Gambogic acid synergistically potentiates cisplatin-induced apoptosis in non-small-cell lung cancer through suppressing NF-κB and MAPK/HO-1 signalling

Synergistic cytotoxic effects of a combined treatment of a Pinellia pedatisecta lipid-soluble extract and cisplatin on human cervical carcinoma in vivo

Herbal medicines are known to have numerous benefits, including lower toxicity and fewer side effects than traditional chemotherapeutic drugs. In traditional Chinese medicine, the rhizome of Pinellia pedatisecta (PE) Schott has long been used to treat cancer, undiagnosed swelling and erythema toxicum. However, its medical benefits lack support from scientific evidence. A novel lipid-soluble extract from PE has been previously verified to enhance the cytotoxicity of cis-dichlorodiammineplatinum-II (CDDP) against human cervical cancer cells in vitro. The present study evaluated the synergistic cytotoxic effects of PE and CDDP against human cervical cancer. Combination therapy of PE with CDDP exhibited synergistic cytotoxicity towards CaSki cell growth in mouse xenograft tumors. PE exhibited a cytotoxic effect on tumor size and weight, although the inhibitory ratio of tumor weight was only 26.3% in the PE-treated group. However, when mice were co-treated with PE and CDDP, the inhibitory ratio was higher than that of mice treated with CDDP alone (50.8 vs. 68.4%, respectively). The potential synergistic mechanism was likely via inhibiting the signaling E6/p53 pathway, restoring p53 function and inducing downstream tumor suppressor chain effects on apoptosis. Western blot analysis and immunohistochemistry indicated thatE6protein expression was significantly decreased upon treatment with combined PE and CDDP. The expression of p53 was increased in the combined PE and CDDP treatment group. Upregulation of p53-dependent apoptosis-associated proteins, including Bcl-2-associated X protein and cleaved caspases-9 and −3, was observed in the combined PE and CDDP treatment group. Our results present a molecular basis for the future application of the combination of PE and CDDP in the treatment of cervical cancer as a novel and pharmacologically safe chemotherapeutic strategy.

Inhibition of Survival Pathways MAPK and NF-kB Triggers Apoptosis in Pancreatic Ductal Adenocarcinoma Cells via Suppression of Autophagy

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a survival rate of 4-6 months from diagnosis. PDAC is the fourth leading cause of cancer-related death in the Western world, with a mortality rate of 10 cases per 100,000 population. Chemotherapy constitutes only a palliative strategy, with limited effects on life expectancy.

AIMS

To investigate the biological response of PDAC to mitogen-activated protein kinase (MAPK) and NF-kappaB (NF-kB) inhibitors and the role of autophagy in the modulation of these signaling pathways in order to address the challenge of developing improved medical protocols for patients with PDAC.

METHODS

Two ATCC cell lines, MIAPaCa-2 and PANC-1, were used as PDAC models. Cells were exposed to inhibitors of MAPK or NF-kB survival pathways alone or after autophagy inhibition. Several aspects were analyzed, as follows: cell proliferation, by [(3)H]TdR incorporation; cell death, by TUNEL assay, regulation of autophagy by LC3-II expression level and modulation of pro-and anti-apoptotic proteins by Western blot.

RESULTS

We demonstrated that the inhibition of the MAPK and NF-kB survival pathways with U0126 and caffeic acid phenethyl ester (CAPE), respectively, produced strong inhibition of pancreatic tumor cell growth without inducing apoptotic death. Interestingly, U0126 and CAPE induced apoptosis after autophagy inhibition in a caspase-dependent manner in MIA PaCa-2 cells and in a caspase-independent manner in PANC-1 cells.

CONCLUSIONS

Here we present evidence that allows us to consider a combined therapy regimen comprising an autophagy inhibitor and a MAPK or NF-kB pathway inhibitor as a possible treatment strategy for pancreatic cancer.

Wogonin reversed resistant human myelogenous leukemia cells via inhibiting Nrf2 signaling by Stat3/NF-κB inactivation

Constitutive NF-E2-related factor 2 (Nrf2, NFE2L2) activation has been recently reported to play a pivotal role in enhancing cell survival and resistance to anticancer drugs in many tumors. Wogonin had strong reversal potency via reduction of Nrf2 mRNA in Adriamycin (ADR)-induced resistant human chronic myelogenous leukemia (CML) K562/A02, but the mechanism of reduction of Nrf2 mRNA was still unclear. In this study, we aimed to delineate the mechanism by which Wogonin suppressed transcription of Nrf2 in resistant CML cells and further evaluate the reversal effects of Wogonin on the established animal models. Data indicated that Wogonin suppressed transcription of Nrf2 by NF-κB inactivation. Wogonin inhibited the binding of p65 to Nrf2 by suppression of the κB-binding activity. Further research revealed the κB2 site was responsible for the decreased Nrf2 by Wogonin in resistant K562 cells. Furthermore, reduction of pY705-Stat3 was involved in inhibition of the binding of p65 to Nrf2 by Wogonin. In vivo, Wogonin potentiated the inhibitory effect of ADR on leukemia development by suppressing pY705-Stat3 and Nrf2 signaling. In summary, these results demonstrated Wogonin could combat chemoresistance effectively through inhibiting Nrf2 via Stat3/NF-κB signaling, and supported that Wogonin can be developed into an efficient natural sensitizer for resistant human myelogenous leukemia.

Titania-coated gold nanorods as an effective carrier for gambogic acid

Titania-coated gold nanorods were used as a carrier for gambogic acid, and the drug-loaded nanoparticles show an enhanced anticancer effect.

