Download Tipo de Comunicación: Comunicación Oral Simposio

Tipo de Comunicación:
Comunicación Oral
Simposio:
BIOMEDICINA, MEDICINA REGENERATIVA Y BIOMATERIALES
Título:
Engineering Salmonella as intracellular factory for effective killing of tumour cells
Autores:
Camacho Fernández E.M., Mesa Pereira B., Medina Morillas C., Flores Díaz A., Santero
Santurino E.
Centro de Trabajo:
CABD-Universidad Pablo De Olavide
Email:
[email protected]
Palabras Clave:
Tumour; Salmonella; delivery; Cp53; apoptosis; autolysis
Comunicación:
Background
The use of bacteria as factories for therapeutic proteins production in vivo is a promising
biomedical tool. Especially, live bacteria therapy is viewed as an alternative in cancer
treatment due to the capacity of several species to target and penetrate tumours.
Salmonella, in addition to having this capability, can be easily engineered to produce
antitumor molecules from inside the tumour, thus increasing the specificity and efficiency of
the treatments. One of the main limitations of this approach is the efficient release of
therapeutic molecules from intratumoral bacteria.
Results
In this study we have developed an inducible autolysis system that, in response to
anhydrotetracycline, lysates intracellular bacteria releasing their content. The lysis operon of
lambda phage was cloned under the Ptet promoter control into modified vectors and
introduced into Salmonella strains. The system was combined with a salicylate cascade
system that allows efficient production of the therapeutic molecules in response to aspirin.
This strain was further modified introducing a sifA mutation into the bacterial chromosome
that liberates bacteria from the vacuoles to a cytosolic location. Our results show that almost
100% of the bacterial population die after lysis induction both in bacterial and cellular
cultures. This bacterial lysis correlates with the release of bacterial content into the growth
media or cytosol, respectively. We have used our engineered strain for the intracellular
production and delivery of Cp53 peptide. The results indicate that when production and
release of this peptide are suitably separated in the time, the Cp53 peptide produced
intracellularly induces cell death.
Conclusion
The combination of three elements – namely, an aspirin inducible system for therapeutic
molecules production, an anhydrotetracycline inducible system for bacterial content release
and a sifA mutation – makes our strain a putative powerful instrument in cancer treatment.
The engineered strain is able to produce and release cytotoxic peptides while it proliferates
inside tumour cells, thus inducing host cell death. Our results show that temporal separation
of protein production from protein release is essential to kill efficiently tumour cells. The
combined system is a step further in the engineering of the perfect bacteria for cancer
therapy.