Margarette Bryan

Gap Junction–Mediated Import of MicroRNA from Bone Marrow Stromal Cells Can Elicit Cell Cycle Quiescence in Breast Cancer Cells

Bone marrow (BM) metastasis of breast cancer (BC) can recur even decades after initial diagnosis and treatment, implying the long-term survival of disseminated cancer cells in a dormant state. Here we investigated the role of microRNAs (miRNA) transmitted from BM stroma to BC cells via gap junctions and exosomes in tumor cell quiescence. MDA-MB-231 and T47D BC cells arrest in G(0) phase of the cell cycle when cocultured with BM stroma. Analyses of miRNA expression profiles identified numerous miRNAs implicated in cell proliferation including miR-127, -197, -222, and -223 targeting CXCL12. Subsequently, we showed that these CXCL12-specific miRNAs are transported from BM stroma to BC cells via gap junctions, leading to reduced CXCL12 levels and decreased proliferation. Stroma-derived exosomes containing miRNAs also contributed to BC cell quiescence, although to a lesser degree than miRNAs transmitted via gap junctions. This study shows that the transfer of miRNAs from BM stroma to BC cells might play a role in the dormancy of BM metastases.

Mesenchymal Stem Cells Protect Breast Cancer Cells through Regulatory T Cells: Role of Mesenchymal Stem Cell-Derived TGF-β

Mesenchymal stem cells (MSCs) have been shown to support breast cancer growth. Because MSCs also increase the frequency of regulatory T cells (Tregs), this study tested the hypothesis that human MSCs, via Tregs, protect breast cancer cells (BCCs) from immune clearance MSCs suppressed the proliferation of PBMCs when the latter were exposed to gamma-irradiated BCCs. Similarly, MSCs showed significant inhibition of PBMC migration toward BCCs and a corresponding decrease in CXCL12. MSCs also inhibited NK cell and CTL functions, which correlated with reduced numbers of CD8+ and CD56+ cells compared with parallel cultures without MSCs. The reduced NK and CTL activities correlated with a decrease in intracellular and secreted granzyme B. To explain these immunosuppressive findings, we compared Treg levels after coculture with MSCs and found an ∼2-fold increase in Tregs, with associated decreases in antitumor Th1 cytokines and increases in Th2 cytokines. MSC-derived TGF-β1 was largely responsible for the increase in Tregs based on knockdown studies. In the presence of Treg depletion, PBMC proliferation and effector functions were partially restored. Together, these studies show an MSC-mediated increase in Tregs in cocultures of PBMCs and BCCs. The results could be explained, in part, by the increase in Th2-type cytokines and MSC-generated TGF-β1. These findings demonstrate immune protection by MSCs to BCCs. The reduction in immune cell proliferation and recruitment mediated by MSCs has implications for treatment of breast cancer with chemotherapy.

Mesenchymal Stem Cells in Early Entry of Breast Cancer into Bone Marrow

Background An understanding of BC cell (BCC) entry into bone marrow (BM) at low tumor burden is limited when compared to highly metastatic events during heavy tumor burden. BCCs can achieve quiescence, without interfering with hematopoiesis. This occurs partly through the generation of gap junctions with BM stroma, located close to the endosteum. These events are partly mediated by the evolutionary conserved gene, Tac1. Methodogy/Principal Findings This study focuses on the role of mesenchymal stem cells (MSCs), Tac1, SDF-1 and CXCR4 in BCC entry into BM. The model is established in studies with low numbers of tumor cells, and focuses on cancer cells with low metastatic and invasion potential. This allowed us to recapitulate early event, and to study cancer cells with low invasive potential, even when they are part of larger numbers of highly metastatic cells. A novel migration assay showed a facilitating role of MSCs in BCC migration across BM endothelial cells. siRNA and ectopic expression studies showed a central role for Tac1 and secondary roles for SDF-1α and CXCR4. We also observed differences in the mechanisms between low invasive and highly metastatic cells. The in vitro studies were verified in xenogeneic mouse models that showed a preference for low invasive BCCs to BM, but comparable movement to lung and BM by highly metastatic BCCs. The expressions of Tac1 and production of SDF-1α were verified in primary BCCs from paired samples of BM aspirates and peripheral blood. Conclusions/Significance MSC facilitate BCC entry into BM, partly through Tac1-mediated regulation of SDF-1α and CXCR4. We propose a particular population of BCC with preference for BM could be isolated for characterization. This population might be the subset that enter BM at an early time period, and could be responsible for cancer resurgence and resistance to current therapies.

