Role of prolactin receptor and CD25 in protection of circulating T lymphocytes from apoptosis in patients with breast cancer

The Peripheral Immune Landscape of Breast Cancer: Clinical Findings and In Vitro Models for Biomarker Discovery

Breast cancer is the deadliest female malignancy worldwide and, while much is known about phenotype and function of infiltrating immune cells, the same attention has not been paid to the peripheral immune compartment of breast cancer patients. To obtain faster, cheaper, and more precise monitoring of patients' status, it is crucial to define and analyze circulating immune profiles. This review compiles and summarizes the disperse knowledge on the peripheral immune profile of breast cancer patients, how it departs from healthy individuals and how it changes with disease progression. We propose this data to be used as a starting point for validation of clinically relevant biomarkers of disease progression and therapy response, which warrants more thorough investigation in patient cohorts of specific breast cancer subtypes. Relevant clinical findings may also be explored experimentally using advanced 3D cellular models of human cancer-immune system interactions, which are under intensive development. We review the latest findings and discuss the strengths and limitations of such models, as well as the future perspectives. Together, the scientific advancement of peripheral biomarker discovery and cancer-immune crosstalk in breast cancer will be instrumental to uncover molecular mechanisms and putative biomarkers and drug targets in an all-human setting.

Prolactin Rescues Immature B Cells from Apoptosis-Induced BCR-Aggregation through STAT3, Bcl2a1a, Bcl2l2, and Birc5 in Lupus-Prone MRL/lpr Mice

Self-reactive immature B cells are eliminated through apoptosis by tolerance mechanisms, failing to eliminate these cells results in autoimmune diseases. Prolactin is known to rescue immature B cells from B cell receptor engagement-induced apoptosis in lupus-prone mice. The objective of this study was to characterize in vitro prolactin signaling in immature B cells, using sorting, PCR array, RT-PCR, flow cytometry, and chromatin immunoprecipitation. We found that all B cell maturation stages in bone marrow express the prolactin receptor long isoform, in both wild-type and MRL/lpr mice, but its expression increased only in the immature B cells of the latter, particularly at the onset of lupus. In these cells, activation of the prolactin receptor promoted STAT3 phosphorylation and upregulation of the antiapoptotic Bcl2a1a, Bcl2l2, and Birc5 genes. STAT3 binding to the promoter region of these genes was confirmed through chromatin immunoprecipitation. Furthermore, inhibitors of prolactin signaling and STAT3 activation abolished the prolactin rescue of self-engaged MRL/lpr immature B cells. These results support a mechanism in which prolactin participates in the emergence of lupus through the rescue of self-reactive immature B cell clones from central tolerance clonal deletion through the activation of STAT3 and transcriptional regulation of a complex network of genes related to apoptosis resistance.

The role of prolactin in central nervous system inflammation

Prolactin has been shown to favor both the activation and suppression of the microglia and astrocytes, as well as the release of inflammatory and anti-inflammatory cytokines. Prolactin has also been associated with neuronal damage in diseases such as multiple sclerosis, epilepsy, and in experimental models of these diseases. However, studies show that prolactin has neuroprotective effects in conditions of neuronal damage and inflammation and may be used as neuroprotector factor. In this review, we first discuss general information about prolactin, then we summarize recent findings of prolactin function in inflammatory and anti-inflammatory processes and factors involved in the possible dual role of prolactin are described. Finally, we review the function of prolactin specifically in the central nervous system and how it promotes a neuroprotective effect, or that of neuronal damage, particularly in experimental autoimmune encephalomyelitis and during excitotoxicity. The overall studies indicated that prolactin may be a promising molecule for the treatment of some neurological diseases.

A Pilot Randomized Trial Assessing the Effect of a Psychoeducational Intervention on Psychoneuroimmunological Parameters Among Patients With Nonmetastatic Breast Cancer

OBJECTIVE

The aim of this study was to determine a potential benefit of the specific psychoeducational intervention "Learning to Live with Cancer" (LTLWC) for patients with operated nonmetastatic breast cancer, with respect to psychological variables and endocrine and immune parameters.

