Molecular mechanism of C-phycocyanin induced apoptosis in LNCaP cells.

The usefulness of Marine-derived products as the source of anticancer agents has been explored for many decades. The objective of our study was to investigate the molecular mechanism by which C-PC induces apoptosis in monotherapy as well as in combination treatment with a known chemotherapeutic drug named Topotecan (TPT) using prostate cancer cells (LNCaP). To determine the intracellular mechanism of action, we analyzed the gene expression profile of C-PC treated cells using human apoptosis RT2 profiler PCR array, which indicated that C-PC was able to regulate both anti- and pro-apoptotic genes significantly. Detailed analysis revealed increases in the levels of Bax, Apaf-1 (pro-apoptotic proteins) along with the activation of the key apoptotic proteases such as caspase-8, caspase-9, and caspase-3. Similarly, analysis of anti-apoptotic proteins demonstrated a decrease in the expression of Bcl-2, Mcl-1, and survivin. Results from the whole-cell incubation studies indicated that C-PC was only binding to the plasma membrane-associated receptor proteins. LNCaP cells treated with C-PC alone and in combination with TPT showed increased expression of the death receptor FAS (also known as FAS or CD95) along with cleaved PARP, confirming its importance. Our study is significant since it is providing greater insight into the apoptotic mechanisms triggered by C-PC as well as emphasizing the involvement of FAS in mediating its effects. Furthermore, our results with combination treatments suggest that-PC could improve the anticancer effects of drugs such as TPT that are currently used for cancer treatments. In addition, use of C-PC in combination can also diminish the side effects resulting from conventional chemotherapeutic agents such as TPT.

Anti-cancer effects of F16: A novel vascular endothelial growth factor receptor-specific inhibitor.

Vascular endothelial growth factor receptor-2 is a dynamic target for therapeutic intervention in various types of cancers. This study was aimed to explore the anti-angiogenic activity of a novel vascular endothelial growth factor receptor-specific inhibitor named F16 in both in vitro and in vivo experimental models. This compound effectively reduced cell proliferation, tube formation, and migration of human umbilical vein endothelial cells in a concentration-dependent manner by directly inhibiting vascular endothelial growth factor binding and subsequent vascular endothelial growth factor receptor-2 phosphorylation. The F16 was also able to inhibit the phosphoinositide 3-kinase/protein kinase B-mediated survival and migration pathways in cancer in addition to inhibiting the focal adhesion kinase and mitogen-activated protein kinases-mediated signaling in GI-101A cancer cells. The chorioallantoic membrane assay followed by tumor growth inhibition measurements with GI-101A breast cancer xenograft implanted athymic nude mice confirmed the in vivo tumor reductive effects of F16. It was interesting to observe a decrease in tumor burden after F16 treatment which correlated very well with the decrease in the plasma levels of mucin-1 (MUC-1). Our studies so far have confirmed that F16 is a specific inhibitor of angiogenesis in both in vitro and in vivo models. The F16 also works very efficiently with Taxol in combination by limiting the tumor growth that is better than the monotherapy with any one of the drugs that were tested individually. Thus, F16 offers a promising anti-proliferative and anti-angiogenic effects with better specificity than some of the existing multi-kinase inhibitors.

Pro-angiogenic effects of MDM2 through HIF-1α and NF-κB mediated mechanisms in LNCaP prostate cancer cells.

