Sorafenib enhances pemetrexed cytotoxicity through an autophagy-dependent mechanism in cancer cells

Pharmacogenomic insights: IL-23R and ATG-10 polymorphisms in Sorafenib response for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Sorafenib is the first FDA-approved systemic therapy for advanced HCC. This study investigates the influence of IL-23R (rs7517847) and ATG-10 (rs10514231) genetic polymorphisms on Sorafenib response, survival outcomes, average tolerable dose, and adverse events. This prospective open-label cohort study included 100 HCC patients, assessing IL-23R and ATG-10 genotypes via real-time polymerase chain reaction (RT-PCR). Patient's responses were evaluated using modified RECIST criteria. Statistical analyses evaluated the association of genetic variants with response, progression-free survival (PFS), overall survival (OS), average tolerable Sorafenib dose, and adverse events. IL-23R TT carriers had the highest Sorafenib response rate (80%) compared to GT (13.3%) and GG (6.7%) (P = 0.021), while ATG-10 TT carriers had a 13.9-fold increased response likelihood (P = 0.001). The T allele in ATG-10 significantly predicted longer PFS (P = 0.025) and OS (P = 0.011), suggesting a potential prognostic role. IL-23R GG carriers received significantly higher Sorafenib doses than TT (P = 0.0174) and GT (P = 0.0227), whereas ATG-10 had no effect on dosage. However, its CT genotype was significantly associated with a higher risk of Hand-Foot Syndrome (P = 0.012), and independent of dose (P = 0.0018). IL-23R and ATG-10 polymorphisms influence Sorafenib response, survival, and tolerability in HCC patients. Genetic screening may improve personalized treatment strategies by optimizing Sorafenib efficacy and minimizing toxicity.This trial was registered on clinicaltrials.gov with registration number NCT06030895, registered on "September 11th, 2023," retrospectively.

Autophagy-based therapy for hepatocellular carcinoma: from standard treatments to combination therapy, oncolytic virotherapy, and targeted nanomedicines

Human hepatocellular carcinoma (HCC) has been identified as a significant cause of mortality worldwide. In recent years, extensive research has been conducted to understand the underlying mechanisms of autophagy in the pathogenesis of the disease, with the aim of developing novel therapeutic agents. Targeting autophagy with conventional therapies in invasive HCC has opened up new opportunities for treatment. However, the emergence of resistance and the immunosuppressive tumor environment highlight the need for combination therapy or specific targeting, as well as an efficient drug delivery system to ensure targeted tumor areas receive sufficient doses without affecting normal cells or tissues. In this review, we discuss the findings of several studies that have explored autophagy as a potential therapeutic approach in HCC. We also outline the potential and limitations of standard therapies for autophagy modulation in HCC treatment. Additionally, we discuss how different combination therapies, nano-targeted strategies, and oncolytic virotherapy could enhance autophagy-based HCC treatment in future research.

Autophagy in cancer immunotherapy: Perspective on immune evasion and cell death interactions

Both the innate and adaptive immune systems work together to produce immunity. Cancer immunotherapy is a novel approach to tumor suppression that has arisen in response to the ineffectiveness of traditional treatments like radiation and chemotherapy. On the other hand, immune evasion can diminish immunotherapy's efficacy. There has been a lot of focus in recent years on autophagy and other underlying mechanisms that impact the possibility of cancer immunotherapy. The primary feature of autophagy is the synthesis of autophagosomes, which engulf cytoplasmic components and destroy them by lysosomal degradation. The planned cell death mechanism known as autophagy can have opposite effects on carcinogenesis, either increasing or decreasing it. It is autophagy's job to maintain the balance and proper functioning of immune cells like B cells, T cells, and others. In addition, autophagy controls whether macrophages adopt the immunomodulatory M1 or M2 phenotype. The ability of autophagy to control the innate and adaptive immune systems is noteworthy. Interleukins and chemokines are immunological checkpoint chemicals that autophagy regulates. Reducing antigen presentation to induce immunological tolerance is another mechanism by which autophagy promotes cancer survival. Therefore, targeting autophagy is of importance for enhancing potential of cancer immunotherapy.

An ATG4B inhibitor blocks autophagy and Sensitizes Sorafenib Inhibition Activities in HCC tumor cells

Autophagy related 4B (ATG4B) which regulates autophagy by promoting the formation of autophagosome through reversible modification of LC3, is closely related to cancer cell growth and drug resistance, and therefore is an attractive therapeutic target. Recently, ATG4B inhibitors have been reported, yet with drawbacks including weak potency. To discover more promising ATG4B inhibitors, we developed a high-throughput screening (HTS) assay and identified a new ATG4B inhibitor named DC-ATG4in. DC-ATG4in directly binds to ATG4B and inhibits its enzyme activity with an IC₅₀ of 3.08 ± 0.47 μM. We further confirmed that DC-ATG4in is an autophagy inhibitor and blocks autophagy induced by Sorafenib in Hepatocellular Carcinoma (HCC) cells. More importantly, combination of DC-ATG4in with Sorafenib synergized the cancer cell killing effect and proliferation inhibition activities on HCC cells. Our data suggested that inactivation of autophagy via ATG4B inhibition may be a viable strategy to sensitize existing targeted therapy such as Sorafenib in the future.

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.

Small Molecule Inhibitors for Hepatocellular Carcinoma: Advances and Challenges

According to data provided by World Health Organization, hepatocellular carcinoma (HCC) is the sixth most common cause of deaths due to cancer worldwide. Tremendous progress has been achieved over the last 10 years developing novel agents for HCC treatment, including small-molecule kinase inhibitors. Several small molecule inhibitors currently form the core of HCC treatment due to their versatility since they would be more easily absorbed and have higher oral bioavailability, thus easier to formulate and administer to patients. In addition, they can be altered structurally to have greater volumes of distribution, allowing them to block extravascular molecular targets and to accumulate in a high concentration in the tumor microenvironment. Moreover, they can be designed to have shortened half-lives to control for immune-related adverse events. Most importantly, they would spare patients, healthcare institutions, and society as a whole from the burden of high drug costs. The present review provides an overview of the pharmaceutical compounds that are licensed for HCC treatment and other emerging compounds that are still investigated in preclinical and clinical trials. These molecules are targeting different molecular targets and pathways that are proven to be involved in the pathogenesis of the disease.

Iron commensalism of mesenchymal glioblastoma promotes ferroptosis susceptibility upon dopamine treatment

The heterogeneity of glioblastoma multiforme (GBM) leads to poor patient prognosis. Here, we aim to investigate the mechanism through which GBM heterogeneity is coordinated to promote tumor progression. We find that proneural (PN)-GBM stem cells (GSCs) secreted dopamine (DA) and transferrin (TF), inducing the proliferation of mesenchymal (MES)-GSCs and enhancing their susceptibility toward ferroptosis. PN-GSC-derived TF stimulates MES-GSC proliferation in an iron-dependent manner. DA acts in an autocrine on PN-GSC growth in a DA receptor D1-dependent manner, while in a paracrine it induces TF receptor 1 expression in MES-GSCs to assist iron uptake and thus enhance ferroptotic vulnerability. Analysis of public datasets reveals worse prognosis of patients with heterogeneous GBM with high iron uptake than those with other GBM subtypes. Collectively, the findings here provide evidence of commensalism symbiosis that causes MES-GSCs to become iron-addicted, which in turn provides a rationale for targeting ferroptosis to treat resistant MES GBM.

Glioblastoma stem-cell derived mesenchymal cells become reliant on iron but vulnerable to ferroptosis and within patients of heterogeneous glioblastoma multiforme prognosis for those with high iron uptake is poorer than other subtypes.