Inhibition of heme oxygenase-1 enhances the chemosensitivity of laryngeal squamous cell cancer Hep-2 cells to cisplatin

It has been previously reported that cisplatin is a well-known anticancer drug being used against a wide range of malignancies including head and neck, ovarian and non-small cell lung carcinoma, and demonstrated its anticancer activity by reacting with DNA or changing cell structure, immune response, reactive oxygen species level (ROS). In this research we proved that cisplatin induced cell injuries and heme oxygenase-1 (HO-1) expression in laryngeal squamous cell cancer Hep-2 cells through ROS generation. The induction of HO-1 clearly protected Hep-2 cells from cisplatin-induced cell death and ROS reaction, and the inhibitor of HO-1 enhanced the cell death and ROS generation induced by cisplatin. Furthermore, the HO-1 expression induced by cisplatin was strongly inhibited by the knockdown of nuclear factor-erythroid-2-related factor-2 (Nrf-2), and the oxidative damages induced by cisplatin were significantly enhanced. Therefore, it may be concluded that the inhibition of HO-1 or the knockdown of Nrf-2 significantly enhanced cisplatin's anticancer effects on Hep-2 cells. In clinic, with the overexpression of HO-1 in laryngeal squamous cancer tissues, the combination of cisplatin with the inhibitor of HO-1 or Nrf-2 siRNA may act as a new method to the treatment of laryngeal squamous cancer.

Role of gambogic acid and NaI131 in A549/DDP cells

Resistance to platinum in tumor tissue is a considerable barrier against effective lung cancer treatment. Radionuclide therapy is the primary adjuvant treatment, however, the toxic side effects limit its dosage in the clinical setting. Therefore, the present study aimed to determine whether an NaI¹³¹ radiosensitizer could help reduce the toxic side effects of radionuclide therapy. In vitro experiments were conducted to determine whether NaI¹³¹ can inhibit platinum resistance in A549/DDP cells, which are cisplatin-resistant non-small cell lung cancer cells, and whether gambogic acid (GA) is an effective NaI¹³¹ radiosensitizer. Cell proliferation following drug intervention was analyzed using MTT and isobolographic analysis. Apoptosis was assessed by flow cytometry. In addition, the mechanisms of drug intervention were analyzed by measuring the expression of P-glycoprotein (P-gP), B cell lymphoma 2 (Bcl-2), Bcl2-associated X protein (Bax) and P53 using western blot analysis and immunocytochemistry. According to isobolographic analysis, a low concentration of NaI¹³¹ combined with GA had a synergistic effect on the inhibition of A549/DDP cell proliferation, which was consistent with an increased rate of apoptosis. Furthermore, the overexpression of Bax, and the downregulation of P-gP, P53 and Bcl-2 observed demonstrated the potential mechanism(s) of NaI¹³¹ and GA intervention. NaI¹³¹ may induce apoptosis in A549/DDP cells by regulating apoptosis-related proteins. A low concentration combination of NaI¹³¹ and GA was able to significantly inhibit A549/DDP cell proliferation and induce cell apoptosis. Thus, the two drugs appear to have a synergistic effect on apoptosis of A549/DDP cells.

Anti-tumor activity of SL4 against breast cancer cells: induction of G2/M arrest through modulation of the MAPK-dependent p21 signaling pathway

SL4, a chalcone-based compound, has been shown to retard tumor invasion and angiogenesis by suppressing HIF1 activity and to induce apoptosis by promoting ROS release. Here, we report that SL4 is able to inhibit the proliferation of different types of breast cancer cell in vitro and in vivo by inducing G₂/M cell cycle arrest. Our results showed that SL4 exhibited strong anti-proliferative activity in several human breast cancer cell lines, with IC₅₀ values lower than 1.3 μM. Further studies indicated that SL4 induced G₂/M arrest in these cell lines. Mechanistically, SL4 reduces the expression of cyclin A2 and cdc25C and decreases the activity of the cdc2/cyclin B1 complex. Notably, SL4 treatment resulted in an obvious increase in p21 mRNA and protein levels through activation of MAPK signaling pathways, but not the TGF-β pathway. SP600125 and PD98059, specific inhibitors of JNK kinase and ERK kinase, significantly blocked the SL4-induced G₂/M phase arrest and upregulation of p21. Furthermore, SL4 suppressed the growth of established breast tumors in nude mice through upregulation of p21 and downregulation of cdc25C, and displayed a good safety profile. Taken together, these findings demonstrate the potential value of SL4 as a novel multi-target anti-tumor drug candidate.

SYP-5, a novel HIF-1 inhibitor, suppresses tumor cells invasion and angiogenesis

Hypoxia-inducible factor-1 (HIF-1) plays an essential role in carcinogenesis. The overexpression of HIF-1 induced by hypoxia is closely associated with metastasis, poor prognosis and high mortality. In this study, a novel HIF-1 inhibitor SYP-5 was first observed by the luciferase reporter assay. Western blots results showed SYP-5 inhibited hypoxia-induced upregulation of HIF-1. Moreover, the proteins of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP)-2 that are targets of HIF-1, were down-regulated by SYP-5. Furthermore, in the tube formation assay, SYP-5 suppressed angiogenesis induced by hypoxia and VEGF in vitro. Additionally, using Transwell and RTCA assays, we found that SYP-5 also retarded the Hep3B and Bcap37 cells migration and invasion induced by hypoxia and FBS. Last, we also detected the upstream pathways related to HIF-1 and found both PI3K/AKT and MAPK/ERK were involved in the SYP-5 mediated invasive inhibition of Bcap37 cells. These results indicates that SYP-5 inhibits tumor cell migration and invasion, as well as tumor angiogenesis, which are mediated by suppressing PI3K/AKT- and MAPK/ERK-dependent HIF-1 pathway. It suggests that SYP-5 might be a potential HIF-1 inhibitor as an anticancer agent.