METHODS

Fifty-two postmenopausal women with operated stage I to III breast cancer were randomized to either a breast cancer intervention group (BCIG, n = 30) who immediately began participating in the LTLWC intervention program or to a breast cancer control group (BCCG, n = 22). Matched healthy women were asked to participate as a noncancer comparison group (n = 26). All participants were evaluated at three different time points (t1-t3) using a set of standardized questionnaires and blood samples were taken to analyze immune cell subsets and stress hormone levels.

RESULTS

A significant reduction in trait anxiety/State Trait Anxiety Inventory score was observed in the BCIG (t1: median = 35.0 [interquartile range = 28.0-38.0] versus t3: median = 26.0 [interquartile range = 18.5-37.0], p = .0001) compared with the BCCG (t1: median = 41.0 [interquartile range =32.75-49.0]; t3: median = 38.5 [interquartile range = 30.75-46.5], p = .01524; p interaction = .001). In parallel, a significant rise of serotonin levels (t1: median = 66.5 ng/ml [interquartile range = 11.50-106.00] versus t3: median = 80.5 ng/ml [interquartile range =59.00-118.00], p = .00008) as well as a significant reduction of the elevated number of Treg cells at baseline (t1: median = 4.45% [interquartile range = 4.00-5.33] versus t3: median = 2.80% [interquartile range = 2.68-3.13], p < .00001) were observed in the BCIG versus no change in the BCCG. A significant statistical association between reduced trait anxiety and decreased Treg cell number could be demonstrated in the BCIG (r = .62, p < .01).

CONCLUSIONS

The observed results of this study provide preliminary support for the efficacy of the LTLWC program in significantly improving psychoneuroimmunological parameters in patients with nonmetastatic breast cancer.

Interleukin-2 chronotherapy for metastatic renal cell carcinoma: Results of a phase I-II study

BACKGROUND

Interleukin-2 (IL-2) was the cornerstone treatment for metastatic renal cell carcinoma (RCC) until the advent of tyrosine kinase inhibitors, but it still has therapeutic value. As a single bolus of IL-2 causes toxicity, there is interest in administration regimens with better tolerability and efficacy. Chronotherapy is the administration of therapy according to the circadian rhythm's influence on the immune and hormonal systems. This phase I-II trial evaluated the safety of IL-2 chronotherapy in metastatic RCC patients and determined the maximum tolerated dose. The secondary objective was to identify prognostic factors for survival.

METHODS

Three chronomodulation schedules (5:00-13:00, 13:00-21:00, and 21:00-5:00) were tested. Each schedule was an 8-h IL-2 infusion, with a Gaussian distribution of drug concentration peaking at 4 h. To identify the maximum tolerated dose, the dose for different patients was escalated from 2 MIU/m² (level I) to 18.6 MIU/m² (level VI).

RESULTS

Thirty patients were enrolled and completed treatment. Two patients were treated at 5:00-13:00, 15 at 13:00-21:00, and 13 at 21:00-5:00. Nine cases of grade 3 toxicity occurred in 7 patients at the highest dose (18.6 MIU/m²); no grade 4 toxicity occurred. The maximum tolerated dose was 14.0 MUI/m². Patients were followed for a median of 16 months (range, 2-107). One patient was lost to follow-up, 3 patients were alive at last contact, and 26 patients died. Six patients achieved long-term survival (≥48 months). There was one complete response, four partial responses, 11 cases of stable disease and 14 of progressive disease. The response rate was 16% (5/30) and disease-control rate was 53% (16/30). Median progression-free survival was 4.5 months, and median overall survival was 14.5 months. Kaplan-Meier analyses revealed significant associations between overall survival and ECOG performance score (0 vs. 1-2), MSKCC score (0-2 vs. ≥ 3), IMDC risk score (0-2 vs. ≥ 3), IL-2 dose level (IV-VI vs. I-III), and prolactin (increase vs. no increase), and but not for chronotherapy schedule.

CONCLUSION

IL-2 chronotherapy appears to be safe, moderately toxic and active in metastatic RCC. It may represent a new modality of IL-2 administration for these patients.

