The New Developments of Cantharidin and Its Analogues.
Summary: Canthiridin has significant anti-cancer effects and it is limited to be used due to its toxicity. While cantharidin causes some side effects such as hematochezia and tenesmus, it can efficiently inhibit various tumor cell lines, we must attach importance to it. Several its analogues show similar functions like cantharidin without highly toxicity. In order to utilize cantharidin to treat cancer, some viable methods are found to reduce its side effects. Cantharidin can inhibit the activity of protein phosphatases, new researches for the inhibition of protein phosphatases have been implemented.
Key words: Canthiridin, Cancer, Toxicity, Inhibition, Analogues, PPs.
The use of the dried body of the Chinese blister beetle, Mylabris (Fig. 1), can be traced back more than 2000 year in traditional Chinese medicine . It has been categorized as highly toxicant in Chinese medicine. Cantharis patches have been used since ages to treat various skin-related diseases. Cantharidin (exo, exo-2, 3-dimethyl-7-oxobicyclo [2.2.1] heptane-2, 3-dicarboxylic acid anhydride) (structure in Fig.2), is extracted from the Chinese blister beetles. Cantharidin can efficiently treat molluscum contagiosum, a common cutaneous viral inflection. Cantharidin shows its toxicity to arthropods: Diptera, Hymenoptera, Homoptera, Lepidoptera and Acarina . It has been found to affect Children and adolescents . Cantharidin's toxic effects have caused it to fall into disuse for most legitimate medical purposes. These effects include gastrointestinal, dermatologic, genitourinary, cardiac, pulmonary, hematologic effects.
It's reported that cantharidin causes patient's hematochezia and tenesmus. Skin in touch with cantharidin causes mild irritation and inflammation . For cardiac, the most common symptom is sinus tachycardia . Although cantharidin generates these effects, its advantages must be realized. Cantharidin can inhibit various tumor cell lines. Cantharidin treated cancer recorded for the first time was by Yang Shi-Ying who is a physician. It has been found that potent antitumor effects at the dose of 0.5 mg/Kg body weigh/day. Cantharidin is a kind of effective pesticide, and proves highly toxic to many insects, especially lepidopteran [6, 7]. Certainly, the most important function of cantharidin is resisting cancer. In various kinds of cancer cells, cantharidin can cause apoptosis and double-stand breakage of DNA . While cantharidin is quite useful, unfortunately, due to its side effects, increasing regulations have limited access to this useful therapeutic option.
Doctor must know its potential toxicities, including painful, even fatal, systemic reactions . Recently, cancer affects people's life more and more, however, cantharidin can treat hepatoma, breast cancer, and lung cancer and so on, we must study more on cantharidin. While cantharidin possesses some serious toxicity, several its derivatives with low toxicity can play a similar role, so more works must be implemented to decrease toxicity. In the next section, after a statement of the basic problem, a short review of cantharidin and its analogues follows. I will introduce from three aspects: 1. several analogues of cantharidin and some studies related to them; 2. several efficient methods to inhibit the side effects of cantharidin; 3. pharmacogenomics of cantharidin.
Because cantharidin has many side effects, for example, dysphagia, liver congestion and renal toxicity, the application of it is limited . Therefore, scientists make an effort to find solution to reduce toxicity. And its analogues show some similar functions to cantharidin, for example, norcantharidin and cantharidin have anti-metastatic effect via suppressing expression of MMP-9 through Sp1 pathways [11, 12]. The modified cantharidin analogues reduce toxicity in hepatocytes . So studies of cantharidin's analogues are getting more urgent.
Norcantharidin (7-oxabicyclo [2.2.1] heptane-2, 3-dicarboxylic anhydride) (Fig.3) is a new type of lower toxicity of anticancer drugs which was extracted and synthesized from traditional Chinese medicine. Norcantharidin, a chemically demethylated analog of cantharidin which possesses anti-cancer activity. Norcantharidin is less cytotoxic than cantharidin and was used to treat cancers in China since 1984. Norcantharidin is an antitumor drug and is suitable for liver cancer gastric cancer, hepatitis, cirrhosis and low white blood disease, and its main mechanism is to inhibit tumor cell. Because of its important function, many investigates have been carried out. Xianqian Li et al. reviewed norcantharidin-induced tumor cell apoptosis. When the multiplication and apoptosis of normal cells lose balance, the apoptosis is hinder, or multiplication exceeds apoptosis, the tumor cell will grow. Norcantharidin can restrain tumor cell from multiplication and induce the apoptosis of tumor cell.