Hypoxia-induced resistance to cisplatin-mediated apoptosis in osteosarcoma cells is reversed by gambogic acid independently of HIF-1α

In vitro evidence of hypoxia-induced resistance to cisplatin (CDDP)-mediated apoptosis exists in human osteosarcoma (OS). Gambogic acid (GA) is a promising chemotherapeutic compound that could increase the chemotherapeutic effectiveness of CDDP in human OS cells by inducing cell cycle arrest and promoting apoptosis. This study examined whether GA could overcome OS cell resistance to CDDP. Hypoxia significantly reduced levels of CDDP-induced apoptosis in the OS cell lines MG63 and HOS. However, combined treatment with GA and CDDP revealed a strong synergistic action between these drugs, and higher protein levels of the apoptosis-related factor Fas, cleaved caspase-8 and cleaved caspase-3 and lower expression of hypoxia-inducible factor (HIF)-1α are detected in both cell lines. Meanwhile, drug resistance was not reversed by exposure to the HIF-1α inhibitor 2-methoxyestradiol. These findings strongly suggest that hypoxia-induced resistance to CDDP is reversed by GA in OS cells independently of HIF-1α. Furthermore, in vivo studies using xenograft mouse models revealed that combination therapy with CDDP and GA exerted increased antitumor effects by inducing apoptosis. Taken together, our results demonstrate that GA may be a new potent therapeutic agent useful for targeting human OS cells.

Lobaplatin for the treatment of SK-MES-1 lung squamous cell line in vitro and in vivo

Lung squamous cell carcinoma is the second-largest histological subtype of lung cancer, which is the leading cause of cancer-related death worldwide. Lobaplatin, one of the third-generation platinum compounds, has shown encouraging anticancer activity in a variety of tumors. The aim of this study was to determine the therapeutic efficacy of lobaplatin on p53-mutant lung squamous cancer cells SK-MES-1. In order to evaluate the antitumor effect of lobaplatin, several in vitro and in vivo analyses were carried out, including Cell Counting Kit-8 (CCK-8), fluorescence-activated cell sorter, Western blot, and terminal deoxynucleotidyl transferase dUTP nick end labeling. Findings showed that lobaplatin could inhibit cell proliferation and induce apoptosis of SK-MES-1 cells in vitro through both intrinsic and extrinsic apoptotic pathways in a time- and dose-dependent manner. In addition, lobaplatin could arrest cell cycle at S phase in SK-MES-1. Lobaplatin has obvious antitumor efficacy in human SK-MES-1 xenograft models; therefore, it seems to be a promising candidate in lung squamous cancer therapy.

Steroid receptor coactivator-3 is a pivotal target of gambogic acid in B-cell Non-Hodgkin lymphoma and an inducer of histone H3 deacetylation

Gambogic acid (GA), the active ingredient from gamboges, has been verified as a potent anti-tumor agent in many cancer cells. Nevertheless, its function in lymphoma, especially in B-cell Non-Hodgkin lymphoma (NHL), remains unclear. Amplification and/or overexpression of steroid receptor coactivator-3 (SRC-3) have been detected in multiple tumors and have confirmed its critical roles in carcinogenesis, progression, metastasis and therapy resistance in these cancers. However, no clinical data have revealed the overexpression of SRC-3 and its role in B-cell NHL. In this study, we demonstrated the anti-tumor effects of GA, which included cell growth inhibition, G1/S phase cell cycle arrest and apoptosis in B-cell NHL. We also verified that SRC-3 was overexpressed in B-cell NHL in both cell lines and lymph node samples from patients. The overexpressed SRC-3 was a central drug target of GA, and its down-regulation subsequently modulated down-stream gene expression, ultimately contributing to apoptosis. Silencing SRC-3 decreased the expression of Bcl-2, Bcl-6 and cyclin D3, but not of NF-κB and IκB-α. GA treatment did not inhibit the activation of AKT signaling pathway, but induced the deacetylation of histone H3 at lysine 9 and lysine 27. Down-regulated SRC-3 was observed to interact with more HDAC1 to mediate the deacetylation of H3. As the component of E3 ligase, Cullin3 was up-regulated and mediated the degradation of SRC-3. Our results demonstrate that GA is a potent anti-tumor agent that can be used for therapy against B-cell NHL, especially against those with an abundance of SRC-3.

Spontaneously-forming spheroids as an in vitro cancer cell model for anticancer drug screening

The limited translational value in clinic of analyses performed on 2-D cell cultures has prompted a shift toward the generation of 3-dimensional (3-D) multicellular systems. Here we present a spontaneously-forming in vitro cancer spheroid model, referred to as spheroids^MARY-X, that precisely reflects the pathophysiological features commonly found in tumor tissues and the lymphovascular embolus. In addition, we have developed a rapid, inexpensive means to evaluate response following drug treatment where spheroid dissolution indices from brightfield image analyses are used to construct dose-response curves resulting in relevant IC₅₀ values. Using the spheroids^MARY-X model, we demonstrate the unique ability of a new class of molecules, containing the caged Garcinia xanthone (CGX) motif, to induce spheroidal dissolution and apoptosis at IC₅₀ values of 0.42 +/−0.02 μM for gambogic acid and 0.66 +/−0.02 μM for MAD28. On the other hand, treatment of spheroids^MARY-X with various currently approved chemotherapeutics of solid and blood-borne cancer types failed to induce any response as indicated by high dissolution indices and subsequent poor IC₅₀ values, such as 7.8 +/−3.1 μM for paclitaxel. Our studies highlight the significance of the spheroids^MARY-X model in drug screening and underscore the potential of the CGX motif as a promising anticancer pharmacophore.

