| 摘要: | 傳統的草藥，金線連（Anoectochilus formosanus Hayata）已被用於治療各種疾病。高血糖誘導活性氧物質（ROS）的產生並增強氧化壓力，這些都是癌症進展和轉移的風險因素。在本研究中，評估了A. formosanus萃取物（AFE）在果糖誘導高血糖動物模式中的降血糖作用，並建立與高血糖症及癌變進程因子的關聯性。結果顯示AFE沒有影響正常動物的血糖，對實驗組糖尿病小鼠具有抗高血糖作用。在AFE處理的高血糖小鼠中，血糖反應曲線下的增量面積（AUC）顯著降低，呈劑量依賴性。在50 mg/kg的相同給藥劑量下，AFE和二甲雙胍(Metformin)對高血糖小鼠的腹膜內葡萄糖耐受性試驗，顯示相似的降血糖作用。
糖尿病病程中，代謝異常、肥胖、高血糖和高胰島素血症等都與癌症發生和進展有關。本研究也評估了AFE與癌症細胞的作用，也在胰島素刺激的癌細胞與脂肪細胞下，探討AFE產生的影響。口腔癌SCC-25細胞中經AFE處理之後，癌細胞PD-L1的表現受到抑制，且其蛋白質累積也減少。它抑制PD-L1的表現外,減少發炎基因COX-2和TNF-α，並抑制增殖和轉移基因CCND1和c-Myc和轉移基因MMP-2基因的表現。此外，AFE抑制促凋亡CASP2及誘導抗凋亡BAD基因的表現，及具有抑制口腔癌SCC-25細胞的增殖作用。
二甲雙胍(Metformin)常被報導與降低各種類型癌症的發生風險，與它的抗發炎和維持免疫多功性相關。AFE 除了具有二甲雙胍(Metformin)相似降血糖作用外，在抑制PD-L1表現、COX-2和TNF-α的表現，且調降CCND1和c-Myc和轉移基因MMP-2基因的表現，及細胞凋亡CASP2及抗凋亡BAD基因的表現皆優於二甲雙胍(Metformin)。說明AFE改善高血糖外，在預防癌症進程的作用上是藉由過抑制高血糖與免疫檢查點相關PD-L1表現，並同時降低了炎症和增殖基因的表現。
以胰島素誘導的結直腸癌HCT116細胞和3T3-L1脂肪細胞基因表現的影響，探討AFE及乙酸乙酯分劃及黃酮類成分檞皮素(Quercetin)的影響，胰島素增加HCT116細胞中PD-L1和TNF-α的表現，AFE、EA分劃(Ethyl acetate fraction of AFE) 都抑制TNF-α、Glu4和HK1的表現。胰島素活化TNF-α表現顯著的增加，可被AFE，EA分劃和槲皮素抑制。另外 受胰島素刺激加強後，AFE、EA分劃和槲皮素抑制胰島素的活性作用。在3T3-L1細胞中，AFE、EA分劃、槲皮素和胰島素均可抑制TNF-α、Glut1和HIF1α的表現，但僅AFE可反轉胰島素誘導的TNF-α，Glut1，HIF1α表達的抑制作用。
綜合本研究的證據，在果糖誘發肥胖及糖尿病小鼠模式下，AFE的清除自由基可以減少ROS，及降低血糖效果可與同劑量的二甲雙胍(Metformin)相似。藉著自由基清除能力及抑制PD-L1基因表現，AFE透過抑制PD-L1蛋白表現參與抗癌細胞增殖的機制，抑制發炎反應、增殖和轉移基因的表現。建議AFE可發展應用在輔助癌症預防或癌症治療對抗藥物誘導的高血糖症，以增強抗癌療效，特別是在表現PD-L1且處於高血糖症併發的腫瘤疾患。
Traditional herb medicine, golden thread (Anoectochilus formosanus Hayata) has been used to treat various diseases. Hyperglycemia induces generation of reactive oxygen species enhancement of oxidative stress which are risk factors for cancer progression and metastasis. In this study, we evaluated hypoglycemic effect of A. formosanus extracts (AFE) in an inducible hyperglycemia animal model and its capacity of free-radical scavenging to establish hyperglycemia-related carcinogenesis. AFE reduced blood glucose in hyperglycemic mice while there was no change in control group. The incremental area under blood glucose response curve was decreased significantly in hyperglycemic mice treated with AFE in a dose-dependent manner. AFE and metformin at the same administrated dose of 50 mg/kg showed similar effect on intraperitoneal glucose tolerance test in hyperglycemic mice.
Metabolic syndrome, obesity, hyperglycemia, and hyperinsulinemia are all associated with cancer development and progression during the course of diabetes. This study also evaluated the effects of AFE on cancer cells and explored the effects of AFE in insulin-stimulated cancer cells and adipocytes. Treatment of SCC25 oral cancer cells with AFE inhibited constitutive PD-L1 expression and its protein accumulation. In addition, it also reduces the inflammatory genes COX-2 and TNF-α, and inhibits the expression of the proliferation and transfer genes CCND1 and c-Myc and the transfer gene MMP-2 gene. AFE also inhibits the expression of pro-apoptotic CASP2 and induces anti-apoptotic BAD genes, and has an anti-cancer proliferative effect, which can inhibit the proliferation of oral cancer SCC-25 cells.
Metformin is reported to reduce the risk of various types of cancer, pancreatic, colorectal and hepatocellular carcinoma etc. is associated with its anti-inflammatory and maintenance of immune pluripotency. In addition to the similar hypoglycemic effect of metformin, AFE inhibits PD-L1, COX-2 and TNF-α expression, and down-regulates the expression of CCND1 and c-Myc and MMP-2 gene, and apoptosis CASP2 and enhancing the anti-apoptotic BAD gene is superior to metformin. The results suggested that AFE not only reduced blood glucose concentration as metformin but also showed its potential use in cancer immune chemoprevention/therapy via hypoglycemic effect, ROS scavenging and PD-L1 suppression.
Effect of AFE on insulin-induced gene expression in colorectal cancer HCT116 cells and 3T3-L1 adipocyte cells were further investigated. In order to examine the effect of AFE on insulin-induced gene expression, colorectal cancer HCT116 cells and 3T3-L1 cells were treated with insulin and in the presence or absence of AFE, EA fraction of AFE and quercetin. It is shown that insulin increased the expression of PD-L1 and TNF-α in HCT116 cells. AFE and EA fraction can inhibite the expression of TNF-α, Glu4 and HK1. Insulin activated TNF-α showed a significant increase and was inhibited by AFE, EA and quercetin. In addition, AFE, EA fraction and quercetin inhibit the stimulation of insulin on genes expression as treated with insulin. In adipocyte 3T3-L1 cells, AFE, EA fraction, quercetin and insulin all inhibited the expression of TNF-α, Glut1 and HIF1α, but only AFE could further reverse the inhibition of insulin-induced expression of TNF-α, Glut1 and HIF1α.
Based on the evidence in this study, in the model of fructose-induced obesity and diabetes mice, AFE scavenging free radicals can reduce ROS, and lower blood sugar can be similar to those of metformin at same dose. By inhibiting the ability of free radical scavenging and inhibiting the expression of PD-L1 gene, AFE inhibits the expression of anti-inflammatory cells by inhibiting expression of PD-L1 protein and inhibiting the proliferation of cancer cells. It is suggested that AFE can be used in helping cancer prevention or cancer treatment to combat drug-induced hyperglycemia and enhance anticancer efficacy, especially in tumors that exhibit PD-L1 and are associated with hyperglycemia. |
