Curcumin enhances the mitomycin C-induced cytotoxicity via downregulation of MKK1/2–ERK1/2-mediated Rad51 expression in non-small cell lung cancer cells

Curcumin and Its Analogs in Non-Small Cell Lung Cancer Treatment: Challenges and Expectations

Researchers have made crucial advances in understanding the pathogenesis and therapeutics of non-small cell lung cancer (NSCLC), improving our understanding of lung tumor biology and progression. Although the survival of NSCLC patients has improved due to chemoradiotherapy, targeted therapy, and immunotherapy, overall NSCLC recovery and survival rates remain low. Thus, there is an urgent need for the continued development of novel NSCLC drugs or combination therapies with less toxicity. Although the anticancer effectiveness of curcumin (Cur) and some Cur analogs has been reported in many studies, the results of clinical trials have been inconsistent. Therefore, in this review, we collected the latest related reports about the anti-NSCLC mechanisms of Cur, its analogs, and Cur in combination with other chemotherapeutic agents via the Pubmed database (accessed on 18 June 2022). Furthermore, we speculated on the interplay of Cur and various molecular targets relevant to NSCLC with discovery studio and collected clinical trials of Cur against NSCLC to clarify the role of Cur and its analogs in NSCLC treatment. Despite their challenges, Cur/Cur analogs may serve as promising therapeutic agents or adjuvants for lung carcinoma treatment.

Curcumin Induces Apoptosis of Chemoresistant Lung Cancer Cells via ROS-Regulated p38 MAPK Phosphorylation

This study aimed to challenge chemoresistance by curcumin (CUR) with drug-selected human lung cancer A549 sublines that continuously proliferate in the present of docetaxel (DOC) and vincristine (VCR). Their sensitivities to CUR were measured by MTT assay and the particular intracellular reactive oxygen species (ROS) was detected by fluorescence activated cell sorting (FACS) analysis. Apoptosis was analyzed by Annexin V assay of the flow cytometry. Inhibitors and RNA interference were used to examine the signaling pathway regulated by the kinases. The obtained data demonstrated that CUR induces chemoresistant cell apoptosis by generating ROS and application of N-acetylcysteine (NAC) blocks ROS production, resulting in apoptosis suppression. Phosphorylation of extracellular regulated kinase (ERK), p38 MAPK, and eIF-2α were increased but c-Jun N-terminal kinase (JNK) did not increase when chemoresistant cells were treated with CUR. Downregulation of ERK and p38 MAPK phosphorylation by their inhibitors had no effect on CUR-induced apoptosis. Interestingly, the knockdown of p38 MAPK with shRNA significantly reduced CUR-induced apoptosis on the chemoresistant sublines. Phosphorylation of the eIF-2α protein was inhibited when p38 MAPK was knocked down in DOC-resistant A549 cells, but a high level of phosphorylated eIF-2α protein remained on the VCR-resistant A549 cells when p38 MAPK was knocked down. These data confirmed that CUR-augmented ROS potently induced apoptosis via upregulated p38 MAPK phosphorylation. Therefore, activated p38 MAPK is considered a pro-apoptotic signal for CUR-induced apoptosis of chemoresistant human lung cancer cells.

Nanoscale Formulations: Incorporating Curcumin into Combination Strategies for the Treatment of Lung Cancer

Lung cancer remains the most common cancer worldwide. Although significant advances in screening have been made and early diagnosis strategies and therapeutic regimens have been developed, the overall survival rate remains bleak. Curcumin is extracted from the rhizomes of turmeric and exhibits a wide range of biological activities. In lung cancer, evidence has shown that curcumin can markedly inhibit tumor growth, invasion and metastasis, overcome resistance to therapy, and even eliminate cancer stem cells (CSCs). Herein, the underlying molecular mechanisms of curcumin were summarized by distinct biological processes. To solve the limiting factors that curtail the clinical applications of curcumin, nanoformulations encapsulating curcumin were surveyed in detail. Nanoparticles, including liposomes, micelles, carbon nanotubes (CNTs), solid lipid nanoparticles (SLNs), nanosuspensions, and nanoemulsions, were explored as proper carriers of curcumin. Moreover, it was firmly verified that curcumin has the ability to sensitize lung cancer cells to chemotherapeutic drugs, such as cisplatin and docetaxel, and to various targeted therapies. Regarding the advantages and drawbacks of curcumin, we concluded that combination therapy based on nanoparticles would be the optimal approach to broaden the application of curcumin in the clinic in the near future.

