Perillyl alcohol as a radio-/chemosensitizer in malignant glioma

Molecular pharmacology and therapeutic advances of monoterpene perillyl alcohol

BACKGROUND

Perillyl alcohol (POH) is a aroma monoterpene commonly obtained from various plants' essential oil. Recently, increasing researches have demonstrated that POH may be useful, not only as flavor compound, but also as bioactive molecule because of a variety of biological activities.

PURPOSE

The aim of this review is to summarize the production, pharmacological activities and molecular mechanism, active derivatives, toxicity and parmacokinetics, and industrial application of POH.

METHODS

A systematic search of published articles up to January 2024 in Web of Science, China Knowledge Network, and PubMed databases is conducted using the following keywords: POH, POH derivatives, biological or pharmacological, production or synthesis, pharmacokinetics, toxicity and application.

RESULTS

Biotechnological production is considered to be a potential alternative approach to generate POH. POH provides diverse pharmacological benefits, including anticancer, antimicrobial, insecticidal, antioxidant, anti-inflammatory, hypotensive, vasorelaxant, antinociceptive, antiasthmatic, hepatoprotective effects, etc. The underlying mechanisms of action include modulation of NF-κB, JNK/c-Jun, Notch, Akt/mTOR, PI3K/Akt/eNOS, STAT3, Nrf2 and ERS response pathways, mitigation of mitochondrial dysfunction and membrane integrity damage, and inhibition of ROS accumulation, pro-inflammatory cytokines release and NLRP3 activation. What's more, the proteins or genes influenced by POH against diseases refer to Bax, Bcl-2, cyclin D1, CDK, p21, p53, HIF-1α, AP-1, caspase-3, M6P/IGF2R, PARP, VEGF, etc. Some clinical studies report that intranasal delivery of POH is a safe and effective treatment for cancer, but further clinical investigations are needed to confirm other health benefits of POH in human healthy. Depending on these health-promoting properties together with desirable flavor and safety, POH can be employed as dietary supplement, preservative and flavor additive in food and cosmetic fields, as building block in synthesis fields, as anticancer drug in medicinal fields, and as pesticides and herbicides in agricultural fields.

CONCLUSION

This review systematically summarizes the recent advances in POH and highlights its therapeutic effects and potential mechanisms as well as the clinical settings, which is helpful to develop POH into functional food and new candidate drug for prevention and management of diseases. Future studies are needed to conduct more biological activity studies of POH and its derivatives, and check their clinical efficacy and potential side effects.

Perillyl alcohol for pediatric TP53- and RAS-mutated SHH-medulloblastoma: an in vitro and in vivo translational pre-clinical study

PURPOSE

Inhalation of perillyl alcohol (POH) recently emerged as an investigational promising antiglioma strategy. However, little attention has been paid to its therapeutic potential for other brain tumors, especially in the pediatric setting.

METHODS

The effects of POH were explored in medulloblastoma cell models belonging to the SHH variant with activation of RAS (ONS-76) or with TP53 mutations (DAOY and UW402), by means of proliferation and invasion assays. Interactions with methotrexate, thiotepa, or ionizing radiation were also assessed. Mice bearing subcutaneous tumors were treated with intraperitoneal injections. Alternatively, animals with intracranial tumors were exposed to intranasal POH alone or combined with radiation. Tumor growth was measured by bioluminescence. Analyses of cytotoxicity to the nasal cavity were also performed, and the presence of POH in the brain, lungs, and plasma was surveyed through chromatography/mass spectrometry.

RESULTS

POH decreased cell proliferation and colony formation, with conspicuous death, though the invasive capacity was only affected in the NRAS-mutated cell line. Median-drug effect analysis displayed synergistic combinations with methotrexate. Otherwise, POH showed to be a reasonable radiosensitizer. In vivo, intraperitoneal injection significantly decreased tumor volume. However, its inhalation did not affect orthotopic tumors, neither alone or followed by cranial irradiation. Nasal cavity epithelium showed unimportant alterations, though, no traces of POH or its metabolites were detected in tissue samples.

CONCLUSION

POH presents robust in vitro antimedulloblastoma effects and sensitizes cell lines to other conventional therapeutics, reducing tumor volume when administered intraperitoneally. Nevertheless, further improvement of delivery devices and/or drug formulations are needed to better characterize its effectiveness through inhalation.