Hypoxia stimulates several pathways that are critical to cancer cell growth and survival, including activation of vascular endothelial growth factor (VEGF) transcription. Overexpression of VEGF and the extent of neoangiogenesis are closely correlated with tumor development and cancer metastases. Recent studies suggest MDM2 as one of the major regulators of pro-angiogenic mechanisms. To assess the direct correlation of HIF-1α and NF-κB, and the actual mechanism of MDM2 involved in the control over VEGF transcription, we exposed the LNCaP and LNCaP-MST cells (MDM2 transfected) to hypoxia. Our experiments confirm that MDM2 activation can lead to significant decrease in the levels of p53 in MDM2 transfected LNCaP-MST cells than the wild-type LNCaP cells. The results further suggest that MDM2 can be a strong regulator of both p53 dependent and independent transcriptional activity. Similarly, an increased level of other transcription factors such as HIF-1α, P300, STAT3, pAKT and NF-κB was observed. As a point of convergence for many oncogenic signaling pathways, STAT3 is constitutively activated at high frequency in a wide diversity of cancers. Our results indicate that STAT3 can directly regulate VEGF expression that is controlled by MDM2. Furthermore, it is evident from our results that NF-κB may interfere with the transcriptional activity of p53, by downregulating its levels. On the other hand, several pro-angiogenic mechanisms, including VEGF transcription which is controlled by MDM2, seem to be mediated by NF-κB.

Male Breast Cancer: Current Scenario and Future Perspectives.

Male breast cancer (MBC), one of the rare types of cancer among men where the global incidence rate is 1.8% of all breast cancers cases with a yearly increase in a pace of 1.1%. Since the last 10 years, the incidence has been increased from 7.2% to 10.3% and the mortality rate was decreased from 11% to 3.8%. Nevertheless, the rate of diagnoses has been expected to be around 2.6% in the near future, still there is a great lack in studies to characterize the MBC including the developed countries. Based on our search, it is evidenced from the literature that the number of risk factors for the cause of MBC are significant, which includes the increase in age, family genetic history, mutations in specific genes due to various environmental impacts, hormonal imbalance and unregulated expression receptors for specific hormones of high levels of estrogen or androgen receptors compared to females. MBCs are broadly classified into ductal and lobular carcinomas with further sub-types, with some of the symptoms including a lump or swelling in the breast, redness of flaky skin in the breast, irritation and nipple discharge that is similar to the female breast cancer (FBC). The most common diagnostic tools currently in use are the ultrasound guided sonography, mammography, and biopsies. Treatment modalities for MBC include surgery, radiotherapy, chemotherapy, hormonal therapy, and targeted therapies. However, the guidelines followed for the diagnosis and treatment modalities of MBC are mostly based on FBC that is due to the lack of prospective studies related to MBC. However, there are distinct clinical and molecular features of MBC, it is a need to develop different clinical methods with more multinational approaches to help oncologist to improve care for MBC patients.

Bortezomib in Combination with Physachenolide C Reduces the Tumorigenic Properties of KRASmut/P53mut Lung Cancer Cells by Inhibiting c-FLIP.

BACKGROUND: Defects in apoptosis regulation are one of the classical features of cancer cells, often associated with more aggressiveness and failure to therapeutic options. We investigated the combinatorial antitumor effects of a natural product, physachenolide C (PCC) and bortezomib, in KRASmut/P53mut lung cancer cells and xenograft mice models. METHODS: The in vitro anticancer effects of the bortezomib and PCC combination were investigated using cell viability, migration, and invasion assays in 344SQ, H23, and H358 cell lines. Furthermore, the effects of combination treatment on the critical parameters of cellular metabolism, including extracellular acidification rate (ECAR) and mitochondrial oxidative phosphorylation based on the oxygen consumption rate of cancer cells were assessed using Seahorse assay. Finally, the antitumor effect of the bortezomib (1 mg/kg) and PCC (10 mg/kg) combination was evaluated using xenograft mice models. RESULTS: Our data showed that the bortezomib-PCC combination was more effective in reducing the viability of lung cancer cells in comparison with the individual treatments. Similarly, the combination treatment showed a significant inhibition of cell migration and invasion of cancer cells. Additionally, the key anti-apoptotic protein c-FLIP was significantly inhibited along with a substantial reduction in the key parameters of cellular metabolism in cancer cells. Notably, the bortezomib or PCC inhibited the tumor growth compared to the control group, the tumor growth inhibition was much more effective when bortezomib was combined with PCC in tumor xenograft mice models. CONCLUSION: These findings demonstrate that PCC sensitizes cancer cells to bortezomib, potentially improving the antitumor effects against KRASmut/P53mut lung cancer cells, with an enhanced efficacy of combination treatments without causing significant side effects.

