Pentoxifylline sensitizes human cervical tumor cells to cisplatin-induced apoptosis by suppressing NF-kappa B and decreased cell senescence

Retinoblastoma: Review and new insights

Retinoblastoma (Rb), the most frequent malignant intraocular tumor in childhood, is caused by mutations in the retinoblastoma gene (RB1) situated on chromosome 13q14.2. The incidence of retinoblastoma is approximately 1 in 17,000 live births with approximately 8,000 new cases diagnosed each year worldwide. Rb is the prototypical hereditary cancer in humans. Autosomal dominant inheritance is seen in 30-40% of cases whereas the non-inherited sporadic type accounts for the remaining 60-70%. Rb arises due to inactivation of both alleles of the Rb tumor suppressor gene, which results in a defective Rb protein (pRB) with subsequent cell cycle impairment and uncontrolled cell proliferation. Patients with Rb have survival rates higher than 95-98% in industrialized countries but mortality remains high in developing countries. For example, the mortality rate in Africa is 70%. In all cases of intraocular and extraocular retinoblastoma, there is a need for new therapies that are more effective and carry less risk of toxicity. The Bruckner test is a practical and easy test for the detection of Rb, this test consists of assessing the fundus reflex through the pupil (red reflex) in both eyes simultaneously with a bright coaxial light produced with the direct ophthalmoscope. Rb can be detected by the Bruckner test showing a pupil that shines white or “Leukocoria”. Although the diagnosis of Rb remains essentially clinical, the newly identified biomarkers could contribute to early molecular detection, timely detection of micrometastases and establish new therapeutic options for Rb.

Pentoxifylline Inhibits Pulmonary Fibrosis by Regulating Cellular Senescence in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease, and its occurrence and development are mediated by cellular senescence. Drugs targeting senescent cells seem like a promising and efficacious strategy for IPF treatment. Previous studies have illustrated that pentoxifylline (PTX) may play a certain role in inhibiting pulmonary fibrosis and combating cellular senescence. In this study, we demonstrated that PTX administration inhibits pulmonary fibrosis development and cellular senescence in the bleomycin (BLM)-induced IPF mice model. Moreover, the expression levels of fibrosis-related genes and senescence-related genes in mice lung tissue and primary pulmonary fibroblasts illustrated lung fibroblasts' vital role in these two processes. And the curative effect of PTX was completed mainly by acting on lung fibroblasts. Besides, during the whole treatment, delayed initiation or advanced halt of PTX administration would influence its effectiveness in reducing fibrotic and senescent traits in various degrees, and the latter influenced more. We further determined that a long period of PTX administration could bring noticeable benefits to mice in recovering BLM-induced lung fibrosis and suppressing age-associated cellular senescence. Moreover, it was still effective when PTX administration was used to treat senescent human fibroblasts. Thus, our findings manifested that PTX therapy is an efficient remedy for pulmonary fibrosis by suppressing cellular senescence.

Lappaconitine hydrochloride inhibits proliferation and induces apoptosis in human colon cancer HCT-116 cells via mitochondrial and MAPK pathway

Lappaconitine hydrochloride (LH), as a new synthetic alkaloid, exhibits antitumor activity, whereas its antitumor effect on colorectal cancer (CRC) has not been investigated. In this study, the effect of LH on HCT-116 cell proliferation and apoptosis in vivo and in vitro and underlying molecular mechanism were explored. The Cell Counting Kit-8 (CCK-8) was used to assess cell viability. Morphological change was observed by Hoechst 33342 staining. Cell cycle and apoptosis were performed using a flow cytometer. The western blot method was used to screen for related protein expression. The mitochondrial membrane potential (MMP) was confirmed using the 5, 5, 6, 6'-tetrachloro-1, 1', 3, 3'-tetraethylbenzimi-dazolyl carbo cyanine iodide (JC-1) staining assay. Reactive oxygen species (ROS) was evaluated by a 20-70-dichlorofluorescein diacetate (DCFH-DA) staining assay. The antitumor effect was evaluated in vivo by the xenograft HCT-116 model. The results showed that LH significantly inhibited cell viability in a time- and concentration-dependent manner. LH induced apoptosis and S phase cell cycle arrest. LH promoted the reduction of MMP and ROS accumulation. Moreover, LH activated the mitochondrial and MAPK pathway. The experiments in vivo showed that LH had significant antitumor effect in tumor-bearing mice, and had virtually no effect on the weight and internal organs of the mice. In conclusion, LH could induce apoptosis in HCT-116 cells through mitochondrial and MAPK signaling pathways. LH may be a promising treatment for CRC.

Sensitizing the cytotoxic action of Docetaxel induced by Pentoxifylline in a PC3 prostate cancer cell line

BACKGROUND

Prostate cancer is one of the most frequently diagnosed types of cancers worldwide. In its initial period, the tumor is hormone-sensitive, but in advanced states, it evolves into a metastatic castration-resistant tumor. In this state, chemotherapy with taxanes such as Docetaxel (DTX) comprises the first line of treatment. However, the response is poor due to chemoresistance and toxicity. On the other hand, Pentoxifylline (PTX) is an unspecific inhibitor of phosphodiesterases; experimental, and clinically it has been described as sensitizing tumor cells to chemotherapy, increasing apoptosis and decreasing senescence. We study whether the PTX sensitizes prostate cancer cells to DTX for greater effectiveness.

METHODS

PC3 human prostate cancer cells were treated in vitro at different doses and times with PTX, DTX, or their combination. Viability was determined by the WST-1 assay by spectrophotometry, cell cycle progression, apoptosis, generic caspase activation and senescence by flow cytometry, DNA fragmentation and caspases-3, -8, and -9 activity by ELISA.

RESULTS

We found that PTX in PC3 human prostate cancer cells induces significant apoptosis per se and increases that generated by DTX, while at the same time it reduces the senescence caused by the chemotherapy and increases caspases-3,-8, and -9 activity in PTX + DTX-treated cells. Both treatments blocked the PC3 cell in the G1 phase.

CONCLUSIONS

Our results show that PTX sensitizes prostate tumor cells to apoptosis induced by DTX. Taken together, the results support the concept of chemotherapy with rational molecular bases.

Pentoxifylline Sensitizes Cisplatin-Resistant Human Cervical Cancer Cells to Cisplatin Treatment: Involvement of Mitochondrial and NF-Kappa B Pathways

Background

Cervical cancer continues to be a major public health problem worldwide, and Cisplatin is used as first-line chemotherapy for this cancer; however, malignant cells exposed to CISplatin (CIS) become insensitive to the effects of this drug. PenToXifylline (PTX) is a xanthine that sensitizes several types of tumor cells to apoptosis induced by antitumor drugs, such as Adriamycin, Carboplatin, and CIS. The effects of PTX on tumor cells have been related to the disruption of the NF-κB pathway, thus preventing the activation of cell survival mechanisms such as the expression of anti-apoptotic genes, the secretion of proinflammatory interleukins, and growth factors.

Objective

In this work, we studied the antitumor proprieties of PTX in human SiHa cervical carcinoma cells resistant to CIS.