Targeting lipophagy as a potential therapeutic strategy for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is becoming an increasingly serious disease worldwide. Unfortunately, no specific drug has been approved to treat NAFLD. Accumulating evidence suggests that lipotoxicity, which is induced by an excess of intracellular triacylglycerols (TAGs), is a potential mechanism underlying the ill-defined progression of NAFLD. Under physiological conditions, a balance is maintained between TAGs and free fatty acids (FFAs) in the liver. TAGs are catabolized to FFAs through neutral lipolysis and/or lipophagy, while FFAs can be anabolized to TAGs through an esterification reaction. However, in the livers of patients with NAFLD, lipophagy appears to fail. Reversing this abnormal state through several lipophagic molecules (mTORC1, AMPK, PLIN, etc.) facilitates NAFLD amelioration; therefore, restoring failed lipophagy may be a highly efficient therapeutic strategy for NAFLD. Here, we outline the lipophagy phases with the relevant important proteins and discuss the roles of lipophagy in the progression of NAFLD. Additionally, the potential candidate drugs with therapeutic value targeting these proteins are discussed to show novel strategies for future treatment of NAFLD.

Synergistic inhibitory effect of berberine and icotinib on non-small cell lung cancer cells via inducing autophagic cell death and apoptosis

Resistance to epidermal growth factor receptor-tyrosin kinase inhibitors (TKIs, e.g. icotinib) remains a major clinical challenge. Non-small cell lung cancer patients with wild-type EGFR and/or K-RAS mutation are primary resistance to EGFR-TKIs. Berberine has been found to have potent anticancer activities via distinct molecular mechanism. In this study, we sought to investigate the therapeutic utility of BBR in combination with icotinib to overcome icotinib resistance in NSCLC cells, and explore the molecular mechanism of synergism of icotinib and BBR to EGFR-resistant NSCLC cells. We used the two EGFR-resistant NSCLC cell lines H460 and H1299 for testing the inhibitory effect of icotinib and/or BBR on them. Moreover, xenograft mouse model was applied for assessing the anti-tumor activities of BBR and icotinib in combination. Results showed that BBR and icotinib have a synergistic inhibitory effect on H460 and H1299 cells through induction of autophagic cell death and apoptosis. Accordingly, the anti-cancer effect of BBR plus icotinib was further confirmed in the NSCLC xenograft mouse models. Combination of BBR and icotinib significantly inhibited the protein expression and the activity of EGFR by inducing autophagic EGFR degradation. BBR plus icotinib resulted in intracellular ROS accumulation, which could mediated autophagy and apoptosis and involved in the suppression of cell migration and invasion. In conclusions, combination application of BBR and icotinib could be an effective strategy to overcome icotinib resistance in the treatment of NSCLC.

GZ17-6.02 and Pemetrexed Interact to Kill Osimertinib-Resistant NSCLC Cells That Express Mutant ERBB1 Proteins

We determined the molecular mechanisms by which the novel therapeutic GZ17-6.02 killed non-small cell lung cancer (NSCLC) cells. Erlotinib, afatinib, and osimertinib interacted with GZ17-6.02 to kill NSCLC cells expressing mutant EGFR proteins. GZ17-6.02 did not interact with any EGFR inhibitor to kill osimertinib-resistant cells. GZ17-6.02 interacted with the thymidylate synthase inhibitor pemetrexed to kill NSCLC cells expressing mutant ERBB1 proteins or mutant RAS proteins or cells that were resistant to EGFR inhibitors. The drugs interacted to activate ATM, the AMPK, and ULK1 and inactivate mTORC1, mTORC2, ERK1/2, AKT, eIF2α; and c-SRC. Knockdown of ATM or AMPKα₁ prevented ULK1 activation. The drugs interacted to cause autophagosome formation followed by flux, which was significantly reduced by knockdown of ATM, AMPKα₁, and eIF2α, or by expression of an activated mTOR protein. Knockdown of Beclin1, ATG5, or [BAX + BAK] partially though significantly reduced drug combination lethality as did expression of activated mTOR/AKT/MEK1 or over-expression of BCL-XL. Expression of dominant negative caspase 9 weakly reduced killing. The drug combination reduced the expression of HDAC2 and HDAC3, which correlated with lower PD-L1, IDO1, and ODC levels and increased MHCA expression. Collectively, our data support consideration of combining GZ17-6.02 and pemetrexed in osimertinib-resistant NSCLC.

Osimertinib-resistant NSCLC cells activate ERBB2 and YAP/TAZ and are killed by neratinib

We performed additional mechanistic analyses to redefine neratinib biology and determined the mechanisms by which the multi-kinase inhibitor neratinib interacted with the thymidylate synthase inhibitor pemetrexed to kill NSCLC cells expressing either mutant KRAS (G12S; Q61H; G12A; G12C) or mutant NRAS (Q61K) or mutant ERBB1 (L858R; L858R T790M; exon 19 deletion). Neratinib rapidly reduced KRASG12V and RAC1G12V nanoclustering which was followed by KRASG12V, but not RAC1G12V, being extensively mislocalized away from the plasma membrane. This correlated with reduced levels of, and reorganized membrane localization of phosphatidylserine and cholesterol. Reduced nanoclustering was not associated with inactivation of ERBB1, Merlin or Ezrin. The drug combination killed cells expressing mutant KRAS, NRAS or mutant ERBB1 proteins. Afatinib or osimertinib resistant cells were killed with a similar efficacy to non-resistant cells. Compared to osimertinib-resistant cells, sensitive cells had less ERBB2 Y1248 phosphorylation. In osimertinib resistant H1975 cells, the drug combination was less capable of inactivating AKT, mTOR, STAT3, STAT5, ERK1/2 whereas it gained the ability to inactivate ERBB3. In resistant H1650 cells, the drug combination was less capable of inactivating JAK2 and STAT5. Sensitive cells exhibited elevated basal phosphorylation of YAP and TAZ. In resistant cells, portions of YAP and TAZ were localized in the nucleus. [Neratinib + pemetrexed] increased phosphorylation of YAP and TAZ, caused their nuclear exit, and enhanced ERBB2 degradation. Thus, neratinib targets an unidentified protein whose functional inhibition directly results in RAS inactivation and tumor cell killing. Our data prove that, albeit indirectly, oncogenic RAS proteins are druggable by neratinib.

Sorafenib prevents the proliferation and induces the apoptosis of liver cancer cells by regulating autophagy and hypoxia-inducible factor-1

Sorafenib has been approved as a systemic drug for advanced liver cancer; however, the underlying mechanisms remain unclear. The present study aimed to investigate the effects of sorafenib on the proliferation, autophagy and apoptosis of HepG2 cells under hypoxia. Briefly, reverse transcription-quantitative PCR and western blotting was performed to quantify HIF-1, LC3II/I, mTOR and p70s6K expression levels. Cell proliferation was determined using the Cell Counting Kit-8 assay and the cell apoptosis rate was evaluated using flow cytometry. The results demonstrated that autophagy and apoptosis were induced by hypoxia, and that sorafenib further enhanced hypoxia-induced autophagy and apoptosis in HepG2 cells in a dose-dependent manner. Furthermore, the mechanism of sorafenib-mediated autophagy in liver cancer cell were investigated by using chloroquine (CQ). The results showed that CQ significantly inhibited autophagy by decreasing LC3II/LC3I ratio in HepG2 cells treated with sorafenib and/or hypoxia. By contrast, sorafenib could increase the expression of hypoxia-inducible factor-1 (HIF-1) and of the autophagy marker (LC3II/I) and decrease the expression of mammalian target of rapamycin and p70 ribosomal S6 kinase in HepG2 cells under normoxia and hypoxia conditions, suggesting that sorafenib could induce hypoxia and autophagy in liver cancer cells. In addition, sorafenib was demonstrated to prevent proliferation and induce apoptosis of HepG2 cells under normoxia and hypoxia. Sorafenib could also prevent the malignant behavior of HepG2 by inducing hypoxia and autophagy. In summary, the findings from the present study suggested that sorafenib may inhibit liver cancer progression by activating autophagy and HIF-1 signaling pathway.