Recent Advances in Curcumin Treated Non-Small Cell Lung Cancers: An Impetus of Pleiotropic Traits and Nanocarrier Aided Delive ry

Characterized by the abysmal 18% five year survival chances, non-small cell lung cancers (NSCLCs) claim more than half of their sufferers within the first year of being diagnosed. Advances in biomedical engineering and molecular characterization have reduced the NSCLC diagnosis via timid screening of altered gene expressions and impaired cellular responses. While targeted chemotherapy remains a major option for NSCLCs complications, delayed diagnosis, and concurrent multi-drug resistance remain potent hurdles in regaining normalcy, ultimately resulting in relapse. Curcumin administration presents a benign resolve herein, via simultaneous interception of distinctly expressed pathological markers through its pleiotropic attributes and enhanced tumor cell internalization of chemotherapeutic drugs. Studies on NSCLC cell lines and related xenograft models have revealed a consistent decline in tumor progression owing to enhanced chemotherapeutics cellular internalization via co-delivery with curcumin. This presents an optimum readiness for screening the corresponding effectiveness in clinical subjects. Curcumin is delivered to NSCLC cells either (i) alone, (ii) in stoichiometrically optimal combination with chemotherapeutic drugs, (iii) through nanocarriers, and (iv) nanocarrier co-delivered curcumin and chemotherapeutic drugs. Nanocarriers protect the encapsulated drug from accidental and non-specific spillage. A unanimous trait of all nanocarriers is their moderate drug-interactions, whereby native structural expressions are not tampered. With such insights, this article focuses on the implicit NSCLC curative mechanisms viz-a-viz, free curcumin, nanocarrier delivered curcumin, curcumin + chemotherapeutic drug and nanocarrier assisted curcumin + chemotherapeutic drug delivery.

Natural Compounds That Target DNA Repair Pathways and Their Therapeutic Potential to Counteract Cancer Cells

Resistance to current cancer treatments is an important problem that arises through various mechanisms, but one that stands out involves an overexpression of several factors associated with DNA repair. To counteract this type of resistance, different drugs have been developed to affect one or more DNA repair pathways, therefore, to test different compounds of natural origin that have been shown to induce cell death in cancer cells is paramount. Since natural compounds target components of the DNA repair pathways, they have been shown to promote cancer cells to be resensitized to current treatments. For this and other reasons, natural compounds have aroused great curiosity and several research projects are being developed around the world to establish combined treatments between them and radio or chemotherapy. In this work, we summarize the effects of different natural compounds on the DNA repair mechanisms of cancer cells and emphasize their possible application to re-sensitize these cells.

RENISUS Plants and Their Potential Antitumor Effects in Clinical Trials and Registered Patents

Cancer is a significant cause of morbidity and mortality. Scientific advances, coupled with potential flaws in current treatments, are driving research into the discovery of new bioactive molecules. This systematic review focused on scientific studies with clinical trials and patents registered on the National Relation of Medicinal Plants of Interest to the Unified Health System (RENISUS) plants (or derivative compounds) with antitumor potential. Studies with 19 different forms of cancer were found, the prostate being the organ with the highest research incidence and the species Glycine max, Curcuma longa, and Zingiber officinale, beside the phytochemicals curcumin and soy isoflavone were the most tested in clinical trials/patents.

