Upregulation Of Death Receptor Research Articles

Gintonin-Enriched Panax ginseng Extract Fraction Sensitizes Renal Carcinoma Cells to TRAIL-Induced Apoptosis through DR4/5 Upregulation.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising chemotherapeutic agent because of its selective apoptotic action on cancer cells. However, resistance to TRAIL-induced apoptosis remains a challenge in many cancers. The gintonin-enriched Panax ginseng extract fraction (GEF) has diverse pharmacological benefits. We explored the combined efficacy of GEF and TRAIL in inducing apoptosis in human renal cell carcinoma (RCC) cells. The effect of GEF treatment on the viability, clonogenic potential, wound healing, and TRAIL-induced apoptotic signaling of RCC cells was studied in vitro. Our investigation revealed that GEF pre-treatment sensitized RCC cells to TRAIL-induced apoptosis, as evidenced by DNA fragmentation and cell proliferation, colony formation, and migration inhibition. This sensitization was linked to the upregulation of death receptors 4 and 5 and alterations in apoptotic protein expression, notably, the decreased expression of the Mu-2-related death-inducing gene, a novel anti-apoptotic protein. Our findings underscore the necessity of caspase activation for GEF/TRAIL-induced apoptosis using the pan-caspase inhibitor Z-VAD-FMK. This study demonstrates that GEF sensitizes human RCC cells to TRAIL-induced apoptosis by upregulating DR4/5 and modulating apoptotic protein expression. These findings suggest a promising strategy for overcoming TRAIL resistance in cancer therapy and highlight the potential of GEF as a valuable adjunct to TRAIL-based treatments.

Selective killing of castration-resistant prostate cancer cells by formycin A via the ATF4-CHOP axis.

Prostate cancer is initially androgen-dependent but often relapses to an androgen-independent state called castration-resistant prostate cancer (CRPC). Currently approved therapies have limited efficacy against CRPC, highlighting the need for novel therapeutic strategies. To address this need, we conducted a drug screen in our previously established aggressive CRPC cell model. We found that formycin A induced cell death in CRPC model cells but not in parental prostate cancer cells. In addition, formycin A upregulated death receptor 5 through the induction of endoplasmic reticulum stress, activating the "extrinsic" apoptosis pathway in CRPC model cells. Moreover, formycin A showed invivo antitumor efficacy against CRPC xenografts in castrated nude mice. Thus, our findings highlight the potential of formycin A as a CRPC therapeutic.

Colon Cancer Cells Treated with Lacticaseibacillus casei Undergo Apoptosis and Release DAMPs Indicative of Immunogenic Cell Death.

Probiotic bacteria, and especially lactic acid bacteria, have long been known to wield a variety of health-beneficial effects, including antioxidant, antimicrobial, anti-inflammatory, immunomodulatory, and anticancer activities. However, our understanding of the mechanisms involved in these activities remains incomplete. In this study, we wished to investigate the processes that give rise to the anticancer activity of Lacticaseibacillus casei ATCC393 and the possibility that immunogenic cell death of cancer cells can be induced following treatment with this probiotic. In both cell lines that we have examined, we detected notable pro-apoptotic signaling, including the upregulation of death receptors, that culminated in the activation of caspase 3, the endpoint and most characteristic effector molecule of all pro-apoptotic cascades. In addition, we identified damage-associated molecular patterns associated with immunogenic cell death. Calreticulin exposure on the outer cell membrane, HMGB1 translocation outside the nucleus and depletion of intracellular ATP was evident in both cancer cell lines treated with the probiotic, while expression of type I interferons was upregulated in CT26 cells. Our findings suggest that treatment with the probiotic induced apoptosis in cancer cells, mediated by extrinsic death receptor signaling. Moreover, it resulted in the release of molecular signals related with immunogenic cell death and induction of cancer cell-specific adaptive immune responses.

Apoptosis of Pancreatic Cancer Cells after Co-Treatment with Eugenol and Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand.

