Eliza Lamer-Zarawska
1, Agnieszka Wiśniewska
2, Zofia Błach-Olszewska
2Anticancer Properties of
Scutellaria baicalensis
Root
in Aspect of Innate Immunity Regulation
Przeciwnowotworowa aktywność tarczycy bajkalskiej
w świetle regulacji wrodzonej odporności
1 Department of Biology and Pharmaceutical Botany, Wroclaw Medical University, Poland 2 Ludwik Hirszfeld Institute of Immunology and Experimental Therapy,
Polish Academy of Sciences, Wrocław, Poland
Abstract
Cancer disease is accompanied by inflammation, oxidative stress, strong proliferation of cancer cells with growth of tumor and its vascularisation, metastases and also by reduction of innate immunity. Anticancer effect of Scutellaria baicalensis flavones in view of present literature data is discussed. Inhibition of growth different tumor cell lines by flavones isolated from root of the plant: wogonin, baicalein and baicalin, but not wogonoside is presented. The anticancer activity of the flavones is connected with reduction of high level reactive oxygen species (ROS), reduc-tion of inflammatory reacreduc-tion, and NFκB activareduc-tion. Inhibireduc-tion of cell cycle and involvement cyclins in the process is discussed. The most important anticancer reaction of Scutellaria flavones is stimulation of apoptosis of cancer cells. Molecular mechanism of anti-prostate, anti-breast cancer activity of Scutellaria baicalensis extract and herbal mixture PC-SPES is discussed. Role of flavonoids obtained from Scutellaria extracts in human leukemia cell lines are described. Importance of leukocyte antiviral innate immunity for chemotherapy and course of acute leukemia disease is presented. Strengthening of the leukocyte antiviral resistance by flavones of Scutellaria baicalensis and modulation of cytokines production seem also very important in cancer therapy (Adv Clin Exp Med 2010, 19, 4, 419–428).
Key words: anticancer properties, Scutellaria baicalensis flavones, reduction of inflammation, inhibition of cell cycle, stimulation of apoptosis, effect on innate immunity.
Streszczenie
Chorobie nowotworowej zwykle towarzyszą procesy zapalne, stres oksydacyjny, silna proliferacja komórek nowotworowych prowadząca do wzrostu guza i jego waskularyzacja, przerzutowanie oraz obniżenie wrodzonej odporności. Na podstawie danych z piśmiennictwa omówiono przeciwnowotworowe działanie flawonów z tarczycy bajkalskiej (Scutellaria baicalensis Georgi). Flawony izolowane z korzenia tarczycy bajkalskiej, takie jak: wogonina, bajkaleina i bajkalina, hamują wzrost komórek linii nowotworowych, podczas gdy wogonozyd nie wykazuje takiej aktywności. Przeciwnowotworowa aktywność flawonów jest związana z ograniczeniem reaktywnych form tlenu (ROS), zmniejszeniem procesów zapalnych i hamowaniem aktywacji jądrowego czynnika transkrypcyjnego NFκB. Hamowanie cyklu komórkowego przez flawony i udział cyklin w tym procesie, a także wpływ na apopotyczne pro-cesy analizowano pod kątem przeciwnowotworowej aktywności flawonów. Bardziej szczegółowo przedstawiono molekularne mechanizmy towarzyszące rezultatom działania ekstraktów z tarczycy bajkalskiej i mieszanki ziołowej PC-SPES w nowotworach prostaty (PC-SPES) i raku piersi (ekstrakt). Hamowanie proliferacji komórek linii białaczkowych przez flawony z korzenia tarczycy wskazuje na ich potencjalną rolę w leczeniu białaczki. Podkreślono także znaczenie wrodzonej odporności dla leczenia i przebiegu ostrej białaczki oraz o możliwym jej wzmacnianiu przez flawony uzyskane z korzenia tarczycy bajkalskiej (Adv Clin Exp Med 2010, 19, 4, 419–428).
