Piperlongumine selectively suppresses ABC-DLBCL through inhibition of NF-κB p65 subunit nuclear import

The Antitumor Activity of Piplartine: A Review

Cancer is a worldwide health problem with high mortality in children and adults, making searching for novel bioactive compounds with potential use in cancer treatment essential. Piplartine, also known as piperlongumine, is an alkamide isolated from Piper longum Linn, with relevant therapeutic potential. Therefore, this review covered research on the antitumor activity of piplartine, and the studies reported herein confirm the antitumor properties of piplartine and highlight its possible application as an anticancer agent against various types of tumors. The evidence found serves as a reference for advancing mechanistic research on this metabolite and preparing synthetic derivatives or analogs with better antitumor activity in order to develop new drug candidates.

Cyclin-dependent kinase 7/9 inhibitor SNS-032 induces apoptosis in diffuse large B-cell lymphoma cells

Approximately 40% of patients with diffuse large B-cell lymphoma (DLBCL) are refractory or relapse to standard chemotherapy, and most of them are activated B cell-like DLBCLs (ABC-DLBCL) and germinal center B cell-like DLBCLs (GCB-DLBCL). SNS-032, a novel and selective CDK7/9 inhibitor, that the first phase clinical trials approved by US FDA for cancer treatment have been completed. In this study, we investigated the anti-tumor effect of SNS-032 in ABC- and GCB-DLBCL subtypes. We report that SNS-032 induced growth inhibition and cell apoptosis in both DLBCL cells in vitro, and inhibited the growth of both DLBCL xenografts in nude mice. Mechanistically, SNS-032 inhibited RNA polymerase II, which led to transcriptional-dependent suppression of NF-κB signaling pathway and its downstream targets involved in cell survival; SNS-032 also downregulates BCL-2 and c-MYC in both mRNA and protein levels. Significantly, these findings provide pre-clinical evidence for application of targeting the CDK7/9 in DLBCL.

The Expression of Matrix Metalloproteinases in Eyes with Intraocular Lymphoma

PURPOSE

The purpose of this study is to investigate matrix metalloproteinases (MMPs) expression in human intraocular lymphoma (IOL).

METHODS

Two enucleated eyes and seven cell-block samples obtained from patients with IOL who underwent vitrectomy were used. Immunopathological examinations were performed for detection of MMP-2, MMP-9, and TIMP-4 expressions.

RESULTS

In the enucleated eye with primary IOL (PIOL), MMP-2 was negative, and MMP-9 and TIMP-4 were positive in the lymphoma cells, while in the enucleated eye with secondary IOL (SIOL), all the molecules were positive. Among the cell-block samples with PIOL, the positive rate in lymphoma cells of MMP-2, MMP-9, and TIMP-4 was 75%, 100%, and 75%, respectively. In the cell-block samples with SIOL, the positive rates of MMP-2, MMP-9, and TIMP-4 were all 100%.

CONCLUSIONS

MMP-2, MMP-9, and TIMP-4 were expressed in lymphoma cells using the specimens of human IOL, suggesting that MMPs may play an important role in the development of IOL.

The promising potential of piperlongumine as an emerging therapeutics for cancer

In spite of the immense advancement in the diagnostic and treatment modalities, cancer continues to be one of the leading causes of mortality across the globe, responsible for the death of around 10 million patients every year. The foremost challenges faced in the treatment of this disease are chemoresistance, adverse effects of the drugs, and the high cost of treatment. Though scientific studies over the past few decades have foreseen and are focusing on the cancer-preventive and therapeutic potential of natural products and their underlying mechanism of action, many more of these agents are not still explored. Piperlongumine (PL), or piplartine, is one such alkaloid isolated from Piper longum Linn. which is shown to be safe and has significant potential in the prevention and therapy of cancer. Numerous shreds of evidence have established the ability of this alkaloid and its analogs and nanoformulations in modulating various complex molecular pathways such as phosphatidylinositol-3-kinase/protein kinase B /mammalian target of rapamycin, nuclear factor kappa-B, Janus kinases/signal transducer and activator of transcription 3, etc. and inhibit different hallmarks of cancer such as cell survival, proliferation, invasion, angiogenesis, epithelial-mesenchymal-transition, metastases, etc. In addition, PL was also shown to inhibit radioresistance and chemoresistance and sensitize the cancer cells to the standard chemotherapeutic agents. Therefore, this compound has high potential as a drug candidate for the prevention and treatment of different cancers. The current review briefly reiterates the anti-cancer properties of PL against different types of cancer, which permits further investigation by conducting clinical studies.