Some people found that gastric cancer cells SGC-7901, primary gallbladder GBC-SD department of cell, respectively [14, 15]. Research shows that norcantharidin can change tumor cell's certain gene's expression [12, 16-19].While using norcantharidin to dispose human liver BEL-7402 cells, they find norcantharidin can suppress the activation of NF-KB which protects the tumor cells by inhibiting cell apoptosis [20, 21].
A series of novel acylthiourea derivatives of cantharidin were designed and synthesized as biorational pesticides. Mei Juan Wang et al. firstly introduced the acylthiourea group to cantharidin via a coupling reaction in order to study their insecticidal/acaricidal activity. They carried on acaricidal assay against Tetranychus cinnabarinus and insecticidal assay against Brevicoryne brassicae. These compounds show significant resistance activity against them with LC50 values ranging from 0.695 to 2.934 mmol/L. Among these compounds, N-[(3-Bromobenzoylthioureido) ethyl] cantharidinimide (2a) and N-[(3-Chlorobenzoyl-thioureido) ethyl] cantharidinimide (2b) (structures in Fig.4) shows the strongest acaricidal effect . As listed in Table-2, it inhibited that biological activity of compounds 2a and 2b against T. cinnabarinus and B. brassicae in vivo at 1 day concentrate.
Cantharidinamides are developed as a new cantharidin's analogues. In Adam McCluskey's report, cantharidinamides have better inhibition of PP1 and PP2A than norcantharidin. And they have a d- or l-histidine . Ji-Yeon Lee et al. research a novel cantharidin analogue N-benzylcantharidinamide which has an anti-invasive activity on hepatocellular carcinoma and has low cytotoxicity . Cancer invasion and metastasis are major causes for mortality associated with malignant tumor . The present study investigates the inhibitory effect of N-benzylcantharidinamide (structure in Fig.5) on matrix metalloproteinase-9 (MMP-9)-mediated invasion in metastatic hepatocellular carcinoma Hep3B cells. In study, N-benzylcantharidinamide was used for this experiment at 30 uM, results showed that N-benzylcantharidinamide showed significant inhibitory effect on the activity of MMP-9. MMP-9 can control cell growth, migration, and angiogenesis via in a non-enzymatic manner.
N-benzylcantharidinamide suppresses the MMP-9 expression and invasion of Hep3B cells in a dose-dependent manner . N-benzylcantharidinamide inhibits MMP-9 activity by two main ways: direct enzymatic inhibition and expressional regulation. N-benzylcantharidinamide decrease the stability of MMP-9 mRNA to inhibit the expression of MMP-9 without inhibiting the transcriptional activity of MMP-9. Experimental results show that N-benzylcantharidinamide inhibit MMP-9 by down-regulation of MMP-9 expression at mRNA levels. Therefore, it is declared that N-benzylcantharidinamide will be value in preventing MMP-9-mediated cancer invasion and metastasis.
A series of cantharidin analogues which have been anhydride-modified have been synthesized. Adam McCluskey et al. reported that ring opening of the anhydride moiety of cantharidin formed diacid. Its ability of inhibiting PP2A was declined. 
Wenbo Sun et al. explored two series of cantharidin anhydride-modified derivatives containing alkyl and aryl groups, respectively, what determines the insecticidal activity structurally of cantharidin-related compounds. These compounds were characterized by 1H-NMR, 13C-NMR and HRMS-ESI. Among these compounds, compound which has a nitrophenyl (Fig.6) showed highest insecticidal activity with LC50 value of 0.43 mM. It shows that the improvement of pesticidal activity required a reasonable combination of both aliphatic amide and aromatic amide moieties, and the species of substituent Y on the aniline ring was necessary .
