Antitumor activity of DNA vaccines based on the human papillomavirus-16 E7 protein genetically fused to a plant virus coat protein.

DNA vaccination represents an attractive strategy for cancer immunotherapy combining vaccine stability, cost-effectiveness, and safety. However, a major problem of genetic vaccination is the limited potency, due to intrinsic lack of amplifying and spreading abilities in vivo and to the suboptimal intracellular processing/presentation of tumor antigens. We explored the therapeutic antitumor potency of DNA vaccines based on a mutated, nontransforming form of the E7 gene (E7GGG gene) of human papilloma virus 16 (HPV-16) fused, with or without a linker, to the potato virus X (PVX) coat protein sequence (PVX-CP). Transfection of mammalian cells demonstrated expression of the E7GGG protein, while the fusion proteins were detected only in the presence of proteasome inhibitors, suggesting increased instability and faster degradation via the proteasome. The DNA fusion vaccines, administered intramuscularly to C57BL/6 mice after challenging with a tumorigenic dose of E7-expressing TC-1 cells, inhibited the growth of tumors in vivo better than the E7GGG gene alone and induced both humoral and cell-mediated immune responses. Therefore, fusion of the HPV-16 E7GGG gene with a plant virus coat protein gene might be a valid strategy to induce antitumor immunity in a safe setting by a novel genetic vaccine targeting cervical carcinoma.

Plant-derived human papillomavirus 16 E7 oncoprotein induces immune response and specific tumor protection.

Vaccine strategies for treatment of human papillomavirus-induced cervical cancer are based on either the recombinant E7 fusion oncoprotein or E7 CTL peptides. The therapeutic potential of the E7-based vaccine depends on the use of different adjuvants. In this study, we describe for the first time the expression of the human papillomavirus 16 E7 protein in Nicotiana benthamiana plant using a potato virus X-derived vector. C57BL/6 mice immunized with E7-containing crude foliar extracts developed both humoral and cell-mediated immune responses and were protected from tumor development after challenge with the E7-expressing C3 tumoral cell line. Our data support the possibility of producing a cost-effective anticancer vaccine in plant with intrinsic adjuvant-like properties.

Growth inhibition of cervix carcinoma cells in vivo by endothelin A receptor blockade.

In human papillomavirus (HPV)-positive cervical cancer cells, the endothelin A receptor (ET(A)R) mediates an endothelin-1-induced mitogenic effect, thus representing a relevant target for antitumor therapy. Here, we describe the complete inhibition of human cervix carcinoma growth by blocking the ET(A)R. In nude mice, the ET(A)R-selective antagonist atrasentan inhibits the growth and the neoangiogenesis of cervical carcinoma cell xenografts. Two cycles of treatment completely revert tumor growth. Atrasentan displays additive effects when administered in combination with the cytotoxic drug paclitaxel. These results demonstrate that by inhibiting cell proliferation and angiogenesis, this small molecule may help to control cervical cancer by either monotherapy or combination therapy.

Formation of GaP/Si(100) Heterointerfaces in the Presence of Inherent Reactor Residuals.

Adequate silicon preparation is a prerequisite for defect-free III-V growth on Si. We transfer the silicon processing from clean to GaP containing metalorganic vapor phase epitaxy reactors, where we monitor the entire process in situ with reflection anisotropy spectroscopy and analyze the chemical composition of the surface with X-ray photoelectron spectroscopy. Beyond a certain submonolayer threshold value of (Ga,P) residuals found on the Si(100) surface, GaP grows with an inverted majority sublattice. Analogously to III-V growth on two-domain substrates, the coexistence of Si-Ga and Si-P interfacial bonds at terraces of the same type causes antiphase disorder in GaP epilayers.

Targeting endothelin receptor type A in human cervical carcinoma cells.

Human papilloma viruses are associated with cervical cancer and enhance signal transduction of growth factors. In human papilloma virus-positive cervical cancer cells, the endothelin-A receptor mediates the endothelin-1-induced mitogenic effect, and sustains the basal growth rate of unstimulated cervical tumor cells. In this study, the action of a specific endothelin-A receptor antagonist (atrasentan) and a truly 'balanced' endothelin-A/endothelin-B antagonist (A-182086), was analysed in the human cervical carcinoma cells, CaSki and C33A. CaSki cells are human papilloma virus-16-positive, produce endothelin-1 and possess endothelin-A and endothelin-B receptors, whereas the C33A line is human papilloma virus-negative, does not secrete endothelin-1 and has only endothelin-B receptors. In human papilloma virus-positive cancer cells both antagonists caused a similar drastic reduction in BrdU incorporation and in the growth rate. These data clearly demonstrate that A-182086 and atrasentan show similar potency and also indicate that blocking of the endothelin-B receptor by A- 182086 does not increase the anti-proliferative effect. This finding suggests that the endothelin-B receptor does not participate in the growth control of CaSki cells. Results from C33A cells reinforce this previous conclusion as both compounds are ineffective in altering the BrdU uptake of these cells in basal and endothelin-1 stimulated conditions. In conclusion, targeting the endothelin-A receptor, but not the endothelin-B receptor, may be a valid tool in the therapy of cervical carcinoma.

A prime/boost strategy by DNA/fowlpox recombinants expressing a mutant E7 protein for the immunotherapy of HPV-associated cancers.