Pancreatic cancer is a refractory cancer with limited treatment options. Various cancer types are resistant to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Eugenol, the main component of clove oil, exhibits anticancer, anti-inflammatory, and antioxidant effects. However, no studies have reported that eugenol increases TRAIL sensitivity by upregulating death receptor (DR) expression. Here, we aimed to investigate eugenol as a potent TRAIL sensitizer. Increased apoptosis and inhibition of cell proliferation was observed in pancreatic cancer cells treated with eugenol and TRAIL compared with those treated with eugenol alone. Eugenol upregulated the expression of DR5, inhibited the FLICE-inhibitory protein (FLIP), an anti-apoptotic protein, and increased p53, a tumor suppressor protein. In addition, eugenol induced the generation of reactive oxygen species (ROS) and caused endoplasmic reticulum (ER) stress. C/EBP-homologous protein (CHOP) knockdown using siRNA decreased the expression of DR5 and reduced the combined effects of eugenol and TRAIL. These results demonstrate that eugenol enhances TRAIL-induced apoptosis by upregulating DR5 through the ROS-mediated ER stress-CHOP pathway, which enhances ER stress by inducing p53 and downregulating FLIP expression. This suggests that eugenol has the potential to treat pancreatic cancer by increasing cell sensitivity to TRAIL.

Acquired Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) Resistance of Human Colorectal Cancer Cells Is Linked to Histone Acetylation and Is Synergistically Ameliorated by Combination with HDAC Inhibitors.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an attractive target for the treatment of various malignancies; however, its therapeutic potential is limited because of the frequent occurrence of tumor cell resistance. In this study, we determined whether TRAIL resistance acquired by repeated administration could be overcome by HDAC inhibition in human colorectal cancer cells. TRAIL-resistant HCT116 human colorectal cancer cells (HCT116-TR) were generated by repeated treatment with 10 and 25 ng/mL TRAIL twice weekly for 28 days. The resulting TRAIL-resistant cells were noncross-resistant to other chemotherapeutic agents. The levels of histone acetylation-related proteins, such as ac-histone H4 and HDAC1, were altered in HCT116-TR cells compared with the parental HCT116 cell line. The combined treatment with TRAIL and HDAC inhibitors significantly increased apoptosis in HCT116-TR cells and indicated a synergistic effect. The mechanism by which HDAC inhibition sensitizes HCT116-TR cells to TRAIL is dependent on the intrinsic pathway. In addition, we found that HDAC inhibition enhanced the sensitivity of cells to TRAIL through mitogen-activated protein kinases/CCAAT/enhancer-binding protein homologs of protein-dependent upregulation of death receptor 5. These results suggest that histone acetylation is responsible for acquired TRAIL resistance after repeated exposure and acquired resistance to TRAIL may be overcome by combination therapies with HDAC inhibitors.

Licochalcone D exhibits cytotoxicity in breast cancer cells and enhances tumor necrosis factor‐related apoptosis‐inducing ligand‐induced apoptosis through upregulation of death receptor 5

AbstractAnticancer strategies using natural products or derivatives are promising alternatives for cancer treatment. Here, we showed that licochalcone D (LCD), a natural flavonoid extracted from Glycyrrhiza uralensis Fisch, suppressed the growth of breast cancer cells, and was less toxic to MCF‐10A normal breast cells. LCD‐induced DNA damage, cell cycle arrest, and apoptosis in breast cancer cells. Furthermore, LCD potentiated tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL)‐induced cytotoxicity. Mechanistically, LCD was revealed to reduce survival protein expression and to upregulate death receptor 5 (DR5) expressions. Silencing DR5 blocked the ability of LCD to sensitize cells to TRAIL‐mediated apoptosis. LCD increased CCAAT/enhancer‐binding protein homologous protein (CHOP) expression in breast cancer cells. Knockdown of CHOP attenuated DR5 upregulation and apoptosis triggered by cotreatment with LCD and TRAIL. Furthermore, LCD suppressed the phosphorylation of extracellular signal‐regulated kinase and promoted the phosphorylation of c‐Jun amino‐terminal kinase (JNK) and p38 mitogen‐activated protein kinase (MAPK). Pretreatment with JNK inhibitor SP600125 or p38 MAPK inhibitor SB203580 abolished the upregulation of DR5 and CHOP, and also attenuated LCD plus TRAIL‐induced cleavage of poly(ADP‐ribose) polymerase. Overall, our results show that LCD exerts cytotoxic effects on breast cancer cells and arguments TRAIL‐mediated apoptosis by inhibiting survival protein expression and upregulating DR5 in a JNK/p38 MAPK‐CHOP‐dependent manner.

