WIN55,212-2 induces cytoplasmic vacuolation in apoptosis-resistant MCL cells

Δ9-THC and CBD in Plasma, Oral Fluid, Exhaled Breath, and Urine from 23 Patients Administered Sativex

Background: Detecting the presence of Δ9-THC and CBD is mainly done through venous blood sampling, but other methods are becoming available. Oromucosal administration of Δ9-THC and CBD is less studied than inhalation, but this mode of administration is growing. In this study, we analyze samples obtained through invasive and noninvasive methods in a cohort of patients given oromucosally administered Δ9-THC and CBD to gain understanding in the strengths and weaknesses of the various detection methods. Materials and Methods: Blood, oral fluid (OF), exhaled breath, and urine were collected at several time points from 23 cannabis-naive patients after receiving a single dose of Sativex®; dose ranges: Δ9-THC, 2.7-18.9 mg; CBD 2.5-17.5 mg. Detection of Δ9-THC and CBD was done using liquid chromatography-mass spectrometry methods. Results: Δ9-THC and CBD were present in plasma, OF, and exhaled breath in all 23 patients. The detection time of Δ9-THC and CBD in OF and exhaled breath was longer than in blood. Urine analysis detected the Δ9-THC carboxy metabolite (THC-COOH) up to 7 days after administration, also in a patient who received 8.1/7.5 mg Δ9-THC/CBD. Conclusion: Time to detection of cannabinoids in blood samples was shorter than in exhaled breath and OF. Relative ease of sample collection combined with high sensitivity makes OF and exhaled breath specimens a valuable addition when samples are handled correctly. Δ9-THC metabolites were detected for an unexpected long period of time in urine. EudraCT Number: 2014-005553-39. Date of registration, December 29, 2015.

Paraptosis: a non-classical paradigm of cell death for cancer therapy

Due to the sustained proliferative potential of cancer cells, inducing cell death is a potential strategy for cancer therapy. Paraptosis is a mode of cell death characterized by endoplasmic reticulum (ER) and/or mitochondrial swelling and cytoplasmic vacuolization, which is less investigated. Considerable evidence shows that paraptosis can be triggered by various chemical compounds, particularly in cancer cells, thus highlighting the potential application of this non-classical mode of cell death in cancer therapy. Despite these findings, there remain significant gaps in our understanding of the role of paraptosis in cancer. In this review, we summarize the current knowledge on chemical compound-induced paraptosis. The ER and mitochondria are the two major responding organelles in chemical compound-induced paraptosis, which can be triggered by the reduction of protein degradation, disruption of sulfhydryl homeostasis, overload of mitochondrial Ca2+, and increased generation of reactive oxygen species. We also discuss the stumbling blocks to the development of this field and the direction for further research. The rational use of paraptosis might help us develop a new paradigm for cancer therapy.

Targeting GDP-Dissociation Inhibitor Beta (GDI2) with a Benzo[a]quinolizidine Library to Induce Paraptosis for Cancer Therapy

Inducing paraptosis, a nonapoptotic form of cell death, has great therapeutic potential in cancer therapy, especially for drug-resistant tumors. However, the specific molecular target(s) that trigger paraptosis have not yet been deciphered yet. Herein, by using activity-based protein profiling, we identified the GDP-dissociation inhibitor beta (GDI2) as a manipulable target for inducing paraptosis and uncovered benzo[a]quinolizidine BQZ-485 as a potent inhibitor of GDI2 through the interaction with Tyr245. Comprehensive target validation revealed that BQZ-485 disrupts the intrinsic GDI2-Rab1A interaction, thereby abolishing vesicular transport from the endoplasmic reticulum (ER) to the Golgi apparatus and initiating subsequent paraptosis events including ER dilation and fusion, ER stress, the unfolded protein response, and cytoplasmic vacuolization. Based on the structure of BQZ-485, we created a small benzo[a]quinolizidine library by click chemistry and discovered more potent GDI2 inhibitors using a NanoLuc-based screening platform. Leveraging the engagement of BQZ-485 with GDI2, we developed a selective GDI2 degrader. The optimized inhibitor (+)-37 and degrader 21 described in this study exhibited excellent in vivo antitumor activity in two GDI2-overexpressing pancreatic xenograft models, including an AsPc-1 solid tumor model and a transplanted human PDAC tumor model. Altogether, our findings provide a promising strategy for targeting GDI2 for paraptosis in the treatment of pancreatic cancers, and these lead compounds could be further optimized to be effective chemotherapeutics.

Influence of the Synthetic Cannabinoid Agonist on Normal and Inflamed Cartilage: An In Vitro Study

Medical marijuana (versus Marijuana derivatives) has been reported to possess analgesic, immunomodulatory, and anti-inflammatory properties. Recent studies in animal models of arthritis showed that cannabinoids, a group of compounds produced from marijuana, may attenuate joint damage. However, whether marijuana byproducts can suppress osteoarthritis (OA)-associated cartilage degradation has not been previously reported. In this study, human chondrocytes were isolated from healthy articular cartilage, expanded in vitro, and subjected to pellet culture in a chondrogenic medium to form cartilage tissues. We first examined the influence of marijuana byproducts on normal cartilage by treating chondrocyte-derived tissues with a synthetic cannabinoid agonist, Win-55,212-2 (Win), at different concentrations ranging from 0.01 to 10 µM. After treatment, the tissue phenotype was assessed using glycosaminoglycan (GAG) assay and real-time PCR. Next, cartilage tissues were pre-treated with interleukin-1β (IL-1β) to generate an inflamed phenotype and then cultured with Win to assess its therapeutic potential. The results showed that at concentrations lower than 1 µM, Win treatment did not significantly impair chondrocyte growth or cartilage formation capacity, but at a high level (>10 µM), it remarkably suppressed cell proliferation. Interestingly, under the condition of IL-1β pre-treatment, Win was able to partially preserve the cartilage matrix and decrease the production of interleukin-6, although the protective effect was mild. Taken together, our results indicated that the variable effects of Win on chondrocytes occur in a concentration-dependent manner. Whether cannabinoid derivatives can be used to treat cartilage degradation or can alter other structural changes in OA deserve further investigation.

Osimertinib induces paraptosis and TRIP13 confers resistance in glioblastoma cells

The efficacy of osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, has been evaluated in glioblastoma (GBM) through preclinical and clinical trials. However, the underlying mechanism of osimertinib-induced GBM cell death and the underlying resistance mechanism to osimertinib remains unclear. Here, we demonstrate that Osimertinib induces paraptosis in GBM cells, as evidenced by the formation of cytoplasmic vacuoles, accumulation of ubiquitinated proteins, and upregulation of endoplasmic reticulum (ER) stress markers like CHOP. Additionally, neither apoptosis nor autophagy was involved in the osimertinib-induced cell death. RNAseq analysis revealed ER stress was the most significantly downregulated pathway upon exposure to osimertinib. Consistently, pharmacologically targeting the PERK-eIF2α axis impaired osimertinib-induced paraptosis. Notably, we show that the expression of thyroid receptor-interacting protein 13 (TRIP13), an AAA+ATPase, alleviated osimertinib-triggered paraptosis, thus conferring resistance. Intriguingly, MK-2206, an AKT inhibitor, downregulated TRIP13 levels and synergized with Osimertinib to suppress TRIP13-induced high GBM cell growth in vitro and in vivo. Together, our findings reveal a novel mechanism of action associated with the anti-GBM effects of osimertinib involving ER stress-regulated paraptosis. Furthermore, we identify a TRIP13-driven resistance mechanism against Osimertinib in GBM and offer a combination strategy using MK-2206 to overcome such resistance.

