MALAT1: a potential biomarker in cancer.

PURPOSE: The research of long non-coding RNAs (lncRNAs) has become a new passion with the discovery of abundant new lncRNAs and extensive investigation of their roles in various diseases, especially in cancers. Metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) emerges as a hotspot, which has been reported to be involved in dysregulation of cell signaling and closely correlated with cancer development, progression, and response to therapy. This review is a brief update of the current knowledge related to the role of MALAT1 in cancer-associated molecular pathways and pathophysiology and possible determinants for MALAT1 to function as a biomarker, aiming to stimulate the basic investigation of lncRNA MALAT1 as well as its translation to clinical applications. METHODS: We have selected vast literature from electronic databases including studies associated with its clinical significance and the pivotal functions in cancer processes such as cell proliferation, apoptosis, metastasis, immunity, angiogenesis, and drug resistance. RESULTS: Studies have shown that aberrant expression of MALAT1 is related to cancer pathophysiology with the potential to be translated clinically and MALAT1 can regulate cancer processes by interacting with molecules, such as proteins, RNAs and DNAs, and further altering different signal pathways. CONCLUSION: MALAT1 lncRNA promises to be a potential biomarker for cancer diagnosis as well as prognosis. Additionally, it might be a therapeutic target for human cancers.

Emerging role of long non-coding RNAs in cisplatin resistance.

Cisplatin (CDDP) is one of the most commonly used chemotherapy drugs for the treatment of various cancers. Although platinum-based therapies are highly efficacious against rapidly proliferating malignant tumors, the development of CDDP resistance results in significant relapse as well as decreased overall survival rates, which is a significant obstacle in CDDP-based cancer therapy. Long non-coding RNAs (lncRNAs) are involved in cancer development and progression by the regulation of processes related to chromatin remodeling, transcription, and posttranscriptional processing. Emerging evidence has recently highlighted the roles of lncRNAs in the development of CDDP resistance. In this review, we discuss the roles and mechanisms of lncRNAs in CDDP chemoresistance, including changes in cellular uptake or efflux of a drug, intracellular detoxification, DNA repair, apoptosis, autophagy, cell stemness, and the related signaling pathways, aiming to provide potential lncRNA-targeted strategies for overcoming drug resistance in cancer therapy.

Bioinformatics-based identification of miR-542-5p as a predictive biomarker in breast cancer therapy.

BACKGROUND: Tamoxifen is the first-line hormone therapy for estrogen receptor alpha positive (ERα+) breast cancer. However, about 40% of patients with ERα + breast cancer who receive tamoxifen therapy eventually develop resistance resulting in a poor prognosis. The aim of this study was to mine available data sets in the Gene Expression Omnibus (GEO) database, including in vitro (cell lines) and in vivo (tissue samples), and to identify all miRNAs associated with tamoxifen resistance (TamR) in breast cancer. Secondly, this study aimed to predict the key gene regulatory networks of newly found TamR-related miRNAs and evaluate the potential role of the miRNAs and targets as potential prognosis biomarkers for breast cancer patients. RESULT: Microarray data sets from two different studies were used from the GEO database: 1. GSE66607: miRNA of MCF-7 TamR cells; 2. GSE37405: TamR tissues. Differentially expressed microRNAs (miRNAs) were identified in both data sets and 5 differentially expressed miRNAs were found to overlap between the two data sets. Profiles of GSE37405 and data from the Kaplan-Meier Plotter Database (KMPD) along with Gene Expression Profiling Interactive Analysis (GEPIA) were used to reveal the relationship between these 5 miRNAs and overall survival. The results showed that has-miR-542-5p was the only miRNA associated with overall survival of ERα + breast cancer patients who received adjuvant tamoxifen. Targets of has-miR-542-5p were predicted by miRanda and TargetScan, and the mRNA expression of the three 3 target gene, Tyrosine 3-Monooxygenase/Tryptophan 5-Monooxygenase Activation Protein Beta (YWHAB), Lymphocyte Antigen 9 (LY9), and Secreted Frizzled Related Protein 1 (SFRP1) were associated with overall survival in 2 different databases. Copy-number alterations (CNAs) of SFRP1 confer survival disadvantage to breast cancer patients and alter the mRNA expression of SFRP1 in cBioPortal database. CONCLUSION: This study indicates that miRNA has-miR-542-5p is associated with TamR and can predict prognosis of breast cancer patients. Furthermore, has-miR-542-5p may be acting through a mechanism involving the target genes YWHAB, LY9, and SFRP1. Overall, has-miR-542-5p is a predictive biomarker and potential target for therapy of breast cancer patients.

LncRNA H19 is a major mediator of doxorubicin chemoresistance in breast cancer cells through a cullin4A-MDR1 pathway.

