Targeting Proliferating Cell Nuclear Antigen (PCNA) as an Effective Strategy to Inhibit Tumor Cell Proliferation

Targeting highly proliferating cells is an important issue for many types of aggressive tumors. Proliferating Cell Nuclear Antigen (PCNA) is an essential protein that participates in a variety of processes of DNA metabolism, including DNA replication and repair, chromatin organization and transcription and sister chromatid cohesion. In addition, PCNA is involved in cell survival, and possibly in pathways of energy metabolism, such as glycolysis. Thus, the possibility of targeting this protein for chemotherapy against highly proliferating malignancies is under active investigation. Currently, approaches to treat cells with agents targeting PCNA rely on the use of small molecules or on peptides that either bind to PCNA, or act as a competitor of interacting partners. Here, we describe the status of the art in the development of agents targeting PCNA and discuss their application in different types of tumor cell lines and in animal model systems.

Multifaceted Roles of GSK-3 in Cancer and Autophagy-Related Diseases

GSK-3 is a ubiquitously expressed serine/threonine kinase existing as GSK-3αand GSK-3βisoforms, both active under basal conditions and inactivated upon phosphorylation by different upstream kinases. Initially discovered as a regulator of glycogen synthesis, GSK-3 is also involved in several signaling pathways controlling many different key functions. Here, we discuss recent advances regarding (i) GSK-3 structure, function, regulation, and involvement in several cancers, including hepatocarcinoma, cholangiocarcinoma, breast cancer, prostate cancer, leukemia, and melanoma (active GSK-3 has been shown to induce apoptosis in some cases or inhibit apoptosis in other cases and to induce cancer progression or inhibit tumor cell proliferation, suggesting that different GSK-3 modulators may address different specific targets); (ii) GSK-3 involvement in autophagy modulation, reviewing signaling pathways involved in neurodegenerative and liver diseases; (iii) GSK-3 role in oxidative stress and autophagic cell death, focusing on liver injury; (iv) GSK-3 as a possible therapeutic target of natural substances and synthetic inhibitors in many diseases; and (v) GSK-3 role as modulator of mammalian aging, related to metabolic alterations characterizing senescent cells and age-related diseases. Studies summarized here underline the GSK-3 multifaceted role and indicate such kinase as a molecular target in different pathologies, including diseases associated with autophagy dysregulation.

Structure Modification of Ethyl p-methoxycinnamate Isolated from Kaempferia galanga Linn. and Citotoxicity Assay of The Products on WiDr Cells

Ethyl p-methoxycinnamate, major ingredient of Kaempferia galanga rhizome, have been reported not only has analgesic – anti inflammatory activities like NSAIDs which inhibited cyclooxygenase, but also inhibit tumor cell proliferation in specimen of mouse epidermis. Therefore, it will be interesting to carry out synthetic studies on the derivates of ethyl p-methoxycinnamate and searching their citotoxic activity on WiDr cell. We wish to report of structure modification on carboxyl moiety of ethyl p-methoxycinnamate and evaluation on their citotoxic activity on WiDr cell. Isolation of ethyl p-methoxycinnamate from Kaempferia galanga rhizome was carried out by percolation with ethanol 96% as solvent. Hydrolysis of ethyl p-methoxycinnamate in basic condition was performed to obtain p-methoxycinnamic acid. Preparation of some thiourea derivates of ethyl p-methoxycinnamate was carried out by microwave irradiation. Citotoxicity assay was carried out by MTT method for 48 h.Modification of carboxyl group of ethyl p-methoxycinnamate to its thiourea form could be carried out by microwave irradiation gave; (E)-3-(4-methoxyphenyl)-N-(phenylcarba- mothioyl)acrylamide (50%); (E)-3-(4-methoxyphenyl)-N-(4-methoxyphenylcarbamothi- oyl)acrylamide (26%) and (E)-3-(4-methoxyphenyl)-N-(4-methylphenylcarbamothioyl) acrylamide (54%), yield calculated for 2 step from the acid chloride. All compounds showed no citotoxic effect on WiDr cell at 48 h incubation.Keywords : ethyl p-methoxycinnamate, microwave irradiation, Kaempferia galanga, citotoxicity, WiDr cell