Tetrahydrocannabinols: potential cannabimimetic agents for cancer therapy

Tetrahydrocannabinols (THCs) antagonize the CB1 and CB2 cannabinoid receptors, whose signaling to the endocannabinoid system is essential for controlling cell survival and proliferation as well as psychoactive effects. Most tumor cells express a much higher level of CB1 and CB2; THCs have been investigated as potential cancer therapeutic due to their cannabimimetic properties. To date, THCs have been prescribed as palliative medicine to cancer patients but not as an anticancer modality. Growing evidence of preclinical research demonstrates that THCs reduce tumor progression by stimulating apoptosis and autophagy and inhibiting two significant hallmarks of cancer pathogenesis: metastasis and angiogenesis. However, the degree of their anticancer effects depends on the origin of the tumor site, the expression of cannabinoid receptors on tumor cells, and the dosages and types of THC. This review summarizes the current state of knowledge on the molecular processes that THCs target for their anticancer effects. It also emphasizes the substantial knowledge gaps that should be of concern in future studies. We also discuss the therapeutic effects of THCs and the problems that will need to be addressed in the future. Clarifying unanswered queries is a prerequisite to translating the THCs into an effective anticancer regime.

2-Arachidonoylglycerol Modulates CXCL12-Mediated Chemotaxis in Mantle Cell Lymphoma and Chronic Lymphocytic Leukemia

To survive chemotherapy, lymphoma cells can relocate to protective niches where they receive support from the non-malignant cells. The biolipid 2-arachidonoylglycerol (2-AG), an agonist for the cannabinoid receptors CB1 and CB2, is released by stromal cells in the bone marrow. To investigate the role of 2-AG in lymphoma, we analyzed the chemotactic response of primary B-cell lymphoma cells enriched from peripheral blood of twenty-two chronic lymphocytic leukemia (CLL) and five mantle cell lymphoma (MCL) patients towards 2-AG alone and/or to the chemokine CXCL12. The expression of cannabinoid receptors was quantified using qPCR and the protein levels visualized by immunofluorescence and Western blot. Surface expression of CXCR4, the main cognate receptor to CXCL12, was analyzed by flow cytometry. Phosphorylation of key downstream signaling pathways activated by 2-AG and CXCL12 were measured by Western blot in three MCL cell lines and two primary CLL samples. We report that 2-AG induces chemotaxis in 80% of the primary samples, as well as 2/3 MCL cell lines. 2-AG induced in a dose-dependent manner, the migration of JeKo-1 cell line via CB1 and CB2. 2-AG affected the CXCL12-mediated chemotaxis without impacting the expression or internalization of CXCR4. We further show that 2-AG modulated p38 and p44/42 MAPK activation. Our results suggest that 2-AG has a previously unrecognized role in the mobilization of lymphoma cells by effecting the CXCL12-induced migration and the CXCR4 signaling pathways, however, with different effects in MCL compared to CLL.

Cannabidiol regulates apoptosis and autophagy in inflammation and cancer: A review

Cannabidiol (CBD) is a terpenoid naturally found in plants. The purified compound is used in the treatment of mental disorders because of its antidepressive, anxiolytic, and antiepileptic effects. CBD can affect the regulation of several pathophysiologic processes, including autophagy, cytokine secretion, apoptosis, and innate and adaptive immune responses. However, several authors have reported contradictory findings concerning the magnitude and direction of CBD-mediated effects. For example, CBD treatment can increase, decrease, or have no significant effect on autophagy and apoptosis. These variable results can be attributed to the differences in the biological models, cell types, and CBD concentration used in these studies. This review focuses on the mechanism of regulation of autophagy and apoptosis in inflammatory response and cancer by CBD. Further, we broadly elaborated on the prospects of using CBD as an anti-inflammatory agent and in cancer therapy in the future.

The Synthetic Cannabinoid WIN55,212-2 Can Disrupt the Golgi Apparatus Independent of Cannabinoid Receptor-1

The synthetic cannabinoid WIN55,212-2 (WIN) is widely used as a pharmacological tool to study the biologic activity of cannabinoid receptors. In contrast to many other cannabinoid agonists, however, WIN also causes broad effects outside of neurons, such as reducing inflammatory responses, causing cell cycle arrest, and reducing general protein expression. How exactly WIN causes these broad effects is not known. Here we show that WIN partially disrupts the Golgi apparatus at nanomolar concentrations and fully disperses the Golgi apparatus in neuronal and non-neuronal cells at micromolar concentrations. WIN55,212-3, the enantiomer of WIN; JWH-018, a related alkylindole; or 2-arachidonoylglycerol, an endocannabinoid, did not cause Golgi disruption, suggesting that the effect was specific to the chirality of WIN. WIN treatment also perturbed the microtubule network. Importantly, WIN disrupted the Golgi in primary cortical neurons derived from mice where cannabinoid receptor-1 (CB1) was genetically knocked out, indicating that the effects were independent of CB1 signaling. The Golgi dispersion could not be explained by WIN's action on peroxisome proliferator-activated receptors. Our results show that WIN can disrupt the Golgi apparatus independent of CB1 in cultured cells. These effects could contribute to the unique physiologic effects that WIN exhibits in neuronal behavior, as well as its role as an antiproliferative and anti-inflammatory agent. SIGNIFICANCE STATEMENT: The synthetic cannabinoid WIN55,212-2 (WIN), widely used to investigate the cannabinoid system, also shows unique broader effects at cellular and organismal levels compared to endogenous cannabinoids. Our study shows that WIN can disrupt the Golgi apparatus and the microtubule network in multiple cell types, independent of cannabinoid receptors. These results could explain how WIN reduces surface levels of proteins and contributes to the unique physiological effects observed with WIN.

The Isoxazole Derivative of Usnic Acid Induces an ER Stress Response in Breast Cancer Cells That Leads to Paraptosis-like Cell Death

Derivatives of usnic acid (UA), a secondary metabolite from lichens, were synthesized to improve its anticancer activity and selectivity. Recently we reported the synthesis and activity of an UA isoxazole derivative, named 2b, against cancer cells of different origins. Herein, the molecular mechanisms underlying its activity and efficacy in vivo were tested. The viability of breast cancer or normal cells has been tested using an MTT assay. Cell and organelle morphology was analyzed using light, electron and fluorescence microscopy. Gene expression was evaluated by RNAseq and protein levels were evaluated by Western blotting. In vivo anticancer activity was evaluated in a mice xenograft model. We found that 2b induced massive vacuolization which originated from the endoplasmic reticulum (ER). ER stress markers were upregulated both at the mRNA and protein levels. ER stress was caused by the release of Ca²⁺ ions from the ER by IP3R channels which was mediated, at least partly, by phospholipase C (PLC)-synthetized 1,4,5-inositol triphosphate (IP3). ER stress led to cell death with features of apoptosis and paraptosis. When applied to nude mice with xenografted breast cancer cells, 2b stopped tumour growth. In mice treated with 2b, vacuolization was observed in tumour cells, but not in other organs. This study shows that the antiproliferative activity of 2b relates to the induction of ER stress in cancer, not in healthy, cells and it leads to breast cancer cell death in vitro and in vivo.

Cannabis with breast cancer treatment: propitious or pernicious?

