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Immunotherapy of HPV-associated cancer: DNA/plant-derived vaccines and new orthotopic mouse models.

Venuti A, Curzio G, Mariani L, Paolini F - Cancer Immunol. Immunother. (2015)

Bottom Line: Under the optimistic assumption of high-prophylactic HPV vaccine coverage, a significant reduction of cancer incidence can only be expected after decades.Thus, immune therapeutic strategies are needed for persistently infected individuals who do not benefit from the prophylactic vaccines.In particular, the head/neck orthotopic model appears to be very promising for studies combining chemo-radio-immune therapy that seems to be very effective in patients.

View Article: PubMed Central - PubMed

Affiliation: HPV-UNIT, Laboratory of Virology, Regina Elena National Cancer Institute, Via E. Chianesi 53, 00144, Rome, Italy, venuti@ifo.it.

ABSTRACT
Under the optimistic assumption of high-prophylactic HPV vaccine coverage, a significant reduction of cancer incidence can only be expected after decades. Thus, immune therapeutic strategies are needed for persistently infected individuals who do not benefit from the prophylactic vaccines. However, the therapeutic strategies inducing immunity to the E6 and/or E7 oncoprotein of HPV16 are more effective for curing HPV-expressing tumours in animal models than for treating human cancers. New strategies/technologies have been developed to improve these therapeutic vaccines. Our studies focussed on preparing therapeutic vaccines with low-cost technologies by DNA preparation fused to either plant-virus or plant-toxin genes, such as saporin, and by plant-produced antigens. In particular, plant-derived antigens possess an intrinsic adjuvant activity that makes these preparations especially attractive for future development. Additionally, discrepancy in vaccine effectiveness between animals and humans may be due to non-orthotopic localization of animal models. Orthotopic transplantation leads to tumours giving a more accurate representation of the parent tumour. Since HPV can cause cancer in two main localizations, anogenital and oropharynx area, we developed two orthotopic tumour mouse models in these two sites. Both models are bioluminescent in order to follow up the tumour growth by imaging and are induced by cell injection without the need to intervene surgically. These models were utilized for immunotherapies with genetic or plant-derived therapeutic vaccines. In particular, the head/neck orthotopic model appears to be very promising for studies combining chemo-radio-immune therapy that seems to be very effective in patients.

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Head and neck mouse model of HPV-associated cancer: intratumoural therapy. a The presence of bioluminescent metastases in explanted organs of mice carrying the AT-84 E7 Luc tumours. Bioluminescence was measured by imaging system after addition of D-luciferin. b Time-course of luciferase expression in AT-84 E7 Luc tumour and metastasis. Bioluminescence was calculated as photons/sec/cm2/sr, and data are mean ± SD of 5 animals. c Representative intratumoural treatment. Treatment with indicated DNA vaccine preparations was performed by a prime dose (100 µg) i.m. 3 days after AT-84 E7 Luc injection in the mouth pavement followed 6 days later by DNA vaccine inoculation (100 µg) within the tumour. Tumour growth was monitored at the indicated time intervals post-challenge. Bioluminescence was measured 15 min after intraperitoneal injection of D-luciferin by imaging system and quantified as photons/s/cm2/sr in a colour scale. pVax, empty vector; pVax E7SAP, fusion between HPV16 E7GGG and mutated Saporin; pVax E7GGG, HPV16 E7GGG gene
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Fig2: Head and neck mouse model of HPV-associated cancer: intratumoural therapy. a The presence of bioluminescent metastases in explanted organs of mice carrying the AT-84 E7 Luc tumours. Bioluminescence was measured by imaging system after addition of D-luciferin. b Time-course of luciferase expression in AT-84 E7 Luc tumour and metastasis. Bioluminescence was calculated as photons/sec/cm2/sr, and data are mean ± SD of 5 animals. c Representative intratumoural treatment. Treatment with indicated DNA vaccine preparations was performed by a prime dose (100 µg) i.m. 3 days after AT-84 E7 Luc injection in the mouth pavement followed 6 days later by DNA vaccine inoculation (100 µg) within the tumour. Tumour growth was monitored at the indicated time intervals post-challenge. Bioluminescence was measured 15 min after intraperitoneal injection of D-luciferin by imaging system and quantified as photons/s/cm2/sr in a colour scale. pVax, empty vector; pVax E7SAP, fusion between HPV16 E7GGG and mutated Saporin; pVax E7GGG, HPV16 E7GGG gene

Mentions: When considering all these aspects, this animal model is a valid tool for testing novel therapies. The newly developed AT-84 E7 model maintains all the properties of the parental cells with addition of HPV16 E7 oncoprotein expression. Once implanted, the stable expression of this oncogene is maintained, not only within the tumour, but also in distant metastases (Fig. 2a, b) [55]. This result further supports the utility of this orthotopic mouse model for HPV-related human oral cancer, as E7 expression is always maintained in oral human cancer and metastases. Indeed, E7 protein expression levels are similar to those observed in naturally occurring HPV tumours. The low expression level of E7 in AT-84 E7 tumours compared with other non-orthotopic models (i.e. C3 and TC-1) may provide a more realistic picture of the natural condition of HPV-related tumours. Indeed, the great difference between the high expression levels of E7 in C3 and TC-1 models and the low levels in human cancers is a plausible explanation why several immunotherapies proven efficacious in C3 and TC-1 models failed to be effective in humans. Thus, AT-84 E7 cells may represent the best oral model to test the feasibility of therapeutic vaccination. This model was further improved by making AT-84 E7 bioluminescent by Lenti-Luc infection, allowing less invasive and more accurate follow-up [55].Fig. 2


Immunotherapy of HPV-associated cancer: DNA/plant-derived vaccines and new orthotopic mouse models.