Differential mechanisms involved in RG-7388 and Nutlin-3 induced cell death in SJSA-1 osteosarcoma cells.

Targeted therapy is becoming the mainstay of cancer treatment due to reduced side effects and enhanced tumor attack. In the last few decades, Murine Double Minute 2 (MDM2) protein has become one of the targets for developing cancer therapies. Blocking MDM2-p53 interaction has long been considered to offer a broad range of advantages during cancer treatment. In this study, we are reporting the differential mechanism of cell death induced by the two small-molecule inhibitors, named RG-7388 and Nutlin-3, that are specific for MDM2 in SJSA-1 Osteosarcoma cells (OS). Mechanistically, RG-7388 was able to enhance the phosphorylation of Mcl-1, which appears to significantly enhance its degradation, thereby relieving the pro-apoptotic protein Bak to execute the apoptosis mechanism. It was noted that the untreated SJSA-1 cells showed an accumulation of Mcl-1 levels, which was decreased following RG-7388 and to a lesser extent by Nutlin-3 and GSK-3ß (glycogen synthase kinase 3ß) inhibitor treatments. Additionally, we noted that CHIR-99021 (GSK-3ß inhibitor) blocked the cytotoxicity exerted by RG-7388 on SJSA-1 cells by decreasing Bak levels. Since Bak is an important pro-apoptotic protein, we hypothesized that phosphorylation of Mcl-1 by GSK-3ß could negatively impact the Mcl-1/Bak dimerization and relieve Bak to trigger the loss of mitochondrial membrane potential and thereby initiates apoptosis. We also observed that inhibition of GSK-3ß mediated reduction in Bak levels had a protective effect on the mitochondrial membrane integrity, and thus, caused a significant inhibition of the caspase-3 activity and PARP cleavage. Nutlin-3, on the other hand, appears to increase the levels of Bax, leading to the inactivation of Bcl-2, consequently loss of mitochondrial membrane potential and release of Cytochrome c (Cyt c) and elevation of Apaf-1 triggering apoptosis. Thus, to the best of our knowledge, this is the first study that delineates the differences in the molecular mechanism involving two MDM2 inhibitors triggering apoptosis through parallel pathways in SJSA-1 cells. This study further opens new avenues for the use of RG-7388 in treating osteosarcomas that often becomes resistant to chemotherapy due to Bcl-2 overexpression.

Anti-angiogenic and pro-apoptotic effects of a small-molecule JFD-WS in in vitro and breast cancer xenograft mouse models.

A small molecule that was developed for blocking vascular endothelial growth factor receptor 2 (VEGFR2) has been tested and confirmed for its anti-angiogenic activity. Subsequently, it was modified into a water soluble salt form (JFD-WS) to increase bioavailability and distribution during in vivo pre-clinical testing. The present study was designed to further evaluate the anti-angiogenic and pro-apoptotic effects of JFD-WS in monotherapy as well as in combination with paclitaxel (Taxol) using a mouse xenograft model. The in vitro anti-angiogenic effects of JFD-WS were investigated using cell proliferation, migration, Matrigel tube formation and VEGFR2 phosphorylation assays. The anti-angiogenic effect of JFD-WS was further established using chorioallantoic membrane (CAM) assay followed by in vivo efficacy testing on GI-101A breast adenocarcinoma cells. Pharmacokinetic and toxicity studies were performed using BALB/c mice. Finally, the apoptotic signals were assessed in the control and experimental tumor samples, and the plasma mucin 1 (MUC1) levels were analyzed. In the in vitro tests, JFD-WS effectively inhibited HUVEC proliferation, migration, tube formation and VEGFR2 phosphorylation. Additionally, JFD-WS inhibited the formation of blood vessels in chick chorioallantoic membrane. While inhibiting the xenograft tumor growth in experimental mice, JFD-WS decreased the plasma MUC1 levels. The western blot analysis of apoptotic markers and fragmentation analysis of DNA confirmed the pro-apoptotic effects of JFD-WS. These results indicated that JFD-WS alone or in combination with paclitaxel exerted antitumor and pro-apoptotic effects in the breast cancer xenograft model due to an anti-angiogenic effect. These results strongly support the clinical translation of its use.

