Antisense inhibition of survivin expression as a cancer therapeutic.

Survivin, a family member of the inhibitor of apoptosis proteins that is expressed during mitosis in a cell cycle-dependent manner and localized to different components of the mitotic apparatus, plays an important role in both cell division and inhibition of apoptosis. Survivin is expressed in a vast majority of human cancers, but not in normal adult tissues. Survivin expression is often correlated with poor prognosis in a wide variety of cancer patients. These features make survivin an attractive target against which cancer therapeutics could be developed. We have identified a survivin antisense oligonucleotide (ASO) that potently downregulated survivin expression in human cancer cells derived from lung, colon, pancreas, liver, breast, prostate, ovary, cervix, skin, and brain as measured by quantitative RT-PCR and immunoblotting analysis. Specific inhibition of survivin expression in multiple cancer cell lines by this ASO (LY2181308) induced caspase-3-dependent apoptosis, cell cycle arrest in the G(2)-M phase, and multinucleated cells. We also showed that inhibition of survivin expression by LY2181308 sensitized tumor cells to chemotherapeutic-induced apoptosis. Most importantly, in an in vivo human xenograft tumor model, LY2181308 produced significant antitumor activity as compared with saline or its sequence-specific control oligonucleotide and sensitized to gemcitabine, paclitaxel, and docetaxel. Furthermore, we showed that this antitumor activity was associated with significant inhibition of survivin expression in these xenograft tumors. On the basis of these, LY2181308 is being evaluated in a clinical setting (Phase II) in combination with docetaxel for the treatment of prostate cancer.

1,7-annulated indolocarbazoles as cyclin-dependent kinase inhibitors.

The synthesis and kinase inhibitory activity of a series of novel 1,7-annulated indolocarbazoles 6 and 16 is described. These compounds exhibited potent inhibitory activity against cyclin-dependent kinase 4 and good antiproliferative activity in a human colon carcinoma cell line.

The discovery of a new structural class of cyclin-dependent kinase inhibitors, aminoimidazo[1,2-a]pyridines.

The protein kinase family represents an enormous opportunity for drug development. However, the current limitation in structural diversity of kinase inhibitors has complicated efforts to identify effective treatments of diseases that involve protein kinase signaling pathways. We have identified a new structural class of protein serine/threonine kinase inhibitors comprising an aminoimidazo[1,2-a]pyridine nucleus. In this report, we describe the first successful use of this class of aza-heterocycles to generate potent inhibitors of cyclin-dependent kinases that compete with ATP for binding to a catalytic subunit of the protein. Co-crystal structures of CDK2 in complex with lead compounds reveal a unique mode of binding. Using this knowledge, a structure-based design approach directed this chemical scaffold toward generating potent and selective CDK2 inhibitors, which selectively inhibited the CDK2-dependent phosphorylation of Rb and induced caspase-3-dependent apoptosis in HCT 116 tumor cells. The discovery of this new class of ATP-site-directed protein kinase inhibitors, aminoimidazo[1,2-a]pyridines, provides the basis for a new medicinal chemistry tool to be used in the search for effective treatments of cancer and other diseases that involve protein kinase signaling pathways.

Novel, potent and selective cyclin D1/CDK4 inhibitors: indolo[6,7-a]pyrrolo[3,4-c]carbazoles.

The synthesis and CDK inhibitory properties of a series of indolo[6,7-a]pyrrolo[3,4-c]carbazoles is reported. In addition to their potent CDK activity, the compounds display antiproliferative activity against two human cancer cell lines. These inhibitors also effect strong G1 arrest in these cell lines and inhibit Rb phosphorylation at Ser780 consistent with inhibition of cyclin D1/CDK4.