Sodium Cantharidate (SCA) is a kind of CTD's analogs and its toxicity is lower. And it can significantly reduce the side effects of urinary system. When cantharidin and sodium hydroxide heat together, SCA is produced. Experiments show that treating with SCA after 72 hours, the number of cancer cells significantly reduce. And the count of white blood cell increases. N-methylcantharidimide is another CTD's analog. It can inhibit a variety of animals' transplanted tumors and anti-tumor spectrum is wide. It mainly is used in primary liver cancer. Main mechanism of action is interfering nucleic acid and protein synthesis, thereby it inhibits the growth of tumor cells and reproduction; at the same time, and it can enhance macrophage phagocytosis and inhibit antibody production and has an impact on immune function. N-hydroxycantharidimide is used to treat primary liver cancer. It can inhibit animal tumor. Clinical observations, its effect rate of liver cancer were 54.5%. But it has an impact on the urinary system.
Table-1: The inhibition of cantharidin and norcantharidin for several substances with IC50uM(50% of enzyme activity) [2. 68]
Compounds###PP1###PP2###PP5###rPxPP5(recombinant P.xylostella PP5)###A.thalianaPSP
Compounds###L.paucicostata###P.xylostella PSP###rEcPP5(recombinant encoding PP5)###CCRF-CEM
Table-2: Biological activity of compounds 2a and 2b against T. cinnabarinus and B. brassicae.
Compounds###T. cinnabarinus###LC50(mmol/L)###B. brassicae###LC50(mmol/L)
###Mortality (%)###Mortality (%)
Cantharidin consists of a six-ring and a five-ring (Fig.2), the moiety of oxygen on the six-ring and the anhydride section exhibit biochemical activity. Removing two methyl groups from cantharidin, norcantharidin is obtained, and for PP2B, norcantharidin shows stronger inhibitory and also shows intense activity on tumor cells. When cantharidin and its analogs combine with the catalytic site of the PP5C, their anhydride rings will be hydrolyzed. Sulfur atom or nitrogen atom can replace the oxygen atom between the two carbonyl groups, such as cantharimides, which have a D- or L-histidine, can suppress a lot of tumor cells. [29-32]
Inhibition of protein phosphatases (PPs) by cantharidin
Protein phosphatases are associated with many cellular processes including apoptosis, cell cycle progression and so on. In the past years, cantharidin has been showed to inhibit the activities of protein phosphatase 1 and protein phosphatase 2A (PP1 and PP2A) [33, 34]. Cantharidin and norcantharidin can efficiently inhibit the activity of mammalian and plant protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) in vivo. Of course, other protein phosphatases, such as PP3, PP4, PP5, PP6, PP7, may also be suppressed by cantharidin. In Rolf Rauh et al. study, they found that cantharidin and norcantharidin can inhibit PP1 and PP2A.They analyzed the microarray database of the National Cancer Institute for identifying the molecular determinants that predicted sensitivity or resistance of tumor cells to cantharidin. They found that 21 genes which were included in 9706 genes showed highest correlation coefficients to IC50, its mRNA expression was in 60 tumor cell lines.
21 identified genes are involved in DNA damage response, DNA repair and apoptosis . In cantharidin-induced apoptosis' regulation, the tumor inhibitors p53 and p21, the bcl-2 proteins, the JAK/STAT pathway and the transcription factor NF-KB are important . There are also other studies for this. Chao Zhang et al. showed that cantharidin can induce cell apoptosis by inhibiting PP2A. They found an analogue of cantharidin, LB1, which is a water soluble homolog, can inhibit PP2A without apparent toxicity. Chao-Bin Yeh et al. study showed that cantharidin analogues which had different structure will demonstrate different inhibitive ability. Cantharidin ramification which was modified by dehydration can increase inhibition of PP2A.
