Peptide-Drug Conjugate Targeting Keratin 1 Inhibits Triple-Negative Breast Cancer in Mice.

Selective delivery of chemotherapy to the tumor site while sparing healthy cells and tissues is an attractive approach for cancer treatment. Carriers such as peptides can facilitate selective tumor targeting and payload delivery. Peptides with specific affinity for the overexpressed cell-surface receptors in cancer cells are conjugated to chemotherapy to afford peptide-drug conjugates (PDCs) that show selective uptake by cancer cells. Using a 10-mer linear peptide (WxEAAYQrFL) called 18-4 that targets and binds breast cancer cells, we designed a peptide 18-4-doxorubicin (Dox) conjugate with high specific toxicity toward triple-negative breast cancer (TNBC) MDA-MB-231 cells and 30-fold lower toxicity to normal breast MCF10A epithelial cells. Here, we elucidate the in vivo activity of this potent and tumor-selective peptide 18-4-Dox conjugate in mice bearing orthotopic MDA-MB-231 tumors. Mice treated with four weekly injections of the conjugate showed significantly lower tumor volumes compared to mice treated with free Dox at an equivalent Dox dose. Immunohistochemical (IHC) analysis of mice tissues revealed that treatment with a low dose of PDC (2.5 mg/kg of Dox equiv) reduced the expression of proliferation markers (PCNA and Ki-67) and increased apoptosis (evidenced by increased caspase-3 expression). At the same dose of free Dox (2.5 mg/kg), the expression of these markers was similar to that of saline treatment. Accordingly, significantly more Dox accumulated in tumors of conjugate-treated mice (7-fold) compared to the Dox-treated mice, while lower levels of Dox were observed in the liver, heart, and lungs of peptide-Dox conjugate-treated mice (up to 3-fold less) than Dox-treated mice. The IHC analysis of keratin 1 (K1), the receptor for peptide 18-4, revealed K1 upregulation in tumors and low levels in normal mammary fat pad and liver tissues from mice, suggesting preferential uptake of PDCs by TNBC to be K1 receptor-mediated. Taken together, our data support the use of a PDC approach to deliver chemotherapy selectively to the TNBC to inhibit tumor growth.

Determination of soy proteins in calabresa sausage by densitometry on gel electrophoresis

Soy proteins are widely employed in meat products. However addition of non-meat proteins in calabresa sausages is not allowed according to the Brazilian legislation and in case of the non-declared addition of this foreign protein in consumed food, it may trigger allergic reactions in some consumers. Polyacrylamide gel electrophoresis (SDS-PAGE) was used for determining soy proteins in calabresa sausages. Fraud simulations were performed adding different concentrations (0%; 0.5%; 1%; 2%; 5%;10%; 20% and 100%) of soy proteins in sausages. The qualitative analysis was not sensitive to detect thelo west concentrations of soy proteins. On the other hand, by using semi-quantitative analysis by means of densitometry of selected protein fractions from soy and porcine meat, the presence of soy proteins could be determined in the all of analyzed concentrations. This methodology could be implemented, without large investments, for conducting quality control of sausages.