Tumor suppressor cell adhesion molecule 1 (CADM1) is cleaved by a disintegrin and metalloprotease 10 (ADAM10) and subsequently cleaved by γ-secretase complex

Cell adhesion molecule 1 (CADM1) is a type I transmembrane glycoprotein expressed in various tissues. CADM1 is a cell adhesion molecule with many functions, including roles in tumor suppression, apoptosis, mast cell survival, synapse formation, and spermatogenesis. CADM1 undergoes membrane-proximal cleavage called shedding, but the sheddase and mechanisms of CADM1 proteolysis have not been reported. We determined the cleavage site involved in CADM1 shedding by LC/MS/MS and showed that CADM1 shedding occurred in the membrane fraction and was inhibited by tumor necrosis factor-α protease inhibitor-1 (TAPI-1). An siRNA experiment revealed that ADAM10 mediates endogenous CADM1 shedding. In addition, the membrane-bound fragment generated by shedding was further cleaved by γ-secretase and generated CADM1-intracellular domain (ICD) in a mechanism called regulated intramembrane proteolysis (RIP). These results clarify the detailed mechanism of membrane-proximal cleavage of CADM1, suggesting the possibility of RIP-mediated CADM1 signaling.     

Heat shock protein 90β stabilizes focal adhesion kinase and enhances cell migration and invasion in breast cancer cells

Focal adhesion kinase (FAK) acts as a regulator of cellular signaling and may promote cell spreading, motility, invasion and survival in malignancy. Elevated expression and activity of FAK frequently correlate with tumor cell metastasis and poor prognosis in breast cancer. However, the mechanisms by which the turnover of FAK is regulated remain elusive. Here we report that heat shock protein 90β (HSP90β) interacts with FAK and the middle domain (amino acids 233–620) of HSP90β is mainly responsible for this interaction. Furthermore, we found that HSP90β regulates FAK stability since HSP90β inhibitor 17-AAG triggers FAK ubiquitylation and subsequent proteasome-dependent degradation. Moreover, disrupted FAK-HSP90β interaction induced by 17-AAG contributes to attenuation of tumor cell growth, migration, and invasion. Together, our results reveal how HSP90β regulates FAK stability and identifies a potential therapeutic strategy to breast cancer.     

p38α MAPK mediates 17β-estradiol inhibition of MMP-2 and -9 expression and cell migration in human lovo colon cancer cells

Epidemiological studies demonstrate that the incidence and mortality rates of colorectal cancer in women are lower than in men. However, it is unknown if 17β‐estradiol (E₂) treatment is sufficient to inhibit cell proliferation and cell migration in human colon cancer cells. Up‐regulation of urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA), and matrix metallopeptidases (MMPs) is reported to associate with the development of cancer cell mobility, metastasis, and subsequent malignant tumor. In the present study, we treated human LoVo colon cancer cells with E₂ to explore whether E₂ down‐regulates cell proliferation and migration, and to identify the precise molecular and cellular mechanisms behind the down‐regulatory responses. Here, we found that E₂ treatment decreased cell proliferation and cell cycle‐regulating factors such as cyclin A, cyclin D1 and cyclin E. At the same time, E₂ significantly inhibited cell migration and migration‐related factors such as uPA, tPA, MMP‐2, and MMP‐9. However, E₂ treatment showed no effects on upregulating expression of plasminogen activator inhibitor‐1 (PAI‐1), tissue inhibitor of metalloproteinase‐1, ‐2, ‐3, and ‐4 (TIMP‐1, ‐2, ‐3, and ‐4). After administration of inhibitors including QNZ (NFκB inhibitor), LY294002 (Akt activation inhibitor), U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor) or SP600125 (JNK1/2 inhibitor), E₂‐downregulated cell migration and expression of MMP‐2 and MMP‐9 in LoVo cells is markedly inhibited only by p38 MAPK inhibitors, SB203580. Application of specific target gene siRNA (ERα, ERβ, p38α, and p38β) to LoVo cells further confirmed that p38 MAPK mediates E₂/ERs inhibition of MMP‐2 and ‐9 expression and cell motility in LoVo cells. Collectively, these results suggest that E₂ treatment down‐regulates cell proliferation by modulating the expression of cyclin A, cyclin D1 and cyclin E. E₂ treatment simultaneously impaired cell migration by inhibiting the expression of uPA, tPA, MMP‐2, and MMP‐9 through E₂/ERs ? p38α MAPK signaling pathway in human LoVo colon cancer cells. J. Cell. Physiol. 227: 3648–3660, 2012. © 2012 Wiley Periodicals, Inc.     

