Expression of WISPs and of Their Novel Alternative Variants in Human Hepatocellular Carcinoma Cells

Abstract

WISPs (Wnt-induced secreted proteins) are members of the CCN (CTGF/Cyr61/Nov) family involved in fibrotic disorders and tumorigenesis. They have a typical structure composed of four conserved cysteine-rich modular domains, but variants of CCN members lacking one or more modules, generated by alternative splicing or gene mutations, have been described in various pathological conditions. WISP genes were first described as downstream targets of the Wnt signaling pathway, which is frequently altered in human hepatocellular carcinoma (HCC). In the present study, WISP mRNA expression was analyzed by RT-PCR in four human HCC cell lines (HepG2, HuH-6, HuH-7, HA22T/VGH). Our results show for the first time that WISP1, WISP1v, and WISP3 are expressed in HCC cell lines. Moreover, we identified two novel variants, generated by alternative splicing of WISP1 and WISP3, respectively, named WISP1 delta ex3-4 and WISP3vL. Overall, our study suggests that WISP transcripts may have a role in the development of HCC, although further studies are necessary to clarify the relative importance of the expression of wild-type WISPs, as well as of their novel variants, in this tumor type.

Research on WISP1 in Lung Disease

“…Some studies have confirmed that invasive scirrhous gastric carcinoma [14] and cholangiocarcinoma [15] are related to the deletion of a module named VWC, reduced by alternative splicing of exon 3; WISP1 without the VWC module is referred to as WISP1v. Furthermore, besides full-length WISP1 and WISP1v, loss of more domains can be found in two hepatocellular carcinoma cell lines and a human chondrosarcoma-derived chondrocytic cell line, including ex 3-4 deltaWISP1 [16] and WISP1vx [17]. Models of all described WISP1 variants are shown in (Figure 2) [18].…”

“…WISP1Δex3-4 splice variant is a product of joining exons 2 and 5 with a frame shift that leads to a premature stop. As a result, the predicted protein has only the first module [16]. SP: signal peptide, IGFBP: insulin growth factor binding protein, VWC: von Willebrand Factor C, TSP1: thrombospondin type 1 repeat, CT: C-terminal domain.…”

Novel CT domain-encoding splice forms of CTGF/CCN2 are expressed in B-lineage acute lymphoblastic leukaemia

“…Alternative splicing can fine tune protein structure and abundance by controlling variable inclusion of coding information contained within exons and Cancer-associated alternative splicing of other CCN genes has been reported previously. In hepatocellular carcinoma, CCN4 (WISP1) is alternatively spliced to produce transcripts encoding (i) CCN4 protein missing the VWC domain and (ii) truncated CCN4 containing only the IGFBP domain (Cervello, Giannitrapani et al 2004). The former is also encoded by spliceforms expressed in gastric carcinoma (Tanaka, Sugimachi et al 2001), thus this cancer-associated spliceform may play an important role in the pathophysiology of these cancers.…”

“…Alternative splicing of other CCN family mRNAs including CCN1, CCN3 and CCN4 has been reported in the last decade (Perbal 2009). Furthermore WNT1/CCN4 transcript variants have been observed in gastric carcinoma, and hepatoma (Tanaka, Sugimachi et al 2001;Cervello, Giannitrapani et al 2004), while alternative CYR61 (CCN1) transcripts have been identified in breast cancer cell lines (Hirschfeld, zur Hausen et al 2009). …”

Induction of apoptosis in human bladder cancer cells by green tea catechins

“…Real-time PCR (QPCR) reactions for critical signaling pathway genes were analyzed in total RNA using the Human signal transduction RT 2 Profiler PCR array (SuperArray Biosciences Corporation, USA) according to the manufacturer's protocol. Briefly, cDNA was prepared from 1 μg total RNA using a RT 2 PCR array first strand kit (SuperArray).…”