Interactions between the immune system and breast cancer

Energy imbalance and cancer: Cause or consequence?

Obesity has been an epidemic worldwide over the past decades and significantly increases the risk of developing a variety of deadly diseases including type 2 diabetes, cardiovascular diseases and many cancers. The relationship between obesity and type 2 diabetes and cardiovascular disease has been well documented. The drastically increased frequency of a number of cancers in obesity has attracted growing interest. On one hand, how increased adiposity promotes cancer development remains poorly understood, despite the fact that considerable epidemiological evidence has suggested links between them. On the other hand, however, numerous studies have shown that tumorigenesis leads to substantial weight loss in a large portion of cancer patients. Here, we summarize the recent advances on our understanding of the link between obesity and cancer development with a focus on the molecular mechanisms accounting for the rising cancer incidence in the context of obesity. In addition, we also discuss how cancer-associated anorexia and cachexia causes weight loss. © 2017 IUBMB Life, 69(10):776-784, 2017.

Current perspectives of molecular pathways involved in chronic inflammation-mediated breast cancer

Inflammation has multifaceted role in cancer progression including initiation, promotion and invasion by affecting the immune surveillance and associated signaling pathways. Inflammation facilitates the over-expression of cytokines, chemokines and growth factors involved in progression of different cancers including breast cancer progression. Deregulation of biological processes such as oxidative stress, angiogenesis, and autophagy elicit favorable immune response towards chronic inflammation. Apart from the role in carcinogenesis, chronic inflammation also favors the emergence of drug resistance clones by inducing the growth of breast cancer stem-like cells. Immunomodulation mediated by cytokines, chemokines and several other growth factors present in the tumor microenvironment regulate chronic inflammatory response and alter crosstalk among various signaling pathways such as NF-κB, Nrf-2, JAK-STAT, Akt and MAPKs involved in the progression of breast cancer. In this review, we focused on cellular and molecular processes involved in chronic inflammation, crosstalk among different signaling pathways and their association in breast cancer pathogenesis.

Inflammation, a key event in cancer development

Several recent studies have identified nuclear factor-kappaB as a key modulator in driving inflammation to cancers. Besides this transcription factor, essential in regulating inflammation and cancer development, an inflammatory microenvironment inhabiting various inflammatory cells and a network of signaling molecules are also indispensable for the malignant progression of transformed cells, which is attributed to the mutagenic predisposition of persistent infection-fighting agents at sites of chronic inflammation. As a subverted host response to inflammation-induced tumors, the inflammatory cells and regulators may facilitate angiogenesis and promote the growth, invasion, and metastasis of tumor cells. Thus far, research regarding inflammation-associated cancer development has focused on cytokines and chemokines as well as their downstream targets in linking inflammation and cancer. Moreover, other proteins with extensive roles in inflammation and cancer, such as signal transducers and activators of transcription, Nrf2, and nuclear factor of activated T cells, are also proposed to be promising targets for future studies. The elucidation of their specific effects and interactions will accelerate the development of novel therapeutic interventions against cancer development triggered by inflammation.

Phenotyping of lymphocytes expressing regulatory and effector markers in infiltrating ductal carcinoma of the breast