Słowa kluczowe: aktywność przeciwnowotworowa, flawony tarczycy bajkalskiej, aktywność przeciwzapalna, hamowanie cyklu komórkowego, stymulacja apoptozy, wpływ na wrodzoną odporność.
Adv Clin Exp Med 2010, 19, 4, 419–428 ISSN 1230-025X
EDITORIAL
Two main problems of present chemotherapy that play a major role in treatment of tumor pa-tients include: toxicity of drugs toward normal tissue and development of resistance of the tumor cells toward apoptosis. Thus, it is an urgent re-quirement to improve cancer therapy. Minimizing side-effects and maximizing efficacy became a ma-jor goal in the development of apoptosis inducers. Traditional Chinese remedies have been re-cently recognized as a new source of anticancer drugs (inducers of apoptosis) and new chemo-therapy adjuvant to enhance the efficacy of the therapy and to ameliorate its side effects. However, their healing mechanisms are still not completely known.
Scutellaria baicalensis Radix (common name: Huang-Qin in China, and Ougon in Japan), and its flavonoid compounds as: baicalin, baicalein, wogonin, oroxylin and others, is one of the most popular, and multi-purpose remedy used in China, Japan and in several oriental countries. In Tradi-tional Chinese Medicine (TCM) extracts from the roots obtained from various species of genus Scutel-laria, especially Scutellaria baicalensis Georgi, are widely used for clinical treatment of hyperlipidae-mia, atherosclerosis, hypertension, dysentery, com-mon cold, viral, bacterial and inflammatory disease (esp. atopic dermatitis)and others [1].
Apart from above properties, Scutellaria alone, or in combination with other herbs, has been re-cently shown to possess cytostatic effect on several cancer cell lines in vitro [1–3] and also in vivo in mouse tumor models [4, 5]. The low toxicity to non-malignant cells has made Scutellaria baicalen-sis very attractive as a new anticancer drug.
The Bioactive Constituents
of
Scutellaria Baicalensis
Radix
The major constituents of Scutellaria ba-icalensis radix (Scutellaria baba-icalensis Georgi) are flavonoids, chiefly baicalin (up to 14%), baicalein (up to 5%), wogonin (0.7%) and wogonin-7-0-glucoronide (wogonoside, 4.0%). To identify the antitumor components of Scutellaria sp., many studies have been carried out using purified com-pounds. Antitumor constituents of these spe-cies, especially Scutellaria baicalensis Georgi, are flavones: baicalin (baicalein 7-O-glucuronide), baicalein (5,6,7-trihydroxyflavone), wogonoside (wogonin 7-O-glucuronide), and wogonin (5,7-dihydroxy-8-methoxyflavone) with ratios to the dry material about 10.11%, 5.41%, 1.3% and 3.55% respectively.
Among the flavones wogonin, baicalein and baicalin have been shown to inhibit growth of various human cancer cell lines. The doses of 50% inhibition of tumor proliferation are ranging be-tween 20 and 200 μM, depending on the types of tumor cells tested. In addition, these compounds also possess a direct cytotoxicity to a large panel of human malignant cell lines by inducing apoptotic cell death.
Molecular Mechanisms
of Antitumor Activity
of
Scutellaria Baicalensis
Radix
Flavonoids
Molecular mechanisms anticancer activity of flavonoids are diverse andinclude: anti- and pro-oxidative effects, cell cycle inhibition, apoptosis induction, inhibition of intracellular signaling by transcription factors (i.e. NFκB), anti-inflammato-ry and also anti-viral activities.
Effect of Flavonoids on ROS
Scavenging
the B-ring and the 5-hydroxy group in the A-ring. The main flavones of Scutellaria baicalensis as baic-alin, baicalein and wogonin possess the 2,3-unsatu-ration and the 4-oxo in the C-ring and the rather rare hydroxylation in plant flavonoids (at C5, C6, C7) in the A-ring, and they provide a high antioxi-dant and anti-radicals properties [7].
