Programmed cell death 4: A novel player in the pathogenesis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a pathological condition recognized by menstrual cycle irregularities, androgen excess, and polycystic ovarian morphology, affecting a significant proportion of women of childbearing age and accounting for the most prevalent cause of anovulatory sterility. In addition, PCOS is frequently accompanied by metabolic and endocrine disturbances such as obesity, dyslipidemia, insulin resistance, and hyperinsulinemia, indicating the multiplicity of mechanisms implicated in the progression of PCOS. However, the exact pathogenesis of PCOS is yet to be elucidated. Programmed cell death 4 (PDCD4) is a ubiquitously expressed protein that contributes to the regulation of various cellular processes, including gene expression, cell cycle progression, proliferation, and apoptosis. Despite some disparities concerning its exact cellular effects, PDCD4 is generally characterized as a protein that inhibits cell cycle progression and proliferation and instead drives the cell into apoptosis. The apoptosis of granulosa cells (GCs) is speculated to take a major part in the occurrence and progression of PCOS by ceasing antral follicle development and compromising oocyte competence. Given the possible involvement of GC apoptosis in the progression of PCOS, as well as the contribution of PDCD4 to the regulation of cell apoptosis and the development of metabolic diseases, the current review aimed to discuss whether or how PDCD4 can play a role in the pathogenesis of PCOS by affecting GC apoptosis.

miR-590-5p may regulate colorectal cancer cell viability and migration by targeting PDCD4

Recent studies have revealed that microRNAs (miRs) are involved in the pathogenesis of colorectal cancer (CRC); however, the roles of miR-590-5p in CRC are not completely understood. Therefore, the present study investigated the expression of miR-590-5p and programmed cell death 4 (PDCD4) in CRC tissues and healthy adjacent tissues via reverse transcription-quantitative PCR. Furthermore, human CRC cells were cultured in vitro and transfected with miR-590-5p inhibitor. CRC cell viability, migration and invasion were evaluated by conducting MTT, wound healing and Transwell assays, respectively. Additionally, the relative expression of PDCD4 and phosphorylated-Smad2/3 was analyzed via western blotting. miR-590-5p was significantly upregulated and PDCD4 was significantly downregulated in CRC tissues compared with healthy adjacent tissues. Moreover, the results indicated that miR-590-5p knockdown inhibited cell viability and migration by altering the expression of PDCD4, transforming growth factor-β and phosphorylated-Smad2/3. PDCD4 was identified as a direct target of miR-590-5p. In conclusion, the results of the present study suggested that miR-590-5p may regulate CRC cell viability and migration, indicating that miR-590-5p may serve as a potential therapeutic target for CRC.

Forkhead box P3 promotes breast cancer cell apoptosis by regulating programmed cell death 4 expression

Forkhead box P3 (FOXP3), an X-linked tumor suppressor gene, plays an important role in breast cancer. However, the biological functions of FOXP3 in breast cancer apoptosis remain unclear. To investigate the underlying genes and networks regulated by FOXP3 in breast cancer, RNA sequencing was performed to compare FOXP3-overexpressing MDA-MB-231 cells and control MDA-MB-231 cells. Differentially expressed genes were identified, and functional enrichment analysis comparing the two groups was performed. The differentially expressed genes were mainly enriched in phagosomes, oxytocin, serotonergic synapses and the phospholipase D signaling pathway. Furthermore, gene set enrichment analysis revealed the enrichment of a gene signature associated with apoptosis in FOXP3-overexpressing MDA-MB-231 cells compared with wild-type cells. Further analysis showed that programmed cell death 4 (PDCD4), a key molecule involved in apoptosis, was overexpressed in FOXP3-MDA-MB-231 cells. Reverse transcription-quantitative PCR and western blotting showed that FOXP3 upregulated the expression of PDCD4 in breast cancer cells. Clinical sample analysis using a public database showed that the expression level of PDCD4 was associated with breast cancer clinical stages. Overall, the present study suggested that FOXP3 can promote the apoptosis of breast cancer cells by upregulating the expression of PDCD4, thus exerting a tumor suppressive function.

MicroRNA-21-5p targeting PDCD4 suppresses apoptosis via regulating the PI3K/AKT/FOXO1 signaling pathway in tongue squamous cell carcinoma

The aim of the present study was to analyze the role of microRNA (miRNA)-21-5p in tongue squamous cell carcinoma (TSCC), predict the target gene of miR-21-5p and provide novel strategies for gene therapy in TSCC treatment. The expression levels of miRNA-21-5p in TSCC tissues were analyzed using reverse transcription quantitative polymerase chain reaction, and the effects of miRNA-21-5p on cell proliferation, invasion and apoptosis and the expression levels of target protein PDCD4 in the Cal 27 and SCC9 cell lines were determined. PI3K/AKT/Forkhead Box O1 (FOXO1) pathway-associated protein expression levels were evaluated by western blot analysis. miRNA-21-5p was consistently upregulated in TSCC tissues compared with normal tissues. Inhibition of miR-21-5p inhibited cell proliferation and invasion, and promoted cell apoptosis. A luciferase reporter assay confirmed that PDCD4 was the target of miR-21-5p. Inhibition of miRNA21-5p suppressed the PI3K/Akt/FOXO1 signaling pathway. The results from the present study indicated that miR-21-5p-targeting PDCD4 suppresses apoptosis in human TSCC cell lines. This anti-apoptotic effect was achieved by regulating the PI3K/Akt/FOXO1 signaling pathway. These data represent the basis for a promising novel strategy for the treatment of TSCC.