Development of chemoresistance is a persistent problem during cancer treatment. Long non-coding RNAs (LncRNAs) are currently emerging as an integral functional component of the human genome and as critical regulators of cancer development and progression. In the present study, we investigated the role and molecular mechanism of H19 lncRNA in chemoresistance development by using doxorubicin (Dox) resistance in breast cancer cells as a model system. H19 lncRNA expression was significantly increased in anthracycline-treated and Dox-resistant MCF-7 breast cancer cells. This H19 overexpression was contributed to cancer cell resistance to anthracyclines and paclitaxel as knockdown of H19 lncRNA by a specific H19 shRNA in Dox-resistant cells significantly improved the cell sensitivity to anthracyclines and paclitaxel. Furthermore, gene expression profiling analysis revealed that a total of 192 genes were associated with H19-mediated Dox resistance. These genes were enriched in multiple KEGG pathways that are related to chemoresistance. Using genetic and pharmacological approaches, we demonstrated that MDR1 and MRP4 were major effectors of H19-regulated Dox resistance in breast cancer cells as MDR1 and MRP4 expression was markedly elevated in Dox-resistant cells while dramatically reduced when H19 was knocked down. Moreover, we found that CUL4A, an ubiquitin ligase component, was a critical factor bridging H19 lncRNA to MDR1 expression, and a high tumor CUL4A expression was associated with low survival in breast cancer patients treated with chemotherapy. These data suggest that H19 lncRNA plays a leading role in breast cancer chemoresistance, mediated mainly through a H19-CUL4A-ABCB1/MDR1 pathway.

Ontogeny, aging, and gender-related changes in hepatic multidrug resistant protein genes in rats.

Multidrug resistance proteins (Mrps) are efflux transporters playing important roles in endogenous substances and xenobiotics transport out of the liver. Children, elderly, gender and physio-pathological conditions could influence their expression and result in changes in drug disposition. AIM: This study was aimed to examine the development-, aging-, and sex-dependent changes in Mrp1-4 and ATP-binding cassette sub-family G member 2 (Abcg2) gene expressions in livers of rats. MAIN METHODS: The livers from male and female SD rats at development (-2, 1,7,14,21,28,35, and 60d) and aging (28, 60, 180 and 540d) were collected and total RNA was isolated, purified and subjected to real-time RT-PCR analysis. KEY FINDINGS: Results showed that expression of Mrp1 was low, while Abcg2 and Mrp2 were the high in the liver. Mrp1 expression decreased with maturity but remained constant to 540d, while Mrp3 and 4 increased with liver development, reached the peak with maturity at 35-60days of age, and slightly reduced with aging. Mrp2 and Abcg2 were high at 7days of age and maintained at relative high levels till maturity, while Abcg2 was reduced during aging. Females had higher Mrp3 and Abcg2 mRNA expression than male rats, while male rats had higher Mrp2 and Mrp4 mRNA expression. SIGNIFICANCE: The expression of hepatic Mrp1-4 and Abcg2 mRNA during development, aging in male and female rats was characterized, which could be fundamental to our understanding of age- and sex-associated variations in drug disposition in children, elderly, and women.

H19 lncRNA mediates 17ß-estradiol-induced cell proliferation in MCF-7 breast cancer cells.

Estrogen plays a critical role in breast cancer development and progression. However, the mechanism involved in the promotion of breast cancer development and progression by estrogen remains unclear although it has been intensively studied. In the present study, we investigated the estrogen inducibility and functional significance of H19 lncRNA in breast cancer cells and tumor tissues. The screening of 83 disease-related long non-coding RNAs (lncRNAs) revealed that H19 lncRNA was much higher in estrogen receptor (ER)-positive MCF-7 breast cancer cells than in ER-negative MDA-MB-231 cells. 17ß-estradiol produced a dose- and time-dependent induction of H19 expression in MCF-7 cells, which was mediated via ERα as evident by the blockade of this 17ß-estradiol effect with ICI 182780, a specific ER antagonist and knockdown of ERα using specific RNAi. Moreover, knockdown of H19 lncRNA decreased cell survival and blocked estrogen-induced cell growth while overexpression of H19 lncRNA stimulated cell proliferation. Quantitation of H19 lncRNA in human breast cancer tissues showed that the level of H19 lncRNA was >10-fold higher in ER-positive than in ER-negative tumor tissues. These results suggest that H19 is an estrogen-inducible gene and plays a key role in cell survival and in estrogen-induced cell proliferation in MCF-7 cells, indicating that H19 lncRNA may serve as a biomarker for breast cancer diagnosis and progression, and as a valuable target for breast cancer therapy.

[Distinct effect of Wansheng Huafeng Dan containing ardisia crenata on renal transporters, mercury accumulation and Kim-1 expression from mercuric chloride].

To study the effect of Wansheng Huafeng Dan (WSHFD) and mercuric chloride on renal mercury (Hg) extraction transporters (Oat1, Oct2), renal mercury excretion transporters (Mrp4, Mate2K), renal mercury accumulation and kidney injury molecule-1 (Kim-1). The ancient prescription of WSHFD containing 10-fold Hg caused much lower renal mercury accumulation and renal toxicity than HgCl2 in rats, with less effect on renal transporters than HgCl2. The above indicators had no significant difference in WSHFDO, WSHFD2 and WSHFD3 groups, indicating no effect of WSHFD with reduced or no cinnabar.

Age- and sex-related differences of organic anion-transporting polypeptide gene expression in livers of rats.

