Busulfan inhibits growth of human osteosarcoma through miR-200 family microRNAs in vitro and in vivo

Regulation of activating protein-4-associated metastases of non-small cell lung cancer cells by miR-144

Activating protein-4 (AP4) has been recently shown to regulate the cancer metastases in some cancers including non-small cell lung cancer (NSCLC). Specifically, AP4 regulates mTor/p21 and transforming growth factor β (TGFβ) receptor signaling pathway to increase an epithelial-mesenchymal transition process to augment cell invasiveness. Nevertheless, how AP4 is regulated in NSCLC has not been studied. Here, we showed that in the specimens from the NSCLC patients, the levels of miR-144 were significantly decreased and the levels of AP4 were significantly increased, compared to the paired non-tumor lung tissue. The levels of miR-144 and AP4 inversely correlated in patients' specimens. Bioinformatics analyses revealed that miR-144 targeted the 3'-UTR of AP4 mRNA to inhibit its translation, confirmed by luciferase-reporter assay. Moreover, miR-144 overexpression inhibited AP4-mediated cell invasiveness, while miR-144 depletion increased AP4-mediated cell invasiveness in NSCLC cells. Together, our data suggest that miR-144 suppression may be the cause of the increased levels of AP4, as well as the augmented cancer metastases, in NSCLC.

MiR-200 suppresses metastases of colorectal cancer through ZEB1

Poor prognosis of some colorectal cancer (CRC) cases largely results from early metastases of CRC to the distal organs. Thus, suppression of the invasion of CRC appears to be crucial therapy. Since microRNAs (miRNAs) play critical roles in the regulation of cancer metastases, identification of the involved miRNAs may provide novel therapeutic targets for CRC treatment. Here, we showed that the levels of miR-200 were significantly decreased and the levels of ZEB1 were significantly increased in the CRC specimens from patients, compared to the paired non-tumor tissue. Moreover, the levels of miR-200 and ZEB1 are inversely correlated. Bioinformatics analyses showed that miR-200 targeted the 3'-UTR of ZEB1 mRNA to inhibit its translation, which was confirmed by luciferase reporter assay. Moreover, miR-200 overexpression inhibited ZEB1-mediated cell invasiveness, while miR-200 depletion increased ZEB1-mediated cell invasiveness in CRC cells. Together, our data suggest that miR-200 suppression in CRC cells may promote ZEB1-mediated cancer metastasis. Our work thus highlights a novel molecular regulatory machinery that regulates metastases of CRC.

MiR-153 regulates metastases of gastric cancer through Snail

MicroRNAs (miRNAs) play critical roles in tumorigenesis and cancer metastases of gastric carcinoma (GC). Recently, miR-153 was reported as a tumor suppressor miRNA silenced in GC, whereas the underlying mechanisms are much lacking. Here, we reported that miR-153 levels were significantly decreased and Snail levels were significantly increased in GC specimens, compared to paired adjacent non-tumor gastric tissue. Moreover, the levels of miR-153 and Snail were inversely correlated. Bioinformatics analyses and luciferase reporter assay showed that miR-153 targeted the 3'-untranslated region (3'-UTR) of Snail messenger RNA (mRNA) to inhibit its translation. Overexpression of miR-153 inhibited Snail-mediated cell invasiveness, while depletion of miR-153 increased Snail-mediated cell invasiveness in both Transwell cell migration assay and scratch wound healing assay. Thus, our data suggest that miR-153 suppression in GC promotes Snail-mediated cancer metastases. Re-establishment of miR-153 levels in GC may suppress cancer invasion.

Fluorouracil induces autophagy-related gastric carcinoma cell death through Beclin-1 upregulation by miR-30 suppression

The molecular mechanisms underlying the anti-cancer effects of chemotherapy drugs are not completely understood. Here, we studied the effects of fluorouracil (5-FU) on gastric carcinoma (GC) cells. We found that 5-FU dose-dependently inhibited the growth of GC cells, in either a cell counting kit-8 (CCK-8) assay or a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, autophagy-associated protein 6 (ATG6) or Beclin-1 was dose-dependently activated by 5-FU in GC cells. Further, microRNA (miR)-30 was found to be regulated by 5-FU, and bioinformatics analysis showed that miR-30 targeted the 3'-UTR of Beclin-1 to inhibit its translation. Together, these data suggest that 5-FU may suppress miR-30 to upregulate Beclin-1 to induce autophagic cell death and cell proliferation arrest in GC cells.

miR-203 suppression in gastric carcinoma promotes Slug-mediated cancer metastasis