Piperlongumine promotes death of retinoblastoma cancer cells

Retinoblastoma is the most common pediatric intraocular malignant tumor. While retinoblastoma initiation is triggered by the inactivation of both alleles of the retinoblastoma tumor suppressor gene (RB1) in the developing retina, tumor progression requires additional epigenetic changes, retinoblastoma genomes being quite stable. Although the management of RB has recently improved, new therapeutic agents are necessary to improve the treatment of advanced forms of retinoblastoma.

In this report, we analyzed the pro-death effect of piperlongumine (PL), a natural compound isolated from Piper longum L., on two human retinoblastoma cell lines, WERI-Rb and Y79. The effects of PL on cell proliferation, cell death and cell cycle were investigated. PL effectively inhibited cell growth, impacted the cell cycle by decreasing the level of cyclins and CDK1 and increasing CDKN1A and triggered a caspase-3 independant cell death process in which reactive oxygen species (ROS) production is a major player. Indeed, PL toxicity in retinoblastoma cell lines was inhibited by a ROS scavenger N-acetyl-l-cysteine (NAC) treatment. These findings suggest that PL reduces tumor growth and induces cell death by regulating the cell cycle.

Piperlongumine targets NF-κB and its downstream signaling pathways to suppress tumor growth and metastatic potential in experimental colon cancer

NF-κB is the principle transcription factor and plays the central role in orchestrating chronic inflammation by regulating levels of cytokines, chemokines and growth factors. Piperlongumine (PL), a major alkaloid in the fruit of Piper longum Linn. has gained worldwide attention for its anticancer properties, however, its mechanism of action in the chemoprevention of colon cancer has not been investigated yet. Therefore, the present study was designed to elucidate the underlying molecular mechanism of PL in preventing DMH/DSS induced experimental colon cancer in mice. In the current study well established DMH/DSS induced experimental colon cancer mouse model was used to demonstrate the chemopreventive potential of PL. The expression of NF-κB and its downstream target proteins was evaluated mainly through western blotting. In addition, CAM assay, immunohistochemical staining and gelatin zymography was used to show anti-angiogenic and anti-invasive potential of PL. Additionally, important tumor biomarkers such as TSA, LASA, LDH and IL-6 levels were also estimated. The results of current study showed that PL was capable to inhibit NF-κB activation as well as its nuclear translocation. PL administration to DMH/DSS treated mice also inhibited the NF-κB downstream signaling cascades such as including COX-2 pathway, JAK/STAT pathway, β-catenin, Notch signaling pathway, angiogenesis and epithelial to mesenchymal transition pathway. The findings of the present study have claimed PL as promising chemopreventive agent for colon cancer with pleiotropic action. The current study emphasizes that regular consumption of PL can be an effective approach in the prevention of colon cancer in humans.

The Natural Alkaloid Piperlongumine Inhibits Metastatic Activity and Epithelial-to-Mesenchymal Transition of Triple-Negative Mammary Carcinoma Cells

In this study, we determined the effect of low dose piperlongumine on the motility/invasive capacity and epithelial-to-mesenchymal transition (EMT) of MDA-MB-231 triple-negative breast cancer (TNBC) cells and the metastasis of 4T1 mouse mammary carcinoma cells. MTT assays measured the effect of piperlongumine on TNBC cell growth. Motility/invasiveness were determined by gap closure/transwell assays. Western blotting assessed ZEB1, Slug, and matrix metalloproteinase (MMP) 9 expression. Interleukin (IL) 6 was detected by ELISA. MMP2, E-cadherin, and miR-200c expression was determined by real-time quantitative polymerase chain reaction. Reactive oxygen species (ROS) were measured by flow cytometry. The orthotopic 4T1 mouse model of breast cancer was used to examine metastasis. Piperlongumine-treated MDA-MB-231 cells showed reduced motility/invasiveness, decreased MMP2 and MMP9 expression, increased miR-200c expression, reduced IL-6 synthesis, decreased expression of ZEB1 and Slug, increased E-cadherin expression, and epithelial-like morphology. Piperlongumine also inhibited transforming growth factor β-induced ZEB1 and Slug expression. ROS accumulated in piperlongumine-treated cells, while changes in metastasis-associated gene expression were ablated by exogenous glutathione. Metastasis of 4T1 cells to the lungs of BALB/c mice was dramatically reduced in piperlongumine-treated animals. These findings reveal a previously unknown capacity of low dose piperlongumine to interfere with TNBC metastasis via an oxidative stress-dependent mechanism.