Autophagy in liver diseases

Autophagy is the liver cell energy recycling system regulating a variety of homeostatic mechanisms. Damaged organelles, lipids and proteins are degraded in the lysosomes and their elements are re-used by the cell. Investigations on autophagy have led to the award of two Nobel Prizes and a health of important reports. In this review we describe the fundamental functions of autophagy in the liver including new data on the regulation of autophagy. Moreover we emphasize the fact that autophagy acts like a two edge sword in many occasions with the most prominent paradigm being its involvement in the initiation and progress of hepatocellular carcinoma. We also focused to the implication of autophagy and its specialized forms of lipophagy and mitophagy in the pathogenesis of various liver diseases. We analyzed autophagy not only in well studied diseases, like alcoholic and nonalcoholic fatty liver and liver fibrosis but also in viral hepatitis, biliary diseases, autoimmune hepatitis and rare diseases including inherited metabolic diseases and also acetaminophene hepatotoxicity. We also stressed the different consequences that activation or impairment of autophagy may have in hepatocytes as opposed to Kupffer cells, sinusoidal endothelial cells or hepatic stellate cells. Finally, we analyzed the limited clinical data compared to the extensive experimental evidence and the possible future therapeutic interventions based on autophagy manipulation.

The role of cell signaling in the crosstalk between autophagy and apoptosis in the regulation of tumor cell survival in response to sorafenib and neratinib

The molecular mechanisms by which tumor cells survive or die following therapeutic interventions are complex. There are three broadly defined categories of cell death processes: apoptosis (Type I), autophagic cell death (Type II), and necrosis (Type III). In hematopoietic tumor cells, the majority of toxic stimuli cause these cells to undergo a death process called apoptosis; apoptosis specifically involves the cleavage of DNA into large defined pieces and their subsequent localization in vesicles. Thus, 'pure' apoptosis largely lacks inflammatory potential. In carcinomas, however, the mechanisms by which tumor cells ultimately die are considerably more complex. Although the machinery of apoptosis is engaged by toxic stimuli, other processes such as autophagy ("self-eating") and replicative cell death can lead to observations that do not simplistically correspond to any of the individual Type I-III formalized death categories. The 'hybrid' forms of cell death observed in carcinoma cells result in cellular materials being released into the extracellular space without packaging, which promotes inflammation, potentially leading to the accelerated re-growth of surviving tumor cells by macrophages. Drugs as single agents or in combinations can simultaneously initiate signaling via both apoptotic and autophagic pathways. Based on the tumor type and its oncogene drivers, as well as the drug(s) being used and the duration and intensity of the autophagosome signal, apoptosis and autophagy have the potential to act in concert to kill or alternatively that the actions of either pathway can act to suppress signaling by the other pathway. And, there also is evidence that autophagic flux, by causing lysosomal protease activation, with their subsequent release into the cytosol, can directly mediate killing. This review will discuss the interactive biology between apoptosis and autophagy in carcinoma cells. Finally, the molecular actions of the FDA-approved drugs neratinib and sorafenib, and how they enhance both apoptotic and toxic autophagic processes, alone or in combination with other agents, is discussed in a bench-to-bedside manner.

The novel proautophagy anticancer drug ABTL0812 potentiates chemotherapy in adenocarcinoma and squamous nonsmall cell lung cancer

Around 40% of newly diagnosed lung cancer patients are Stage IV, where the improvement of survival and reduction of disease-related adverse events is the main goal for oncologists. In this scenario, we present preclinical evidence supporting the use of ABTL0812 in combination with chemotherapy for treating advanced and metastatic Nonsmall cell lung adenocarcinomas (NSCLC) and squamous carcinomas. ABTL0812 is a new chemical entity, currently in Phase 1b/2a clinical trial for advanced squamous NSCLC in combination with paclitaxel and carboplatin (P/C), after successfully completing the first-in-human trial where it showed an excellent safety profile and signs of efficacy. We show here that ABTL0812 inhibits Akt/mTOR axis by inducing the overexpression of TRIB3 and activating autophagy in lung squamous carcinoma cell lines. Furthermore, treatment with ABTL0812 also induces AMPK activation and ROS accumulation. Moreover, combination of ABTL0812 with chemotherapy markedly increases the therapeutic effect of chemotherapy without increasing toxicity. We further show that combination of ABTL0812 and chemotherapy induces nonapoptotic cell death mediated by TRIB3 activation and autophagy induction. We also present preliminary clinical data indicating that TRIB3 could serve as a potential novel pharmacodynamic biomarker to monitor ABTL0812 activity administered alone or in combination with chemotherapy in squamous NSCLC patients. The safety profile of ABTL0812 and its good synergy with chemotherapy potentiate the therapeutic potential of current lines of treatment based on chemotherapy regimens, arising as a promising option for improving these patients therapeutic expectancy.

Signaling alterations caused by drugs and autophagy

Autophagy is an evolutionary conserved process that recycles cellular materials in times of nutrient restriction to maintain viability. In cancer therapeutics, the role of autophagy in response to multi-kinase inhibitors, alone or when combined with histone deacetylase (HDAC) inhibitors acts, generally, to facilitate the killing of tumor cells. Furthermore, the formation of autophagosomes and subsequent degradation of their contents can reduce the expression of HDAC proteins themselves as well as of other signaling regulatory molecules such as protein chaperones and mutated RAS proteins. Reduced levels of HDAC6 causes the acetylation and inactivation of heat shock protein 90, and, together with reduced expression of the chaperones HSP70 and GRP78, generates a strong endoplasmic reticulum (ER) stress response. Prolonged intense ER stress signaling causes tumor cell death. Reduced expression of HDACs 1, 2 and 3 causes the levels of programed death ligand 1 (PD-L1) to decline and the expression of Class I MHCA to increase which correlates with elevated immunogenicity of the tumor cells in vivo. This review will specifically focus on the downstream implications that result from autophagic-degradation of HDACs, RAS and protein chaperones.

Discovery of N-phenyl-(2,4-dihydroxypyrimidine-5-sulfonamido) phenylurea-based thymidylate synthase (TS) inhibitor as a novel multi-effects antitumor drugs with minimal toxicity

Thymidylate synthase (TS) is a hot target for tumor chemotherapy, and its inhibitors are an essential direction for anti-tumor drug research. To our knowledge, currently, there are no reported thymidylate synthase inhibitors that could inhibit cancer cell migration. Therefore, for optimal therapeutic purposes, combines our previous reports and findings, we hope to obtain a multi-effects inhibitor. This study according to the principle of flattening we designed and synthesized 18 of N-phenyl-(2,4-dihydroxypyrimidine-5-sulfonamido)phenyl urea derivatives as multi-effects inhibitors. The biological evaluation results showed that target compounds could significantly inhibit the hTS enzyme, BRaf kinase and EGFR kinase activity in vitro, and most of the compounds had excellent anti-cell viability for six cancer cell lines. Notably, the candidate compound L14e (IC₅₀ = 0.67 μM) had the superior anti-cell viability and safety to A549 and H460 cells compared with pemetrexed. Further studies had shown that L14e could cause G1/S phase arrest then induce intrinsic apoptosis. Transwell, western blot, and tube formation results proved that L14e could inhibit the activation of the EGFR signaling pathway, then ultimately achieve the purpose of inhibiting cancer cell migration and angiogenesis in cancer tissues. Furthermore, in vivo pharmacology evaluations of L14e showed significant antitumor activity in A549 cells xenografts with minimal toxicity. All of these results demonstrated that the L14e has the potential for drug discovery as a multi-effects inhibitor and provides a new reference for clinical treatment of non-small cell lung cancer.

