The natural product Aristolactam AIIIa as a new ligand targeting the polo-box domain of polo-like kinase 1 potently inhibits cancer cell proliferation.
OBJECTIVE
To search for novel inhibitors of human polo-like kinase 1 (Plk1), which plays important roles in various aspects of mitotic progression and is believed as a promising anti-cancer drug target, and further investigate the potential inhibition mechanism of active compounds against Plk1, thus developing potent anti-tumor lead compounds.


METHODS
Surface plasmon resonance (SPR) technology-based assay and enzymatic inhibition assay were used to screen Plk1 inhibitors. Sulphorhodamine B (SRB)-based assay, flow cytometry, confocal microscopy and Western blotting were used to further identify the potent Plk1 inhibitor. To investigate the inhibitory mechanism of the active compound against Plk1, enzymatic inhibition assay, SPR and yeast two-hybrid technology-based assays were used.


RESULTS
Aristolactam AIIIa was identified as a new type of Plk1 inhibitors, targeting the Polo Box domain (PBD) which is another efficient tactic for exploring Plk1 inhibitors. Further studies indicated that it could block the proliferations of HeLa, A549, HGC and the HCT-8/V cells (clinical Navelbine-resistant cancer cell), induce mitotic arrest of HeLa cells at G2/M phase with spindle abnormalities and promote apoptosis in HeLa cells. The results from SPR and yeast two-hybrid technology-based assays suggested that it could target both the catalytic domain of Plk1 (CD) and PBD and enhance the CD/PBD interaction.


CONCLUSIONS
Our current work is expected to shed light on the potential anti-tumor mechanism of Aristolactam AIIIa, and this natural product might be possibly used as a lead compound for further developing anti-tumor drugs.
School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
Li
L
Li
Xu
X
Wang
Jing
J
Chen
Hong
H
Ding
Yu
Y
Zhang
Tian-Cen
TC
Hu
Li-Hong
LH
Hu
Hua-Liang
HL
Jiang
Xu
X
Shen
D000230:Adenocarcinoma / Q000188:drug therapy / Q000201:enzymology; D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D020134:Catalytic Domain / Q000235:genetics; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019073:HT29 Cells; D006367:HeLa Cells; D006801:Humans; D026121:Indole Alkaloids; D020128:Inhibitory Concentration 50; D007769:Lactams; D007939:Leukemia L1210 / Q000188:drug therapy / Q000201:enzymology; D008024:Ligands; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology; D051379:Mice; D015394:Molecular Structure; D009369:Neoplasms / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D008941:Spindle Apparatus / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000201:enzymology; D020349:Surface Plasmon Resonance; D020798:Two-Hybrid System Techniques; D000097869:Polo-Like Kinase 1
D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D026121:Indole Alkaloids; D007769:Lactams; D008024:Ligands; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1; C546671:Aristolactam AIIIa