Delineation of breast cancer cell hierarchy identifies the subset responsible for dormancy

The bone marrow (BM) is a major organ of breast cancer (BC) dormancy and a common source of BC resurgence. Gap junctional intercellular communication (GJIC) between BC cells (BCCs) and BM stroma facilitates dormancy. This study reports on a hierarchy of BCCs with the most immature subset (Oct4hi/CD44hi/med/CD24−/+) demonstrating chemoresistance, dormancy, and stem cell properties: self-renewal, serial passaging ability, cycling quiescence, long doubling time, asymmetric division, high metastatic and invasive capability. In vitro and in vivo studies indicated that this subset was responsible for GJIC with BM stroma. Similar BCCs were detected in the blood of patients despite aggressive treatment and in a patient with a relatively large tumor but no lymph node involvement. In brief, these findings identified a novel BCC subset with stem cell properties, with preference for dormancy and in the circulation of patients. The findings establish a working cellular hierarchy of BCCs based on phenotype and functions.

Mesenchymal Stem Cell–Derived Exosomes Stimulate Cycling Quiescence and Early Breast Cancer Dormancy in Bone Marrow

Dormant breast cancers resurge as metastatic disease after a long dormancy period in the bone marrow, where cancer cells interact with mesenchymal stem cells (MSC). However, the nature of early interactions between breast cancer cells and MSCs in the bone marrow microenvironment that facilitate adaptation to a quiescent state remains poorly understood. Here, we report that breast cancer cells prime MSC to release exosomes containing distinct miRNA contents, such as miR-222/223, which in turn promotes quiescence in a subset of cancer cells and confers drug resistance. Building on these results, we developed a novel, nontoxic therapeutic strategy to target dormant breast cancer cells based on systemic administration of MSC loaded with antagomiR-222/223. In an immunodeficient mouse model of dormant breast cancer, this therapy sensitized breast cancer cells to carboplatin-based therapy and increased host survival. Overall, our findings illuminate the nature of the regulatory interactions between breast cancer cells and MSCs in the evolution of tumor dormancy and resurgence in the micrometastatic microenvironment of the bone marrow. Cancer Res; 76(19); 5832-44. ©2016 AACR.

Phase I Trial of Pegylated Liposomal Doxorubicin with Hyperthermic Intraperitoneal Chemotherapy in Patients Undergoing Cytoreduction for Advanced Intra-abdominal Malignancy

BackgroundCytoreduction coupled with hyperthermic intraperitoneal chemotherapy (HIPEC) is an attractive treatment option for a select group of patients with abdominal-only malignancy. The present phase I study examined the safety and pharmacokinetics of intraperitoneal pegylated liposomal doxorubicin (PLD) used in the context of HIPEC in patients with advanced abdominal-only malignancies.MethodsPatients with advanced abdominal malignancies underwent maximal cytoreduction and HIPEC with escalating doses of PLD (15–100 mg/m2). Perfusate, serum, and tissue doxorubicin levels were measured in five patients undergoing HIPEC at the maximum tolerated dose.ResultsTwenty-one patients were enrolled in this trial. The maximum dose evaluated in this trial was 100 mg/m2 and was well tolerated. The most common grade 3/4 complications were superficial wound infection and prolonged ileus. One patient developed an anastomotic leak in the postoperative period, requiring re-exploration. The median postoperative length of stay was 7 days (range, 4–29 days), three patients required readmissions within 30 days, and there were no operative mortalities The median follow-up time for was 13.7 months (range, 3–38 months). The median overall survival was 30.6 months with a median disease-free survival of 25 months.ConclusionsWe report that HIPEC with PLD following maximal cytoreduction in patients with advanced abdominal-only gastrointestinal or gynecologic malignancies is well tolerated. Encouraging survival after cytoreduction and HIPEC with PLD suggest that a phase II trial to verify activity is indicated.

Phase I/II trial of accutane as a potentiator of carboplatin and paclitaxel in squamous cell carcinomas.

This study investigated the toxicity and efficacy of a 13-cis retinoic acid, carboplatin, and paclitaxel (Taxol) regimen in 18 patients with recurrent or metastatic squamous cell carcinomas (12 head and neck, 4 cervix, 1 esophagus, and 1 anus). Three patients were treated at each dose level with fenretamide (Accutane) 1 mg/kg/d orally for 14 days, carboplatin AUC of 5 mg/ml·min intravenously (IV) and paclitaxel at a dose of 135, 155, 175, 195, 205, or 225 mg/m2 IV on day 8 every 4 weeks for 6 cycles. Fifteen evaluable patients had a total of 72 treatment cycles. There were 21 grade III or IV toxicities distributed among all the dose levels, including neutropenia, anemia, thrombocytopenia, elevated prothrombin time/partial thromboplastin time, elevated alkaline phosphatase, weight loss, alopecia, and three deaths from aspiration pneumonia and septic shock. The maximum tolerated dosage included 205 mg/m2 paclitaxel. There was one complete response, three partial responses, and 2 stable diseases. The three partial responses were in the four patients with cervical cancer. Responses did not correlate with expression of retinoic acid receptor subtypes. Toxicity profiles and overall response rates were comparable to prior studies with similar chemotherapy regimens alone. The data support further study in a phase II trial.

