Klavuzons are 6-(naphthalen-1-yl) substituted 5,6-dihydro-2H-pyran-2-one derivatives showing promising antiproliferative activities in variety of cancer cell lines. In this work, racemic syntheses of nine novel 4'-alkyl substituted klavuzon derivatives were completed in eight steps and anticancer properties of these compounds were evaluated. It is found that size of the substituent has dramatic effect over the potency and selectivity of the cytotoxic activity in cancerous and healthy pancreatic cell lines. The size of the substituent can also effect the CRM1 inhibitory properties of klavuzon derivatives. Strong cytotoxic activity and CRM1 inhibition can be observed only when a small substituent present at 4'-position of naphthalen-1-yl group. However, these substituents makes the molecule more cytotoxic in healthy pancreatic cells rather than cancerous pancreatic cells. Among the tested compounds 1,2,3,4-tetrahydrophenanthren-9-yl substituted lactone was the most cytotoxic compound and its antiproliferative activity was also tested in 3D spheroids generated from HuH-7 cell lines.

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There are 4 different sialidases that have been described in humans: lysosomal (Neu1), cytoplasmic (Neu2), plasma membrane (Neu3), and lysosomal/mitochondrial (Neu4). Previously, we have shown that Neu4 has a broad substrate specificity and is active against glyco-conjugates, including G M2 ganglioside, at the acidic pH of 3.2. An overexpression of Neu4 in transfected neuroglia cells from a Tay-Sachs patient shows a clearance of accumulated G M2 , indicating the biological importance of Neu4. In this paper, we aimed to characterize a minimal promoter region of the human Neu4 gene in order to understand the molecular mechanism regulating its expression. We cloned 7 different DNA fragments from the human Neu4 promoter region into luciferase expression vectors for a reporter assay and also performed an electrophoretic mobility shift assay to demonstrate the binding of transcription factors. We demonstrated that -187 bp upstream of the Neu4 gene is a minimal promoter region for controlling transcription from the human Neu4 gene. The electrophoretic mobility shift assay showed that the minimal promoter region recruits a c-myc transcription factor, which might be responsible for regulation of Neu4 gene transcription. The data we obtained might be useful to discover small molecules, which control selective high expression of the human Neu4 gene, resulting in the normal morphological phenotype in the lysosomes of Tay-Sachs patients.