Cannabis has been used for various medicinal applications including, but not limited to, cancer: most commonly to treat chemotherapy-associated side effects. Cannabis is often used for its palliative effects in the form of purified cannabinoids, or as extracts. This study was conducted using two breast cancer cell lines and aimed to evaluate potential anti-proliferative "intra-entourage effects" between purified phytocannabinoids resembling the THC and CBD ratios of medicinal and recreational cannabis strains, as well as to investigate potential "inter-entourage effects" between the different ratios and the phytochemicals found in a Cannabis sativa extract. This study also aimed to evaluate the potential interaction between cannabinoids and chemotherapeutic agents. The data identified an intra-entourage effect present in the MCF-7 cells when treated with a recreational, but not a medicinal, cannabis formulation. This effect may be due to THC partially exerting its anti-proliferative effects through the estrogen receptor (ER), present in the MCF-7 cell line. Little to no intra-entourage effects were observed in the MDA-MB-231 cell line and no inter-entourage effects were observed in either cell line. The simultaneous treatment of the MCF-7 cell line with various cannabinoid formulations and the common breast cancer treatment, tamoxifen, resulted in the diminished anti-proliferative activity of tamoxifen, an effect that was more evident when combined with recreational cannabis formulations. Since cannabis is commonly used in palliative care to treat chemotherapy-associated side effects, further research is required to investigate the potential interference of various cannabis formulations to ensure that the efficacy of chemotherapeutic agents is not compromised.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03102-1.

Clinical effects of a single dose of cannabinoids to patients with chronic lymphocytic leukemia

This phase II clinical trial investigates a one-time oromucosal dose of tetrahydrocannabinol/cannabidiol (THC/CBD) in 23 patients with indolent leukemic B cell lymphomas. Primary endpoint was a significant reduction in leukemic B cells. Grade 1 - 2 adverse events were seen in 91% of the patients; most common were dry mouth (78%), vertigo (70%), and somnolence (43%). After THC/CBD a significant reduction in leukemic B cells (median, 11%) occurred within two hours (p = .014), and remained for 6 h without induction of apoptosis or proliferation. Normal B cells and T cells were also reduced. CXCR4 expression increased on leukemic cells and T cells. All effects were gone by 24 h. Our results show that a single dose of THC/CBD affects a wide variety of leukocytes and only transiently reduce malignant cells in blood. Based on this study, THC/CBD shows no therapeutic potential for indolent B cell lymphomas (EudraCT trial no. 2014-005553-39).

The Interplay between the Immune and the Endocannabinoid Systems in Cancer

The therapeutic potential of Cannabis sativa has been recognized since ancient times. Phytocannabinoids, endocannabinoids and synthetic cannabinoids activate two major G protein-coupled receptors, subtype 1 and 2 (CB1 and CB2). Cannabinoids (CBs) modulate several aspects of cancer cells, such as apoptosis, autophagy, proliferation, migration, epithelial-to-mesenchymal transition and stemness. Moreover, agonists of CB1 and CB2 receptors inhibit angiogenesis and lymphangiogenesis in vitro and in vivo. Low-grade inflammation is a hallmark of cancer in the tumor microenvironment (TME), which contains a plethora of innate and adaptive immune cells. These cells play a central role in tumor initiation and growth and the formation of metastasis. CB2 and, to a lesser extent, CB1 receptors are expressed on a variety of immune cells present in TME (e.g., T cells, macrophages, mast cells, neutrophils, NK cells, dendritic cells, monocytes, eosinophils). The activation of CB receptors modulates a variety of biological effects on cells of the adaptive and innate immune system. The expression of CB2 and CB1 on different subsets of immune cells in TME and hence in tumor development is incompletely characterized. The recent characterization of the human cannabinoid receptor CB2-G_i signaling complex will likely aid to design potent and specific CB2/CB1 ligands with therapeutic potential in cancer.

Cannabinoid Combination Induces Cytoplasmic Vacuolation in MCF-7 Breast Cancer Cells

This study evaluated the synergistic anti-cancer potential of cannabinoid combinations across the MDA-MB-231 and MCF-7 human breast cancer cell lines. Cannabinoids were combined and their synergistic interactions were evaluated using median effect analysis. The most promising cannabinoid combination (C6) consisted of tetrahydrocannabinol, cannabigerol (CBG), cannabinol (CBN), and cannabidiol (CBD), and displayed favorable dose reduction indices and limited cytotoxicity against the non-cancerous breast cell line, MCF-10A. C6 exerted its effects in the MCF-7 cell line by inducing cell cycle arrest in the G₂ phase, followed by the induction of apoptosis. Morphological observations indicated the induction of cytoplasmic vacuolation, with further investigation suggesting that the vacuole membrane was derived from the endoplasmic reticulum. In addition, lipid accumulation, increased lysosome size, and significant increases in the endoplasmic reticulum chaperone protein glucose-regulated protein 78 (GRP78) expression were also observed. The selectivity and ability of cannabinoids to halt cancer cell proliferation via pathways resembling apoptosis, autophagy, and paraptosis shows promise for cannabinoid use in standardized breast cancer treatment.

Cannabinoids as anticancer therapeutic agents

The recent announcement of marijuana legalization in Canada spiked many discussions about potential health benefits of Cannabis sativa. Cannabinoids are active chemical compounds produced by cannabis, and their numerous effects on the human body are primarily exerted through interactions with cannabinoid receptor types 1 (CB1) and 2 (CB2). Cannabinoids are broadly classified as endo-, phyto-, and synthetic cannabinoids. In this review, we will describe the activity of cannabinoids on the cellular level, comprehensively summarize the activity of all groups of cannabinoids on various cancers and propose several potential mechanisms of action of cannabinoids on cancer cells.

Ginger extract activates caspase independent paraptosis in cancer cells via ER stress, mitochondrial dysfunction, AIF translocation and DNA damage

The rhizome of ginger (Zingiber officinale) a common culinary agent is also known for its medicinal activity. We have earlier reported that pure 6-shogaol, an important component of ginger induces paraptosis in triple negative breast cancer (MDA-MB-231) and non small cell lung (A549) cancer cells. However, the chemopreventive potential of the whole ginger extract in food remains to be elucidated. Here, we demonstrate for the first time that ginger extract (GE) triggers similar anticancer activity/paraptosis against the same cell lines but through different molecular mechanisms. Q-TOF LC-MS analysis of the extract showed the presence of several other metabolites along with 6-shogaol and 6-gingerol. GE induces cytoplasmic vacuolation through ER stress and dilation of the ER. Drastic decrease in the mitochondrial membrane potential and ATP production along with the excess generation of ROS contributed to mitochondrial dysfunction. Consequently, GE caused the translocation of apoptosis inducing factor to the nucleus leading to the fragmentation of DNA. Taken together, these show a novel mechanism for ginger extract induced cancer cell death that can be of potential interest for cancer preventive strategies.

Curcuminoid B63 induces ROS-mediated paraptosis-like cell death by targeting TrxR1 in gastric cells

Gastric cancer is one of the leading causes of cancer-related deaths. Chemotherapy has improved long-term survival of patients with gastric cancer. Unfortunately, cancer readily develops resistance to apoptosis-inducing agents. New mechanisms, inducing caspase-independent paraptosis-like cell death in cancer cells is presently emerging as a potential direction. We previously developed a curcumin analog B63 as an anti-cancer agent in pre-clinical evaluation. In the present study, we evaluated the effect and mechanism of B63 on gastric cancer cells. Our studies show that B63 targets TrxR1 protein and increases cellular reactive oxygen species (ROS) level, which results in halting gastric cancer cells and inducing caspase-independent paraptotic modes of death. The paraptosis induced by B63 was mediated by ROS-mediated ER stress and MAPK activation. Either overexpression of TrxR1 or suppression of ROS normalized B63-induced paraptosis in gastric cancer cells. Furthermore, B63 caused paraptosis in 5-fluorouracil-resistant gastric cancer cells, and B63 treatment reduced the growth of gastric cancer xenografts, which was associated with increased ROS and paraptosis. Collectively, our findings provide a novel strategy for the treatment of gastric cancer by utilizing TrxR1-mediated oxidative stress generation and subsequent cell paraptosis.