[Long non-coding RNA XIST modulates cisplatin resistance by altering PDCD4 and Fas-Lexpressions in human nasopharyngeal carcinoma HNE1 cells in vitro]

OBJECTIVE

To explore the role of long non-coding RNA (lncRNA) X inactive specific transcript (XIST) in modulating cisplatin (DDP) resistance of human nasopharyngeal carcinoma cells and investigate the possible mechanism.

METHODS

Realtime PCR was performed to detect the expression of XIST in cisplatin-resistant human nasopharyngeal carcinoma cell line HNE1/DDP. The effects of up-regulation and down-regulation of XIST on DDP resistance, proliferation and apoptosis of HNE1/ DDP cells were assessed using MTT assay, EdU assay and flow cytometry. Western blotting was used to detect the changes in the expressions of programmed cell death 4 (PDCD4) and Fas ligand (Fas-L) proteins in the cells in response to up-regulation or down-regulation of XIST.

RESULTS

The expression of XIST was significantly up-regulated in HNE1/DDP cells in comparison with HNE1 cells (0.57±0.06 vs 0.1±0.02, P < 0.05). Down-regulation of XIST significantly decreased while up-regulation of XIST obviously increased DDP resistance of HNE1/DDP cells (P < 0.05). Down-regulation of XIST significantly reduced the proliferation (6.17 ± 1.93 vs 16.59 ± 4.86, P < 0.05) and enhanced apoptosis [(18.04 ± 4.72)% vs (4.22 ± 1.65)%, P < 0.05], while upregulating XIST enhanced the proliferation (25.40±7.21 vs 13.16±3.95, P < 0.05) and inhibited apoptosis [(2.82±0.88)% vs (6.46± 1.75)%, P < 0.05] in HNE1/DDP cells. Down-regulation of XIST significantly increased the protein expressions of PDCD4 and Fas-L (P < 0.05) in HNE1/DDP cells, and up-regulation of XIST resulted in reverse changes in PDCD4 and Fas-L expressions (P < 0.05).

CONCLUSIONS

XIST is up-regulated in HNE1/DDP cells, and down-regulation and up-regulation of XIST expression reduce and increase DDP resistance of the cells, respectively, possibly as a result of changes in the expressions of PDCD4 and Fas-L.

Clinical significance of decreased programmed cell death 4 expression in patients with giant cell tumors of the bone

Programmed cell death 4 (PDCD4) has been recognized as a novel tumor suppressor gene, which inhibits the activation and translation of activator protein (AP)-1. Dysregulated expression of PDCD4 is also involved in various human tumors and is linked to tumor progression and development. However, the function and clinical implication of PDCD4 in giant cell tumors of the bone (GCTBs) has not been previously investigated. In the present study, PDCD4 expression was determined in 83 samples of GCTBs at mRNA and protein levels by quantitative reverse transcription-polymerase chain reaction, western blotting and immunohistochemistry. The results demonstrated that PDCD4 mRNA expression was reduced in 63% of GCTB samples (17/27) and protein expression was decreased in 65% of samples (54/83), compared with adjacent non-tumor tissues. Furthermore, decreased expression of PDCD4 was significantly associated with certain clinicopathological characteristics, including the Campanacci grade and recurrence. A strong negative correlation was determined between PDCD4 expression and the Ki-67 positive rate in GCTBs (r=−0.6392; P<0.001). The results of the present study suggest that PDCD4 may serve a role in the malignant progression of human GCTBs and may be an important prediction factor for prognosis.

MiR-1260b inhibitor enhances the chemosensitivity of colorectal cancer cells to fluorouracil by targeting PDCD4/IGF1