Recently, new researches for inhibiting PP5 also were studies. PP1, PP2A, PP4, PP5 et al. are included in the PPP family. PP5 is a special member in this family. PP5 can be considered as therapeutic target and a proper common representative to study how cantharidin and its analogues inhibit PPP. Cantharidin inhibits PP5 at the nanomolar level with an IC50 value of 600 nM. PP5 shares 35-45% sequence identity in the catalytic domain with other PPP families. Two manganese ions and ten catalytic residues belong to PP5 as the active center. PP5 can regulate the dynamic phosphorylation of some signaling components, such as p53, apoptosis signal-regulating kinase 1 (ASK-1) . In human breast cancer, people found that the expression levels of PP5 were raised . These all indicated that PP5 can be treated as a novel target in anti-cancer therapies .
Ji-Yuan Liu et. al worked to reveal the important interactions between PP5 and three inhibitors including cantharidin, norcantharidin and endothall at the atomic level . In their study, they applied molecular dynamics (MD) simulations and site-directed mutagenesis to uncover how cantharidin and its analogs bind to PP5c (The catalytic domain of PP5). MD can help deeply understand the structure and dynamics of proteins at the atomic lever. They found that Arg100 contributed less to PP5-inhibitor binding while the residues His69, Asn128, His129, Arg225, His252 and Arg250 contributed more to PP5-inhibitor binding. To build the hydrophobic interactions between the residues Phe271, Glu253, Val254 and Tyr276 can enhance the inhibition. Their study can also help to develop less cytotoxic anti-cancer drugs. Xi'en Chen et al. found that cantharidin had inhibitory effects on protein serine/threonine phosphatases (PSPs) of plutella xylostella in vivo and in vitro.
In Escherichiacoli, recombinant PxPP5 (rPsPP5) was expressed and purified. They performed the rPsPP5 activity inhibition assay with cantharidin and its 11 analogues. They all inhibited rPxPP5 activity. Results showed that rPxPP5 activity was obviously inhibited by cantharidin with an IC50 of 0.38uM. Other analogs also could inhibit its activity with an IC50 of 7.42-538.38uM. They got kinetic properties of rPxPP5 to phosphopeptides with 0.1uM cantharidin and 1.0uM norcantharidin. The Lineweaver-Burk plot showed that rPxPP5 could be inhibited competitively by cantharidin and norcantharidin. The inhibition effect demonstrated that cantharidin and norcantharidin could combine with the active site of rPxPP5. They thought that other analogs could also impede rPxPP5 . Superimposing the 3D models of catalytic domains of five PxPSPs showed the high possibility that these compounds inhibited other PxPSPs .
So they concluded that these compounds displayed their main mechanism of insecticidal activity after they inhibited protein serine/threonine phosphatases activity in P.xylostella. In Xi'en Chen et al. another article, identification and biochemical characterization of protein phosphatase 5 from the cantharidin-producing blister beetle, Epicauta chinensis, showed that they obtained a cDNA fragment from the blister beetle, E.chinensis, which can produce cantharidin and study its identification and characterization. PP5 was encoded by various genes. There was a special structure in PP5, at the C-terminal half of protein, it had a conserved catalytic serine/threonine phosphatases domain and at N-terminal extension, it had three to four tetratricopeptide repeat (TPR) domains. They can bind to unsaturated fatty acids to influence the activation of PP5 . The purified PP5 can show a low basal activity.
PP5 can manage the cellular survival, death, proliferation and other some intracellular biological activities in mammals . EcPP5 included an open reading frame of 1500 bp that encoded a protein of 56.89KDa. In Escherichia coli, the recombinant EcPP5 (rEcPP5) was produced and purified. The purified rEcPP5 showed phosphatase activity towards pNPP (p-nitrophenyl phosphate) and phosphopeptides. There were four substances, okadaic acid, cantharidin, norcantharidin and endothall strongly inhibited rEcPP5 activity. They found that PPP activity could be impeded by these four inhibitors, this indicated some protection mechanism can protect this beetle when it may be damaged due to its cantharidin. In some scientists' article, they assessed the roles of PP5 of second-generation merozoites in Eimeria tenella in the anticoccidial activity of TEM and quantitative real-time PCR were used to monitor the ultrastructural changes of EtPP5.