The free-radical scavenging activities of baica-lein and baicalin were investigated by Shieh at al. [7]. Both flavonoids exhibited capacity to eliminate the superoxide radical, respectively: bajkalein: 7.31 × 10(4) μ/g; bajkalin: 1.19 × 10(5) μ/g. However they did not have significant effect on scavenging hydroxyl radical. It was supposed that antioxidant activity of baicalin is based on the superoxide radi-cal elimination and bairadi-calein is a pleasing xanthine oxidase inhibitor.
Among the examined flavonoids, wogonin at the highest pitch affects inhibition of nitric oxide production, while oroxylin A inhibits lipid peroxy-dation in the most potent way [6].
Pro-oxidative Activity
of Flavonoids
Several studies showed that flavonoids have not only antioxidative, but also prooxidative ac-tivity [6–8]. It was demonstarated that peroxidase catalyzes one-electron oxidation of the phenolic ring of etoposide (an anticancer compound) and/ or interaction of this phenolic moiety with reac-tive radicals to yield its phenoxy radical. Thereby, etoposide acted as an effective radical scavenger. The peroxidase-catalyzed phenoxyl radicals, al-though did not lead to oxidation of phoospholip-ids (suggesting that the radicals were not reactive enough to trigger lipid oxidation), were shown to contribute pro-oxidant effects via oxidization of glutathione (GSH) and protein tiols in the redox-cycling. The evidence for the pro-oxidant activity of flavonoid phenoxy radicals was shown by their ability to deplete glutathione (GSH) of tumor cells. Wogonin, baicalein and baicalin were all shown to cause depletion of GSH content in human he-patoma cell lines and leukemia cell line therefore it is believed that the anticancer activity of these compounds may also involve a pro-oxidant mech-anism.
Inhibition of NF-κB Activation
by Flavones
NF-κB is an inducible transcription factor that controls the expression of over one hundred genes involved in immunity, inflammation, proliferation,
defense against apoptosis and also ROS. By activa-tion certain intracellular signaling cascades includ-ing NFκB, may contribute to tumor development. NF-κB is often found to be constitutively or over-activated in malignant cells. Currently, activation NF-κB is considered to be involved in a survival and activation expression of various anti-apoptotic genes e.g. BcI-2, BcI-XL, McI-1 that promote
sur-vival of many types of tumors. Tumor cells are also often shown to produce increased levels of ROS due largely to the increased metabolic activity and to mitochondrial malfunction.
Reduced NF-κB activity was observed in my-eloma cell lines after baicalein treatment. Recent studies have shown that wogonin can scavenge.02_
and shifts the cellular redox potential to a more re-duced state H2O2 and thereby down-regulate
ROS-mediated NF-κB activation [10]. In most tumor cell lines wogonin, and baicalein suppressed the expression of genes BcI-2, BcI-X1 and McI-1 [6].
Cell Cycle Inhibition by Flavones
The cell cycle consists of 4 phases: M, G1, S, G2. M phase (mitosis) is usually followed by cy-tokinesis. During interphase, which involves G1, S, G2 phase, a cell grows and replicates its genetic material (DNA). During G1 phase (the interval be-tween mitosis and S phase) succeed RNA and pep-tides synthesis, in S phase succeed DNA replica-tion and in phase G2 (the interval between S phase and mitosis) supergene repair of damaged DNA and preparation the cell for mitosis.
S. baicalensis through cell cycle regulation manages cancer proliferation what has been proved in many experiments. One can distinguish a few checkpoints in cell cycle according to the type of tumors where flavonoids impact is perceptible. Cyclins are one of the regulatory molecules which determine a cell’s progress through the cell cycle.