A Phase I Study of Pegylated Arginine Deiminase (Pegargiminase), Cisplatin, and Pemetrexed in Argininosuccinate Synthetase 1-Deficient Recurrent High-grade Glioma

PURPOSE

Patients with recurrent high-grade gliomas (HGG) are usually managed with alkylating chemotherapy ± bevacizumab. However, prognosis remains very poor. Preclinically, we showed that HGGs are a target for arginine depletion with pegargiminase (ADI-PEG20) due to epimutations of argininosuccinate synthetase (ASS1) and/or argininosuccinate lyase (ASL). Moreover, ADI-PEG20 disrupts pyrimidine pools in ASS1-deficient HGGs, thereby impacting sensitivity to the antifolate, pemetrexed.

PATIENTS AND METHODS

We expanded a phase I trial of ADI-PEG20 with pemetrexed and cisplatin (ADIPEMCIS) to patients with ASS1-deficient recurrent HGGs (NCT02029690). Patients were enrolled (01/16-06/17) to receive weekly ADI-PEG20 36 mg/m² intramuscularly plus pemetrexed 500 mg/m² and cisplatin 75 mg/m² intravenously once every 3 weeks for up to 6 cycles. Patients with disease control were allowed ADI-PEG20 maintenance. The primary endpoints were safety, tolerability, and preliminary estimates of efficacy.

RESULTS

Ten ASS1-deficient heavily pretreated patients were treated with ADIPEMCIS therapy. Treatment was well tolerated with the majority of adverse events being Common Terminology Criteria for Adverse Events v4.03 grade 1-2. The best overall response was stable disease in 8 patients (80%). Plasma arginine was suppressed significantly below baseline with a reciprocal increase in citrulline during the sampling period. The anti-ADI-PEG20 antibody titer rose during the first 4 weeks of treatment before reaching a plateau. Median progression-free survival (PFS) was 5.2 months (95% confidence interval (CI), 2.5-20.8) and overall survival was 6.3 months (95% CI, 1.8-9.7).

CONCLUSIONS

In this recurrent HGG study, ADIPEMCIS was well tolerated and compares favorably to historical controls. Additional trials of ADI-PEG20 in HGG are planned.

Diverse Functions of Autophagy in Liver Physiology and Liver Diseases

Autophagy is a catabolic process by which eukaryotic cells eliminate cytosolic materials through vacuole-mediated sequestration and subsequent delivery to lysosomes for degradation, thus maintaining cellular homeostasis and the integrity of organelles. Autophagy has emerged as playing a critical role in the regulation of liver physiology and the balancing of liver metabolism. Conversely, numerous recent studies have indicated that autophagy may disease-dependently participate in the pathogenesis of liver diseases, such as liver hepatitis, steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma. This review summarizes the current knowledge on the functions of autophagy in hepatic metabolism and the contribution of autophagy to the pathophysiology of liver-related diseases. Moreover, the impacts of autophagy modulation on the amelioration of the development and progression of liver diseases are also discussed.

Palbociclib augments Neratinib killing of tumor cells that is further enhanced by HDAC inhibition

Cancers expressing mutant RAS are associated with a weaker response to chemotherapy and a shorter overall patient survival. We have demonstrated that the irreversible inhibitor of ERBB1/2/4, neratinib, inhibits ERBB1/2/4 and causes their internalization and autolysosomal degradation. Fellow-traveler membrane proteins with RTKs, including mutant K-/N-RAS, were also degraded. We discovered that the CDK4/6 inhibitor palbociclib increased autophagosome and then autolysosome levels in a time dependent fashion, did not reduce mTOR activity, and interacted with temsirolimus to kill. Neratinib and palbociclib interacted in a greater than additive manner to increase autophagosome and then autolysosome levels in a time dependent fashion, and to cause tumor cell killing. Killing required the expression of ATM and AMPKα, Beclin1 and ATG5, BAX and BAK and of AIF, but not of caspase 9. In some cells over-expression of BCL-XL was protective whereas in others it was ineffective. The lethality of [neratinib + palbociclib] was modestly enhanced by the PDE5 inhibitor sildenafil and strongly enhanced by the HDAC inhibitor sodium valproate. This was associated with K-RAS degradation and a greater than additive increase in autophagosome and autolysosome levels. Killing by the three-drug combination required ATM and AMPKα, and, to a greater extent, Beclin1 and ATG5. In vivo, [valproate + palbociclib] and [neratinib + valproate + palbociclib] interacted to suppress the growth of a carboplatin/paclitaxel resistant PDX ovarian tumors that express a mutant N-RAS. Our data support performing a future three-drug trial with these agents.

PDE5 inhibitors enhance the lethality of pemetrexed through inhibition of multiple chaperone proteins and via the actions of cyclic GMP and nitric oxide

Phosphodiesterase 5 (PDE5) inhibitors prevent the breakdown of cGMP that results in prolonged protein kinase G activation and the generation of nitric oxide. PDE5 inhibitors enhanced the anti-NSCLC cell effects of the NSCLC therapeutic pemetrexed. [Pemetrexed + sildenafil] activated an eIF2α – ATF4 – CHOP – Beclin1 pathway causing formation of toxic autophagosomes; activated a protective IRE1 – XBP-1 – chaperone induction pathway; and activated a toxic eIF2α – CHOP – DR4 / DR5 / CD95 induction pathway. [Pemetrexed + sildenafil] reduced the expression of c-FLIP-s, MCL-1 and BCL-XL that was blocked in a cell-type -dependent fashion by either over-expression of HSP90 / GRP78 / HSP70 / HSP27 or by blockade of eIF2α-CHOP signaling. Knock down of PKGI/II abolished the ability of sildenafil to enhance pemetrexed toxicity whereas pan-inhibition of NOS using L-NAME or knock down of [iNOS + eNOS] only partially reduced the lethal drug interaction. Pemetrexed reduced the ATPase activities of HSP90 and HSP70 in an ATM-AMPK-dependent fashion that was enhanced by sildenafil signaling via PKGI/II. The drug combination activated an ATM-AMPK-TSC2 pathway that was associated with reduced mTOR S2448 and ULK-1 S757 phosphorylation and increased ULK-1 S317 and ATG13 S318 phosphorylation. These effects were prevented by chaperone over-expression or by expression of an activated form of mTOR that prevented autophagosome formation and reduced cell killing. In two models of NSCLC, sildenafil enhanced the ability of pemetrexed to suppress tumor growth. Collectively we argue that the combination of [pemetrexed + PDE5 inhibitor] should be explored in a new NSCLC phase I trial.

The Complex Link between Apoptosis and Autophagy: a Promising New Role for RB

Physiological processes, as autophagy, proliferation and apoptosis are affected during carcinogenesis. Restoring cellular sensitivity to apoptotic stimuli, such as the antineoplastic cocktails, has been explored as a strategy to eliminate cancer cells. Autophagy, a physiological process of recycling organelles and macromolecules can be deviated from homeostasis to support cancer cells survival, proliferation, escape from apoptosis, and therapy resistance. The relationship between autophagy and apoptosis is complex and many stimuli can induce both processes. Most chemotherapeutic agents induce autophagy and it is not clear whether and how this chemotherapy-induced autophagy might contribute to resistance to apoptosis. Here, we review current strategies to sensitize cancer cells by interfering with autophagy. Moreover, we discuss a new link between autophagy and apoptosis: the tumor suppressor retinoblastoma protein (RB). Inactivation of RB is one of the earliest and more frequent hallmarks of cancer transformation, known to control cell cycle progression and apoptosis. Therefore, understanding RB functions in controlling cell fate is essential for an effective translation of RB status in cancer samples to the clinical outcome.