Dabrafenib alleviates hepatotoxicity caused by lenvatinib via inhibiting the death receptor signaling pathway

Lenvatinib is a multi-target inhibitor that exerts anti-tumor effects by inhibiting angiogenesis and is now commonly used as a first-line treatment for hepatocellular carcinoma. However, with the widespread use of lenvatinib, the problem of serious and fatal hepatotoxicity has become increasingly prominent. Currently, the mechanism behind this toxicity is not yet understood, and as a result, there is a lack of safe and effective intervention strategies with minimal side effects. Here, we established the model of lenvatinib-induced liver injury in vivo and in vitro and found that lenvatinib caused hepatotoxicity by inducing apoptosis. Further mechanistic studies in cellular models revealed that lenvatinib upregulated death receptor signaling pathway, which activated the downstream effector Caspase-8, and ultimately led to apoptosis. Meanwhile, lenvatinib-induced apoptosis was associated with ROS generation and DNA damage. In addition, after screening marketed drugs and natural products in combination with cellular modeling, we identified a potential co-administered drug, dabrafenib, which could alleviate lenvatinib-induced hepatotoxicity. Further mechanistic studies revealed that dabrafenib attenuated lenvatinib-induced hepatotoxicity by inhibiting the activation of the death receptor signaling pathway. Subsequently, cancer cell proliferation assays confirmed that dabrafenib did not antagonize the antitumor effects of lenvatinib. In conclusion, our results validate that apoptosis caused by the death receptor signaling pathway is the key cause of lenvatinib-induced hepatotoxicity, and dabrafenib alleviates lenvatinib-induced hepatotoxicity by inhibiting this pathway.

Targeting Integrin α3 Blocks β1 Maturation, Triggers Endoplasmic Reticulum Stress, and Sensitizes Glioblastoma Cells to TRAIL-Mediated Apoptosis.

Glioblastoma (GBM) is a devastating brain cancer for which new effective therapies are urgently needed. GBM, after an initial response to current treatment regimens, develops therapeutic resistance, leading to rapid patient demise. Cancer cells exhibit an inherent elevation of endoplasmic reticulum (ER) stress due to uncontrolled growth and an unfavorable microenvironment, including hypoxia and nutrient deprivation. Cancer cells utilize the unfolded protein response (UPR) to maintain ER homeostasis, and failure of this response promotes cell death. In this study, as integrins are upregulated in cancer, we have evaluated the therapeutic potential of individually targeting all αβ1 integrin subunits using RNA interference. We found that GBM cells are uniquely susceptible to silencing of integrin α3. Knockdown of α3-induced proapoptotic markers such as PARP cleavage and caspase 3 and 8 activation. Remarkably, we discovered a non-canonical function for α3 in mediating the maturation of integrin β1. In its absence, generation of full length β1 was reduced, immature β1 accumulated, and the cells underwent elevated ER stress with upregulation of death receptor 5 (DR5) expression. Targeting α3 sensitized TRAIL-resistant GBM cancer cells to TRAIL-mediated apoptosis and led to growth inhibition. Our findings offer key new insights into integrin α3's role in GBM survival via the regulation of ER homeostasis and its value as a therapeutic target.

Expression of Concern: microRNA-7 upregulates death receptor 5 and primes resistant brain tumors to caspase-mediated apoptosis.

Expression of Concern: microRNA-7 upregulates death receptor 5 and primes resistant brain tumors to caspase-mediated apoptosis.

Cyclizine induces cytotoxicity and apoptosis in macrophages through the extrinsic and intrinsic apoptotic pathways.