MDM2 Overexpression Modulates the Angiogenesis-Related Gene Expression Profile of Prostate Cancer Cells.

The Murine Double Minute 2 (MDM2) amplification or overexpression has been found in many tumors with high metastatic and angiogenic ability. Our experiments were designed to explore the impact of MDM2 overexpression, specifically on the levels of angiogenesis-related genes, which can also play a major role in tumor propagation and increase its metastatic potential. In the present study, we have used the human angiogenesis RT² profiler PCR array to compare the gene expression profile between LNCaP and LNCaP-MST (MDM2 transfected) prostate cancer cells, along with LNCaP-MST cells treated with Nutlin-3, an MDM2 specific inhibitor. As a result of the overexpression of MDM2 gene in LNCaP-MST (10.3-fold), Thrombospondin 1 (THBS1), Tumor necrosis factor alpha (TNF-α) and Matrix metallopeptidase 9 (MMP9) were also found to be significantly up-regulated while genes such as Epiregulin (EREG), Tissue inhibitor of metalloproteinases 1 (TIMP1) were down-regulated. Also, we determined the total MMP activity and MMP9 expression in LNCaP, LNCaP-MST and SJSA-1 cells. Our results indicated that MDM2 level is positively correlated with MMP activity and MMP9 secretion. Our findings offer strong supporting evidence that MDM2 can impact growth and metastatic potential of cancer cells through tilting the balance towards pro-angiogenic mechanisms.

Apoptosis Induction by Ocimum sanctum Extract in LNCaP Prostate Cancer Cells.

Tulsi (Ocimum sanctum Linn), commonly known as "holy basil," has been used for the treatment of a wide range of ailments in many parts of the world. This study focuses on apoptosis-inducing ability of tulsi extract on prostate cancer cells. For this purpose LNCaP prostate cancer cells were treated with different concentrations of 70% ethanolic extract of tulsi (EET) and then the cytotoxicity was determined after 24 and 48 h. After treatment with EET externalization of phosphatidyl serine (PS) from the inner membrane to outer leaflet of the plasma membrane was clearly evidenced by the results obtained from both flow cytometry analysis with Annexin V-FITC and pSIVA-IANBD binding fluorescence microscopy assay. Depolarization of the mitochondrial membrane potential was also evidenced by the presence of 5,5',6,6'-tetrachlolo-1,1',3,3'-tetraethyl benzimedazolyl carbocyanine iodide (JC-1) monomeric form in the EET-treated cells that emitted the green fluorescence when compared with the control cells that emitted the red fluorescence due to aggregation of JC-1. Furthermore, the level of poly (ADP-ribose) polymerase (PARP) cleavage and Bcl-2 were determined using western blot analysis. When compared to the control cells the level of cleaved PARP was found to be higher with a concomitant decrease in the Bcl-2 level after 24 h of treatment of cells with EET. In addition, treatment with EET significantly elevated the activities of caspase-9 and caspase-3 in LNCaP cells compared with the control. Also, after 48 h of treatment all doses used in this study showed clear fragments of DNA, which is one of the hallmarks of apoptosis. Taken together, our findings suggest that, EET can effectively induce apoptosis in LNCaP cells via activation of caspase-9 and caspase-3 that can eventually lead to DNA fragmentation and cell death.

Induction of apoptosis in HeLa cells via caspase activation by resveratrol and genistein.