Materials and Methods

SiHa and HeLa cervical cancer cells and their CIS-resistant derived cell lines (SiHaCIS-R and HeLaCIS-R, respectively) were used as in-vitro models. We studied the effects of PTX alone or in combination with CIS on cell viability, apoptosis, caspase-3, caspase-8, and caspase-9 activity, cleaved PARP-1, anti-apoptotic protein (Bcl-2 and Bcl-xL) levels, p65 phosphorylation, cadmium chloride (CdCl₂) sensitivity, Platinum (Pt) accumulation, and glutathione (GSH) levels, as well as on the gene expression of GSH and drug transporters (influx and efflux).

Results

PTX sensitized SiHaCIS-R cells to the effects of CIS by inducing apoptosis, caspase activation, and PARP-1 cleavage. PTX treatment also decreased p65 phosphorylation, increased Pt levels, depleted GSH, and downregulated the expression of the ATP7A, ATP7B, GSR, and MGST1 genes.

Conclusion

PTX reverses the acquired phenotype of CIS resistance close to the sensitivity of parental SiHa cells.

Implications of miRNAs on TGF-β/TAK1/mTOR pathway in mediating the renoprotective effects of pentoxifylline against cisplatin-induced nephrotoxicity in rats

Cisplatin (CIS)-mediated nephrotoxicity is induced via transforming growth factor-beta (TGF-β) and TGF-β-activated kinase (TAK1). TGF-β and TAK1 are known to interact with microRNA-let-7b and microRNA-26b, respectively. Additionally, TGF-β1 is reported to down-regulate the autophagy marker microtubule-associated protein 1 light chain 3-II (LC3-II) through upregulation of microRNA-34a. Pentoxifylline (PTX) anti-inflammatory effects are mediated via suppressing TGF-β and regulating mammalian target of rapamycin (mTOR). The current study aimed to investigate the involvement of microRNAs let-7b, 26b, and 34a, and the modulating impact of PTX on CIS-induced nephrotoxicity. Moreover, we aimed at examining the ability of PTX to interact with TGF-β receptor-1 (TGFβR-1), and TAK1, and examine its ability to downgrade the previously reported toxicities. Hence, the expression of the aforementioned microRNAs, and protein levels of TGFβR-1, TGF-β1, TAK1, mTOR, LC3-II, and NF-κB were assessed. Molecular docking studies of PTX on TGFβR-1 and TAK1 were also executed. CIS induced TGF-β1, with down-regulation of microRNA-let-7b and -26b, and up-regulation of microRNA-34a. TGFβR-1, TAK1, and mTOR levels were increased, while LC3-II level was decreased. PTX significantly protected renal cells against CIS-induced changes as indicated by reverting the level of the investigated parameters, while exhibiting an antagonistic effect on TGFβR-1 and TAK1. Our results postulate a possible role of epigenetic regulation of CIS-induced nephrotoxicity through the investigated microRNAs proposing them as potential future targets for controlling this serious toxicity. PTX was able to shield CIS-induced toxicity possibly through blocking TGF-β pathway, while promoting autophagy in a TAK1 independent manner with the involvement of the examined microRNAs.

A Matter of Choice: Inhibition of c-Rel Shifts Neuronal to Oligodendroglial Fate in Human Stem Cells

The molecular mechanisms underlying fate decisions of human neural stem cells (hNSCs) between neurogenesis and gliogenesis are critical during neuronal development and neurodegenerative diseases. Despite its crucial role in the murine nervous system, the potential role of the transcription factor NF-κB in the neuronal development of hNSCs is poorly understood. Here, we analyzed NF-κB subunit distribution during glutamatergic differentiation of hNSCs originating from neural crest-derived stem cells. We observed several peaks of specific NF-κB subunits. The most prominent nuclear peak was shown by c-REL subunit during a period of 2–5 days after differentiation onset. Furthermore, c-REL inhibition with pentoxifylline (PTXF) resulted in a complete shift towards oligodendroglial fate, as demonstrated by the presence of OLIG2⁺/O4⁺-oligodendrocytes, which showed PDGFRα, NG2 and MBP at the transcript level. In addition c-REL impairment further produced a significant decrease in neuronal survival. Transplantation of PTXF-treated predifferentiated hNSCs into an ex vivo oxidative-stress-mediated demyelination model of mouse organotypic cerebellar slices further led to integration in the white matter and differentiation into MBP⁺ oligodendrocytes, validating their functionality and therapeutic potential. In summary, we present a human cellular model of neuronal differentiation exhibiting a novel essential function of NF-κB-c-REL in fate choice between neurogenesis and oligodendrogenesis which will potentially be relevant for multiple sclerosis and schizophrenia.

Combination of pentoxifylline and α-galactosylceramide with radiotherapy promotes necro-apoptosis and leukocyte infiltration and reduces the mitosis rate in murine melanoma

Despite the success for the treatment of melanoma such as targeted molecular therapy, the use of such treatments are expensive For this reason, this study was carried out to explore the anti-cancer properties of available drugs that are able to modify the melanoma prognosis. The study was conducted in two phases: Evaluation of pharmacological effects of pentoxifylline (PTX) administered above (60 mg/kg) which is the therapeutic dose that is aimed at reducing the side-effect of radiotherapy, and of α- galactosylceramide (GalCer) administered at 100 μg/kg, as well as their combination using a murine model (BDF1 mice) of melanoma cell line (B16-F1, ATCC). For the radiotherapy phase, 9 Gy was applied in the tumor area, before (3 days), during (30 min) and after (3 days) the PTX + GalCer treatment. In both study phases, the mitosis rate, leukocyte infiltration and necro-apoptosis were assessed using histological and immunohistochemical approach and tumor volume evaluation as biomarkers. All treatments showed good prognosis results estimated as reduction of mitosis rate (PTX + GalCer after radiotherapy and GalCer), increased leukocyte infiltrate (PTX + GalCer after radiotherapy and GalCer) and necro-apoptosis augmentation (PTX + GalCer after radiotherapy and radiotherapy control). Nevertheless, a lower development of tumor volume was found in GalCer treatment. In this way, it is possible to suggest that the integrated treatment with immuno-stimulators such as GalCer, plus drug used for peripheral vascular disease (PTX) after radiotherapy is probably an alternative for controlling aggressive melanoma in murine model.

Pentoxifylline Enhances the Apoptotic Effect of Carboplatin in Y79 Retinoblastoma Cells

BACKGROUND/AIM

Retinoblastoma (RB) is the most common primary intraocular malignancy. Carboplatin (CPt) is a DNA damage-inducing agent that is widely used for the treatment of RB. Unfortunately, this drug also activates the transcription factor nuclear factor-kappa B (NF-ĸB), leading to promotion of tumor survival. Pentoxifylline (PTX) is a drug that inhibits the phosphorylation of I kappa B-alpha (IĸBα) in serines 32 and 36, and this disrupts NF-ĸB activity that promotes tumor survival. The goal of this study was to evaluate the effect of the PTX on the antitumor activity of CPt.

MATERIALS AND METHODS

Y79 RB cells were treated with CPt, PTX, or both. Cell viability, apoptosis, loss of mitochondrial membrane potential, the activity of caspase-9, -8, and -3, cytochrome c release, cell-cycle progression, p53, and phosphorylation of IĸBα, and pro- and anti-apoptotic genes were evaluated.