Extrapituitary prolactin promotes generation of Eomes-positive helper T cells mediating neuroinflammation

We have previously demonstrated that induction of pathogenic eomesodermin-positive CD4⁺ T cells (Eomes⁺ T helper [Th] cells) is associated with transition from an acute stage to a later stage of experimental autoimmune encephalomyelitis (EAE). In the late phase of EAE, B cells and non-B cell antigen-presenting cells (APCs) recruited to the central nervous system strikingly up-regulate prolactin (PRL). The PRL-producing APCs have the potential to promote generation of Eomes⁺ Th cells from naïve T cells in an MHC class II-restricted manner, and therapies inhibitory for PRL production suppress the induction of Eomes⁺ Th cells and ameliorate clinical signs of EAE. Our study highlights the unexpected role of extrapituitary PRL in the development of persistent neuroinflammation.

Induction of eomesodermin-positive CD4⁺ T cells (Eomes⁺ T helper [Th] cells) has recently been correlated with the transition from an acute stage to a later stage of experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. Moreover, these cells’ pathogenic role has been experimentally proven in EAE. While exploring how the pathogenic Eomes⁺ Th cells are generated during the course of EAE, we unexpectedly found that B cells and MHC class II⁺ myeloid cells isolated from the late EAE lesions strikingly up-regulated the expression of prolactin (PRL). We demonstrate that such PRL-producing cells have a unique potential to induce Eomes⁺ Th cells from naïve T cells ex vivo, and that anti-MHC class II antibody could block this process. Furthermore, PRL levels in the cerebrospinal fluid were significantly increased in the late phase of EAE, and blocking the production of PRL by bromocriptine or Zbtb20-specific siRNA significantly reduced the numbers of Eomes⁺ Th cells in the central nervous system (CNS) and ameliorated clinical signs in the later phase of EAE. The PRL dependency of Eomes⁺ Th cells was confirmed in a series of in vitro and ex vivo experiments. Collectively, these results indicate that extrapituitary PRL plays a crucial role in the CNS inflammation mediated by pathogenic Eomes⁺ Th cells. Cellular interactions involving PRL-producing immune cells could be considered as a therapeutic target for the prevention of chronic neuroinflammation.

Prolactin: Friend or Foe in Central Nervous System Autoimmune Inflammation?

The higher prevalence of multiple sclerosis (MS) in females, along with the modulation of disease activity observed during pregnancy and the post-partum period, has suggested a hormonal influence in MS. Even if prolactin (PRL) does not belong to the sex hormones family, its crucial role in female reproduction and lactation has prompted great efforts to understand if PRL could represent a gender factor in the pathogenesis of MS and experimental autoimmune encephalomyelitis (EAE), the animal model for this disease. Extensive literature has documented a remarkable immune-stimulating potential for this hormone, indicating PRL as a disease-promoting factor in MS and EAE. However, recent work has pointed out that PRL is endowed with important neuroprotective and remyelinating properties and has encouraged a reinterpretation of the involvement of this hormone in MS. In this review we summarize both the protective functions that PRL exerts in central nervous system tissue as well as the inflammatory activity of this hormone in the context of autoimmune responses against myelin. Last, we draw future lines of research that might help to better clarify the impact of PRL on MS pathology.

Carboxypeptidase-D is elevated in prostate cancer and its anti-apoptotic activity is abolished by combined androgen and prolactin receptor targeting

BACKGROUND

Carboxypeptidase-D (CPD) cleaves C-terminal arginine for nitric oxide (NO) production. CPD and NO levels are upregulated by testosterone (T) and prolactin (PRL) to promote survival of prostate cancer (pCa) cells. This study evaluated CPD immunostaining and T/PRL regulation of CPD and NO levels in benign and malignant prostate tissues/cells to determine the role of CPD in pCa.

METHODS

Immunohistochemistry (IHC) and tissue microarrays (TMA) were used to determine CPD immunostaining in prostate specimens. QPCR and immunoblotting were used to quantify CPD mRNA/protein expression in prostate cells. NO production was measured using 4,5-diaminofluorescein diacetate assay.

RESULTS

CPD staining increased from 8.9 ± 3.8% (Mean ± SEM, n = 15) of benign epithelial cell area to 30.9 ± 2.9% (n = 30) of tumor cell area in one set of TMAs (P = 0.0008) and from 5.9 ± 0.9% (n = 45) of benign epithelial cell area to 18.8 ± 1.9% (n = 55) of tumor area in another (P < 0.0001). IHC of prostate tissues (≥50 mm(2)) confirmed increased CPD staining, from 13.1 ± 2.9% in benign (n = 16) to 29.5 ± 4.4% in pCa (n = 31, P = 0.0095). T and/or PRL increased CPD expression in several pCa but not benign cell lines. T and PRL acted synergistically to increase NO production, which was abolished only when receptor antagonists flutamide and Δ1-9-G129R-hPRL were used together.