Chalcomoracin is a potent anticancer agent acting through triggering Oxidative stress via a mitophagy- and paraptosis-dependent mechanism

Chalocomoracin (CMR), one of the major secondary metabolites found in fungus-infected mulberry leaves, is a potent anticancer agent. However, its anticancer mechanism remains elusive. Here, we demonstrated the potent anti-tumor activity and molecular mechanism of CMR both in vitro and in vivo. We showed for the first time that CMR treatment markedly promoted paraptosis along with extensive cytoplasmic vacuolation derived from the endoplasmic reticulum, rather than apoptosis, in PC-3 and MDA-MB-231cell lines. Additional studies revealed that ectopic expression of Myc-PINK1 (PTEN-induced kinase 1), a key regulator of mitophagy, rendered LNCap cells susceptible to CMR-induced paraptosis, suggesting that the mitophagy-dependent pathway plays a crucial role in inducing paraptosis by activating PINK1. CMR treatment directly upregulated PINK1 and downregulated Alix genes in MDA-MB-231 and PC-3 cell lines. Furthermore, mitophagy signaling and paraptosis with cytoplasmic vacuolation could be blocked by antioxidant N-acetylcysteine (NAC), indicating the novel pathway was triggered by reactive oxygen species (ROS) production. An in vivo MDA-MB-231 xenograft tumor model revealed that CMR suppressed tumor growth by inducing vacuolation production through the same signal changes as those observed in vitro. These data suggest that CMR is a potential therapeutic entity for cancer treatment through a non-apoptotic pathway.

The tamoxifen derivative ridaifen-B is a high affinity selective CB2 receptor inverse agonist exhibiting anti-inflammatory and anti-osteoclastogenic effects

Selective estrogen receptor modulators (SERMs) target estrogen receptors (ERs) to treat breast cancer and osteoporosis. Several SERMs exhibit anti-cancer activity not related to ERs. To discover novel anti-cancer drugs acting via ER-independent mechanisms, derivatives of the SERM tamoxifen, known as the "ridaifen" compounds, have been developed that exhibit reduced or no ER affinity, while maintaining cytotoxicity. Tamoxifen and other SERMs bind to cannabinoid receptors with moderate affinity. Therefore, ER-independent effects of SERMs might be mediated via cannabinoid receptors. This study determined whether RID-B, a first generation ridaifen compound, exhibits affinity and/or activity at CB₁ and/or CB₂ cannabinoid receptors. RID-B binds with high affinity (K_i = 43.7 nM) and 17-fold selectivity to CB₂ over CB₁ receptors. RID-B acts as an inverse agonist at CB₂ receptors, modulating G-protein and adenylyl cyclase activity with potency values predicted by CB₂ affinity. Characteristic of an antagonist, RID-B co-incubation produces a parallel-rightward shift in the concentration-effect curve of CB₂ agonist WIN-55,212-2 to inhibit adenylyl cyclase activity. CB₂ inverse agonists are reported to exhibit anti-inflammatory and anti-ostoeclastogenic effects. In LPS-activated macrophages, RID-B exhibits anti-inflammatory effects by reducing levels of nitric oxide (NO), IL-6 and IL-1α, but not TNFα. Only reduction of NO concentration by RID-B is mediated by cannabinoid receptors. RID-B also exhibits pronounced anti-osteoclastogenic effects, reducing the number of osteoclasts differentiating from primary bone marrow macrophages in a cannabinoid receptor-dependent manner. In summary, the tamoxifen derivative RID-B, developed with reduced affinity for ERs, is a high affinity selective CB₂ inverse agonist with anti-inflammatory and anti-osteoclastogenic properties.

Xanthohumol induces paraptosis of leukemia cells through p38 mitogen activated protein kinase signaling pathway

Xanthohumol as a natural polyphenol demonstrates an anticancer activity, but its underlying mechanism remains unclear. In this study, we showed that xanthohumol (XN) induces paraptosis of leukemia cells. The paraptosis is one cell death which is characterized by dilation of the endoplasmic reticulum and/or mitochondria. The results demonstrated that XN treatment significantly inhibited cell proliferation and triggered extensive cytoplasmic vacuolation of HL-60 leukemia cells, but it did not cause the cleavage of caspase-3 protein or apoptosis. In contrast, XN treatment resulted in LC3-II accumulation through blocking of autophagosome maturation. Interestingly, the induction of cytoplasmic vacuolization by XN is not associated with autophagy modulated by XN, therefore, XN-induced cell death of HL-60 leukemia cells is not the classical apoptotic cell death. Intriguingly, XN treatment triggered the dilatation of endoplasma reticulum (ER) and induced ER stress by upregulating C/EBP homologous protein and unfolded protein response regulator Grp78/Bip. Furthermore, XN treatment triggered p38 mitogen activated protein kinase and its specific inhibitor inhibited the paraptosis of HL-60 leukemia cells by XN. In conclusion, we for the first time demonstrated that XN treatment can induce paraptosis of leukemia cells through activation of p38 MAPK signaling.

6-Shogaol induces caspase-independent paraptosis in cancer cells via proteasomal inhibition

An α, β-unsaturated carbonyl compound of ginger, 6-Shogaol (6S), induced extensive cytoplasmic vacuolation and cell death in breast cancer cell (MDA-MB-231) and non-small lung cancer (A549) cells. In the presence of autophagic inhibitors the cells continued to exhibit cytoplasmic vacuolation and cell death clearly distinguishing it from the classic autophagic process. 6S induced death did not exhibit the characteristic apoptotic features like caspase cleavage, phosphatidyl serine exposure and DNA fragmentation. The immunofluorescence with the Endoplasmic Reticulum (ER) resident protein, calreticulin indicated that the vacuoles were of ER origin, typical of paraptosis. This was supported by the increase in level of microtubule associated protein light chain 3B (LC3 I and LC3 II) and polyubiquitin binding protein, p62. The level of ER stress markers like polyubiquitinated proteins, Bip and CHOP also consistently increased. We have found that 6S inhibits the 26S proteasome. The proteasomal inhibitory activity was elucidated by a) molecular docking of 6S onto the active site of β5 subunit and b) reduced fluorescence by the fluorogenic substrate of the chymotrypsin-like subunit. In conclusion these studies demonstrate for the first time that proteasomal inhibition by 6S induces cell death via paraptosis. So 6-shogaol may act as a template for anti-cancer lead discovery against the apoptosis resistant cancer cells.

Cytoplasmic vacuolization in cell death and survival

Cytoplasmic vacuolization (also called cytoplasmic vacuolation) is a well-known morphological phenomenon observed in mammalian cells after exposure to bacterial or viral pathogens as well as to various natural and artificial low-molecular-weight compounds. Vacuolization often accompanies cell death; however, its role in cell death processes remains unclear. This can be attributed to studying vacuolization at the level of morphology for many years. At the same time, new data on the molecular mechanisms of the vacuole formation and structure have become available. In addition, numerous examples of the association between vacuolization and previously unknown cell death types have been reported. Here, we review these data to make a deeper insight into the role of cytoplasmic vacuolization in cell death and survival.

