Wen-Fang Cheng

Tumor-specific immunity and antiangiogenesis generated by a DNA vaccine encoding calreticulin linked to a tumor antigen.

Antigen-specific cancer immunotherapy and antiangiogenesis have emerged as two attractive strategies for cancer treatment. An innovative approach that combines both mechanisms will likely generate the most potent antitumor effect. We tested this approach using calreticulin (CRT), which has demonstrated the ability to enhance MHC class I presentation and exhibit an antiangiogenic effect. We explored the linkage of CRT to a model tumor antigen, human papilloma virus type-16 (HPV-16) E7, for the development of a DNA vaccine. We found that C57BL/6 mice vaccinated intradermally with CRT/E7 DNA exhibited a dramatic increase in E7-specific CD8(+) T cell precursors and an impressive antitumor effect against E7-expressing tumors compared with mice vaccinated with wild-type E7 DNA or CRT DNA. Vaccination of CD4/CD8 double-depleted C57BL/6 mice and immunocompromised (BALB/c nu/nu) mice with CRT/E7 DNA or CRT DNA generated significant reduction of lung tumor nodules compared with wild-type E7 DNA, suggesting that antiangiogenesis may have contributed to the antitumor effect. Examination of microvessel density in lung tumor nodules and an in vivo angiogenesis assay further confirmed the antiangiogenic effect generated by CRT/E7 and CRT. Thus, cancer therapy using CRT linked to a tumor antigen holds promise for treating tumors by combining antigen-specific immunotherapy and antiangiogenesis.

Improving Vaccine Potency Through Intercellular Spreading and Enhanced MHC Class I Presentation of Antigen

The potency of naked DNA vaccines is limited by their inability to amplify and spread in vivo. VP22, a HSV-1 protein, has demonstrated the remarkable property of intercellular transport and may thus provide a unique approach for enhancing vaccine potency. Therefore, we created a novel fusion of VP22 with a model Ag, human papillomavirus type 16 E7, in a DNA vaccine that generated enhanced spreading and MHC class I presentation of Ag. These properties led to a dramatic increase in the number of E7-specific CD8+ T cell precursors in vaccinated mice (around 50-fold) and converted a less effective DNA vaccine into one with significant potency against E7-expressing tumors. In comparison, nonspreading VP221–267 mutants failed to enhance vaccine potency. Our data indicated that the potency of DNA vaccines may be dramatically improved through intercellular spreading and enhanced MHC class I presentation of Ag.

The anti-apoptotic role of interleukin-6 in human cervical cancer is mediated by up-regulation of Mcl-1 through a PI 3-K/Akt pathway

Interleukin-6 (IL-6), a multifunctional cytokine, has recently been implicated in human cervical cancer, though the mechanism remains elusive. This study demonstrates that the anti-apoptotic protein Mcl-1 and IL-6 was concomitantly expressed in human cervical cancer tissues and cell lines, but not in normal cervix tissues. Upon IL-6 treatment, Mcl-1, but not other Bcl-2 family members, was rapidly up-regulated peaking at 4–8 h in human cervical cancer C33A cells. Supporting this observation, using anti-IL-6 or anti-IL-6 receptor antibody to interrupt the IL-6 autocrine loop in SiHa cells significantly reduced cellular level of Mcl-1. This study hypothesizes that the expression of Mcl-1 in cervical cancer cells is regulated by IL-6. The matter of which signaling pathways transduced by IL-6 is responsible for the Mcl-1 up-regulation is further investigated herein. Blocking the STAT3 or MAPK pathway with dominant-negative mutant STAT3F or the MEK inhibitor PD98059 failed to inhibit IL-6-mediated Mcl-1 expression. Meanwhile, the IL-6-induced Mcl-1 up-regulation was effectively abolished by treatment with PI 3-K inhibitors, LY294002. Additionally, overexpression of dominant-negative (dn) Akt in C33A cells could inhibit the IL-6-induced increase of Mcl-1. Finally, overexpression of IL-6 in C33A cells caused a markable resistance to apoptosis induced by doxorubicin or cisplatin. Transient transfection of IL-6-overexpressed cells with a mcl-1 antisense vector, leading to the attenuation of their apoptosis-resistant activity. In conclusion, the data herein suggest that IL-6 regulated the mcl-1 expression via a PI 3-K/Akt-dependent pathway that may facilitate the oncogenesis of human cervical cancer by modulating the apoptosis threshold.

