Endocan as a prognostic biomarker of triple-negative breast cancer.

PURPOSE: Triple-negative breast cancer (TNBC) has aggressive characteristics and fewer treatment options than other subtypes. The purpose of this study was to explore prognostic biomarkers for TNBC that can be easily detected from the blood samples. METHODS: MDA-MB-231 and MDA-MB-231BR, a brain metastatic variant of the human TNBC cell line MDA-MB-231, were used as less and more aggressive models of TNBC, respectively. The extent to which the candidate gene/protein identified by RNA sequencing correlated well with aggressiveness of TNBC and how much protein was detected from the blood of tumor-bearing mice were evaluated. RESULTS: Both the in vitro proliferation and in vivo tumor growth of MDA-MB-231BR were more rapid than those of MDA-MB-231. RNA sequencing identified ESM1 as a gene that was expressed significantly more in MDA-MB-231BR than in MDA-MB-231, and qRT-PCR confirmed a significantly higher expression of ESM1 in MDA-MB-231BR xenograft in vivo. Furthermore, Kaplan-Meier analysis of relapse-free survival demonstrated that TNBC patients with high ESM1 expression had clearly worse relapse-free survival than those with low ESM1 expression, which was consistent with our preclinical findings. Endocan, a protein of ESM1 gene product, was successfully detected in both conditioned medium from MDA-MB-231BR and plasma samples from mice bearing MDA-MB-231BR xenograft, which showed a significantly distinct pattern from less aggressive MDA-MB-231. Moreover, bisulfite sequence analysis revealed that overexpression of ESM1 in MDA-MB-231BR might be attributed to DNA demethylation in an upstream region of the ESM1 gene. CONCLUSION: This study indicates that endocan could be used as a blood-based prognostic biomarker in TNBC patients.

Controlled Secretion of the Anticancer Protein MDA-7 from Engineered Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) have been explored as a "live" carrier of cytokines for targeted cancer therapy, but, in earlier reports in the literature, the secretion process of therapeutic cytokines was not regulated. The purpose of this study was to generate MSCs to conditionally secrete the melanoma differentiation-associated gene-7 (MDA-7) tumor-suppressor protein. To control the secretion of MDA-7 from MSCs, a well-established tetracycline-controlled transcriptional activation system was incorporated into MDA-7 plasmid. MDA-7 gene expression was induced in the engineered MSCs only in the presence of doxycycline, as characterized by quantitative reverse transcription (qRT)-PCR. Enzyme-linked immunosorbent assay (ELISA) also revealed that the MDA-7 protein was secreted from the engineered MSCs only after the cells had been exposed to doxycycline. Both recombinant human MDA-7 protein and the conditioned medium from the engineered MSCs in the presence of doxycycline significantly inhibited tube formation of human umbilical vascular endothelial cells (HUVECs), indicating that our system could be used for targeted, antiangiogenic therapy. Overall, this study provides useful information on the potential use of engineered MSCs for the controlled secretion of therapeutic proteins, in this case MDA-7, for targeted cancer therapy.

High-accuracy current generation in the nanoampere regime from a silicon single-trap electron pump.

A gigahertz single-electron (SE) pump with a semiconductor charge island is promising for a future quantum current standard. However, high-accuracy current in the nanoampere regime is still difficult to achieve because the performance of SE pumps tends to degrade significantly at frequencies exceeding 1 GHz. Here, we demonstrate robust SE pumping via a single-trap level in silicon up to 7.4 GHz, at which the pumping current exceeds 1 nA. An accuracy test with an uncertainty of about one part per million (ppm) reveals that the pumping current deviates from the ideal value by only about 20 ppm at the flattest part of the current plateau. This value is two orders of magnitude better than the best one reported in the nanoampere regime. In addition, the pumping accuracy is almost unchanged up to 7.4 GHz, probably due to strong electron confinement in the trap. These results indicate that trap-mediated SE pumping is promising for achieving the practical operation of the quantum current standard.

Intrinsic Resistance to 5-Fluorouracil in a Brain Metastatic Variant of Human Breast Cancer Cell Line, MDA-MB-231BR.

Although drug resistance is often observed in metastatic recurrence of breast cancer, little is known about the intrinsic drug resistance in such metastases. In the present study, we found, for the first time, that MDA-MB-231BR, a brain metastatic variant of a human breast cancer cell line, was refractory to treatment with 5-fluorouracil (5-FU) even without chronic drug exposure, compared to its parent cell line, MDA-MB-231, and a bone metastatic variant, MDA-MB-231SCP2. Both the mRNA and protein levels of COX-2 and BCL2A1 in MDA-MB-231BR were significantly higher than those in MDA-MB-231 or MDA-MB-231SCP2. Neither the COX-2 inhibitor celecoxib nor the NF-κB inhibitor BAY11-7082 could sensitize MDA-MB-231BR to 5-FU, indicating that COX-2 plays little, if any, role in the resistance of MDA-MB-231BR to 5-FU. Although BCL2-family inhibitor ABT-263 failed to sensitize MDA-MB-231BR to 5-FU at a dose at which ABT-263 is considered to bind to BCL2, BCL2-xL, and BCL2-w, but not to BCL2A1, ABT-263 did sensitize MDA-MB-231BR to 5-FU to a level comparable to that in MDA-MB-231 at a dose of 5 µM, at which ABT-263 may disrupt intracellular BCL2A1 protein interactions. More importantly, BCL2A1 siRNA sensitized MDA-MB-231BR to 5-FU, whereas the overexpression of BCL2A1 conferred 5-FU-resistance on MDA-MB-231. These results indicate that BCL2A1 is a key contributor to the intrinsic 5-FU-resistance in MDA-MB-231BR. It is interesting to note that the drug sensitivity of MDA-MB-231BR was distinct from that of MDA-MB-231SCP2 even though they have the same origin (MDA-MB-231). Further investigations pertinent to the present findings may provide valuable insight into the breast cancer brain metastasis.