Significant decrease in cyclin D1 protein level in wogonin treated breast cancer cell lines was af-firmed. Cyclin D1 expression was also suppressed in baicalein treated prostate cancer cell lines. How-ever only in baicalein-treated lung cancer cell lines a decrease in both cyclin D1 and B1 levels was no-ticed. In flavonoids-treated leukemia cell lines the cell cycle was inhibited at G2/M phase [9].
Scutellaria baicalensis caused significant G0-G1 phase arrest with concurrent decrease in S phase in prostate carcinoma cell line. However, baicalein caused a significant G2-M phase arrest and decrease in G0-G1 phase simultaneously [10].
cells, lymphocytic leukemia cells, lymphoma cell lines myeloma cell lines treated with S. baicalen-sis also decreased in S phase and had an increased number of cells in the sub-G1 population.
Apoptosis Induction
It is well-established that anticancer agents induce apoptosis (programmed cell death), which is necessary to keep cellular homeostasis and nor-mal development. Apoptosis induction is one of the major desired effects of anticancer therapy. Proapoptotic baicalin mechanism probably is related with mitochondrial pathway activation. Mechanism of baicalin-induced cytotoxicity in leukemia Jurkat cells was examined. Cells showed characteristic morphologic change of apoptosis. Ueda et al. [12] have shown that baicalin induced cytochrom C release into cytosol, disruption of mitochondrial transmembrane potential, then caspase-3 activation and consequently nuclear degradation. The results indicate that apoptosis by baicalin is mediated by mitochodrial pathway. Baicalein also inducted apoptosis, which was con-firmed by DNA condensation and fragmentation. In cells H 460-treated baicalein affirmed decreas-ing in Bcl-2, increasdecreas-ing in caspase-3 activity and p53 and Bax protein levels. It has been known that p53, which is a tumor suppressor protein, regulate the Bcl-2 and Bax protein expression.
Anti-Inflammatory Effect
in Flavonoids of
Scutellaria
Baicalensis Radix
in Possible
Oncological Therapy
Chronic inflammation may contribute to can-cer development. Flavonoids wogonin, baicalein and baicalin of Scutellaria sp. have been shown to protect tissues from inflammation in vitro and in vivo in various animal models [13–16].
The anti-inflammatory effect of the Scutel-laria flavones is in part due to their inhibition of cytokines production [17] and also nitric oxide (NO) production via down-regulation of several inflammation-associated genes such as inducible NO synthase (iNOS), cyclooxygenases (COX) and lipoxygenases. NO, a highly reactive free radical, and its synthase (NOS) are ubiquitous in malig-nant tumors and are known to exert both pro- and antitumor effects [18–21]. Interaction between NO and p53 is a crucial pathway in inflammatory-me-diated carcinogenesis.
Flavonoids wogonin, baicalein and baicalin were shown to inhibit inducible synthase (iNOS) gene expression and reduce NO production in
vitro and in vivo in animal models [22]. The pro-inflammatory product of elevated cyclooxyge-nase-2 (COX-2) activity, prostaglandin E2 (PGE2), plays direct role in malignant progression of most solid tumors, including colon, breast, head and neck, uterus, and stomach carcinomas. Two en-zymes COX-1 and COX-2 participate in the bio-synthetic pathway of PGE2. Increased levels of COX-2, represents the best target for therapeutic intervention. Administration of the non-steroid and anti-inflammatory drugs or the COX-2 inhibi-tors has been shown to reduce the overall number and size of adenomas in patients and also in ex-perimental animal models [18, 23, 24].
Scutellaria baicalensis extracts were shown to suppress PGE2 synthesis and inhibit COX-2 ex-pression in vitro in two head and neck tumor cell lines and inhibit head and neck tumor growth in vivo in mice.
