Breast cancer is the most common cancer in women for which the metastatic process is still poorly understood. CD147 is upregulated in breast cancer and has been associated with tumor progression, but little is known about its regulatory mechanisms. In this study, we demonstrated that CD147 was overexpressed in breast cancer tissues and cell lines, and the high expression correlated with tumor invasion and metastasis. We also found that the transcription factors Sp1 and c-Myc could bind to the CD147 promoter and enhance its expression. The CD147 mRNA has a 748-bp 3 0 -untranslated region (UTR) with many miRNA target sites, suggesting possible regulation by miRNAs. We discovered that miR-22 repressed CD147 expression by directly targeting the CD147 3 0 UTR. We also determined that miR-22 could indirectly participate in CD147 modulation by downregulating Sp1 expression. miR-22 could form an autoregulatory loop with Sp1, which repressed miR-22 transcription by binding to the miR-22 promoter. Together with the c-Myc-mediated inhibition of miR-22 expression, our investigation identified a miR-22/Sp1/c-Myc network that regulates CD147 gene transcription. In addition, miR-22 overexpression suppressed breast cancer cell invasion, metastasis, and proliferation by targeting CD147 in vitro and in vivo. Furthermore, we found that miR-22 was significantly downregulated in breast cancer tissues and that its expression was inversely correlated with the tumor-node-metastasis stage and lymphatic metastasis in patients. Our study provides the first evidence that an miR-22/Sp1/c-Myc network regulates CD147 upregulation in breast cancer and that miR-22 represses breast cancer invasive and metastatic capacities. Cancer Res; 74(14); 3764-78. Ó2014 AACR.

Basigin, which has four isoforms, plays an important role in invasion of hepatocellular carcinoma (HCC).Detailed transcriptional regulation and functions of the basigin isoforms have not been reported except in the case of the predominant isoform basigin-2, which act as inducer of matrix metalloproteinases (MMPs). Here we determined that basigin-2, basigin-3, and basigin-4 were the most abundant transcript variants in human cell lines. GeneRacer PCR and luciferase reporter assays showed that basigin-3 and basigin-4 were initiated from an alternative promoter. Basigin-3 and basigin-4 were widely expressed in various normal human tissues at the mRNA level and were upregulated in HCC tissues compared to in normal tissues. Western blotting and confocal imaging showed that glycosylated basigin-3 and basigin-4 were expressed and localized to the plasma membrane. However, in cultured cell lines, only native basigin-3, and not basigin-4, was detected at protein level. Overexpression of basigin-3 inhibited HCC cell proliferation, MMP induction, and cell invasion in vitro and in vivo. Bimolecular fluorescence complementation assays and nuclear magnetic resonance (NMR) analysis indicated that basigin-3 interacted with basigin-2 to form hetero-oligomers. In conclusion, we systematically investigated the alternative splicing of basigin and found that basigin-3 could inhibit HCC proliferation and invasion, probably through interaction with basigin-2 as an endogenous inhibitor via hetero-oligomerization.

CD147 is a novel cancer-associated biomarker that plays an important role in the invasion and metastasis of human lung cancer. In spite of its many known functions, little is known about CD147 transcriptional regulation. In this study, we explored the regulation of CD147 in human lung cancer tissues. Over 60% of the human lung cancer tissues expressed differential high levels of CD147. We then cloned the 5¢-flanking region of the human CD147 gene and identified a critical promoter region at )108 to -42 which contained one binding site for Sp1, which was essential in up-regulating CD147 promoter activity. These results were proven by blocking Sp1 using RNAi or mithramycin A treatment and up-regulating Sp1 using transfection with eukaryotic expression vector. Consistent with the CD147 transcription activation, a high level of Sp1 expression was detected in lung cancer cell lines overexpressing CD147. Chromatin immunoprecipitation assay showed that much more Sp1 could bind to the CD147 promoter in 95-D with CD147 high expression than in SK-MES-1 with CD147 low expression. There was a significant positive correlation between CD147 expression and Sp1 expression level detected by immunohistochemistry (r = 0.831). Collectively, our results suggest that Sp1 is essential for regulating the CD147 gene expression in human lung

Activation of hepatic stellate cells (HSCs) by transforming growth factor-β1 (TGF-β1) initiates HBV-associated fibrogenesis. The mechanism of TGF-β1 modulating HSC activation is not fully uncovered. We hypothesized a positive feedback signaling loop of TGF-β1-CD147 promoting liver fibrogenesis by activation of HSCs. Human HSC cell line LX-2 and spontaneous liver fibrosis model derived from HBV transgenic mice were used to evaluate the activation of molecules in the signaling loop. Wound healing and cell contraction assay were performed to detect the CD147-overexpressed HSC migration and contraction. The transcriptional regulation of CD147 by TGF-β1/Smad4 was determined using dual-luciferase reporter assay and chromatin immunoprecipitation. We found that a positive reciprocal regulation between TGF-β1 and CD147 mediated HSC activation. CD147 over-expression promoted HSC migration and accelerated TGF-β1-induced cell contraction. Phosphorylation of Smad2 and Smad3 in cooperation with Smad4 mediated the TGF-β1-regulated CD147 expression. Smad4 activated the transcription by direct interaction with CD147 promoter. Meanwhile, CD147 modulated the activated phenotype of HSCs through the ERK1/2 and Sp1 which up-regulated α-SMA, collagen I, and TGF-β1 synthesis. These findings indicate that TGF-β1-CD147 loop plays a key role in regulating the HSC activation and combination of TGF-β receptor inhibitor and anti-CD147 antibody might be promised to reverse fibrogenesis.