JNK suppression is essential for 17β-Estradiol inhibits prostaglandin E2-Induced uPA and MMP-9 expressions and cell migration in human LoVo colon cancer cells

Background  

Epidemiological studies demonstrate that the incidence and mortality rates of colorectal cancer in women are lower than in men. However, it is unknown if 17β-estradiol treatment is sufficient to inhibit prostaglandin E2 (PGE2)-induced cellular motility in human colon cancer cells.     

HT-29 human colon cancer cell proliferation is regulated by cytosolic phospholipase A(2)α dependent PGE(2)via both PKA and PKB pathways

Cytosolic phospholipase A(2)α (cPLA(2)α) up-regulation has been reported in human colorectal cancer cells, thus we aimed to elucidate its role in the proliferation of the human colorectal cancer cell line, HT-29. EGF caused a rapid activation of cPLA(2)α which coincided with a significant increase in cell proliferation. The inhibition of cPLA(2)α activity by pyrrophenone or by antisense oligonucleotide against cPLA(2)α (AS) or inhibition of prostaglandin E(2) (PGE(2)) production by indomethacin resulted with inhibition of cell proliferation, that was restored by addition of PGE(2). The secreted PGE(2) activated both protein kinase A (PKA) and PKB/Akt pathways via the EP2 and EP4 receptors. Either, the PKA inhibitor (H-89) or the PKB/Akt inhibitor (Ly294002) caused a partial inhibition of cell proliferation which was restored by PGE(2). But, inhibited proliferation in the presence of both inhibitors could not be restored by addition of PGE(2). AS or H-89, but not Ly294002, inhibited CREB activation, suggesting that CREB activation is mediated by PKA. AS or Ly294002, but not H-89, decreased PKB/Akt activation as well as the nuclear localization of β-catenin and cyclin D1 and increased the plasma membrane localization of β-catenin with E-cadherin, suggesting that these processes are regulated by the PKB pathway. Similarly, Caco-2 cells exhibited cPLA(2)α dependent proliferation via activation of both PKA and PKB/Akt pathways. In conclusion, our findings suggest that the regulation of HT-29 proliferation is mediated by cPLA(2)α-dependent PGE(2) production. PGE(2)via EP induces CREB phosphorylation by the PKA pathway and regulates β-catenin and cyclin D1 cellular localization by PKB/Akt pathway.     

17β-Estradiol inhibits prostaglandin E2-induced COX-2 expressions and cell migration by suppressing Akt and ERK1/2 signaling pathways in human LoVo colon cancer cells

Epidemiological studies demonstrate that the incidence and mortality rates of colorectal cancer in women are lower than in men. However, it is unknown if 17β-estradiol treatment is sufficient to inhibit prostaglandin E2 (PGE2)-induced cellular motility in human colon cancer cells. Upregulation of cyclooxygenase-2 (COX-2) is reported to associate with the development of cancer cell mobility, metastasis, and subsequent malignant tumor. After administration of inhibitors including LY294002 (Akt activation inhibitor), U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), or QNZ (NFκB inhibitor), we found that PGE2 treatment increases COX-2 via Akt and ERK1/2 pathways, thus promoting cellular motility in human LoVo cancer cells. We further observed that 17β-estradiol treatment inhibits PGE2-induced COX-2 expression and cellular motility via suppressing activation of Akt and ERK1/2 in human LoVo cancer cells. Collectively, these results suggest that 17β-estradiol treatment dramatically inhibits PGE2-induced progression of human LoVo colon cancer cells.     