Combination of gambogic acid with cisplatin enhances the antitumor effects on cisplatin-resistant lung cancer cells by downregulating MRP2 and LRP expression

Cisplatin resistance is a main clinical problem of lung cancer therapy. Gambogic acid (GA) could prohibit the proliferation of a variety of human cancer cells. However, the effects of GA on cisplatin-resistant lung cancer are still unclear. The objective of the present study was to find out the antitumor effects of GA on cisplatin-resistant human lung cancer A549/DDP cells and further explore its underlying mechanisms. Cell Counting Kit-8 assay was used to observe the impacts of GA and/or cisplatin on the proliferation of lung cancer cells; flow cytometry was used to detect the effects of GA on cell cycle and apoptosis; Western blot was used to examine the effects of GA on the expression of lung resistance protein (LRP) and multidrug resistance-associated protein 2 (MRP2) protein in A549/DDP cells. Our results showed that GA dose- and time-dependently prohibited the proliferation and induced significant cell apoptosis in A549 and A549/DDP cells. GA also induced G0/G1 arrest in both A549/DDP and A549 cells. Moreover, GA upregulated protein expression level of cleaved caspase-3 and Bax and downregulated protein expression level of pro-caspase-9 and Bcl-2 in time- and dose-dependent way in A549/DDP cells. GA combined with cisplatin enhanced the cells apoptotic rate and reduced the cisplatin resistance index in A549/DDP cells. In addition, GA reduced the MRP2 and LRP protein expression level in A549/DDP cells. GA inhibits the proliferation, induces cell cycle arrest and apoptosis in A549/DDP cells. Combination of GA with cisplatin enhances the antitumor effects on cisplatin-resistant lung cancer cells by downregulating MRP2 and LRP expression.

The herbal extract KCHO-1 exerts a neuroprotective effect by ameliorating oxidative stress via heme oxygenase-1 upregulation

KCHO-1 is a novel product comprised of 30% ethanol extracts obtained from nine medical herbs, which are commonly used in traditional Korean and Chinese medicine. The nine herbs include Curcuma longa, Salvia miltiorrhiza, Gastrodia elata, Chaenomeles sinensis, Polygala tenuifolia, Paeonia japonica, Glycyrrhiza uralensis, Atractylodes japonica and processed Aconitum carmichaeli. Recent studies have reported the beneficial effects of these herbs. The present study aimed to investigate the direct neuroprotective effects of KCHO‑1 on HT22 mouse hippocampal cells, and to determine the possible underlying mechanisms. KCHO‑1 significantly suppressed glutamate‑ and hydrogen peroxide (H2O2)‑induced cell damage, and reactive oxygen species generation. In addition, KCHO‑1 increased the mRNA and protein expression levels of heme oxygenase (HO)‑1. Tin protoporphyrin, which is an inhibitor of HO activity, partially suppressed the effects of KCHO‑1. Furthermore, KCHO‑1 significantly upregulated nuclear factor erythroid‑derived 2‑related factor‑2 (Nrf2) nuclear translocation. Extracellular signal‑regulated kinase (ERK) activation also appeared to be associated with KCHO‑1‑induced HO‑1 expression, since the ERK inhibitor PD98059 suppressed HO‑1 expression and prevented KCHO‑1‑induced cytoprotection. The results of the present study suggested that KCHO‑1 may effectively prevent glutamate‑ or H2O2‑induced oxidative damage via Nrf2/ERK mitogen‑activated protein kinase‑dependent HO‑1 expression. These data suggest that KCHO‑1 may be useful for the treatment of neurodegenerative diseases.

Mangiferin enhances the sensitivity of human multiple myeloma cells to anticancer drugs through suppression of the nuclear factor κB pathway

Multiple myeloma (MM) is still an incurable hematological malignancy with a 5-year survival rate of ~35%, despite the use of various treatment options. The nuclear factor κB (NF-κB) pathway plays a crucial role in the pathogenesis of MM. Thus, inhibition of the NF-κB pathway is a potential target for the treatment of MM. In a previous study, we showed that mangiferin suppressed the nuclear translocation of NF-κB. However, the treatment of MM involves a combination of two or three drugs. In this study, we examined the effect of the combination of mangiferin and conventional anticancer drugs in an MM cell line. We showed that the combination of mangiferin and an anticancer drug decreased the viability of MM cell lines in comparison with each drug used separately. The decrease in the combination of mangiferin and an anticancer drug induced cell viability was attributed to increase the expression of p53 and Noxa and decreases the expression of XIAP, survivin, and Bcl-xL proteins via inhibition of NF-κB pathway. In addition, the combination treatment caused the induction of apoptosis, activation of caspase-3 and the accumulation of the cells in the sub-G1 phase of the cell cycle. Our findings suggest that the combination of mangiferin and an anticancer drug could be used as a new regime for the treatment of MM.