Autophagy Modulation in Cancer: Current Knowledge on Action and Therapy

In the last two decades, accumulating evidence pointed to the importance of autophagy in various human diseases. As an essential evolutionary catabolic process of cytoplasmatic component digestion, it is generally believed that modulating autophagic activity, through targeting specific regulatory actors in the core autophagy machinery, may impact disease processes. Both autophagy upregulation and downregulation have been found in cancers, suggesting its dual oncogenic and tumor suppressor properties during malignant transformation. Identification of the key autophagy targets is essential for the development of new therapeutic agents. Despite this great potential, no therapies are currently available that specifically focus on autophagy modulation. Although drugs like rapamycin, chloroquine, hydroxychloroquine, and others act as autophagy modulators, they were not originally developed for this purpose. Thus, autophagy may represent a new and promising pharmacologic target for future drug development and therapeutic applications in human diseases. Here, we summarize our current knowledge in regard to the interplay between autophagy and malignancy in the most significant tumor types: pancreatic, breast, hepatocellular, colorectal, and lung cancer, which have been studied in respect to autophagy manipulation as a promising therapeutic strategy. Finally, we present an overview of the most recent advances in therapeutic strategies involving autophagy modulators in cancer.

Phase I study of pemetrexed with sorafenib in advanced solid tumors

Purpose

To determine if combination treatment with pemetrexed and sorafenib is safe and tolerable in patients with advanced solid tumors.

Results

Thirty-seven patients were enrolled and 36 patients were treated (24 in cohort A; 12 in cohort B). The cohort A dose schedule resulted in problematic cumulative toxicity, while the cohort B dose schedule was found to be more tolerable. The maximum tolerated dose (MTD) was pemetrexed 750 mg/m² every 14 days with oral sorafenib 400 mg given twice daily on days 1–5. Because dosing delays and modifications were associated with the MTD, the recommended phase II dose was declared to be pemetrexed 500 mg/m² every 14 days with oral sorafenib 400 mg given twice daily on days 1–5. Thirty-three patients were evaluated for antitumor activity. One complete response and 4 partial responses were observed (15% overall response rate). Stable disease was seen in 15 patients (45%). Four patients had a continued response at 6 months, including 2 of 5 patients with triple-negative breast cancer.

Experimental Design

A phase I trial employing a standard 3 + 3 design was conducted in patients with advanced solid tumors. Cohort A involved a novel dose escalation schema exploring doses of pemetrexed every 14 days with continuous sorafenib. Cohort B involved a modified schedule of sorafenib dosing on days 1–5 of each 14-day pemetrexed cycle. Radiographic assessments were conducted every 8 weeks.

Conclusions

Pemetrexed and intermittent sorafenib therapy is a safe and tolerable combination for patients, with promising activity seen in patients with breast cancer.

Gene and MicroRNA Perturbations of Cellular Response to Pemetrexed Implicate Biological Networks and Enable Imputation of Response in Lung Adenocarcinoma

Pemetrexed is indicated for non-small cell lung carcinoma and mesothelioma, but often has limited efficacy due to drug resistance. To probe the molecular mechanisms underlying chemotherapeutic response, we performed mRNA and microRNA (miRNA) expression profiling of pemetrexed treated and untreated lymphoblastoid cell lines (LCLs) and applied a hierarchical Bayesian method. We identified genetic variation associated with gene expression in human lung tissue for the most significant differentially expressed genes (Benjamini-Hochberg [BH] adjusted p < 0.05) using the Genotype-Tissue Expression data and found evidence for their clinical relevance using integrated molecular profiling and lung adenocarcinoma survival data from The Cancer Genome Atlas project. We identified 39 miRNAs with significant differential expression (BH adjusted p < 0.05) in LCLs. We developed a gene expression based imputation model of drug sensitivity, quantified its prediction performance, and found a significant correlation of the imputed phenotype generated from expression data with survival time in lung adenocarcinoma patients. Differentially expressed genes (MTHFD2 and SUFU) that are putative targets of differentially expressed miRNAs also showed differential perturbation in A549 fusion lung tumor cells with further replication in A549 cells. Our study suggests pemetrexed may be used in combination with agents that target miRNAs to increase its cytotoxicity.

The afatinib resistance of in vivo generated H1975 lung cancer cell clones is mediated by SRC/ERBB3/c-KIT/c-MET compensatory survival signaling

We generated afatinib resistant clones of H1975 lung cancer cells by transient exposure of established tumors to the drug and collected the re-grown tumors. Afatinib resistant H1975 clones did not exhibit any additional mutations in proto-oncogenes when compared to control clones. Afatinib resistant H1975 tumor clones expressed less PTEN than control clones and in afatinib resistant clones this correlated with increased basal SRC Y416, ERBB3 Y1289, AKT T308 and mTOR S2448 phosphorylation, decreased expression of ERBB1, ERBB2 and ERBB3 and increased total expression of c-MET, c-KIT and PDGFRβ. Afatinib resistant clones were selectively killed by knock down of [ERBB3 + c-MET + c-KIT] but not by the individual or doublet knock down combinations. The combination of the ERBB1/2/4 inhibitor afatinib with the SRC family inhibitor dasatinib killed afatinib resistant H1975 cells in a greater than additive fashion; other drugs used in combination with dasatinib such as sunitinib, crizotinib and amufatinib were less effective. [Afatinib + dasatinib] treatment profoundly inactivated ERBB3, AKT and mTOR in the H1975 afatinib resistant clones and increased ATG13 S318 phosphorylation. Knock down of ATG13, Beclin1 or eIF2α strong suppressed killing by [ERBB3 + c-MET + c-KIT] knock down, but were only modestly protective against [afatinib + dasatinib] lethality. Thus afatinib resistant H1975 NSCLC cells rely on ERBB1- and SRC-dependent hyper-activation of residual ERBB3 and elevated signaling, due to elevated protein expression, from wild type c-MET and c-KIT to remain alive. Inhibition of ERBB3 signaling via both blockade of SRC and ERBB1 results in tumor cell death.

PDE5 inhibitors enhance the lethality of [pemetrexed + sorafenib]

The combination of pemetrexed and sorafenib has significant clinical activity against a wide variety of tumor types in patients and the present studies were performed to determine whether sildenafil enhances the killing potential of [pemetrexed + sorafenib]. In multiple genetically diverse lung cancer cell lines, sildenafil enhanced the lethality of [pemetrexed + sorafenib]. The three-drug combination reduced the activities of AKT, mTOR and STAT transcription factors; increased the activities of eIF2α and ULK-1; lowered the expression of MCL-1, BCL-XL, thioredoxin and SOD2; and increased the expression of Beclin1. Enhanced cell killing by sildenafil was blocked by inhibition of death receptor signaling and autophagosome formation. Enforced activation of STAT3 and AKT or inhibition of JNK significantly reduced cell killing. The enhanced cell killing caused by sildenafil was more reliant on increased PKG signaling than on the generation of nitric oxide. In vivo sildenafil enhanced the anti-tumor properties of [pemetrexed + sorafenib]. Based on our data we argue that additional clinical studies combining pemetrexed, sorafenib and sildenafil are warranted.