Gypenoside L inhibits autophagic flux and induces cell death in human esophageal cancer cells through endoplasm reticulum stress-mediated Ca2+ release

Esophageal cancer is one of the leading cause of cancer mortality in the world. Due to the increased drug and radiation tolerance, it is urgent to develop novel anticancer agent that triggers nonapoptotic cell death to compensate for apoptosis resistance. In this study, we show that treatment with gypenoside L (Gyp-L), a saponin isolated from Gynostemma pentaphyllum, induced nonapoptotic, lysosome-associated cell death in human esophageal cancer cells. Gyp-L-induced cell death was associated with lysosomal swelling and autophagic flux inhibition. Mechanistic investigations revealed that through increasing the levels of intracellular reactive oxygen species (ROS), Gyp-L triggered protein ubiquitination and endoplasm reticulum (ER) stress response, leading to Ca2+ release from ER inositol trisphosphate receptor (IP3R)-operated stores and finally cell death. Interestingly, there existed a reciprocal positive-regulatory loop between Ca2+ release and ER stress in response to Gyp-L. In addition, protein synthesis was critical for Gyp-L-mediated ER stress and cell death. Taken together, this work suggested a novel therapeutic option by Gyp-L through the induction of an unconventional ROS-ER-Ca2+-mediated cell death in human esophageal cancer.

Cannabinoids Modulate Neuronal Activity and Cancer by CB1 and CB2 Receptor-Independent Mechanisms

Cannabinoids include the active constituents of Cannabis or are molecules that mimic the structure and/or function of these Cannabis-derived molecules. Cannabinoids produce many of their cellular and organ system effects by interacting with the well-characterized CB1 and CB2 receptors. However, it has become clear that not all effects of cannabinoid drugs are attributable to their interaction with CB1 and CB2 receptors. Evidence now demonstrates that cannabinoid agents produce effects by modulating activity of the entire array of cellular macromolecules targeted by other drug classes, including: other receptor types; ion channels; transporters; enzymes, and protein- and non-protein cellular structures. This review summarizes evidence for these interactions in the CNS and in cancer, and is organized according to the cellular targets involved. The CNS represents a well-studied area and cancer is emerging in terms of understanding mechanisms by which cannabinoids modulate their activity. Considering the CNS and cancer together allow identification of non-cannabinoid receptor targets that are shared and divergent in both systems. This comparative approach allows the identified targets to be compared and contrasted, suggesting potential new areas of investigation. It also provides insight into the diverse sources of efficacy employed by this interesting class of drugs. Obtaining a comprehensive understanding of the diverse mechanisms of cannabinoid action may lead to the design and development of therapeutic agents with greater efficacy and specificity for their cellular targets.

Phytoagent deoxyelephantopin derivative inhibits triple negative breast cancer cell activity by inducing oxidative stress-mediated paraptosis-like cell death

Triple negative breast cancer (TNBC) is a highly metastatic cancer among the breast cancer subgroups. A thorny issue for clinical therapy of TNBC is lack of an efficient targeted therapeutic strategy. We previously created a novel sesquiterpene lactone analog (named DETD-35) derived from plant deoxyelephantopin (DET) which exhibits potent effects against human TNBC MDA-MB-231 tumor growth in a xenograft mouse model. Here we studied the mechanisms of both DET and DETD-35 against MDA-MB-231 cells. DETD-35 (3-fold decreased in IC50) exhibited better anti-TNBC cell activity than DET as observed through induction of reactive oxygen species production (within 2 h treatment) and damage to the ER structures, resulting in ER-derived cytoplasmic vacuolation and ubiquitinated protein accumulation in the treated cells. Intriguingly, the effects of both compounds were blockaded by pretreatment with ROS scavengers, N-acetylcysteine and reduced glutathione, and protein synthesis inhibitor, cycloheximide. Further, knockdown of MEK upstream regulator RAF1 and autophagosomal marker LC3, and co-treatment with JNK or ERK1/2 inhibitor resulted in the most significant attenuation of DETD-35-induced morphological and molecular or biochemical changes in cancer cells, while the inhibitory effect of DET was not influenced by MAPK inhibitor treatment. Therefore, DETD-35 exerted both ER stress-mediated paraptosis and apoptosis, which may explain its superior activity to DET against TNBC cells. Although the chemotherapeutic drug paclitaxel induced vacuole-like structures in MDA-MB-231 cells, no paraptotic cell death features were detected. This study provides a strategy for combating TNBC through sesquiterpene lactone analogs by induction of oxidative and ER stresses that cause paraptosis-like cell death.

The role of G protein-coupled receptors in lymphoid malignancies

B cell lymphoma consists of multiple individual diseases arising throughout the lifespan of B cell development. From pro-B cells in the bone marrow, through circulating mature memory B cells, each stage of B cell development is prone to oncogenic mutation and transformation, which can lead to a corresponding lymphoma. Therapies designed against individual types of lymphoma often target features that differ between malignant cells and the corresponding normal cells from which they arise. These genetic changes between tumor and normal cells can include oncogene activation, tumor suppressor gene repression and modified cell surface receptor expression. G protein-coupled receptors (GPCRs) are an important class of cell surface receptors that represent an ideal target for lymphoma therapeutics. GPCRs bind a wide range of ligands to relay extracellular signals through G protein-mediated signaling cascades. Each lymphoma subgroup expresses a unique pattern of GPCRs and efforts are underway to fully characterize these patterns at the genetic level. Aberrations such as overexpression, deletion and mutation of GPCRs have been characterized as having causative roles in lymphoma and such studies describing GPCRs in B cell lymphomas are summarized here.

Jaspine B induces nonapoptotic cell death in gastric cancer cells independently of its inhibition of ceramide synthase

Sphingolipids (SLs) have been extensively investigated in biomedical research due to their role as bioactive molecules in cells. Here, we describe the effect of a SL analog, jaspine B (JB), a cyclic anhydrophytosphingosine found in marine sponges, on the gastric cancer cell line, HGC-27. JB induced alterations in the sphingolipidome, mainly the accumulation of dihydrosphingosine, sphingosine, and their phosphorylated forms due to inhibition of ceramide synthases. Moreover, JB provoked atypical cell death in HGC-27 cells, characterized by the formation of cytoplasmic vacuoles in a time and dose-dependent manner. Vacuoles appeared to originate from macropinocytosis and triggered cytoplasmic disruption. The pan-caspase inhibitor, z-VAD, did not alter either cytotoxicity or vacuole formation, suggesting that JB activates a caspase-independent cell death mechanism. The autophagy inhibitor, wortmannin, did not decrease JB-stimulated LC3-II accumulation. In addition, cell vacuolation induced by JB was characterized by single-membrane vacuoles, which are different from double-membrane autophagosomes. These findings suggest that JB-induced cell vacuolation is not related to autophagy and it is also independent of its action on SL metabolism.

Anticancer potential of Thevetia peruviana fruit methanolic extract

BACKGROUND

Thevetia peruviana (Pers.) K. Schum or Cascabela peruviana (L.) Lippold (commonly known as ayoyote, codo de fraile, lucky nut, or yellow oleander), native to Mexico and Central America, is a medicinal plant used traditionally to cure diseases like ulcers, scabies, hemorrhoids and dissolve tumors. The purpose of this study was to evaluate the cytotoxic, antiproliferative and apoptotic activity of methanolic extract of T. peruviana fruits on human cancer cell lines.

METHODS

The cytotoxic activity of T. peruviana methanolic extract was carried out on human breast, colorectal, prostate and lung cancer cell lines and non-tumorigenic control cells (fibroblast and Vero), using the MTT assay. For proliferation and motility, clonogenic and wound-healing assays were performed. Morphological alterations were monitored by trypan blue exclusion, as well as DNA fragmentation and AO/EB double staining was performed to evaluate apoptosis. The extract was separated using flash chromatography, and the resulting fractions were evaluated on colorectal cancer cells for their cytotoxic activity. The active fractions were further analyzed through mass spectrometry.