Cyclizine, an over-the-counter and prescription antihistamine, finds widespread application in the prevention and treatment of motion sickness, encompassing symptoms such as nausea, vomiting, dizziness, along with its effectiveness in managing vertigo. However, the overuse or misuse of cyclizine may lead to hallucinations, confusion, tachycardia, and hypertension. The molecular mechanisms underlying cyclizine-induced cytotoxicity and apoptosis remain unclear. During the 24 h incubation duration, RAW264.7 macrophages were exposed to different concentrations of cyclizine. Cytotoxicity was assessed through the lactate dehydrogenase assay. Flow cytometry employing annexin V-fluorescein isothiocyanate and propidium iodide was utilized to evaluate apoptosis and necrosis. Caspase activity and mitochondrial dysfunction were evaluated through a fluorogenic substrate assay and JC-1 dye, respectively. Flow cytometry employing fluorogenic antibodies was utilized to evaluate the release of cytochrome c and expression of death receptor, including tumor necrosis factor-α receptor and Fas receptor. Western blotting was utilized to evaluate the expression of the Bcl2 and Bad apoptotic regulatory proteins. The findings unveiled from the present study demonstrated that cyclizine exerted a concentration-dependent effect on RAW264.7 macrophages, leading to the induction of cytotoxicity, apoptosis, and necrosis. This compound further activated the intrinsic apoptotic pathway by inducing mitochondrial dysfunction, Bcl2/Bad exchange expression, cytochrome c liberation, and activation of caspases contained caspase 3, 8, and 9. Moreover, the activation of the extrinsic apoptotic pathway was observed as cyclizine induced the upregulation of death receptors and increased caspase activities. Based on our investigations, it can be inferred that cyclizine prompts cytotoxicity and apoptosis in RAW264.7 macrophages in a concentration-dependent manner by triggering both the intrinsic and extrinsic apoptotic pathways.

Silibinin, a potential fasting mimetic, inhibits hepatocellular carcinoma by triggering extrinsic apoptosis.

Fasting, without inducing malnutrition, has been shown to have various beneficial effects, including the inhibition of tumor initiation and progression. However, prolonged fasting poses challenges for many cancer patients, particularly those in intermediate and terminal stages. Thus, there is an urgent need for the development of fasting mimetics which harness the protective effects of fasting but more suitable for patients. In this study, we first highlighted the pivotal role of silibinin in AMP-activated protein kinase (AMPK) pathway and may serve, as a potential fasting mimetic via screening hepatoprotective drugs. Further metabolic analysis showed that silibinin inhibited the adenosine triphosphate (ATP) levels, glucose uptake and diminished glycolysis process, which further confirmed that silibinin served as a fasting mimetic. In addition, fasting synergized with silibinin, or used independently, to suppress the growth of hepatocellular carcinoma (HCC) in vivo. Mechanistically, silibinin upregulated death receptor 5 (DR5) through AMPK activation, and thus promoting extrinsic apoptosis and inhibiting HCC growth both in vitro and in vivo. Inhibition of AMPK using small interfering RNA (siRNA) or compound C, an AMPK inhibitor, significantly attenuated the upregulation of DR5 and the apoptotic response induced by silibinin. These findings suggest that silibinin holds promise as a fasting mimetic and may serve as an adjuvant drug for HCC treatment.

TRAIL-Sensitizing Effects of Flavonoids in Cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) represents a promising anticancer agent, as it selectively induces apoptosis in transformed cells without altering the cellular machinery of healthy cells. Unfortunately, the presence of TRAIL resistance mechanisms in a variety of cancer types represents a major hurdle, thus limiting the use of TRAIL as a single agent. Accumulating studies have shown that TRAIL-mediated apoptosis can be facilitated in resistant tumors by combined treatment with antitumor agents, ranging from synthetic molecules to natural products. Among the latter, flavonoids, the most prevalent polyphenols in plants, have shown remarkable competence in improving TRAIL-driven apoptosis in resistant cell lines as well as tumor-bearing mice with minimal side effects. Here, we summarize the molecular mechanisms, such as the upregulation of death receptor (DR)4 and DR5 and downregulation of key anti-apoptotic proteins [e.g., cellular FLICE-inhibitory protein (c-FLIP), X-linked inhibitor of apoptosis protein (XIAP), survivin], underlying the TRAIL-sensitizing properties of different classes of flavonoids (e.g., flavones, flavonols, isoflavones, chalcones, prenylflavonoids). Finally, we discuss limitations, mainly related to bioavailability issues, and future perspectives regarding the clinical use of flavonoids as adjuvant agents in TRAIL-based therapies.

Synergistic antitumor effects of circularly permuted TRAIL with doxorubicin in triple-negative breast cancer.