Therapeutic potentials of curcumin in the treatment of non-small-cell lung carcinoma

Non-small-cell lung carcinoma (NSCLC) is one of the most lethal malignancies that include more than 80% of lung cancer cases worldwide. During the past decades, plants and plant-derived products have attracted great interest in the treatment of various human diseases. Curcumin, the turmeric isolated natural phenolic compound, has shown a promising chemo-preventive and anticancer agent. Numerous studies have shown that curcumin delays the initiation and progression of NSCLC by affecting a wide range of molecular targets and cell signalling pathways including NF-kB, Akt, MAPKS, BCL-2, ROS and microRNAs (miRNAs). However, the poor oral bioavailability and low chemical stability of curcumin remain as major challenges in the utilisation of this compound as a therapeutic agent. Different analogs of curcumin and new delivery systems (e.g., micelles, nanoparticles and liposomes) provided promising solutions to overcome these obstacles and improve curcumin pharmacokinetic profile. The present review focuses on current reported studies about anti-NSCLC effects of curcumin. NSCLC involved miRNAs whose expression is regulated by curcumin has also been discussed. Furthermore, recent researches on the use of curcumin analogs and delivery systems to enhance the curcumin benefits in NSCLC are also described.

Neferine inhibits MDA-MB-231 cells growth and metastasis by regulating miR-374a/FGFR-2

BACKGROUND

Neferine (NEF) is a major bisbenzylisoquinline alkaloid mainly exists in the seed embryo of Nelumbo nucifera (Gaertn.) that possesses anti-tumor effects. Our study designed to check the effect of NEF on breast cancer MDA-MB-231 cells and further explore the potential mechanism.

METHODS

MDA-MB-231 cells were administrated with various dosages of NEF for 24 h after which cell viability was measured. The effects of NEF on cell proliferation, apoptosis, migration and invasion were assessed by BrdU staining, flow cytometry assay and Transwell assay. Western blot was utilized to assess the accumulation of proteins related with proliferation, apoptosis, metastasis, PI3K/AKT and MEK/ERK pathways.

RESULTS

Viability was efficiently reduced by NEF in a dose-dependent manner. NEF (8 μM) significantly suppressed cell proliferation, migration and invasion but enhanced apoptosis in MDA-MB-213 cells. Interestingly, NEF suppressed miR-374a expression and miR-374a mediated the inhibitory effect of NEF. Moreover, miR-374a positively regulated FGFR-2 expression and FGFR-2 overexpression impeded the effect of NEF on MDA-MB-213 cells. FGFR-2 overexpression abolished the suppressive effect of NEF on PI3K/AKT and MEK/ERK pathways.

CONCLUSION

We found that NEF possessed the anti-growth and anti-metastasis effect on MDA-MB-231 cells through regulating miR-374a/FGFR-2, which might provide new insight for breast cancer management.

Lithium chloride attenuates mitomycin C induced necrotic cell death in MDA-MB-231 breast cancer cells via HMGB1 and Bax signaling

The clinical use of potent anticancer drug mitomycin C (MMC) has limited due to side effects and resistance of cancer cells. The aim of this study was to investigate whether lithium chloride (LiCl), as a mood stabilizer, can affect the sensitivity of MDA-MB-231 breast cancer cells to mitomycin C. The cells were exposed to various concentrations of mitomycin C alone and combined with LiCl and the viability determined by trypan blue and MTT assays. Proteins were analyzed by western blot and mRNA expression of HMGB1 MMP9 and Bcl-2 were analyzed by RT-PCR. Flow cytometry was used to determine the cell cycle arrest and percent of apoptotic and necrotic cells. Concentration of Bax assessed by ELISA. Exposure of the cells to mitomycin C revealed IC₅₀ value of 20 μM, whereas pretreatment of the cells with LiCl induced synergistic cytotoxicity and IC₅₀ value declined to 5 μM. LiCl combined with mitomycin C significantly down-regulated HMGB1, MMP9 and Bcl-2 gene expression but significantly increased the level of Bax protein. In addition, the content of HMGB1 in the nuclei decreased and pretreatment with LiCl reduced the content of HMGB1 release induced by MMC. LiCl increased mitomycin C-induced cell shrinkage and PARP fragmentation suggesting induction of apoptosis in these cells. LiCl prevented mitomycin C-induced necrosis and changed the cell death arrest at G2/M-phase. Taking all together, it is suggested that LiCl efficiently enhances mitomycin C-induced apoptosis and HMGB1, Bax and Bcl-2 expression may play a major role in this process, the findings that provide a new therapeutic strategy for LiCl in combination with mitomycin C.