Targeting Neovasculature with Multitargeted Antiangiogenesis Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer

Chemotherapy has reached a plateau in the efforts for survival improvement in non-small cell lung cancer (NSCLC). The growing knowledge of NSCLC molecular pathobiology has led to the development of new treatments that target specific tumor functions. Angiogenesis is a tumor function leading to the formation of new tumor vessels that are crucial for its survival. Although vascular endothelial growth factor (VEGF) plays a primary role in angiogenesis, the inhibition of the VEGF pathway with VEGF-receptor (VEGFR) tyrosine kinase inhibitors (TKIs) is associated with a modest survival benefit due to the development of resistance by the tumor that has been mainly attributed to the up-regulation of other stimulators of angiogenesis. Thus, the use of multitargeted antiangiogenesis TKIs (MATKIs) for simultaneous inhibition of multiple angiogenic pathways has been proposed. This review summarizes data about novel treatment strategies incorporating the inhibition of angiogenesis with MATKIs in NSCLC. The data from all relevant studies shows that MATKIs do not offer additional survival benefit to currently available chemotherapeutic options in unselected NSCLC patients. However, the diversity in disease response to MATKI-containing regimens implies that specific patient subgroups may benefit from or be harmed by these agents. In this context, most studies agree that the VEGFR-targeting MATKIs are harmful in squamous NSCLC while specific MATKIs (i.e., motesanib, vandetanib and nintedanib) are associated with improved progression free survival in non-squamous NSCLC. However, overall survival benefit was found only in adenocarcinoma and Asian non-squamous NSCLC patients with the use of nintedanib and motesanib, respectively.

Autophagy orchestrates adaptive responses to targeted therapy in endometrial cancer

Targeted therapies in endometrial cancer (EC) using kinase inhibitors rarely result in complete tumor remission and are frequently challenged by the appearance of refractory cell clones, eventually resulting in disease relapse. Dissecting adaptive mechanisms is of vital importance to circumvent clinical drug resistance and improve the efficacy of targeted agents in EC. Sorafenib is an FDA-approved multitarget tyrosine and serine/threonine kinase inhibitor currently used to treat hepatocellular carcinoma, advanced renal carcinoma and radioactive iodine-resistant thyroid carcinoma. Unfortunately, sorafenib showed very modest effects in a multi-institutional phase II trial in advanced uterine carcinoma patients. Here, by leveraging RNA-sequencing data from the Cancer Cell Line Encyclopedia and cell survival studies from compound-based high-throughput screenings we have identified the lysosomal pathway as a potential compartment involved in the resistance to sorafenib. By performing additional functional biology studies we have demonstrated that this resistance could be related to macroautophagy/autophagy. Specifically, our results indicate that sorafenib triggers a mechanistic MAPK/JNK-dependent early protective autophagic response in EC cells, providing an adaptive response to therapeutic stress. By generating in vivo subcutaneous EC cell line tumors, lung metastatic assays and primary EC orthoxenografts experiments, we demonstrate that targeting autophagy enhances sorafenib cytotoxicity and suppresses tumor growth and pulmonary metastasis progression. In conclusion, sorafenib induces the activation of a protective autophagic response in EC cells. These results provide insights into the unopposed resistance of advanced EC to sorafenib and highlight a new strategy for therapeutic intervention in recurrent EC.

Inhibition of autophagy potentiates pemetrexed and simvastatin-induced apoptotic cell death in malignant mesothelioma and non-small cell lung cancer cells

Pemetrexed, a multitarget antifolate used to treat malignant mesothelioma and non-small cell lung cancer (NSCLC), has been shown to stimulate autophagy. In this study, we determined whether autophagy could be induced by pemetrexed and simvastatin cotreatment in malignant mesothelioma and NSCLC cells. Furthermore, we determined whether inhibition of autophagy drives apoptosis in malignant mesothelioma and NSCLC cells. Malignant mesothelioma MSTO-211H and A549 NSCLC cells were treated with pemetrexed and simvastatin alone and in combination to evaluate their effect on autophagy and apoptosis. Cotreatment with pemetrexed and simvastatin induced greater caspase-dependent apoptosis and autophagy than either drug alone in malignant mesothelioma and NSCLC cells. 3-Methyladenine (3-MA), ATG5 siRNA, bafilomycin A, and E64D/pepstatin A enhanced the apoptotic potential of pemetrexed and simvastatin, whereas rapamycin and LY294002 attenuated their induction of caspase-dependent apoptosis. Our data indicate that pemetrexed and simvastatin cotreatment augmented apoptosis and autophagy in malignant mesothelioma and NSCLC cells. Inhibition of pemetrexed and simvastatin-induced autophagy was shown to enhance apoptosis, suggesting that this could be a novel therapeutic strategy against malignant mesothelioma and NSCLC.

Rationally Repurposing Ruxolitinib (Jakafi (®)) as a Solid Tumor Therapeutic

We determined whether the approved myelofibrosis drug ruxolitinib (Jakafi^®), an inhibitor of Janus kinases 1/2 (JAK1 and JAK2), could be repurposed as an anti-cancer agent for solid tumors. Ruxolitinib synergistically interacted with dual ERBB1/2/4 inhibitors to kill breast as well as lung, ovarian and brain cancer cells. Knock down of JAK1/2 or of ERBB1/2/3/4 recapitulated on-target drug effects. The combination of (ruxolitinib + ERBB1/2/4 inhibitor) rapidly inactivated AKT, mTORC1, mTORC2, STAT3, and STAT5, and activated eIF2α. In parallel, the drug combination reduced expression of MCL-1, BCL-XL, HSP90, HSP70, and GRP78, and increased expression of Beclin1. Activated forms of STAT3, AKT, or mTOR prevented the drug-induced decline in BCL-XL, MCL-1, HSP90, and HSP70 levels. Over-expression of chaperones maintained AKT/mTOR activity in the presence of drugs and protected tumor cells from the drug combination. Expression of dominant negative eIF2α S51A prevented the increase in Beclin1 expression and protected tumor cells from the drug combination. Loss of mTOR activity was associated with increased ATG13 S318 phosphorylation and with autophagosome formation. Autophagosomes initially co-localized with mitochondria and subsequently with lysosomes. Knock down of Beclin1 suppressed: drug-induced mitophagy; the activation of the toxic BH3 domain proteins BAX and BAK; and tumor cell killing. Knock down of apoptosis-inducing factor (AIF) protected tumor cells from the drug combination, whereas blockade of caspase 9 signaling did not. The drug combination released AIF into the cytosol and increased nuclear AIF: eIF3A co-localization. A 4-day transient exposure of orthotopic tumors to (ruxolitinib + afatinib) profoundly reduced mammary tumor growth over the following 35 days. Re-grown tumors exhibited high levels of BAD S112 phosphorylation and activation of ERK1/2 and NFκB. Our data demonstrate that mitophagy is an essential component of (ruxolitinib + ERBB inhibitor) lethality and that this drug combination should be explored in a phase I trial in solid tumor patients.

Modulation of Autophagy by Sorafenib: Effects on Treatment Response

The multikinase inhibitor sorafenib is, at present, the only drug approved for the treatment of hepatocellular carcinoma (HCC), one of the most lethal types of cancer worldwide. However, the increase in the number of sorafenib tumor resistant cells reduces efficiency. A better knowledge of the intracellular mechanism of the drug leading to reduced cell survival could help to improve the benefits of sorafenib therapy. Autophagy is a bulk cellular degradation process activated in a broad range of stress situations, which allows cells to degrade misfolded proteins or dysfunctional organelles. This cellular route can induce survival or death, depending on cell status and media signals. Sorafenib, alone or in combination with other drugs is able to induce autophagy, but cell response to the drug depends on the complex integrative crosstalk of different intracellular signals. In cancerous cells, autophagy can be regulated by different cellular pathways (Akt-related mammalian target of rapamycin (mTOR) inhibition, 5′ AMP-activated protein kinase (AMPK) induction, dissociation of B-cell lymphoma 2 (Bcl-2) family proteins from Beclin-1), or effects of some miRNAs. Inhibition of mTOR signaling by sorafenib and diminished interaction between Beclin-1 and myeloid cell leukemia 1 (Mcl-1) have been related to induction of autophagy in HCC. Furthermore, changes in some miRNAs, such as miR-30α, are able to modulate autophagy and modify sensitivity in sorafenib-resistant cells. However, although AMPK phosphorylation by sorafenib seems to play a role in the antiproliferative action of the drug, it does not relate with modulation of autophagy. In this review, we present an updated overview of the effects of sorafenib on autophagy and its related activation pathways, analyzing in detail the involvement of autophagy on sorafenib sensitivity and resistance.