Photophysical Properties of Fluorescent Self-Assembled Peptide Nanostructures for Singlet Oxygen Generation

In this work, a drug delivery system for perillyl alcohol based on the peptide self-assembly containing 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6) as a fluorescent additive is obtained, and its photophysical characteristics as well as its release dynamics were studied by steady-state and time-resolved fluorescence spectroscopy. Results proved the dynamics of drug release from the peptide nanostructures and showed that the system formed by the self-assembled peptide and C6, along with perillyl alcohol, presents unique photophysical properties that can be exploited to generate singlet oxygen (1O2) upon irradiation, which is not achieved by the sole components. Through epifluorescence microscopy combined with time-correlated single photon counting fluorescence spectroscopy, the release mechanism was proven to occur upon peptide structure interconversion, which is controlled by environmental changes.

Induction of apoptosis by essential oil from P. missionis in skin epidermoid cancer cells

BACKGROUND

The genus Pamburus (Rutaceae) comprises the only species, Pamburus missionis (Wight) Swingle. Pamburus missionis is traditionally used in the treatment of swellings, chronic rheumatism, paralysis and puerperal diseases.

PURPOSE

The present study investigates the cancer chemotherapeutic potential of essential oil (EO) from P. missionis.

METHODS

EO was isolated by steam distillation and chemical composition was determined by GC-MS. Cell viability was used to detect cytotoxic activity. Mechanism of cell death was studied using Annexin V-FITC/PI binding, cell cycle analysis, measurement of MMP and ROS generation by flow cytometry. Expression of apoptosis related proteins was investigated by western blot.

RESULTS

GC-MS analysis of the essential oil revealed the presence of 51 components. The major components were β-Caryophyllene, 4(14),11-Eudesmadiene, Aromadendrene oxide-(2) and Phytol. EO inhibited the growth and colony formation ability of A431 and HaCaT cells. EO treatment induced nuclear condensation and loss of membrane integrity, DNA fragmentation, increase in sub-G1 DNA content and increase in intracellular ROS level. Inhibition of intracellular ROS by ascorbic acid and N-acetyl cysteine treatment blocked EO induced apoptosis, revealing that apoptotic activity was by ROS accumulation. EO induced apoptosis was found to be due to the loss of mitochondrial membrane potential (ΔΨm), increase in Bax/Bcl-2 ratio, release of cytochrome c and activation of caspases (cleaved form of caspase-3, caspase-8, caspase-9) and by PARP cleavage.

CONCLUSION

The present study revealed cancer chemotherapeutic potential of EO from P. missionis. EO induces cell death through intrinsic (mitochondrial) and extrinsic apoptotic pathway in A431 and HaCaT cells. These results suggest that EO could be used as a potential therapeutic agent for the treatment of skin epidermoid cancer.

Chemopreventive effect of myrtenal on bacterial enzyme activity and the development of 1,2-dimethyl hydrazine-induced aberrant crypt foci in Wistar Rats

Colon cancer remains as a serious health problem around the world despite advances in diagnosis and treatment. Dietary fibers are considered to reduce the risk of colon cancer as they are converted to short chain fatty acids by the presence of anaerobic bacteria in the intestine, but imbalanced diet and high fat consumption may promote tumor formation at different sites, including the large bowel via increased bacterial enzymes activity. The present study was conducted to characterize the inhibitory action of myrtenal on bacterial enzymes and aberrant crypt foci (ACF). Experimental colon carcinogenesis induced by 1,2-dimethylhydrazine is histologically, morphologically, and anatomically similar to human colonic epithelial neoplasm. Discrete microscopic mucosal lesions such as ACF and malignant tumors function as important biomarkers in the diagnosis of colon cancer. Methylene blue staining was carried out to visualize the impact of 1,2-dimethylhydrazine and myrtenal. Myrtenal-treated animals showed decreased levels of bacterial enzymes such as β-glucuronidase, β-glucosidase, and mucinase. Characteristic changes in the colon were noticed by inhibiting ACF formation in the colon. In conclusion, treatment with myrtenal provided altered pathophysiological condition in colon cancer-bearing animals with evidence of decreased crypt multiplicity and tumor progression.