Colorectal cancer (CRC) is the most common malignant tumor type and has become resistant to 5-fluorouracil (5-FU) in recent decades, which is one of the most popular therapies. Recently, microRNA (miRNA or miR) has been investigated as a potential therapeutic strategy for CRC. However, there has been little investigation of the underlying mechanism of the association between expression of miRNA and chemosensitivity. The present study aimed to investigate the effect of miR-1260b inhibitor on CRC cells, and their chemosensitivity to 5-FU, by treating them with the miR-1260b inhibitor. miR-1260b inhibitor was demonstrated to significantly promote the proliferation and invasion of the CRC cell line, HCT116, and to increase the apoptotic rate. Furthermore, it was validated that programmed cell death 4 (PDCD4) was a direct target of miR-1260b inhibitor in CRC with bioinformatics tools and a luciferase assay. Western blot analysis revealed that miR-1260b inhibitor could significantly decrease PDCD4 expression, and downregulate the expression of phosphorylated-Akt (p-Akt) and phosphorylated-extracellular-signal-regulated kinase (p-ERK). In conclusion, it was confirmed that the anti-tumor effect of the miR-1260b inhibitor was conducted by blocking the phosphorylated 3-kinase/Akt pathway as dysregulated protein expression induced by miR-1260b inhibitor was rescued by insulin-like growth factor. Notably, miR-1260b inhibitor could significantly enhanced the chemoresponse of HCT116 cells to 5-FU via reduced proliferation, increased apoptosis, and downregulation of PDCD4, p-Akt and p-ERK protein expression. In summary, the present study may provide a novel direction for future clinical therapy to enhance the chemosensitivity of tumor cells.

Linc00472 suppresses proliferation and promotes apoptosis through elevating PDCD4 expression by sponging miR-196a in colorectal cancer

Long intergenic non-coding RNA Linc00472 has been considered as a tumor suppressor in some cancers. However, the function and mechanism of Linc00472 in colorectal cancer has not been well elucidated. In this study, we found that Linc00472 was down-regulated in colorectal cancer tissues and cells. Elevated Linc00472 expression suppressed proliferation and induced apoptosis in colorectal cancer cells. Moreover, Linc00472 acted as a competing endogenous RNA (ceRNA) of miR-196a to release programmed cell death 4 (PDCD4). Furthermore, miR-196a overexpression or PDCD4 knockdown reversed Linc00472-mediated proliferation inhibition and apoptosis induction in colorectal cancer cells. Ectopic Linc00472 expression hindered tumor growth in vivo. Our study demonstrated that Linc00472 suppressed proliferation and induced apoptosis through up-regulating PDCD4 by decoying miR-196a, which may be an effective therapeutic target for colorectal cancer.

Expression of tumor suppressor programmed cell death 4 in endometrioid endometrial carcinomas and clinicopathological significance

Programmed cell death 4 (PDCD4), as a novel tumor suppressor, serves important roles in the pathogenesis of tumors. The expression of PDCD4 is downregulated or lost in various human tumors. However, the expression of PDCD4 in endometrial cancer and the clinicopathological significance remain unclear. The aim of the present study was to investigate the expression of PDCD4 in endometrioid endometrial carcinoma (EEC) and the association with clinicopathological parameters. The expression of PDCD4 in EEC tissues and control endometrium was detected by reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry. PDCD4 expression was also investigated in control endometrial glandular epithelial cells and the endometrial cancer KLE cell line by immunocytochemistry, and the association between PDCD4 expression and clinicopathological parameters of patients with EEC was analyzed. The results demonstrated that PDCD4-positive staining was mainly located in the cytoplasm of endometrial glandular epithelial cells and EEC cells. The staining index of PDCD4 in the proliferative phase was significantly increased compared with that in the secretory phase of control endometrium (P<0.001). There was significantly decreased PDCD4 expression in grade (G) 2/3 EEC tissues compared with the proliferative phase of control endometrium (P<0.001). PDCD4 expression was significantly associated with tumor grade. The PDCD4 levels in G1 EEC tissues were higher compared with the G2/3 EEC group (P<0.01). The results indicated that PDCD4 is associated with the histological grade of EEC, and that PDCD4 may be a valuable indicator of the degree of tumor malignancy in patients with EEC.

Defining the regulatory role of programmed cell death 4 in laryngeal squamous cell carcinoma

Programmed cell death 4 (PDCD4) is decreased in many different kinds of malignant tumors. EMT endows tumor cells invasive and metastatic properties. However, few studies have determined the role of PDCD4 in the regulation of EMT in the context of laryngeal carcinoma. We examined the relationship between PDCD4 and EMT-associated proteins E-cadherin and N-cadherin using laryngeal carcinoma tissues. Gene manipulation was used to define the regulatory capacity of PDCD4. We report that PDCD4 and E-cadherin/N-cadherin expression were significantly changed in the carcinoma tissues, and their expression was associated with pathological grade, metastatic state, and clinical stage. The suppression of PDCD4 (and consequently, E-cadherin) was concomitant with increased proliferation and G2-phase arrest, decreased apoptosis, and increased cell invasion. PDCD4 upregulation reversed the above-mentioned results. In nude mice, PDCD4 knockdown increased tumor growth and pathological features, confirming the tumorigenic role of PDCD4. Finally, PDCD4 silencing was associated with dysregulation of the carcinogenic Wnt-β-catenin and the STAT3-miR-21 signaling pathways. This study revealed a dynamic regulatory relationship between PDCD4 and critical factors for EMT, establishing a broad, functional role for PDCD4 in laryngeal carcinoma, which may be propagated by the STAT3-miR-21 pathway. These findings provide new information on an EMT-associated target that may lead to a novel therapy.

