survival. Additionally, RPL34 was functionally required for tumor proliferation in vitro. Mechanically, inhibition of RPL34 induced glioma cell apoptosis by activation of Bad/Caspase7/PARP signaling pathway. The RPL34 promotes cell survival in GBM and could be a potential therapeutic target for GBM.

Deregulation of ribosomal proteins in human cancers

The ribosome, the site for protein synthesis, is composed of ribosomal RNAs (rRNAs) and ribosomal proteins (RPs). The latter have been shown to have many ribosomal and extraribosomal functions. RPs are implicated in a variety of pathological processes, especially tumorigenesis and cell transformation. In this review, we will focus on the recent advances that shed light on the effects of RPs deregulation in different types of cancer and their roles in regulating the tumor cell fate.

Ribosomal proteins and human diseases: molecular mechanisms and targeted therapy

Ribosome biogenesis and protein synthesis are fundamental rate-limiting steps for cell growth and proliferation. The ribosomal proteins (RPs), comprising the structural parts of the ribosome, are essential for ribosome assembly and function. In addition to their canonical ribosomal functions, multiple RPs have extra-ribosomal functions including activation of p53-dependent or p53-independent pathways in response to stress, resulting in cell cycle arrest and apoptosis. Defects in ribosome biogenesis, translation, and the functions of individual RPs, including mutations in RPs have been linked to a diverse range of human congenital disorders termed ribosomopathies. Ribosomopathies are characterized by tissue-specific phenotypic abnormalities and higher cancer risk later in life. Recent discoveries of somatic mutations in RPs in multiple tumor types reinforce the connections between ribosomal defects and cancer. In this article, we review the most recent advances in understanding the molecular consequences of RP mutations and ribosomal defects in ribosomopathies and cancer. We particularly discuss the molecular basis of the transition from hypo- to hyper-proliferation in ribosomopathies with elevated cancer risk, a paradox termed "Dameshek's riddle." Furthermore, we review the current treatments for ribosomopathies and prospective therapies targeting ribosomal defects. We also highlight recent advances in ribosome stress-based cancer therapeutics. Importantly, insights into the mechanisms of resistance to therapies targeting ribosome biogenesis bring new perspectives into the molecular basis of cancer susceptibility in ribosomopathies and new clinical implications for cancer therapy.

The Ribosomal Protein L28 Gene Induces Sorafenib Resistance in Hepatocellular Carcinoma

Background

Sorafenib is the first molecular-targeted drug for the treatment of advanced hepatocellular carcinoma (HCC). However, its treatment efficiency decreases after a short period of time because of the development of drug resistance. This study investigates the role of key genes in regulating sorafenib-resistance and elucidates the mechanism of drug resistance in hepatocellular carcinoma.

Methods

The HCC HepG2 cells were used to generate a sorafenib-resistant cell model by culturing the cells in gradually increasing concentration of sorafenib. RNA microarray was applied to profile gene expression and screen key genes associated with sorafenib resistance. Specific targets were knockdown in sorafenib-resistant HepG2 cells for functional studies. The HCC model was established in ACI rats using Morris hepatoma3924A cells to validate selected genes associated with sorafenib resistance in vivo.

Results

The HepG2 sorafenib-resistant cell model was successfully established. The IC₅₀ of sorafenib was 9.988μM in HepG2 sorafenib-resistant cells. A total of 35 up-regulated genes were detected by expression profile chip. High-content screening technology was used and a potential drug-resistance related gene RPL28 was filtered out. After knocking down RPL28 in HepG2 sorafenib-resistant cells, the results of cell proliferation and apoptosis illustrated that RPL28 is the key gene involving in drug resistance. Furthermore, it was found that both RNA and protein expression of RPL28 increased in HepG2 sorafenib-resistant specimens of Morris Hepatoma rats. In addition, the expression of proliferative protein Ki-67 increased in sorafenib-resistant cells.