(-)-Guaiol regulates RAD51 stability via autophagy to induce cell apoptosis in non-small cell lung cancer

(-)-Guaiol, generally known as an antibacterial compound, has been found in many medicinal plants. Its roles in tumor suppression are still under investigation. In the study, we mainly focused on exploring its applications in dealing with non-small cell lung cancer (NSCLC) and the underlying mechanisms. Here, we show that (-)-Guaiol significantly inhibits cell growth of NSCLC cells both in vitro and in vivo. Further high throughput analysis reveals that RAD51, a pivotal factor in homologous recombination repair, is a potential target for it. The following mechanism studies show that (-)-Guaiol is involved in cell autophagy to regulate the expression of RAD51, leading to double-strand breaks triggered cell apoptosis. Moreover, targeting RAD51, which is highly overexpressed in the lung adenocarcinoma tissues, can significantly increase the chemosensitivity of NSCLC cells to (-)-Guaiol both in vitro and in vivo. All in all, our studies provide an attractive insight in applying (-)-Guaiol into NSCLC treatments and further suggest that knockdown of oncogenic RAD51 will greatly enhance the chemosensitivity of patients with NSCLC.

Ginsenosides synergize with mitomycin C in combating human non-small cell lung cancer by repressing Rad51-mediated DNA repair

The use of ginseng extract as an adjuvant for cancer treatment has been reported in both animal models and clinical applications, but its molecular mechanisms have not been fully elucidated. Mitomycin C (MMC), an anticancer antibiotic used as a first- or second-line regimen in the treatment for non-small cell lung carcinoma (NSCLC), causes serious adverse reactions when used alone. Here, by using both in vitro and in vivo experiments, we provide evidence for an optimal therapy for NSCLC with total ginsenosides extract (TGS), which significantly enhanced the MMC-induced cytotoxicity against NSCLC A549 and PC-9 cells in vitro when used in combination with relatively low concentrations of MMC. A NSCLC xenograft mouse model was used to confirm the in vivo synergistic effects of the combination of TGS with MMC. Further investigation revealed that TGS could significantly reverse MMC-induced S-phase cell cycle arrest and inhibit Rad51-mediated DNA damage repair, which was evidenced by the inhibitory effects of TGS on the levels of phospho-MEK1/2, phospho-ERK1/2 and Rad51 protein and the translocation of Rad51 from the cytoplasm to the nucleus in response to MMC. In summary, our results demonstrate that TGS could effectively enhance the cytotoxicity of MMC against NSCLC cells in vitro and in vivo, thereby revealing a novel adjuvant anticancer mechanism of TGS. Combined treatment with TGS and MMC can significantly lower the required concentration of MMC and can further reduce the risk of side effects, suggesting a better treatment option for NSCLC patients.

Curcumin increases breast cancer cell sensitivity to cisplatin by decreasing FEN1 expression

Flap endonuclease 1 (FEN1) overexpression promotes breast cancer. We investigated the role of FEN1 in cisplatin resistance and the chemosensitizing effects of curcumin in breast cancer cells. We demonstrated that FEN1 overexpression promotes cisplatin resistance in breast cancer cells, and that FEN1 knockdown enhances cisplatin sensitivity. Curcumin down-regulated FEN1 expression in a dose-dependent manner. A combination of cisplatin and curcumin enhanced breast cancer cell sensitivity to cisplatin by down-regulating FEN1 expression in vitro and in vivo. Increased ERK phosphorylation contributed to cisplatin resistance and cisplatin-induced FEN1 overexpression in breast cancer cells. Inhibiting ERK phosphorylation stimulated the chemosensitizing effect of curcumin to cisplatin by targeting FEN1. These data reveal that FEN1 overexpression promotes cisplatin resistance, and suggest FEN1 could be a potential therapeutic target to relieve cisplatin resistance in breast cancer. We also demonstrated that curcumin sensitizes breast cancer cells to cisplatin through FEN1 down-regulation.