Prognostic significance of miR-21 and PDCD4 in patients with stage II esophageal carcinoma after surgical resection

Many studies have shown that randomized clinical trial with long-term follow-up found no improvement in stage II esophageal carcinoma (EC) patients receiving preoperative neoadjuvant chemoradiotherapy or chemotherapy treatment, this limitation underscored the urgent need for novel and reliable biomarkers for prognosis and prediction in stage II EC. miR-21 is frequently over-expressed while programmed cell death 4 (PDCD4) is often down-regulated in solid tumors. This study aimed to investigate the clinicopathological and prognostic significance of miR-21 and PDCD4 expression and to elucidate any correlation between miR-21 and PDCD4 expression in stage II EC patients. The expression level of miR-21 was up-regulated while the PDCD4 protein was down-regulated in stage II EC tissues compared with the adjacent non-cancerous tissues. Analyses of the clinicopathological parameters indicated that miR-21 expression was associated with differentiation grade, T stage, and N stage. PDCD4 protein expression was associated with T stage, N stage, and tumor size. The univariate linear regression analysis suggested a significant negative correlation between miR-21 and PDCD4 expression. The Kaplan-Meier curve showed that high miR-21 expression or low PDCD4 expression predicted poor progression-free survival (PFS) and overall survival (OS) of patients with stag II EC. In conclusion, both up-regulated miR-21 and down-regulated PDCD4 expression were associated with the aggressive progression and poor prognosis of stage II EC. miR-21 and PDCD4 might be potential biomarkers of tumor progression and indicators of prognosis of stag II EC.

Berberine regulates the microRNA-21-ITGΒ4-PDCD4 axis and inhibits colon cancer viability

Berberine is sourced from multiple medicinal herb resources and is easy to extract. With the advantages of low price, safety and convenience, berberine may have potential for wide clinical use. The present study aimed to investigate whether berberine inhibited the viability of colon cancer and whether it regulated the three-gene network microRNA (miR)-21-integrin β4 (ITGβ4)-programmed cell death 4 (PDCD4). It was demonstrated that berberine treatment suppressed colon cancer cell viability, and induced apoptosis and activated caspase-3 activity in the human colon carcinoma HCT116 cell line. Berberine inhibited miR-21 expression and promoted ITGβ4 and PDCD4 protein expression in the HCT116 cell line. Overexpression of miR-21 reduced the anti-cancer effects of berberine on cell viability, apoptosis rate and caspase-3 activity of the HCT116 cell line. However, it was revealed that the overexpression of miR-21 also suppressed ITGβ4 and PDCD4 protein expression in the HCT116 cell line. In conclusion, miR-21, ITGβ4 and PDCD4 are involved in the anti-cancer effects of berberine on cell viability and apoptosis in the HCT116 cell line.

Immunoexpression of programmed cell death 4 protein in normal oral mucosa, oral epithelial dysplasia and oral squamous cell carcinoma

Background:

Oral squamous cell carcinoma (OSCC) is the frequently reported cancer of the head and neck. Recent studies are being conducted to evaluate the role of potential markers for diagnosing the stages of development of OSCC from normal cells.

Aim:

The aim of this study is to evaluate and compare the immunoexpression of programmed cell death 4 (PDCD4) protein in normal oral mucosa, oral epithelial dysplasia (OED) and OSCC.

Materials and Methods:

Histologically diagnosed, formalin-fixed paraffin-embedded archived cases (n = 100) of normal mucosa (n = 10), OED (n = 60) and OSCC (n = 30) were analyzed immunohistochemically in the present retrospective study using monoclonal rabbit antihuman PDCD4. OED and squamous cell carcinoma were graded according to the World Health Organization and Broder's histological grading criteria, respectively. Clinical parameters and immunohistochemical results were analyzed by Fisher exact test using SPSS software. P <0.05 was indicative of significant differences.

Results:

PDCD4 expression was observed in the normal oral mucosa, OED and OSCC. The maximum expression was observed in the normal oral mucosa, which reduced significantly in OED and OSCC (P = 0.017). With the increase in the transformation from normal cells to cancer cells, a shift from nuclear to cytoplasmic staining was observed indicating predominant cytoplasmic localization of stain as a feature of altered cells.

Conclusion:

The present study delineates the molecular difference between the normal, dysplastic and carcinomatous cells; and points toward the role of PDCD4 localization in the proliferation of cells. This study thus highlights the need for further research with inclusion of long follow-up period and other pathological criteria such as inflammation and microenvironment, immune status of patient and tumor stage, which could aid in the development of prospective diagnostic options.

