Новые доказательства фармакологической активности и возможных молекулярных мишеней полисахаридов ягоды Годжи
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Anticancer effectsAccording to GLOBOCAN 2012,29 an estimated 14.1 million new cancer cases and 8.2 million cancer-related deaths occurred in 2012 worldwide, compared with 12.7 million and 7.6 million, respectively, in 2008. The most commonly diagnosed cancers worldwide were those of the lung (1.8 million, 13.0% of the total), breast (1.7 million, 11.9%), and colorectum (1.4 million, 9.7%).29 The most common causes of cancer death were cancers of the lung (1.6 million, 19.4% of the total), liver (0.8 million, 9.1%), and stomach (0.7 million, 8.8%). Projections based on the GLOBOCAN 2012 estimates predict a substantive increase to 19.3 million new cancer cases per year by 2025, due to growth and aging of the global population.29 Cancer cells contain genetic mutations and have dysregulation of cell cycle, apoptosis, autophagy, and other critical processes. Presently, main cancer therapy modalities include surgery, radiation, hormone therapy, chemotherapy, and immunotherapy. The effect of radiotherapy, chemotherapy, immunotherapy, and hormone therapy is often compromised due to development of drug resistance and severe side effects. In this regard, there is a strong need to identify safe and potent anticancer compounds from natural resources. LBPs have been found to have apoptotic and anti-proliferative effects on cancer cells in vitro and in vivo, and LBPs may enhance the effects and reduce the side effects of other cancer therapies.30 Breast cancerBreast cancer is the most common cancer in women worldwide. In 2012, 1.7 million women were diagnosed with breast cancer and 522,000 women died from breast cancer.29 In 2010, 206,966 women and 2,039 men in the US were diagnosed with breast cancer, and 40,996 women and 439 men died from this disease.31 Current chemotherapy for advanced breast cancer often fails due to tumor resistance and adverse drug effects. Natural medicines have become an important complementary approach for breast cancer treatment. Li et al32 first reported that LBPs inhibited the growth of Michigan Cancer Foundation-7 (MCF-7) cells by changing the metabolic pathways of estradiol. LBPs exhibited a dose-dependent growth inhibition of MCF-7 cells by 9.5%–42.8% at day 3 and by 33.9%–83.9% at day 7. The 3-day inhibitory response to 1% LBPs (maximum cytostatic concentration) exhibited 84.8% increase in estrone (E1), 3.6-fold increase in 2-OH-E1, 33.3% decrease in 16α-OH-E1, and 9.2-fold increase in estriol (E3) formation.32 Notably, LBPs appear to inhibit the proliferation of estrogen receptor-positive MCF-7 cells via modulation of estrogen metabolism and switch of metabolic pathways. Shen and Du33 investigated the mechanisms for the anti-proliferative effects of LBPs on MCF-7 cells. These cells were treated with 10–300 mg/L LBPs for 24 hours. LBP treatment arrested MCF-7 cell cycle in S phase.33 LBPs dose-dependently activated extracellular signal-regulated kinase 1/2 (Erk1/2), which was associated with the expression of p53. These results indicated that LBPs inhibit the growth of MCF-7 cells through activation of Erk1/2. Telang et al34 compared the efficacy of aqueous extracts from L. barbarum bark (LBB) and LBF on MCF-7 cells. LBB exhibited greater potency than LBF (95% reduction in the half maximal inhibitory concentration). LBB produced a 6.8-fold increase, 40% decrease, and a 3.7-fold increase in 2-OH-E1, 16α-OH-E1, and E3 formation. The corresponding values for LBF were 3.9, 33, and 10.5. LBB produced a 16.3-fold and twofold increase in 2-OH-E1:16α-OH-E1 and E3:16α-OH-E1 ratios, whereas LBF produced a six- and 2.9-fold increase, respectively. The efficacy of LBB is due to increased 2-OH-E1 formation, whereas that of LBF is due to accelerated conversion of 16α-OH-E1 to E3. Specific growth inhibitory profiles of LBB and LBF may be due to their distinct chemical composition and their complementary actions on estrogen metabolism. Cervical carcinomaCervical carcinoma is the third most common cancer in women, accounting for 9% of all female cancers and 9% of all cancer deaths in women.29 It is the seventh most common cancer in the world, with an estimated 528,000 new cases