RESULTS

Both drugs significantly affected the viability of the Y79 RB cells in a time- and dose-dependent manner. The PTX+CPt combination exhibited the highest rate of apoptosis, a decrease in cell viability and significant caspase activation, as well as loss of mitochondrial membrane potential, release of cytochrome c, and increased p53 protein levels. Cells treated with PTX alone displayed decreased I kappa B-alpha phosphorylation, compared to the CPt treated group. In addition, the PTX+CPt combination treatment induced up-regulation of the proapoptotic genes Bax, Bad, Bak, and caspases- 3, -8, and -9, compared to the CPt and PTX individual treated groups.

CONCLUSION

PTX induces apoptosis per se and increases the CPt-induced apoptosis, augmenting its antitumor effectiveness.

Autophagy-induced senescence is regulated by p38α signaling

Apoptosis and senescence are two mutually exclusive cell fate programs that can be activated by stress. The factors that instruct cells to enter into senescence or apoptosis are not fully understood, but both programs can be regulated by the stress kinase p38α. Using an inducible system that specifically activates this pathway, we show that sustained p38α activation suffices to trigger massive autophagosome formation and to enhance the basal autophagic flux. This requires the concurrent effect of increased mitochondrial reactive oxygen species production and the phosphorylation of the ULK1 kinase on Ser-555 by p38α. Moreover, we demonstrate that macroautophagy induction by p38α signaling determines that cancer cells preferentially enter senescence instead of undergoing apoptosis. In agreement with these results, we present evidence that the induction of autophagy by p38α protects cancer cells from chemotherapy-induced apoptosis by promoting senescence. Our results identify a new mechanism of p38α-regulated basal autophagy that controls the fate of cancer cells in response to stress.

Chemical composition and cytotoxic screening of Musa cavendish green peels extract: Antiproliferative activity by activation of different cellular death types

Musa cavendish, commonly known as banana, is a fruit with nutritional and therapeutic properties. We investigated the chemical composition and in vitro cytotoxic effect of M. cavendish green peel extract (MHE) on cancer cells for the first time. The compounds characterization was performed by HPLC-UV/Vis and FIA-ESI-IT-MSⁿ. We investigated in vitro cytotoxic effect of Musa cavendish green peels extract (MHE) in HepG2, A-375, MCF-7 and Caco-2 cancer cells. We evaluated the effect of MHE on proliferation of different cell lines through apoptosis, necrosis, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) content determination. We identified 12 compounds from different classes in the extract, including derivatives of phenolic acids, aglycone flavonoids, glycoside flavonoids and catecholamines. Our results indicate that MHE exerts, after 48 h treatment, an accentuated antiproliferative effect from the dose of 100 μg/mL in all cell lines tested. In HepG2 cells, these effects were related to the induction of cell death, both necrotic and apoptotic, and remarkable changes in cell morphology. Depolarization of MMP and high ROS content were also observed in the cells in a dose-dependent manner. Our results show that MHE may be used as a source of new drugs with anticancer activity.

Effect of rutin on cisplatin-induced damage in human mesangial cells via apoptotic pathway

Cisplatin (CP) is one of the most effective and widely used compounds in the treatment of disease, including cancer, but is known to induce toxicity in patients. Rutin (RUT) is a flavonoid glycoside from Sophora japonica L. that has been shown to possess antioxidative, anti-inflammatory, and antiviral properties. RUT is also known to attenuate cardiotoxicity, isoproterenol-induced cardiac fibrosis, and ischemia/reperfusion-associated hemodynamic alteration, and prevents high glucose-induced renal glomerular endothelial hyperpermeability. In this study, we investigated the effect of RUT on CP-induced nephrotoxicity. CP was used to induce toxicity in human mesangial cells (HMCs), HMCs were pretreated with different concentrations of RUT before being exposed to 10 μg/mL of CP. A positive group was pretreated with antioxidant agent N-acetylcysteine prior to CP administration. At doses between 12.5 and 25 μM, RUT prevented CP-induced reduction in cell viability. Treatment with RUT suppressed intracellular reactive oxygen species and malonic dialdehyde levels and inhibited cell apoptosis. RUT reversed the CP-induced upregulation of p53, cleaved-caspase-3, and increased pro-caspase-3 and pro-caspase-9 levels. In conclusion, the RUT can relieve CP-induced nephrotoxicity by inhibiting the p53/caspase signaling pathway.

Pentoxifylline Added to Steroid Window Treatment Phase Modified Apoptotic Gene Expression in Pediatric Patients With Acute Lymphoblastic Leukemia

Pentoxifylline is a xanthine that possesses antitumor properties and that can induce higher apoptosis in the leukemic cells of pediatric patients with acute lymphoblastic leukemia (ALL) during treatment with prednisone. We conducted a phase 1 pilot, controlled, randomized trial to evaluate the gene expression modified by pentoxifylline during the steroid window of induction to remission phase in patients newly diagnosed with ALL. Experimental and control treatments induced broad changes in the gene expression profile. Patients who received just prednisone upregulated 377 and downregulated 344 genes, in contrast with patients treated with the experimental treatment (combination of prednisone and pentoxifylline), who demonstrated upregulation of 1319 and downregulation of 1594 genes. The most important genes modified in this pathway are those with proapoptotic activity, the majority of these overexpressed. Thus, the addition of pentoxifylline to the treatment with prednisone during steroid window in patients with ALL modified the gene expression profile and changed different signal pathways of the leukemic cell. The combination of both drugs represents a therapeutic alternative for potentiating antileukemic therapy.

Synergistic effects of cisplatin-caffeic acid induces apoptosis in human cervical cancer cells via the mitochondrial pathways

Cervical cancer (CxCa) is a major health problem globally and is associated with the presence of human papillomavirus infection. Cisplatin (CDDP) is a platinum-based chemotherapeutic agent. Owing to its side effects and drug-resistance, novel anticancer agents with lower toxicity, including caffeic acid (CFC), are of interest. However, the effects of CDDP and CFC in combination are, to the best of our knowledge, uninvestigated. The present study investigated the effectiveness of CDDP and CFC in combination and its mechanism of action on four human cervical cancer cell lines, which were compared with the Chlorocebus sabaeus normal kidney Vero cell line. Cell viability was evaluated using a sulforhodamine B assay. Caspase-Glo assay kits, measuring the activity of caspases-3, -7, -8 and -9, were used to detect caspase activation in HeLa and CaSki cell lines in response to CDDP and CFC in combination. The results revealed that CDDP and CFC alone reduced the proliferation of HeLa, CaSki, SiHa and C33A cell lines. Treatment with CFC exhibited no significant cytotoxicity towards Vero cells. In addition, CDDP-CFC significantly inhibited cell growth of HeLa and CaSki cell lines. In HeLa and CaSki cell lines, a combination index <1 for CDDP and CFC indicated the synergistic growth inhibition; the combination of the two also significantly increased expression of caspase-3, -7 and -9. In conclusion, CFC may be a candidate anticancer agent that, when use in combination, may increase the therapeutic efficacy of CDDP.

Combination of graphene oxide-silver nanoparticle nanocomposites and cisplatin enhances apoptosis and autophagy in human cervical cancer cells

BACKGROUND

Cisplatin (Cis) is a widely used chemotherapeutic drug for treating a variety of cancers, due to its ability to induce cell death in cancer cells significantly. Recently, graphene and its modified nanocomposites have gained much interest in cancer therapy, due to their unique physicochemical properties. The objective of this study was to investigate the combination effect of Cis and a reduced graphene oxide-silver nanoparticle nanocomposite (rGO-AgNPs) in human cervical cancer (HeLa) cells.