Na/K-ATPase as a target for anticancer drugs: studies with perillyl alcohol

Background

Na/K-ATPase (NKA) is inhibited by perillyl alcohol (POH), a monoterpene used in the treatment of tumors, including brain tumors. The NKA α₁ subunit is known to be superexpressed in glioblastoma cells (GBM). This isoform is embedded in caveolar structures and is probably responsible for the signaling properties of NKA during apoptosis. In this work, we showed that POH acts in signaling cascades associated with NKA that control cell proliferation and/or cellular death.

Methods

NKA activity was measured by the amount of non-radioactive Rb⁺ incorporation into cultured GBM cell lines (U87 and U251) and non-tumor cells (mouse astrocytes and VERO cells). Cell viability was measured by lactate dehydrogenase levels in the supernatants of POH-treated cells. Activated c-Jun N-terminal Kinase (JNK) and p38 were assessed by western blotting. Apoptosis was detected by flow cytometry and immunocytochemistry, and the release of interleukins was measured by ELISA.

Results

All four cell types tested showed a similar sensitivity for POH. Perillic acid (PA), the main metabolite of POH, did not show any effect on these cells. Though the cell viability decreased in a dose-dependent manner when cells were treated with POH, the maximum cytotoxic effect of PA obtained was 30% at 4 mM. 1.5 mM POH activated p38 in U87 cells and JNK in both U87 and U251 cells as well as mouse astrocytes. Dasatinib (an inhibitor of the Src kinase family) and methyl β-cyclodextrin (which promotes cholesterol depletion in cell membranes) reduced the POH-induced activation of JNK1/2 in U87 cells, indicating that the NKA-Src complex participates in this mechanism. Inhibition of JNK1/2 by the JNK inhibitor V reduced the apoptosis of GBM cells that resulted from POH administration, indicating the involvement of JNK1/2 in programmed cell death. 1.5 mM POH increased the production of interleukin IL-8 in the U251 cell supernatant, which may indicate a possible strategy by which cells avoid the cytotoxic effects of POH.

Conclusions

A signaling mechanism mediated by NKA may have an important role in the anti-tumor action of POH in GBM cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0374-5) contains supplementary material, which is available to authorized users.

Antitumor activity of monoterpenes found in essential oils

Cancer is a complex genetic disease that is a major public health problem worldwide, accounting for about 7 million deaths each year. Many anticancer drugs currently used clinically have been isolated from plant species or are based on such substances. Accumulating data has revealed anticancer activity in plant-derived monoterpenes. In this review the antitumor activity of 37 monoterpenes found in essential oils is discussed. Chemical structures, experimental models, and mechanisms of action for bioactive substances are presented.

Perillyl Alcohol (Monoterpene Alcohol), Limonene

Natural products have a long history of use in traditional medicines and their activities against different diseases have been the focus of many basic and clinical researches in past few decades. The essential oils, volatile liquid containing aroma compound from plants, are known as active ingredients in the herbal medicine. Perillyl alcohol (POH) is usually available through dietary sources and is being explored for its cancer chemoprevention, tumor growth suppression, and regression. Citrus peels are the waste product of juice manufacturing industries and have been considered as a critical problem for environmental green ecology policies for years. One of the most well-known approaches to overcome this problem is transformation of these monoterpene by the use of specific strains of bacteria or yeasts. Limonene (1-methyl-4-isopropyl-cyclohexene) is a monoterpene, as other monoterpenes consists of two isoprene units, that comprises more than 90% of citrus essential oil and it exists in many fruits and vegetables. Although, the anticancer activity of d-limonene has identified nearly two decades ago, it has recently attracted much more attention in translational medicine. In this chapter, we will overview the anticancer effects of POH and d-limonene. Later, we will address the pharmacokinetics of these compounds, highlight the signaling pathways which are targeted by these proteins, review the clinical trials which have been done for these compounds in different cancer models, and finally discuss the future directions of the research in this field that might be more applicable in future cancer therapy strategies.

Multicomponent phytotherapeutic approach gaining momentum: Is the "one drug to fit all" model breaking down?

