A role for CBFβ in maintaining the metastatic phenotype of breast cancer cells

Epithelial to mesenchymal transition (EMT) is a dynamic process that drives cancer cell plasticity and is thought to play a major role in metastasis. Here we show, using MDA-MB-231 cells as a model, that the plasticity of at least some metastatic breast cancer cells is dependent on the transcriptional co-regulator CBFβ. We demonstrate that CBFβ is essential to maintain the mesenchymal phenotype of triple-negative breast cancer cells and that CBFβ-depleted cells undergo a mesenchymal to epithelial transition (MET) and re-organise into acini-like structures, reminiscent of those formed by epithelial breast cells. We subsequently show, using an inducible CBFβ system, that the MET can be reversed, thus demonstrating the plasticity of CBFβ-mediated EMT. Moreover, the MET can be reversed by expression of the EMT transcription factor Slug whose expression is dependent on CBFβ. Finally, we demonstrate that loss of CBFβ inhibits the ability of metastatic breast cancer cells to invade bone cell cultures and suppresses their ability to form bone metastases in vivo. Together our findings demonstrate that CBFβ can determine the plasticity of the metastatic cancer cell phenotype, suggesting that its regulation in different micro-environments may play a key role in the establishment of metastatic tumours.

Abstract 2877: Exercise, alone and in combination with a whole tumor cell vaccine reduces mammary tumor cell growth and enhances anti-tumor immunity

Regular, moderate exercise (EX) can reduce both the incidence and recurrence of breast cancer (BC), and improve survival. Numerous biological mechanism(s) have been proposed to explain these beneficial clinical effects of EX. However, little work has been done to examine the effect of EX on immunomodulation, i.e. the balance between anti-tumor immunity and the emergence of immunosuppressive cells, in particular myeloid derived suppressor cells (MDSC). We have previously demonstrated that moderate EX significantly enhances antigen-specific CD4+ and CD8+ T cell responses and reduces regulatory T cell function in tumor free-mice. Thus, the goal of the current study was to determine if EX could enhance effector function and reduce immunosuppression in tumor bearing mice, and determine if there were any synergistic effects of EX and the administration of a whole tumor cell vaccine on the aforementioned outcomes. Female Balb/c mice were randomized into EX or sedentary control (SED) groups (n = 14-16/group) and had access to running wheel or standard cages, respectively, for 12 weeks prior to the injection of 5×10^4 lucerifase-transfected 4T1.2 tumor cells into the 4th mammary fat pad. Mice were further randomized into vaccination (n = 6-8/group) or vehicle control (n = 4/group) and administered 1×10^6 irradiated 4T1.2 cells (VAC) or HBSS (VEH) at day 7, 14, 21, and 28 post tumor injection. All mice were fed the AIN-76A diet; however, the EX mice (n = 14) were fed 90% of caloric intake of SED animals to remain in energy balance (prevent weight gain) over the course of the study. Primary tumor growth was quantified, and at sacrifice (day 35) organs were collected to assess the following endpoints: splenic antigen-specific CD8+ effector function and myeloid derived suppressor cell (MDSC) accumulation, and metastatic burden in femurs. EX mice, with or without vaccine, weighed significantly less than SED mice (p<0.001). There was a significant effect of both vaccination and EX on primary tumor growth (F(24,200) = 7.386, p<0.001), splenic IFN-γ production (KW = 11.43, p = 0.010); and the accumulation of MDSC (F(3,28) = 6.486, p = 0.021). However, there was only an EX effect on metastatic burden (p = 0.027). There was a synergistic effect of the combination of vaccine+EX on tumor growth, but no other endpoint. These results demonstrate that exercise alone (i.e. in a prevention model, 12 weeks prior to tumor implantation) is highly effective in reducing primary tumor growth and metastases in an aggressive tumor, and significantly shifted the balance of effector and immunosuppressive factors in the direction of anti-tumor immunity. Furthermore, these results demonstrate that exercise is a viable intervention that may yield significant clinical benefit when used in combination with therapeutic cancer vaccines. This work is supported by internal PSU pilot funds for CJR; T32AI074551-03 for WJT.

