Original ArticlesIdentification of miRNomes in human stomach and gastric carcinoma reveals miR-133b/a-3p as therapeutic target for gastric cancer
Introduction
Gastric cancer (GC) is the fourth most frequent malignant disease and the second leading cause of cancer mortality worldwide [1]. Although GC patients benefit from earlier diagnosis, standardized surgical resection and chemotherapy in the past few decades, the overall survival remains far from satisfactory [2]. Currently, GC was recognized as a biologically heterogeneous disease characterized by complex genetic and epigenetic alterations [3], [4], [5]. Therefore, a better understanding of the cellular and molecular mechanisms underlying GC development and progression could provide insights leading to improved diagnosis and therapeutic approaches.
MicroRNAs (miRNAs) represent a large family of endogenous noncoding RNAs involved in a fundamental layer of post-transcriptional regulation of gene expression [6]. They function to regulate gene expression by directly binding to the 3′ untranslational region (3′-UTR) of their target mRNAs. Numerous studies have revealed that miRNAs play crucial roles in a number of biological processes, including development, infection, immune responses, and carcinogenesis [7], [8], [9]. Although accumulating evidence indicates that miRNAs are frequently dysregulated in human cancers [10], [11], the molecular mechanisms by which miRNAs modulate the process of carcinogenesis and the behavior of cancer cells remain largely unknown. In the past few years, a wide variety of miRNAs have been found to participate in carcinogenesis via altering expressions of oncogenes and tumor suppressor genes to affect cell proliferation, apoptosis, motility and invasion [12], [13]. Meanwhile, some miRNAs are closely associated with malignant phenotypes, tumor stages, or patient survival, making them potential diagnostic or prognostic markers [14].
The sequence of miR-133 was first experimentally characterized in mice [15]. In the human genome there are three known miR-133 genes: miR-133a-1, miR-133a-2 and miR-133b, which are found on chromosomes 18, 20 and 6 respectively [16]. The mature sequences of miR-133a-3p and miR-133b were excised from the3′ arm of the pri-miRNA hairpin, but miR-133b does not have 3′ arm excised segment. The mature sequences of miR-133a-3p and miR-133b are highly homologous and only showed single base difference at 3′ end [17]. Previously, miR-133 was believed to be muscle-specific and plays a critical role in the regulation of muscle development. Therefore, its aberrant expression is linked to many diseases in skeletal muscle and cardiac muscle [18]. Beyond these observations, studies examining the expression of miRNA in clinical samples have established a link between miR-133 function and carcinogenesis, including bladder cancer [19], prostate cancer [20], and GC [21]. However, the accurate molecular mechanisms and therapeutic roles of miR-133 in GC are largely unknown.
In the present study, we performed a heatmap analysis of the miRNomes across TCGA datasets and found that the expression of miR-133b/a-3p was significantly downregulated in GC. We systemically validated the tumor suppressive role of miR-133b/a-3p in a series of in vitro experiments and confirmed that the downregulation of miR-133 was mainly mediated by histone modification within its promoter region. Importantly, we showed that restoration of miR-133b/a-3p expression could suppress GC cell proliferation and promoted cell apoptosis by targeting anti-apoptotic molecules Mcl-1 and Bcl-xL. Meanwhile, since miRNAs are highly stable and compatible with tissues, we explored the feasibility of using miR-133b/a-3p as a potential therapeutic approach to treat GC in a nude mice xenograft model.
Section snippets
Patients and tissue specimens
Tumor and corresponding normal stomach mucosa tissues were collected from patients with GC who underwent surgical resection at Department of Gastrointestinal Surgery, Changzheng Hospital, Second Military Medical University. None of these patients had a history of chemotherapy or radiotherapy before sampling. Individuals with multi-primary cancers were excluded. The clinical stages of tumors were determined according to the TNM classification system of the International Union Against Cancer (7th
Identification of miR-133b/a-3p as a dysregulated miRNA in GC
We firstly sought to address the expression pattern of miRNAs in GC tissues. MiRNA-Seq data that comprise 14 GC samples were downloaded from the Cancer Genome Atlas (TCGA) datasets and a heatmap analysis of the miRNomes was undertaken. Results showed that miR-133a-1, miR-133a-2 and miR-133b were significantly downregulated in tumor tissues compared with control normal stomach tissues (Fig. 1A). Then, the expression miR-133b/a-3p, which is the mature miR-133, was determined by qRT-PCR analysis
Discussion
Herein, we performed a heatmap analysis of the miRNomes across TCGA datasets to identify miR-133b/a-3p as a GC-specific miRNA. Thereafter, using a series of in vitro and in vivo assays, we demonstrated that miR-133b/a-3p acted as a critical tumor suppressor in human stomach tissue. Although decreased miR-133b/a-3p expression has been reported previously in human cancers, the present study provided a novel and comprehensive insight into the functional role and molecular mechanisms of
Funding
This work was supported by grants from the National Natural Science Foundation of China (No. 81402359 and No. 81372670), and Initiation Foundation For Young Scientist of Changzheng Hospital (No. 2013CZQN05).