Natural product based drugs constitute a substantial proportion of the pharmaceutical market particularly in the therapeutic areas of infectious diseases and oncology. The primary focus of any drug development program so far has been to design selective ligands (drugs) that act on single selective disease targets to obtain highly efficacious and safe drugs with minimal side effects. Although this approach has been successful for many diseases, yet there is a significant decline in the number of new drug candidates being introduced into clinical practice over the past few decades. This serious innovation deficit that the pharmaceutical industries are facing is due primarily to the post-marketing failures of blockbuster drugs. Many analysts believe that the current capital-intensive model-"the one drug to fit all" approach will be unsustainable in future and that a new "less investment, more drugs" model is necessary for further scientific growth. It is now well established that many diseases are multi-factorial in nature and that cellular pathways operate more like webs than highways. There are often multiple ways or alternate routes that may be switched on in response to the inhibition of a specific target. This gives rise to the resistant cells or resistant organisms under the specific pressure of a targeted agent, resulting in drug resistance and clinical failure of the drug. Drugs designed to act against individual molecular targets cannot usually combat multifactorial diseases like cancer, or diseases that affect multiple tissues or cell types such as diabetes and immunoinflammatory diseases. Combination drugs that affect multiple targets simultaneously are better at controlling complex disease systems and are less prone to drug resistance. This multicomponent therapy forms the basis of phytotherapy or phytomedicine where the holistic therapeutic effect arises as a result of complex positive (synergistic) or negative (antagonistic) interactions between different components of a cocktail. In this approach, multicomponent therapy is considered to be advantageous for multifactorial diseases, instead of a "magic bullet" the metaphor of a "herbal shotgun" might better explain the state of affairs. The different interactions between various components might involve the protection of an active substance from decomposition by enzymes, modification of transport across membranes of cells or organelles, evasion of multidrug resistance mechanisms among others.

Disruption of the PI3K/AKT/mTOR signaling cascade and induction of apoptosis in HL-60 cells by an essential oil from Monarda citriodora

We have isolated an essential oil from Monarda citriodora (MC) and characterized its 22 chemical constituents with thymol (82%), carvacrol (4.82%), β-myrcene (3.45%), terpinen-4-ol (2.78%) and p-cymene (1.53%) representing the major constituents. We have reported for the first time the chemotherapeutic potential of MC in human promyelocytic leukemia HL-60 cells by means of apoptosis and disruption of the PI3K/AKT/mTOR signaling cascade. MC and its major constituent, thymol, inhibit the cell proliferation in different types of cancer cell lines like HL-60, MCF-7, PC-3, A-549 and MDAMB-231. MC was found to be more cytotoxic than thymol in HL-60 cells with an IC50 value of 22 μg/ml versus 45 μg/ml for thymol. Both MC and thymol induce apoptosis in HL-60 cells, which is evident by Hoechst staining, cell cycle analysis and immuno-expression of Bcl-xL, caspase-3,-8,-9 and PARP-1 cleavage. Both induce apoptosis by extrinsic and intrinsic apoptotic pathways that were confirmed by enhanced expression of death receptors (TNF-R1, Fas), caspase-9, loss of mitochondrial membrane potential and regression of Bcl-2/Bax ratio. Interestingly, both MC and thymol inhibit the downstream and upstream signaling of PI3K/AKT/mTOR pathway. The degree of apoptosis induction and disruption of the PI3K signaling cascade by MC was significantly higher when compared to thymol.

Myrtenal ameliorates diethylnitrosamine-induced hepatocarcinogenesis through the activation of tumor suppressor protein p53 and regulation of lysosomal and mitochondrial enzymes