RESULTS

The T. peruviana methanolic extract exhibited cytotoxic activity on four human cancer cell lines: prostate, breast, colorectal and lung, with values of IC₅₀ 1.91 ± 0.76, 5.78 ± 2.12, 6.30 ± 4.45 and 12.04 ± 3.43 μg/mL, respectively. The extract caused a significant reduction of cell motility and colony formation on all evaluated cancer cell lines. In addition, morphological examination displayed cell size reduction, membrane blebbing and detachment of cells, compared to non-treated cancer cell lines. The T. peruviana extract induced apoptotic cell death, which was confirmed by DNA fragmentation and AO/EB double staining. Fractions 4 and 5 showed the most effective cytotoxic activity and their MS analysis revealed the presence of the secondary metabolites: thevetiaflavone and cardiac glycosides.

CONCLUSION

T. peruviana extract has potential as natural anti-cancer product with critical effects in the proliferation, motility, and adhesion of human breast and colorectal cancer cells, and apoptosis induction in human prostate and lung cancer cell lines, with minimal effects on non-tumorigenic cell lines.

Apoptosis-independent organoruthenium anticancer complexes that overcome multidrug resistance: self-assembly and phenotypic screening strategies

Multidrug resistance is a major impediment to chemotherapy and limits the efficacies of conventional anticancer drugs. A strategy to bypass multidrug resistance is to develop new drug candidates capable of inducing apoptosis-independent programmed cell death. However, cellular pathways implicated in alternative programmed cell death are not well-elucidated and multifactorial, making a target-based discovery approach a challenge. Here, we show that a coordination-directed three-component assembly and phenotypic screening strategy could be employed as a viable alternative for the identification of apoptosis-independent organoruthenium anticancer agents. Through an on-plate synthesis and screening of 195 organoruthenium complexes against apoptosis-sensitive and -resistant cancers, we identified two apoptosis-independent hits. Subsequent validation of the two hits showed a lack of induction of apoptotic biomarkers, a caspase-independent activity and an equal efficacy in both apoptosis-sensitive and -resistant colorectal cancers. This validated their apoptosis-independent modes-of-action, paving the way as potential candidates for the treatment of highly-refractory cancer phenotypes.

SNIPER(TACC3) induces cytoplasmic vacuolization and sensitizes cancer cells to Bortezomib

We previously developed a hybrid small molecule SNIPER (Specific and Nongenetic IAP‐dependent Protein ERaser) against transforming acidic coiled‐coil‐3 (TACC3), SNIPER(TACC3), that induces proteasomal degradation of TACC3 protein. In this study, we found that SNIPER(TACC3) induces cytoplasmic vacuolization derived from endoplasmic reticulum (ER) and paraptosis‐like cell death selectively in cancer cells. Mechanistic analysis suggests that accumulation of ubiquitylated protein aggregates that requires X‐linked inhibitor of apoptosis protein (XIAP) induces ER stress, which results in ER‐stress responses involving X‐box binding protein‐1 (XBP‐1) and ER‐derived vacuolization in cancer cells. Importantly, inhibition of proteasome enhanced the SNIPER(TACC3)‐induced vacuolization, and the combination treatment of SNIPER(TACC3) and bortezomib exhibited a synergistic anticancer activity in several cancer cell lines. The induction of paraptosis‐like cell death in cancer cells by SNIPER(TACC3) could be applied to treat cancer cells resistant to undergo apoptosis by overexpression of XIAP.

Macrolide Antibiotics Exhibit Cytotoxic Effect under Amino Acid-Depleted Culture Condition by Blocking Autophagy Flux in Head and Neck Squamous Cell Carcinoma Cell Lines

Autophagy, a self-digestive system for cytoplasmic components, is required to maintain the amino acid pool for cellular homeostasis. We previously reported that the macrolide antibiotics azithromycin (AZM) and clarithromycin (CAM) have an inhibitory effect on autophagy flux, and they potently enhance the cytocidal effect of various anticancer reagents in vitro. This suggests that macrolide antibiotics can be used as an adjuvant for cancer chemotherapy. Since cancer cells require a larger metabolic demand than normal cells because of their exuberant growth, upregulated autophagy in tumor cells has now become the target for cancer therapy. In the present study, we examined whether macrolides exhibit cytotoxic effect under an amino acid-starving condition in head and neck squamous cancer cell lines such as CAL 27 and Detroit 562 as models of solid tumors with an upregulated autophagy in the central region owing to hypovascularity. AZM and CAM induced cell death under the amino acid-depleted (AAD) culture condition in these cell lines along with CHOP upregulation, although they showed no cytotoxicity under the complete culture medium. CHOP knockdown by siRNA in the CAL 27 cells significantly suppressed macrolide-induced cell death under the AAD culture condition. CHOP-/- murine embryonic fibroblast (MEF) cell lines also attenuated AZM-induced cell death compared with CHOP+/+ MEF cell lines. Using a tet-off atg5 MEF cell line, knockout of atg5, an essential gene for autophagy, also induced cell death and CHOP in the AAD culture medium but not in the complete culture medium. This suggest that macrolide-induced cell death via CHOP induction is dependent on autophagy inhibition. The cytotoxicity of macrolide with CHOP induction was completely cancelled by the addition of amino acids in the culture medium, indicating that the cytotoxicity is due to the insufficient amino acid pool. These data suggest the possibility of using macrolides for "tumor-starving therapy".

Non-canonical programmed cell death mechanisms triggered by natural compounds

Natural compounds are the fundament of pharmacological treatments and more than 50% of all anticancer drugs are of natural origins or at least derived from scaffolds present in Nature. Over the last 25 years, molecular mechanisms triggered by natural anticancer compounds were investigated. Emerging research showed that molecules of natural origins are useful for both preventive and therapeutic purposes by targeting essential hallmarks and enabling characteristics described by Hanahan and Weinberg. Moreover, natural compounds were able to change the differentiation status of selected cell types. One of the earliest response of cells treated by pharmacologically active compounds is the change of its morphology leading to ultra-structural perturbations: changes in membrane composition, cytoskeleton integrity, alterations of the endoplasmic reticulum, mitochondria and of the nucleus lead to formation of morphological alterations that are a characteristic of both compound and cancer type preceding cell death. Apoptosis and autophagy were traditionally considered as the most prominent cell death or cell death-related mechanisms. By now multiple other cell death modalities were described and most likely involved in response to chemotherapeutic treatment. It can be hypothesized that especially necrosis-related phenotypes triggered by various treatments or evolving from apoptotic or autophagic mechanisms, provide a more efficient therapeutic outcome depending on cancer type and genetic phenotype of the patient. In fact, the recent discovery of multiple regulated forms of necrosis and the initial elucidation of the corresponding cell signaling pathways appear nowadays as important tools to clarify the immunogenic potential of non-canonical forms of cell death induction.