MiR-499-5p protects cardiomyocytes against ischaemic injury via anti-apoptosis by targeting PDCD4

Recent studies have reported that miRNAs might play critical roles in acute myocardial infarction (AMI). The objective of this study is to investigate the role of miR-499-5p in AMI and its potential molecular mechanisms. The expression level of MiR-499-5p was remarkably decreased in the infarcted myocardial tissues and in the cultured neonatal rat cardiomyocytes induced by hypoxia. Overexpression or knockdown of miR-499-5p decreased or increased the apoptotic rates of cultured cardiomyocytes in vitro. In addition, ectopic overexpression of miR-499-5p in the rat AMI models with agomir reduced the myocardial infarct size through decreasing the cardiomyocytes apoptosis in the infarcted area of the rat hearts. PDCD4 (programmed cell death 4) was verified as a direct target of miR-499-5p by luciferase report assay, and ectopic overexpression or inhibition of miR-499-5p could inhibit or increase the PDCD4 expression at both the mRNA and protein levels. Furthermore, we found that ectopic overexpression of PDCD4 without miR-499-5p binding sites reversed miR-499-5p-mediated cardiomyocytes apoptosis. Together, these findings revealed the role of miR-499-5p in protecting the cardiomyocytes against apoptosis induced by AMI via its direct target PDCD4, which providing evidence for the miR-499-5p/PDCD4 pathway as a potential therapeutic target for patients with AMI.

Programmed cell death 4 mechanism of action: The model to be updated?

Programmed cell death 4 (Pdcd4) is frequently suppressed in tumors of various origins and its suppression correlates with tumor progression. Pdcd4 inhibits cap-dependent translation from mRNAs with highly structured 5'-regions through interaction with the eukaryotic translation initiation factor 4A (eIF4A) helicase and a target transcript. Decrease in Pdcd4 protein is believed to provide a relief of otherwise suppressed eIF4A-dependent translation of proteins facilitating tumor progression. However, it remains unknown if lowered Pdcd4 levels in cells suffices to cause a relief in translation inhibition through appearance of the Pdcd4-free translation-competent eIF4A protein, or more complex and selective mechanisms are involved. Here we showed that eIF4A1, the eIF4A isoform involved in translation, significantly over-represents Pdcd4 both in cancerous and normal cells. This observation excludes the possibility that cytoplasmic Pdcd4 can efficiently exert its translation suppression function owing to excess of eIF4A, with Pdcd4-free eIF4A being in excess over Pdcd4-bound translation-incompetent eIF4A, thus leaving translation from Pdcd4 mRNA targets unaffected. This contradiction is resumed in the proposed model, which supposes initial complexing between Pdcd4 and its target mRNAs in the nucleus, with subsequent transport of translation-incompetent, Pdcd4-bound target mRNAs into the cytoplasm. Noteworthy, loss of nuclear Pdcd4 in cancer cells was reported to correlate with tumor progression, which supports the proposed model of Pdcd4 functioning.

Downregulation of PDCD4 by miR-21 suppresses tumor transformation and proliferation in a nude mouse renal cancer model

Programmed cell death 4 (PDCD4) is known to suppress neoplastic transformation, cell proliferation and metastasis, and to be downregulated by microRNA-21 (miR-21) in renal cell carcinoma (RCC) cell lines and tissues. The aim of the present study was to investigate the roles of and association between PDCD4 and miR-21 in a nude mouse renal cancer model. A total of 24 BALB/c male nude mice were randomly assigned into the following three groups: Negative control (NC; n=8), miR-21 inhibitor (n=8) and miR-21 mimic (n=8). Subsequently, renal cell adenocarcinoma 786-O cells were subcutaneously transplanted into the armpits of the mice, which were then injected daily with NC small interfering (si)RNA, precursor-miR-21 (mimic) or anti-miR-21 (inhibitor). Tumors were removed from the mice and weighed 16 days following 786-O cell transplantation. In addition, the expression of miR-21 and PDCD4 mRNA in cancer tissues was analyzed using reverse transcription-quantitative PCR. The expression of PDCD4 protein in cancer tissues was also examined using immunohistochemistry and western blotting. Furthermore, 786-O cells were transfected with PDCD4 siRNA or NC siRNA, and the effects of silencing PDCD4 on tumor cell growth, proliferation and invasion were investigated using soft agar colony formation, EdU cell proliferation assay and Transwell migration and invasion assays. Another 16 BALB/c male nude mice were randomly assigned into two groups as follows: NC (n=8) and PDCD4 siRNA (n=8). The 786-O cells were subcutaneously transplanted into the armpits of the mice, which were subsequently injected daily with NC siRNA or PDCD4 siRNA. The tumors were removed and weighed 16 days following transplantation. Compared with the NC group, tumor weight in the miR-21 mimic group was significantly increased. By contrast, tumor weight in the miR-21 inhibitor group was significantly decreased. Similar to the results observed in human renal cancer tissue and cell lines, miR-21 expression in the nude mouse renal cancer models was significantly upregulated in the miR-21 mimic group compared with the NC group, while it was significantly lower in the miR-21 inhibitor group. Furthermore, there was a significant reduction in PDCD4 protein levels in the miR-21 mimic group and a significant increase in the miR-21 inhibitor group compared with the NC, whereas PDCD4 mRNA expression was not significantly altered. In the EdU proliferation assay, the mean percentage of new cells that incorporated EdU was 28.6% in the NC siRNA group and significantly increased to 44.7% in PDCD4 siRNA transfected cells. In the soft agar colony formation assay, Transwell and migration and invasion assays, a significant increase in colony formation, migration and invasion capacity in PDCD4 siRNA-transfected cells was observed compared with the NC. Furthermore, compared with the NC group, tumor weight in the PDCD4 siRNA group was significantly increased. Similar to the results observed in human renal cancer tissue and cell lines, miR-21 promoted cancer cell hyperplasia and proliferation, and post-transcriptionally downregulated PDCD4 protein expression, in the nude mouse renal cancer model. The results of the present study and previous studies indicate that PDCD4 and miR-21 serve an important role in renal cancer. Thus, increasing PDCD4 expression or inhibiting miR-21 expression may constitute effective novel therapeutic strategies for the treatment of renal cancer.