Conclusion

Our study suggested that RPL28 is a key gene inducing sorafenib resistance in HCC and could be a potential target for the treatment of drug-resistant HCC.

Silencing Ribosomal Protein L22 Promotes Proliferation and Migration, and Inhibits Apoptosis of Gastric Cancer Cells by Regulating the Murine Double Minute 2-Protein 53 (MDM2-p53) Signaling Pathway

Background

The aim of this study was to investigate the effect of ribosomal protein L22 (RPL22) on gastric cancer (GC) cell proliferation, migration, and apoptosis, and its correlation with the murine double minute 2-protein 53 (MDM2-p53) signaling pathway.

Material/Methods

The RPL22 expression in GC tissues and cells was detected by quantitative reverse transcription-polymerase chain reaction and western blotting. RPL22 was overexpressed in the MKN-45 cells by the transfection of a vector, pcDNA3.1 (pcDNA)-RPL22, whereas it was silenced in the MGC-803 cells by the transfection of short interfering (si) RNA (si-RPL22). Flow cytometric analysis, cell viability assays, wound healing assays, and transwell assays were utilized to explore the influences of RPL22 on the apoptosis, proliferation, migration, and invasion. Nutlin-3 (an MDM2-p53 inhibitor) was used to inhibit MDM2-p53 signaling.

Results

The RPL22 expression was downregulated in GC tissues and cells. It was significantly lower in the advanced GC tissues than in the early GC tissues, and was significantly lower in the lymphatic metastatic tissues than in the non-lymphatic metastatic tissues. The transfection of si-RPL22 accelerated the ability of GC cells to proliferate and metastasize, whereas apoptosis was dampened. The transfection of pcDNA-RPL22 exerted the opposite effect on the GC cells; MDM2 expression was upregulated in RPL22-silenced GC cells, while the expression of p53 was downregulated. In vitro, treatment with nutlin-3 reversed the promoting effects of si-RPL22 on GC progression.

Conclusions

In vitro, the silencing of RPL22 aggravates GC by regulating the MDM2-p53 signaling pathway.

Dual Inhibition of DKC1 and MEK1/2 Synergistically Restrains the Growth of Colorectal Cancer Cells

Colorectal cancer, one of the most commonly diagnosed cancers worldwide, is often accompanied by uncontrolled proliferation of tumor cells. Dyskerin pseudouridine synthase 1 (DKC1), screened using the genome-wide RNAi strategy, is a previously unidentified key regulator that promotes colorectal cancer cell proliferation. Enforced expression of DKC1, but not its catalytically inactive mutant D125A, accelerates cell growth in vitro and in vivo. DKC1 knockdown or its inhibitor pyrazofurin attenuates cell proliferation. Proteomics, RNA immunoprecipitation (RIP)-seq, and RNA decay analyses reveal that DKC1 binds to and stabilizes the mRNA of several ribosomal proteins (RPs), including RPL10A, RPL22L1, RPL34, and RPS3. DKC1 depletion significantly accelerates mRNA decay of these RPs, which mediates the oncogenic function of DKC1. Interestingly, these DKC1-regulated RPs also interact with HRAS and suppress the RAS/RAF/MEK/ERK pathway. Pyrazofurin and trametinib combination synergistically restrains colorectal cancer cell growth in vitro and in vivo. Furthermore, DKC1 is markedly upregulated in colorectal cancer tissues compared to adjacent normal tissues. Colorectal cancer patients with higher DKC1 expression has consistently poorer overall survival and progression-free survival outcomes. Taken together, these data suggest that DKC1 is an essential gene and candidate therapeutic target for colorectal cancer.