[Pemetrexed + Sorafenib] lethality is increased by inhibition of ERBB1/2/3-PI3K-NFκB compensatory survival signaling

In the completed phase I trial NCT01450384 combining the anti-folate pemetrexed and the multi-kinase inhibitor sorafenib it was observed that 20 of 33 patients had prolonged stable disease or tumor regression, with one complete response and multiple partial responses. The pre-clinical studies in this manuscript were designed to determine whether [pemetrexed + sorafenib] -induced cell killing could be rationally enhanced by additional signaling modulators. Multiplex assays performed on tumor material that survived and re-grew after [pemetrexed + sorafenib] exposure showed increased phosphorylation of ERBB1 and of NFκB and IκB; with reduced IκB and elevated G-CSF and KC protein levels. Inhibition of JAK1/2 downstream of the G-CSF/KC receptors did not enhance [pemetrexed + sorafenib] lethality whereas inhibition of ERBB1/2/4 using kinase inhibitory agents or siRNA knock down of ERBB1/2/3 strongly promoted killing. Inhibition of ERBB1/2/4 blocked [pemetrexed + sorafenib] stimulated NFκB activation and SOD2 expression; and expression of IκB S32A S36A significantly enhanced [pemetrexed + sorafenib] lethality. Sorafenib inhibited HSP90 and HSP70 chaperone ATPase activities and reduced the interactions of chaperones with clients including c-MYC, CDC37 and MCL-1. In vivo, a 5 day transient exposure of established mammary tumors to lapatinib or vandetanib significantly enhanced the anti-tumor effect of [pemetrexed + sorafenib], without any apparent normal tissue toxicities. Identical data to that in breast cancer were obtained in NSCLC tumors using the ERBB1/2/4 inhibitor afatinib. Our data argue that the combination of pemetrexed, sorafenib and an ERBB1/2/4 inhibitor should be explored in a new phase I trial in solid tumor patients.

Ruxolitinib synergizes with DMF to kill via BIM+BAD-induced mitochondrial dysfunction and via reduced SOD2/TRX expression and ROS

We determined whether the myelofibrosis drug ruxolitinib, an inhibitor of Janus kinases 1/2 (JAK1 and JAK2), could interact with the multiple sclerosis drug dimethyl-fumarate (DMF) to kill tumor cells; studies used the in vivo active form of the drug, mono-methyl fumarate (MMF). Ruxolitinib interacted with MMF to kill brain, breast, lung and ovarian cancer cells, and enhanced the lethality of standard of care therapies such as paclitaxel and temozolomide. MMF also interacted with other FDA approved drugs to kill tumor cells including Celebrex® and Gilenya®. The combination of [ruxolitinib + MMF] inactivated ERK1/2, AKT, STAT3 and STAT5; reduced expression of MCL-1, BCL-XL, SOD2 and TRX; increased BIM expression; decreased BAD S112 S136 phosphorylation; and enhanced pro-caspase 3 cleavage. Expression of activated forms of STAT3, MEK1 or AKT each significantly reduced drug combination lethality; prevented BAD S112 S136 dephosphorylation and decreased BIM expression; and preserved TRX, SOD2, MCL-1 and BCL-XL expression. The drug combination increased the levels of reactive oxygen species in cells, and over-expression of TRX or SOD2 prevented drug combination tumor cell killing. Over-expression of BCL-XL or knock down of BAX, BIM, BAD or apoptosis inducing factor (AIF) protected tumor cells. The drug combination increased AIF : HSP70 co-localization in the cytosol but this event did not prevent AIF : eIF3A association in the nucleus.

Differential regulation of autophagy and cell viability by ceramide species

The present studies sought to determine whether the anti-folate pemetrexed (Alimta) and the sphingosine-1-phosphate receptor modulator FTY720 (Fingolimod, Gilenya) interacted to kill tumor cells. FTY720 and pemetrexed interacted in a greater than additive fashion to kill breast, brain and colorectal cancer cells. Loss of p53 function weakly enhanced the toxicity of FTY720 whereas deletion of activated RAS strongly or expression of catalytically inactive AKT facilitated killing. Combined drug exposure reduced the activity of AKT, p70 S6K and mTOR and activated JNK and p38 MAPK. Expression of activated forms of AKT, p70 S6K and mTOR or inhibition of JNK and p38 MAPK suppressed the interaction between FTY720 and pemetrexed. Treatment of cells with FTY720 and pemetrexed increased the numbers of early autophagosomes but not autolysosomes, which correlated with increased LC3II processing and increased p62 levels, suggestive of stalled autophagic flux. Knock down of ATG5 or Beclin1 suppressed autophagosome formation and cell killing. Knock down of ceramide synthase 6 suppressed autophagosome production and cell killing whereas knock down of ceramide synthase 2 enhanced vesicle formation and facilitated death. Collectively our findings argue that pemetrexed and FTY720 could be a novel adjunct modality for breast cancer treatment.

Autophagy in hepatocellular carcinomas: from pathophysiology to therapeutic response

Autophagy is an intracellular lysosomal degradation process performed by the cells to maintain energy balance. The autophagy response plays an important role in the progression of liver disease due to hepatitis virus infection, alcoholic liver disease, nonalcoholic fatty liver disease, liver cirrhosis, and hepatocellular carcinoma (HCC). An increased autophagy response also contributes to the pathogenesis of liver disease through modulation of innate and adaptive immune responses; a defective cellular autophagy response leads to the development of HCC. Recent progress in the field indicates that autophagy modulation provides a novel targeted therapy for human liver cancer. The purpose of this review is to update our understanding of how the cellular autophagy response impacts the pathophysiology of liver disease and HCC treatment.

Ceramide Synthase 6 Is a Novel Target of Methotrexate Mediating Its Antiproliferative Effect in a p53-Dependent Manner

We previously reported that ceramide synthase 6 (CerS6) is elevated in response to folate stress in cancer cells, leading to enhanced production of C₁₆-ceramide and apoptosis. Antifolate methotrexate (MTX), a drug commonly used in chemotherapy of several types of cancer, is a strong inhibitor of folate metabolism. Here we investigated whether this drug targets CerS6. We observed that CerS6 protein was markedly elevated in several cancer cell lines treated with MTX. In agreement with the enzyme elevation, its product C₁₆-ceramide was also strongly elevated, so as several other ceramide species. The increase in C₁₆-ceramide, however, was eliminated in MTX-treated cells lacking CerS6 through siRNA silencing, while the increase in other ceramides sustained. Furthermore, the siRNA silencing of CerS6 robustly protected A549 lung adenocarcinoma cells from MTX toxicity, while the silencing of another ceramide synthase, CerS4, which was also responsive to folate stress in our previous study, did not interfere with the MTX effect. The rescue effect of CerS6 silencing upon MTX treatment was further confirmed in HCT116 and HepG2 cell lines. Interestingly, CerS6 itself, but not CerS4, induced strong antiproliferative effect in several cancer cell lines if elevated by transient transfection. The effect of MTX on CerS6 elevation was likely p53 dependent, which is in agreement with the hypothesis that the protein is a transcriptional target of p53. In line with this notion, lometrexol, the antifolate inducing cytotoxicity through the p53-independent mechanism, did not affect CerS6 levels. We have also found that MTX induces the formation of ER aggregates, enriched with CerS6 protein. We further demonstrated that such aggregation requires CerS6 and suggests that it is an indication of ER stress. Overall, our study identified CerS6 and ceramide pathways as a novel MTX target.