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BackgroundRecently, miR-10b is identified as a miRNA highly expressed in many human cancers, promoting cell migration and invasion. However, the specific function of miR-10b in hepatocellular carcinoma (HCC) is unclear at this point.MethodsThe miR-10b expression levels in 60 paired different TNM Stage HCC tumor tissues compared with adjacent non-tumor (ANT) tissues, normal tissue control (8 benign tumor and 7 normal liver tissues), 3 normal liver and 7 HCC cell lines were measured by real-time quantitative RT-PCR and to evaluate their association with HCC clinicopathologic features. Invasion assay, MTT proliferation assay and wound-healing assay were performed to test the invasion and proliferation of HCC cell after transfection. The effect of miR-10b on HCC in vivo was validated by murine xenograft model.ResultsWe found that miR-10b expression was increased in human HCC tissues and cell lines compared with normal control, respectively. The expression of miR-10b was correlated with HCC metastatic ability. Overexpression of miR-10b in MHCC-97L cells increased cell motility and invasiveness, whereas inhibition of miR-10b in MHCC-97H cells reduced cell motility and invasiveness in vitro and in vivo. We also showed that HOXD10 was negatively regulated by miR-10b at the posttranscriptional level, via a specific target site within the 3′UTR by luciferase reporter assay. Furthermore, we found that miR-10b induced HCC cell invasion and migration by modulating the HOXD10 target gene RhoC, uPAR, MMP-2 and MMP-9 expression.ConclusionsOur results suggested that miR-10b was overexpressed in HCC and promoted HCC cell migration and invasion through the HOXD10/ RhoC/ uPAR/ MMPs pathway which may provide a novel bio-target for HCC therapy.

CD147 is a transmembrane glycoprotein overexpressed in human hepatocellular carcinoma (HCC) which could promote HCC progression and metastasis. Promoter methylation is one of the most important processes in gene regulation. In this study, we aim to investigate CD147 promoter methylation status and the correlation with clinicopathological features and prognosis in HCC. CD147 promoter methylation statuses and expression levels in normal and HCC cell lines and 54 paired HCC and adjacent non-tumour (ANT) tissues were, respectively, examined by bisulphite genomic sequencing, methylation-specific PCR, real-time RT-PCR, Western blot and immunohistochemistry. The correlations of promoter methylation statuses with CD147 expression level and the clinicopathological features were statistically analysed in HCC patients. Significantly higher expression of CD147 and significantly lower promoter methylation level were observed in HCC cell lines compared to normal cell lines and tissues control. In vivo and in vitro analysis indicated that demethylation with 5-Aza-2′-deoxycytidine led to increased CD147 expression through enhancing Sp1 binding affinity, and methylation with methyltransferase reduced CD147 transcriptional activity through interfering Sp1 binding. CD147 promoter methylation level in HCC tissues (22.22%) was lower than that in ANT tissues (46.30%; P < 0.05). Within HCC tissues, a significant inverse correlation was observed between CD147 expression and methylation level (r=−0.615). Moreover, HCC patients with unmethylated CD147 promoter had a significantly higher recurrence rate (88.1%versus 58.3%; P < 0.05) and death rate (83.3%versus 50.0%; P < 0.05) than patients with methylated CD147 promoter. In conclusions, promoter hypomethylation up-regulates CD147 expression primarily through increasing Sp1 binding and associates with poor prognosis in HCC patients.

The hepatocellular carcinoma‐associated antigen HAb18G/CD147, a member of CD147 family, could promote tumour invasion and metastasis via inducing the secretion of matrix metalloproteinases (MMP). Anti‐CD147 monoclonal antibodies (MoAb) have exhibited obvious inhibitory effect on MMP induction. However, none of the epitopes of these MoAb has been reported. We previously prepared five MoAb against HAb18G/CD147, named HAb18, 3B3, 1B3, 5A5 and 4D2. To map the epitopes of these MoAb, a series of truncated fragments of extracellular region of HAb18G/CD147 was expressed in Escherichia coli and the MoAb‐binding affinity to these fragments was examined with an enzyme‐linked immunosorbent assay and Western blot. The residues 39LTCSLNDSATEV50, 36KILLTCS42 and 22AAGTVFTTVEDL33 were determined to be the epitopes of HAb18, 3B3 and 1B3, respectively, which were further proved by a dot‐blot analysis with synthesized peptides and bioinformatics epitope prediction. The binding regions of MoAb 5A5 and 4D2 were located at residues E120–R203. Then we constructed and expressed full‐length HAb18G/CD147 and truncated HAb18G/CD147 without residues A22–V50 in COS‐7 cells. Gelatin zymography and Boyden chamber assay showed that the COS‐7 cells expressing truncated HAb18G/CD147 failed to induce MMP production and enhance the cells’ invasive potential, compared with the cells expressing full‐length HAb18G/CD147. Taken together with the obviously inhibitory effects of HAb18 on the function of full‐length HAb18G/CD147, these findings suggest that residues 22AAGTVFTTVEDLGSKILLTCSLNDSATEV50 may play a critical role in the functions of HAb18G/CD147 on MMP secretion and tumour invasion. These key residues can be used as potential drug target in cancer therapy.