Citation Format: William J. Turbitt, Donna Sosnoski, Andrea Mastro, Connie Rogers. Exercise, alone and in combination with a whole tumor cell vaccine reduces mammary tumor cell growth and enhances anti-tumor immunity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2877. doi:10.1158/1538-7445.AM2015-2877

A multicentric phase II clinical trial on intra-arterial hepatic radiotherapy with 90yttrium SIR-spheres in unresectable, colorectal liver metastases refractory to i.v. chemotherapy: preliminary results on toxicity and response rates

BACKGROUND

In patients locally progressing after two lines of chemotherapy, some locoregional approaches showed encouraging results in terms of local control of disease. The aim of our study was to evaluate toxicity, clinical response and quality of life in 48 patients with unresectable colorectal liver metastases submitted to selective internal radiotherapy (SIRT).

MATERIALS AND METHODS

Up to now 35 patients with unresectable colorectal liver metastases, refractory to two lines of chemotherapy, underwent intra-arterial infusion of resin microspheres with yttrium-90 (SIR-spheres). Pre-treatment evaluation included a CT scan, blood tests, a PET scan and arteriography of celiac trunk, hepatic and superior mesenteric artery; extrahepatic uptakes and pulmonary shunts more than 10% were excluded by a Scinti-scan. The gastroduodenal artery was embolized before the SIR-spheres injection. Other exclusion criteria were liver dysfunction and anatomical vascular anomalies. The clinical response was evaluated by CT-scan following the RECIST criteria. Median follow-up was 4 months.

RESULTS

Median number of metastases was 4 (range, 1-15), 38% of cases presenting hepatic involvement < 25%. The median SIRT dose delivered was 1.7 GBq. Median pulmonary shunt was 6%. No operative mortality occurred; early toxicity (within 48 hours) was 20.6%, shown as fever, acute pain and leucocytosis. The late toxicity was 24.1% with chronic pain, jaundice and nausea being the most frequent. All the toxic events were graded 2 or 3 according to the WHO scale. Preliminary results were available in terms of clinical response after 6 weeks: 12.5% had a partial response, 75% a stable disease, while progression of disease, was observed in 12.5% of the patients.

CONCLUSION

SIRT is a safe treatment in terms of acute and late toxicity. Intra-arterial microspheres could represent a good therapeutic option for patients with progressing liver metastases only, after two lines of systemic chemotherapy.

Immune function is impaired in iron-deficient, homebound, older women

BACKGROUND

Aging is often associated with a dysregulation of immune function. Iron deficiency may further impair immunity in older adults. Published reports on iron deficiency and immune response in humans are inconsistent. Most studies are focused on young children in developing countries and are often confounded by comorbid conditions, infections, and nutrient deficiencies.

OBJECTIVE

Our objective was to determine the relation of iron status with immune function in homebound older women, who often have impairments in both iron status and immune response. The subjects were selected according to rigorous exclusion criteria for disease, infection, and deficiencies in key nutrients known to affect immunocompetence.

DESIGN

Seventy-two homebound elderly women provided blood for comprehensive evaluation of iron status and cell-mediated and innate immunity. Women were classified as iron-deficient or iron-sufficient on the basis of multiple abnormal iron status test results. Groups were compared with respect to lymphocyte subsets, phagocytosis, oxidative burst capacity, and T cell proliferation upon stimulation with mitogens.

RESULTS

In iron-deficient women, T cell proliferation upon stimulation with concanavalin A and phytohemagglutinin A was only 40-50% of that in iron-sufficient women. Phagocytosis did not differ significantly between the 2 groups, but respiratory burst was significantly less (by 28%) in iron-deficient women than in iron-sufficient women.