Early and delayed intervention with rapamycin prevents NNK-induced lung adenocarcinoma in A/J mice

In tobacco-associated lung cancers, the protein kinase B/mammalian target of rapamycin (Akt/mTOR) pathway frequently is activated by nicotine and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The aim of the present study was to examine the effects of early or late intervention with rapamycin in NNK-induced lung adenoma and progression to adenocarcinoma in female A/J mice. At 7 weeks of age, 40 mice/each carcinogen group received one dose of 10 μmol NNK i.p. Three weeks later, the early intervention groups (25/group) were fed diets containing 0, 8 or 16 ppm rapamycin. The mice were sacrificed after 17 or 34 weeks of drug exposure and tumors were evaluated via histopathology. For late intervention (late adenoma and adenocarcinoma stage), groups of 15 mice were administered diets containing 8 or 16 ppm rapamycin starting 20 weeks after NNK treatment and continuing for 17 weeks before evaluation of tumor progression. Administration of 8 or 16 ppm rapamycin as an early or a late stage intervention significantly suppressed lung adenoma and adenocarcinoma formation (p<0.01-0.0001) after 17 or 34 weeks of exposure. The effect was more pronounced (>50‑60% tumor inihibition; p<0.0001) at the early intervention and the size of NNK-induced tumors decreased from >2.10 to <~0.75 mm3 (p=0.0056). Lung tumors harvested from mice exposed to rapamycin showed a significant decrease in p-mTOR, p-S6K1, PCNA and Bcl-xL as compared with controls in the early and late stage intervention studies. These observations suggest that rapamycin is highly effective even with administration after dysplastic adenoma or early adenocarcinoma stages and is useful for high-risk lung cancer patients.

Effect of (-)-epigallocatechin-3-O-gallate on autophagic signaling in HepG2 cells

AIM: To investigate the changes of autophagy in hepatocellular carcinoma (HCC) HepG2 cells in response to (-)-epigallocatechin-3-O-gallate (EGCG), and to explore its impact on cell proliferation and death.

METHODS: HepG2 cells were routinely cultured and re-plated in Dulbecco's modified eagle's medium (DMEM) in the presence of EGCG of different concentrations. Transmission electron microscopic technique was used to record the formation of autophagosomes in HepG2 cells. Real-time RT-PCR and Western blot were used to detect the mRNA and protein expression of autophagy-related genes, respectively. MTT and trypan blue assays were carried out to determine the cellular proliferation and death. Autophagic intervention experiment was performed to evaluate whether changes in autophagy are involved in the anti-cancer efficacy of EGCG in HCC.

RESULTS: The proliferation of HepG2 cells was significantly inhibited by EGCG and was negatively related to the concentrations of this compound (r = -0.9341, P < 0.001). Doses of EGCG that could effectively inhibit the proliferation of HepG2 cells significantly decreased the mRNA and protein expression of Beclin1 and Atg5, with increments of P62 named autophagic substrate as well as substantially reduced numbers of autophagasomes found in these cells. Moreover, up-regulating autophagy with rapamycin was found to apparently impair the effect of EGCG in killing HepG2 cells (t = 9.95, P < 0.01), while 3-MA, an autophagy inhibitor, dramatically exaggerated the anti-cancer effects of EGCG (t = 22.82, P < 0.01).

CONCLUSION: EGCG substantially inhibits cell proliferation and promotes cell death in HCC cells via down-regulation of autophagy, which indicates a novel critical pharmacological mechanism of EGCG for hepatoma therapy.

Ruthenium complex Λ-WH0402 induces hepatocellular carcinoma LM6 (HCCLM6) cell death by triggering the Beclin-1-dependent autophagy pathway

To evaluate the anticancer mechanism of the new ruthenium complex-Λ-WH0402 at the cellular level, the in vitro cytotoxicity of Λ-WH0402 was investigated on 10 human tumor cell lines. Λ-WH0402 was found to have higher anticancer activity than cisplatin toward human liver cancer HCCLM6 cells that have high tumor metastatic characteristics. Meanwhile, Λ-WH0402 showed an antimetastatic effect on HCCLM6 cells in vitro, mostly through its effect on cell adhesion, invasion and migration. In addition, Λ-WH0402 significantly reduced tumor metastasis to the lungs in orthotopic mouse hepatocellular cancer (HCC) models induced by HCCLM6 cells. Furthermore, Λ-WH0402 exerted an inhibitory effect on tumor cell growth and proliferation and induced dose-dependent cell cycle arrest in the S phase in HCCLM6 cells. Immunoblotting analysis showed that Λ-WH0402 not only decreased the expression of antiapoptotic protein Bcl-2 and nutrient-deprivation autophagy factor-1 (NAF-1), but also significantly increased the expression of Beclin-1 in HCCLM6 cells. More importantly, we identified that Λ-WH0402 treatment reduced the interaction between Bcl-2 and Beclin-1, and increased the expression of autophagic activation marker LC3B-II in HCCLM6 cells. On the whole, our results suggested that the anitcancer activity of Λ-WH0402 is mediated through promoting the Beclin-1-dependent autophagy pathway in HCCLM6 cells.

Sorafenib/regorafenib and lapatinib interact to kill CNS tumor cells

The present studies were to determine whether the multi-kinase inhibitor sorafenib or its derivative regorafenib interacted with the ERBB1/ERBB2 inhibitor lapatinib to kill CNS tumor cells. In multiple CNS tumor cell types sorafenib and lapatinib interacted in a greater than additive fashion to cause tumor cell death. Tumor cells lacking PTEN, and anoikis or lapatinib resistant cells were as sensitive to the drug combination as cells expressing PTEN or parental cells, respectively. Similar data were obtained using regorafenib. Treatment of brain cancer cells with [sorafenib + lapatinib] enhanced radiation toxicity. The drug combination increased the numbers of LC3-GFP vesicles; this correlated with a reduction in endogenous LC3II, and p62 and LAMP2 degradation. Knock down of Beclin1 or ATG5 significantly suppressed drug combination lethality. Expression of c-FLIP-s, BCL-XL, or dominant negative caspase 9 reduced drug combination toxicity; knock down of FADD or CD95 was protective. Expression of both activated AKT and activated MEK1 or activated mTOR was required to strongly suppress drug combination lethality. As both lapatinib and sorafenib are FDA approved agents, our data argue for further determination as to whether lapatinib and sorafenib is a useful glioblastoma therapy.

Development of autophagy inducers in clinical medicine

Defects in autophagy have been linked to a wide range of medical illnesses, including cancer as well as infectious, neurodegenerative, inflammatory, and metabolic diseases. These observations have led to the hypothesis that autophagy inducers may prevent or treat certain clinical conditions. Lifestyle and nutritional factors, such as exercise and caloric restriction, may exert their known health benefits through the autophagy pathway. Several currently available FDA-approved drugs have been shown to enhance autophagy, and this autophagy-enhancing action may be repurposed for use in novel clinical indications. The development of new drugs that are designed to be more selective inducers of autophagy function in target organs is expected to maximize clinical benefits while minimizing toxicity. This Review summarizes the rationale and current approaches for developing autophagy inducers in medicine, the factors to be considered in defining disease targets for such therapy, and the potential benefits of such treatment for human health.