Akt1 Stimulates Homologous Recombination Repair of DNA Double-Strand Breaks in a Rad51-Dependent Manner

Akt1 is known to promote non-homologous end-joining (NHEJ)-mediated DNA double-strand break (DSB) repair by stimulation of DNA-PKcs. In the present study, we investigated the effect of Akt1 on homologous recombination (HR)-dependent repair of radiation-induced DSBs in non-small cell lung cancer (NSCLC) cells A549 and H460. Akt1-knockdown (Akt1-KD) significantly reduced Rad51 protein level, Rad51 foci formation and its colocalization with γH2AX foci after irradiation. Moreover, Akt1-KD decreased clonogenicity after treatment with Mitomycin C and HR repair, as tested by an HR-reporter assay. Double knockdown of Akt1 and Rad51 did not lead to a further decrease in HR compared to the single knockdown of Rad51. Consequently, Akt1-KD significantly increased the number of residual DSBs after irradiation partially independent of the kinase activity of DNA-PKcs. Likewise, the number of residual BRCA1 foci, indicating unsuccessful HR events, also significantly increased in the irradiated cells after Akt1-KD. Together, the results of the study indicate that Akt1 seems to be a regulatory component in the HR repair of DSBs in a Rad51-dependent manner. Thus, based on this novel role of Akt1 in HR and the previously described role of Akt1 in NHEJ, we propose that targeting Akt1 could be an effective approach to selectively improve the killing of tumor cells by DSB-inducing cytotoxic agents, such as ionizing radiation.

Dexamethasone suppresses the growth of human non-small cell lung cancer via inducing estrogen sulfotransferase and inactivating estrogen

AIM

Dexamethasone (DEX) is a widely used synthetic glucocorticoid, which has shown anti-cancer efficacy and anti-estrogenic activity. In this study we explored the possibility that DEX might be used as an endocrine therapeutic agent to treat human non-small cell lung cancer (NSCLC).

METHODS

The viability and proliferation of human NSCLC cell lines A549 and H1299 were assessed in vitro. Anti-tumor action was also evaluated in A549 xenograft nude mice treated with DEX (2 or 4 mg·kg(-1)·d(-1), ig) or the positive control tamoxifen (50 mg·kg(-1)·d(-1), ig) for 32 d. The expression of estrogen sulfotransferase (EST) in tumor cells and tissues was examined. The intratumoral estrogen levels and uterine estrogen responses were measured.

RESULTS

DEX displayed mild cytotoxicity to the NSCLC cells (IC50 >500 μmol/L) compared to tamoxifen (IC50 <50 μmol/L), but it was able to inhibit the cell proliferation at low micromolar ranges. Furthermore, DEX (0.1-10 μmol/L) dose-dependently up-regulated EST expression in the cells, and inhibited the cell migration in vitro. Triclosan, a sulfation inhibitor, was able to diminish DEX-caused inhibition on the cell viability. In A549 xenograft nude mice, DEX or tamoxifen administration remarkably suppressed the tumor growth. Moreover, DEX administration dose-dependently increased EST expression in tumor tissues, and reduced intratumoral estrogen levels as well as the volumes and weights of uterine.

CONCLUSION

DEX suppresses the growth of A549 xenograft tumors via inducing EST and decreasing estradiol levels in tumor tissues, suggesting that DEX may be used as anti-estrogenic agent for the treatment of NSCLC.

