title: Lectin from green speckled lentil seeds (Lens culinaris) triggered apoptosis in nasopharyngeal carcinoma cell lines.
abstract: BACKGROUND
  The green speckled lentil seed (Lens culinaris) lectin (GSLL) exhibits hemagglutinating activity, and possesses some properties distinct from those of other lentil lectins (e.g., molecular size, biological activities) that deserve further investigation. This study aims to investigate the basic properties (e.g., molecular size, amino acid sequence, sugar specificity) and biological activities (e.g., antiproliferative activity) of GSLL.
  
  
  METHODS
  GSLL was purified by successive fractionation on SP-Sepharose, Affi-gel blue gel, Mono Q, and Superdex 75. The biochemical properties of GSLL were investigated by SDS-PAGE, mass spectrometry, N-terminal amino acid sequencing, and sugar inhibition tests. For the biological activities, purified lyophilized GSLL was sterilized, adjusted to concentrations from 1 to 0 mg/mL (by twofold serial dilution) in Dulbecco's modified Eagle's medium with fetal bovine serum, and examined by using the MTT assay, flow cytometry, and western blotting after treatment of nasopharyngeal carcinoma CNE1 and CNE2 cell lines with the lectin.
  
  
  RESULTS
  GSLL appeared as a 21-kDa band in non-reducing SDS-PAGE. It was composed of two subunits with molecular sizes of 17 and ~4 kDa. It exhibited specificity in binding to glucose and mannose, as well as glucosides and mannosides. Mass spectrometry and N-terminal amino acid sequencing revealed similarity of GSLL to L. culinaris lectin (LcL), especially higher coverage of the β-chain of LcL. A 48-h treatment with GSLL exerted antiproliferative effects on nasopharyngeal carcinoma CNE1 and CNE2 cell lines with significant inhibition at 0.125 mg/mL (P < 0.001) and 1 mg/mL (P = 0.004), respectively, and these effects were attenuated in the presence of glucose and mannose. GSLL induced apoptosis in nasopharyngeal carcinoma CNE1 cells, with detectable phosphatidylserine externalization, mitochondrial depolarization, and cell cycle arrest. Western blot analysis suggested that GSLL triggered the extrinsic apoptotic pathway involving caspase 3, 8, and 9 in CNE1 cells.
  
  
  CONCLUSIONS
  GSLL possessed some different properties from LcL (e.g., lower pI), and increased caspase 3, 8, and 9 activity in CNE1 cells.
authors.affiliation: State Key Laboratory of Respiratory Disease for Allergy at Shenzhen University, School of Medicine, Shenzhen University, Nanhai Ave 3688, 518060 Shenzhen, Guangdong People's Republic of China.
authors.forename: Yau Sang
authors.initials: YS
authors.lastname: Chan
authors.affiliation: State Key Laboratory of Respiratory Disease for Allergy at Shenzhen University, School of Medicine, Shenzhen University, Nanhai Ave 3688, 518060 Shenzhen, Guangdong People's Republic of China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Respiratory Disease for Allergy at Shenzhen University, School of Medicine, Shenzhen University, Nanhai Ave 3688, 518060 Shenzhen, Guangdong People's Republic of China.
authors.forename: Lixin
authors.initials: L
authors.lastname: Xia
authors.affiliation: School of Biomedical Sciences, Lo Kwee Seong Integrated Biomedical Sciences Building, The Chinese University of Hong Kong, Shatin, New Territories Hong Kong, People's Republic of China.
authors.forename: Tzi Bun
authors.initials: TB
authors.lastname: Ng