Signal Pathways and Therapeutic Prospects of Diffuse Large B Cell Lymphoma

BACKGROUND

Diffuse Large B Cell Lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma which is heterogeneous both clinically and morphologically. Over the past decades, significant advances have been made in the understanding of the molecular genesis, leading to the identification of multiple pathways and molecules that can be targeted for clinical benefit.

OBJECTIVE

The current review aims to present a brief overview of signal pathways of DLBCL, which mainly focus on B-cell antigen Receptor (BCR), Nuclear Factor-κB (NF-κB), Phosphatidylinositol-3-Kinase (PI3K) - protein kinase B (Akt) - mammalian Target of Rapamycin (mTOR), Janus Kinase (JAK) - Signal Transducer and Activator (STAT), Wnt/β-catenin, and P53 pathways.

METHODS

Activation of signal pathways may contribute to the generation, development, chemotherapy sensitivity of DLBCL, and expression of pathway molecules is associated with the prognosis of DLBCL. Some agents targeting these pathways have been proved effective and relevant clinical trials are in progress. These agents used single or combined with chemotherapy/each other might raise the possibility of improving clinical outcomes in DLBCL.

CONCLUSION

This review presents several signal pathways of DLBCL and targeted agents had a tendency to improve the curative effect, especially in high-risk or relapsed/refractory DLBCL.

Two Natural Alkaloids Synergistically Induce Apoptosis in Breast Cancer Cells by Inhibiting STAT3 Activation

Breast cancer has become a worldwide threat, and chemotherapy remains a routine treatment. Patients are forced to receive continuous chemotherapy and suffer from severe side effects and poor prognosis. Natural alkaloids, such as piperine (PP) and piperlongumine (PL), are expected to become a new strategy against breast cancer due to their reliable anticancer potential. In the present study, cell viability, flow cytometry, and Western blot assays were performed to evaluate the suppression effect of PP and PL, alone or in combination. Data showed that PP and PL synergistically inhibited breast cancer cells proliferation at lower doses, while only weak killing effect was observed in normal breast cells, indicating a good selectivity. Furthermore, apoptosis and STAT3 signaling pathway-associated protein levels were analyzed. We demonstrated that PP and PL in combination inhibit STAT3 phosphorylation and regulate downstream molecules to induce apoptosis in breast cancer cells. Taken together, these results revealed that inactivation of STAT3 was a novel mechanism with treatment of PP and PL, suggesting that combination application of natural alkaloids may be a potential strategy for prevention and therapy of breast cancer.

Phytochemicals in Anticancer Drug Development

BACKGROUND

In spite of major technological advances in conventional therapies, cancer continues to remain the leading cause of mortality worldwide. Phytochemicals are gradually emerging as a rich source of effective but safer agents against many life-threatening diseases.

METHODS

Various phytochemicals with reported anticancer activity have been simply categorized into major phytoconstituents- alkaloids, polyphenols, saponins, tannins and terpenoids.

RESULTS

The adverse effects associated with currently available anticancer medications may be overcome by using plant-derived compounds either alone or in combination. Exploration of plant kingdom may provide new leads for the accelerated development of new anticancer agents.

CONCLUSION

Although numerous potent synthetic drugs have been introduced for cancer chemotherapy, yet their serious toxicity concerns to normal cells apart from drug resistance have emerged as the major obstacles for their clinical utility over a prolonged duration of time. Current status and potential of phytochemicals and their derivatives in cancer therapy have been briefly reviewed in the present manuscript.

High expression of Bruton's tyrosine kinase (BTK) is required for EGFR-induced NF-κB activation and predicts poor prognosis in human glioma

BACKGROUND

Malignant glioma is the most common primary brain tumor in adults and has a poor prognosis. However, there are no effective targeted therapies for glioma patients. Thus, the development of novel targeted therapeutics for glioma is urgently needed.

METHODS

In this study, we examined the prognostic significance BTK expression in patients with glioma. Furthermore, we investigated the mechanism and therapeutic potential of ibrutinib in the treatment of human glioma in vitro and in vivo.

RESULTS

Our data demonstrate that high expression of BTK is a novel prognostic marker for poor survival in patients with glioma. BTK-specific inhibitor ibrutinib effectively inhibits the proliferation, migration and invasion ability of glioma cells. Furthermore, ibrutinib can induce G1 cell-cycle arrest by regulating multiple cell cycle-associated proteins. More importantly, we found that BTK inhibition significantly blocks the degradation of IκBα and prevents the nuclear accumulation of NF-κB p65 subunit induced by EGF in glioma cells.