Conflict of interest
The authors have no conflict of interest to declare.
References (33)
MicroRNAs: target recognition and regulatory functions
Cell
(2009)- et al.
Regulation of miRNA biogenesis as an integrated component of growth factor signaling
Curr. Opin. Cell Biol
(2013) - et al.
MicroRNAs in the pathogenesis of cancer
Semin. Oncol
(2011) - et al.
Identification of tissue-specific microRNAs from mouse
Curr. Biol
(2002) - et al.
MiR-133a induces apoptosis through direct regulation of GSTP1 in bladder cancer cell lines
Urol. Oncol
(2013) - et al.
miR-133 is a key negative regulator of CDC42-PAK pathway in gastric cancer
Cell. Signal
(2014) - et al.
Identification of miRNomes in human liver and hepatocellular carcinoma reveals miR-199a/b-3p as therapeutic target for hepatocellular carcinoma
Cancer Cell
(2011) - et al.
Induction of Siglec-G by RNA viruses inhibits the innate immune response by promoting RIG-I degradation
Cell
(2013) - et al.
miR-133 modulates TGF-beta1-induced bladder smooth muscle cell hypertrophic and fibrotic response: implication for a role of microRNA in bladder wall remodeling caused by bladder outlet obstruction
Cell. Signal
(2015) - et al.
Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008
Int. J. Cancer
(2010)
Cancer statistics, 2013
CA Cancer J. Clin
Epigenetic alterations in gastric carcinogenesis
Cell Res
Genetics of gastric cancer
Nat. Rev. Gastroenterol. Hepatol
Gastric cancer-molecular and clinical dimensions
Nat. Rev. Clin. Oncol
MicroRNA-mediated regulation of T helper cell differentiation and plasticity
Nat. Rev. Immunol
Targeting viral infection by microRNA inhibition
Genome Biol
Cited by (36)
Myeloid cell leukemia 1 (MCL-1): Structural characteristics and application in cancer therapy
2021, International Journal of Biological MacromoleculesCitation Excerpt :Expression of miR-133b/a-3p has been shown as a tumor suppressor in gastric cancer. Reintroduction of miR-133b/a-3p expression in gastric cancer cell lines decreased MCL-1 and BCL-xL protein levels via translational inhibition [97]. The dysregulation of miRNA expression and its impact on patient survival and clinical response is extensively studied [98].
Estradiol deficiency and skeletal muscle apoptosis: Possible contribution of microRNAs
2021, Experimental GerontologyCitation Excerpt :Furthermore, restoring miR-133a/b has been proposed to be a key therapeutic target for gastric cancer treatment in humans (Liu et al., 2015). It seems that miR-133a acts as a tumor-suppressor in cancer cells by targeting BCL-XL and CASP9 (Liu et al., 2015; He et al., 2011). Similarly, with miRs 122-5p and 133a-3p, upregulation of miR-214-3p is associated with downregulation of BCL-W and vice versa, suggesting a pro-apoptotic role of miR-214-3p (Fan and Wu, 2017).
Characterization of serum cytokines and circulating microRNAs that are predicted to regulate inflammasome genes in cutaneous leishmaniasis patients
2020, Experimental ParasitologyCitation Excerpt :Our data showed a differential expression of the microRNAs miR-7-5p, miR-133a, miR-146b, miR-223, and miR 328–3p, which may be related to pathogen-host interaction in cutaneous leishmaniasis. When predicting possible target genes, we identified several that were related to inflammasomes, such as NLRP3 in the miR-223, a protein involved in inflammasome assembly, and BCL2L1 and UCP2 in the miR-133a, an anti- or pro-apoptotic regulator involved in NLR receptor signaling and a protein that negatively controls inflammasomes activities, respectively (F. Bauernfeind et al., 2012; Gupta et al., 2017; Liu et al., 2015a). In addition, we identified possible target genes in the miR-146b, such as TRAF6 and IRAK1, which are known to be involved in the immune response mediated by TLRs (toll like receptors) (Park et al., 2015).
MiR-133a acts as an anti-oncogene in Hepatocellular carcinoma by inhibiting FOSL2 through TGF-β/Smad3 signaling pathway
2018, Biomedicine and PharmacotherapyInteraction of ncRNA and Epigenetic Modifications in Gastric Cancer: Focus on Histone Modification
2022, Frontiers in Oncology
- 1
These authors contributed equally to this work.