There was a C-terminal repeat part which was a representative point of protein phosphatases. After diclazuril treatment, the level of EtPP5 mRNA expression was downregulated. In the diclazuril-induced merozoites apoptosis, EtPP5 could help us to understand the signaling mechanism .
The Inhibition of Cantharidin on Glutathione S-Transferases (GSTs)
Glutathione S-Transferases (GSTs) are the key enzyme of glutathione and they have various forms. GSTs can catalyse xenobiotics, including eliminating the toxicity of pesticides . GSTs are dimeric proteins. GSTs have detoxification of xenobiotics in organisms , thus, they can deal with the toxicity from cantharidin. GST is a main reason for resisting insecticide and it can protect proteins and nucleic acid. GST participates in the process of xenobiotic detoxification and the detoxification of endobiotic compounds. Therefore, cantharidin must inhibit GSTs when it was used to be insecticide in order to prevent metabolic detoxification by insects. Xue-Qing Yang and Ya-Lin Zhang studied three kinds of GSTs: Sus scrofa GST (SsGST[alpha]1), Cydia pomonella GST (CpGSTd1) and Triticum aestivum GST (TaGSTf3). They all have typical C-terminal and N-terminal domains.
They found that cantharidin strongly inhibited the activity of CpGSTd1 and had no influence on SsGST[alpha]1, but it obviously promoted the activity of TaGSTf3 with an EC50 value of 0.3852mMol . Rashid Ahmed Khan et al. investigated the effect of cantharidin on mRNA transcript of H.armigera GST (HaGST). They got a soluble recombinant protein rHaGST. By biochemical assays, they found the inhibition of cantharidin on GSTs in vivo and the inhibition on rHaGST in vitro. By molecular docking simulations, cantharidin molecule docked accurately with the active site of HaGST, so the catalytic activity of GST was inhibited. These all indicated that cantharidin can potently inhibit the GSTs in vivo and the HaGSTs in vitro .
Other Several Functions and Inhibitions
In Ting Wang, Jian Liu and Xiao-Qin Xiao investigation, they studied how cantharidin inhibited angiogenesis. In their study, datas indicated that cantharidin could impede the activity of angiogenesis forcefully in a dose-dependent way. Cantharidin inhibited the multiplication, migration and formation in tube in vitro of human umbilical vascular endothelial cells and inhibited angiogenesis in chick embryo in vivo. They found that cantharidin could abolish the activity of STAT3 induced by VEGF at the molecular level and it could suppress the phosphorylation of AK1, ERK and JAK1. These all showed that cantharidin could inhibit the growth factor of angiogenesis. They also found that norcantharidin was an agent of anti-tumor angiogenesis by inhibiting the multiplication, migration and formation in tube in a dose-dependent way. Norcantharidin block VEGFR2/MEK/ERK signal pathways to show this function. In a word, cantharidin can potently inhibit angiogenesis in vitro and in vivo .
Youngmin Kim et al. reported that cantharidin can show anti-metastatic effect on A549 human lung cancer cells. If tumor cells migrate, extracellular matrix (ECM) will degenerate. They found cantharidin can inhibit the activation of the phosphaticlylinositol 3-kinase/AKt (PI3K/AKt) signal pathway. The PI3K/AKt plays an important role in the cancer development. This can degrade the ECM and inhibit metastasis of A549 human lung cancer cells . Recently, Kousi Alzoubi et al. reported that cantharidin could trigger eryptosis similar to apoptosis of tumor cells. Eryptosis can be triggered by many xenobiotics [51-53]. They obtained erythrocytes from healthy volunteers and exposed them to cantharidin. Eryptosis has several signals includes oxidative stress, ceramide, increase of cytosolic Ca2+-activity and dysregulation of several kinases .They found that cantharidin increased the percentage of annexin-V-binding cells, decreased forward scatter and increased cytosolic Ca2+-activity.