MicroRNAs (miRNAs) play critical roles in tumorigenesis and cancer metastasis. Recently, miR-203 was reported as a tumor suppressor microRNA silenced in different malignancies including hepatocellular carcinoma, prostate cancer, oral cancer, breast cancer, and hematopoietic malignancy, whereas its role in the carcinogenesis of gastric carcinoma (GC) has not been evaluated. Here, we analyzed the levels of miR-203 and Slug in the GC specimen and studied their correlation. We analyzed the binding of miR-203 to the 3'-UTR of Slug messenger RNA (mRNA) and its effects on Slug translation by bioinformatics analysis and by luciferase-reporter assay, respectively. We modified miR-203 levels in GC cells and studied their effects on the cell invasiveness in transwell cell migration assay. We found that in GC, miR-203 levels were significantly decreased and Slug levels were significantly increased. miR-203 and Slug inversely correlated in patients' specimen. Bioinformatic analysis predicted that miR-203 may target the 3'-UTR of Slug mRNA to inhibit its translation, which was confirmed by luciferase-reporter assay. Overexpression of miR-203 inhibited Slug and cell invasiveness, while depletion of miR-203 increased Slug and cell invasiveness. These data suggest that miR-203 suppression in GC promotes Slug-mediated cancer metastasis.

MiR-449c inhibits gastric carcinoma growth

AIMS

Gastric carcinoma (GC) is among the leading causes of cancer-related deaths in China. Growing evidence indicates that dysregulation of miRNAs contributes to GC development. Although it has been shown that miR-449c acts as a tumor suppressor in lung cancer, the role of miR-449c in GC remains unclear.

MAIN METHODS

Here, we analyzed miR-449c levels in GC tissues and cell lines by RT-qPCR. We also overexpressed and inhibited miR-449c by transfecting miRNA mimics and antisense oligonucleotides (ASO), respectively. Cell growth was analyzed by MTT assay, and cell apoptosis was evaluated by FACS analysis. MiR-449c target genes were predicted using bioinformatics algorithms and confirmed by a dual luciferase reporter assay.

KEY FINDINGS

We detected lower miR-449c levels in GC tissues; the low miR-449c levels correlated with low survival rate. Overexpression of miR-449c inhibited cell growth and promoted apoptosis, while depletion of miR-449c increased cell growth and suppressed apoptosis. Moreover, the 3' UTR of MET, an oncogene that activates tumor cell growth, appeared to be targeted by miR-449c.

SIGNIFICANCE

Together, we showed that the reduced miR-449c levels in GC tissues promote GC growth, which possibly contributes to the low survival rate of GC patients. Mechanistically, miR-449c may target MET to suppress GC cell growth.

Impairment of growth of gastric carcinoma by miR-133-mediated Her-2 inhibition

Gastric carcinoma (GC) is a leading cause of cancer-related death in China. Dysregulation of microRNAs (miRNAs) has been shown to contribute to the development of GC, whereas the role of miR-133 in GC is unknown. Here, we analyzed the levels of miR-133 in GC tissues by reverse and quantitative transcription polymerase chain reaction (RT-qPCR). We overexpressed or inhibited miR-133 in GC cells. Cell growth was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and cell apoptosis was evaluated by fluorescence-activated cell sorting (FACS) analysis. Targeted genes were predicted by a bioinformatics algorithm and confirmed by a dual-luciferase reporter assay. We detected lower miR-133 levels in GC tissues compared with normal gastric tissue. Moreover, the low miR-133 levels were correlated with low survival rate. Overexpression of miR-133 inhibited cell growth and promoted apoptosis, while depletion of miR-133 increased cell growth and suppressed apoptosis. Moreover, the 3'-untranslated region (3'UTR) of Her-2, the epidermal growth factor receptor (EGFR) that transduces cell growth signals, appeared to be targeted by miR-133. Together, these data suggest that reduced miR-133 levels in GC tissues promote GC growth, which possibly contributes to a low survival rate of GC patients. MiR-133 may target Her-2 to suppress GC cell growth.

Expression of serum miR-200a, miR-200b, and miR-200c as candidate biomarkers in epithelial ovarian cancer and their association with clinicopathological features

BACKGROUND

MicroRNAs (miRs) have been implicated in the etiology of various human cancers. The aim of this study was to investigate the association of the expression of three members--miR 200a, miR 200b, and miR 200c belonging to the miR-200 family with clinicopathological characteristics and their impact on the progression of epithelial ovarian cancer (EOC).

MATERIALS AND METHODS

Total RNA from serum was isolated by Trizol method, polyadenylated, and reverse transcribed into cDNA. Expression levels of miR-200a, miR-200b, and miR-200c were detected by using miRNA qRT-PCR. We measured miR expression in 70 serum samples of EOC patients with matched controls using U6 snRNA as a reference. Levels of miR expression was compared with distinct clinicopathological features.