It was also reported that wogonin, but not ba-icalein and baicalin inhibited lipopolyssaccharide (LPS)-induced COX-2 gene expressions in murine macrophages [25]. Wogonin was also shown to reduce COX-2 expression from murine skin fibro-blast NIH/3T3 cells, interleukin – 1β or TNFα and from human lung epithelial cancer cells [18]. The effect of wogonin on COX-2 was also examined in animal experiments which showed that it potently lowered mRNA levels of COX-2 in a sub-chronic and also in an acute skin inflammation model.
Chemokines and chemokine receptors partici-pate in inflammation and infection by stimulation of cell migration. Baicalein could inhibit binding of a number of chemokines to human leukocytes. This event led to reduction of chemokines to induce cell migration [26]. It was shown by Li et al. [26] that baicalin did not directly compete with chemokines for binding to receptors, but rather acted through its selective binding to chemokines of the CXC (strom-al cell-derived factor-1α, IL-8), CC (macrophage inflammatory protein-1β, monocyte chemotactic protein-2) and C (lymphotactin) subfamilies but not to the CX3C chemokine fractalkine/neurotac-tin or other cytokines, such as TNF-α and IFN-γ. Whether other flavones of Scutellaria sp. are also capable to bind chemokines to limit their biological function needs to be clarified.
Inhibition of Carcinogenic
Viruses by
Scutellaria baicalensis
Flavonoids
car-cinogens. Among them six viruses are cancerous for human: human papilomaviruses (HPVs) type 16 and 18, Epstein-Barr virus (EBV), two hepa-totropic viruses hepatitis B virus (HBV), hepatitis C virus (HCV), lymphotropic human T-cell virus type 1 (HTLV-1) and human immunodeficiency virus type-1 (HIV-1).
HTLV-1, and HIV-1 are oncogenic retrovi-ruses. HTLV-1 may cause adult T-cell leukemia/ lymphoma (ATLS) in small part of carriers of the virus.
Several types of cancer have been strongly as-sociated with the HIV-1 infection and developing acquired immunodeficiency syndrome (AIDS). Kaposi sarcoma, lymphoproliferative disorders and cervical cancer are observed in AIDS patients. HBV and HCV cause malignant disease of liver, hepatocarcinoma. EBV infection is associated with lymphoid and solid tissue malignancies including nosopharyngeal carcinoma, non-Hodgkins lym-phoma T cells and Hodgkin lymlym-phoma. Reverse transcriptase is a target for baicalin and baicalein inhibition of retroviruses replication in leukocytes [28, 29]. Sometimes, however, other stages of viral replication i.e. viral entry or release or HIV-1 pro-tease is inhibited by flavones [30–32]. Thus, fla-vones have been suggested by some investigators as potential anti-retroviruses agents.
Hepatocellular carcinoma (HCC) is one of the most frequent and malignant diseases worldwide. The major HCC risk factors are chronic HBV and HCV virus infections that attribute to HCC devel-opment in more than 80% of the HCC cases world-wide.
Effect of wogonin on HBV replication was studied in vitro in two human cell lines: MS-G2, producing cell line, and HepG2.2.15, HBV-transfected cells [33]. In both, suppression of virus was observed. In vivo suppression effect of wogonin was observed in duck infected with DHBV (duck hepatitis B virus) [34].
Another study aimed at seeking effective drugs against HCV screened 20 Chinese herbs and re-vealed five herbs, including Scutellaria baicalensis
with significant inhibitory effects on replication of HCV-RNA [35, 36].
Japanese authors Konoshima et al. [37] inves-tigated 14 flavones isolated from Scutellaria ba-icalensis for their inhibitory effects on the EBV early antigen (EBV-EA) activation. Among the flavones investigated 5,7, 2’-trihydroxy- and 5,7, 2’, 3’
-tetra-hydroxyflavone showed noticeable inhibitory effects on the EBV-EA activation. These flavones were also shown to inhibit skin tumor promotion in a two-stage carcinogenesis test in vivo in the mouse.