MicroRNA-433 regulates apoptosis by targeting PDCD4 in human osteosarcoma cells

Osteosarcoma is the most common aggressive sarcoma of the bone in children and adolescents. It is characterized by a high level of genetic instability and recurrent DNA deletions and amplifications. microRNAs (miRNAs) play a key role in cancer initiation, progression and metastasis; however, the potential role of miRNAs in osteosarcoma remains largely unknown. In the present study, miR-433 was shown to be overexpressed in osteosarcoma tissues compared with normal human osteoblasts. Transfection of miR-433 mimics into osteosarcoma cell lines significantly decreased apoptosis by targeting programmed cell death 4, a tumor suppressor that is involved in apoptosis. In contrast, inhibition of miR-433 enhanced apoptosis. Furthermore, in vivo miR-433 overexpression inhibited the apoptosis of tumor cells and increased tumor growth. The results of the present study suggested that miR-433 is a potential molecular target for osteosarcoma therapy.

Reduction of miR-21 induces SK-N-SH cell apoptosis and inhibits proliferation via PTEN/PDCD4

MicroRNA (miR/miRNA)-21 is a well-known oncogenic miRNA that is overexpressed in various types of tumors. The tumor-suppressor genes programmed cell death 4 (PDCD4) and phosphatase tensin homologue (PTEN), are targets of miR-21, and are underexpressed in several types of cancer. However, the expression of miR-21 and its target genes in neuroblastoma (NB) remains unclear. In the present study, a miR-21 inhibitor oligonucleotide was transfected into the SK-N-SH cell line, and the expression of miR-21, PTEN and PDCD4 was detected through quantitative polymerase chain reaction analysis. Western blotting was used to examine levels of PTEN, PDCD4 and caspase-3 proteins. The expression of PTEN and PDCD4 in the SK-N-SH cell line transfected with the miR-21 inhibitor was significantly increased compared with untransfected SK-N-SH and negative control-transfected cells. Cell proliferation was inhibited and the apoptotic ratio was significantly increased in miR-21 inhibitor-transfected cells compared with untransfected SK-N-SH and negative control-transfected cells. Western blot analysis revealed a significant increase in caspase-3 expression compared with untransfected SK-N-SH and negative control-transfected cells. The results of the present study indicate that miR-21 may serve an oncogenic role in the cellular processes underlying NB development and thus may be a novel therapeutic target for the treatment of patients with NB.

Programmed cell death 4 and BCR-ABL fusion gene expression are negatively correlated in chronic myeloid leukemia

Programmed cell death 4 (PDCD4) is a tumor suppressor that inhibits carcinogenesis, tumor progression and invasion by preventing gene transcription and translation. Downregulation of PDCD4 expression has been identified in multiple types of human cancer, however, to date, the function of PDCD4 in leukemia has not been investigated. In the present study, PDCD4 mRNA and protein expression was investigated in 50 patients exhibiting various phases of chronic myeloid leukemia (CML) and 20 healthy individuals by reverse transcription-quantitative polymerase chain reaction and western blot analysis. PDCD4 expression and cell proliferation was also investigated following treatment with the tyrosine kinase inhibitor, imatinib, in K562 cells. The results demonstrated that PDCD4 mRNA and protein expression was decreased in all CML samples when compared with healthy controls, who expressed high levels of PDCD4 mRNA and protein. No significant differences in PDCD4 expression were identified between chronic phase, accelerated phase and blast phase CML patients. In addition, PDCD4 expression was negatively correlated with BCR-ABL gene expression (r=-0.6716; P<0.001). Furthermore, K562 cells treated with imatinib exhibited significantly enhanced PDCD4 expression. These results indicate that downregulation of PDCD4 expression may exhibit a critical function in the progression and malignant proliferation of human CML.

Expression and clinicopathological significance of microRNA-21 and programmed cell death 4 in malignant melanoma

OBJECTIVE

To measure levels of microRNA (miR)-21 and its target gene, programmed cell death 4 (PDCD4), in samples of human cutaneous malignant melanoma and normal non-malignant control skin.

METHODS

Relative levels of miR-21 and PDCD4 mRNA were measured using a quantitative real-time reverse transcription-polymerase chain reaction. Correlations between the levels of the two molecules and the clinicopathological characteristics of malignant melanoma were analysed.

