IBYME   02675
INSTITUTO DE BIOLOGIA Y MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Immunotherapy against breast cancer based on Stat3 blockade
Autor/es:
DE MARTINO M, MERCOGLIANO MF,TKACH M, VENTURUTTI L, ELIZALDE PV, SCHILLACI R.
Reunión:
Congreso; AACR 106th Annual Meeting 2015; 2015
Resumen:
The signal transducer and activator of
transcription 3 (Stat3) is constitutively active in breast cancer (BC) and
contributes to malignant transformation by promoting cell cycle progression,
inhibiting apoptosis and mediating tumor immune evasion. Stat3 inhibition
induces expression of proinflammatory cytokines and chemokines. On the other
hand, it has been shown that oncogene inactivation induces cellular senescence
and the secretion of senescence-associated secretome (SAS) in diverse tumor
types. We recently described that Stat3 blockade leads to a senescence program
in murine BC cells, which is accompanied by the secretion of proinflammatory
cytokines. In addition, we demonstrated that immunization of mice with
syngeneic Stat3 blocked BC cells induces an antitumoral immune response that
involves the participation of CD4+ Th cells and cytotoxic NK cells. In this
study our objectives were to study whether immunization with supernatants (SN)
produced by Stat3-blocked cells induces an antitumor immune response and to
explore the contribution of senescence phenotype in this response. For that
purpose we used BC models of ErbB-2-positive, JIMT-1 and KPL-4 cells (human)
and C4HD cells (murine), and of triple negative, MDA-MB231 cells (human) and
4T1 cell (murine). Knockdown of Stat3 with siRNA in these cells, induced
senescence (assessed by acidic β-galactosidase
staining). In human BC cells the senescent phenotype was accompanied by
up-regulation of p21cip1 and downregulation of Rb expressions. In mouse BC
cells we observed an increased expression of p16ink4a. In addition,
simultaneous transfection with siRNAs targeting Stat3 and p16ink4a reverted the
senescent phenotype. Then, we used a pre-clinical model in which we embedded
the SN of C4HD cells in a slow-delivery depot as an adjuvant of a cellular
immunotherapy. We immunized the animals with irradiated C4HD cells together
with a depot containing lyophilized SN of C4HD cells transfected in vitro
either with Stat3 siRNA (senescent) and Stat3 and p16ink4a siRNA (non-senescent),
or a control siRNA. After 3 immunizations, with 15 d of interval between them,
animals were challenged with C4HD tumor and tumor growth was monitored for 40
d. We observed that immunization with SN of cells with Stat3 siRNA decreased
tumor growth vs. control siRNA group. Interestingly, there was no difference
between tumor growth of animals immunized with SN of cells with Stat3 siRNA vs
Stat3 and p16ink4a siRNA. We observed in these two groups greater cytotoxic
activity of NK cells and an increase in the number of memory CD4+ T cells vs.
control.
These results suggest that Stat3 blockade drives a senescence program also in
human BC cells. The secretome of Stat3-blocked BC cells is an effective
adjuvant and could be formulated for immunotherapies independently of the SAS.
Defining the protein, peptide, cytokine, chemokine composition of this
supernatant opens up new avenues for immunotherapy in cancer patients.