Development of effective therapeutic vaccines against human papilloma virus (HPV) infections remains a priority, considering the high number of new cases of cervical cancer each year by high-risk HPVs, in particular by HPV-16. Vaccines expressing the E7 oncoprotein, which is detectable in all HPV-positive pre-cancerous and cancer cells, might clear already established tumors and support the treatment of HPV-related lesions. In this study, DNA or fowlpox virus recombinants expressing the harmless variant E7GGG of the HPV-16 E7 oncoprotein (DNA(E7GGG) and FP(E7GGG)) were generated. Two immunization regimens were tested in a pre-clinical mouse model by homologous (FP/FP) or heterologous (DNA/FP) prime-boost protocols to evaluate the immune response and therapeutic efficacy of the proposed HPV-16 vaccine. Low levels of anti-E7-specific antibodies were elicited after immunization, and in vivo experiments resulted in a higher number of tumor-free mice after the heterologous immunization. These results establish a preliminary indication for therapy of HPV-related tumors by the combined use of DNA and avipox recombinants, which might represent safer immunogens than vaccinia-based vaccines.

[First occurrence of Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae) preying on defoliating caterpillars of oil palm in the State of Pará, Brazil]. / Primeira ocorrência de Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae) predando lagartas desfolhadoras do dendezeiro no estado do Pará

The oil palm Elaeis guineensis is usually attacked by pests, particularly, defoliating caterpillars. Between 2004 and 2006 a stinkbug predator (Asopinae) was registered preying on caterpillars of Brassolis sophorae L., Opsiphanes invirae Hübner (Lepidoptera: Nymphalidae) and Sibine spp. (Lepidoptera: Limacodidae), reducing their populations in commercial oil palm plantations in the State of Pará, Brazil. Specimens of the natural enemy were collected, mounted, and identified as Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae), corresponding to the first report of the occurrence of this stinkbug attacking defoliating caterpillars of oil palm in Brazil.

Anti-cancer activity of plant-produced HPV16 E7 vaccine.

The E7 oncoprotein from Human Papilloma Virus (HPV) is an attractive candidate for anti-cancer vaccine development. In this study, we engineered HPV16 E7 coding sequence (wild type or mutagenized sequence, E7GGG) as fusions to beta-1,3-1,4-glucanase (LicKM) of Clostridium thermocellum and produced in Nicotiana benthamiana plants using a transient expression system. Target antigens were purified and evaluated in mice for their potential as prophylactic and therapeutic vaccine candidates. Both fusion proteins induced E7-specific IgG and cytotoxic T-cell responses and protected mice against challenge with E7-expressing tumor cells. Furthermore, when administered after challenge, these plant-produced antigens prevented tumor development.

Primeira ocorrência de Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae) predando lagartas desfolhadoras do dendezeiro no estado do Pará / First occurrence of Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae) preying on defoliating caterpillars of oil palm in the state of Pará, Brazil

The oil palm Elaeis guineensis is usually attacked by pests, particularly, defoliating caterpillars. Between 2004 and 2006 a stinkbug predator (Asopinae) was registered preying on caterpillars of Brassolis sophorae L., Opsiphanes invirae Hübner (Lepidoptera: Nymphalidae) and Sibine spp. (Lepidoptera: Limacodidae), reducing their populations in commercial oil palm plantations in the State of Pará, Brazil. Specimens of the natural enemy were collected, mounted, and identified as Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae), corresponding to the first report of the occurrence of this stinkbug attacking defoliating caterpillars of oil palm in Brazil.

Endothelin receptor blockade inhibits the growth of human papillomavirus-associated cervical carcinoma.

Human papillomaviruses (HPVs) are associated with cervical cancer and interact with growth factors that may enhance malignant transformation of cervical carcinoma cells. Endothelin-1 (ET-1) is released from HPV-transfected keratinocytes and induces increased growth response in these cell lines in comparison with normal cells. HPV-positive cancer cells secrete ET-1 and express mRNA for ET-1 and its receptors, whereas HPV-negative carcinoma cell lines express only the ET(B) receptor (ET(B)R) mRNA and do not secrete ET-1. In HPV-positive cancer cells, ET(A)R mediates the ET-1-induced mitogenic effect and sustains the basal growth rate of unstimulated cervical tumour cells. Therefore, ET-1 may be involved in the neoplastic growth of HPV-associated cervical carcinoma, where the increased ET-1 autocrine loop can be targeted for antitumour therapy. In the present work, the action of specific antagonists of ET(A)R (BQ-123 and ABT-627), was analysed in CaSki and C33A cells that are derived from human cervical carcinoma. CaSki cells are HPV-16-positive, produce ET-1 and possess ET(A)R and ET(B)R, whereas the C33A line is HPV-negative, does not secrete ET-1 and has no ET(A)R. In HPV-positive cancer cells ABT-627 strongly inhibited the proliferation induced by ET-1 and substantially reduced the basal growth rate of unstimulated cervical tumour cells, whereas the ET(B)R antagonist had no effect. These results demonstrate that ET-1 participates in the progression of neoplastic growth in HPV-associated carcinoma, in which ET(A)R expression is increased and could be targeted for antitumour therapy. In conclusion, an ET-1 autocrine loop is involved in tumour cell proliferation via ET(A)R, and ABT-627 is effective in controlling proliferation of cervical carcinoma cells.