RESULTS

A total of 67 cases of human cutaneous malignant melanoma were analysed and compared with 67 samples of normal nonmalignant control skin. Compared with normal skin samples, the relative level of miR-21 was significantly higher and the relative level of PDCD4 mRNA was significantly lower in the melanoma specimens. A significant negative correlation between PDCD4 mRNA and miR-21 was demonstrated in malignant melanoma (r = -0.602). Elevated miR-21 and reduced PDCD4 mRNA levels were both significantly correlated with increased tumour size, a higher Clark classification level and the presence of lymph node metastases in malignant melanoma.

CONCLUSIONS

These findings suggest that miR-21 and PDCD4 might be potential biomarkers for malignant melanoma and might provide treatment targets in the future.

Pdcd4 modulates markers of macrophage alternative activation and airway remodeling in antigen-induced pulmonary inflammation

Pdcd4 has been known as a tumor-suppressor gene initially and is up-regulated during apoptosis. Surprisingly, we found that Pdcd4 was differentially expressed in the lung from E3 rats with AIPI, an animal model for asthma, but the precise role of Pdcd4 in AIPI still remained to be defined. In the present study, we first evaluated the expression of Pdcd4 in lung from control and AIPI rats with RT-qPCR, Western blot, and immunohistochemistry. Then, we investigated the effects of intervention of Pdcd4 on markers of macrophage alternative activation and airway remodeling. Upon challenging E3 rats with OVA, Pdcd4 was up-regulated in lung tissue with AIPI. Immunohistochemistry results showed that alveolar macrophages and airway epithelia expressed Pdcd4 protein. Overexpression of Pdcd4 in the rat alveolar macrophage cell line, NR8383 cells, increased the mRNA expression of arginase-1 and TGF-β1, which are markers of macrophage alternative activation. In response to Pdcd4 RNAi in NR8383 cells, the mRNA expression of markers Fizz1, Ym1/2, arginase-1, and TGF-β1 was decreased significantly. In addition, Pdcd4 RNAi in AIPI rats led to a decrease of the mRNA expression of Fizz1, Ym1/2, arginase-1, and TGF-β1 in BALF cells. Finally, knockdown of Pdcd4 suppressed airway eosinophil infiltration, bronchus collagen deposition, and mucus production. Overall, these results suggest that Pdcd4 may be worthy of further investigation as a target for macrophage alternative activation and airway remodeling in allergic pulmonary inflammation.

Inhibition of microRNA-21 upregulates the expression of programmed cell death 4 and phosphatase tensin homologue in the A431 squamous cell carcinoma cell line

microRNA-21 (miRNA/miR-21) is a well-known oncogenic miRNA that is overexpressed in various carcinomas. The tumor suppressor genes, programmed cell death 4 (PDCD4) and phosphatase tensin homologue (PTEN), which target miR-21, are underexpressed in several types of cancer. However, the expression of miR-21 and its target genes, PDCD4 and PTEN, has not yet been reported in skin squamous cell carcinoma (SCC). In the present study, anti-miR-21 was transfected into the A431 cell line, and the expression of miR-21, PDCD4 and PTEN and the level of cell apoptosis were detected by quantitative polymerase chain reaction, immunocytochemistry and western blotting, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, respectively. The expression levels of PDCD4 and PTEN in the A431 cell line transfected with anti-miR-21 were significantly increased (P<0.05) and the apoptotic ratio was significantly increased (P<0.05). The data indicate that miR-21 may play an oncogenic role in the cellular processes of SCC and represent a novel target for effective therapies.

Diagnostic and prognostic value of circulating miR-21 for cancer: a systematic review and meta-analysis

BACKGROUND

MicroRNAs (miRNAs) have been reported to be aberrantly expressed in patients with cancer. Many studies have shown that circulating miRNAs could play potential roles as diagnostic and prognostic biomarkers of cancers. The aim of this meta-analysis is to summarize the role of circulating miR-21 as a biomarker in patients with a variety of carcinomas.

MATERIAL AND METHODS

Eligible studies were identified and assessed for quality through multiple search strategies. For diagnostic meta-analysis, the sensitivity, specificity, and other measures of miR-21 in the diagnosis of cancer were pooled using bivariate random-effects approach models. For prognostic meta-analysis, pooled hazard ratios (HRs) of circulating miR-21 for survival were calculated.

RESULTS

A total of 36 studies dealing with various carcinomas were included for the systemic review. Among them, 23 studies were finally enrolled in the global meta-analysis (17 studies for diagnosis and 6 studies for prognosis). For diagnostic meta-analysis, the overall pooled results for sensitivity, specificity, positive likelihood ratio (LRP), negative likelihood ratios (LRN) and diagnostic odds ratio (DOR) were 75.7% (95% CI: 67.1%-82.6%), 79.3% (95% CI: 74.2%-83.5%), 3.65 (95% CI: 2.83-4.70), 0.31 (95% CI: 0.22-0.43), and 11.88 (95% CI: 6.99-20.19), respectively. For prognostic meta-analysis, the pooled HR of higher miR-21 expression in circulation was 2.37 (95% CI: 1.83-3.06, P<0.001), which could significantly predict poorer survival in general carcinomas. Importantly, subgroup analysis suggested that higher expression of miR-21 correlated with worse overall survival (OS) significantly in carcinomas of digestion system (HR, 5.77 [95% CI: 2.65-12.52]).

