Transfection of the mouse ICAM-1 gene into murine neuroblastoma enhances susceptibility to lysis,reduces in vivo tumorigenicity and decreases ICAM-2-dependent killing

We determined the expression of intercellular adhesion molecules (ICAM) on neuro-2a cells in order to evaluate whether they were involved in cytolysis of murine neuroblastoma. Fluorescence-activated cell sorting analysis revealed that the control neomycin-resistance-genetransduced line (neuro-2a/LN) had poor expression of ICAM-1 (mean channel fluorescence, MCF=3.7). An ICAM-1-positive transfectant of neuro-2a (neuro-2a/ICAM-1⁺) (CMF=64.3) was generated to evaluate directly the role of this adhesion molecule in cytolysis. Neuro-2a/ICAM-1⁺ was more sensitive to LAK killing (69.7% at an effector-to-target ratio of 1001) compared to neuro-2a/LN (48.6%) (P<0.001). Blocking of neuro-2a/LN and neuro-2a/ICAM-1⁺ lysis with anti-ICAM-1 monoclonal antibodies (mAbs) did not account for all the LFA-1-dependent killing. These data indicate that even in neuro-2a/ICAM-1⁺ cells, other LFA-1 ligands participated in the effector-target interaction. Therefore, we examined these cell lines for ICAM-2 expression. Both neuro-2a/LN and neuro-2a/ICAM-1⁺ lines expressed ICAM-2 (MCF=16.4 and 16.5). ICAM-2 accounted for the majority of the LFA-1-dependent killing in the ICAM-1-negative target, neuro-2a/LN, while ICAM-1 played a primary role in the cytolysis of the ICAM-1⁺ transfectant. Inhibition of lysis in the presence of anti-ICAM-1 and ICAM-2 mAbs was comparable to that seen with the addition of anti-LFA-1 mAb, indicating that other LFA-1 ligands were not involved in this system. ICAM-1 expression was associated with decreased in vivo tumorigenicity; mice inoculated with neuro-2a/ICAM-1⁺ cells had a significantly longer survival compared to those receiving neuro-2a/LN cells (median survival time 35.5 versus 24.5 days) (P<0.001). It is important to note that ICAM-1 transfection of murine neuroblastoma did not alter its metastatic potential. We conclude that transfection of mouse neuroblastome with ICAM-1 increases its sensitivity to in vitro lysis and reduces its in vivo tumorgenicity. In ICAM-1-negative murine neuroblastoma cells, ICAM-2 plays a primary role in cell-mediated lysis.This work was supported in part by the Children's Cancer Research Fund, the Minnesota Medical Foundation, the Viking Children's Fund and NIH grants PO1-CA-21737, NO1-AI-85002. E. K. is a recipient of the Irvine McQuarrie Research Scholar Award and B. R. B. a recipient of the Edward Mallinkrodt Foundation Scholar Award     

Cyclophilin A binds to AKT1 and facilitates the tumorigenicity of Epstein-Barr virus by mediating the activation of AKT/mTOR/NF-κB positive feedback loop

The AKT/mTOR and NF-κB signalings are crucial pathways activated in cancers including nasopharyngeal carcinoma (NPC), which is prevalent in southern China and closely related to Epstein-Barr virus (EBV) infection. How these master pathways are persistently activated in EBV-associated NPC remains to be investigated. Here we demonstrated that EBV-encoded latent membrane protein 1 (LMP1) promoted cyclophilin A (CYPA) expression through the activation of NF-κB. The depletion of CYPA suppressed cell proliferation and facilitated apoptosis. CYPA was able to bind to AKT1, thus activating AKT/mTOR/NF-κB signaling cascade. Moreover, the use of mTOR inhibitor, rapamycin, subverted the activation of the positive feedback loop, NF-κB/CYPA/AKT/mTOR. It is reasonable that LMP1 expression derived from initial viral infection is enough to assure the constant potentiation of AKT/mTOR and NF-κB signalings. This may partly explain the fact that EBV serves as a tumor-promoting factor with minimal expression of the viral oncoprotein LMP1 in malignancies. Our findings provide new insight into the understanding of causative role of EBV in tumorigenicity during latent infection.     

Autocrine stimulation by insulin-like growth factor I is involved in the growth, tumorigenicity and chemoresistance of human esophageal carcinoma cells

Insulin-like growth factor I (IGF-I) receptor (IGF-IR)-mediated signals are known to be involved in cell growth and transformation and prevention of apoptosis. In this study, we demonstrated the coexpression of IGF-I and IGF-IR in human esophageal carcinoma tissues. We also demonstrated the IGF-I autocrine system in esophageal carcinoma cell lines. Both the CE48T/VGH and CE81T/VGH cell lines showed proliferative responses to IGF-I stimulation. Autokinase activity of IGF-IR in these cells can be triggered by the exogenous addition of IGF-I. In addition, an IGF-I peptide antagonist, JB1, specifically inhibited ligand-induced receptor autophosphorylation in a dose-dependent manner. Under serum-free conditions, JB1 also reduced the degree of IGF-IR phosphorylation and cell numbers. Furthermore, the addition of JB1 decreased the number of CE81T/VGH colonies formed in methyl cellulose agar and the size and the incidence of tumors which grew in mice with severe combined immunodeficiency. These results imply that an IGF-I autocrine system in human esophageal carcinoma cells could stimulate tumor growth. Finally, we found that IGF-I prevented the apoptosis of CE81T/VGH cells induced by chemotherapeutic drugs, such as cisplatin, 5-fluorouracil and camptothecin. Thus, interruption of IGF-IR function may provide a way to retard tumor growth and increase the sensitivity of esophageal carcinoma to chemotherapy.     

