Growth of MCF-7 human breast carcinoma in severe combined immunodeficient mice: growth suppression by recombinant interleukin-2 treatment and role of lymphokine-activated killer cells

Costimulation with anti-cluster of differentiation 3 and anti-cluster of differentiation 28 reduces the activity of mucin 1-stimulated human mononuclear cells

Cytotoxic T-lymphocyte activation and extension of the cell life span is necessary in order to enable immunotherapy to perform effectively against cancer. In the present study, mucin 1 (MUC1)-stimulated human mononuclear cells (M1SHMCs) were costimulated with bead-attached monoclonal antibodies specific for cluster of differentiation (CD)3 and CD28 receptors. The study was undertaken to determine whether costimulation was capable of enhancing the killing of cancer cells in vitro and of protecting non-obese diabetic severe combined immunodeficient mice from tumor development. Lysis of MCF-7 tumor cells by M1SHMCs was reduced following costimulation with anti-CD3 and anti-CD28. Furthermore, costimulation with anti-CD3 and anti-CD28 eliminated the protective effects of M1SHMCs on MCF-7 breast cancer cell growth in the non-obese diabetic severe combined immunodeficient mice. The present study suggested that costimulation with anti-CD3 and anti-CD28 is not advisable following antigen activation of lymphocytes under the conditions used here. Using a lower anti-CD3/CD28 bead to T-cell ratio may prevent immune suppression, however, further studies are required to support this hypothesis.

The effect of a DNA repair gene on cellular invasiveness: XRCC3 over-expression in breast cancer cells

Over-expression of DNA repair genes has been associated with resistance to radiation and DNA-damage induced by chemotherapeutic agents such as cisplatin. More recently, based on the analysis of genome expression profiling, it was proposed that over-expression of DNA repair genes enhances the invasive behaviour of tumour cells. In this study we present experimental evidence utilizing functional assays to test this hypothesis. We assessed the effect of the DNA repair proteins known as X-ray complementing protein 3 (XRCC3) and RAD51, to the invasive behavior of the MCF-7 luminal epithelial-like and BT20 basal-like triple negative human breast cancer cell lines. We report that stable or transient over-expression of XRCC3 but not RAD51 increased invasiveness in both cell lines in vitro. Moreover, XRCC3 over-expressing MCF-7 cells also showed a higher tumorigenesis in vivo and this phenotype was associated with increased activity of the metalloproteinase MMP-9 and the expression of known modulators of cell-cell adhesion and metastasis such as CD44, ID-1, DDR1 and TFF1. Our results suggest that in addition to its' role in facilitating repair of DNA damage, XRCC3 affects invasiveness of breast cancer cell lines and the expression of genes associated with cell adhesion and invasion.

Identification of novel proteins induced by estradiol, 4-hydroxytamoxifen and acolbifene in T47D breast cancer cells

Tamoxifen is currently used as adjuvant therapy for estrogen receptor (ER) positive breast cancer patients and as a chemopreventative agent. Although ER is a predictive marker for tamoxifen response, ER status fails to predict tamoxifen response in a significant number of patients highlighting the need to identify new pathways for tamoxifen sensitivity/resistance. To identify novel proteins induced by tamoxifen in breast cancer cells sensitive to tamoxifen growth inhibition, two-dimensional (2D) gel electrophoresis was used to profile proteins in T47D breast cancer cells. Six proteins were identified that were differentially regulated by 17beta-estradiol, 4-hydroxytamoxifen and the pure antagonist acolbifene (EM-652); calreticulin, synapse associated protein 1 (SYAP1), CD2 antigen binding protein 2 (CD2BP2), nucleosome assembly protein 1 like 1 (NAP1L1), d-3-phosphoglycerate dehydrogenase (3-PHGDH) and pyridoxine 5' phosphate oxidase (PNPO). At the mRNA level, these ligands differentially regulated expression of mRNAs encoding the identified proteins in T47D and MCF7 cells but had no effect on mRNA in ERalpha-negative MDA-MB-231 breast cancer cells. These novel SERM-regulated proteins may participate in new or existing pathways for sensitivity or resistance to SERMs.

Growth inhibition and induction of apoptosis in MCF-7 breast cancer cells by fermented soy milk

The effect of a fermented soy milk product (FSP) on various human breast carcinoma cell lines was investigated, and it was shown to have a growth-inhibitory effect, especially on MCF-7 cells. Thus the MCF-7 cell line was used to study the mechanism of action. In female severe combined immune deficiency mice implanted with MCF-7 cells, pretreatment with FSP significantly inhibited tumor growth. The inhibitory effect of FSP on MCF-7 cells seemed to be caused by the additive effects of a wide variety of constituents. The active components of FSP are mainly in the water phase, and the lipid-soluble fraction, which includes the soy isoflavones such as genistein and daidzein, is relatively ineffective. A variety of methods were used to demonstrate that FSP caused apoptotic cell death in MCF-7 cells. FSP induced generation of reactive oxygen species (ROS). Growth inhibition and ROS generation induced by FSP could be inhibited by catalase and deferoxamine, indicating that the ROS production probably was the cause of this apoptotic cell death. This study suggests that FSP retards tumor growth in vivo and can trigger apoptosis in vitro. It may, therefore, be a potential nutritional supplement in chemotherapy.