CONCLUSIONS

Taken together, our study suggests that BTK is a novel prognostic marker and molecular therapeutic target for glioma. BTK is required for EGFR-induced NF-κB activation in glioma cells. These findings provide the basis for future clinical studies of ibrutinib for the treatment of glioma.

Smoothened is a poor prognosis factor and a potential therapeutic target in glioma

Malignant gliomas are associated with a high mortality rate. Thus, there is an urgent need for the development of novel targeted therapeutics. Aberrant Hedgehog signaling has been directly linked to glioma. GDC-0449 is a novel small molecule inhibitor of Hedgehog signaling that blocks the activity of smoothened (Smo). In this study, we evaluated the in vitro and in vivo effects of the smoothened inhibitor GDC-0449 on cell proliferation in human gliomas. We found that high expression of smoothened in glioma is a predictor of short overall survival and poor patient outcome. Our data suggest that GDC-0449 significantly inhibits the proliferation of glioma cells by inducing cell cycle arrest at the G1 phase. Our results demonstrate that GDC-0449 can effectively inhibit the migration and invasion of glioma cells. Furthermore, GDC-0449 treatment significantly suppressed glioma cell xenograft tumorigenesis. Mechanistically, GDC-0449 treatment markedly decreases the expression levels of key Hedgehog pathway component genes (Shh, Patched-1, Patched-2, smoothened, Gli1 and Gli2). These results indicate that GDC-0449 works through targeting the Hedgehog pathway. Taken together, our study suggests that smoothened could be used as a prognostic marker and molecular therapeutic target for glioma.

Emerging Cytotoxic Alkaloids in the Battle against Cancer: Overview of Molecular Mechanisms

Considered as the second deadliest disease globally, cancer has captured the attention of researchers who have been trying with perseverance to decode its hidden aspects, to find new prognosis methods, and to develop better and more effective treatments. Plants have continuously offered an excess of unique secondary metabolites with remarkable biological applications. Alkaloids, one of the most abundant metabolites, constitute a large conglomerate of basic heterocyclic nitrogen-containing natural compounds which are normally produced by plants as toxic substances. Out of the 27,000 different alkaloids, more than 17,000 have displayed diversified pharmacological properties including anticancer activities. These metabolites have been classified either according to their chemical structures or their taxonomic origin. None of the researched alkaloids have been classified according to their molecular mechanism of action against cancer. In fact, only a fraction of the tremendous number of anticancer alkaloids has been copiously mentioned in journals. Here, we aim to provide a summary of the literature on some of the promising anticancer alkaloids that have not been well discussed previously and to classify them according to their molecular mechanisms of action. This review will provide a better understanding of the anticancer mechanisms of these promising natural products that are a rich reservoir for drug discovery.

Piperlongumine attenuates experimental autoimmune encephalomyelitis through inhibition of NF-kappaB activity

Multiple sclerosis (MS) is a chronic, autoimmune and neurodegenerative disease in which demyelination sporadically and repeatedly occurs in the central nervous system (CNS). The activity of nuclear factor kappa B (NF-κB), a family of transcription factors, was increased in the cerebrospinal fluid (CSF) and/or the serum and brain and/or spinal cord of MS patients than in a healthy donors. In our study, we investigated whether piperlongumine (PL), which is known to have inhibitory effect on activity of NF-κB, can alleviate an experimental autoimmune encephalomyelitis (EAE). The mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55), and then we injected PL (1.5mg/kg/day or 3.0mg/kg/day) into the mice intraperitoneally on every second day from days 2 to 28. For in vitro study, we treated PL (0.5, 1 and 2.5μM) to RAW 264.7 and Jurkat cells with each stimulator. We observed that the paralytic severity and neuropathology of EAE in PL-treated group were decreased compared with the EAE group. PL showed a suppressed effect on demyelination, immune cells infiltration, astrocytes/microglials activation, level of inflammatory cytokines and proteins as well as NF-κB activity. Production of inflammatory cytokines and proteins as well as translocation of NF-κB into nucleus by treatment stimulators in RAW 264.7 and Jurkat cells were reduced by PL. Moreover, treatment of NF-κB inhibitor further inhibited production of inflammatory cytokines and proteins. These results suggest that PL can mitigate MOG-induced EAE symptoms and activation of macrophages and T cells by inhibiting NF-κB signaling. Therefore, PL could be useful for the treatment for MS.

