Penta-acetyl geniposide-induced C6 glioma cell apoptosis was associated with the activation of protein kinase C-delta

Genipin's potential as an anti-cancer agent: from phytochemical origins to clinical prospects

This comprehensive review delves into the multifaceted aspects of genipin, a bioactive compound derived from medicinal plants, focusing on its anti-cancer potential. The review begins by detailing the sources and phytochemical properties of genipin, underscoring its significance in traditional medicine and its transition into contemporary cancer research. It then explores the intricate relationship between genipin's chemical structure and its observed anti-cancer activity, highlighting the molecular underpinnings contributing to its therapeutic potential. This is complemented by a thorough analysis of preclinical studies, which investigates genipin's efficacy against various cancer cell lines and its mechanisms of action at the cellular level. A crucial component of the review is the examination of genipin's bioavailability and pharmacokinetics, providing insights into how the compound is absorbed, distributed, metabolized, and excreted in the body. Then, this review offers a general and updated overview of the anti-cancer studies of genipin and its derivatives based on its basic molecular mechanisms, induction of apoptosis, inhibition of cell proliferation, and disruption of cancer cell signaling pathways. We include information that complements the genipin study, such as toxicity data, and we differentiate this review by including commercial status, disposition, and regulation. Also, this review of genipin stands out for incorporating information on proposals for a technological approach through its load in nanotechnology to improve its bioavailability. The culmination of this information positions genipin as a promising candidate for developing novel anti-cancer drugs capable of supplementing or enhancing current cancer therapies.

Gardenia jasminoides Enhances CDDP-Induced Apoptosis of Glioblastoma Cells via AKT/mTOR Pathway While Protecting Death of Astrocytes

Gliomas are the most observed primary brain tumor, of which glioblastoma multiform (GBM) shows the highest incidence. Radiotherapy with temozolomide is the standard therapeutic method, but because of side effects, search for alternative therapies is required. Gardenia jasminoides (GJ) is flavonoid abundant with beneficial effects on inflammation, metabolic diseases, and cancers. In this study, we investigated the synergistic combination of GJ and cisplatin (CDDP) in U87MG and U373MG GBM cells. GJ and CDDP both showed cytotoxicity in U87MG cells, however GJ did not affect viability of normal astrocytes while CDDP displayed high toxicity. Cytotoxic effect of GJ and CDDP was related in apoptosis when confirmed by Western blot assays on cleaved caspase-3, caspase-9, and PARP. Moreover, GJ and CDDP showed synergistic combination in cell death of GBM cells, which was further confirmed by Western blot assays of apoptosis factors and also flow cytometry of Annexin V. Analysis on autophagy factors showed that GJ/CDDP combination induced autophagy, and through inhibition of autophagy, we could confirm autophagy is crucial to cytotoxicity of GJ/CDDP in GBM cell lines. The autophagy-mediated apoptosis of GJ/CDDP was dependent on the AKT/mTOR pathway. Overall, our results suggest GJ/CDDP combination as an effective yet safe therapeutic approach to GBMs.

Therapeutic Potential and Effective Components of the Chinese Herb Gardeniae Fructus in the Treatment of Senile Disease

Gardeniae fructus (GF), an evergreen Rubiaceae shrub, is one of the most commonly used Chinese herbs in traditional Chinese medicine (TCM) and has been used for over a thousand years. It is usually prescribed for the treatment of brain aging, vascular aging, bone and joint aging, and other age-related diseases. It has been demonstrated that several effective compounds of GF, such as geniposide, genipin and crocin, have neuroprotective or related activities which are involved in senile disease treatment. These bioactivities include the mitochondrion dysfunction, antioxidative activity, apoptosis regulation and an anti-inflammatory activity, which related to multiple signaling pathways such as the nuclear factor-κB pathway, AMP-activated protein kinase signaling pathway, and the mitogen-activated protein kinase pathway. To lay the ground for fully elucidating the potential mechanisms of GF in treating age-related pathologies, we summarized the available research conducted in the last fifteen years about GF and its effective components, which have been studied in vivo and in vitro