RESULTS

Expression of miR-200a was found to be greater than six-fold (p = 0.01), miR-200b and miR-200c greater than three-fold (p = 0.01) in comparison with matched normal controls. Association of miRNA expression with clinicopathological factors and progression was statistically evaluated. The expression levels of miR-200a and miR-200c were found to be significantly associated with disease progression (p = 0.04 and p < 0.001, respectively). miR-200a overexpression was found be associated with tumor histology and stage. Patients with lymph node metastasis showed significant elevation of miR-200c (p = 0.006). The AUC in ROC curve also indicated that serum levels of miR-200a and miR-200c might be worthwhile as a diagnostic tool in the near future.

CONCLUSION

Our findings suggest that miR-200a, miR-200b, and miR-200c overexpressions are associated with the aggressive tumor progression and be recognized as reliable markers to predict the prognosis and survival in EOC patients.

Regulation of MET-mediated proliferation of thyroid carcinoma cells by miR-449b

Thyroid carcinoma (TC) is a lethal cancer worldwide, whereas its carcinogenesis is not fully understood. Although growing evidence has demonstrated that dysregulation of microRNAs (miRNAs) contributes to the development of various cancers, the role of miRNAs in the pathogenesis of TC is poorly characterized. Here, we analyzed the levels of miR-449b in TC tissues and detected significantly lower miR-449b levels in TC tissues. Moreover, the low miR-449b levels were associated with poor survival. We then overexpressed miR-449b by miRNA mimic transfection and inhibited miR-449b by miRNA antisense transfection. Cell growth was analyzed by CCK-8 assay and MTT assay, and apoptosis and cell proliferation were analyzed by flow cytometry. Overexpression of miR-449b significantly inhibited cell growth, while depletion of miR-449b increased cell growth. Moreover, the effects of miR-449b on cell growth were through modulation of cell proliferation rather than through modulation of cell apoptosis. Targeted genes were predicted by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay, showing that miR-449b binds to the 3'-UTR of MET (hepatocyte growth factor receptor) mRNA, to inhibit its expression in TC cells. MET levels were regulated by miR-449b in TT cells. Together, we show that reduced miR-449b levels in TT tissues may promote TC growth, through MET-mediated cell proliferation.

Promyelocytic leukemia protein enhances apoptosis of gastric cancer cells through Yes-associated protein

It has been shown that Yes-associated protein (YAP) acts as a transcriptional co-activator to regulate p73-dependent apoptosis in response to DNA damage in some cell types, and promyelocytic leukemia (PML) protein is involved in the regulation loop through stabilization of YAP through sumoylation. Although YAP has been shown to be significantly upregulated in gastric cancer, whether the YAP/PML/p73 regulation loop also functions in gastric cancer is unknown. Here, we show significantly higher levels of YAP and significantly lower levels of PML in the gastric cancer specimen. Overexpression of YAP in gastric cancer cells significantly increased cell growth, but did not affect apoptosis. However, overexpression of PML in gastric cancer cells significantly increased cell apoptosis, resulting in decreases in cell growth, which seemed to require the presence of YAP. The effect of PML on apoptosis appeared to be conducted through p73-mediated modulation of apoptosis-associated genes, Bcl-2, Bak, and caspase9. Thus, our study suggests the presence of a YAP/PML/p73 regulatory loop in gastric cancer, and highlights PML as a promising tumor suppressor in gastric cancer through YAP-coordinated cancer cell apoptosis.

SEMA4B inhibits growth of non-small cell lung cancer in vitro and in vivo

We have recently shown that Semaphorin 4B (SEMA4B) inhibits the invasion of non-small cell lung cancer (NSCLC) through PI3K-dependent suppression of MMP9 activation. In the current study, we evaluated whether SEMA4B may also affect the growth of NSCLC. We thus used two human NSCLC lines, A549 and Calu-3, to examine our hypothesis. We found that overexpression of SEMA4B significantly decreased NSCLC cell growth, while SEMA4B inhibition significantly increased NSCLC cell growth, both in vitro and in vivo in an implanted NSCLC model. Adaptation of SEMA4B in NSCLC cells did not alter cell apoptosis, but changed the cell proliferation. Further analyses show that SEMA4B may induce FoxO1 nuclear retention through suppressing PI3K/Akt signaling pathway, which subsequently inhibited cell growth through the direct nuclear target of FoxO1, p21. Our study thus demonstrate a role of SEMA4B in suppressing NSCLC growth, besides its role in inhibiting cell metastasis, and highlights SEMA4B as a promising therapeutic target for NSCLC.