高转移人肺癌细胞系DNA转移特性的研究

 用高转移肺癌细胞DNA转染NIH/3T3鼠细胞,获得的转化细胞在裸鼠体内表现不同的成瘤潜伏期,鉴定了整合到鼠细胞中入DNA序列,并得到一株在裸鼠体内有转移活性的转化细胞株。     

A novel lncRNA,Lnc-OC1, promotes ovarian cancer cell proliferation and migration by sponging miR-34a and miR-34c

Long non-coding RNAs (lncRNAs) have been reported to be of great importance in tumorigenesis and progression of a variety of cancers. However, the role of lncRNAs in ovarian cancer (OC) remains largely unknown. In the present study, we identified a novel lncRNA, LOC100288181 (named as Lnc-OC1), which acted as a key regulator in the development and progression of OC. The combined Gene Expression Omnibus (GEO) database analysis revealed that Lnc-OC1 was significantly upregulated in OC tissues and Kaplan-Meier survival analysis confirmed that high Lnc-OC1 expression was associated with poor prognosis of OC patients. Importantly, we also demonstrated that knockdown of Lnc-OC1 suppressed cell proliferation, colony formation, invasion and migration in vitro and inhibited tumorigenicity in vivo. Mechanistically, Lnc-OC1 repressed the expression of endogenous miR-34a and miR-34c as a sponge and vice versa. Moreover, rescue experiments demonstrated that the oncogenic function of Lnc-OC1 at least partially depended on suppressing miR-34a and miR-34c. In conclusion, our results suggest that the Lnc-OC1-miR-34a/34c axis may play a pivotal role in OC, and may serve as a potential diagnostic biomarker and a powerful therapeutic target for OC.     

反义RNA抑制人黑色素瘤细胞表面粘附分子CD44的表达及抑瘤效应

将细胞表面粘附分子ＣＤ４４Ｓ的ｃＤＮＡ反向插入到真核细胞表达载体ｐＭＡＭｎｅｏ－ＣＡＴ和ＭＭＴＶ－ＬＴＲ启动子下游,构成ＣＤ４４Ｓ的反义ＲＮＡ载体．将其用电击法导入ＣＤ４４＋的人黑色素瘤细胞系ＨＭＭ２３９,转录出的反义ＲＮＡ能不同程度地抑制ＨＭＭ２３９表面ＣＤ４４的表达．ＣＤ４４的表达被抑制后,瘤细胞与透明质酸的结合力下降,细胞的体外生长速率不受影响．将其接种裸鼠皮下,发现其致瘤性明显降低     

The loss of class II MHC antigen expression byras-transformed murine fibroblasts passaged as tumours correlates with increased tumorigenicity but is not mediated by T cells

Summary In several murine tumour systems, expression of class II major histocompatibility complex (MHC) antigens by tumour cells, either constitutive or inducible, correlates with reduced tumorigenicity as compared with equivalent class-II-negative cells, and CD4 phenotype T cells together with interferon (which induces the expression of class II) may be involved in the control of the proliferation of class-II-expressing tumours. This implies a potential T-cell-mediated selection pressure against class II expression. To test this possibility, we have repeatedly passaged as tumours in euthymic, syngeneic miceras-transformed murine fibroblast lines, which are class-II-inducible, to determine whether class-II-non-inducible variants are selected. We examined the expression of both class I and class II antigen in tumour cells re-established in vitro. It was found that the inducibility of class II, but not class I, expression rapidly diminished, correlating with augmented tumorigenicity. However, this loss of class II inducibility occurred in athymic as well as euthymic mice. Therefore, despite the fact that the tumorigenicity of these lines is augmented in euthymic mice depleted of CD4 T cells or interferon , we found no evidence of T-cell-mediated selection against class II expression. The loss of class II expression observed must be due to mechanisms other than immune selection. The possibility that this might result from other soluble factors modulating the response to interferon in vivo is discussed.     

Suppression of laminin-5 expression leads to increased motility, tumorigenicity, and invasion

Laminin-5 (Ln-5) is expressed in several human carcinomas and hypothesized to contribute to tumor invasion. To understand the role of Ln-5 in human cancers, we stably delivered small interfering RNAs (siRNAs) directed against the Ln-5 gamma2 chain into JHU-022-SCC cells (022), a non-invasive oral squamous cell carcinoma (OSCC) cell line which secretes Ln-5. Lysates from gamma2 siRNA cells (022-sigamma2) had nearly undetectable levels of the gamma2 chain while the alpha3 and beta3 subunits of Ln-5 remained unchanged compared to parental and control. In conditioned medium from 022-sigamma2 cells, the gamma2 chain and the Ln-5 heterotrimer were barely detectable, similar to an invasive OSCC cell line. Conditioned medium from 022-sigamma2 cells contained less alpha3 and beta3 subunits than both parental and control. Although the proliferation and adhesive properties of the 022-sigamma2 cells remained similar to parental and control cells, 022-sigamma2 cells showed increased detachment and a fibroblastic morphology similar to invasive cells. Moreover, migration, in vitro invasion, and in vivo tumorigenicity were enhanced in 022-sigamma2 cells. Our results suggest that the Ln-5 gamma2 chain regulates the secretion of the alpha3 and beta3 subunits. More importantly, suppression of Ln-5 results in a phenotype that is representative of invasive tumor cells.