Potential role of genipin in cancer therapy

Genipin, an aglycone derived from the iridoid glycoside, geniposide, is isolated and characterized from the extract of Gardenia jasminoides Ellis fruit (family Rubiaceae). It has long been used in traditional oriental medicine for the prevention and treatment of several inflammation driven diseases, including cancer. Genipin has been shown to have hepatoprotective activity acting as a potent antioxidant and inhibitor of mitochondrial uncoupling protein 2 (UCP2), and also reported to exert significant anticancer effects. It is an excellent crosslinking agent that helps to make novel sustained or delayed release nanoparticle formulations. In this review, we present the latest developments of genipin as an anticancer agent and briefly describe its diverse mechanism(s) of action. Several lines of evidence suggest that genipin is a potent inhibitor of UCP2, which functions as a tumor promoter in a variety of cancers, attenuates generation of reactive oxygen species and the expression of matrix metalloproteinase 2, as well as induces caspase-dependent apoptosis in vitro and in in vivo models. These finding suggests that genipin can serve as both a prominent anticancer agent as well as a potent crosslinking drug that may find useful application in several novel pharmaceutical formulations.

Plant-Derived Anticancer Agents: Lessons from the Pharmacology of Geniposide and Its Aglycone, Genipin

For centuries, plants have been exploited by mankind as sources of numerous cancer chemotherapeutic agents. Good examples of anticancer compounds of clinical significance today include the taxanes (e.g., taxol), vincristine, vinblastine, and the podophyllotoxin analogues that all trace their origin to higher plants. While all these drugs, along with the various other available therapeutic options, brought some relief in cancer management, a real breakthrough or cure has not yet been achieved. This critical review is a reflection on the lessons learnt from decades of research on the iridoid glycoside geniposide and its aglycone, genipin, which are currently used as gold standard reference compounds in cancer studies. Their effects on tumour development (carcinogenesis), cancer cell survival, and death, with particular emphasis on their mechanisms of actions, are discussed. Particular attention is also given to mechanisms related to the dual pro-oxidant and antioxidant effects of these compounds, the mitochondrial mechanism of cancer cell killing through reactive oxygen species (ROS), including that generated through the uncoupling protein-2 (UCP-2), the inflammatory mechanism, and cell cycle regulation. The implications of various studies for the evaluation of glycosidic and aglycone forms of natural products in vitro and in vivo through pharmacokinetic scrutiny are also addressed.

Discovery of Glycosylated Genipin Derivatives as Novel Antiviral, Insecticidal, and Fungicidal Agents

A series of novel genipin glycoside derivatives incorporating 11 glycosidic moieties at either the 1 or 10 position of genipin were designed and synthesized. These compounds exhibited moderate to excellent inhibitory activities against tobacco mosaic virus. Especially, the in vitro and in vivo activities of compounds 6e, 7c, 7d, 7f, 7h, and 7i were comparable to that of ribavirin. In particular, compound 7c, the mannosyl derivative of genipin at the 10 position, showed the best activity. The series of genipin glycosyl derivatives also displayed fungicidal activities against 14 kinds of phytopathogenic fungi, especially for Rhizoctonia cerealis and Sclerotinia sclerotiorum. Moreover, compound 6h exhibited good insecticidal activity against diamondback moth; compounds 7b, 7c, and 7g exhibited moderate insecticidal activity against three kinds of Lepidoptera pests (oriental armyworm, cotton bollworm, and corn borer); and compound 7e showed excellent larvacidal activities against mosquito.

UCP2- and non-UCP2-mediated electric current in eukaryotic cells exhibits different properties

Using live eukaryotic cells, including cancer cells, MCF-7 and HCT-116, normal hepatocytes and red blood cells in anode and potassium ferricyanide in cathode of MFC could generate bio-based electric current. Electrons and protons generated from the metabolic reaction in both cytosol and mitochondria contributing to the leaking would mediate the generation of electric current. Both resveratrol (RVT) and 2,4-dinitrophenol (DNP) used to induce proton leak in mitochondria were found to promote electric current production in all cells except red blood cells without mitochondria. Proton leak might be important for electric current production by bringing the charge balance in cells to enhance the further electron leak. The induced electric current by RVT can be blocked by Genipin, an inhibitor of UCP2-mediated proton leak, while that induced by DNP cannot. RVT could reduce reactive oxygen species (ROS) level in cells better than that of DNP. In addition, RVT increased mitochondrial membrane potential (MMP), while DNP decreased it. Results highly suggested the existence of at least two types of electric current that showed different properties. They included UCP2-mediated and non-UCP2-mediated electric current. UCP2-mediated electric current exhibited higher reactive oxygen species (ROS) reduction effect per unit electric current production than that of non-UCP2-mediated electric current. Higher UCP2-mediated electric current observed in cancer cells might contribute to the mechanism of drug resistence. Correlation could not be established between electric current production with either ROS and MMP without distinguishing the types of electric current.

