Human breast cancer cells enhance self tolerance by promoting evasion from NK cell antitumor immunity

Abstract

NK cells are a major component of the antitumor immune response and are involved in controlling tumor progression and metastases in animal models. Here, we show that dysfunction of these cells accompanies human breast tumor progression. We characterized human peripheral blood NK (p-NK) cells and malignant mammary tumor-infiltrating NK (Ti-NK) cells from patients with noninvasive and invasive breast cancers. NK cells isolated from the peripheral blood of healthy donors and normal breast tissue were used as controls. With disease progression, we found that expression of activating NK cell receptors (such as NKp30, NKG2D, DNAM-1, and CD16) decreased while expression of inhibitory receptors (such as NKG2A) increased and that this correlated with decreased NK cell function, most notably cytotoxicity. Importantly, Ti-NK cells had more pronounced impairment of their cytotoxic potential than p-NK cells. We also identified several stroma-derived factors, including TGF-β1, involved in tumor-induced reduction of normal NK cell function. Our data therefore show that breast tumor progression involves NK cell dysfunction and that breast tumors model their environment to evade NK cell antitumor immunity. This highlights the importance of developing future therapies able to restore NK cell cytotoxicity to limit/prevent tumor escape from antitumor immunity. IntroductionBreast cancer (BC) is the primary cause of cancer deaths in women. The main cause of this mortality is the metastatic spread to other organs (1). Metastasis occurs when tumor cells acquire invasive features (2) and the ability to escape from antitumor immunity (3, 4). Defects in antitumor immunity may also facilitate BC occurrence. Indeed, mice deficient in IFN-γ production spontaneously develop mammary tumors (5). Breast tumor cells transplanted into NOD/SCID mice (which lack adaptive immunity) form noninvasive tumors, whereas the same cells transplanted into NOD/SCID/γ-c null mice (no adaptive immunity and no NK cells) form invasive tumors that metastasize rapidly (6). This effect is strictly dependent on NK cells (7). Similarly, in a highly metastatic model, BC metastasized to the lung only after elimination of NK cells by Tregs (8).Advanced BC patients show defects in antitumor immunity, such as alterations of DC maturation (9) and an increase in Treg infiltrates (10). Major impairment of peripheral blood NK cell maturation and cytotoxic functions has also been reported in metastatic BC (11). Several gene expression profiling studies have shown that a better outcome is associated with a strong cytotoxic infiltrate containing NK cells (12)(13)(14)(15). These data suggest that BC progression is linked to antitumor immunity efficiency and particularly to NK cells. However, the precise relationships between NK cells and BC progression in humans have not been studied so far.

Natural killer cells phenotypic characterization as an outcome predictor of HCV-linked HCC after curative treatments

“…10,21 HLA-E expression has been observed in hepatocytes and appears to be increased in human HCC by Granulin-epithelin precursor, a hepatic oncofetal protein overexpressed in HCC. 22 By contrast, the enrichment of NKp46-and NKp30-positive NK-cells in HCCs with worse prognosis is in apparent contradiction with the activating function of these receptors, even though the above mentioned low expression of CD3z may reflect poor or absent receptor signaling.…”

“…The importance of NKcell receptors in mediating antitumor immune response is further supported by the identification of several mechanisms of immune escape, mainly consisting in the downregulation of activating receptors and their ligands, or alternatively in the upregulation of inhibitory receptor-ligand pairs. [9][10][11][12] Additional mechanisms of immune evasion have also been described, such as escape from NKG2D-mediated immunosurveillance through shedding of NKG2D ligand MICA. 13 Few data are available about the role played by NK receptor expression and signaling in the determination of HCC outcome.…”

The Immune Microenvironment of Human Tumors: General Significance and Clinical Impact

“…The case of B lymphocytes is also unclear: they correlate with tumor growth and invasion in murine models [44][45][46][47] but scarce observations associate a B cells signature to good prognosis in several human cancers [48][49][50]. Intratumoral NK cells have been reported to down regulate their activating receptors and to be associated to larger breast [51] and lung [28] tumors, but without clear impact on patients survival. In other cancers, however, NK cell density rather correlates with good prognosis [14].…”

Epigenetic priming of both tumor and NK cells augments antibody-dependent cellular cytotoxicity elicited by the anti-PD-L1 antibody avelumab against multiple carcinoma cell types

“…It has been shown that NK cells from cancer patients’ PBMCs have decreased expression of activation receptors and functional defects; 49,50 we thus investigated if entinostat treatment could increase the activation phenotype of these NK cells. PBMCs from seven heavily pretreated metastatic breast cancer patients were treated for 48 hours with a clinically relevant exposure of entinostat or DMSO.…”

“…Moreover, the fact that NK cells from heavily pretreated breast cancer patients had phenotypic changes after exposure to entinostat similar to healthy donor NK cells was a key novel finding of our study since it has been shown that cancer patients often have dysfunctional NK cells that are lacking an active phenotype. 49,50 …”