Antiviral activity of different agents (natu-ral plant or synthetic) may be expressed by their
virucidal effect, inhibition of viral replication in infected cells, stimulation antiviral nonspecific in-nate or specific immunity. The data presented here concerned the effect of flavones from Scutellaria baicalensis on replication of oncogenic viruses. The structure, taxonomic affiliation and mode of replication of the viruses are quite different. The results of flavones effect on replication of single virus are not repeatable. All the obtained results suggest that another mechanism, common for the different viruses might be engaged.
As it was suggested previously [27], the unspe-cific resistance of peripheral blood leukocytes (PBL) to viral infection maintained in vivo seems to fulfill requirement of the common mechanism against viruses. Flavones from Scutellaria were found to strengthen the resistance [17]. The leu-kocyte resistance is very important for course of not only viral, but also cancer disease. Acute leu-kemia is an example of cancer disease. Course of the disease and successive chemotherapy was fo-und to be dependent on degree of PBL resistan-ce [38]. Effective chemotherapy was obtained only in patients with resistant PBL. All patients with resistant PBL survived, while those with deficiency of resistance died in relatively short time. Zitvogel and Kroemer [39] in review on anticancer immu-notherapy present the possibility of participation some adjuvants in the therapy. The adjuvant, ho-wever, must have direct cytotoxic effect on cancer, anti-inflammatory effects and influence innate im-munity. As the flavones isolated from Scutellaria
express all the activities, they may be classified as adjuvant. Possible mode of the antitumor effect by adjuvant proposed by Zitvogel and Kroemer pre-sented in their publication indicate possible direct and indirect immune-mediated anticancer effects.
Molecular Mechanism
of Anti-Prostate Cancer
Activity of
Scutellaria
baicalensis
Extract and
Herbal Mixture PC-SPES
Management of prostate cancer that has spread beyond the capsule is a difficult problem. Innova-tive and non-toxic approaches to the disease are urgently required. Recently, a commercially avail-able Chinese herbal medicine called PC-SPES showed potent antitumor activites on a variety of malignant cells in vitro and in vivo in patients with advanced stages of the disease[6, 20, 40–42].
Moul), Panax pseudo-ginseng Wall., Glycyrrhiza uralensis Fisch, Rabdosia rubescens Hara, Scutel-laria baicalensis Georgi, Ganoderma lucidum
Karst, Isatis indigotica Fort, Serenoa repens Hook. – used by prostate cancer patients as an alterna-tive form of treatment. Since PC-SPES is derived from eight individual herbs, each with distinct as well as overlapping properties, it was interest-ing to investigate whether a particular herb in the formulation principally accounts for the biological properties of PC-SPES. Hsieh TC and Wu JM [40] tested the ability of extracts from individual herbs of PC-SPES on proliferation and prostate specific gene expression in androgen-dependent LNCaP cells, and synergism and antagonism among in-dividual herbal constituents of PC-SPES was ob-served. Chen at al. [20] have isolated a few of the most active compounds of ethanol extract of PC SPES. Among them, baicalin was the most abun-dant (about 6%) in the ethanol extract.
Recently, Adams et al. [41] investigated the interactions (the additive or synergistic effects) of botanical extract combinations of PC-SPES against the viabililty of prostate cancer cell lines. The most active extracts: S. baicalensis, D. mori-folium, G. uralensis and R. rubescens were tested as two-extract combinations. S. baicalensis and
D. morifolium when combined were additive with a trend toward synergy, D. morifolium and R. rube-scens together were additive. The remaining two-extracts combinations showed antagonism. The four extracts together were significantly more ef-fective than the two-by-two combinations and the individual extracts alone.