Influence of Prescription Benefits on Reported Pain in Cancer Patients

OBJECTIVE To identify associations between prescription coverage and cancer pain and its sequelae in indigent patients. DESIGN AND SETTING A retrospective chart review at UMDNJ-University Hospital. PATIENTS AND OUTCOME MEASURES Charts from 20 patients with Medicaid and 20 patients categorized as Self-pay/Charity Care were analyzed for the influence of insurance coverage on reported pain at the time of a hospital discharge and at three subsequent clinic visits. Patient and disease characteristics, pain regimens, doses, reported pain and its impact were determined. RESULTS The groups were statistically indistinguishable except for age and ethnicity. The Medicaid group was younger and had a majority of African Americans while the Self-pay/Charity Care patients had a majority of Hispanics. Lower doses of transdermal fentanyl were prescribed to Self-pay/Charity Care patients. Self-pay/Charity Care patients tended to report higher pain levels, but this was statistically significant only at the second clinic visit. The clinical significance of differences in pain intensity was reflected in differences in unscheduled visits and admissions. Adherence to pain regimens improved in the Medicaid group and diminished in the Self-pay/Charity Care group, but the differences did not achieve statistical significance. Lack of funds as the reason for non-adherence was only given by Self-pay/Charity Care patients. CONCLUSION Indigent patients without prescription coverage trended toward reporting more cancer pain, received lower doses of transdermal fentanyl, and trended to lower adherence to pain regimens due to financial reasons. The trends observed in this pilot study will guide the design of a hypothesis-driven regression analysis.

Prescription Coverage in Indigent Patients Affects the Use of Long‐Acting Opioids in the Management of Cancer Pain

PURPOSE We tested the hypothesis that prescription coverage affects the prescribing of long-acting opiates to indigent inner city minority patients with cancer pain. MATERIALS AND METHODS We conducted a chart review of 360 patients treated in the Oncology Practice at University of Medicine and Dentistry of New Jersey University Hospital, who were prescribed opiate pain medications. Half the patients were charity care or self-pay (CC/SP), without the benefit of prescription coverage, and half had Medicaid, with unlimited prescription coverage. We evaluated patients discharged from a hospitalization, who had three subsequent outpatient follow-up visits. We compared demographics, pain intensity, the type and dose of opiates, adherence to prescribed pain regimen, unscheduled emergency department visits, and unscheduled hospitalizations. RESULTS There was a significantly greater use of long-acting opiates in the Medicaid group than in the CC/SP group. The Medicaid group had significantly more African American patients and a greater rate of smoking and substance use, and the CC/SP group disproportionately more Hispanic and Asian patients and less smoking and substance use. Hispanic and Asian patients were less likely to have long-acting opiates prescribed to them. Pain levels and adherence were equivalent in both groups and were not affected by any of these variables except stage of disease, which was equally distributed in the two groups. CONCLUSION Appropriate use of long-acting opiates for equivalent levels of cancer pain was influenced only by the availability of prescription coverage. The group without prescription coverage and receiving fewer long-acting opiates had disproportionately more Hispanic and Asian patients.

Non‐canonical effects of anthrax toxins on haematopoiesis: implications for vaccine development

Anthrax receptor (ATR) shares similarities with molecules relevant to haematopoiesis. This suggests that anthrax proteins might bind to these mimicking molecules and exert non‐specific haematopoietic effects. The haematopoietic system is the site of immune cell development in the adult. As such, ATR ligand, protective antigen (PA) and the other anthrax proteins, lethal factor, edema factor, could be significant to haematopoietic responses against Bacillus anthracis infection. Because haematopoiesis is the process of immune cell development, effects by anthrax proteins could be relevant to vaccine development. Here, we report on effects of anthrax proteins and toxins on early and late haematopoiesis. Flow cytometry shows binding of PA to haematopoietic cells. This binding might be partly specific because flow cytometry and Western blots demonstrate the presence of ATR1 on haematopoietic cell subsets and the supporting stromal cells. Functional studies with long‐term initiating cell and clonogenic assays determined haematopoietic suppression by anthrax toxins and stimulation by monomeric proteins. The suppressive effects were not attributed to cell death, but partly through the induction of haematopoietic suppressors, interleukin (IL)‐10 and CCL3 (MIP‐1α). In summary, anthrax proteins affect immune cell development by effects on haematopoiesis. The type of effect, stimulation or suppression, depend on whether the stimulator is a toxin or monomeric protein. The studies show effects of anthrax proteins beginning at the early stage of haematopoiesis, and also show secondary mediators such as IL‐10 and CCL3. The roles of other cytokines and additional ATR are yet to be investigated.