Novel cinnamohydroxamic acid derivatives as HDAC inhibitors with anticancer activity in vitro and in vivo

A novel series of cinnamohydroxamic acid derivatives were synthesized and their biological activities against HDAC were assessed. Our results showed that the compound with more strong inhibitory activity to HDAC would exhibited more significant anti-proliferative effect on tumor cells. Among these compounds, 7e displayed clearly inhibitory effects on HDAC and tumor cell growth. Furthermore, HDAC isoforms enzyme data indicated that, compared to HDAC pan-inhibitor SAHA, 7e owned an enhanced inhibitory effect on HDAC1, 3 and 6 isoforms. Meanwhile, it also significantly suppressed cell growth of lung cancer cells compared to SAHA, but with lower toxicity in normal cells. Mechanistically, 7e prompted acetylation of histone3 and histone4, led to up-regulation of p21, and then mediated cell cycle arrest and pro-apoptosis. Moreover, the in vivo study indicated that compound 7e could retard tumor growth of A549 xenograft models. These findings support the further investigation on the anti-tumor potential of this class of compounds as HDAC inhibitor.

Gambogic acid potentiates clopidogrel-induced apoptosis and attenuates irinotecan-induced apoptosis through down-regulating human carboxylesterase 1 and -2

1. In this study, we report that gambogic acid (GA), a promising anticancer agent, potentiates clopidogrel-induced apoptosis and attenuates CPT-11-induced apoptosis by down-regulating human carboxylesterase (CES) 1 and -2 via ERK and p38 MAPK pathway activation, which provides a molecular explanation linking the effect of drug combination directly to the decreased capacity of hydrolytic biotransformation. 2. The expression levels of CES1 and CES2 decreased significantly in a concentration- and time-dependent manner in response to GA in Huh7 and HepG2 cells; hydrolytic activity was also reduced. 3. The results showed that pretreatment with GA potentiated clopidogrel-induced apoptosis by down-regulating CES1. Moreover, the GA-mediated repression of CES2 attenuated CPT-11-induced apoptosis. 4. Furthermore, the ERK and p38 MAPK pathways were involved in the GA-mediated down-regulation of CES1 and CES2. 5. Taken together, our data suggest that GA is a potent repressor of CES1 and CES2 and that combination with GA will affect the metabolism of drugs containing ester bonds.

SL4, a chalcone-based compound, induces apoptosis in human cancer cells by activation of the ROS/MAPK signalling pathway

OBJECTIVES

SL4, a chalcone-based compound, exhibits clearly inhibitory effects on HIF-1 and has been shown to effectively suppress tumour invasion and angiogenesis in vitro and in vivo. Here, studies were conducted to determine SL4's anti-apoptotic effects and its underlying mechanisms, in human cancer cells.

MATERIALS AND METHODS

Cytotoxicity, apoptotic induction and its involved mechanisms of SL4 were investigated using normal cells, cancer cells and mouse xenograft models. The role of reactive oxygen species (ROS) and mitogen-activated protein kinase (MAPK) signalling in SL4-induced apoptosis was explored by manipulating specific scavenger or signalling inhibitors, in cultured cells.

RESULTS

SL4 significantly inhibited cell population growth of human cancer cell lines but exhibited lower cytotoxicity against normal cells. In addition, SL4 effectively induced apoptosis of Hep3B and MDA-MB-435 cells by activating procaspase-8, -9 and -3, and down-regulating expression levels of XIAP, but did not affect HIF-1 apoptosis-related targets, Survivin and Bcl-XL. Further study showed that SL4 also reduced mitochondrial membrane potential and promoted generation of ROS. ROS generation and apoptotic induction by SL4 were blocked by NAC, a scavenger of ROS, suggesting SL4-induced apoptosis via ROS accumulation. We also found that MAPKs, JNK and p38, but not ERK1/2, to be critical mediators in SL4-induced apoptosis. SP600125 and SB203580, specific inhibitors of JNK kinase and p38 kinase, significantly retarded apoptosis induced by SL4. Moreover, anti-oxidant NAC blocked activation of JNK and p38 induced by SL4, indicating that ROS may act as upstream signalling of JNK and p38 activation. It is noteworthy that animal studies revealed dramatic reduction (49%) in tumour volume after 11 days SL4 treatment.

CONCLUSIONS

These data demonstrate that SL4 induced apoptosis in human cancer cells through activation of the ROS/MAPK signalling pathway, suggesting that it may be a novel lead compound, as a cancer drug candidate, with polypharmacological characteristics.

The Nrf2/HO-1 Axis in Cancer Cell Growth and Chemoresistance

The transcription factor, nuclear factor erythroid 2 p45-related factor 2 (Nrf2), acts as a sensor of oxidative or electrophilic stresses and plays a pivotal role in redox homeostasis. Oxidative or electrophilic agents cause a conformational change in the Nrf2 inhibitory protein Keap1 inducing the nuclear translocation of the transcription factor which, through its binding to the antioxidant/electrophilic response element (ARE/EpRE), regulates the expression of antioxidant and detoxifying genes such as heme oxygenase 1 (HO-1). Nrf2 and HO-1 are frequently upregulated in different types of tumours and correlate with tumour progression, aggressiveness, resistance to therapy, and poor prognosis. This review focuses on the Nrf2/HO-1 stress response mechanism as a promising target for anticancer treatment which is able to overcome resistance to therapies.