in 2012. Cervical carcinoma is the fourth most common cancer in women worldwide, after breast, colorectal, and lung cancers. There were an estimated 266,000 deaths from cervical cancer worldwide in 2012, accounting for 7.5% of all female cancer deaths.29 In 2010, 11,818 women in the US were diagnosed with cervical cancer and 3,939 women died from this disease. Cervical cancer is the sixth most common cancer in Europe for women, with around 58,400 new cases diagnosed in 2012. In 2011, there were 3,064 new cases of cervical cancer and 972 deaths from cervical cancer in the UK. Cervical cancer is predominantly a disease of low-income countries, with overall rates nearly twice as high in less developed regions compared to more developed regions. Cervical cancer incidence rates are highest in Eastern Africa and lowest in Western Asia. There is increased interest in seeking new therapies for cervical carcinoma from natural compounds. Hu et al35 used LBPs in combination with garlic to treat mice bearing human cervical U14 cancer. Examination of ascitic fluid revealed damage of the cancer cells by LBPs plus garlic, blanching of fluorescence staining of DNA and RNA, and the cancer cells besieged by large numbers of macrophages and leukocytes.35 Flow cytometric analysis found accumulation of cells in G1 phase. The number of S phase cells decreased from 56% to 49%, and the number of G0/G1 phase cells increased from 16% to 33%. LBPs plus garlic also resulted in swelling of mitochondria in cytoplasm, damage of mitochondrial crests with cavity formation, and enlargement and degranulation of rough endoplasmic reticulum.35 Zhu and Zhang36 investigated the mechanisms for the anti-proliferative effects of LBPs in human cervical cancer HeLa cells. LBPs were extracted from dried fruits of L. barbarum harvested in Ningxia, People’s Republic of China. Incubation of HeLa cells with 6.25 mg/mL LBPs for 4 days resulted in a 35% inhibition of cell growth. A significant accumulation of cells in the S phase (46.9%–59.4%) and sub-G1 phase (3.1%–5.0%, indicating cellular apoptosis) was observed when treated with 6.25–100 mg/L LBPs for 4 days, together with significantly decreased proportions of cells in the G0/G1 phase (from 56.8% to 31.4%).36 The loss of mitochondrial transmembrane potential (Δψm) was observed by flow cytometer; and the percentage of Δψm collapse was 6.78% following treatment with 6.25 mg/L LBPs. LBPs also dose-dependently increased intracellular Ca2+ concentration as detected by laser scanning confocal microscope in apoptotic cells. About 6.25–100 mg/L LBPs increased the NO content in the medium from 33.67 µM at the basal level to 79.17–101.03 µM in HeLa cells.36 The NO synthase and inducible NO synthase activities in the culture medium were also significantly increased in HeLa cells treated with 100 mg/L LBPs. These findings indicate that LBPs inhibit the growth of HeLa cells through induction of mitochondria-mediated apoptosis.
Colorectal cancerColorectal cancer is the third most common cancer in the world, with nearly 1.4 million new cases diagnosed in 2012.29 Colorectal cancer is the second leading cause of cancer-related deaths in the US and the third most common cancer in men and women.37 In 2010, 131,607 people in the US were diagnosed with colorectal cancer, including 67,700 men and 63,907 women; 52,045 people died from this disease, including 27,073 men and 24,972 women.37 In 2011, 41,581 people in the UK were diagnosed with colorectal cancer and 15,659 people died from this disease. As a result of the relatively poor prognosis and response to conventional chemo- and radiotherapy, there is a great need for the discovery of new effective agents for colorectal cancer. When human colon cancer cell lines SW480 and Caco-2 cells were treated with 100–1,000 mg/L LBPs for 1–8 days, LBPs inhibited the proliferation of both cell lines in a dose-dependent manner.38 At concentrations from 400 mg/L to 1,000 mg/L, LBPs significantly inhibited the growth of SW480 cells; while at concentrations from 200 mg/L to 1,000 mg/L, they significantly inhibited the growth of Caco-2 cells.38 The crystal violet assay showed that the number of adherent cancer cells was decreased by treatment with 100–1,000 mg/L LBPs for 8 days. Cells were arrested at the G0/G1 phase