Dysfunction of the host immune system in cancer patients can be due to a number of reasons including suppression of tumour associated antigen reactive lymphocytes by regulatory T (Treg) cells. In this study, we used flow cytometry to determine the phenotype and relative abundance of the tumour infiltrating lymphocytes (TILs) from 47 enzymatically dissociated tumour specimens from patients with infiltrating ductal carcinoma (IDC) of the breast. The expression of both effector and regulatory markers on the TILs were determined by using a panel of monoclonal antibodies. Analysis revealed CD8(+) T cells (23.4+/-2.1%) were predominant in TILs, followed by CD4(+) T cells (12.6+/-1.7%) and CD56(+) natural killer cells (6.4+/-0.7%). The CD4(+)/CD8(+) ratio was 0.8+/-0.9%. Of the CD8(+) cells, there was a higher number (68.4+/-3.5%) that expressed the effector phenotype, namely, CD8(+)CD28(+) and about 46% of this subset expressed the activation marker, CD25. Thus, a lower number of infiltrating CD8(+) T cells (31.6+/-2.8%) expressed the marker for the suppressor phenotype, CD8(+)CD28(-). Of the CD4(+) T cells, 59.6+/-3.9% expressed the marker for the regulatory phenotype, CD4(+)CD25(+). About 43.6+/-3.8% CD4(+)CD25(+) subset co-expressed both the CD152 and FOXP3, the Treg-associated molecules. A positive correlation was found between the presence of CD4(+)CD25(+) subset and age (> or =50 years old) (r=0.51; p=0.045). However, no significant correlation between tumour stage and CD4(+)CD25(+) T cells was found. In addition, we also found that the CD4(+)CD25(-) subset correlated with the expression of the nuclear oestrogen receptor (ER)-alpha in the tumour cells (r=0.45; p=0.040). In conclusion, we detected the presence of cells expressing the markers for Tregs (CD4(+)CD25(+)) and suppressor (CD8(+)CD28(-)) in the tumour microenvironment. This is the first report of the relative abundance of Treg co-expressing CD152 and FOXP3 in breast carcinoma.

Immunocytochemical demonstration of down regulation of HLA class-I molecule expression in human metastatic breast carcinoma

Deficient expression of HLA class-I molecules observed in many cancers is suggested to influence both disease progression and potential efficacy of T cell-mediated immune therapy. Previous studies have attempted to correlate either primary breast cancer tumor grade with HLA class-I levels or the presence of HLA class-I-deficient cells in metastatic lesions with survival. In this study we evaluated the HLA class-I status of matched primary and secondary breast cancer lesions in order to ask the question: is metastasis of breast cancer associated with down-regulation of HLA class-I expression? Immunocytochemistry analysis shows a definitive correlation between diminished HLA class-I expression and dissemination of breast cancer to tumor-draining lymph nodes: both the total number of HLA class-I+ cells per sample and the levels of expression are dramatically decreased in secondary versus primary tumor lesions. These findings are consistent with the contention that the ability of breast cancer cells to escape the confines of the original tumor lesion requires down-regulation of HLA class-I expression and implies that enhancing HLA class-I expression in secondary breast cancer may have a beneficial effect on T-cell-mediated immunotherapy.

Tumor-associated antigen profiling in breast and ovarian cancer: mRNA, protein or T cell recognition?

PURPOSE

The absence of tumor-associated antigens (TAA) which might elicit an immune response is one reason for the disappointing results of therapeutical vaccines in cancer patients. Moreover, impaired expression of MHC class-I and components involved in antigen processing, such as TAP-1, -2, LMP-2, -7, and MECL-1, may lead to tumor escape from immune recognition. Expression profiling of TAA is one approach towards the design of well-defined and individualized anti-tumor vaccines.

METHODS

Quantitative polymerase chain reaction (qRT-PCR) is the method of choice to characterize immunologically relevant properties of individual tumors. However, the application of qRT-PCR as a surrogate parameter for the expression of TAAs depends upon the assumption that the level of an mRNA species correlates with the cellular level of the protein it encodes. Therefore, we additionally analyzed TAA expression by immunofluorescence and T cell recognition.

RESULTS

In the present study we were unable to confirm that impaired TAP-1 or -2 (transporter associated with antigen processing) expression characterized at the mRNA level is an appropriate surrogate parameter for down-regulated MHC class-I expression in breast cancer. In addition, we analyzed the expression pattern of TAAs in breast and ovarian cancer cell lines. Besides the well-known over-expression of HER-2/neu, CEA, and MUC-1, multiple antigens of the MAGE-family were frequently co-expressed. We investigated whether detection of TAAs by qRT-PCR correlates with monoclonal antibody staining, and which method could predict T cell recognition. We demonstrated a correlation between tumor cell lysis by HLA-A*0201-restricted, MUC-1-specific CTL and threshold levels of MUC-1-specific mRNA.