MATERIALS AND METHODS

We synthesized AgNPs, rGO, and rGO-AgNP nanocomposites using C-phycocyanin. The synthesized nanomaterials were characterized using various analytical techniques. The anticancer properties of the Cis, rGO-AgNPs, and combination of Cis and rGO-AgNPs were evaluated using a series of cellular assays, such as cell viability, cell proliferation, LDH leakage, reactive oxygen species generation, and cellular levels of oxidative and antioxidative stress markers such as malondialdehyde, glutathione, SOD, and CAT. The expression of proapoptotic, antiapoptotic, and autophagy genes were measured using real-time reverse-transcription polymerase chain reaction.

RESULTS

The synthesized AgNPs were well dispersed, homogeneous, and spherical, with an average size of 10 nm and uniformly distributed on graphene sheets. Cis, GO, rGO, AgNPs, and rGO-AgNPs inhibited cell viability in a dose-dependent manner. The combination of Cis and rGO-AgNPs showed significant effects on cell proliferation, cytotoxicity, and apoptosis. The combination of Cis and rGO-AgNPs had more pronounced effects on the expression of apoptotic and autophagy genes, and also significantly induced the accumulation of autophagosomes and autophagolysosomes, which was associated with the generation of reactive oxygen species.

CONCLUSION

Our findings substantiated rGO-AgNPs strongly potentiating Cis-induced cytotoxicity, apoptosis, and autophagy in HeLa cells, and hence rGO-AgNPs could be potentially applied to cervical cancer treatment as a powerful synergistic agent with Cis or any other chemotherapeutic agents.

The effect of pentoxifylline on L-1 sarcoma tumor growth and angiogenesis in Balb/c mice

Methyloxantines are present in many herbs and vegetal foods, among them in tea, coffee and chocolate. Previous studies revealed that theophylline and theobromine have anti-angiogenic properties. Anti-tumor properties of theobromine were also described. Pentoxifylline (3,7-dimethyl-1-(5-oxohexyl)xanthine, PTX) is a synthetic xanthine derivative. It is a phosphodiesterase inhibitor and has various anti-inflammatory abilities. Pentoxifylline is widely used in therapy of inflammatory arterial diseases such as intermittent claudication of upper and lower limbs as well as in coronary heart disease. The aim of our research was to evaluate the effect of pentoxifylline (individually and in combination with non-steroidal anti-inflammatory drug sulindac), on L-1 sarcoma angiogenic activity and tumor formation in syngeneic Balb/c mice. Pre-incubation of tumor cells for 90 min with various PTX concentrations resulted in dose-dependent decrease of their ability to induce newly-formed blood vessels after transplantation into the skin of recipient mice. Administration of PTX to mice, recipients of tumor cells, slows tumor growth and reduces its volume. Synergistic inhibitory effect of PTX and sulindac, expressed as % of tumors sixth and thirteen day after subcutaneous grafting of L-1 sarcoma into syngeneic Balb/c mice, was observed.

Cytoplasmic RAP1 mediates cisplatin resistance of non-small cell lung cancer

Cytotoxic chemotherapy agents (e.g., cisplatin) are the first-line drugs to treat non-small cell lung cancer (NSCLC) but NSCLC develops resistance to the agent, limiting therapeutic efficacy. Despite many approaches to identifying the underlying mechanism for cisplatin resistance, there remains a lack of effective targets in the population that resist cisplatin treatment. In this study, we sought to investigate the role of cytoplasmic RAP1, a previously identified positive regulator of NF-κB signaling, in the development of cisplatin resistance in NSCLC cells. We found that the expression of cytoplasmic RAP1 was significantly higher in high-grade NSCLC tissues than in low-grade NSCLC; compared with a normal pulmonary epithelial cell line, the A549 NSCLC cells exhibited more cytoplasmic RAP1 expression as well as increased NF-κB activity; cisplatin treatment resulted in a further increase of cytoplasmic RAP1 in A549 cells; overexpression of RAP1 desensitized the A549 cells to cisplatin, and conversely, RAP1 depletion in the NSCLC cells reduced their proliferation and increased their sensitivity to cisplatin, indicating that RAP1 is required for cell growth and has a key mediating role in the development of cisplatin resistance in NSCLC cells. The RAP1-mediated cisplatin resistance was associated with the activation of NF-κB signaling and the upregulation of the antiapoptosis factor BCL-2. Intriguingly, in the small portion of RAP1-depleted cells that survived cisplatin treatment, no induction of NF-κB activity and BCL-2 expression was observed. Furthermore, in established cisplatin-resistant A549 cells, RAP1 depletion caused BCL2 depletion, caspase activation and dramatic lethality to the cells. Hence, our results demonstrate that the cytoplasmic RAP1–NF-κB–BCL2 axis represents a key pathway to cisplatin resistance in NSCLC cells, identifying RAP1 as a marker and a potential therapeutic target for cisplatin resistance of NSCLC.

Oxidative Stress Triggered by Apigenin Induces Apoptosis in a Comprehensive Panel of Human Cervical Cancer-Derived Cell Lines

Recently, the cytotoxic effects of apigenin (4′,5,7-trihydroxyflavone), particularly its marked inhibition of cancer cell viability both in vitro and in vivo, have attracted the attention of the anticancer drug discovery field. Despite this, there are few studies of apigenin in cervical cancer, and these studies have mostly been conducted using HeLa cells. To evaluate the possibility of apigenin as a new therapeutic candidate for cervical cancer, we evaluated its cytotoxic effects in a comprehensive panel of human cervical cancer-derived cell lines including HeLa (human papillomavirus/HPV 18-positive), SiHa (HPV 16-positive), CaSki (HPV 16 and HPV 18-positive), and C33A (HPV-negative) cells in comparison to a nontumorigenic spontaneously immortalized human epithelial cell line (HaCaT). Our results demonstrated that apigenin had a selective cytotoxic effect and could induce apoptosis in all cervical cancer cell lines which were positively marked with Annexin V, but not in HaCaT (control cells). Additionally, apigenin was able to induce mitochondrial redox impairment, once it increased ROS levels and H₂O₂, decreased the Δψm, and increased LPO. Still, apigenin was able to inhibit migration and invasion of cancer cells. Thus, apigenin appears to be a promising new candidate as an anticancer drug for cervical cancer induced by different HPV genotypes.

Pentoxifylline Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats: Possibly via Inhibiting TLR 4/NF-κB Signaling Pathway

Early brain injury (EBI) after subarachnoid hemorrhage (SAH) generally causes significant and lasting damage. Pentoxifylline (PTX), a nonselective phosphodiesterase inhibitor, has shown anti-inflammatory and neuroprotective properties in several brain injury models, but the role of PTX with respect to EBI following SAH remains uncertain. The purpose of this study was to investigate the effects of PTX on EBI after SAH in rats. Adult male Sprauge-Dawley rats were randomly assigned to the sham and SAH groups. PTX (30 or 60 mg/kg) or an equal volume of the administration vehicle (normal saline) was administrated at 30 min intervals following SAH. Neurological scores, brain edema, and neural cell apoptosis were evaluated. In order to explore other mechanisms, changes in the toll-like receptor 4 (TLR4) and the nuclear factor-κB (NF-κB) signaling pathway, in terms of the levels of apoptosis-associated proteins, were also investigated. We found that administration of PTX (60 mg/kg) notably improved neurological function and decreased brain edema at both 24 and 72 h following SAH. Treatment with PTX (60 mg/kg) significantly inhibited the protein expressions of TLR4, NF-κB, MyD88 and the downstream pro-inflammatory cytokines, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). PTX also significantly reduced neural cell death and BBB permeability. Our observations may be the first time that PTX has been shown to play a neuroprotective role in EBI after SAH, potentially by suppressing the TLR4/NF-κB inflammation-related pathway in the rat brain.

