Characterization of Basigin Isoforms and the Inhibitory Function of Basigin-3 in Human Hepatocellular Carcinoma Proliferation and Invasion

Abstract

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.

A Regulatory Loop Involving miR-22, Sp1, and c-Myc Modulates CD147 Expression in Breast Cancer Invasion and Metastasis

“…Several studies have clearly shown a key role for CD147 in tumor progression and metastasis. Indeed, high CD147 expression levels have been reported in many tumors, including breast cancer, lymphoma, oral squamous cell carcinoma, glioma, melanoma, lung, bladder, liver, and kidney carcinomas (5)(6)(7). Accordingly, CD147 expression has been associated with known risk factors for breast cancer and with poor prognosis in patients with breast cancer (8)(9)(10).…”

“…Anti-CD147 mAb was prepared by our laboratory (7). Primary antibodies against Sp1, c-Myc, or tubulin were from Santa Cruz.…”

“…The expression of miR-22 was quantified by TaqMan microRNA assays from Applied Biosystems. Expression data were uniformly normalized to either U6 or GAPDH as an internal control, and the relative expression levels were evaluated using the DDC t method (7,28). Primers are listed in Supplementary Table S1.…”

Regulation of invadopodia formation and activity by CD147

“…It is usually expressed at low levels in most normal tissues, but is highly upregulated during dynamic cellular events, such as tissue remodeling and cancer progression (Gabison et al, 2009;Nabeshima et al, 2006;Yan et al, 2005). Emmprin was originally identified as a cell surface factor that induces MMP production in stromal cells (Ellis et al, 1989;Kataoka et al, 1993), but later studies revealed that emmprin is identical to basigin-2 (Biswas et al, 1995;Liao et al, 2011), and is multifunctional; it is now widely known as CD147. CD147 induces several MMPs at both the mRNA and protein level, including MMP1, MMP2, MMP3, MMP9, MT1-MMP and MT2-MMP, although there is variation in the particular MMPs induced in different systems Yan et al, 2005).…”

A Novel Marker for Undifferentiated Human Embryonic Stem Cells

“…(7) Functional analyses have revealed the involvement of CD147/basigin in energy metabolism, reproduction, development, and tumor invasion. (8) To discover novel cell surface molecules expressed on hESCs, we generated a panel of monoclonal antibodies (MAbs) against undifferentiated hESCs using the mouse medial iliac lymph node method. This study describes the biochemical characterization and identification of the hESC surface molecule that is recognized by MAb2.…”