Molecular mechanisms involved in the immunomodulation induced by LIF in cancer

Abstract

LIF is a pleiotropic cytokine that can act as an immunomodulatory factor in different biological processes, such as embryo implantation, organ transplantation tolerance and multiple sclerosis. Here, we have observed that in tumors expressing LIF, its blockade inhibits tumor growth, and that the anti-tumor effect of LIF neutralization is mediated by the polarization of tumor-associated myeloid cells (TAMCs). LIF sustains the expression of CCL22, MRC1 and CD163 in human healthy monocytes and in TAMCs from mouse syngeneic (non-small cell lung cancer, ovarian cancer and colorectal cancer) models, patient-derived xenograft models and organotypic cultures from glioblastoma. We show that LIF blockade down-regulates CCL22 secretion by TAMCs preventing regulatory T cell and inducing effector T and NK cell tumor infiltration, leading to an increase in tumor cell apoptosis and an anti-tumor response. A positive correlation between M2-like markers and LIF expression has been observed in glioblastoma patients, and high levels of these factors confer poor prognosis.

Moreover, we have studied one of the multiple mechanisms through which LIF could modulate the inhibition of effector T and NK cells: the regulation of PD-1/PDL1 axis. We have seen that after anti-LIF treatment of tumor-bearing mice, the expression of PDL1 decreases in tumor cells and in TAMCs. Furthermore, a positive correlation between PDL1 and LIF expression has been observed in glioblastoma patients, and both proteins also correlate with CD44 expression, a marker for cancer-initiating cell (CIC) population. High levels of these three factors confer poor prognosis.

Thus, we have found that LIF acts as an immune-suppressor in cancer recapitulating its normal function in other biological processes. LIF is a bridge between the innate and adaptive immune responses through the induction of CCL22 in TAMCs and subsequent regulation of regulatory and effector T and NK cells. Our results identify LIF as a promising immuno-oncology therapeutic target and establish the translational potential of anti-LIF agents.

LIF és una citoquina que actua corn un factor immunomodulador en diferents processos biologics, corn en la implantacio de l'embrio, en la tolerancia en trasplantaments d'argans i en I'esclerosi multiple. Hem observat que aquells tumors que expressen LIF, sofreixen una inhibicio del creixement tumoral en resposta al seu bloqueig. Aquest efecte esta mitjangat per la polaritzacio de les cel•ules mieloides associades al tumor (TAMCs) cap a un fenotip M2. LIF sustenta l'expressio de CCL22, MRC1 i CD163 en monacits alats de sang periferica de donants sans, en TAMCs de models singenics de ratolf (cancer de pulmo, ovari i colon), en models xenagrafts derivats de pacients i en cultius organotipics de glioblastoma. Demostrem que el bloqueig de LIF disminueix la secrecio de CCL22 de les TAMCs, prevenint la infiltracio tumoral de les cel•ules T reguladores (Tregs) i induint el reclutament de cel•ules T efectores (Teff) i de natural killer (NKs), el que comporta un augment en I'apoptosi de les cel•ules tumorals. Hem observat una correlacio positiva entre l'expressio de marcadors del fenotip M2 i LIF en pacients de glioblastoma. Alts nivells d'aquests factors confereixen un mal pronastic.

D'altra banda, hem estudiat un dels mecanismes mitjangant el qual LIF podria modular la inhibicio de les Teff i NKs: la regulacio PDL1. Hem observat que despres de tractar els ratolins amb l'anticas anti-LIF, l'expressio de PDL1 disminueix tant en les cel•ules tumorals corn en les TAMCs. A mes, hem trobat una correlacio positiva entre l'expressio de PDL1 i LIF en pacients amb glioblastoma, i ambdues protenes correlacionen amb CD44, un marcador d'una poblacio enriquida amb cel•ules iniciadores de tumor (CICs). Alts nivells d'aquests tres factors confereixen un mal pronastic.

Aixf doncs, hem demostrat que LIF actua corn un supressor immunologic en processos tumorals, recapitulant la seva funcio normal en altres processos biologics. LIF es un pont entre la resposta immunolagica innata i I'adaptativa a traves de la induccio de la secrecio de CCL22 de les TAMCs, i la posterior regulacio de les Tregs, Teff i NKs. Els nostres resultats identifiquen LIF corn una diana terapeutica immuno-oncolagica prometedora i estableixen el potencial translacional d'agents inhibidors de LIF.