RPL34-AS1-induced RPL34 inhibits cervical cancer cell tumorigenesis via the MDM2-P53 pathway

Ribosomal proteins (RPs) are important components of ribosomes and related to the occurrence and development of tumors. However, little is known about the effects of the RP network on cervical cancer (CC). In this study, we screened differentially expressed RPL34 in CC by high‐throughput quantitative proteome assay. We found that RPL34 acted as a tumor suppressor and was downregulated in CC and inhibited the proliferation, migration, and invasion abilities of CC cells. Next, we verified that RPL34 regulated the CC through the MDM2‐P53 pathway by using Act D medicine, MDM2 inhibitor, and a series of western blotting（WB）assays. Moreover, an antisense lncRNA, RPL34‐AS1, regulated the expression of RPL34 and participated in the tumorigenesis of CC. RPL34 can reverse the effect of RPL34‐AS1 in CC cells. Finally, by RNA‐binding protein immunoprecipitation (RIP) assay we found that eukaryotic initiation factor 4A3 (EIF4A3), which binds to RPL34‐AS1, regulated RPL34‐AS1 expression in CC. Therefore, our findings indicate that RPL34‐AS1–induced RPL34 inhibits CC cell proliferation, invasion, and metastasis through modulation of the MDM2‐P53 signaling pathway, which provides a meaningful target for the early diagnosis and treatment of CC.

microRNAs Mediated Regulation of the Ribosomal Proteins and its Consequences on the Global Translation of Proteins

Ribosomal proteins (RPs) are mostly derived from the energy-consuming enzyme families such as ATP-dependent RNA helicases, AAA-ATPases, GTPases and kinases, and are important structural components of the ribosome, which is a supramolecular ribonucleoprotein complex, composed of Ribosomal RNA (rRNA) and RPs, coordinates the translation and synthesis of proteins with the help of transfer RNA (tRNA) and other factors. Not all RPs are indispensable; in other words, the ribosome could be functional and could continue the translation of proteins instead of lacking in some of the RPs. However, the lack of many RPs could result in severe defects in the biogenesis of ribosomes, which could directly influence the overall translation processes and global expression of the proteins leading to the emergence of different diseases including cancer. While microRNAs (miRNAs) are small non-coding RNAs and one of the potent regulators of the post-transcriptional gene expression, miRNAs regulate gene expression by targeting the 3' untranslated region and/or coding region of the messenger RNAs (mRNAs), and by interacting with the 5' untranslated region, and eventually finetune the expression of approximately one-third of all mammalian genes. Herein, we highlighted the significance of miRNAs mediated regulation of RPs coding mRNAs in the global protein translation.

Ribosomal protein L34 is a potential prognostic biomarker and therapeutic target in hilar cholangiocarcinoma

Background

Ribosomal protein 34 (RPL34) is a highly conserved protein belonging to the 60S large subunit of mammalian ribosomes that has been found to be dysregulated in a variety of human tumors. However, there are limited results that illuminate the role and expression profiles of RPL34 in hilar cholangiocarcinoma (HCCA).

Methods

RPL34 expression was detected in human HCCA by immunohistochemistry. The relationship of RPL34 expression with clinical outcomes was evaluated by univariate and multivariate analyses. The effect of RPL34 on cell migration and tumor growth was detected after silencing endogenous RPL34 expression.

Results

RPL34 was overexpressed in HCCA compared with normal tissue samples and correlated significantly with regional lymph node metastasis and poorly/undifferentiated tumors. Patients with high RPL34 expression had a shorter time to recur and a poorer outcome than those without RPL34 expression. Silencing RPL34 inhibited cell proliferation and migration in vitro and upregulated E-cadherin. Silencing RPL34 also attenuated tumor growth in vivo.

Conclusions

Our findings suggested that RPL34 might serve as a promising prognostic biomarker and a potential therapeutic target for the treatment of HCCA.