Protein Kinase C (PKC) Isozymes and Cancer

Protein kinase C (PKC) is a family of phospholipid-dependent serine/threonine kinases, which can be further classified into three PKC isozymes subfamilies: conventional or classic, novel or nonclassic, and atypical. PKC isozymes are known to be involved in cell proliferation, survival, invasion, migration, apoptosis, angiogenesis, and drug resistance. Because of their key roles in cell signaling, PKC isozymes also have the potential to be promising therapeutic targets for several diseases, such as cardiovascular diseases, immune and inflammatory diseases, neurological diseases, metabolic disorders, and multiple types of cancer. This review primarily focuses on the activation, mechanism, and function of PKC isozymes during cancer development and progression.

Inhibition of matrix metalloproteinase-9 expression by docosahexaenoic acid mediated by heme oxygenase 1 in 12-O-tetradecanoylphorbol-13-acetate-induced MCF-7 human breast cancer cells

Matrix metalloproteinase-9 (MMP-9) plays a crucial role in tumor metastasis. Previous studies showed that polyunsaturated fatty acids exhibit an anti-cancer effect in various human carcinoma cells, but the effect of docosahexaenoic acid (DHA) and linoleic acid (LA) on metastasis of breast cancer cells is not fully clarified. We studied the anti-metastasis potential of DHA and LA in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MCF-7 cells. We found that TPA (100 ng/ml) induced MMP-9 enzyme activity both dose- and time-dependently, and 200 μM DHA and LA significantly inhibited MMP-9 mRNA and protein expression, enzyme activity, cell migration, and invasion. Treatment with PD98059 (10 μM), wortmannin (10 μM), and GF109203X (0.5 μM) decreased TPA-induced MMP-9 protein expression and enzyme activity. TPA-induced activation of ERK1, Akt, and PKCδ was attenuated by DHA, whereas LA attenuated only ERK1 activation. GF109203X also suppressed ERK1 activation. EMSA showed that DHA, LA, PD98059, and wortmannin decreased TPA-induced NF-κB and AP-1 DNA-binding activity. Furthermore, DHA rather than LA dose-dependently increased HO-1 expression. HO-1 siRNA alleviated the inhibition by DHA of TPA-induced MMP-9 protein expression and enzyme activity in MCF-7 cells, and HO-1 knockdown reversed the DHA inhibition of cell migration. These results suggest that DHA and LA have both similar and divergent signaling pathways in the suppression of TPA-induced MCF-7 metastasis.

RTVP-1 expression is regulated by SRF downstream of protein kinase C and contributes to the effect of SRF on glioma cell migration

Gliomas are characterized by increased infiltration into the surrounding normal brain tissue. We recently reported that RTVP-1 is highly expressed in gliomas and plays a role in the migration of these cells, however the regulation of RTVP-1 expression in these cells is not yet described. In this study we examined the role of PKC in the regulation of RTVP-1 expression and found that PMA and overexpression of PKCα and PKCε increased the expression of RTVP-1, whereas PKCδ exerted an opposite effect. Using the MatInspector software, we identified a SRF binding site on the RTVP-1 promoter. Chromatin immunoprecipitation (ChIP) assay revealed that SRF binds to the RTVP-1 promoter in U87 cells, and that this binding was significantly increased in response to serum addition. Moreover, silencing of SRF blocked the induction of RTVP-1 expression in response to serum. We found that overexpression of PKCα and PKCε increased the activity of the RTVP-1 promoter and the binding of SRF to the promoter. In contrast, overexpression of PKCδ blocked the increase in RTVP-1 expression in response to serum and the inhibitory effect of PKCδ was abrogated in cells expressing a SRFT160A mutant. SRF regulated the migration of glioma cells and its effect was partially mediated by RTVP-1. We conclude that RTVP-1 is a PKC-regulated gene and that this regulation is at least partly mediated by SRF. Moreover, RTVP-1 plays a role in the effect of SRF on glioma cell migration.