Selectively inducing apoptosis in cancer cells is a much desired strategy when tolerance toward side effects is minimal during chemotherapy. In our search for natural products that can induce apoptosis in human cervical cancer cells (HeLa), we selected resveratrol and genistein for our study. We conducted several experiments to test whether genistein can synergistically enhance the apoptotic potential of resveratrol at doses lower than the usual cytotoxic dose. Both resveratrol and genistein were able to induce apoptosis by enhancing the activities of caspase-9 and caspase-3 by themselves and also in combination. After 24 h of exposure to resveratrol and genistein, individually or in combination, lowered mitochondrial membrane potential was observed in HeLa cells. In addition, the mitochondrial membrane potential in HeLa cells was decreased, forcing JC-1 to stay in the monomeric form. The monomeric JC-1(5,5',6,6' -tetrachloro-1,1',3,3'-tetraethyl benzimedazolyl carbocyanine iodide) emitted green fluorescence. In the control group, the color of the fluorescence was red due to aggregation of JC-1 in the physiological pH. The treatment groups exhibited DNA fragmentation as the hallmark of apoptotic nuclear features. We also detected an obvious decrease in the level of HDM2 gene expression after both individual and combination treatments with resveratrol and genistein. Our findings suggest that resveratrol and genistein when combined can induce apoptosis at doses lower than usual doses, through the activation of caspases cascade, and by decreasing the expression of HDM2.

Phycocyanin induces apoptosis and enhances the effect of topotecan on prostate cell line LNCaP.

C-phycocyanin (C-PC) from Spirulina has been previously shown to have anticancer properties. Here, we report on anticancer activity of C-PC that was isolated from the novel cyanobacterium Limnothrix sp. 37-2-1. C-PC from this organism exhibited anticancer properties in our in vitro systems; however, the required doses were well above the range of anticancer drugs normally used. Therefore, we conducted several experiments to test whether lower-than-usual doses of the anticancer drug topotecan (TPT) can offer the same level of cytotoxic effects as normal doses when combined with C-PC. For this purpose, cytotoxicities of C-PC and TPT were tested using the LNCaP (prostate cancer) cells. We found that when only 10% of a typical dose of TPT was combined with C-PC, the cancer cells were killed at a higher rate than when TPT was used alone at full dose. Similarly, we were also able to detect an increased level of radical oxygen species (ROS) generation as well as an increase in activities of caspase-9 and caspase-3 when these two compounds were used in combination. Taken together, our findings suggest that combining C-PC from Limnothrix sp. with the lower dose of TPT can induce apoptosis through generation of ROS and activation of caspases. In that respect, we suggest that C-PC can potentially improve the efficacy of the currently available anticancer drug, and therefore diminish its harsh side effects in the patient.

Bromelain-induced apoptosis in GI-101A breast cancer cells.

Bromelain is a proteolytic enzyme extracted from the stems and the immature fruits of pineapple that was found to be antitumorigenic in different in vitro models. Bromelain has been reported to promote apoptosis, particularly in breast cancer cells, with the up-regulation of c-Jun N-terminal kinase and p38 kinase. Our study was designed to determine if bromelain could induce apoptosis in GI-101A breast cancer cells. GI-101A cells were treated with increasing concentrations of bromelain for 24 hours. The effect of bromelain for inducing cell death via activation of the apoptosis mechanism in GI-101A cells was further determined by using caspase-9 and caspase-3 assays along with the M30-Apoptosense assay to measure cytokeratin 18 (CK18) levels in the cytoplasm of the cultured cancer cells. A dose-dependent increase in the activities of caspase-9 and caspase-3 coinciding with elevation of CK18 levels was found in bromelain-treated cells compared with control cells. Furthermore, the apoptosis induction by bromelain was confirmed by DNA fragmentation analysis and 4,6'-diamino-2-phenylindole dihydrochloride fluorescence staining of the nucleus. Our results indicate an increase in apoptosis-related cell death in breast cancer cells with increasing concentrations of bromelain.