Circularly permuted TRAIL (CPT), a novel recombinant TRAIL mutant, is a potent antitumor agent. However, its efficacy in triple-negative breast cancer (TNBC) remains unclear. Treatment with CPT alone and in combination with doxorubicin (Dox) is explored for its effects on the proliferation and apoptosis of MDA-MB-231 (MB231) and MDA-MB-436 (MB436) breast cancer cells in vitro and in vivo. Here, we show that CPT combined with Dox exhibits time- and dose-dependent synergy to inhibit cell viability and enhance apoptosis of MB231 and MB436 cells. Combined treatment substantially increases caspase-8, caspase-3, and PARP cleavage in both cell lines and significantly suppresses tumor growth in nude mice bearing MB231 xenografts. Collectively, our findings demonstrate that treatment with CPT in combination with Dox exerts synergistic antitumor effects through activation of the caspase cascade pathway, a mechanism that is partly dependent on the Dox-induced upregulation of death receptor 4 and death receptor 5. Therefore, CPT combined with Dox may be a feasible therapeutic strategy for the management of TNBC.

Combination treatment of bortezomib and epirubicin increases the expression of TNFRSF10 A/B, and induces TRAIL-mediated cell death in colorectal cancer cells

Colorectal cancer is one of the most common cancers worldwide, affecting the colon and rectum. A major problem in the treatment of colorectal cancer is acquired chemoresistance, including resistance against death receptor-induced apoptosis. Therefore, investigating new biomarkers for the treatment of the disease and sensitization strategies against TRAIL might be of high clinical importance. TNFRSF10A/B are known as death receptors for TRAIL-induced apoptotic cell death. In this study, we used multiple bioinformatic tools and experimental analyses to investigate the role of TRAIL receptors TNFRSF10A and TNFRSF10B in colorectal cancer. We also identified the potential effect of bortezomib and epirubicin in the induction of TRAIL-mediated apoptotic cell death. Here, we showed that TNFRSF10 A/B expressions are upregulated in various tumor types, including COAD, and its high expression is decreased with the different clinicopathological parameters in COAD. We also found an association between TNFRSF10 A/B expression and tumor molecular subtypes. We further detected the association between the expression of TNFRSF10 A/B and immune cell tumor infiltration, including B cells, CD8+ T cells, neutrophils and dendritic cells. In addition, we showed that combining bortezomib and epirubicin treatment leads to the upregulation of TNFRSF10 A/B in colorectal cancer cells in vitro. The increase in the expression of death receptors was correlated with higher active caspase-3 levels following the incubation of cells with recombinant TRAIL protein, which is a ligand for TNFRSF10 A/B receptors. Our results suggest that TNFRSF10 A/B may be a marker to differentiate tumor molecular subtypes in colorectal cancer. The expression of TNFRSF10 A/B may be associated with the recruitment of immune cells into tumors and the development of tumor suppression. The combination of bortezomib and epirubicin treatment might sensitize colorectal cancer cells to TRAIL-induced apoptosis via the upregulation of death receptor.

Hyperthermia maintains death receptor expression and promotes TRAIL-induced apoptosis.

Tumor necrosis factor-related apoptosis-inducing ligand activates apoptotic pathways and could potentially be used in anticancer treatments. However, oral squamous cell carcinoma cells are known to be resistant to tumor necrosis factor-related apoptosis-inducing ligand-induced cell death. It has been previously reported that hyperthermia upregulates tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in other cancers. As such, we evaluated whether hyperthermia upregulates tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in a tumor necrosis factor-related apoptosis-inducing ligand-resistant oral squamous cell carcinoma cell line. The oral squamous cell carcinoma cell line HSC3 was cultured and divided into hyperthermia and control groups. We investigated the antitumor effects of recombinant human tumor necrosis factor-related apoptosis-inducing ligand using cell proliferation and apoptosis assays. Additionally, we measured death receptor 4 and 5 levels, and determined death receptor ubiquitination status, as well as E3 ubiquitin ligase targeting of death receptor in both hyperthermia and control groups before recombinant human tumor necrosis factor-related apoptosis-inducing ligand administration. Treatment with recombinant human tumor necrosis factor-related apoptosis-inducing ligand produced greater inhibitory effects in the hyperthermia group than in the control group. Moreover, death receptor protein expression in the hyperthermia group was upregulated on the cell surface (and overall), although death receptor mRNA was downregulated. The half-life of death receptor was several hours longer in the hyperthermia group; concomitantly, E3 ubiquitin ligase expression and death receptor ubiquitination were downregulated in this group. Our findings suggested that hyperthermia enhances apoptotic signaling by tumor necrosis factor-related apoptosis-inducing ligand via the suppression of death receptor ubiquitination, which upregulates death receptor expression. These data suggest that the combination of hyperthermia and tumor necrosis factor-related apoptosis-inducing ligand has implications in developing a novel treatment strategy for oral squamous cell carcinoma.