CONCLUSION

MUC-1 is an example that TAA profiling by RT-PCR and flow cytometry can fail to correlate with each other and are of limited value in the prediction of T cell recognition.

Endothelial cell-based systemic gene therapy of metastatic melanoma

Cancer metastasis accounts for a significant proportion of morbidity and mortality in patients. Effective means of treating disseminated disease remains elusive. The purpose of this study was to determine whether genetically modified endothelial cells (GMEC) can selectively target and deliver recombinant therapeutic molecules to sites of tumor metastases. Following the establishment of lung metastases of 4T1 mammary tumor in mice, intravenously (i.v.) administered, lacZ transgene-expressing endothelial cells (lacZ-GMEC) accumulated at the tumor sites. An average of 32% and 90% of the pulmonary metastases were X-gal stained following one and three tail vein injections of 10(5) lacZ-GMEC, respectively. The linear pattern of X-gal staining seen within the tumor sites and the histological appearance of the tumor vasculature were consistent with the incorporation of lacZ-GMEC into blood vessels. In C57Bl/6 mice harboring lung metastases of melanoma, the administration of three sequential i.v. injections of 10(5) endothelial cells expressing a human interleukin 2 transgene abrogated the tumor metastases and prolonged survival of the animals. These results demonstrate that i.v.-administered GMEC can selectively accumulate, survive, and stably express exogenous genes at multiple tumor sites. These findings support a role for i.v.-administered GMEC as a potential therapeutic strategy for the systemic treatment of cancer metastases.

Altered expression of HLA class I antigens in breast cancer: association with prognosis

Loss of surface expression of class I major histocompatibility antigens is commonly observed in malignant tumors and has been considered one of the mechanisms for escape from cytotoxic T cells. However, natural killer cells kill cells lacking HLA class I antigens. In the present study, we characterized by immunohistochemistry the HLA class I expression of breast carcinomas from 187 patients with TNM stages I and II, diagnosed 1981-1984, using beta(2)-microglobulin as a marker and evaluated the effect on survival with a follow-up of up to 14 years. The largest group (48%) consisted of HLA class I-negative tumors (< or =10% of cells stained), mixed expression (>10% and <80% of cells stained) was seen in 36% and only 15% were classified as HLA class I-positive (> or=80% cells stained). No associations could be established with various clinicopathological parameters, such as tumor size, presence of lymph node metastases, histological grade, expression of hormone receptors, S phase and p53 mutations. There was no effect on recurrence-free survival in the whole group; but among node-negative patients (n = 86), those who had tumors with mixed HLA class I expression had a significantly higher probability of disease recurrence (OR = 3.42, p = 0.014) than patients with either HLA class I-positive or -negative tumors, particularly after more than 5 years. In node-positive patients who received adjuvant therapy, this phenotype was not associated with disease recurrence.

Docetaxel-induced mobilization of hematopoietic stem cells in a murine model: kinetics, dose titration, and toxicity

OBJECTIVE

Docetaxel (DXT) is an anticancer agent that has demonstrated therapeutic efficacy against solid tumors, particularly breast cancer. Based on the use of hematopoietic stem cell (HSC) transplantation to restore hematopoietic reconstitution after myeloablative therapy, this study was performed to determine if DXT could mobilize HSCs in vivo.

MATERIALS AND METHODS

C57Bl/6 mice were injected intraperitoneally with varying doses of DXT (equivalent to human doses of 40 to 120 mg/m(2)). Spleens were harvested on days 2, 4, 6, 8, 10, and 12 after DXT administration for recovery of mononuclear cells (MNCs). The number of HSCs present within the MNCs was determined by clonogenic assay for colony-forming units in culture (CFU-C) and by FACS analysis for CD34(+) cells. Peripheral blood samples were obtained at the time of spleen harvest to determine the hematologic profile. Liver and renal function tests were performed to monitor toxicity.

