Cancer--Molecular aspects.

Model
Digital Document
Publisher
Florida Atlantic University
Description
Studies have shown that tumor cells are susceptible to pharmacological targeting
of their altered glycolytic metabolism with a variety of compounds that result in
apoptosis. One such compound, 3-bromopyruvate (3-BP), has been shown to eradicate
cancer in an animal model. However, no studies have shown whether the apoptotic
fragments resulting from 3-BP treatment have the capacity to elicit an immunogenic cell
death that activates dendritic cells, the primary antigen presenting cell in the immune
system. Immunogenic cell death is critical to eliciting an effective adaptive immune
response that selectively kills additional target cells and generates immunological
memory. We demonstrated that 3-bromopyruvate induced apoptosis in a number of
different murine breast cancer cell lines, including the highly metastatic 4T1 line. The
dying tumor cells stimulated immature dendritic cells (DCs) of the immortal JAWS II
cell line to produce high levels of the pro-inflammatory cytokine IL-12, and increased their expression of key co-stimulatory molecules CD80 and CD86. The activated
dendritic cells showed increased uptake of fragments from dying tumor cells that
correlated with the increased levels of calreticulin on the surface and release of high
group motility box 1 (HMGB1) of the latter following 3-BP treatment. Additionally, the
anti-phagocytic signal CD47 present on breast cancer cells was reduced by treatment with
3-bromopyruvate when compared to the levels on untreated 4T1 cells. 3-BP treated breast
cancer cells were able to activate dendritic cells through TLR4 signaling. Signaling was
dependent on both the expression of surface calreticulin and on the extracellular release
of high mobility group box 1 protein (HMGB1) during the process of immunogenic cell
death. Killing by 3-BP was compared to mitoxantrone and doxorubicin, among the few
chemotherapeutics that induce immunogenic cell death. 3-BP killing was likewise
compared to camptothecin, a compound that fails to induce immunogenic cell death.
Importantly, 3-BP did not markedly decrease the levels of the key peptide presenting
molecule MHC I on DCs that were co-cultivated with dying tumor cells. Treatment of the
highly aggressive triple negative BT-20 human breast cancer cell line with 3-BP also
induced an immunogenic cell death, activating human dendritic cells in vitro.
Model
Digital Document
Publisher
Florida Atlantic University
Description
Extracellular stimuli may influence the M1/M2 phenotypic polarization of
macrophages. We examined M1/M2 biomarkers, phagocytic activity, and tumoricidal
activity in RAW 264.7 mouse macrophages. Macrophages were treated with conditioned
media (CM) from 4T1 breast cancer cells, curcumin, 22-oxacalcitriol, LPS, or a
combination of the previously listed. Arginase activity, a M2 phenotypic biomarker, was
upregulated by the treatment of macrophages with conditioned media. Curcumin, 22-
oxacalcitriol, and LPS partially inhibited RAW 264.7 arginase activity in the presence of
4T1 breast cancer media. 22-oxacalcitriol increased the phagocytic ability of RAW 264.7
macrophages in the presence of M2 polarizing substances produced by the 4T1 breast
cancer cells. Also, LPS increased RAW 264.7 phagocytic ability in the presence of 4T1
breast cancer CM. This study looked at the potential substances that would possibly reverse the M2 tumor promoting macrophage phenotype seen in the breast cancer tumor
environment.