Antitumor activity of gambogic acid on NCI-H1993 xenografts via MET signaling pathway downregulation

The present study aimed to investigate the anti-tumor mechanisms of gambogic acid (GA) on NCI-H1993 xenografts in vivo. Non-small cell lung carcinoma NCI-H1993 cells, which harbor a MET gene amplification, were subcutaneously injected into athymic nude mice. The mice were randomly assigned to treatment with 10, 20 or 30 mg/kg GA for 3 weeks. At the end of the efficacy study, all the mice were sacrificed and the tumor tissues were subjected to western blot analysis and immunohistochemical (IHC) staining. GA inhibited NCI-H1993 xenograft tumor growth in a dose-dependent manner. Western blot analysis demonstrated that expression of phosphorylated (p)-MET and its downstream signaling molecules p-AKT and p-ERK1/2 were significantly inhibited by GA. IHC analysis of Ki-67 expression demonstrated that GA treatment resulted in dose-dependent inhibition of tumor cell proliferation. GA exerted antitumor effects on NCI-H1993 xenografts in vivo by direct regulation of the MET signaling pathway. Theses antitumor effects were primarily a result of its anti-proliferation function.

Copper improves the anti-angiogenic activity of disulfiram through the EGFR/Src/VEGF pathway in gliomas

Disulfiram (DSF) possesses anticancer activity by inducing apoptosis in vitro and in vivo in a copper (Cu)-dependent manner. DSF also potently inhibits angiogenesis, but the effect of Cu on this anti-angiogenic activity is unknown. Here we show that DSF inhibits the proliferation, migration, invasion, adhesion and complex tube formation of human umbilical vascular endothelial cells (HUVECs). Aortic ring assays and Matrigel plug assays revealed that DSF significantly inhibited the formation of microvessels. Importantly, Cu improved the anti-angiogenic activity of DSF in all these assays, while copper alone had no effect. DSF/Cu treatment of U87 human glioblastoma cells resulted in suppression of VEGF secretion through the EGFR/c-Src/VEGF pathway. Reduction of EGFR phosphorylation disables recruitment of multiple Src homology 2 (SH2) domains, resulting in transcriptional down-regulation of VEGF. The role of EGFR/c-Src/VEGF pathway was further confirmed by using specific inhibitor, which significantly improved the anti-angiogenic activity of DSF/Cu. DSF/Cu also exerted increased anti-tumor effects on subcutaneous and intracerebral U87 xenograft models by reducing microvessel density (MVD) and VEGF expression. These results indicate that Cu improves the anti-angiogenic activity of DSF by targeting the EGFR/Src/VEGF signaling pathway, thus providing a rationale for the use of DSF/Cu rather than DSF alone as an angiogenesis inhibitor in clinical applications.

Subpathway Analysis based on Signaling-Pathway Impact Analysis of Signaling Pathway

Pathway analysis is a common approach to gain insight from biological experiments. Signaling-pathway impact analysis (SPIA) is one such method and combines both the classical enrichment analysis and the actual perturbation on a given pathway. Because this method focuses on a single pathway, its resolution generally is not very high because the differentially expressed genes may be enriched in a local region of the pathway. In the present work, to identify cancer-related pathways, we incorporated a recent subpathway analysis method into the SPIA method to form the “sub-SPIA method.” The original subpathway analysis uses the k-clique structure to define a subpathway. However, it is not sufficiently flexible to capture subpathways with complex structure and usually results in many overlapping subpathways. We therefore propose using the minimal-spanning-tree structure to find a subpathway. We apply this approach to colorectal cancer and lung cancer datasets, and our results show that sub-SPIA can identify many significant pathways associated with each specific cancer that other methods miss. Based on the entire pathway network in the Kyoto Encyclopedia of Genes and Genomes, we find that the pathways identified by sub-SPIA not only have the largest average degree, but also are more closely connected than those identified by other methods. This result suggests that the abnormality signal propagating through them might be responsible for the specific cancer or disease.

Gambogic acid induces apoptosis and inhibits colorectal tumor growth via mitochondrial pathways

AIM: To investigate the effect of gambogic acid (GA) on apoptosis in the HT-29 human colon cancer cell line.

METHODS: H-29 cells were used for in vitro experiments in this study. Relative cell viability was assessed using MTT assays. Cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling and Hoechst 33342 staining, and quantified by flow cytometry. Cellular ultrastructure was observed by transmission electron microscopy. Real-time PCR and Western blot analyses were used to evaluate gene and protein expression levels. For in vivo experiments, BALB/c nude mice received subcutaneous injections of HT-29 cells in the right armpit. When well-established xenografts were palpable with a tumor size of 75 mm³, mice were randomly assigned to a vehicle (negative) control, positive control or GA treatment group (n = 6 each). The animals in the treatment group received one of three dosages of GA (in saline; 5, 10 or 20 mg/kg) via the caudal vein twice weekly, whereas animals in the negative and positive control groups were given equal volumes of 0.9% saline or 10 mg/kg docetaxel, respectively, via the caudal vein once weekly.

RESULTS: The cell viability assay showed that GA inhibited proliferation of HT-29 cells in a dose- and time-dependent manner after treatment with GA (0.00, 0.31, 0.62, 1.25, 2.50, 5.00 or 10.00 μmol/L) for 24, 48 or 72 h. After 48 h, the percentage of apoptotic cells in cells treated with 0.00, 1.25, 2.50 and 5.00 μmol/L GA was 1.4% ± 0.3%, 9.8% ± 1.2%, 25.7% ± 3.3% and 49.3% ± 5.8%, respectively. Ultrastructural analysis of HT-29 cells treated for 48 h with 2.5μmol/L GA revealed apoptotic bodies and condensed and fragmented nuclei. Levels of caspase-8, -9 and -3 mRNAs were significantly increased after treatment with GA (1.25, 2.50 or 5.00 μmol/L) for 48 h (P < 0.05 for all). Protein levels of apoptosis-related factors Fas, FasL, FADD, cytochrome c, and Apaf-1 were increased in GA-treated cells, whereas levels of pro-caspase-8, -9 and -3 were significantly decreased (P < 0.05 for all). Furthermore, GA significantly and dose-dependently inhibited the growth of HT-29 tumors in a mouse xenograft model (P < 0.05).