PC-SPES was evaluated for its ability to in-hibit clonal growth, and to induce cell cycle arrest of three human prostate cancer cell lines (LNCaP, PC-3, and DU 145). Western blot analysis exam-ined the effect of PC-SPES on levels of p21(waf 1), p27 (kip 1), Bcl-2 and E-cadherin in the three cell lines, and telomerase activity was examined by te-lomeric repeat amplification protocol (TRAP) as-say. Furthermore, the effect of oral administration PC-SPES (250 mg/kg/day) on growth of PC-3 and DU 145 tumors present in male BNX nu/nu triple immunodeficient mice was studied (LNCaP cells were not analyzed in mice because they grow only with difficulty in these immunodeficient mice) [42]. In results authors stated that PC-SPES mark-edly inhibited clonal growth of LNCaP, PC-3 and DU 145 prostate cancer cells, with a 50% inhibition (ED50) at approximately 2 μl/ml. Pulse-exposure studies showed that a 5-day pulse-exposure to PC-SPES (2 μl/ml) in liquid culture achieved a 50% inhibition of PC-3 clonal growth in soft agar, sug-gesting that the growth inhibition mediated by the extracts remained after removal of PC-SPES. Cell
cycle analysis using the prostate cancer cell lines found that PC-SPES induced a significant increase in the number of cells in G0-G1 and G2-M, with a concomitant decrease in the number of cells in 5 phase. PC-SPES (2 microl/ml, 4 days) increased slightly the levels of p21(waf1) in the three cell lines, decreases the levels of Bcl-2 in PC-3 by 40%, and the levels p27(kip 1) and E-cadherein and te-lomerase were unchanged in each of the lines. In vivo treatment with oral PC-SPES of male BNX mice having DU 145 tumors produced signifi-cant inhibition of their growth (p < 0.001), with no objective side effects including blood chemis-tries, weights, or autopsy analysis. The PC-SPES showed no statistical effect on the in vivo growth of PC-3 cells [42].
Molecular mechanisms of anti-prostate can-cer activity of Scutellaria baicalensis extracts was studied by Ye et al., too [43]. The goals of the study were to 1) determine its in vitro and in vivo
anti-prostate cancer activity, 2) investigate its molecular mechanism directed at cell prolifera-tion control including cyclooxygenase-2 (COX-2) prostaglandin E2 (PGE(COX-2), cyclins/cdks path-ways, and 3) compare it with those of PC-SPES (PC stands for prostate cancer and spes is Latin for hope), a former herbal mixture for prostate cancer treatment of which S. baicalensis is a ma-jor constituent. Two human prostate cancer cell lines (LNCaP, androgen dependent, and PC-3, androgen independent) were assessed for growth inhibition.
S. baicalensis exerted dose- and time-depen-dent increased growth inhibition in both cell lines. However, the PC-3 cells IC 50 (50% growth inhi-bition concentration) were slightly more sensitive than LNCaP (IC 50 = 0.15 mg/ml), although the former is androgen-independent, S. baicalensis
was more effective in inhibition of cell growth compared with PC SPES (IC 50 = 0.38 mg/ml for PC-3 cells). Significant reduction of PGE2 synthe-sis in both cells after treatment with S. baicalensis
resulted from direct inhibition of COX-2 activity rather than COX-2 protein suppression [40].
Scutellaria baicalensis also inhibited prostate-specific antigen production in LNCaP cells. Final-ly, S. baicalensis suppressed expression of cyclin D 1 in LNCaP cells, resulting in a G 1 phase arrest, while inhibiting cdk1 expression and kinase activ-ity in PC-3 cells ultimately leading to a G2/M cell cycle arrest [43].