Venuti A, Curzio G, Mariani L, Paolini F - Cancer Immunol. Immunother. (2015)

Head and neck mouse model of HPV-associated cancer: intratumoural therapy. a The presence of bioluminescent metastases in explanted organs of mice carrying the AT-84 E7 Luc tumours. Bioluminescence was measured by imaging system after addition of D-luciferin. b Time-course of luciferase expression in AT-84 E7 Luc tumour and metastasis. Bioluminescence was calculated as photons/sec/cm2/sr, and data are mean ± SD of 5 animals. c Representative intratumoural treatment. Treatment with indicated DNA vaccine preparations was performed by a prime dose (100 µg) i.m. 3 days after AT-84 E7 Luc injection in the mouth pavement followed 6 days later by DNA vaccine inoculation (100 µg) within the tumour. Tumour growth was monitored at the indicated time intervals post-challenge. Bioluminescence was measured 15 min after intraperitoneal injection of D-luciferin by imaging system and quantified as photons/s/cm2/sr in a colour scale. pVax, empty vector; pVax E7SAP, fusion between HPV16 E7GGG and mutated Saporin; pVax E7GGG, HPV16 E7GGG gene
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4554738&req=5

Fig2: Head and neck mouse model of HPV-associated cancer: intratumoural therapy. a The presence of bioluminescent metastases in explanted organs of mice carrying the AT-84 E7 Luc tumours. Bioluminescence was measured by imaging system after addition of D-luciferin. b Time-course of luciferase expression in AT-84 E7 Luc tumour and metastasis. Bioluminescence was calculated as photons/sec/cm2/sr, and data are mean ± SD of 5 animals. c Representative intratumoural treatment. Treatment with indicated DNA vaccine preparations was performed by a prime dose (100 µg) i.m. 3 days after AT-84 E7 Luc injection in the mouth pavement followed 6 days later by DNA vaccine inoculation (100 µg) within the tumour. Tumour growth was monitored at the indicated time intervals post-challenge. Bioluminescence was measured 15 min after intraperitoneal injection of D-luciferin by imaging system and quantified as photons/s/cm2/sr in a colour scale. pVax, empty vector; pVax E7SAP, fusion between HPV16 E7GGG and mutated Saporin; pVax E7GGG, HPV16 E7GGG gene
Mentions: When considering all these aspects, this animal model is a valid tool for testing novel therapies. The newly developed AT-84 E7 model maintains all the properties of the parental cells with addition of HPV16 E7 oncoprotein expression. Once implanted, the stable expression of this oncogene is maintained, not only within the tumour, but also in distant metastases (Fig. 2a, b) [55]. This result further supports the utility of this orthotopic mouse model for HPV-related human oral cancer, as E7 expression is always maintained in oral human cancer and metastases. Indeed, E7 protein expression levels are similar to those observed in naturally occurring HPV tumours. The low expression level of E7 in AT-84 E7 tumours compared with other non-orthotopic models (i.e. C3 and TC-1) may provide a more realistic picture of the natural condition of HPV-related tumours. Indeed, the great difference between the high expression levels of E7 in C3 and TC-1 models and the low levels in human cancers is a plausible explanation why several immunotherapies proven efficacious in C3 and TC-1 models failed to be effective in humans. Thus, AT-84 E7 cells may represent the best oral model to test the feasibility of therapeutic vaccination. This model was further improved by making AT-84 E7 bioluminescent by Lenti-Luc infection, allowing less invasive and more accurate follow-up [55].Fig. 2

Bottom Line: Under the optimistic assumption of high-prophylactic HPV vaccine coverage, a significant reduction of cancer incidence can only be expected after decades.Thus, immune therapeutic strategies are needed for persistently infected individuals who do not benefit from the prophylactic vaccines.In particular, the head/neck orthotopic model appears to be very promising for studies combining chemo-radio-immune therapy that seems to be very effective in patients.

View Article: PubMed Central - PubMed

Affiliation: HPV-UNIT, Laboratory of Virology, Regina Elena National Cancer Institute, Via E. Chianesi 53, 00144, Rome, Italy, venuti@ifo.it.

ABSTRACT
Under the optimistic assumption of high-prophylactic HPV vaccine coverage, a significant reduction of cancer incidence can only be expected after decades. Thus, immune therapeutic strategies are needed for persistently infected individuals who do not benefit from the prophylactic vaccines. However, the therapeutic strategies inducing immunity to the E6 and/or E7 oncoprotein of HPV16 are more effective for curing HPV-expressing tumours in animal models than for treating human cancers. New strategies/technologies have been developed to improve these therapeutic vaccines. Our studies focussed on preparing therapeutic vaccines with low-cost technologies by DNA preparation fused to either plant-virus or plant-toxin genes, such as saporin, and by plant-produced antigens. In particular, plant-derived antigens possess an intrinsic adjuvant activity that makes these preparations especially attractive for future development. Additionally, discrepancy in vaccine effectiveness between animals and humans may be due to non-orthotopic localization of animal models. Orthotopic transplantation leads to tumours giving a more accurate representation of the parent tumour. Since HPV can cause cancer in two main localizations, anogenital and oropharynx area, we developed two orthotopic tumour mouse models in these two sites. Both models are bioluminescent in order to follow up the tumour growth by imaging and are induced by cell injection without the need to intervene surgically. These models were utilized for immunotherapies with genetic or plant-derived therapeutic vaccines. In particular, the head/neck orthotopic model appears to be very promising for studies combining chemo-radio-immune therapy that seems to be very effective in patients.

Show MeSH
Related in: MedlinePlus