CONCLUSION: GA inhibits HT-29 proliferation via induction of apoptosis. The anti-cancer effects are likely mediated by death receptor (extrinsic) and mitochondrial (intrinsic) pathways.

Synergistic anti-tumour effects of tetrandrine and chloroquine combination therapy in human cancer: a potential antagonistic role for p21

BACKGROUND AND PURPOSE

Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the Chinese medicinal herb Stephaniae tetrandrae, has a long history in Chinese clinical applications to treat diverse diseases. Tetrandrine induced apoptosis or, at low concentrations, autophagy of human hepatocellular carcinoma cells. Here we have tested the effects of inhibitors of autophagy such as chloroquine, on the response to low concentrations of tetrandrine in cancer cells.

EXPERIMENTAL APPROACH

Cultures of several cancer cell lines, including Huh7, U251, HCT116 and A549 cells, were exposed to tetrandrine, chloroquine or a combination of these compounds. Cell viability and content of reactive oxygen species (ROS) were measured and synergy assessed by calculation of the combination index. Western blot and RT-PCR assays were also used along with fluorescence microscopy and histochemical techniques.

KEY RESULTS

Combinations of tetrandrine and chloroquine were more cytotoxic than the same concentrations used separately and these effects showed synergy. Such effects involved increased ROS generation and were dependent on caspase-3 but independent of Akt activity. Blockade of tetrandrine-induced autophagy with 3-methyladenine or bafilomycin-A1 induced apoptosis in cancer cells. Lack of p21 protein (p21(-/-) HCT116 cells) increased sensitivity to the apoptotic effects of the combination of tetrandrine and chloroquine. In a tumour xenograft model in mice, combined treatment with tetrandrine and chloroquine induced ROS accumulation and cell apoptosis, and decreased tumour growth.

CONCLUSIONS AND IMPLICATIONS

The combinations of tetrandrine and chloroquine exhibited synergistic anti-tumour activity, in vitro and in vivo. Our results suggest a novel therapeutic strategy for tumour treatment.

Melatonin potentiates cisplatin-induced apoptosis and cell cycle arrest in human lung adenocarcinoma cells

OBJECTIVES

Melatonin produces anti-cancer effects via several mechanisms, including by induction of apoptosis. In this way, it has been shown to be of use, in combination with chemotherapeutic drugs, for cancer treatment. The study described here has evaluated effects of melatonin on cytotoxicity, apoptosis and cell cycle arrest induced with the chemotherapeutic agent cisplatin, in human lung adenocarcinoma cisplatin-sensitive cell line (SK-LU-1), which previously had only limit data.

MATERIALS AND METHODS

Cells of the SK-LU-1 line were treated with melatonin alone at 1-5 mM concentration or cisplatin alone 10-200 μM, for 48 h in culture. Cytotoxicity was measured by MTT reduction assay. Apoptosis induction was detected by annexin V/PI staining using flow cytometric analysis and DAPI nuclear staining. Change in mitochondrial membrane potential (ΔΨm) was quantified using DiOC6(3) reagent and activities of caspases-3/7 were also investigated. DNA fractions were measured using propidium iodide (PI) staining.

RESULTS

Melatonin or cisplatin alone had 50% (IC50 ) cytotoxicity at 5 mM or 34 μM concentrations respectively. Combination of 1 or 2 mM melatonin and cisplatin significantly augmented cytotoxicity of cisplatin by reducing its IC50 to 11 and 4 μM, respectively. Consistently, combined treatment increased population of apoptotic cells by elevating mitochondrial membrane depolarization, activating caspases-3/7 and inducing cell cycle arrest in the S phase, compared to treatment with cisplatin alone.

CONCLUSION

These data demonstrate that melatonin enhanced cisplatin-induced cytotoxicity and apoptosis in SK-LU-1 lung cancer cells. SK-LU-1 cell population growth inhibition was mediated by cell cycle arrest in the S phase. These findings suggest that melatonin has the potential to be used for NSCLC treatment in combination with a chemotherapeutic agent such as cisplatin.

Fine-tuning vitamin E-containing telodendrimers for efficient delivery of gambogic acid in colon cancer treatment

Certain natural products such as gambogic acid (GA) exhibit potent antitumor effects. Unfortunately, administration of these natural products is limited by their poor solubility in conventional pharmaceutical solvents. In this study, a series of telodendrimers, composed of linear polyethylene glycol (PEG)-blocking-dendritic oligomer of cholic acid (CA) and vitamin E (VE), have been designed with architectures optimized for efficient delivery of GA and other natural anticancer compounds. Two of the telodendrimers with segregated CA and VE domains self-assembled into stable cylindrical and/or spherical nanoparticles (NPs) after being loaded with GA as observed under transmission electron microscopy (TEM), which correlated with the dynamic light scattering (DLS) analysis of sub-30 nm particle sizes. A very high GA loading capacity (3:10 drug/polymer w/w) and sustained drug release were achieved with the optimized telodendrimers. These novel nanoformulations of GA were found to exhibit similar in vitro cytotoxic activity against colon cancer cells as the free drug. Near-infrared fluorescence small animal imaging revealed preferential accumulation of GA-loaded NPs into tumor tissue. The optimized nanoformulation of GA achieved superior antitumor efficacy compared to GA-Cremophor EL formulation at equivalent doses in HT-29 human colon cancer xenograft mouse models. Given the mild adverse effects associated with this natural compound and the enhanced anticancer effects via tumor targeted telodendrimer delivery, the optimized GA nanoformulation is a promising alternative to the traditional chemotherapy in colon cancer treatment.