Biological effect of ribosomal protein L32 on human breast cancer cell behavior

Breast cancer (BC) is the most common malignancy among women worldwide. However, identifying effective biomarkers for the diagnosis and treatment of BC is challenging. Based on our previously developed 'humanized' mouse model of BC, microarray expression analysis was performed and multiple differentially expressed genes, including ribosomal protein (RP) L32, were screened. Recent reports have revealed that RPs are relevant to the development and progression of cancer. However, the expression and function of RPL32 in BC remains unknown. Therefore, in the present study, the role of RPL32 in the development of BC was explored. Immunohistochemical staining and reverse transcription‑quantitative PCR were used, and it was found that RPL32 was upregulated in human BC tissues and cells. Cell Counting Kit‑8, cell invasion and migration assays were performed, which demonstrated that RPL32 knockdown using lentivirus‑delivered small interfering RNA inhibited the migration and invasion of BC cells in vitro and in vivo (nude mouse model). Moreover, western blotting showed that RPL32 knockdown decreased the expression levels of matrix metalloproteinase (MMP)‑2 and MMP‑9. Thus, the present findings indicated a potential oncogenic role of RPL32, suggesting that it may be a novel target for molecular targeted therapy in patients with BC.

Quercetin Inhibits the Proliferation and Aflatoxins Biosynthesis of Aspergillus flavus

In this work of quercetin’s anti-proliferation action on A. flavus, we revealed that quercetin can effectively hamper the proliferation of A. flavus in dose-effect and time-effect relationships. We tested whether quercetin induced apoptosis in A. flavus via various detection methods, such as phosphatidylserine externalization and Hoechst 33342 staining. The results showed that quercetin had no effect on phosphatidylserine externalization and cell nucleus in A. flavus. Simultaneously, quercetin reduced the levels of reactive oxygen species (ROS). For a better understanding of the molecular mechanism of the A. flavus response to quercetin, the RNA-Seq was used to explore the transcriptomic profiles of A. flavus. According to transcriptome sequencing data, quercetin inhibits the proliferation and aflatoxin biosynthesis by regulating the expression of development-related genes and aflatoxin production-related genes. These results will provide some theoretical basis for quercetin as an anti-mildew agent resource.

The roles of moonlight ribosomal proteins in the development of human cancers

"Moonlighting protein" is a term used to define a single protein with multiple functions and different activities that are not derived from gene fusions, multiple RNA splicing, or the proteolytic activity of promiscuous enzymes. Different proteinous constituents of ribosomes have been shown to have important moonlighting extra-ribosomal functions. In this review, we introduce the impact of key moonlight ribosomal proteins and dependent signal transduction in the initiation and progression of various cancers. As a future perspective, the potential role of these moonlight ribosomal proteins in the diagnosis, prognosis, and development of novel strategies to improve the efficacy of therapies for human cancers has been suggested.

Knockdown of RPL34 inhibits the proliferation and migration of glioma cells through the inactivation of JAK/STAT3 signaling pathway

Ribosomal protein L34 (RPL34), belonging to the L34E family of ribosomal proteins, was reported to be dysregulated in several types of cancers and plays important roles in tumor progression. However, the expression and roles of RPL34 in human glioma remain largely unknown. Thus, the objective of this study was to investigate the expression and role of RPL34 in glioma. We report here that RPL34 is highly expressed in human glioma tissues and cell lines. Knockdown of RPL34 markedly inhibited the proliferation, migration, and invasion, as well as prevented the epithelial-mesenchymal transition phenotype in glioma cells. Further, mechanistic analysis showed that knockdown of RPL34 significantly downregulated the levels of p-JAK and p-STAT3 in glioma cells. Taken together, our findings indicated that knockdown of RPL34 inhibits the proliferation and migration of glioma cells through the inactivation of JAK/STAT3 signaling pathway. Thus, RPL34 may serve as a potential therapeutic target for the treatment of glioma.