Myrtenal is a novel class of compound belongs to monoterpenes found predominantly in mint, pepper, etc., and it was shown to have excellent pharmacological activities against many diseases among which cancer is imperative. Hepatocellular carcinoma is a primary malignancy of the hepatocytes, which rapidly leads to death in short periods. The aim of this study was to investigate the possible therapeutic efficiency of myrtenal against diethylnitrosamine-induced experimental hepatocarcinogenesis by analyzing the key enzymes of carbohydrate metabolism, lysosomal and mitochondrial TCA cycle enzymes, and also the possible role of tumor suppressor protein p53, and scanning electron microscopic studies. The results revealed that myrtenal significantly ameliorated the altered enzymes of carbohydrate metabolism, lysosomal and mitochondrial enzymes, and interestingly the tumor suppressor protein p53 was found to be significantly accumulated in myrtenal-treated animals, which inevitably confirms that myrtenal has a prominent role in preventing the liver cancer during treatment. Furthermore, the antineoplastic property was well evidenced by the mRNA expression of p53 protein by the reverse-transcriptase polymerase chain reaction and immunoblot analysis. The observed anticancer property of myrtenal may be due to the involvement and expression of p53 and influence in the mitochondrial and lysosomal membrane integrity and also interference in the gluconeogenesis process of cancer cells. Our results suggest that myrtenal is very efficient and useful compound in the treatment of liver cancer in future.

Targeting Ras-RAF-ERK and its interactive pathways as a novel therapy for malignant gliomas

Malignant gliomas are the most common and the deadliest brain malignancies in adults. Despite the lack of a complete understanding of the biology of these tumors, significant advances have been made in the past decades. One of the key discoveries made in the area of malignant gliomas is that these tumors can be induced and maintained by aberrant signaling networks. In this context, the Ras pathway has been extensively exploited, from both basic and translational perspectives. Although somatic oncogenic mutations of Ras genes are frequent in several cancer types, early investigations on gliomas revealed disappointing facts that the Ras mutations are nearly absent in malignant gliomas and that the BRAF mutations are present in a very small percentage of gliomas. Therefore, the observed deregulation of the Ras-RAF-ERK signaling pathway in gliomas is attributed to its upstream positive regulators, including, EGFR and PDGFR known to be highly active in the majority of malignant gliomas. In contrast to the initial negative results on the somatic mutations of H-Ras, K-Ras and BRAF, recent breakthrough studies on pediatric low-grade astrocytomas uncovered genetic alterations of the BRAF gene involving copy number gains and rearrangements. The 7q34 rearrangements result in a novel in-frame KIAA1549:BRAF fusion gene that possesses constitutive BRAF kinase activity resembling oncogenic BRAF (V600E). In light of the earlier findings and recent breakthroughs, this review summarizes our current understanding of the Ras-RAF-ERK signaling pathway in gliomas and the outcome of preclinical and clinical studies that evaluated the efficacy of Ras-targeted therapy in malignant gliomas.

Perillyl alcohol and methyl jasmonate sensitize cancer cells to cisplatin

Breast cancer is the second leading cause of cancer deaths among women in the United States. Several treatment options exist, with different side effects. To alleviate the side effects, several research groups have studied chemotherapeutic effects of plant compounds on cancer cells. These could be used as an alternative treatment option either alone or in combination with other chemotherapeutic drugs. The aim of this study was to evaluate the activity of a combination of perillyl alcohol (POH), methyl jasmonate (MJ) with cisplatin to define the most effective schedule and to investigate the mechanism of action in breast cancer cells. POH and MJ treatment (20% decrease in cell viability concentration) enhanced the cytotoxicity for subsequent exposure to cisplatin in MDA-MB-435 and MDA-MB-231 cells. Combination treatment of POH and MJ blocked cells at the G0/G1 phase of the cell cycle and the addition of cisplatin forced the cells to progress through the cell cycle and induced apoptosis. Apoptotic mechanistic studies indicated that POH and MJ treatment activated tumor necrosis factor receptor 1 and this was further increased by the addition of cisplatin. It was also found that mitochondrial membrane potential decreased with POH and MJ treatment; this effect was further enhanced by cisplatin treatment. These findings contributed to a better understanding of molecular mechanism of apoptosis in combination treatment of POH, MJ, and cisplatin. Results also showed that the combination treatment of three drugs is more effective than single drug alone or two drugs together.