Enhancement of Sindbis Virus Self-Replicating RNA Vaccine Potency by Linkage of Herpes Simplex Virus Type 1 VP22 Protein to Antigen

ABSTRACT Recently, self-replicating and self-limiting RNA vaccines (RNA replicons) have emerged as an important form of nucleic acid vaccines. Self-replicating RNA eventually causes lysis of transfected cells and does not raise the concern associated with naked DNA vaccines of integration into the host genome. This is particularly important for development of vaccines targeting proteins that are potentially oncogenic. However, the potency of RNA replicons is significantly limited by their lack of intrinsic ability to spread in vivo. The herpes simplex virus type 1 protein VP22 has demonstrated the remarkable property of intercellular transport and provides the opportunity to enhance RNA replicon vaccine potency. We therefore created a novel fusion of VP22 with a model tumor antigen, human papillomavirus type 16 E7, in a Sindbis virus RNA replicon vector. The linkage of VP22 with E7 resulted in a significant enhancement of E7-specific CD8+ T-cell activities in vaccinated mice and converted a less effective RNA replicon vaccine into one with significant potency against E7-expressing tumors. These results indicate that fusion of VP22 to an antigen gene may greatly enhance the potency of RNA replicon vaccines.

Enhancement of Sindbis Virus Self-Replicating RNA Vaccine Potency by Linkage of Mycobacterium tuberculosis Heat Shock Protein 70 Gene to an Antigen Gene

Recently, self-replicating RNA vaccines (RNA replicons) have emerged as an effective strategy for nucleic acid vaccine development. Unlike naked DNA vaccines, RNA replicons eventually cause lysis of transfected cells and therefore do not raise the concern of integration into the host genome. We evaluated the effect of linking human papillomavirus type 16 E7 as a model Ag to Mycobacterium tuberculosis heat shock protein 70 (HSP70) on the potency of Ag-specific immunity generated by a Sindbis virus self-replicating RNA vector, SINrep5. Our results indicated that this RNA replicon vaccine containing an E7/HSP70 fusion gene generated significantly higher E7-specific T cell-mediated immune responses in vaccinated mice than did vaccines containing the wild-type E7 gene. Furthermore, our in vitro studies demonstrated that E7 Ag from E7/HSP70 RNA replicon-transfected cells can be processed by bone marrow-derived dendritic cells and presented more efficiently through the MHC class I pathway than can wild-type E7 RNA replicon-transfected cells. More importantly, the fusion of HSP70 to E7 converted a less effective vaccine into one with significant potency against E7-expressing tumors. This antitumor effect was dependent on NK cells and CD8+ T cells. These results indicated that fusion of HSP70 to an Ag gene may greatly enhance the potency of self-replicating RNA vaccines.

Cancer Immunotherapy Using Sindbis Virus Replicon Particles Encoding a VP22–Antigen Fusion

Alphavirus vectors have emerged as a strategy for the development of cancer vaccines and gene therapy applications. The availability of a new packaging cell line (PCL), which is capable of generating alphavirus replicon particles without contamination from replication-competent virus, has advanced the field of vaccine development. This replication-defective vaccine vector has potential advantages over naked nucleic acid vaccines, such as increased efficiency of gene delivery and large-scale production. We have developed a new strategy to enhance nucleic acid vaccine potency by linking VP22, a herpes simplex virus type 1 (HSV-1) tegument protein, to a model antigen. This strategy facilitated the spread of linked E7 antigen to neighboring cells. In this study, we created a recombinant Sindbis virus (SIN)-based replicon particle encoding VP22 linked to a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, using a stable SIN PCL. The linkage of VP22 to E7 in these SIN replicon particles resulted in a significant increase in the number of E7-specific CD8(+) T cell precursors and a strong antitumor effect against E7-expressing tumors in vaccinated C57BL/6 mice relative to wild-type E7 SIN replicon particles. Furthermore, a head-to-head comparison of VP22-E7-containing naked DNA, naked RNA replicons, or RNA replicon particle vaccines indicated that SINrep5-VP22/E7 replicon particles generated the most potent therapeutic antitumor effect. Our results indicated that the VP22 strategy used in the context of SIN replicon particles may facilitate the generation of a highly effective vaccine for widespread immunization.

Enhancement of suicidal DNA vaccine potency by linking Mycobacterium tuberculosis heat shock protein 70 to an antigen

Naked DNA vaccines represent an attractive approach for generating antigen-specific immunity because of their stability and simplicity of delivery. There are particular concerns with DNA vaccines however, such as potential integration into the host genome, cell transformation, and limited potency. The usage of DNA-based alphaviral RNA replicons (suicidal DNA vectors) may alleviate the concerns of integration or transformation since suicidal DNA vectors eventually cause lysis of transfected cells. To improve further the potency of suicidal DNA vaccines, we evaluated the effect of linking Mycobacterium tuberculosis heat shock protein 70 (Hsp70) to human papillomavirus type 16 (HPV-16) E7 as a model antigen on antigen-specific immunity generated by a DNA-based Semliki Forest virus (SFV) RNA vector, pSCA1. Our results indicated that this suicidal DNA vaccine containing E7/Hsp70 fusion genes generated significantly higher E7-specific T cell-mediated immune responses than vaccines containing the wild-type E7 gene in vaccinated mice. More importantly, this fusion converted a less effective vaccine into one with significant potency against established E7-expressing metastatic tumors. The antitumor effect was predominantly CD8-dependent. These results indicate that linkage of Hsp70 to the antigen may greatly enhance the potency of suicidal DNA vaccines.