RESULTS

DXT mobilize d HSCs in a dose- and time-dependent manner. When measured by the CFU-C assay, maximal mobilization of HSC (>10-fold increase in control; p<0.01) was observed at a dose of 30 mg/kg (equivalent to human dose of 75 mg/m(2)) on day 7. The number of mobilized HSCs peaked on days 6 to 8 at all doses of DXT tested. There was no evidence of weight loss, liver, or renal toxicity at any of the DXT doses tested.

CONCLUSION

These results indicate that DXT efficiently mobilizes HSCs in a murine model and provide the rationale for similar studies in a clinical trial.

The immunology and immunotherapy of breast cancer: an update

Adenocarcinomas of the breast behave clinically and epidemiologically in ways that show host resistance factors are important for outcome in addition to grade and stage of malignancy. Immune reactivity to autologous tumors is indicated by the general presence of lymphoid infiltration (LI) and regional lymph node changes; however, these changes predict favorable outcome only in non-metastatic disease. LI is characterized by CD4+ and CD8+ tumor infiltrating lymphocytes reflecting latent cell-mediated immunity (CMI). CMI and humoral immune reactivity have been demonstrated to autologous tumor and a variety of tumor-associated antigens (TAA) have been implicated including CEA, HER-2/neu, MAGE-1, p53, T/Tn and MUC-1. Immune incompetence involving CMI is progressive with the stage of breast cancer and is prognostically significant. Immunotherapy of several types has been designed to address this immunodeficiency and the TAAs involved. Animal models have employed drug therapy, cytokine transfection, vaccines with autologous tumor, cytokines like interferon alpha (IFN-alpha) and interleukin-2 (IL-2), TAA tumor vaccines, and immunotoxins with evidence of tumor regression by immunologic means. Immunotherapy of human breast cancer is a rapidly growing experimental area. Positive results have been obtained with natural IFN and interleukins, particularly in combination strategies (but not with high dose recombinant IFN or IL-2), with autologous tumor vaccine (but not yet with transfected autologous tumor); with a mucin carbohydrate vaccine (Theratope) in a combination strategy (but not with mucin core antigen) and with several immunotoxins. Combination strategies involving immunorestoration, contrasuppression, adjuvant, and immunotoxins are suggested for the future.

Functional analysis of tumor-infiltrating leukocytes in breast cancer patients

BACKGROUND

The immune system is capable of responding to cancer as evidenced by systemic, regional, and intratumoral leukocyte activation. For individual patients there is no predictable relationship between leukocyte composition, or function, and the prognosis of the disease.

MATERIALS AND METHODS

Leukocytes from tumor tissues (TIL, n = 17), axillary lymph nodes (LNL, n = 26), and peripheral blood (PBL, n = 25) of human breast cancer patients were evaluated for the ability to synthesize type 1 cytokines (TNF alpha, IFN gamma, and IL-2) and type 2 cytokines (IL-4, IL-6, and IL-10) by flow cytometry. The capacity of these cells to mediate in vitro cytotoxicity against the ZR 75-1 breast cancer cell line was simultaneously evaluated.

RESULTS

To cells (CD3+) were the major leukocyte population detected in each tissue with CD4+ cells being predominant in TIL, LNL, and PBL. Type 1 cytokines were the predominant type produced by stimulated T cells for each population with a statistically greater proportion of IFN gamma + T cells in TIL as compared with LNL and PBL (P = 0.013 and 0.04, respectively). However, LNL and PBL had a significantly greater proportion of IL2+ T cells as compared with TIL from the same patient (P = 0.02 and 0.01, respectively). The tumoricidal function could be stimulated with recombinant human IL-2 in each leukocyte population with substantially higher levels of activity being produced in TIL from node-positive as compared with node-negative patients.

CONCLUSIONS

This study demonstrates that there are differences in the capacity of leukocytes from different anatomical sites of breast cancer patients to synthesize immunostimulatory cytokines and mediate tumor cell cytotoxicity. Such differences may reflect prognostically distinct subgroups of patients and might also provide a rationale for the development of biological approaches to therapy in selected patients.