Human-SCID mouse chimeric models for the evaluation of anti-cancer therapies

The ability to engraft human tumors and human immunocompetent cells successfully in severe combined immunodeficient (SCID) mice has spawned the development and use of human-mouse chimeric models to evaluate anti-cancer therapies. The lack of standardization and many other potential pitfalls have contributed to the current controversy surrounding the reliability of these different models. Five frequently used SCID mouse models and their specific applications are summarized with the specific aim of providing an objective discussion of the strengths and limitations of each model, together with suggestions for overcoming some of the variabilities and for improving the design and use of future models.

Effect of administration route on FES uptake into MCF-7 tumors

We have observed that intraperitoneal administration of [(18)F]fluoroestradiol (FES), a radiolabeled estrogen receptor ligand, results in higher abdominal organ uptake and slower blood clearance than intravenous administration in female mice. In SCID mice bearing MCF-7 human tumors SC, IP administration resulted in tumor uptake that was only about one third that obtained with IV administration. Thus, the route of administration of a radiopharmaceutical for imaging or radiotherapy of a tumor in the abdomen, an ovarian tumor, for example, could have a profound effect on the efficiency and selectivity of delivery of the agent to the tumor.

Granulocyte-macrophage colony-stimulating factor and B7-2 combination immunogene therapy in an allogeneic Hu-PBL-SCID/beige mouse-human glioblastoma multiforme model

Glioblastoma multiforme is the most common primary central nervous system neoplasm. Its dismal prognosis has led to investigation of new treatment strategies such as immunogene therapy. We transduced the human glioblastoma cell line D54MG in vitro with genes encoding the proinflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF), the T cell co-stimulatory molecule B7-2, or both (in a bicistronic vector) via retroviral vectors. Therapeutic gene expression by D54MG was high after transduction and selection (30 ng/10(6) cells/day for GM-CSF and > 2 orders of magnitude fluorescence shift on flow cytometry for B7-2). The effect of GM-CSF and/or B7-2 transduction on D54MG tumor growth in vivo was monitored in a novel allogeneic human peripheral blood lymphocyte-severe combined immunodeficiency mouse (Hu-PBL-SCID) model. GM-CSF- or B7-2-transduced tumors showed growth suppression in hu-PBL-reconstituted mice compared to untransduced and/or unreconstituted controls. Growth suppression was greatest for B7-2. Furthermore, vaccination with irradiated GM-CSF/B7-2-transduced tumor cells markedly inhibited growth of wild-type tumors at distant sites. Thus, this study illustrates a potential gene therapy strategy for glioblastoma multiforme patients using GM-CSF and/or B7-2 transduced tumor vaccines. Although extension of these allogeneic studies to an autologous system is critical, this is the first demonstration of in vivo efficacy of combination GM-CSF and B7-2 immunogene therapy for human glioblastoma multiforme.

Comparative abilities of athymic nude mice and severe combined immune deficient (SCID) mice to accept transplants of induced rat mammary carcinomas: enhanced transplantation efficiency of those rat mammary carcinomas that have elevated expression of neu oncogene

Grafts of primary carcinogen (DMBA)-induced mammary carcinomas from Sprague-Dawley rats have a poor transplantation efficiency in athymic nude mice. Further compromising these mice immunologically via whole-body irradiation and/or splenectomy, or the administration of hormonal growth factors (estrogen and progesterone) to these mice, did not significantly alter transplantation efficiency. Use of strains of mice that are more immune-impaired than the athymic nude mouse, i.e., the athymic nude-beige-XID mouse (T-cell and LAK-cell deficient) or mice with severe combined immune deficiency (SCID) (which lack functional T cells and B cells) also failed to improve transplantation efficiency. In contrast, transplantation efficiency was sharply increased when primary neu-induced rat mammary carcinomas from female Sprague-Dawley rats were used. These mammary carcinomas, unlike the DMBA-induced rat mammary carcinomas, have a very high level of expression of neu; transplantation of these tumors to either athymic nude mice or SCID mice was considerably more efficient. Thus, these data provide evidence that enhanced expression of neu confers heightened efficiency in the transplantation of primary rat mammary carcinomas to immune-deficient mice (athymic-nude or SCID). Increased neu expression was a greater determinant than more compromised immune states in the transplantation of these rat mammary carcinomas. This biological characteristic of neu expression in mammary carcinomas provides new, additional insight into the importance of this oncogene in mammary tumorigenic processes and may explain, at least in part, the reported inverse relationship between human breast carcinoma neu expression and patient prognosis.

Suppression of growth by dietary fish oil of human breast carcinomas maintained in three different strains of immune-deficient mice

It has been reported that high levels of dietary fish (menhaden) oil, compared with corn oil, suppress the growth of MDA-MB231 and MCF-7 human breast carcinomas maintained in female athymic nude (T lymphocyte-deficient) mice. The purpose of this study was to determine whether dietary fish (menhaden) oil, compared with corn oil, can also suppress the growth of these carcinomas when maintained in female beige-XID-athymic nude (T lymphocyte- and NK/LAK cell-deficient) mice and in female severe combined immune-deficient (SCID) mice (total lack of functional T and B lymphocytes). Results clearly show that dietary fish (menhaden) oil can significantly (p < 0.05) suppress the growth of these carcinomas in the beige-XID-athymic nude mouse and the SCID mouse. Such results provide evidence that the growth suppression of MDA-MB231 and MCF-7 human breast carcinomas, induced by dietary fish oil, is not mediated by immune system mechanisms involving T lymphocytes, B lymphocytes, and/or NK/LAK cells.