Novel Benzo[a]quinolizidine Analogs Induce Cancer Cell Death through Paraptosis and Apoptosis

Paraptosis is nonapoptotic cell death characterized by massive endoplasmic reticulum (ER)- or mitochondria-derived vacuoles. Induction of paraptosis offers significant advantages for the treatment of chemotherapy-resistant tumors compared with anticancer drugs that rely on apoptosis. Because some natural alkaloids induce paraptotic cell death, a novel series of benzo[a]quinolizidine derivatives were synthesized, and their antiproliferative activity and ability to induce cytoplasmic vacuolation were analyzed. Structural optimization led to the identification of the potent compound 22b, which inhibited cancer cell proliferation in vitro and in vivo and profoundly facilitated paraptosis-like cell death and induced caspase-dependent apoptosis. Further investigation revealed that 22b-mediated vacuolation originated from persistent ER stress and upregulation of LC3B. Paraptosis induced by benzo[a]quinolizidine derivatives thus represents an alternative strategy for cancer chemotherapy.

The synthetic cannabinoid WIN55,212-2 mesylate decreases the production of inflammatory mediators in rheumatoid arthritis synovial fibroblasts by activating CB2, TRPV1, TRPA1 and yet unidentified receptor targets

Background

In rheumatoid arthritis (RA), synovial fibroblasts (SF) secrete large amounts of IL-6, IL-8 and matrix metalloproteinases (MMPs) which are crucial for cartilage destruction. RASFs are sensitive to the action of cannabinoids and they not only express cannabinoid receptors type I and II (CB₁ and CB₂) but also transient receptor potential channels type vanilloid (TRPV1) and ankyrin (TRPA1). The synthetic cannabinoid WIN55,212-2 mesylate (WIN) demonstrated strong anti-inflammatory effects in monocytes and synovial fibroblasts only in high concentrations in a non-cannabinoid receptor dependent manner. In this study we assessed the ability of WIN to modulate cytokine and MMP-3 production in SFs over a wide concentration range and identified specific receptor targets that mediate the effects of this synthetic cannabinoid.

Methods

MMP-3, IL-6 and IL-8 were determined by ELISA. Adhesion was measured by the XCELLigence system. Proliferation was assessed by cell titer blue assays.

Results

WIN significantly reduced TNF-induced IL-6, IL-8 and MMP-3 production in concentrations below 2 μM, while higher concentrations completely inhibited production of IL-6 and IL-8 but increased extracellular MMP-3 levels. The inhibitory effect at low concentrations (<2 μM) was independent on activation of either CB₁ or CB₂ but was attenuated by TRPV1 or TRPA1 inhibition in OASFs and RASFs. The effects of high concentrations of WIN on cytokine and MMP-3 production were decreased by the calcium chelating agent BAPTA, the AMPK activator metformin, the TRPA1 antagonist A967079 and the CB₂ antagonist COR170. Furthermore, fetal calf serum content in culture media strongly influenced the efficacy of WIN at high concentrations. In addition, high concentrations of WIN also diminished SF adhesion and proliferation without altering cell viability whereas low concentrations promoted SF adhesion without any influence on proliferation.

Conclusion

The synthetic cannabinoid WIN in low concentrations exhibits anti-inflammatory effects in synovial fibroblasts independent of CB₁ and CB₂ while CB₂ and yet unidentified receptor targets are responsible for WIN effects in micromolar concentrations. Our results indicate a TRPV1/TRPA1 dependent mechanism of SF regulation that might be coupled to cellular energy status and calcium content.

Gypenoside L, Isolated from Gynostemma pentaphyllum, Induces Cytoplasmic Vacuolation Death in Hepatocellular Carcinoma Cells through Reactive-Oxygen-Species-Mediated Unfolded Protein Response

Exploring novel anticancer agents that can trigger non-apoptotic or non-autophagic cell death is urgent for cancer treatment. In this study, we screened and identified an unexplored anticancer activity of gypenoside L (Gyp-L) isolated from Gynostemma pentaphyllum. We showed that treatment with Gyp-L induces non-apoptotic and non-autophagic cytoplasmic vacuolation death in human hepatocellular carcinoma (HCC) cells. Mechanically, Gyp-L initially increased the intracellular reactive oxygen species (ROS) levels, which, in turn, triggered protein ubiquitination and unfolded protein response (UPR), resulting in Ca(2+) release from endoplasm reticulum (ER) inositol trisphosphate receptor (IP3R)-operated stores and finally cytoplasmic vacuolation and cell death. Interruption of the ROS-ER-Ca(2+) signaling pathway by chemical inhibitors significantly prevented Gyp-L-induced vacuole formation and cell death. In addition, Gyp-L-induced ER stress and vacuolation death required new protein synthesis. Overall, our works provide strong evidence for the anti-HCC activity of Gyp-L and suggest a novel therapeutic option by Gyp-L through the induction of a unconventional ROS-ER-Ca(2+)-mediated cytoplasmic vacuolation death in human HCC.

The use of cannabinoids as anticancer agents

It is well-established that cannabinoids exert palliative effects on some cancer-associated symptoms. In addition evidences obtained during the last fifteen years support that these compounds can reduce tumor growth in animal models of cancer. Cannabinoids have been shown to activate an ER-stress related pathway that leads to the stimulation of autophagy-mediated cancer cell death. In addition, cannabinoids inhibit tumor angiogenesis and decrease cancer cell migration. The mechanisms of resistance to cannabinoid anticancer action as well as the possible strategies to develop cannabinoid-based combinational therapies to fight cancer have also started to be explored. In this review we will summarize these observations (that have already helped to set the bases for the development of the first clinical studies to investigate the potential clinical benefit of using cannabinoids in anticancer therapies) and will discuss the possible future avenues of research in this area.

Cannabinoids as therapeutic agents in cancer: current status and future implications

The pharmacological importance of cannabinoids has been in study for several years. Cannabinoids comprise of (a) the active compounds of the Cannabis sativa plant, (b) endogenous as well as (c) synthetic cannabinoids. Though cannabinoids are clinically used for anti-palliative effects, recent studies open a promising possibility as anti-cancer agents. They have been shown to possess anti-proliferative and anti-angiogenic effects in vitro as well as in vivo in different cancer models. Cannabinoids regulate key cell signaling pathways that are involved in cell survival, invasion, angiogenesis, metastasis, etc. There is more focus on CB1 and CB2, the two cannabinoid receptors which are activated by most of the cannabinoids. In this review article, we will focus on a broad range of cannabinoids, their receptor dependent and receptor independent functional roles against various cancer types with respect to growth, metastasis, energy metabolism, immune environment, stemness and future perspectives in exploring new possible therapeutic opportunities.

Downstream effects of endocannabinoid on blood cells: implications for health and disease

Endocannabinoids (eCBs), among which N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) are the most biologically active members, are polyunsaturated lipids able to bind cannabinoid, vanilloid and peroxisome proliferator-activated receptors. Depending on the target engaged, these bioactive mediators can regulate different signalling pathways, at both central and peripheral levels. The biological action of eCBs is tightly controlled by a plethora of metabolic enzymes which, together with the molecular targets of these substances, form the so-called "endocannabinoid system". The ability of eCBs to control manifold peripheral functions has received a great deal of attention, especially in the light of their widespread distribution in the body. In particular, eCBs are important regulators in blood, where they modulate haematopoiesis, platelet aggregation and apoptosis, as well as chemokine release and migration of immunocompetent cells. Here, we shall review the current knowledge on the pathophysiological roles of eCBs in blood. We shall also discuss the involvement of eCBs in those disorders affecting the haematological system, including cancer and inflammation. Knowledge gained to date underlines a fundamental role of the eCB system in blood, thus suggesting that it may represent a therapeutic promise for a broad range of diseases involving impaired hematopoietic cell functions.