Curcumin-Mediated HDAC Inhibition Suppresses the DNA Damage Response and Contributes to Increased DNA Damage Sensitivity

Chemo- and radiotherapy cause multiple forms of DNA damage and lead to the death of cancer cells. Inhibitors of the DNA damage response are candidate drugs for use in combination therapies to increase the efficacy of such treatments. In this study, we show that curcumin, a plant polyphenol, sensitizes budding yeast to DNA damage by counteracting the DNA damage response. Following DNA damage, the Mec1-dependent DNA damage checkpoint is inactivated and Rad52 recombinase is degraded by curcumin, which results in deficiencies in double-stand break repair. Additive effects on damage-induced apoptosis and the inhibition of damage-induced autophagy by curcumin were observed. Moreover, rpd3 mutants were found to mimic the curcumin-induced suppression of the DNA damage response. In contrast, hat1 mutants were resistant to DNA damage, and Rad52 degradation was impaired following curcumin treatment. These results indicate that the histone deacetylase inhibitor activity of curcumin is critical to DSB repair and DNA damage sensitivity.

Downregulation of Rad51 participates in OTA-induced DNA double-strand breaks in GES-1 cells in vitro

Ochratoxin A (OTA), a mycotoxin produced by ubiquitous Aspergilli, is carcinogenic, teratogenic, and nephrotoxic in both humans and animals. Our previous study found that OTA induced DNA double-strand breaks (DSBs) and resulted in G2 phase arrest in human gastric epithelium immortalized (GES-1) cells. DSBs can cause genomic instability, mutations, and neoplastic transformations, and improper repair of DSBs may lead to the development of cancer. Rad51 is a key protein in the homologous recombination (HR) pathway of DSBs repair. The roles of Rad51 in the repair of DNA damage vary in response to different types of cytotoxic agents. The effect of OTA on Rad51 expression and its putative role in the OTA-induced DSBs in GES-1 cells are still not clear enough. The aim of the current study is to elucidate the role of Rad51 in OTA-induced DSBs in GES-1 cells. The results showed that OTA treatment decreased Rad51 expression in a dose- and time-dependent manner. Specific downregulation of Rad51 by siRNA induced DSBs and G2 phase arrest. Rad51 overexpression by transfection with a Rad51-expressing plasmid partly rescued the DSBs and G2 phase arrest in OTA-treated cells. The findings indicate that downregulation of Rad51 contributes to OTA-induced DNA damage in GES-1 cells. Knockdown of p53 with siRNA for 48h effectively reversed the downregulation of Rad51, and decreased the OTA-induced DSBs in GES-1 cells. In addition, the downregulation of Rad51 induced by OTA could be significantly attenuated with specific ERK inhibitor PD98059 or specific p38 MAPK inhibitor SB203580 pre-treatment in GES-1 cells. Thus, the results suggest that downregulation of Rad51 participates in OTA-induced DNA double-strand breaks in GES-1 cells in vitro. And p53, ERK and p38 signaling pathways are all involved in the process.

Neferine, an alkaloid from lotus seed embryo, inhibits human lung cancer cell growth by MAPK activation and cell cycle arrest

Neferine is the major bisbenzylisoquinoline alkaloid isolated from the seed embryo of a traditional medicinal plant Nelumbo nucifera (Lotus). Epidemiological studies have revealed the therapeutic potential of lotus seed embryo. Although several mechanisms have been proposed, a clear anticancer action mechanism of neferine on lung cancer cells is still not known. Lung cancer is the most common cause of cancer death in the world, and the patients with advanced stage of nonsmall lung cancer require adjunct chemotherapy after surgical resection for the eradication of cancer cells. In this study, the effects of neferine were evaluated and characterized in A549 cells. Neferine induced apoptosis in a dose-dependent manner with the hypergeneration of reactive oxygen species, activation of MAPKs, lipid peroxidation, depletion of cellular antioxidant pool, loss of mitochondrial membrane potential, and intracellular calcium accumulation. Furthermore, neferine treatment leads to the inhibition of nuclear factor kappaB and Bcl2, upregulation of Bax and Bad, release of cytochrome C, activation of caspase cascade, and DNA fragmentation. In addition, neferine could induce p53 and its effector protein p21 and downregulation of cell cycle regulatory protein cyclin D1 thereby inducing G1 cell cycle arrest. These results suggest a novel function of neferine as an apoptosis inducer in lung cancer cells.

