檳榔子成份中小於1 kDa的小分子如 arecoline 與 hydroxychavicol 已被證實可誘導細胞的凋亡；然而檳榔子大分子成份對細胞的影響則尚未知的。我們過去曾發現水溶性的檳榔子萃取液在 30-100 kDa 的部位 ( 又稱30-100K ) 與檳榔子萃取液可有效誘導幾種不同類型的上皮癌細胞株進行自體吞噬的死亡。在本篇研究裡經由 LC3-I 的裂解與酸性泡的出現等證據，我們進一步證明 30-100K 亦可誘導正常口腔纖維母細胞與周邊白血球( Peripheral blood lymphocytes, PBLs ) 進行自體吞噬。此外，我們也發現30-100K可略微地誘導 OECM-1、CE81T/VGH 與 PBL 中 AMPK 的磷酸化，反之，arecoline 則對此表現出明顯地抑制作用。因此，這兩種誘導自體吞噬與細胞凋亡的檳榔子成份對此激酶有不同的調節作用。另一方面，30-100K主要的組成為醣纇，蛋白質僅佔少量。而 30-100K 的細胞毒性會經由 lysing enzyme、cellulase、glucanase、trypsin、chitinase 與 proteinase K的降解作用而受到抑制，顯示其誘導自體吞噬的因子有可能為蛋白醣 Small molecules ( < 1 kDa) of areca nut ( AN ) like arecoline and hydroxychavicol have been shown to induce apoptosis; however, larger ingredients of AN remains unknown. We previously found that the soluble 30-100 kDa fraction of AN extract ( ANE ) ( 30-100K ) and ANE are capable of inducing autophagic cell death in several types of carcinomas. In this study, we further demonstrated that 30-100K induced autophagy in normal oral fibroblast and peripheral blood lymphocytes ( PBLs ) as evidenced by LC3-I cleavage and/or emergence of acidic vacuoles. The phosphorylation of AMPK was mildly induced but evidently inhibited respectively by 30-100K and arecoline in carcinoma cells of OECM-1 and CE81T/VGH, as well as in PBLs. Thus, the autophagy- and apoptosis-inducing ingredients of AN exhibit distinct regulation on this kinase. On the other hand, 30-100K is mainly composed of carbohydrates and trace amount of proteins (< 4% ). The cytotoxicity of 30-100K was sensitive to lysing enzyme, cellulase, glucanase, trypsin, and proteinase K digestion suggesting the autophagy-inducing factor of 30-100K to be the proteoglycan.