Baicalein and baicalin are potent inhibitors of angiogenesis: Inhibition of endothelial cell proliferation, migration and differentiation

In recent studies, we have shown that baicalein and baicalin, 2 major flavonoids of Scutellaria baicalensis Georgi, exhibit anticancer activity against several cancers in vitro. In our present study, we assessed their potential as anti‐angiogenic agents in vivo employing chicken chorioallantoic membrane (CAM) assay and in vitro human umbilical vein endothelial cells (HUVECs) culture. When CAMs were treated with either baicalein or baicalin for 48 hr, the angiogenic response induced by basic fibroblast growth factor (bFGF) was markedly reduced in a dose‐dependent manner. Further characterization showed that both flavonoids exhibited dual antiproliferative (at low dose) and apoptogenic (at high dose) effects on HUVECs. In biochemical analysis, treatment of HUVECs with baicalein and baicalin for 24 hr resulted in a dose‐dependent decrease in the matrix metalloproteinase (MMP)‐2 activity. Moreover, the migration of endothelial cells and the differentiation of endothelial cells into branching networks of tubular structures in vitro were also inhibited by these 2 flavonoids in a dose‐dependent manner. Baicalein is more potent than baicalin in anti‐angiogenesis in vivo as well as in vitro. Taken together, the results of our study provide evidence that baicalein and baicalin possess an anti‐angiogenesis potential that is a previously unrecognized biologic activity.

Vascular endothelial growth factor and prognosis of cervical carcinoma

Objective To evaluate vascular endothelial growth factor (VEGF) as a marker for predicting lymph node metastasis and an independent prognostic factor of early-stage cervical carcinoma. Methods One hundred thirty-five women with stage IB–IIA cervical carcinoma had radical abdominal hysterectomies and pelvic lymph node dissections. Intratumoral cytosol VEGF concentrations were assayed with enzyme immunoassay. Histopathologic items and cytosol VEGF-influencing clinical outcomes were compared. Results Twenty-two women (16.3%) who had disease recurrence had higher levels of cytosol VEGF (1020 versus 112 pg/mg protein, P < .001) than those without recurrence. Using a cutoff value of 400 pg/mg protein resulted in best sensitivity of 75%, best specificity of 70%, positive predictive value of 41%, and negative predictive value of 92%. Only overexpressed cytosol VEGF (hazard ratio 6.44, P < .001) was an independent prognostic factor of disease-free survival. The overexpressed cytosol VEGF (hazard ratio 4.50, P = .021) and positive lymphovascular emboli (hazard ratio 4.11, P = .045) were independent prognostic factor of overall survival. Conclusion Cytosol VEGF might be a biomarker for the status of pelvic lymph nodes in early-stage cervical carcinoma and an independent prognostic indicator of its outcome.

Serous ovarian carcinoma patients with high alpha-folate receptor had reducing survival and cytotoxic chemo-response

The alpha‐folate receptor (α‐FR) is highly‐expressed in various non‐mucinous tumors of epithelial origin, including ovarian carcinoma. The aim of this study was to investigate the relationship between alpha‐folate receptor (α‐FR) and the clinico‐pathologic features and outcomes of serous ovarian carcinoma patients and the possible mechanism of α‐FR to chemo‐resistance. Therefore, semi‐quantitative reverse‐transcription polymerase chain reactions for α‐FR expression were performed in the 91 specimens of serous ovarian carcinomas. The expression of α‐FR in each ovarian cancer tissue specimen was defined as the ratio of density of α‐FR to density of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH). In vitro apoptotic experiments were tested in the original OVCAR‐3 tumor cells and various OVCAR‐3 α‐FR‐transfectants. Patients with an increased α‐FR expression level had poorer responses to chemotherapy (per α‐FR expression level increase: odds ratio (OR): 8.97 (95% confidence interval (CI): 1.40–57.36), p = 0.021). An increased α‐FR expression level was an independently poor prognostic factor for disease free interval (DFI) (per α‐FR expression level increase: hazard ratio (HR): 2.45 (95% CI: 1.16–5.18), p = 0.02) and had a negative impact on overall survival (OS) of these serous ovarian cancer patients (per α‐FR expression level increase: HR: 3.6 (95% CI: 0.93–13.29), p = 0.03) by multivariate analyses. α‐FR inhibited cytotoxic drug‐induced apoptosis in our in vitro apoptotic assays. α‐FR could induce chemo‐resistance via regulating the expression of apoptosis‐related molecules, Bcl‐2 and Bax. Therefore, α‐FR can be a potential biomarker for the prediction of chemotherapeutic responses and clinical prognosis. It also could be the target of ovarian cancer treatment.