Inhibition of Raf-MEK-ERK and hypoxia pathways by Phyllanthus prevents metastasis in human lung (A549) cancer cell line

BACKGROUND

Lung cancer constitutes one of the malignancies with the greatest incidence and mortality rates with 1.6 million new cases and 1.4 million deaths each year. Prognosis remains poor due to deleterious development of multidrug resistance resulting in less than 15% lung cancer patients reaching five years survival. We have previously shown that Phyllanthus induced apoptosis in conjunction with its antimetastastic action. In the current study, we aimed to determine the signaling pathways utilized by Phyllanthus to exert its antimetastatic activities.

METHODS

Cancer 10-pathway reporter array was performed to screen the pathways affected by Phyllanthus in lung carcinoma cell line (A549) to exert its antimetastatic effects. Results from this array were then confirmed with western blotting, cell cycle analysis, zymography technique, and cell based ELISA assay for human total iNOS. Two-dimensional gel electrophoresis was subsequently carried out to study the differential protein expressions in A549 after treatment with Phyllanthus.

RESULTS

Phyllanthus was observed to cause antimetastatic activities by inhibiting ERK1/2 pathway via suppression of Raf protein. Inhibition of this pathway resulted in the suppression of MMP2, MMP7, and MMP9 expression to stop A549 metastasis. Phyllanthus also inhibits hypoxia pathway via inhibition of HIF-1α that led to reduced VEGF and iNOS expressions. Proteomic analysis revealed a number of proteins downregulated by Phyllanthus that were involved in metastatic processes, including invasion and mobility proteins (cytoskeletal proteins), transcriptional proteins (proliferating cell nuclear antigen; zinc finger protein), antiapoptotic protein (Bcl2) and various glycolytic enzymes. Among the four Phyllanthus species tested, P. urinaria showed the greatest antimetastatic activity.

CONCLUSIONS

Phyllanthus inhibits A549 metastasis by suppressing ERK1/2 and hypoxia pathways that led to suppression of various critical proteins for A549 invasion and migration.

Encapsulation of curcumin within poly(amidoamine) dendrimers for delivery to cancer cells

Curcumin has anti-proliferative and pro-apototic properties against a variety of cancer cells in vitro. Unfortunately, the water-insolubility and instability leads to its low bioavailability in vivo tests. Here, we report a general approach to using poly(amidoamine) dendrimer with acetyl terminal groups to encapsulate curcumin(G₅-Ac/Cur) for drug delivery to cancer cells. The solubility, release kinetics, anticancer activity, and apoptotic-related protein expression (Bax and Bcl-2) were investigated in detail. Comparing with curcumin, the water-solubility value of G₅-Ac/Cur increased 200-fold, and the release of curcumin from the complexes was in a sustained manner. G₅-Ac/Cur showed higher anti-proliferative activity against A549 cell lines and had the better effect on the generation of intracellular reactive oxygen species, the mitochondrial membrane potential and cell apoptosis. Furthermore, the ratio of Bax/Bcl-2 was higher in samples treated with G₅-Ac/Cur. The results indicated that the G₅-Ac drug delivery system could improve the solubility and anti-cancer effect of curcumin.

Assessing dose-dependent differences in DNA-damage, p53 response and genotoxicity for quercetin and curcumin

As part of a longer-term goal to create a quantitative mechanistic model of the p53-Mdm2 DNA-damage pathway, we are studying cellular responses to compounds causing DNA-damage by various modes-of action, including two natural polyphenols: quercetin (QUE) and curcumin (CUR). QUE and CUR are weak mutagens in some in vitro assays and possess both anti- or pro-oxidant effects depending on dose. This study examines the dose-response of DNA-damage pathway to these compounds in HT1080 cells (a human cell line with wild-type p53) at doses relevant to human exposure. CUR was more potent in causing reactive oxygen species, DNA damage (measured as phospho-H2AX) and p53 induction, with lowest observed effect levels (LOELs; 3-8 μM) approximately three-fold lower than QUE (20-30 μM). CUR showed a strong G2/M arrest and apoptosis at ≈ 10 μM. QUE caused S phase arrest at low doses (8 μM) and apoptosis was only induced at much higher doses (60 μM). At concentrations with similar levels of p-H2AX and p53 biomarkers, CUR caused greater micronuclei frequency. CUR induced clear increases micronuclei at 3-6 μM, while QUE had a weaker micronuclei response even at the highest doses. Thus, even with two compounds sharing common chemistries, DNA-damage response patterns differed significantly in terms of dose and cell fate.