Influence of rimonabant treatment on peripheral blood mononuclear cells; flow cytometry analysis and gene expression profiling

The cannabinoid receptor type 1 (CB1) antagonist rimonabant has been used as treatment for obesity. In addition, anti-proliferative effects on mitogen-activated leukocytes have been demonstrated in vitro. We have previously shown that rimonabant (SR141716A) induces cell death in ex vivo isolated malignant lymphomas with high expression of CB1 receptors. Since CB1 targeting may be part of a future lymphoma therapy, it was of interest to investigate possible effects on peripheral blood mononuclear cells (PBMC) in patients treated with rimonabant. We therefore evaluated leukocyte subsets by 6 color flow cytometry in eight patients before and at treatment with rimonabant for 4 weeks. Whole-transcript gene expression profiling in PBMC before and at 4 weeks of rimonabant treatment was done using Affymetrix Human Gene 1.0 ST Arrays. Our data show no significant changes of monocytes, B cells, total T cells or T cell subsets in PBMC during treatment with rimonabant. There was a small but significant increase in CD3-, CD16+ and/or CD56+ cells after rimonabant therapy. Gene expression analysis detected significant changes in expression of genes associated with innate immunity, cell death and metabolism. The present study shows that normal monocytes and leukocyte subsets in blood remain rather constant during rimonabant treatment. This is in contrast to the induction of cell death previously observed in CB1 expressing lymphoma cells in response to treatment with rimonabant in vitro. These differential effects observed on normal and malignant lymphoid cells warrant investigation of CB1 targeting as a potential lymphoma treatment.

Nonautophagic cytoplasmic vacuolation death induction in human PC-3M prostate cancer by curcumin through reactive oxygen species -mediated endoplasmic reticulum stress

The antiapoptotic and antiautophagic abilities of cancer cells constitute a major challenge for anticancer drug treatment. Strategies for triggering nonapoptotic or nonautophagic cell death may improve therapeutic efficacy against cancer. Curcumin has been reported to exhibit cancer chemopreventive properties. Herein, we report that curcumin induced apoptosis in LNCaP, DU145, and PC-3 cells but triggered extensive cytoplasmic vacuolation in PC-3M cells. Electron microscopic images showed that the vacuoles lacked intracellular organelles and were derived from the endoplasmic reticulum (ER). Moreover, curcumin-induced vacuolation was not reversed by an apoptosis- or autophagy-related inhibitor, suggesting that vacuolation-mediated cell death differs from classical apoptotic and autophagic cell death. Mechanistic investigations revealed that curcumin treatment upregulated the ER stress markers CHOP and Bip/GRP78 and the autophagic marker LC3-II. In addition, curcumin induced ER stress by triggering ROS generation, which was supported by the finding that treating cells with the antioxidant NAC alleviated curcumin-mediated ER stress and vacuolation-mediated death. An in vivo PC-3M orthotopic prostate cancer model revealed that curcumin reduced tumor growth by inducing ROS production followed by vacuolation-mediated cell death. Overall, our results indicated that curcumin acts as an inducer of ROS production, which leads to nonapoptotic and nonautophagic cell death via increased ER stress.

The evolving role of the endocannabinoid system in gynaecological cancer

BACKGROUND

The 'endocannabinoid system' (ECS), comprising endogenous ligands (endocannabinoids) and their regulating enzymes, together with the cannabinoid receptors, has attracted a great deal of attention because it affects not only all facets of human reproduction, from gametogenesis through to parturition and beyond, but also targets key mechanisms affecting some hallmarks of cancer. Recent evidence showing that cannabinoid receptors play a very important role in the development of malignancies outside of the reproductive organs suggests a similar role for the ECS in the establishment or continued development of gynaecological malignancy.

METHODS

Primary papers and review articles, and primary sources within these papers, up to December 2014, on the evolving role of the ECS in cancer, with a special focus on gynaecological cancers, were obtained by Medline and PubMed searches using the search terms: 'cancer', 'cannabinoid', 'endocannabinoid', 'gynaecology' and 'malignancy'. Non-English manuscripts were excluded.

RESULTS

More than 2100 sources were obtained from which only 112 were specifically important to the topic. Analysis of those articles supports a role of the ECS in gynaecological cancers but leaves many gaps in our knowledge that need to be filled. How some of the relevant receptors are activated and cause changes in cell phenotypes that progress to malignancy remains undiscovered and an area for future research. Increasing evidence suggests that malignant transformation within the female genital tract could be accompanied by deregulation of components of the ECS, acting through rather complex cannabinoid receptor-dependent and receptor-independent mechanisms.

CONCLUSIONS

The paucity of studies in this area suggests that research using animal models is needed to evaluate endocannabinoid signalling in cancer networks. Future randomized clinical studies should reveal whether endocannabinoids or their derivatives prove to be useful therapeutic targets for gynaecological and other cancers.

A phosphorescent rhenium(i) histone deacetylase inhibitor: mitochondrial targeting and paraptosis induction

A phosphorescent rhenium(i) tricarbonyl polypyridine complex with mitochondria-specific localization, HDAC inhibitory activity and paraptosis-inducing capability has been explored as a multifunctional agent.

Perturbations of the endocannabinoid system in mantle cell lymphoma: correlations to clinical and pathological features

The cannabinoid receptors are upregulated in many types of cancers, including mantle cell lymphoma (MCL) and have been suggested to constitute novel therapeutic targets. The expression pattern of the key members of the endocannabinoid system was analyzed in a well-characterized MCL patient cohort and correlated to biological features. 107 tumor tissues were analyzed for the mRNA levels of cannabinoid receptors 1 and 2 (CNR1 and CNR2) and the two main enzymes regulating the endocannabinoid anandamide levels in tissue: NAPEPLD and FAAH (participating in synthesis and degradation, respectively). NAPEPLD, CNR1 and CNR2 were overexpressed while FAAH expression was reduced in MCL compared to non-malignant B-cells. Both low CNR1 and high FAAH levels correlated with lymphocytosis (p=0.016 and p=0.022, respectively) and with leukocytosis (p=0.0018 and p=0.047). Weak to moderate CNR1 levels were a feature of SOX11 negative MCL (p=0.006). Both high CNR2 and high FAAH levels correlated to anemia (p=0.0006 and p=0.038, respectively). In conclusion, the relative expression of the anandamide synthesizing and metabolizing enzymes in MCL is heavily perturbed. This finding, together with high expression of cannabinoid receptors, could favor enhanced anandamide signaling and suggest that targeting the endocannabinoid system might be considered as part of lymphoma therapy.

Methuosis: nonapoptotic cell death associated with vacuolization of macropinosome and endosome compartments

Apoptosis is the most widely recognized form of physiological programmed cell death. During the past three decades, various nonapoptotic forms of cell death have gained increasing attention, largely because of their potential importance in pathological processes, toxicology, and cancer therapy. A recent addition to the panoply of cell death phenotypes is methuosis. The neologism is derived from the Greek methuo (to drink to intoxication) because the hallmark of this form of cell death is displacement of the cytoplasm by large fluid-filled vacuoles derived from macropinosomes. The demise of the cell resembles many forms of necrosis, insofar as there is a loss of metabolic capacity and plasma membrane integrity, without the cell shrinkage and nuclear fragmentation associated with apoptosis. Methuosis was initially defined in glioblastoma cells after ectopic expression of activated Ras, but recent reports have described small molecules that can induce the features of methuosis in a broad spectrum of cancer cells, including those that are resistant to conventional apoptosis-inducing drugs. This review summarizes the available information about the distinguishing morphological characteristics and underlying mechanisms of methuosis. We compare and contrast methuosis with other cytopathological conditions in which accumulation of clear cytoplasmic vacuoles is a prominent feature. Finally, we highlight key questions that need to be answered to determine whether methuosis truly represents a unique form of regulated cell death.