Structural and Biochemical Analyses Reveal the Mechanism of Glutathione S-Transferase Pi 1 Inhibition by the Anti-cancer Compound Piperlongumine

Glutathione S-transferase pi 1 (GSTP1) is frequently overexpressed in cancerous tumors and is a putative target of the plant compound piperlongumine (PL), which contains two reactive olefins and inhibits proliferation in cancer cells but not normal cells. PL exposure of cancer cells results in increased reactive oxygen species and decreased GSH. These data in tandem with other information led to the conclusion that PL inhibits GSTP1, which forms covalent bonds between GSH and various electrophilic compounds, through covalent adduct formation at the C7-C8 olefin of PL, whereas the C2-C3 olefin of PL was postulated to react with GSH. However, direct evidence for this mechanism has been lacking. To investigate, we solved the X-ray crystal structure of GSTP1 bound to PL and GSH at 1.1 Å resolution to rationalize previously reported structure activity relationship studies. Surprisingly, the structure showed that a hydrolysis product of PL (hPL) was conjugated to glutathione at the C7-C8 olefin, and this complex was bound to the active site of GSTP1; no covalent bond formation between hPL and GSTP1 was observed. Mass spectrometry (MS) analysis of the reactions between PL and GSTP1 confirmed that PL does not label GSTP1. Moreover, MS data also indicated that nucleophilic attack on PL at the C2-C3 olefin led to PL hydrolysis. Although hPL inhibits GSTP1 enzymatic activity in vitro, treatment of cells susceptible to PL with hPL did not have significant anti-proliferative effects, suggesting that hPL is not membrane-permeable. Altogether, our data suggest a model wherein PL is a prodrug whose intracellular hydrolysis initiates the formation of the hPL-GSH conjugate, which blocks the active site of and inhibits GSTP1 and thereby cancer cell proliferation.

Discovery of piperlongumine as a potential novel lead for the development of senolytic agents

Accumulating evidence indicates that senescent cells play an important role in many age-associated diseases. The pharmacological depletion of senescent cells (SCs) with a "senolytic agent", a small molecule that selectively kills SCs, is a potential novel therapeutic approach for these diseases. Recently, we discovered ABT-263, a potent and highly selective senolytic agent, by screening a library of rationally-selected compounds. With this screening approach, we also identified a second senolytic agent called piperlongumine (PL). PL is a natural product that is reported to have many pharmacological effects, including anti-tumor activity. We show here that PL preferentially killed senescent human WI-38 fibroblasts when senescence was induced by ionizing radiation, replicative exhaustion, or ectopic expression of the oncogene Ras. PL killed SCs by inducing apoptosis, and this process did not require the induction of reactive oxygen species. In addition, we found that PL synergistically killed SCs in combination with ABT-263, and initial structural modifications to PL identified analogs with improved potency and/or selectivity in inducing SC death. Overall, our studies demonstrate that PL is a novel lead for developing senolytic agents.

PMA/IONO affects diffuse large B-cell lymphoma cell growth through upregulation of A20 expression

Diffuse large B-cell lymphoma (DLBCL) is a common non-Hodgkin lymphoma. A20 and mucosa-associated lymphoid tissue lymphoma translocation gene 1 (MALT1) are known to be related to DLBCL pathogenesis and progression. This study aimed to assess the effects of phorbol myristate acetate/ionomycin (PMA/IONO) on the growth and apoptosis of the DLBCL cell line OCI-LY1, and their associations with A20, MALT1 and survivin levels. Cell viability was assessed by MTT assay. Cell cycle distribution and apoptosis were evaluated using flow cytometry after incubation with Annexin V-FITC/propidium iodide (PI) and RNase/PI, respectively. Gene and protein expression levels were determined by quantitative real-time PCR and western blotting, respectively. To further determine the role of A20, this gene was silenced in the OCI-LY1 cell line by specific siRNA transfection. A20 protein levels were higher in the OCI-LY1 cells treated with PMA/IONO compared with the controls, and were positively correlated with the concentration and treatment time of IONO, but not with changes of PMA and MALT1. Meanwhile, survivin expression was reduced in the OCI-LY1 cells after PMA/IONO treatment. In addition, OCI-LY1 proliferation was markedly inhibited, with a negative correlation between cell viability and IONO concentration. In concordance, apoptosis rates were higher in the OCI-LY1 cells after PMA + IONO treatment. Cell cycle distribution differed between the OCI-LY1 cells with and without PMA/IONO treatment only at 24 h, with increased cells in the G0/G1 stage after PMA/IONO treatment. These findings indicate that PMA/IONO promotes the apoptosis and inhibits the growth of DLBCL cells, in association with A20 upregulation. Thus, A20 may be a potential therapeutic target for DLBCL.