title: Soy protein extract (SPE) exhibits differential in vitro cell proliferation effects in oral cancer and normal cell lines.
abstract: Prior research has demonstrated that specific isoflavones derived from soy may exhibit antitumor effects against many cancers, including oral cancer. Most of this prior research involved isolation and testing of individual soy components, such as genistein, daidzein, and glycitein, which exhibit cytotoxicity against cancerous cells but may also have residual cytotoxic effects on normal cells. Few studies have evaluated whole soy extract, containing a combination of these isoflavones, and other bioreactive compounds, which may function synergistically and more effectively against oral cancers. This study compared the antiproliferative effects of whole soy protein extract (SPE) on CAL 27 and SCC25 oral cancer cell lines in vitro. Administration of SPE significantly inhibited oral cancer growth and exerted these effects at lower concentrations compared with another class of flavonoids (proanthocyanidins) that were previously tested on these cell lines. This SPE-induced growth inhibition correlated with down-regulated mRNA expression in the oral cancer cell-cycle promoter ornithine decarboxylase (ODC), as well as upregulation of caspase-2 and caspase-8, initiators and effectors of apoptosis. These results suggest that SPE may represent a potential chemopreventive or chemotherapeutic option for oral cancer. Moreover, SPE may be more effective than other flavonoids currently used and may be effective at lower concentrations that approximate physiologic serum levels (0-2 μmol/l). This study may help to explain why diets rich in fruits, vegetables, and soy protein are associated with protection against development and progression of oral cancers, although further study is needed to develop specific public health recommendations for oral cancer treatment and prevention.
authors.affiliation: Department of Biomedical Sciences, School of Dental Medicine, University of Nevada, Las Vegas, Nevada 89106, USA. karl.kingsley@unlv.edu
authors.forename: Karl
authors.initials: K
authors.lastname: Kingsley
authors.forename: Khanh
authors.initials: K
authors.lastname: Truong
authors.forename: Erik
authors.initials: E
authors.lastname: Low
authors.forename: Charles K
authors.initials: CK
authors.lastname: Hill
authors.forename: Shruti B
authors.initials: SB
authors.lastname: Chokshi
authors.forename: Don
authors.initials: D
authors.lastname: Phipps
authors.forename: M Abigail
authors.initials: MA
authors.lastname: West
authors.forename: Mark A
authors.initials: MA
authors.lastname: Keiserman
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Bergman
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use; D002294:Carcinoma, Squamous Cell / Q000178:diet therapy* / Q000188:drug therapy / Q000378:metabolism; D053143:Caspase 2 / Q000235:genetics / Q000378:metabolism; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology* / Q000627:therapeutic use; D009062:Mouth Neoplasms / Q000178:diet therapy* / Q000188:drug therapy / Q000378:metabolism; D009955:Ornithine Decarboxylase / Q000235:genetics / Q000378:metabolism; D008517:Phytotherapy; D028321:Plant Preparations / Q000494:pharmacology / Q000627:therapeutic use*; D044945:Proanthocyanidins / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds; D030262:Soybean Proteins / Q000494:pharmacology / Q000627:therapeutic use; D013025:Glycine max / Q000737:chemistry*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D007529:Isoflavones; D028321:Plant Preparations; D044945:Proanthocyanidins; D012333:RNA, Messenger; D030262:Soybean Proteins; D053143:Caspase 2; D053181:Caspase 8; D009955:Ornithine Decarboxylase