Bothrops jararaca and Bothrops erythromelas Snake Venoms Promote Cell Cycle Arrest and Induce Apoptosis via the Mitochondrial Depolarization of Cervical Cancer Cells

Bothrops jararaca (BJ) and Bothrops erythromelas (BE) are viper snakes found in South-Southeast and Northeast regions of Brazil, respectively. Snake venoms are bioactive neurotoxic substances synthesized and stored by venom glands, with different physiological and pharmacological effects, recently suggesting a possible preference for targets in cancer cells; however, mechanisms of snakes have been little studied. Here, we investigated the mechanism responsible for snake crude venoms toxicity in cultured cervical cancer cells SiHa and HeLa. We show that BJ and BE snake crude venoms exert cytotoxic effects to these cells. The percentage of apoptotic cells and cell cycle analysis and cell proliferation were assessed by flow cytometry and MTT assay. Detection of mitochondrial membrane potential (Rhodamine-123), nuclei morphological change, and DNA fragmentation were examined by staining with DAPI. The results showed that both the BJ and BE venoms were capable of inhibiting tumor cell proliferation, promoting cytotoxicity and death by apoptosis of target SiHa and HeLa cells when treated with BJ and BE venoms. Furthermore, data revealed that both BJ venoms in SiHa cell promoted nuclear condensation, fragmentation, and formation of apoptotic bodies by DAPI assay, mitochondrial damage by Rhodamine-123, and cell cycle block in the G1-G0 phase. BJ and BE venoms present anticancer potential, suggesting that both Bothrops venoms could be used as prototypes for the development of new therapies.

Novel agents and treatment techniques to enhance radiotherapeutic outcomes in carcinoma of the uterine cervix

BACKGROUND

Survival of patients with locally advanced carcinoma cervix (LACC) using the current standard of concurrent chemo-radiotherapy (CCRT) has reached a plateau over the last two decades. Loco-regional failure in first two years of treatment completion and distant metastasis in the subsequent years has put the survival curves at a halt. Strategies of induction and adjuvant chemotherapy have yielded little as has any advancement in techniques of delivery of radiation therapy. This article aims at discussing the current existing literature as well as promising novel strategies to enhance radiotherapeutic outcomes in carcinoma of the uterine cervix.

METHODS

The review of English literature included phase I-III trials evaluating either a novel agent, novel application/modifications of an existing treatment regimen or an innovative treatment technique. The studies have been divided in to subsections with summary of most important findings at the end of each section.

RESULTS

Despite CCRT being the 'gold standard' treatment, several issues like optimum drug combination, schedule of drug delivery, combination with molecular targeted agents etc. remain undefined. Taxane, topoisomerase and gemcitabine based regimen needs to be further explored and compared with cisplatin based CCRT regimen. Several approaches like local delivery of cytotoxic agents, use of nano-medicine with CCRT are appearing on horizon with promises for the future. Therapies need to be designed based on the human papillomavirus titers of the patients and incorporation of radiosensitizers as an effective way of palliation with short course of radiotherapy may further enhance the radiotherapeutic outcomes.

CONCLUSIONS

The results of the studies with novel agents and treatment techniques appear promising. Further research in this arena including incorporation of cost-effectiveness analysis and quality of life issues in future trial designs are warranted.

Pentoxifylline as a modulator of anticancer drug doxorubicin. Part II: Reduction of doxorubicin DNA binding and alleviation of its biological effects

Anticancer drug doxorubicin is commonly used in cancer treatment. However, drug's severe side effects make toxicity reduction important matter. Another biologically active aromatic compound, pentoxifylline, can sequester aromatic compounds in stacking complexes reducing their bioactivity. This work deals with the problem of alleviating doxorubicin side effects by pentoxifylline. We employed a wide spectrum of prokaryotic and eukaryotic cellular assays. In addition, we used the doxorubicin-pentoxifylline mixed association constant to quantitatively assess pentoxifylline influence on the doxorubicin mutagenic activity. Obtained results indicate strong protective effects of pentoxifylline towards doxorubicin, observed on bacteria and human keratinocytes with no such effects observed on the cancer cells. It may be hypothesized that, considering much shorter half-life of pentoxifylline than doxorubicin, simultaneous administration of doxorubicin and pentoxifylline will lead to gradual release of doxorubicin from complexes with pentoxifylline to reach desired therapeutic concentration. Proposed results shed light on the possible doxorubicin chemotherapy modification and its side effects reduction without the loss of its therapeutic potential.

Tanshinone IIA enhances chemosensitivity of colon cancer cells by suppressing nuclear factor-κB

The aim of the present study was to investigate the effect and molecular mechanism of tanshinone IIA (TSA) on colon cancer cells. Cell viability was determined using Cell Counting kit-8 assay and the results demonstrated that TSA treatment significantly decreased the cell viability of HCT1116 and COLO205 cells in a dose-dependent manner. TSA treatment also sensitized HCT1116 and COLO205 cells to fluorouracil therapy in a concentration-dependent manner. Western blotting was performed in order to investigate the molecular mechanisms of TSA action and determine the level of phosporylated p65 and nuclear factor-κB (NF-κB)-regulated genes, including vascular endothelial growth factor (VEGF), c-Myc, cyclooxygenase-2 (COX-2) and B-cell lymphoma-2 (Bcl-2). The results revealed that TSA treatment greatly decreased the level of phosphorylated p65 in the nucleus, which indicated the inhibition of NF-κB activation by TSA treatment. TSA also decreased the expression levels of VEGF, c-Myc, COX-2 and Bcl-2. Furthermore, the inhibition of NF-κB activation with the specific inhibitor, pyrrolidine dithiocarbamate, increased the induction of cell death and chemosensitization effect of TSA in colon cancer cells. In conclusion, these results suggest that TSA induces cell death and chemosensitizes colon cancer cells through the suppression of NF-κB signaling.

Sensitization of ovarian cancer cells to cisplatin by gold nanoparticles

Recently we reported that gold nanoparticles (AuNPs) inhibit ovarian tumor growth and metastasis in mice by reversing epithelial-mesenchymal transition (EMT). Since EMT is known to confer drug resistance to cancer cells, we wanted to investigate whether anti-EMT property of AuNP could be utilized to sensitize ovarian cancer cells to cisplatin. Herein, we report that AuNPs prevent cisplatin-induced acquired chemoresistance and stemness in ovarian cancer cells and sensitize them to cisplatin. AuNPs inhibit cisplatin induced EMT, decrease the side population cells and key stem cell markers such as ALDH1, CD44, CD133, Sox2, MDR1 and ABCG2 in ovarian cancer cells. Mechanistically, AuNPs prevent cisplatin-induced activation of Akt and NF-κB signaling axis in ovarian cancer cells that are critical for EMT, stem cell maintenance and drug resistance. In vivo, AuNPs sensitize orthotopically implanted ovarian tumor to a low dose of cisplatin and significantly inhibit tumor growth via facilitated delivery of both AuNP and cisplatin. These findings suggest that by depleting stem cell pools and inhibiting key molecular pathways gold nanoparticles sensitize ovarian cancer cells to cisplatin and may be used in combination to inhibit tumor growth and metastasis in ovarian cancer.