Cantharidin induced the suicidal erythrocyte death . The inhibitory effects of cantharidin for pancreatic cancer cells and bladder cancer cells were reported recently. Meng Shen et al. observed that cantharidin could inhibit pancreatic cancer cells to invade and downregulate the expression of matrix metalloproteinase 2 (MMP2). They found that cantharidin inhibited PP2A in pancreatic cancer cells and this caused phosphorylation of many substrates, such as protein kinase C (PKC), [beta]-catemin, JNK and IKB kinase (IKK). They explored if cantharidin regulated invasion and the expression of MMP2 in these pathways in pancreatic cancer cells . In recent study, Chin-Chuan Su et al. reported that cantharidin induced bladder cancer cell apoptosis through a calcium/PKC-regulated endoplasmic reticulum (ER). Cantharidin could decreased cell viability and increased caspase-3 activity in bladder cancer T24 cells.
Cantharidin could increase the intracellular Ca2+ and the phosphorylation of protein kinase C (PKC) in T24 cells. They found that cantharidin obviously decreased the tumor volume in mice . These all indicated that cantharidin was a kind of novel anticancer agent for treating pancreatic cancer and bladder cancer.
Mechanism of Action-as Proposed by Different Schools
CTD has obviously anticancer effects. It can cause apoptosis and break DNA double strand . And CTD's mechanism of action in the human body mainly reflects in that it can inhibit the activity of PP1 and PP2A in kinds of cancer cells, so it affects apoptosis. CTD also can influence the synthesis of protein . NCTD can induce cell apoptosis by lowering expression of NF-KB gene to show its antitumor function. NCTD can suppress the biological activity of tumor cell. Study shows that NCTD can obviously demonstrate inhibition of mitosis and the synthesis of DNA of white blood disease HL60 cell. NCTD is potent serine/threonine protein phosphatase 1 and protein phosphatase 2A (PP1 and PP2A) inhibitors. If PP1 is suppressed, cycle protein RB cannot perform dephosphorylating, and then the block of G2/M appears. If PP2A is smothered, it may promote to go over G2-M and detection point and abnormal mitosis will be present, in the end, cell's apoptosis occurs.
NCTD has function of increasing white blood cells. It can stimulate rat's bone marrow and generate the cell factors of hemameba interleukin-1[beta], TNF-[alpha] and ring spore. Due to NCTD' important effect, it will play a more important role in the treatment of tumor cell.
Novel Strategies and New Directions
Cantharidin is a promising anticancer drug, but because of its toxicity for human, it is limited to be put to use. But its efficiency is obvious to resist cancer, so we must find methods to inhibit its side effects. Thus, cantharidin, as a poisonous agent, its adverse effects must be decreased before it is safely he used to treat cancer. Using some analogues of cantharidin is workable. Recently, some other efficient methods or substances can play similar role. I propose a combination strategy like using Vitamin C and ginsenosides to minimize the cantharidin side effects in the patients. Next, I will introduce several novel methods which can reduce toxicity of cantharidin.
Vitamin C (VC)
VC is beneficial for human and has positive advantages, such as prevention of metabolic disease or cancer. VC has been researched as an efficient hepatoprotective agent against liver damage. The functions of VC mainly reflect as follows: reducing liver enlargement; lowering the count of intrahepatic TNF-[alpha] positive cells; down-regulating the mRNAs of TLR4 and NF-KB pro-inflammatory mediators; lowering serum concentrations of glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase(GOT); decreasing the level of IKE's phosphorylation in the hepatocytes . In a study, mice treated by cantharidin suffered from liver expansion and body weight loss and it indicated that the mice was sick due to cantharidin-induced hepatic impairments. Using VC for mice generated alleviated hepatomegaly, this suggested that VC can treat some symptoms, such as weakening liver tissue edema and vascular congestion.
Cantharidin can reduce intrahepatic Na+-K+-ATPase, SOD, and GSH-Px concentrations while VC co-treatment can inhibition these cantharidin-induced damage [60, 61]. Some researchers found that cantharidin could cause abnormal up-regulation of intrahepatic TNF-[alpha], NF-KB, p-IKB and TLR4. While VC could efficiently inhibit abnormal expressions of regulatory gene/protein. In short, these all shows that VC can reduce the liver damage that cantharidin causes. Because VC has these advantages, its value must be more developed and utilized.