CONCLUSIONS

Iron deficiency is associated with impairments in cell-mediated and innate immunity and may render older adults more vulnerable to infections. Further prospective studies using similar exclusion criteria for disease, infection, and concomitant nutrient deficiencies are needed for simultaneous examination of the effects of iron deficiency on immune response and morbidity.

Influence of muscle strength and total work on exercise-induced plasma growth hormone isoforms in women

The purpose of this investigation was to determine the influence of physical strength and the ability to do more total work on human growth hormone (GH) variants to a heavy resistance exercise protocol in untrained women. From a distribution of 100 healthy, untrained women, the strongest 10 women (S) and the weakest 10 women (W) were compared for GH responses pre- and post an acute heavy resistance exercise test (AHRET, 6 sets of 10 RM squats, 2 minutes rest between sets). Blood samples were obtained pre-exercise and immediately post-exercise and subsequently analysed in total as well as fractionated by Sephacryl S-100R column chromatography into three molecular weight size classes: fraction A: > 60 kD, fraction B: 30-60 kD, fraction C: < 30 kD. For each total sample as well as each fraction, immunoreactive GH was measured via the Nichols IRMA, while bioactive GH was measured via the hypox rat tibial line bioassay and Diagnostic Systems Laboratory's immunofunctional GH ELISA. No exercise-induced changes or differences between groups were observed in the tibial line bioassay. However, the S group displayed a significantly higher pre-exercise resting value in the total fraction than the W group. Conversely, the W group exhibited a significantly higher pre-exercise value in the smaller molecular weight fraction C. With regards to the immunofunctional and immunoreactive assays, the total fraction, fraction A, and fraction B demonstrated significant (P < or = 0.05) exercise-induced increases in both the S and W group despite no group differences. For the Nichols and immunofunctional assays significant exercise-induced changes were observed in the smaller molecular weight C fraction in the W group but not the S group. However, the S group displayed a significantly higher pre-exercise value in fraction C relative to the W group. These data demonstrate for the first time that differences exist in the GH molecular weight variants between strong and weak untrained women, with the lower molecular weight variants seemingly less responsive to greater amounts of exercise in stronger women, thus suggesting differential regulation of GH molecular weight variants during resistance exercise due to pre-existing physical parameters.

The isolation and properties of the dimeric subunit of concanavalin A

Concanavalin A (Con A) was dissociated into dimeric and monomeric subunits by incubation at 37 degrees C in acetate buffer of pH 3.8 containing 0.5% sodium dodecyl sulfate. The dimer was isolated in pure form by a density gradient ultracentrifugation method. Several properties of the dimer were determined including the formation of a precipitin with anti-Con A antibodies, the molecular weight, the lack of a binding site for glycogen, the lack of mitogenic activity for spleen lymphocytes, and the lack of inhibition by alpha-methyl D-glucoside. The latter findings differ from results reported by other investigators.

Detection of high mobility group I HMGI(Y) protein in the diagnosis of thyroid tumors: HMGI(Y) expression represents a potential diagnostic indicator of carcinoma