The effects of genistein and daidzein on cell proliferation kinetics in HT29 colon cancer cells: the expression of CTNNBIP1 (β-catenin), APC (adenomatous polyposis coli) and BIRC5 (survivin)

Soybean isoflavonoids have received significant attention due to their potential anticarcinogenic and antiproliferative effects and possible role in many signal transduction pathways. However, their mechanisms of action and their molecular targets remain to be further elucidated. In this paper, we demonstrated that two soybean isoflavones (genistein and daidzein) reduced the proliferation of the human colon adenocarcinoma grade II cell line (HT-29) at concentrations of 25 and 50–100 μM, respectively. We then investigated the effects of genistein and daidzein by RT-PCR on molecules that involved in tumor development and progression by their regulation of cell proliferation. At a concentration of 50 μM genistein, there was suppressed expression of β-catenin (CTNNBIP1). Neither genistein nor daidzein affected APC (adenomatous polyposis coli) or survivin (BIRC5) expression when cells were treated with concentrations of 10 or 50 μM. These data suggest that the down-regulation of β-catenin by genistein may constitute an important determinant of the suppression of HT-29 cell growth and may be exploited for the prevention and treatment of colon cancer.     

UV radiation resistance-associated gene (UVRAG) promotes cell proliferation,migration, invasion by regulating cyclin-dependent kinases (CDK) and integrin-β/Src signaling in breast cancer cells

Breast cancer is a highly heterogeneous group of human cancer with distinct genetic, biological and clinicopathological features. Triple-negative breast cancer (TNBC) is the most aggressive and metastatic type of breast cancer and associated with poor patient survival. However, the role of UV Radiation Resistance-Associated Gene (UVRAG) in TNBC remains unknown. Here, we report that UVRAG is highly upregulated in all TNBC cells and its knockdown leads to the inhibition of cell proliferation, colony formation and progression of cell cycle, which is associated with and reduced expression of cell cycle related protein expression, including Cyclin A2, B1, D1, cdc2 and cdk6 in TNBC cells. Inhibition of UVRAG also suppressed cell motility, migration and invasion of TNBC cells by inhibition of Integrin β1 and β3 and Src activity. Our findings suggest for the first time that UVRAG expression contributes to proliferation, cell cycle progression, motility/migration and invasion of TNBC cells. Thus, targeting UVRAG could be a potential strategy in breast cancer especially against TNBC.

     

A novel antioestrogen agent (3R,6R)-bassiatin inhibits cell proliferation and cell cycle progression by repressing cyclin D1 expression in 17β-oestradiol-treated MCF-7 cells

Bassiatin [(3R,6R)-bassiatin] was isolated from the endogenous fungus Fusarium oxysporum J8-1-2. We found that oestrogen-dependent cell growth was inhibited by bassiatin in MCF-7 ERα (oestrogen receptor α)-positive breast cancer cells. In addition, the mRNA and protein levels of ERα and the oestrogen-responsive gene cyclin D1 were down-regulated by bassiatin in the presence of 17β-oestradiol. Co-treatment of 17β-oestradiol and bassiatin increased phospho-cyclin D1 (Thr286), an indicator of cyclin D1 phosphorylation-dependent degradation. However, this effect was not obvious in the absence of 17β-oestradiol, suggesting that bassiatin may play a role in the metabolism of cyclin D1 by decreasing cyclin D1 protein expression in the presence of 17β-oestradiol. Cyclin D1, known as a key cell cycle regulator, regulates the transition of G1- and S-phase. Decreased cyclin D1 was found to be involved in bassiatin-induced MCF-7 cell cycle arrest. Collectively, our study showed that bassiatin induced cell cycle arrest and exerted an antioestrogen effect. It may prove to be a potential drug target for antioestrogen therapy in ERα-positive breast cancer.