Background: Rice bran proteins and their hydrolysates exhibit anticancer activity. Our previous study demonstrated that Riceberry glutelin and its hydrolysates possessed potent in vitro antioxidant and antimutagenic properties. However, their cancer chemopreventive effects in animals remain unclear.Methods: This study investigated chemopreventive mechanisms in diethylnitrosamine (DEN)- and 1,2-dimethylhydrazine (DMH)-induced preneoplastic lesions, including glutathioneS-transferase placental form (GST-P)-positive foci in the liver and aberrant crypt foci (ACF) in the colon of rats. Rats received GTL, GTLH, and total protein hydrolysate (TPH) at 500 mg/kg body weight, five days per week for ten weeks.Results: GTLH significantly reduced GST-P-positive foci in the liver and ACF in the colon, while GTL decreased GST-P-positive foci only in the liver. However, TPH did not affect preneoplastic lesions in both the liver and the colon. GTLH suppressed cell proliferation by reducing proliferating cell nuclear antigen (PCNA)-positive cells and promoted apoptosis, as indicated by an increase in terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells in both organs. GTL also decreased PCNA-positive cells in the liver and colon. Moreover, GTLH significantly upregulatedBAXandCASP3in the liver, while onlyBAXin the colon was observed.Conclusions: This study highlighted the cancer chemopreventive potential of Riceberry GTLH with its underlying mechanism to reduce the number of preneoplastic lesions in the liver and colon through cell proliferation inhibition and apoptosis induction. These findings suggested that this protein hydrolysate might be used as a functional food ingredient or dietary supplement for cancer prevention.
背景：米糠蛋白及其水解产物具有抗癌活性。我们先前的研究表明，Riceberry谷蛋白及其水解产物在体外表现出显著的抗氧化和抗诱变特性。然而，其在动物体内的癌症化学预防作用尚不明确。 方法：本研究探讨了Riceberry谷蛋白（GTL）、谷蛋白水解产物（GTLH）和总蛋白水解产物（TPH）对二乙基亚硝胺（DEN）和1,2-二甲基肼（DMH）诱导的大鼠肝脏胎盘型谷胱甘肽S-转移酶（GST-P）阳性灶和结肠异常隐窝灶（ACF）等癌前病变的化学预防机制。大鼠以500毫克/公斤体重的剂量接受GTL、GTLH和TPH干预，每周五天，持续十周。 结果：GTLH显著减少了肝脏中的GST-P阳性灶和结肠中的ACF，而GTL仅减少了肝脏中的GST-P阳性灶。然而，TPH对肝脏和结肠的癌前病变均无影响。GTLH通过减少增殖细胞核抗原（PCNA）阳性细胞来抑制细胞增殖，并通过增加两个器官中末端脱氧核苷酸转移酶dUTP缺口末端标记（TUNEL）阳性细胞来促进细胞凋亡。GTL也减少了肝脏和结肠中的PCNA阳性细胞。此外，GTLH显著上调了肝脏中的BAX和CASP3基因表达，而在结肠中仅观察到BAX基因表达上调。 结论：本研究揭示了Riceberry GTLH的癌症化学预防潜力，其潜在机制是通过抑制细胞增殖和诱导细胞凋亡来减少肝脏和结肠中癌前病变的数量。这些发现表明，该蛋白水解产物可能作为一种功能性食品成分或膳食补充剂用于癌症预防。
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