An in vitro based investigation of the cytotoxic effect of water extracts of the Chinese herbal remedy LD on cancer cells

BACKGROUND

Long Dan Xie Gan Wan (LD), a Chinese herbal remedy formulation, is traditionally used to treat a range of conditions, including gall bladder diseases, hepatitis, hyperthyroidism, migraines but it is not used for the management or treatment of cancer. However some of its herbal constituents, specifically Radix bupleuri, Radix scutellariae and Rhizoma alismatis have been shown to inhibit the growth of cancer cells. Thus, the aim of the study was to investigate the impact of LD on cancer cells in vitro.

METHODS

HL60 and HT29 cancer cell lines were exposed to water extracts of LD (1:10, 1:50, 1:100 and/or 1:1000 prepared from a 3 mg/30 ml stock) and for both cell lines growth, apoptotic induction, alterations in cell cycle characteristics and genotoxicity were investigated. The specificity of the action of LD on these cancer cell lines was also investigated by determining its effect on human peripheral blood lymphocytes. Preliminary chemical analysis was carried out to identify cytotoxic constituents of LD using HPLC and LCMS.

RESULTS

LD was significantly cytotoxic to, and induced apoptosis in, both cell lines. Apoptotic induction appeared to be cell cycle independent at all concentrations of LD used (1:10, 1:50 and 1:100) for the HL60 cell lines and at 1:10 for the HT29 cell line. At 1:50 and 1:100 apoptotic induction by LD appeared to be cell cycle dependent. LD caused significant genotoxic damage to both cell lines compared to their respective controls. The specificity study showed that LD exerted a moderate cytotoxic action against non-proliferating and proliferating blood lymphocytes but not apoptosis. Chemical analysis showed that a number of fractions were found to exert a significant growth inhibitory effect. However, the molecular weights of compounds within these fractions did not correspond to those from the herbal constituents of LD.

CONCLUSION

It is possible that LD may have some chemotherapeutic potential. However, further studies are required to determine its cytotoxic constituents.

Inhibitory effect of penta-acetyl geniposide on C6 glioma cells metastasis by inhibiting matrix metalloproteinase-2 expression involved in both the PI3K and ERK signaling pathways

Penta-acetyl geniposide [(Ac)(5)GP], an acetylated geniposide product from Gardenia fructus, has been known to have hepatoprotective properties and recent studies have revealed its anti-proliferative and apoptotic effect on C6 glioma cells. In this study, we first report the anti-metastastic effect of (Ac)(5)GP in the rat neuroblastoma line: C6 glioma cells. First (Ac)(5)GP exhibited an inhibitory effect on abilities of adhesion and motility by cell-matrix adhesion assay, wound healing assay and Boyden chamber assay. Second, the decreasing activity of matrix metalloproteinase-2 (MMP-2) was noted by gelatin zymography assay. Further analysis with semi-quantitative RT-PCR showed the mRNA levels of MMP-2 and membrane type I matrix metalloproteinase (MT1-MMP) were significantly reduced, while the tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) was elevated by (Ac)(5)GP treatment. Further (Ac)(5)GP also exerted an inhibitory effect on phosphoinositide 3-kinase (PI3K) protein expression, phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and inhibition of activation of transcription factor nuclear factor kappa B (NF-kappaB), c-Fos, c-Jun. These findings proved (Ac)(5)GP is highly likely to be a inhibiting cancer migration agent to be further developed in the future.

Penta-acetyl geniposide induce apoptosis in C6 glioma cells by modulating the activation of neutral sphingomyelinase-induced p75 nerve growth factor receptor and protein kinase Cdelta pathway

