Downregulation of chemokine (C­C motif) ligand 5 induced by a novel 8­hydroxyquinoline derivative (91b1) suppresses tumor invasiveness in esophageal carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a particularly aggressive form of cancer with high mortality. In the present study, a novel 8­hydroxyquinoline derivative (91b1) was investigated for its anticancer activities in ESCC along with its associated mechanisms. The in vitro cytotoxic effect of 91b1 were evaluated across five ESCC cell lines using MTS assay, with cisplatin serving as a comparative standard. Changes in gene expression profile were identified by cDNA microarray and further validated by qualitative PCR and immunostaining. Additionally, protein levels of the most notably downregulated target in archival ESCC samples were also studied. 91b1 demonstrated comparable anticancer effect with cisplatin. Notably, chemokine ligand 5 (Ccl5) was identified as the most substantially downregulated gene, with its suppression at both mRNA and protein expression in ESCC cells, exhibiting a dose­dependent manner. The recombinant human protein of CCL5 enhanced the invasion of ESCC cells using the Transwell assay. The upregulation of CCL5 protein was also detected in 50% of ESCC cell lines. CCL5 was also overexpressed in 76.9% of ESCC specimens. The overall results indicated that 91b1 could effectively induce anticancer effect on ESCC cells through downregulating CCL5 expression with suppression of tumor invasion. Overall, these findings suggested that 91b1 effectively inhibited ESCC cell proliferation and tumor invasion by downregulating CCL5 expression, highlighting its potential as a therapeutic agent for ESCC treatment.

Site-specific Labeling of a Protein Lysine Residue By Novel Kinetic Labeling Combinatorial Libraries.

The first example of a kinetic labeling library designed to enable the discovery of affinity labels is presented. Each library component (1) consists of a variable peptidyl component linked to a biotinyl moiety by a 4-mercaptobenzoyl linker in thioester format. We demonstrate that an affinity label can be uncovered by measuring reaction rates between library pools and the protein target, human serum albumin (HSA) and identifying significant outliers. By choosing peptide functionality compatible with a potentially reactive thioester labeling entity, libraries can be screened in pools. It is noteworthy that a limited subset of amino acids (R, S, E, F, Y, l, M, W, and Q) that compose the affinity moiety is sufficient to produce rate variances that guide the discovery process. After two rounds of deconvolution, J-FLYEE-NH2 (7-E) emerges as a bona fide affinity label of HSA. Unlike known affinity labels, the affinity moiety is not retained in the protein product, but is extruded upon acylation of the protein. This feature affords a method of introducing various payloads, without extraneous elements, onto protein frameworks.