with a decrease in S phase when treated with LBPs.38 About 100–1,000 mg/L LBPs downregulated the expression of cyclin D, cyclin E, and cyclin-dependent kinase 2 (CDK2) in colon cancer cells. Cyclin E/CDK2 regulates multiple cellular processes by phosphorylating numerous downstream proteins. There is deregulated expression of cyclin D, cyclin E, and CDK2 in colorectal cancer. These data demonstrate the antiproliferative effects of LBPs against colorectal cancer cells via modulation of critical cell cycle regulators. Gastric cancerGastric cancer is the fifth most common cancer and the third leading cause of death from cancer globally with approximately 952,000 new cases and 723,000 deaths making up 7% of all cancer cases and 9% of deaths.29,39 Almost two-thirds of gastric cancer cases occur in developing countries and 42% in People’s Republic of China accounting for 3.99% of all deaths.40 There are about 22,220 new cases of gastric cancer and 10,990 deaths every year in the US. In the UK, 7,089 people were diagnosed with gastric cancer and 4,830 deaths due to this disease were recorded in 2011.40 The 5-year relative survival rate of gastric cancer is as low as <10%.39–42 Therefore, there is an urgent need to identify novel therapeutic strategies for later stage gastric cancer. When human gastric cancer MGC-803 and SGC-7901 cells were treated at various concentrations of LBPs for 1–5 days, LBP treatment inhibited the growth of MGC-803 and SGC-7901 cells, with cell cycle arrest at the G0/G1 and S phases, respectively.43 The changes in cell cycle-associated proteins, such as cyclins and CDKs, were consistent with the changes in cell cycle distribution. The results suggested that induction of cell cycle arrest contributes to the anticancer activity of LBPs in gastric cancer cells. LeukemiaLeukemia is a cancer of the white blood cells and bone marrow. Worldwide, around 352,000 people were estimated to have been diagnosed with leukemia in 2012.29 In 2014, it is estimated that there will be 52,380 new cases of leukemia and an estimated 24,090 people will die of this disease in the US.40 In 2011, 8,616 people in the UK were diagnosed with leukemia (all subtypes combined) and there were 4,603 deaths from leukemia. In Europe, around 82,300 new cases of leukemia were estimated to have been diagnosed in 2012. There are four main subtypes of leukemia: acute myeloid leukemia, acute lymphoblastic leukemia, chronic myeloid leukemia, and chronic lymphocytic leukemia. About 20–1,000 mg/L LBPs inhibited the growth of human promyelocytic leukemia HL-60 cells in a dose-dependent manner.44 LBPs also induced the apoptosis of HL-60 cells as determined by DNA ladder and terminal deoxynucleotidyl transferase dUTP nick end labeling assays. Liver cancerLiver cancer is the sixth most common cancer in the world, with 782,000 new cases diagnosed in 2012.29 Worldwide, it is the third leading cause of cancer deaths. The estimated number of new cases with liver cancer in 2014 in the US is 33,190, with estimated deaths of 23,000 due to liver cancer.40 In the UK, 4,348 people were diagnosed with liver cancer in 2011 and 4,106 people died from liver cancer in 2011. Hepatocellular carcinoma is the most common type of primary liver cancer, and factors that increase the risk of developing hepatocellular carcinoma include long-term, heavy alcohol use and chronic infection with hepatitis B or C viruses. Zhang et al45 reported that 100 mg/L LBPs inhibited the proliferation of human hepatoma QGY7703 cells, induced cell cycle arrest, and significantly increased intracellular Ca2+ level. When rat H-4-II-E and human liver cancer HA22T/VGH cell lines were incubated with various concentrations of crudeL. barbarum extract (mainly LBPs), the extract at ≥5 g/L inhibited the cellular proliferation, promoted G2/M phase arrest, and stimulated p53-mediated apoptosis in H-4-II-E and HA22T/VGH cells.46 The effect may be due to inhibition of nuclear factor (NF)-κB that alters the expression of regulatory cell cycle proteins such as cyclin B and p21WAF1/Cip1. Zhang et al47 found that different fractions of LBPs at the dose of 50–400 mg/L for 2 days, 4 days, and 6 days showed distinct effects on the proliferation, cell cycle distribution, and apoptosis in human liver cancer SMMC-7721 cells. LBP-a4 