Hyperplastic or neoplastic proliferative lesions of thyroid follicular epithelium consist of a spectrum, ranging from nodular hyperplasia to undifferentiated (anaplastic) carcinoma, and usually present as palpable thyroid nodules. Thyroid nodules are a common occurrence in the general population, but only a small proportion of them are eventually diagnosed as carcinoma. The difficulty in objectively identifying those thyroid nodules that are malignant to avoid unnecessary surgery, combined with the range and effectiveness of the available therapeutic options in those patients who do, indeed, have thyroid carcinoma, has prompted the search for tumor markers and prognostic indicators. The high mobility group I (HMGI) proteins represent a class of nuclear proteins involved in the regulation of chromatin structure and function. HMGI(Y), one of the members of this class, is expressed at high levels during embryogenesis and in malignant tumors but at generally low levels in normal adult human tissues. Previous work on a limited number of thyroid samples suggested that the detection of the HMGI(Y) proteins may provide a clinically useful diagnostic tool. To verify this assumption, we analyzed HMGI(Y) expression by a combination of immunohistochemistry and reverse transcription-PCR in 358 thyroid tissue samples that were representative of the spectrum of thyroid tumor pathology. HMGI(Y) was detectable in 18 of 19 follicular carcinomas, 92 of 96 papillary carcinomas, and 11 of 11 undifferentiated (anaplastic) carcinomas but in only 1 of 20 hyperplastic nodules, 44 of 200 follicular adenomas, and 0 of 12 normal tissue samples. The correlation between HMGI(Y) expression and a diagnosis of carcinoma was highly significant (P < 0.0001). We also prospectively collected and analyzed for HMGI(Y) expression by immunohistochemistry and reverse transcription-PCR in 12 fine needle aspiration biopsies from 10 patients who subsequently underwent surgical removal of a solitary thyroid nodule. HMGI(Y) was detectable only in the four fine needle aspiration biopsies, corresponding to the thyroid nodules that were definitively diagnosed as carcinomas after surgery (two follicular carcinomas and two papillary carcinomas). The remaining eight samples (six follicular adenomas and two samples consisting of normal follicular cells) were negative. The findings of this study confirm the differential expression of HMGI(Y) in thyroid neoplasia and indicate the HMGI(Y) protein as a potential marker for thyroid carcinoma.

RET/PTC oncogene activation is an early event in thyroid carcinogenesis

RET/PTC oncogene activation occurs in about 20% of human thyroid papillary carcinomas. However, it is not known yet whether it is an early or late event in the process of thyroid carcinogenesis. Here we demonstrate, by using a combined immunohistochemical and reverse transcriptase-polymerase chain reaction based approach, that RET/PTC activation is present in 11 out of 26 occult thyroid papillary carcinomas analysed. Therefore, we conclude that it represents an early event in the process of thyroid cell transformation.

Immune changes in test animals during spaceflight

Over the past two decades, it has become apparent that changes in immune parameters occur in cosmonauts and astronauts after spaceflight. Therefore, interest has been generated in the use of animal surrogates to better understand the nature and extent of these changes, the mechanism of these changes, and to allow the possible development of countermeasures. Among the changes noted in animals after spaceflight are alterations in lymphocytic blastogenesis, cytokine function, natural killer cell activity, and colony-stimulating factors. The nature and significance of spaceflight-induced changes in immune responses will be the focus of this review.

The effects of age and oestrone treatment on DNA polymerase activity in anterior pituitary glands of male rats

DNA polymerase activity was found in the cytoplasmic fraction and in isolated nuclei from anterior pituitary glands of male rats. The enzyme activity was assayed by measuring the incorporation of [3H]dTTP into DNA in a medium containing Tris-HCl buffer (pH 8·5), the four deoxyribonucleoside triphosphates, Mg2 +, ATP and activated calf thymus DNA. The DNA polymerase activity decreased with age in glands from animals aged 25 days to over a year but increased after oestrone treatment in vivo. These changes in activity, more pronounced in the cytoplasmic fraction than in the isolated nuclei, were similar to changes in DNA synthesis measured in anterior pituitary glands under the same physiological conditions.

Isolated nuclei also retained endogenous DNA synthetic activity in the absence of added template. Addition of a cytoplasmic fraction to the reaction medium stimulated activity by as much as 1·9-fold but the degree of stimulation was the same whether the cytoplasm was from young, old or oestrone-treated animals.

DNA synthesis in the anterior pituitary of the male rat: effect of castration and photoperiod

Castration increased incorporation of tritiated thymidine into total DNA in the anterior pituitary gland. Furthermore, there was a threefold increase in the percentage of labeled basophils 1 month after castration. Exposure of rats to constant light or dark also changed DNA synthesis; these changes depended on age of the animal and on exposure length. The results reflect physiologically induced mitotic activity in specific classes of pituitary cells and further suggest that neuroendocrine mechanisms may be involved in control of cell turnover in the gland.