CONCLUSIONS

CPD immunostaining and T/PRL-stimulated CPD expression were higher in pCa than benign tissues/cells. Elevated CPD increased NO production, which was abolished when both AR and PRLR were inhibited. Our study implicates a critical role for the T/PRL-stimulated CPD-Arg-NO pathway in pCa progression, and suggests that AR+PRLR inhibition is a more effective treatment for pCa.

The role of activation-induced cell death in the higher onset of spontaneous apoptosis of NK cell subsets in patients with metastatic epithelial cancer

To address the question whether the higher onset of apoptosis of circulating NK cell subsets might be activation induced in cancer patients, surface expression of NKG2D and serum (s) levels of MHC class I chain-related (MIC) proteins in relation to apoptosis marker and CD95 expression on NK cells were evaluated. Patients showed a significantly higher onset of spontaneous apoptosis of CD56dim NK cells. No difference in the CD95 expression could be detected between patients and normal controls (NCs). Patients' CD56bright NK cells demonstrated a higher expression of NKG2D compared to CD56dim NK cells. The sMICB levels showed a higher level in patients versus NCs. No correlation between sMIC protein levels with both NKG2D expression and onset of spontaneous apoptosis of NK cell subsets was found. Our data suggest that the higher onset of apoptosis of circulating NK cell subsets of patients is not triggered by activation-induced cell death.

Resistance to apoptosis and expansion of regulatory T cells in relation to the detection of circulating tumor cells in patients with metastatic epithelial cancer

Regulatory T cells may be crucial in the development of T cell tolerance to malignancies and contribute to immune dysfunctions. We investigated the percentage, activity, and onset of apoptosis of T cell subpopulations by multicolor flow cytometry in metastatic epithelial cancer patients compared to normal controls. Furthermore, a possible relationship between the presence of circulating tumor cells detected by immunocytochemistry and immune cell abnormalities was evaluated. Our study demonstrated a significantly elevated proportion of regulatory T cells in cancer patients (p < 0.001). In contrast to all other T cell subpopulations, regulatory T cells showed comparable Annexin V-binding characteristics in patients and normal controls. No relationship between the detection of circulating tumor cells and immune dysfunction was observed. These results indicate that cancer patients have a higher number of regulatory T cells with resistance to apoptotic stimuli partly responsible for immune dysfunctions as often observed in cancer patients.

Tumor-driven evolution of immunosuppressive networks during malignant progression

Tumors evolve mechanisms to escape immune control by a process called immune editing, which provides a selective pressure in the tumor microenvironment that could lead to malignant progression. A variety of tumor-derived factors contribute to the emergence of complex local and regional immunosuppressive networks, including vascular endothelial growth factor, interleukin-10, transforming growth factor-beta, prostaglandin E(2), and soluble phosphatidylserine, soluble Fas, soluble Fas ligand, and soluble MHC class I-related chain A proteins. Although deposited at the primary tumor site, these secreted factors could extend immunosuppressive effects into the local lymph nodes and the spleen, promoting invasion and metastasis. Vascular endothelial growth factors play a key role in recruiting immature myeloid cells from the bone marrow to enrich the microenvironment as tumor-associated immature dendritic cells and tumor-associated macrophages. The understanding of the immunosuppressive networks that evolve is incomplete, but several features are emerging. Accumulation of tumor-associated immature dendritic cells may cause roving dendritic cells and T cells to become suppressed by the activation of indoleamine 2,3-dioxygenase and arginase I by tumor-derived growth factors. Soluble phosphatidylserines support tumor-associated macrophages by stimulating the release of anti-inflammatory mediators that block antitumor immune responses. Soluble Fas, soluble FasL, and soluble MHC class I-related chain A proteins may help tumor cells escape cytolysis by cytotoxic T cells and natural killer cells, possibly by counterattacking immune cells and causing their death. In summary, tumor-derived factors drive the evolution of an immunosuppressive network which ultimately extends immune evasion from the primary tumor site to peripheral sites in patients with cancer.