had the highest inhibition activity of 36.5%±2.6% at the dose of 400 mg/L for 2 days. LBPs were extracted from fruits of Chinese wolfberry obtained from Xinjiang province, People’s Republic of China, and LBP fractions were isolated by ultrafiltration membranes with molecular weight cutoff (MWCO) of 80 kDa, 30 kDa, 10 kDa, and 4 kDa successively. Polysaccharides fractions LBP-a8, LBP-p8, LBP-a3, LBP-a1, and LBP-a4 were obtained by freeze-drying the retentates of ultrafiltration with MWCO of 80 kDa, 30 kDa, and 10 kDa and permeates of ultrafiltration with MWCO of 4 kDa. The results showed that LBP-a8, LBP-a3, LBP-a1, and LBP-a4 inhibited the growth of SMMC-7721 cells in a concentration- and time-dependent manner.47 In contrast, LBP-p8 promoted the proliferation of SMMC-7721 cells to 183.5%±4.7% of the control group at the concentration of 200 mg/L for 4 days. Treatment of SMMC-7721 cells with 400 mg/L LBP-a4 for 4 days arrested the cells at G0/G1 phase and increased the intracellular Ca2+ concentration.47 Cells treated with LBP-a4 at G0/G1 phase increased from 49.21% to 69.65%, while cells at S phase and G2/M phase decreased from 40.53% and 10.26% to 24.79% and 5.56%, respectively. However, incubation of cells with 200 mg/L LBP-p8 for 4 days only slightly increased the cell ratio of G0/G1 (52.84%) and S (42.13) phase. The intracellular Ca concentration of SMMC-7721 cells treated with 400 mg/L LBP-a4 for 4 days was 1.59-fold higher than that of control cells, while that of LBP-p8-treated cells was only 1.07 times higher than that of control cells.47 LBP-a4 consisted of 11.5% uronic acid, 0.34% protein, and 39.02% neutral sugar, while LBP-p8 consisted of 13.4% uronic acid, 4.77% protein, and 26.26% neutral sugar. LBP-p8 consisted of seven kinds of monosaccharides including fucose, rhamnose, arabinose, xylose, glucose, mannose, and galactose, and LBP-a4 was composed of six kinds of monosaccharides including fucose, arabinose, xylose, glucose, mannose, and galactose (Figure 1C). The average molecular weight of LBP-a4 and LBP-p8 were 10.20 kDa and 6.50×103 kDa, respectively. These findings demonstrate a clear impact of LBP components and structures on the activities of LBPs. SarcomaSarcoma is a type of cancer that develops from certain tissues such as bone or muscle.48 There are two main types of sarcoma: bone sarcomas and soft tissue sarcomas. Soft tissue sarcomas can develop from soft tissues like fat, muscle, nerves, fibrous tissues, blood vessels, or deep skin tissues. The most common types of sarcoma in adults are malignant fibrous histiocytoma, liposarcoma, and leiomyosarcoma. About 12,020 people (6,550 males and 5,470 females) will be diagnosed with soft-tissue sarcoma in the US and an estimated 4,740 people will die of the disease in 2014.40 Around 3,300 people were diagnosed with soft tissue sarcoma in 2010 in the UK. For sarcomas that have spread to distant parts of the body, the five-year survival is 16%. The effect of a polysaccharide–protein complex from L. barbarum (LBP3p) on the immune system in S180-bearing mice was investigated by Gan et al.49 The mice inoculated with S180 cell suspension were treated orally with 5 mg/kg, 10 mg/kg, and 20 mg/kg LBP3p for 10 days. The effects of LBP3p on transplantable tumors and macrophage phagocytosis, quantitative hemolysis of mouse red blood cells, lymphocyte proliferation, cytotoxic T lymphocyte (CTL) activity, IL-2 gene expression, and lipid peroxidation were determined. LBP3p significantly inhibited the growth of transplantable sarcoma S180 and increased macrophage phagocytosis, the form of antibody secreted by spleen cells, spleen lymphocyte proliferation, CTL activity, IL-2 messenger (m) RNA expression level and reduced the lipid peroxidation in S180-bearing mice.49 The dose of 10 mg/kg LBP3p was more effective than that of 5 mg/kg and 20 mg/kg LBP3p. These data suggest that LBP3p inhibited sarcoma growth in vivo via enhanced immune activities. Prostate cancerProstate cancer is the second most common cancer in men worldwide, after lung cancer.50 There were over 903,500 new prostate cancer cases reported worldwide and an estimated 258,400 men died from this disease in 2008.29 In the US, 196,038 men were diagnosed with prostate cancer, and 28,560 men died from this disease in 2010.51 In the