In our previous studies, we demonstrated the apoptotic cascades protein kinase C (PKC) delta/c-Jun NH2-terminal kinase (JNK)/Fas/caspases induced by penta-acetyl geniposide [(Ac)5GP]. However, the upstream signals mediating PKCdelta activation have not yet been clarified. Ceramide, mainly generated from the degradation of sphingomyelin, was hypothesized upstream above PKCdelta in (Ac)5GP-transduced apoptosis. Furthermore, nerve growth factor (NGF)/p75 is supposed to be involved because(Ac)5GP-induced apoptosis was demonstrated previously in glioma cells. In the present study, (Ac)5GP was shown to activate neutral sphingomyelinase (N-SMase) immediately, with its maximum at 15 min. The NGF and p75 enhanced by (Ac)5GP was inhibited when added with GW4869, the N-SMase inhibitor, indicating NGF/p75 as the downstream signals of N-SMase/ceramide. To investigate whether N-SMase is involved in (Ac)5GP-transduced apoptotic pathway, cells were treated with (Ac)5GP added with or without GW4869. It showed that N-SMase inhibition blocked FasL expression and caspase 3 activation. Likewise, p75 antagonist peptide attenuated the FasL/caspase 3 expression. The PKCdelta translocation induced by (Ac)5GP was also eliminated by GW4869 and p75 antagonist peptide. To further confirm whether N-SMase activation plays an important role in (Ac)5GP-induced apoptosis, cells were analyzed the apoptotic rate by 4', 6-diamidino-2-phenylindole (DAPI) staining. (Ac)5GP-induced apoptosis was reduced 40 and 80% by 10 and 20 microM GW4869, respectively. It indicated that N-SMase activation is pivotal in (Ac)5GP-mediated apoptosis. In conclusion, SMase and NGF/p75 are suggested to mediate upstream above PKCdelta, thus transducing FasL/caspase cascades in (Ac)5GP-induced apoptosis.

Genipin-induced apoptosis in hepatoma cells is mediated by reactive oxygen species/c-Jun NH2-terminal kinase-dependent activation of mitochondrial pathway

Genipin, the aglycone of geniposide, exhibits anti-inflammatory and anti-angiogenic activities. Here we demonstrate that genipin induces apoptotic cell death in FaO rat hepatoma cells and human hepatocarcinoma Hep3B cells, detected by morphological cellular changes, caspase activation and release of cytochrome c. During genipin-induced apoptosis, reactive oxygen species (ROS) level was elevated, and N-acetyl-l-cysteine (NAC) and glutathione (GSH) suppressed activation of caspase-3, -7 and -9. Stress-activated protein kinase/c-Jun NH2-terminal kinase 1/2(SAPK/JNK1/2) but neither MEK1/2 nor p38 MAPK was activated in genipin-treated hepatoma cells. SP600125, an SAPK/JNK1/2 inhibitor, markedly suppressed apoptotic cell death in the genipin-treated cells. The FaO cells stably transfected with a dominant-negative c-Jun, TAM67, was less susceptible to apoptotic cell death triggered by genipin. Diphenyleneiodonium (DPI), an inhibitor of NADPH oxidase, inhibited ROS generation, apoptotic cell death, caspase-3 activation and JNK activation. Consistently, the stable expression of Nox1-C, a C-terminal region of Nox1 unable to generate ROS, blocked the formation of TUNEL-positive apoptotic cells, and activation of caspase-3 and JNK in FaO cells treated with genipin. Our observations imply that genipin signaling to apoptosis of hepatoma cells is mediated via NADPH oxidase-dependent generation of ROS, which leads to downstream of JNK.

Apoptosis induced by penta-acetyl geniposide in C6 glioma cells is associated with JNK activation and Fas ligand induction

In our previous study, penta-acetyl geniposide ((AC)(5)GP) is suggested to induce tumor cell apoptosis through the specific activation of PKCdelta. However, the downstream signal pathway of PKCdelta has not yet been investigated. It was shown that JNK may play an important role in the regulation of apoptosis and could be a possible downstream signal of PKCdelta isoforms. In the present study, we investigate whether JNK is involved in (AC)(5)GP induced apoptosis. The result reveals that (AC)(5)GP induces JNK activation and c-Jun phosphorylation thus stimulating the expression of Fas-L and Fas. Using SP600125 to block JNK activation shows that (AC)(5)GP-mediated apoptosis and related proteins expression are attenuated. Furthermore, we find that the (AC)(5)GP induces apoptosis through the activation of JNK/Jun/Fas L/Fas/caspase 8/caspase 3, a mitochondria-independent pathway. The JNK pathway is suggested to be the downstream signal of PKCdelta, since rottlerin impedes (AC)(5)GP-induced JNK activation. Therefore, (AC)(5)GP mediates cell death via activation of PKCdelta/JNK/FasL cascade signaling.