to induce cell cycle arrest of various cancer types prostate cancer cell lines (PC-3, DU145, LNCaP), MCF-7 breast cancer cell line, HL-60 myeloblas-tic leukemia cell line, and NB4 promyelocymyeloblas-tic leu-kemia cell line. The ability of baicalin to induce apoptosis of cancer cells was examined by both staining with Annexin V and detection of cleav-age of Poly (ADP-ribose) polymerase (PARP). Western blot analysis examined the effect of ba-icalin on levels of p21 (waf 1) and p27 (kip 1) in those cells. Futhermore, induction of differenta-tion in HL-60 cells was measured by expression of CD 1 1 b. In results, baicalin inhibited the clonal proliferation of LNCaP and PC-3 prostate cancer cell lines, and the HL-60 and NB4 myeloblastic/ promyelocytic leukemia cell lines with a 50% in-hibition (ED 50) that ranged between 6,4 × 10 (-6) to 12 × 10 (-6) mol/L. Cell cycle analysis showed that baicalin (2 × 10 (-5) mol/L, 4 days) caused a G(0), G(1) and G(2)/M accumulation of LNCaP and HL-60 cells, respectively. Concomitantly, dif-ferentation and apoptosis were induced in HL-60 cells, as measured by expression of CD 11b anti-gen, staining with Annexin V, and detection of cleavage of PARP. Moreover, baicalin enhanced the expression of the cycldependent kinase in-hibitor, p27(kip 1) in LNCaP and HL-60 cells. In results, baicalin may be a novel adjunctive ther-apy for selected malignancies including prostate cancer, as authors suggested [44].
The Role of Flavonoids
of
Scutellaria baicalensis
in Human Breast Cancer
Cells
Baicalein inhibited the proliferation of es-trogen receptor – positive human breast cancer MCF-7 cells in vitro, with median effective con-centration 5.3 μg/ml [45].
Recently, baicalein was investigated for tumor cell-specyfic cytotoxicity, apoptosis inducing activ-ity and signal pathway against the MDA-MB-231 human breast cancer cell line [46]. After the MDA-MB-231 cells had been treated with baicalein, the dead cells and apoptosis was detected. The effects of baicalein on the levels of reactive oxygen spe-cies (ROS, Ca(2+) and mitochondrial membrane potential on MDA-MB-231 cells were examined by flow cytometric assays. The ROS caused endo-plasmic reticulum (ER) stress, confirmed by the increase of GADD153 and GRP78 in the examined cells (confirmed by confocal laser microscopy ex-amination) and indicated that both proteins were translocated to the nucleus.
The effects of baicalein on the expression of apoptotic-regulated genes, such as Bcl-2 family and caspase, were detected by Western blotting. The further investigate the apoptotic pathway and the role of Ca(2+) induced by baicalein, a cas-pase-3 inhibitor and Ca(2+) chelator were used to block caspase-3 activity and Ca(2+) in MDA-MB-231 cells. In conclusion authors stated that ba-icalein induced apoptosis via Ca(2+) production, mitochondria-dependent and caspase-3 activation in MDA-MB-231 cells [46].
Recently, Japanese authors Murashima et al. [47] demonstrated that the proliferation of es-trogen-responsive mouse Leydig tumor cell line B-1Fis induced via suppression of 5-lipoxygenase activity followed by decrease of leukotrienes (LTs). Additionally, it has been reported that LTD4 in-duces apoptosis in B-1F cells. In this study, authors examined effects of Saiboku-to (a traditional Japa-nese medicine KAMPO), which has suppressive activities for LT production and release, on the proliferation. Saiboku-to promoted, but Scutel-laria baicalensis (one of components of Saiboku-to), significantly inhibited the proliferation of B-1F cells in vitro and in vivo.
Role of Flavonoids of
Scutellariae baicalensis
Extracts in Human
Leukemia Cell Lines
Authors suggested that the inhibition of HL-60 cell growth is mediated partly through the induc-tion of Bax/Bcl-2 apoptosis and by telomerase inhibition through suppression of c-myc, which
is a promoter of hTERT. All these activities of
Scutellaria baicalensis extracts on leukemia cells are important in chemopreventive effects shown recently by Wang et al. [49].
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Address for correspondence:
Zofia Błach-Olszewska
Ludwik Hirszfeld Institute of Immunology and Experimental Therapy Polish Academy of Sciences
Rudolfa Weigla 12 53-114 Wrocław Poland
Conflict of interest: None declared