Stereoselective synthesis of spiro and condensed pyrazolines of steroidal alpha,beta-unsaturated ketones and nitrilimines by 1,3-dipolar cycloaddition

Effective syntheses of endo- and exocyclic alpha,beta-unsaturated ketones as CC dipolarophiles were carried out in the 13alpha-estrone series. The 1,3-dipolar cycloadditions of 15,16alpha,beta-unsaturated ketones of 13alpha-estrone 3-methyl and 3-benzyl ether with nitrilimines stereoselectively furnished two regioisomers of new condensed pyrazolines in a ratio of 2:1. The main product was the isomer obtained by the attack of the N-terminus of the 1,3-dipole on the carbon atom beta to the carbonyl group of the dipolarophile. The nitrilimine cycloadditions to the 16-methylene-17-ketones of 13alpha-estrone 3-methyl and 3-benzyl ether stereo- and regioselectively furnished spiropyrazolines. The attack of the N-terminus of the dipole occurred on the alpha-carbon of the alpha,beta-unsaturated ketones. The reactions were performed under both homogeneous and heterogeneous conditions. Silver acetate as a base proved more effective than its triethylamine counterpart. Changes in regio- and stereoselectivities were not observed on variation of the conditions of the cycloaddition reactions. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI TOF MS techniques, with C(70) fullerenes as matrix in the latter case.

Phase II trial of daily oral perillyl alcohol (NSC 641066) in treatment-refractory metastatic breast cancer

PURPOSE

Perillyl alcohol (POH) is a naturally occurring lipid with preclinical activity against mammary carcinomas. We conducted a phase II multi-institutional study of oral POH administered four times daily in women with advanced treatment-refractory breast cancer.

METHODS

Eligible women were treated with POH four times daily at 1,200-1,500 mg m(-2) dose(-1) on a 28-day cycle. Patients tolerating 1,200 mg m(-2) day(-1) four times daily after one cycle were dose-escalated to 1,500 mg/m(2). The primary endpoint was 1-year freedom-from-progression (FFP) rate. Secondary endpoints were response rate, tolerability and correlative evaluations.

RESULTS

Twenty-nine cycles of POH were administered to 14 women. Three patients were dose-escalated to 1,500 mg/m(2). Grade 1 and grade 2 gastrointestinal effects and fatigue were predominant toxicities. Of seven patients receiving up to one cycle, three stopped therapy due to intolerance. Only two patients received more than two cycles, with disease stabilization of 3 and 8 months. Thirteen patients were evaluable for response. One-year FFP rate was zero. No objective responses were seen. The median time to progression was 35 days (95% CI, 29-123 days). Median overall survival was 389 days (95% CI, 202-776 days). Pharmacokinetic parameters were similar to previous investigations. The ability to correlate plasma TGF-beta1 levels with outcome was limited by lack of clinical benefit and inter- and intra-patient variability.

CONCLUSIONS

Enrollment was suspended short of planned accrual because of lack of response and poor tolerance to POH. This regimen does not appear to provide benefit in advanced treatment-refractory breast carcinoma.

Pharmaceutical and therapeutic Potentials of essential oils and their individual volatile constituents: a review

Essential oils and their volatile constituents are used widely to prevent and treat human disease. The possible role and mode of action of these natural products is discussed with regard to the prevention and treatment of cancer, cardiovascular diseases including atherosclerosis and thrombosis, as well as their bioactivity as antibacterial, antiviral, antioxidants and antidiabetic agents. Their application as natural skin penetration enhancers for transdermal drug delivery and the therapeutic properties of essential oils in aroma and massage therapy will also be outlined.

Anaplastic oligodendroglioma responding favorably to intranasal delivery of perillyl alcohol: a case report and literature review

BACKGROUND

In recent years, molecular genetics and biology are exerting significant influence on the practice of neuro-oncology, with oligodendrogliomas being the most prominent example. To explore therapeutic strategies and evaluate the clinical results, we report a case of a patient with anaplastic oligodendroglioma managed with intranasal delivery of POH.

CASE DESCRIPTION

A 62 year-old white woman presented with complaints of seizures and frontal headache in June 1999. Nervous system examination was normal. Her Karnofsky performance score was 90. A contrast-enhanced MRI scan of the brain revealed a regular space-occupying lesion in the right frontal lobe that enhanced with gadolinium. A radical surgical excision of the tumor was carried out, and the histopathological diagnosis was an anaplastic oligodendroglioma. Subsequently, there were 2 recurrent/progressive lesions, in July 2002 and October 2004, despite combination treatment using surgery, radiotherapy, and chemotherapy. Intranasal delivery of 0.3% concentration of POH 4 times daily was performed. A follow-up MRI scan after 5 months of treatment revealed reduction in size of the enhancing lesion.