Organic anion-transporting polypeptides (Oatps) play important roles in transporting endogenous substances and xenobiotics into the liver and are implicated in drug-drug interactions. Many factors could influence their expression and result in alterations in drug disposition, efficacy and toxicity. This study was aimed to examine the development-, aging-, and sex-dependent Oatps expression in livers of rats. The livers from SD rats during development (-2, 1, 7, 14, 21, 28, 35, and 60 d) and aging (60, 180, 540 and/or 800 d) were collected and total RNAs were extracted, purified, and subjected to real-time PCR analysis. Total proteins were extracted for western-blot analysis. Results showed that Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 were all hardly detectable in fetal rat livers, low at birth, rapidly increased after weaning (21 d), and reached the peak at 60 d. The Oatps remained stable during the age between 60-180 d, and decreased at elderly (540 and/or 800 d). After birth, Oatp1a1, Oatp1a4, and Oatp1b2 were all highly expressed in liver, in contrast, Oatp1a5 expression was low. Oatp expressions are male-predominant in rat livers. In the livers of aged rats, the Oatp expression decreased and shared a consistent ontogeny pattern at the mRNA and protein level. In conclusion, this study showed that in rat liver, Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 gene expressions are influenced by age and gender, which could provide a basis of individual variation in drug transport, metabolism and toxicity in children, elderly and women.

Induction of Nrf2 and metallothionein as a common mechanism of hepatoprotective medicinal herbs.

Many Chinese medicines have the potential to be hepatoprotective and therefore can be used to treat acute and chronic liver diseases. The challenge is to identify the molecular target for their protective mechanism. This study investigated the induction of nuclear factor-erythroid 2(NF-E2)-related factor 2 (Nrf2) antioxidant genes and metallothionein as a common mechanism of hepatoprotective effects of Chinese medicines such as Piper puberulum. Mice were pretreated with Piper puberulum extract (PPE, 500 mg/kg, po) or vehicles for seven days, followed by intoxication with CCl 4 (25 µl/kg, ip for 16 h), D-galactosamine (800 mg/kg, ip for 8 h), or acetaminophen (400 mg/kg, ip for 8 h). Hepatotoprotection was evaluated by serum enzyme activities and histopathology. To determine the mechanism of protection, mice were given PPE (250-1000 mg/kg, po for seven days) and livers were collected to quantify the expression of Nrf2-targeted genes and metallothionein. Nrf2-null mice were also used to determine the role of Nrf2 in PPE-mediated hepatoprotection.PPE pretreatment protected against the hepatotoxicity produced by CCl 4, D-galactosamine, and acetaminophen, as evidenced by decreased serum enzyme activities and ameliorated liver lesions. PPE treatment increased the expression of hepatic Nrf2, NAD(P)H:quinone oxidoreductase1 (Nqo1), heme oxygenase-1 (Ho-1), glutamate-cysteine ligases (Gclc), and metallothionein (MT), at both transcripts and protein levels. PPE protected wild-type mice from CCl 4 and acetaminophen hepatotoxicity, but not Nrf2-null mice, fortifying the Nrf2-dependent protection. In conclusion, induction of the Nrf2 antioxidant pathways and metallothionein appears to be a common mechanism for hepatoprotective herbs such as PPE.

Rutaecarpine effects on expression of hepatic phase-1, phase-2 metabolism and transporter genes as a basis of herb-drug interactions.

ETHNOPHARMACOLOGICAL RELEVANCE: Rutaecarpine is an alkaloid of Evodia rutaecarpa which is traditionally used to treat human diseases. Rutaecarpine has been used in combination with other drugs in the treatment of disorders and found to produce herb-drug interactions. The basis of these herb-drug interactions is not completely understood. AIM OF STUDY: To examine the effects of rutaecarpine on the expression of drug processing genes, including Phase-1 (P450 enzyme genes), Phase-2 (glucuronidation and sulfation genes) and Phase-3 (drug transporters) in liver of mice. MATERIALS AND METHODS: Mice were orally administered rutaecarpine at the doses of 10, 20, and 30 mg/kg for consecutive 7 days. Twenty-four hours after the last dose, blood and liver were collected. Total RNA was isolated, purified, and subjected to real-time RT-PCR analysis of genes of interest. RESULTS: Rutaecarpine administration induced Cyp1a2, 2b10 and 2e1 as previously reported. Cyp3a11 and Cyp4a10 were also induced. For phase-2 enzyme genes, rutaecarpine increased glucuronyltransferases (Ugt1a1 and Ugt1a6), but had no effects on sulfotransferase (Sult1a1 and Sult1b1). Most interestingly, rutaecarpine increased hepatic uptake of organic anion transporting peptides (Oatp1a1, Oayp1a4, Oatp1b2, and Oatp2b1) and induced efflux transporter such as multidrug resistance-associated proteins (Mrp1, Mrp2, Mrp3, and Mrp4), especially at the doses of 20mg/kg and above. CONCLUSION: The interactions of rutaecarpine with drugs involve not only the induction of cytochrome P450 enzyme genes, but also the induction of hepatic transporters and phase-2 enzyme genes. The effects of rutaecarpine on these drug processing genes could play integrated roles in producing herb-drug interactions.