Radiation therapy improves CAR T cell activity in acute lymphoblastic leukemia

Autologous T cells engineered to express a chimeric antigen receptor (CAR) specific for CD19 are approved for the treatment of various CD19+ hematological malignancies. While CAR T cells induce objective responses in a majority of patients, relapse frequently occurs upon loss of CD19 expression by neoplastic cells. Radiation therapy (RT) has been successfully employed to circumvent the loss of CAR targets in preclinical models of pancreatic cancer. At least in part, this reflects the ability of RT to elicit death receptor (DR) expression by malignant cells, enabling at least some degree of CAR-independent tumor killing. In a human model of CD19+ acute lymphoblastic leukemia (ALL), we also observed DR upregulation by RT, both in vitro and in vivo. Moreover, low-dose total body irradiation (LD-TBI) delivered to ALL-bearing mice prior to CAR T cell infusion considerably extended the overall survival benefit afforded by CAR T cells alone. Such an improved therapeutic activity was accompanied by a superior expansion of CAR T cells in vivo. These data encourage the initiation of clinical trials combining LD-TBI with CAR T cells in patients with hematological malignancies.

DHA Induces Cell Death through the Production of ROS and the Upregulation of CHOP in Fibroblast-like Synovial Cells from Human Rheumatoid Arthritis Patients.

Rheumatoid arthritis (RA) is an inflammatory disease marked by a massive proliferation of synovial cells in the joints. In this study, we investigated the pro-apoptotic effects of docosahexaenoic acid (DHA) in human fibroblast-like synovial cells from RA patients (RA-FLS). An in vitro study using MH7A cells showed that DHA treatment induced caspase-8-dependent apoptosis in a dose-dependent manner and reduced the TNF-α-mediated induction of MMP-9 and IL-1β. DHA also induced the phosphorylation of eIF2α, the expression of the ER stress markers ATF4 and C/EBP homologous protein (CHOP), and death receptor 5 (DR5). The knockdown of CHOP or DR5 increased cell viability and reduced apoptosis in DHA-treated cells. Furthermore, the knockdown of CHOP reduced DHA-mediated DR5 expression, while the overexpression of CHOP increased DR5 expression. We also found that DHA treatment induced the accumulation of reactive oxygen species (ROS), and pretreatment with the anti-oxidant Tiron effectively abrogated not only the expression of CHOP and DR5, but also DHA-induced apoptosis. Under this condition, cell viability was increased, while PARP-1 cleavage and caspase-8 activation were reduced. All the findings were reproduced in human primary synovial cells obtained from RA patients. These results suggest that the DHA-mediated induction of ROS and CHOP induced apoptosis through the upregulation of DR5 in RA-FLSs, and that CHOP could be used as a therapy for RA.

DR5 Up-Regulation Induced by Dichloroacetate Sensitizes Tumor Cells to Lipid Nanoparticles Decorated with TRAIL.