CONCLUSION

Whereas surgery continues to be the primary treatment for oligodendroglioma, the scheme for postoperative therapy has shifted primarily because of the lesion's relative chemosensitivity. This article evaluates the effects of intranasal delivery of POH in a case of regression of anaplastic oligodendroglioma.

Chemoprevention of pancreatic cancer: a review of the molecular pathways involved, and evidence for the potential for chemoprevention

BACKGROUND

Pancreatic cancer has a poor prognosis. The use of drugs or natural agents which inhibit or slow down tumour growth therefore has important potential in the development of future therapies.

METHODS

A literature search of the PubMed and ISI Web of Science databases was undertaken to review the current data available on the alterations in signalling pathways found in pancreatic carcinogenesis, in order to identify sites that could be targeted by chemopreventive agents. Several agents of particular relevance to pancreatic cancer were identified, and their possible mechanisms of action reviewed.

RESULTS

Chemopreventive agents such as non-steroidal anti-inflammatory drugs, green tea constituents, and antioxidants have been shown to target various steps in intracellular signalling pathways, particularly those controlling cell proliferation and survival. Work on cell lines and animal models has shown that some of these agents may be able to modulate the growth of pancreatic tumours. Initial clinical trials of some chemopreventives in pancreatic cancer have been undertaken, and have yielded mixed results, prompting the need for further studies.

CONCLUSION

As the molecular pathology of pancreatic cancer becomes better understood, sites of action of chemopreventive substances have been uncovered. Several agents have shown promising results by their ability to inhibit pancreatic carcinogenesis in laboratory studies. If these effects can be successfully translated into human studies then these agents may prove to be valuable adjuvant therapies in the future.

Recent advances in the molecular genetics of malignant gliomas disclose targets for antitumor agent perillyl alcohol

Tumors of glial origin such as glioblastoma multiforme (GBM) comprise the majority of human brain tumors. Despite advances in surgery, radiation, and chemotherapy, the prognosis for patients with malignant glioma has not improved, emphasizing the need for a search for new chemotherapeutic drugs. Deregulated p21-Ras function, as a result of mutation, overexpression, or growth factor-induced overactivation, contributes to the growth of GBM. The monoterpene perillyl alcohol (POH) has preventive and therapeutic effects in a wide variety of preclinical tumor models and is currently under phase I and phase II clinical trials. As inhibition of posttranslational isoprenylation of Ras, a family of proteins that are involved in signal transduction is among the drug-related activities observed in this compound; POH may be a potential chemotherapeutic agent for GBM. Intranasal delivery is a practical and noninvasive approach that allows therapeutic agents that do not cross the blood-brain barrier to enter the central nervous system, reducing unwanted systemic side effects. This article describes the effect of intranasal delivery of POH in a patient with relapsed GBM.

Perillyl alcohol is an angiogenesis inhibitor

Aberrant angiogenesis is essential for the progression of solid tumors and hematological malignancies. Thus, antiangiogenic therapy is one of the most promising approaches to control cancer. In the present work, we examined the ability of perillyl alcohol (POH), a dietary monoterpene with well-established tumor chemopreventive and chemotherapeutic activity, to interfere with the process of angiogenesis. POH remarkably prevented new blood vessel growth in the in vivo chicken embryo chorioallantoic membrane assay and proved to be effective in inhibiting the morphogenic differentiation of cultured endothelial cells into capillary-like networks both in collagen gel and Matrigel models. In addition, POH reduced the cell number in a proliferation assay and induced apoptosis of endothelial cells as indicated by the POH-mediated increase of caspase-3 activity and DNA fragmentation. Consistent with the observed antisurvival effect, POH treatment resulted in a significant inhibition of Akt phosphorylation in endothelial cells. Finally, POH was able to differentially modulate the release of two important angiogenic regulators: vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2). POH decreased the release of VEGF from cancer cells but stimulated the expression of Ang2 by endothelial cells, indicating that it might suppress neovascularization and induce vessel regression. Overall, these data underscore the antiangiogenic potential of POH and suggest that POH, in addition to its anticancer activity, may be an effective agent in the treatment of angiogenesis-dependent diseases.