CONCLUSIONS

Our findings suggest that circulating miR-21 may not suitable to be a diagnostic biomarker, but it has a prognostic value in patients with cancer.

Regulation of muscle protein synthesis and the effects of catabolic states

Protein synthesis and degradation are dynamically regulated processes that act in concert to control the accretion or loss of muscle mass. The present article focuses on the mechanisms involved in the impairment of protein synthesis that are associated with skeletal muscle atrophy. The vast majority of mechanisms known to regulate protein synthesis involve modulation of the initiation phase of mRNA translation, which comprises a series of reactions that result in the binding of initiator methionyl-tRNAi and mRNA to the 40S ribosomal subunit. The function of the proteins involved in both events has been shown to be repressed under atrophic conditions such as sepsis, cachexia, chronic kidney disease, sarcopenia, and disuse atrophy. The basis for the inhibition of protein synthesis under such conditions is likely to be multifactorial and includes insulin/insulin-like growth factor 1 resistance, pro-inflammatory cytokine expression, malnutrition, corticosteroids, and/or physical inactivity. The present article provides an overview of the existing literature regarding mechanisms and signaling pathways involved in the regulation of mRNA translation as they apply to skeletal muscle wasting, as well as the efficacy of potential clinical interventions such as nutrition and exercise in the maintenance of skeletal muscle protein synthesis under atrophic conditions. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.

Myocardial and circulating levels of microRNA-21 reflect left ventricular fibrosis in aortic stenosis patients

BACKGROUND

Various human cardiovascular pathophysiological conditions associate aberrant expression of microRNAs (miRNAs) and circulating miRNAs are emerging as promising biomarkers. In mice, myocardial miR-21 overexpression is related to cardiac fibrosis elicited by pressure overload. This study was designed to determine the role of myocardial and plasmatic miR-21 in the maladaptive remodeling of the extracellular matrix induced by pressure overload in aortic stenosis (AS) patients and the clinical value of miR-21 as a biomarker for pathological myocardial fibrosis.

METHODS

In left ventricular biopsies from 75 AS patients and 32 surgical controls, we quantified the myocardial transcript levels of miR-21, miR-21-targets and ECM- and TGF-β-signaling-related elements. miR-21 plasma levels were determined in 25 healthy volunteers and in AS patients. In situ hybridization of miR-21 was performed in myocardial sections.

RESULTS

The myocardial and plasma levels of miR-21 were significantly higher in the AS patients compared with the controls and correlated directly with the echocardiographic mean transvalvular gradients. miR-21 overexpression was confined to interstitial cells and absent in cardiomyocytes. Using bootstrap validated multiple linear regression, the variance in myocardial collagen expression was predicted by myocardial miR-21 (70% of collagen variance) or plasma miR-21 (52% of collagen variance), together with the miR-21 targets RECK and PDCD4, and effectors of TGF-ß signaling.

CONCLUSIONS

Our results support the role of miR-21 as a regulator of the fibrotic process that occurs in response to pressure overload in AS patients and underscore the value of circulating miR-21 as a biomarker for myocardial fibrosis.

Programmed cell death 4 (Pdcd4) expression in colorectal adenocarcinoma: Association with clinical stage

The aim of this study was to examine the role of Programmed cell death 4 (Pdcd4) in colorectal adenocarcinoma (CRA). Pdcd4 expression was observed in both the nucleus and cytoplasm in colorectal adenocarcinoma, whereas Pdcd4 was expressed in the nucleus in normal colonic epithelial cells. Loss or weak expression of Pdcd4 was identified in 44 cases (40.7%) of cancer cells. Pdcd4 expression was associated with an increase in the nodal and clinical stage (p=0.022 and p=0.016, respectively). Nuclear staining was identified in 66 cases (61.15%), with no correlation with clinicopathological factors. Conversely, cytoplasmic staining for Pdcd4 was observed in 45 cases (41.7%), and increased according to nodal and clinical stage (p=0.011 and p=0.009, respectively), indicating that aberrant Pdcd4 expression leads to tumor progression. However, Pdcd4 expression was not correlated to disease-free survival time. This study demonstrated that during the tumorigenesis of CRA, loss of nuclear Pdcd4 expression occurs, and during tumor progression, aberrant cytoplasmic expression is present, suggesting a higher clinical stage. Although loss of Pdcd4 was not significantly correlated with survival time, as the prognosis of colorectal cancer varies depending on clinical stage including invasion depth, nodal status and metastatic status, cytoplasmic Pdcd4 expression may be a favorable prognostic marker in CRA.