Gambogic acid suppresses cytochrome P450 3A4 by downregulating pregnane X receptor and up-regulating DEC1 in human hepatoma HepG2 cells

Gambogic acid suppresses cytochrome P450 3A4 by downregulating pregnane X receptor and up-regulating DEC1 in human hepatoma HepG2 cells.

PARP inhibitor, olaparib ameliorates acute lung and kidney injury upon intratracheal administration of LPS in mice

We have previously shown that PARP-1 inhibition provides protection against lung inflammation in the context of asthma and acute lung injury. Olaparib is a potent new generation PARP inhibitor that has been approved for human testing. The present work was designed to evaluate its beneficial potential against LPS-induced acute lung injury and acute kidney injury upon intratracheal administration of the endotoxin in mice. Administration of olaparib at different doses, 30 min after LPS treatment showed that single intraperitoneal injection of the drug at 5 mg/kg b.wt. reduced the total number of inflammatory cells particularly neutrophils in the lungs. This was associated with reduced pulmonary edema as the total protein content in the bronchoalveolar fluid was found to be decreased substantially. Olaparib provided strong protection against LPS-mediated secondary kidney injury as reflected by restoration of serum levels of urea, creatinine, and uric acid toward normal. The drug restored the LPS-mediated redox imbalance toward normal in lung and kidney tissues as assessed by measuring malondialdehyde and GSH levels. Finally, RT-PCR data revealed that olaparib downregulates the LPS-induced expression of NF-κB-dependent genes namely TNF-α, IL-1β, and VCAM-1 in the lungs without altering the expression of total p65NF-κB. Overall, the data suggest that olaparib has a strong potential to protect against LPS-induced lung injury and associated dysfunctioning of kidney in mice. Given the fact that olaparib is approved by FDA for human testing, our findings can pave the way for testing of the drug on humans inflicted with acute lung injury.

Telodendrimer nanocarrier for co-delivery of paclitaxel and cisplatin: A synergistic combination nanotherapy for ovarian cancer treatment

Cisplatin (CDDP) and paclitaxel (PTX) are two established chemotherapeutic drugs used in combination for the treatment of many cancers, including ovarian cancer. We have recently developed a three-layered linear-dendritic telodendrimer micelles (TM) by introducing carboxylic acid groups in the adjacent layer via "thio-ene" click chemistry for CDDP complexation and conjugating cholic acids via peptide chemistry in the interior layer of telodendrimer for PTX encapsulation. We hypothesize that the co-delivery of low dosage PTX with CDDP could act synergistically to increase the treatment efficacy and reduce their toxic side effects. This design allowed us to co-deliver PTX and CDDP at various drug ratios to ovarian cancer cells. The in vitro cellular assays revealed strongest synergism in anti-tumor effects when delivered at a 1:2 PTX/CDDP loading ratio. Using the SKOV-3 ovarian cancer xenograft mouse model, we demonstrate that our co-encapsulation approach resulted in an efficient tumor-targeted drug delivery, decreased cytotoxic effects and stronger anti-tumor effect, when compared with free drug combination or the single loading TM formulations.

Increase of IFN-γ and TNF-α production in CD107a + NK-92 cells co-cultured with cervical cancer cell lines pre-treated with the HO-1 inhibitor

Background

Natural killer (NK) cells eliminate virus-infected and tumor cells through the release of perforins and granzymes; they also produce Interferon gamma (IFN-γ) and Tumor necrosis factor alpha (TNF-α), which induce apoptosis in target cells. Many tumors express Heme oxygenase 1 (HO-1), and this expression has been associated with avoiding immunosuppression and apoptosis. In this work, HO-1+ Cervical cancer cell (CCC) lines were pre-treated with HO-1 inhibitor and we assessed whether this inhibition enhanced the sensitivity of CCC to NK cell activity.

Methods

We assessed the expression of HO-1 in HeLa, SiHa, and C-33A CCC by Flow cytometry (FC). CCC were pre-treated with SnPP or ZnPP HO-1 inhibitors. After that, NK-92 cells were co-cultured with HeLa, SiHa, and C-33A CCC pre-treated or not with HO-1 inhibitors, and the expression of IFN-γ, TNF-α, CD107a, Granzyme B, NKp44, NKp46, NKp30, and NKG2D was evaluated by FC.

Results

CCC lines HeLa, SiHa, and C-33A expressed HO-1. Inhibition of HO-1 in these cells increased the expression of IFN-γ and TNF-α in CD107a + NK-92 cells. We observed a reduction in the expression of NKG2D, NKp46, and NKp30 in NK cells co-cultured with HeLa and SiHa cells, and when HeLa and SiHa cells were pre-treated with the HO-1 inhibitors, the expression of NKG2D and NKp30 in NK cells was restored. We observed a similar effect in NK cells co-cultured with C-33A cells in NKp30 expression.

Conclusion

Inhibition of HO-1 in CCC induces an increase in IFN-γ and TNF-α production in CD107a + NK-92 cells and restores NKG2D, NKp46 and NKp30 downmodulation in NK cells.