Pentoxifylline as a modulator of anticancer drug doxorubicin. Part I: Reduction of doxorubicin DNA binding

Pentoxifylline--biologically active aromatic compound--has a well established capability to sequester aromatic ligands, such as an anticancer drug--doxorubicin--in mixed stacking aggregates. Formation of such hetero-complexes may influence biological activity of secluded drug. Presented work shows assessment of pentoxifylline influence on doxorubicin direct interactions with DNA employing biophysical methods. Achievement of this goal required statistical-thermodynamical model allowing numerical four-parameter analysis of experimental mixture--an issue that was successfully tackled by merging McGhee--von Hippel and Kapuscinski--Kimmel models. Results obtained with new model are well in agreement with data obtained with separate experiments with each of these two models and show reduction of doxorubicin in free (monomeric, dimeric) and complexed with DNA forms in favor of doxorubicin-pentoxifylline complexes with increasing pentoxifylline concentration. Developed model appears to be a universal tool allowing numerical analysis of mixtures containing self-aggregating ligand, DNA, and modulating agent.

Pentoxifylline during steroid window phase at induction to remission increases apoptosis in childhood with acute lymphoblastic leukemia

PURPOSE

Pentoxifylline (PTX) has been shown to increase chemotherapy-induced apoptosis. A clinical trial was developed to evaluate the effect of the addition of PTX to the induction steroid window phase in children with acute lymphoblastic leukemia (ALL).

METHODS

Thirty-two children were enrolled on this study. Children with a new diagnosis of ALL were randomly assigned to receive prednisone (PRD) 40 mg/m(2)/day only during the 7-day treatment pre-phase (PRD group, 11 patients) or to receive PRD with PTX (10 mg/kg/day) (PTX group, 11 patients); the control group included children with normal bone marrow (10 patients). Bone marrow aspiration (BMA) was performed at diagnosis (day -7) in all groups, and at day 0 (end of PRD window) for patients with ALL (PRD and PTX groups). Apoptosis was evaluated by flow cytometry (FC) using Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) stains. Statistical analysis was performed using the Mann-Whitney U test.

RESULTS

Apoptotic index at day -7 was similar in all groups. However, at day 0 post-treatment, apoptosis was significantly higher in the PTX group than in the PRD group (p < 0.001). There were no serious adverse effects associated with PTX.

CONCLUSIONS

PTX potentiates blast apoptosis induced by PRD in children with ALL during steroid window phase.

Protective effects of pentoxifylline on acute liver injury induced by thioacetamide in rats

Pentoxifylline (PTX) is a non-selective phosphodiesterase inhibitor with the effects of antioxidation, anti-inflammation and anti-fibrosis that has been shown to induce damage in liver. The purpose of this study is to investigate the effects and possible mechanisms of PTX on thioacetamide (TAA)-induced acute liver injury in rats. Male Sprague-Dawley (SD) rats were divided into four groups: control, PTX, TAA and PTX+TAA treated groups. Rats were administrated TAA together with or without PTX for a week and sacrificed 24 h after the last intragastric administration of PTX. Histopathological analysis was carried out. The liver function, the indices of oxidative stress including malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) in liver tissues, and pro-inflammatory cytokines expressions were examined. The mRNA level of NF-κB p65 in liver was also determined. PTX significantly attenuated TAA-induced liver injury. The serum transaminase and MDA levels were reduced while the levels of SOD and GSH were increased, as compared with the TAA-treated group. PTX also remarkably suppressed the secretions of pro-inflammatory cytokines and the nuclear factor-κB (NF-κB) activation induced by TAA. In addition, the histopathological analysis showed that the range and degree of liver tissue lesions were improved obviously in PTX treated group. Pentoxifylline could ameliorate the effects of thioacetamide-induced acute liver injury in rats by inhibiting oxidative stress, expressions of pro-inflammatory cytokines and NF-κB activation.

Phosphodiesterase inhibitor, pentoxifylline enhances anticancer activity of histone deacetylase inhibitor, MS-275 in human breast cancer in vitro and in vivo

MS-275, a histone deacetylase inhibitor (HDACi), is undergoing clinical trials for treatment of various cancers. Pentoxifylline, a nonselective phosphodiesterase (PDE) inhibitor, has been shown to increase the effectiveness of antitumor chemotherapy. In the present study, the potential anti-cancer activity of MS-275 in combination with pentoxifylline in panel of cell lines and human breast cancer xenograft model were examined. A Panel of cancer cell lines were treated with MS-275 and pentoxifylline to determine their impact on cellular proliferation, cell cycle regulation, apoptosis, anti-angiogenesis. The in vivo activities of MS-275 and pentoxifylline were assessed in a Matrigel plug angiogenesis model and human breast cancer (MDA-MB-231) xenograft model. Combination of MS-275 with pentoxifylline showed enhanced anti-proliferative activity in a panel of cancer cell lines (HCT 116, MCF-7, PC3 and MDA-MB-231). Apoptotic studies performed using, Hoechst staining and cell cycle analysis reveal that this combination at the lower concentrations induces apoptosis downstream of the HDAC inhibition and PDE regulation. Further, combination showed enhanced antiangiogenic activity in Matrigel tube formation assay using HUVECs and in Matrigel plug assay in vivo. A significant inhibition (P<0.001) of tumor growth was observed in mice bearing MDA-MB-231 breast cancer xenograft treated with the combination of MS-275 (5mg/kg p.o.) and pentoxifylline (60 mg/kg i.p.) than treatments alone, without much signs of toxicity. Taken together, our study demonstrated enhanced anticancer activity of MS-275 and pentoxifylline combination both in vitro and in vivo with reduced toxicity. However, further studies are required to understand the mechanism for this combination effect.

Phosphonomethyl iminodiacetic acid-conjugated cobalt oxide nanoparticles liberate Co(++) ion-induced stress associated activation of TNF-α/p38 MAPK/caspase 8-caspase 3 signaling in human leukemia cells

The aim of this work is to understand the potential health effects of metal nanoparticles by exposing human leukemic cell lines (jurkat, K562 and KG1A cells) to nanosize phosphonomethyl iminodiacetic acid coated cobalt oxide (PMIDA-CoO) NPs. The synthesized PMIDA-CoO NPs were characterized by XRD, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. Our results showed that exposure of leukemic cell lines to PMIDA-CoO NPs caused reactive oxygen species (ROS) generation by increasing the concentration of free Co(++) ions in cancer microenvironment. But at physiological pH, PMIDA-CoO liberates little amount of Co(++) ions into media and exerts lower toxicity to normal cells up to a certain dose. PMIDA-CoO NPs caused DNA damage in leukemic cell lines, which was reflected by an increase in apoptosis of jurkat, KG-1A and K562 cells. PMIDA-CoO NPs induced apoptosis by increasing pro-inflammatory cytokines, primarily TNF-α. The in vivo study shows that PMIDA-CoO NPs were efficiently killed DLA cells. These findings have important implications for understanding the potential anticancer property induced by surface-modified cobalt oxide nanoparticles.