Histology as a potential clinical predictor of outcome in advanced non-small-cell lung cancer treated with vinorelbine and mitomycin combination chemotherapy

BACKGROUND

The importance of clinical predictors in the treatment of non-small-cell lung cancer (NSCLC) has increased during the last decade. This retrospective study analyzed the combined patient-level data from two phase II trials that investigated the efficacy and safety of combination chemotherapy with vinorelbine and mitomycin in patients with locally advanced or metastatic NSCLC. The aim of this analysis was to determine if patients' baseline and disease characteristics, including histology, gender, smoking history, and expression of TTF-1, might be potential predictors of outcome.

METHODS

Response rates, unadjusted survival times, and Cox covariate-adjusted hazard ratios (HRs) were calculated. Results were reported separately for each subgroup in each individual trial and in the pooled data set.

RESULTS

A total of 175 patients were included in this analysis. Adjusted HRs for both overall survival (OS) and progression free survival (PFS) favored the nonadenocarcinoma histology subgroup, achieving a statistical significance for OS in the pooled data (n = 175; HR 0.68; 95 % CI 0.49-0.94; p = 0.019). TTF-1-negative immunohistochemistry was associated with a significantly higher response rate (25 vs. 0 %; p = 0.04) and with a nonsignificant advantage in OS (n = 33; HR 1.23; 95 % CI 0.56-2.73; p = 0.608). Gender and smoking history were not strongly related to outcome.

CONCLUSIONS

The results of this analysis indicate that patients with nonadenocarcinoma histology might get superior benefit from combination chemotherapy with vinorelbine and mitomycin. These results should be confirmed in a prospective study.

Terpecurcumins A-I from the rhizomes of Curcuma longa: absolute configuration and cytotoxic activity

Terpecurcumins A-I (1-9), together with three known analogues (10-12), were isolated from the rhizomes of Curcuma longa (turmeric). They were derived from the hybridization of curcuminoids and bisabolanes. The structures and absolute configurations of 1-9 were elucidated on the basis of extensive spectroscopic data analysis, including NMR and electronic circular dichroism spectra. The configuration of 10 was further confirmed by X-ray crystallography. A plausible biogenetic relationship for 1-12 is proposed. Compounds 4, 6, 7, 10, and 11 showed higher cytotoxic activities (IC(50), 10.3-19.4 μM) than curcumin (IC(50), 31.3-49.2 μM) against human cancer cell lines (A549, HepG2, and MDA-MB-231).

Curcumin regulates airway epithelial cell cytokine responses to the pollutant cadmium

Cadmium is a toxic metal present in the environment and its inhalation can lead to pulmonary disease such as lung cancer and chronic obstructive pulmonary disease. These lung diseases are characterized by chronic inflammation. Here we show that exposure of human airway epithelial cells to cadmium promotes a polarized apical secretion of IL-6 and IL-8, two pivotal pro-inflammatory cytokines known to play an important role in pulmonary inflammation. We also determined that two distinct pathways controlled secretion of these proinflammatory cytokines by human airway epithelial cells as cadmium-induced IL-6 secretion occurs via an NF-κB dependent pathway, whereas IL-8 secretion involves the Erk1/2 signaling pathway. Interestingly, the natural antioxidant curcumin could prevent both cadmium-induced IL-6 and IL-8 secretion by human airway epithelial cells. In conclusion, curcumin could be used to prevent airway inflammation due to cadmium inhalation.