The nucleolus, an ally, and an enemy of cancer cells

The rates of ribosome production by a nucleolus and of protein biosynthesis by ribosomes are tightly correlated with the rate of cell growth and proliferation. All these processes must be matched and appropriately regulated to provide optimal cell functioning. Deregulation of certain factors, including oncogenes, controlling these processes, especially ribosome biosynthesis, can lead to cell transformation. Cancer cells are characterized by intense ribosome biosynthesis which is advantageous for their growth and proliferation. On the other hand, this feature can be engaged as an anticancer strategy. Numerous nucleolar factors such as nucleolar and ribosomal proteins as well as different RNAs, in addition to their role in ribosome biosynthesis, have other functions, including those associated with cancer biology. Some of them can contribute to cell transformation and cancer development. Others, under stress evoked by different factors which often hamper function of nucleoli and thus induce nucleolar/ribosomal stress, can participate in combating cancer cells. In this sense, intentional application of therapeutic agents affecting ribosome biosynthesis can cause either release of these molecules from nucleoli or their de novo biosynthesis to mediate the activation of pathways leading to elimination of harmful cells. This review underlines the role of a nucleolus not only as a ribosome constituting apparatus but also as a hub of both positive and negative control of cancer development. The article is mainly based on original papers concerning mechanisms in which the nucleolus is implicated directly or indirectly in processes associated with neoplasia.

Diagnostic and prognostic implications of ribosomal protein transcript expression patterns in human cancers

Background

Ribosomes, the organelles responsible for the translation of mRNA, are comprised of four rRNAs and ~ 80 ribosomal proteins (RPs). Although canonically assumed to be maintained in equivalent proportions, some RPs have been shown to possess differential expression across tissue types. Dysregulation of RP expression occurs in a variety of human diseases, notably in many cancers, and altered expression of some RPs correlates with different tumor phenotypes and patient survival. Little work has been done, however, to characterize overall patterns of RP transcript (RPT) expression in human cancers.

Methods

To investigate the impact of global RPT expression patterns on tumor phenotypes, we analyzed RPT expression of ~ 10,000 human tumors and over 700 normal tissues from The Cancer Genome Atlas (TCGA) using t-distributed stochastic neighbor embedding (t-SNE). Clusters of tumors identified by t-SNE were then analyzed with chi-squared and t-tests to compare phenotypic data, ANOVA to compare individual RPT expression, and Kaplan-Meier curves to assess survival differences.

Results

Normal tissues and cancers possess distinct and readily discernible RPT expression patterns that are independent of their absolute levels of expression. In tumors, RPT patterning is distinct from that of normal tissues, identifies heretofore unrecognized tumor subtypes, and in many cases correlates with molecular, pathological, and clinical features, including survival.

Conclusions

RPT expression patterns are both tissue-specific and tumor-specific. These could be used as a powerful and novel method of tumor classification, offering a potential clinical tool for prognosis and therapeutic stratification.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4178-z) contains supplementary material, which is available to authorized users.

Influence of the RPL34 gene on the growth and metastasis of oral squamous cell carcinoma cells

BACKGROUND

Oral squamous cell carcinoma (OSCC) accounts for almost 3% of all malignant tumors all over the world. This study aims to investigate the correlation of RPL34 with the cell growth and metastasis of oral squamous cell carcinoma (OSCC) as well as its clinical prognosis.

METHOD

Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry were conducted to determine the RPL34 expression in 85 OSCC tissues and 30 normal oral mucosa tissues. Besides, OSCC cell lines SCC-4 were divided into blank group, negative control (NC) group and RPL34-shRNA group. The qRT-PCR and western blot were performed to measure RPL34 expression, CCK-8 and flow cytometry to observe cell growth and apoptosis, and wound healing and transwell to detect cell migration and invasion.

RESULTS

The RPL34 gene expression was up-regulated in OSCC tissues and cells. The RPL34 expression was significantly correlated with differentiation degree, TNM stage and lymph node metastasis. Patients with positive RPL34 expression had a poorer prognosis. After inhibition of RPL34 expression, the proliferation of SCC-4 cells was slowed down at 24h, 48h, 72h and 96h respectively, and both the migration distance and the number of invasive cells were reduced, while there was an increase in the ratio of cells at G0/G1 stage and cell apoptosis.

CONCLUSION

The RPL34 gene was highly expressed in OSCC, while silencing RPL34 could block cell proliferation and metastasis, but promote cell apoptosis, suggesting the RPL34 gene to be a new promising clinical target for OSCC therapy.