Morinda citrifolia (Noni) alters oxidative stress marker and antioxidant activity in cervical cancer cell lines

BACKGROUND

Cervical cancer, the second most common cancer in women, has a high mortality rate. Cisplatin, an antitumor agent, is generally used for its treatment. However, the administration of cisplatin is associated with side effects and intrinsic resistance. Morinda citrifolia (Noni), a natural plant product, has been shown to have antioxidant activities in vitro and in vivo.

MATERIALS AND METHODS

Both HeLa and SiHa cervical cancer cell lines were treated with 10% Noni, 10 mg/dl cisplatin, or a combination of both 10% Noni and 10 mg/dl cisplatin for 24 hours. Post culturing, the cells were pelleted and stored at -70oC for malondialdehyde and catalase assays.

RESULTS

On treatment with Noni, CP, and their combination, the level of MDA decreased by 0.76 fold, 0.49 fold, and 0.68 fold respectively in HeLa cells; and by 0.93 fold, 0.67 fold, and 0.79 fold respectively in SiHa cells, as compared to their controls; whereas catalase activity increased by 1.61 fold, 0.54 fold, and 2.35 fold, respectively in HeLa cells; and by 0.98 fold, 0.39 fold, and 1.85 fold respectively in SiHa cells.

CONCLUSIONS

A decrease in level of lipid peroxidation and an increase in catalase activity were observed with Noni by itself and the effect ameliorated changes observed with cisplatin when given in combination.

Sensitization of U937 leukemia cells to doxorubicin by the MG132 proteasome inhibitor induces an increase in apoptosis by suppressing NF-kappa B and mitochondrial membrane potential loss

Background

The resistance of cancerous cells to chemotherapy remains the main limitation for cancer treatment at present. Doxorubicin (DOX) is a potent antitumor drug that activates the ubiquitin-proteasome system, but unfortunately it also activates the Nuclear factor kappa B (NF-кB) pathway leading to the promotion of tumor cell survival. MG132 is a drug that inhibits I kappa B degradation by the proteasome-avoiding activation of NF-кB. In this work, we studied the sensitizing effect of the MG132 proteasome inhibitor on the antitumor activity of DOX.

Methods

U937 human leukemia cells were treated with MG132, DOX, or both drugs. We evaluated proliferation, viability, apoptosis, caspase-3, -8, and −9 activity and cleavage, cytochrome c release, mitochondrial membrane potential, the Bcl-2 and Bcl-XL antiapoptotic proteins, senescence, p65 phosphorylation, and pro- and antiapoptotic genes.

Results

The greatest apoptosis percentage in U937 cells was obtained with a combination of MG132 + DOX. Likewise, employing both drugs, we observed a decrease in tumor cell proliferation and important caspase-3 activation, as well as mitochondrial membrane potential loss. Therefore, MG132 decreases senescence, p65 phosphorylation, and the DOX-induced Bcl-2 antiapoptotic protein. The MG132 + DOX treatment induced upregulation of proapoptotic genes BAX, DIABLO, NOXA, DR4, and FAS. It also induced downregulation of the antiapoptotic genes BCL-XL and SURVIVIN.

Conclusion

MG132 sensitizes U937 leukemia cells to DOX-induced apoptosis, increasing its anti-leukemic effectiveness.

The inhibitory effects of phenolic and terpenoid compounds from Baccharis trimera in Siha cells: differences in their activity and mechanism of action

Baccharis trimera is used in folk medicine as a tea for digestive and liver diseases. It possesses anti-inflammatory and antioxidant properties that are related to the presence of phenolic compounds. The aim of this work was to investigate the anti-proliferative properties of phenolic (PHE) and terpenoid (SAP) compounds from B. trimera on human cervical cancer. The treatment of SiHa cells with PHE for 24 h suppressed colony formation in a dose-dependent manner, inhibited proliferation and inhibited cell motility. Although SAP inhibited the proliferation of SiHa cells in a dose-dependent manner, it increased colony formation and did not inhibit cell motility. PHE and SAP also promoted a significant increase in lactate dehydrogenase levels in the culture medium in a dose-dependent manner, indicating a loss of cell membrane integrity. Moreover, PHE promoted necrotic cell death, whereas SAP induced apoptosis. These compounds are new anticancer prototypes due their significant anticancer activity demonstrated herein.

Curbing the focal adhesion kinase and its associated signaling events by pentoxifylline in MDA-MB-231 human breast cancer cells

Pentoxifylline (PTX) is a methylxanthine derivative currently being used in the treatment of peripheral vascular diseases. Recently, we had evaluated its action in human MDA-MB-231 breast cancer cells. PTX exhibited anti-metastatic activity by affecting key processes such as proliferation, adhesion, migration, invasion and apoptosis. In light of the preliminary findings, the present work accounts for the possible mechanistic insights of the pathways affected by PTX. Aberrant Focal Adhesion Kinase (FAK) signaling forms a key determinant in breast cancer and in view of this fact we had investigated downstream processes regulated by FAK. PTX at sub-toxic doses lowers the level of activated FAK, Extracellular Regulated Kinase or Mitogen Activated Protein Kinase (ERK/MAPK), Protein Kinase B (PKB/Akt) affecting cellular proliferation and survival. It blocks G1/S phase of cell cycle by inhibiting the expression of Cyclin D1/Cdk6. Further, it modulates the activities of RhoGTPases and alters actin organization resulting in decreased motility. PTX also delays tumor growth and inhibited blood vessel formation in vivo. In purview of these findings, PTX surely qualifies as a suitable prospect in the intervention of breast cancer.

Suppression of apoptosis by pseudorabies virus Us3 protein kinase through the activation of PI3-K/Akt and NF-κB pathways

The pseudorabies virus (PRV) is a major viral disease that causes huge economic loss in the pig industry globally. Most viruses have been found to generate anti-apoptotic factors that facilitate cell survival in the early stages of infection. This study aimed to investigate the anti-apoptotic effects of PRV and study the underlying mechanisms in the early stage of infection. We investigated and compared whether the two PRV Us3 isoforms, Us3a and Us3b, could block apoptosis induced by virus infection, and further identified molecules involved in the signaling pathways. Our results demonstrated that PRV elicits 3-phosphoinositide dependent protein kinase-1/phosphatidylinositide 3-kinases/Akt (PDK-1/PI3-K/Akt)- and nuclear factor-κB (NF-κB)-dependent signaling in the early stage of infection. Inhibition of the PI3-K/Akt or NF-κB pathway enhanced cell death but no effect was observed on virus replication or PRV gene expression. Transiently-expressed GFP- or His-tagged PRV Us3a and Us3b cDNA protect cells against PRV-, avian reovirus- or bovine ephemeral fever virus-induced apoptosis in the cell lines. Us3a and Us3b transient over-expression upregulated several anti-apopototic signaling events, and the anti-apoptosis activity of Us3a is greater than that of Us3b. Kinase activity-deficient point or double point mutated Us3a lost the kinase activity of Us3a, which showed that kinase activity is required for the anti-apoptosis effect of Us3. Akt and NF-κB activation still occurred in UV-inactivated PRV- and cycloheximide-treated cells. In vivo study showed that PRV-infected trigeminal ganglion increases the expression of anti-apoptosis signaling molecules, including Akt, PDK-1 and IκBα, which is a similar result to that seen in the in vitro experiments. Our study suggests that signaling mechanisms may play important roles in PRV pathogenesis.

