Carbazole alkaloids from Murraya koenigii trigger apoptosis and autophagic flux inhibition in human oral squamous cell carcinoma cells.
Carbazole alkaloids, a major constituent of Murraya koenigii (L.) Sprengel (Rutaceae), exhibit biological effects such as anticancer activity via the induction of apoptosis, and they represent candidate chemotherapeutic agents. Oral squamous cell carcinoma (OSCC) is the most prevalent cancer of the oral cavity and a growing and serious health problem worldwide. In this study, we investigated the anticancer properties and mechanisms of action of two carbazole alkaloids derived from M. koenigii leaves, mahanine and isomahanine, in the OSCC cell line CLS-354. At 15 μM, mahanine and isomahanine were cytotoxic to CLS-354 cells, triggering apoptosis via caspase-dependent and -independent mechanisms. Autophagosomes, visualised using monodansylcadaverine (MDC) labelling, were numerous in carbazole alkaloid-treated cells. Mahanine and isomahanine markedly induced the expression of the autophagosome marker microtubule-associated protein 1 light chain 3, type II (LC3B-II). Genetic and chemical inhibition of autophagy via silencing of the Autophagy protein 5 gene and exposure to bafilomycin A1 (BafA1), respectively, did not arrest carbazole alkaloid-induced apoptosis, indicating that it occurs independently of autophagic activation. Surprisingly, both carbazole alkaloids caused increased accumulation of p62/sequestosome1 (p62/SQSTM1), with coordinated expression of LC3B-II and cleaved caspase-3, suggesting inhibition of autophagic flux. Our results suggest that inhibition of autophagic flux is associated with carbazole alkaloid-induced apoptosis. Our findings provide evidence of a novel cytotoxic action of natural carbazole alkaloids and support their use as candidate chemotherapeutic agents for the treatment of OSCC.
School of Allied Health Sciences and Public Health, Walailak University, Nakhon Si Thammarat, 80161, Thailand.
Tanyarath
T
Utaipan
Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ramkhamhaeng University, Bangkok, 10240, Thailand.|Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Burapha University, Bangsaen, Chonburi, 20131, Thailand.
Anan
A
Athipornchai
Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ramkhamhaeng University, Bangkok, 10240, Thailand.
Apichart
A
Suksamrarn
School of Allied Health Sciences and Public Health, Walailak University, Nakhon Si Thammarat, 80161, Thailand.
Canussanun
C
Jirachotikoon
School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan, 621010, China.
Xiaohong
X
Yuan
School of Allied Health Sciences and Public Health, Walailak University, Nakhon Si Thammarat, 80161, Thailand.
Monthon
M
Lertcanawanichakul
School of Allied Health Sciences and Public Health, Walailak University, Nakhon Si Thammarat, 80161, Thailand. aonmu@hotmail.com.
Warangkana
W
Chunglok
D000470:Alkaloids; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis; D002294:Carcinoma, Squamous Cell; D045744:Cell Line, Tumor; D029001:Herbal Medicine / Q000379:methods*; D006801:Humans; D009062:Mouth Neoplasms / Q000188:drug therapy*; D032101:Murraya / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*
D000470:Alkaloids; D000970:Antineoplastic Agents
Apoptosis; Autophagy; Carbazole alkaloid; Murraya koenigii; Oral squamous cell carcinoma
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