Cancer resistance to treatments is a challenge that researchers constantly seek to overcome. For instance, TNF-related apoptosis-inducing ligand (TRAIL) is a potential good prospect as an anti-cancer therapy, as it attacks tumor cells but not normal cells. However, treatments based in soluble TRAIL provided incomplete clinical results and diverse formulations have been developed to improve its bioactivity. In previous works, we generated a new TRAIL formulation based in its attachment to the surface of unilamellar nanoliposomes (LUV-TRAIL). This formulation greatly increased apoptosis in a wide selection of tumor cell types, albeit a few of them remained resistant. On the other hand, it has been described that a metabolic shift in cancer cells can also alter its sensitivity to other treatments. In this work, we sought to increase the sensitivity of several tumor cell types resistant to LUV-TRAIL by previous exposure to the metabolic drug dichloroacetate (DCA), which forces oxidative phosphorylation. Results showed that DCA + LUV-TRAIL had a synergistic effect on both lung adenocarcinoma A549, colorectal HT29, and breast cancer MCF7 cells. Despite DCA inducing intracellular changes in a cell-type specific way, the increase in cell death by apoptosis was clearly correlated with an increase in death receptor 5 (DR5) surface expression in all cell lines. Therefore, DCA-induced metabolic shift emerges as a suitable option to overcome TRAIL resistance in cancer cells.

Modulation of Spheroid Forming Capacity and TRAIL Sensitivity by KLF4 and Nanog in Gastric Cancer Cells.

The expression of pluripotency factors, and their associations with clinicopathological parameters and drug response have been described in various cancers, including gastric cancer. This study investigated the association of pluripotency factor expression with the clinicopathological characteristics of gastric cancer patients, as well as changes in the expression of these factors upon the stem cell-enriching spheroid culture of gastric cancer cells, regulation of sphere-forming capacity, and response to cisplatin and TRAIL treatments by Nanog and KLF4. Nanog expression was significantly associated with the emergence of a new tumor and a worse prognosis in gastric cancer patients. The expression of the pluripotency factors varied among six gastric cancer cells. KLF4 and Nanog were expressed high in SNU-601, whereas SOX2 was expressed high in SNU-484. The expression of KLF4 and SOX2 was increased upon the spheroid culture of SNU-601 (KLF4/Nanog-high) and SNU-638 (KLF4/Nanog-low). The spheroid culture of them enhanced TRAIL-induced viability reduction, which was accompanied by the upregulation of death receptors, DR4 and DR5. Knockdown and overexpression of Nanog in SNU-601 and SNU-638, respectively, did not affect spheroid-forming capacity, however, its expression was inversely correlated with DR4/DR5 expression and TRAIL sensitivity. In contrast, KLF4 overexpression in SNU-638 increased spheroid formation, susceptibility to cisplatin and TRAIL treatments, and DR4/DR5 expression, while the opposite was found in KLF4-silenced SNU-601. KLF4 is supposed to play a critical role in DR4/DR5 expression and responses to TRAIL and cisplatin, whereas Nanog is only implicated in the former events only. Direct regulation of death receptor expression and TRAIL response by KLF4 and Nanog have not been well documented previously, and the regulatory mechanism behind the process remains to be elucidated.

Effects of Curcumin and Lactoferrin to Inhibit the Growth and Migration of Prostatic Cancer Cells.

Prostate cancer remains one of the main causes of death for men worldwide. Despite recent advances in cancer treatment, patients develop resistance after an initial period of optimal efficacy. Nowadays, it is accepted that natural compounds can result in health benefits with a preventive or adjuvant effect. The purpose of this study was to evaluate the effects of curcumin (CU), a bioactive compound in the spice turmeric, and lactoferrin (LF), a natural glycoprotein with immunomodulatory properties, on DU145 and PC3. Prostate cancer cells were cultured with and without LF (175 μM) and CU (2.5 μg/mL and 5 μg/mL), alone and in combination. Cell viability, migration ability, death receptors (DRs), and integrins (α3, β1) gene expression were evaluated, as well as human annexin V quantification and Akt phosphorylation. Differences among cells group, defined according to the treatment used, were assessed with ANOVA. The results showed that the effects of CU and LF are different between the two prostatic cell lines analyzed. In DU145, a reduction in cell proliferation and migration is reported both in the presence of single and combined treatments. In PC3 cells, there is a significant reduction in proliferation in the presence of CU alone, while the inhibition of migration is mainly related to the LF treatment and its combination with CU, compared to untreated cells. Moreover, the reduction in gene expression of integrins and Akt pathway activation were observed mostly in the presence of the CU and LF combination, including the upregulation of DR and annexin V levels, with greater significance for the DU145 cells. In conclusion, our results suggest that CU and LF may have a potentially beneficial effect, mainly when administered in combination, leading to a reduction in cancer cells' aggressiveness.