UK, 40,975 men were diagnosed with prostate cancer in 2010, and 10,793 men died from this disease in 2011.52 Chemotherapy for prostate cancer usually brings drug resistance and severe adverse reactions in patients. Therefore, new anticancer drugs that can prevent the progression of prostate cancer and execute prostate cancer cells with improved efficacy and reduced side effects are urgently needed. The effects of LBPs on the growth of human prostate cancer cells were examined in vitro and in vivo by Luo et al.53 LBPs inhibited the growth of both PC-3 and DU-145 cells in a dose- and time-dependent manner, by breaking their DNA strands and inducing the apoptosis of these cells. The Bcl-2/Bax expression decreased significantly after LBP treatments and the ratio of Bcl-2/Bax expression following LBP treatment also decreased significantly with a dose–effect relationship,53 which suggested that LBPs regulated the expression of Bcl-2 and Bax to induce apoptosis of PC-3 and DU-145 cells. The animal study showed that LBPs significantly inhibited PC-3 xenograft growth in nude mice with significant reduction of the tumor volume and weight in the LBP-treated group than in those of the control group.53 Clinical study of LBPs in cancer patientsIn a clinical trial, 79 patients with advanced cancer were treated with lymphokine-activated killer (LAK)/IL-2 in combination with LBPs.54 Initial results indicated that objective regression of cancer was achieved in patients with malignant melanoma, renal cell carcinoma, colorectal carcinoma, lung cancer, nasopharyngeal carcinoma, and malignant hydrothorax. The response rate of patients treated with LAK/IL-2 plus LBPs was higher than that of patients treated with LAK/IL-2 alone.54 The mean remission in patients treated with LAK/IL-2 plus LBPs also lasted significantly longer. LAK/IL-2 plus LBP treatment led to more marked increase in natural killer (NK) and LAK cell activity than LAK/IL-2 alone.54 LBPs may be used as an adjuvant in the biotherapy of cancer. Summary of the anticancer activities of LBPsLBPs inhibit the proliferation of various types of cancer cells and induce cell cycle arrest at the G0/G1, S, or G2/M phase (Figure 4). They inhibit the growth of cancer xenografts in nude mice. In cancer patients, LAK/IL-2 plus LBP treatment leads to more marked increase in NK and LAK cell activity than LAK/IL-2 alone (Figure 5). LBPs regulate the expressions of Bcl-2 and Bax to induce tumor cell apoptosis by increasing intracellular Ca2+ concentration and mitochondrial pathway. Furthermore, LBPs inhibit the growth of MCF-7 cells through activation of Erk1/2 and modulation of estrogen metabolism. LBPs downregulate the expression of cyclin D, cyclin E, and CDK2 in colon cancer cells. Moreover, LBPs stimulate p53-mediated apoptosis in liver cancer cells due to inhibition of NF-κB. Figure 4 
Possible mechanisms for the anticancer activities of LBPs. Notes: LBPs inhibit the proliferation of various types of cancer cells and induce cell cycle arrest at the G0/G1, S, or G2/M phase. LBPs inhibit the growth of cancer xenografts in nude mice. In cancer patients, LAK/IL-2 plus LBP treatment leads to more marked increase in NK and LAK cell activity than LAK/IL-2 alone. LBPs regulate the expression of Bcl-2 and Bax to induce tumor cell apoptosis via increasing intracellular Ca2+ concentration and mitochondrial pathway. LBPs inhibit the growth of MCF-7 cells through activation of Erk1/2 and modulation of estrogen metabolism. LBPs downregulate the expression of cyclin D, cyclin E, and CDK2 in colon cancer cells. LBPs stimulate p53-mediated apoptosis in liver cancer cells due to inhibition of NF-κB. Abbreviations: LBPs, Lycium barbarum polysaccharides; IL-2, interleukin-2; NK, natural killer; LAK, lymphokine activated killer; MCF-7, Michigan Cancer Foundation-7; CDK2, cyclin-dependent kinase 2; NF-κB, nuclear factor κB. Figure 5 
LBPs potentiate the immune-enhancing activity of LAK/IL-2 therapy in cancer patients. Notes: LBPs enhance NK and LAK cell activities in cancer patients treated with LAK/IL-2, resulting in an increase in tumor cell lysis and death. Abbreviations: LBPs, Lycium barbarum polysaccharides; IFN, interferon; IL-2, interleukin-2; NK, natural killer; LAK, lymphokine activated killer; TNF, tumor necrosis factor. |