Plants and cervical cancer: an overview

INTRODUCTION

Cervical cancer, the second most common gynecological malignant tumor seriously harmful to the health of women, remains a leading cause of cancer-related death for women in developing countries. Although a large amount of scientific research has been reported on plants as a natural source of treatment agents for cervical cancer, it is currently scattered across various publications. A systematic summary and knowledge of future prospects are necessary to facilitate further plant studies for anti-cervical cancer agents.

AREAS COVERED

This review generalizes and analyzes the current knowledge on the anti-cervical cancer properties and mechanisms involved for plants, and discusses the future prospects for the application of these plants.

EXPERT OPINION

This review mainly focuses on the plants which have been scientifically tested in vitro and/or in vivo and proved as potential agents for the treatment of cervical cancer. The failure of conventional chemotherapy to reduce mortality as well as serious side effects involved makes natural products ideal candidates for exerting synergism and attenuation effects on anticancer drugs. Although the chemical components and mechanisms of action of natural plants with anti-cervical cancer potential have been investigated, many others remain unknown. More investigations and clinical trials are necessary to make use of these medical plants reasonably.

Nip the HPV encoded evil in the cancer bud: HPV reshapes TRAILs and signaling landscapes

HPV encoded proteins can elicit ectopic protein–protein interactions that re-wire signaling pathways, in a mode that promotes malignancy. Moreover, accumulating data related to HPV is now providing compelling substantiation of a central role played by HPV in escaping immunosurveillance and impairment of apoptotic response. What emerges is an intricate network of Wnt, TGF, Notch signaling cascades that forms higher-order ligand–receptor complexes routing downstream signaling in HPV infected cells. These HPV infected cells are regulated both extracellularly by ligand receptor axis and intracellularly by HPV encoded proteins and impair TRAIL mediated apoptosis. We divide this review into different sections addressing how linear signaling pathways integrate to facilitate carcinogenesis and compounds that directly or indirectly reverse these aberrant interactions offer new possibilities for therapy in cancer. Although HPV encoded proteins mediated misrepresentation of pathways is difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can target dysregulated pathways in HPV infected cervical cancer cells, thus setting the stage for preclinical models and clinical trials.

2,4-bis (p-hydroxyphenyl)-2-butenal (HPB242) induces apoptosis via modulating E7 expression and inhibition of PI3K/Akt pathway in SiHa human cervical cancer cells

The Maillard reaction is a chemical reaction occurring between an amino acid and a reducing sugar, usually requiring thermal processing. Maillard reaction products (MRPs) have antioxidant, antimutagenic, and antibacterial effects, and although 2,4-bis (p-hydroxyphenyl)-2-butenal (HPB242), a fructose-tyrosine MRP, appears to inhibit proliferation of cancer cells, its mechanism of action has not been studied in detail. We found that HPB242 treatment modulated expression of cyclins and tumor suppressor genes in SiHa human cervical cancer cell lines: cyclins and phospho-pRB were downregulated, whereas the expression of CDK inhibitors and p53 was enhanced. HPB242 induced apoptosis dose-dependently by suppressing E7 expression and leading to sub-G1 cell-cycle arrest in SiHa cell lines; treatment also led to the proteolytic cleavage of caspase-3, -9, and poly (ADP-ribose) polymerase. Moreover, HPB242 upregulated Fas expression, altered expressions of pro- and antiapoptotic factors, and also inhibited nuclear translocation of nuclear factor κB and phosphorylation of IκB. HPB242 treatment decreased phosphatidyl inositol-3 kinase and p-Akt expression levels, demonstrating that this survival pathway may also be inhibited by HPB242. Cumulatively, HPB242 promotes apoptosis by influencing E7 expression, inducing cell-cycle arrest at sub-G1 phase, and promoting both intrinsic (mitochondrial) and extrinsic (Fas-dependent) apoptosis in SiHa human cervical cancer cells.

Pentoxifylline inhibits melanoma tumor growth and angiogenesis by targeting STAT3 signaling pathway

Pentoxifylline (PTX), a phosphodiesterase inhibitor, has been shown to have anti-metastatic or anti-angiogenic activity against many human cancers. However, the underlying mechanisms are unknown. In this study, we report that, PTX at sub-toxic doses can inhibit melanoma tumor growth and angiogenesis by targeting the STAT3 signaling pathway. Despite minimal cytotoxicity against normal cells, PTX suppressed phosphorylation and DNA binding of STAT3 in a dose-dependent manner. Also, PTX inhibited phosphorylation of the upstream kinases JAK1 and JAK2 and increased the expression of pSHP2 phosphatase. Expression of various STAT3 regulated gene products, such as cylinD1, CDK6, cMyc, BclXL, and VEGF was downregulated following PTX treatment. Tumor microenvironment favours tumor growth and metastasis. PTX alters tumor microenvironment by limiting IL-6 secretion and also by disrupting VEGF-VEGFR2 autocrine/paracrine signaling. PTX treatment significantly inhibited tumor growth and angiogenesis in intra-dermal xenograft mouse model in vivo without having any visible toxicity. These findings identified STAT3 signaling as a target of PTX and have thus, augmented its potential application in the treatment of melanoma and other cancers.

Pentoxifylline and the proteasome inhibitor MG132 induce apoptosis in human leukemia U937 cells through a decrease in the expression of Bcl-2 and Bcl-XL and phosphorylation of p65

Background

In Oncology, the resistance of the cancerous cells to chemotherapy continues to be the principal limitation. The nuclear factor-kappa B (NF-κB) transcription factor plays an important role in tumor escape and resistance to chemotherapy and this factor regulates several pathways that promote tumor survival including some antiapoptotic proteins such as Bcl-2 and Bcl-XL. In this study, we investigated, in U937 human leukemia cells, the effects of PTX and the MG132 proteasome inhibitor, drugs that can disrupt the NF-κB pathway. For this, we evaluated viability, apoptosis, cell cycle, caspases-3, -8, -9, cytochrome c release, mitochondrial membrane potential loss, p65 phosphorylation, and the modification in the expression of pro- and antiapoptotic genes, and the Bcl-2 and Bcl-XL antiapoptotic proteins.

Results

The two drugs affect the viability of the leukemia cells in a time-dependent manner. The greatest percentage of apoptosis was obtained with a combination of the drugs; likewise, PTX and MG132 induce G1 phase cell cycle arrest and cleavage of caspases -3,-8, -9 and cytochrome c release and mitochondrial membrane potential loss in U937 human leukemia cells. In these cells, PTX and the MG132 proteasome inhibitor decrease p65 (NF-κB subunit) phosphorylation and the antiapoptotic proteins Bcl-2 and Bcl-XL. We also observed, with a combination of these drugs overexpression of a group of the proapoptotic genes BAX, DIABLO, and FAS while the genes BCL-XL, MCL-1, survivin, IκB, and P65 were downregulated.

Conclusions

The two drugs used induce apoptosis per se, this cytotoxicity was greater with combination of both drugs. These observations are related with the caspases -9, -3 cleavage and G1 phase cell cycle arrest, and a decrease in p65 phosphorylation and Bcl-2 and Bcl-XL proteins. As well as this combination of drugs promotes the upregulation of the proapoptotic genes and downregulation of antiapoptotic genes. These observations strongly confirm antileukemic potential.