Depletion of ALX1 causes inhibition of migration and induction of apoptosis in human osteosarcoma

Osteosarcoma is the most common primary malignant tumor in children and young adults, and the molecular regulation of the invasion of osteosarcoma (OS) remains unknown. In this study, we found that increased expression of ALX1 was associated with the progression of osteosarcoma and that ALX1 protein levels were significantly elevated in matched distant metastases. High ALX1 levels also predict shorter overall survival of osteosarcoma patients. We investigated the therapeutic potential of targeting ALX1 expression using the technique of RNA silencing via short hairpin RNA (shRNA). Synthetic shRNA duplexes against ALX1 were introduced to downregulate the expression of ALX1 in a highly malignant osteosarcoma cell line, U2OS. The results obtained indicated that shRNA targeting of ALX1 could lead to an efficient and specific inhibition of endogenous ALX1 activity. Furthermore, we found that depletion of ALX1 caused a dramatic cell cycle arrest, followed by massive apoptotic cell death, and eventually resulted in a significant decrease in migration and invasion of the osteosarcoma cell line studied.

MicroRNAs in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor with high morbidity that principally emerges in children and adolescents. Presently, the prognosis of OS patients remains poor due to resistance to chemotherapy, highlighting the need for new therapeutic approaches. MicroRNAs (miRNAs), a class of small noncoding RNA molecules, can negatively modulate protein expression at the post-transcriptional level. miRNAs regulate a variety of normal physiologic processes and are involved in tumorigenesis and development of multiple malignancies, including OS. Some miRNAs are differentially expressed in OS tissues, cell lines and serum, and have been shown to correlate with the malignant phenotype and prognosis. These altered miRNAs function as oncogenes or tumor suppressor genes in this process. Moreover, restoration of miRNA expression has shown promise for the treatment of OS. Here, we describe miRNA biochemistry with a focus on expression profile, role and therapeutic potential in OS. A better understanding will facilitate the identification and characterization of novel biomarkers and development of miRNA-targeted therapies.

Androgen receptor signaling regulates growth of glioblastoma multiforme in men

Although glioblastoma multiforme (GBM) is the most malignant primary human brain cancer with surprisingly high incidence rate in adult men than in women, the exact mechanism underlying this pronounced epidemiology is unclear. Here, we showed significant upregulated androgen receptor (AR) expression in the GBM tissue compared to the periphery normal brain tissue in patients. An expression of AR was further detected in all eight examined human GBM cell lines. To figure out whether AR signaling may play a role in GBM, we used high AR-expressing U87-MG GBM line for further study. We found that activation of transforming growth factor β (TGFβ) receptor signaling by TGFβ1 in GBM significantly inhibited cell growth and increased apoptosis. Moreover, application of active AR ligand 5α-dihydrotestosterone (DHT) significantly decreased the effect of TGFβ1 on GBM growth and apoptosis, suggesting that AR signaling pathway may contradict the effect of TGFβ receptor signaling in GBM. However, neither total protein nor the phosphorylated protein of SMAD3, a major TGFβ receptor signaling downstream effector in GBM, was affected by DHT, suggesting that AR activation may not affect the SMAD3 protein production or phosphorylation of TGFβ receptor and SMAD3. Finally, immunoprecipitation followed by immunoblot confirmed binding of pAR to pSMAD3, which may prevent the DNA binding of pSMAD3 and subsequently prevent its effect on cell growth in GBM. Taken together, our study suggests that AR signaling may promote tumorigenesis of GBM in adult men by inhibiting TGFβ receptor signaling.

MiR-143 inhibits EGFR-signaling-dependent osteosarcoma invasion

The molecular regulation of the invasion of osteosarcoma (OS) remains elusive. Here, we reported significant lower level of miR-143 and significant levels of phosphorylated EGFR and MMP9 in the resected OS from the patients, compared to the adjacent normal tissue. Moreover, strong correlation was detected among these three factors. We thus hypothesized existence of a causal link, which prompted us to use two human OS cell lines to study the interaction of miR-143, MMP9, and activation of EGFR signaling. We found that EGF-induced EGFR phosphorylation in both lines activated MMP9, and consequently cancer invasiveness. Both an inhibitor for EGFR phosphorylation and an inhibitor for ERK1/2 phosphorylation significantly inhibited the EGF-induced activation of MMP9. Moreover, miR-143 levels did not alter by EGF-induced EGFR phosphorylation, while overexpression of miR-143 antagonized EGF-induced MMP9 activation without affecting EGFR phosphorylation. Taken together, our data suggest that miR-143 inhibits EGFR signaling through its downstream ERK/MAPK signaling cascades to control MMP9 expression in OS. Thus, miR-143, EGFR, and MMP9 are therapeutic targets for inhibiting OS invasion.