Ginsenoside is the major active ingredient of ginseng. Ginseng is considered as a kind of greatly beneficial medicine in China. It is helpful for people's body. It was reported that ginsenosides have antidiabetic, anti-inflammatory, antitumor activities, antiatheroscloresis effects and antitumor anticomplement activity in recent years . And ginsenosides have been used to treat renal disease. Qiongming Xu et al. studied protective effects of gingenosides on acute renal injury induced by cantharidin in vitro and in vivo. In a study, cantharidin decreased viability of NRK cell ranging from 72.22% to 9.97%. Ginsenosides inhibited decreasing viability of NRK cell. This suggests that ginsenosides can protect NRK cell. There was an experiment for inhibiting the toxicity which was caused by cantharidin in rat's normal kidney NRK cell, this demonstrated good inhibition. Cantharidin can cause the apoptosis of NRK cell, and decrease the expression of bcl-2.
The bcl-2 is antiapoptosis-related factor. The most serious side effect of cantharidin for renal is that it promotes renal tubular epithelial cell apoptosis by reducing the expression of bcl-2. However, ginsenoside showed inverse action. After using cantharidin (0.14mg/Kg) for 15 days to rats, rats suffered from renal injury. The levels of serum creatinine, urine protein and urea nitrogen were increased, but ginsenosides decreased. It was found that ginsenosides could avoid ischemia and contralateral nephrectomy. A study showed that 20(S)-ginsenoside Rg3 could obviously weaken the renal dysfunction of diabetic rats in a dose-dependent manner . In a word, ginsenosides can be used to resist renal injury caused by cantharidin by inhibit apoptosis. Therefore, ginsenosides can be used to decrease certain side effects related to cantharidin . Nowadays, it is not clear whether it can protect other drug- or toxin-induced renal injuries.
Translating Cantharidin into Nanoparticles
Cantharidin has been found that it can inhibit colorectal cancer cells. Colorectal cancer has become the second leading cause of death in cancer patients in the US . It has been found that cantharidin can efficiently oppose some colorectal cancer cells. However, cantharidin has showed serious side effects such as dysuria. Thus, a relevant method is needed to solve the trouble. Translating cantharidin into nanoparticles as a drug delivery, the side effects of cantharidin can be significantly decreased and its potency also can be increased. For example, this method can affect folate which can influence tumor cell's multiplication and survival. Folate receptor is over-expressed in ovarian cancer, breast cancer and so on . Folic acid has been conjugated to many delivery systems for cancer therapy.
Cantharidin loaded nanoparticles can increase the cytotoxicity of cantharidin on the folate over-expressed HT-29 cells; moreover, introducing folate to the nanoparticles can further increase its efficacy . In general, cantharidin loaded nanoparticles can show better potency and this method will perform more potency.
As cancers become more severe, appropriate therapeutic agents increasingly become urgent need.Cantharidin can inhibit various tumor cell lines. Cantharidin causes both DNA single- and double-strand breaks and induces apoptosis. Although cantharidin shows some toxicity for human, its anti-cancer effects should be taken seriously. Several viable methods can help solve this problem such as translating cantharidin into nenoparticles. And its some analogues have been synthesized without highly toxicity. Norcantharidin is a good anticancer drugs with low toxicity and it can be extracted and synthesized from traditional Chinese medicine. The most important pharmacogenomics of cantharidin is that cantharidin can inhibit PPs. Because PPs are associated with many cellular processes, so researches on this area is necessary. Scientists have researched PP1, PP2A, PP5 etc., and more studies are also necessary for other PPs such as PP6, PP7. This prospect is very broad and needs to continue studying.
This study was financially supported by Zhejiang Provincial Natural Science Foundation of China under Grant (No. LQ13H300001) and by the National Science Foundation for Young Scholars of China under Grant (No. 81202411). The authors also thank Prof. Yongzhou Hu of Zhejiang University for helping providing experiment facilities.
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|Author:||Wang, Guofang; Wang, Wei; Wu, Chunlei; Hu, Chunqi; Deng, Liping|
|Publication:||Journal of the Chemical Society of Pakistan|
|Date:||Aug 31, 2017|
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