A potential novel cancer immunotherapy: Agonistic anti-CD40 antibodies

CD40, a novel immunomodulatory cancer therapy target, is expressed by B cells, macrophages, and dendritic cells (DCs) and mediates cytotoxic T cell priming through the CD40 ligand. Some tumors show promising responses to monotherapy or combination therapy with agonistic anti-CD40 antibodies. The development of improved anti-CD40 antibodies makes CD40 activation an innovative strategy in cancer immunotherapy. In this review, we trace the history of CD40 research and summarize preclinical and clinical findings. We emphasize the ongoing development of improved anti-CD40 antibodies and explore strategies for effective combination therapies. Guided by predictive biomarkers, future research should identify patient populations benefiting the most from CD40 activation.

Nano-modified viruses prime the tumor microenvironment and promote the photodynamic virotherapy in liver cancer

BACKGROUND

As of 2020, hepatocellular carcinoma (HCC), a form of liver cancer, stood as the third most prominent contributor to global cancer-related mortality. Combining immune checkpoint inhibitors (ICI) with other therapies has shown promising results for treating unresectable HCC, offering new opportunities. Recombinant adeno-associated viral type 2 (AAV2) virotherapy has been approved for clinical use but it efficacy is stifled through systemic administration. On the other hand, iron oxide nanoparticles (ION) can be cleared via the liver and enhance macrophage polarization, promoting infiltration of CD8+ T cells and creating a more favorable tumor microenvironment for immunotherapy.

METHODS

To enhance the efficacy of virotherapy and promote macrophage polarization towards the M1-type in the liver, ION-AAV2 were prepared through the coupling of ION-carboxyl and AAV2-amine using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC)/N-hydroxysulfosuccinimide (Sulfo-NHS). Efficacy after systemic delivery of ION-AAV2 in an orthotopic HCC model was evaluated.

RESULTS

After 28 days, the tumor weight in mice treated with ION-AAV2 was significantly reduced by 0.56-fold compared to the control group. The ION-AAV2 treatment led to an approximate 1.80-fold increase in the level of tumor associated M1-type macrophages, while the number of M2-type macrophages was reduced by 0.88-fold. Moreover, a proinflammatory response increased the population of tumor-infiltrating CD8+ T cells in the ION-AAV2 group. This transformation converted cold tumors into hot tumors.

CONCLUSIONS

Our findings suggest that the conjugation of ION with AAV2 could be utilized in virotherapy while simultaneously exploiting macrophage-modulating cancer immunotherapies to effectively suppress HCC growth.

Anti-leukemia effects of omipalisib in acute myeloid leukemia: inhibition of PI3K/AKT/mTOR signaling and suppression of mitochondrial biogenesis

Omipalisib (GSK2126458), a potent dual PI3K/mTOR inhibitor, is reported to exhibit anti-tumor effect in several kinds of cancers. More than 50% of acute myeloid leukemia (AML) patients display a hyperactivation of PI3K/AKT/mTOR signaling. We investigated the anti-proliferative effect of omipalisib in AML cell lines with varied genetic backgrounds. The OCI-AML3 and THP-1 cell lines had a significant response to omipalisib, with IC50 values of 17.45 nM and 8.93 nM, respectively. We integrated transcriptomic profile and metabolomic analyses, and followed by gene set enrichment analysis (GSEA) and metabolite enrichment analysis. Our findings showed that in addition to inhibiting PI3K/AKT/mTOR signaling and inducing cell cycle arrest at the G0/G1 phase, omipalisib also suppressed mitochondrial respiration and biogenesis. Furthermore, omipalisib downregulated several genes associated with serine, glycine, threonine, and glutathione metabolism, and decreased their protein and glutathione levels. In vivo experiments revealed that omipalisib significantly inhibited tumor growth and prolonged mouse survival without weight loss. Gedatolisib and dactolisib, another two PI3K/mTOR inhibitors, exerted similar effects without affecting mitochondria biogenesis. These results highlight the multifaceted anti-leukemic effect of omipalisib, revealing its potential as a novel therapeutic agent in AML treatment.

Genomic and Transcriptomic Landscape of an Oral Squamous Cell Carcinoma Mouse Model for Immunotherapy

The immune checkpoint inhibitor (ICI), anti-programmed death-1 (anti-PD-1), has shown moderate efficacy in some patients with head and neck squamous cell carcinoma (HNSCC). Because of this, it is imperative to establish a mouse tumor model to explore mechanisms of antitumor immunity and to develop novel therapeutic options. Here, we examined the 4-nitroquinoline-1-oxide (4NQO)-induced oral squamous cell carcinoma (OSCC) model for genetic aberrations, transcriptomic profiles, and immune cell composition at different pathologic stages. Genomic exome analysis in OSCC-bearing mice showed conservation of critical mutations found in human HNSCC. Transcriptomic data revealed that a key signature comprised of immune-related genes was increased beginning at the moderate dysplasia stages. We first identified that macrophage composition in primary tumors differed across pathologic stages, leading to an oncogenic evolution through a change in the M1/M2 macrophage ratio during tumorigenesis. We treated the 4NQO-induced OSCC-bearing mice with anti-PD-1 and agonistic anti-CD40, which modulated multiple immune responses. The growth of tumor cells was significantly decreased by agonistic anti-CD40 by promoting an increase in the M1/M2 ratio. By examining cross-species genomic conservation in human and mouse tumors, our study demonstrates the molecular mechanisms underlying the development of OSCC and the regulation of contributing immune-related factors, and aims to facilitate the development of suitable ICI-based treatments for patients with HNSCC.

SN-38, an active metabolite of irinotecan, enhances anti-PD-1 treatment efficacy in head and neck squamous cell carcinoma

Anti-programmed cell death 1 (anti-PD-1) therapy shows definite but modest activity in patients with advanced/metastatic head and neck squamous cell carcinoma (HNSCC). Preliminary evidence suggests that SN-38, an activated form of irinotecan that increases expression of the transcription factor FoxO3a, can suppress programmed cell death ligand-1 (PD-L1) expression in breast and ovarian tumor models. We analyzed the SN-38-mediated activation of natural killer cells in vitro and explored the efficacy of SN-38 in combination with anti-PD-1 for treatment in vivo. In vitro, SN-38 enhanced the expression of FoxO3a and reduced the expression of c-Myc and PD-L1 dose-dependently in tumor cells. Low-dose SN-38 increased interferon-γ secretion by NK cells and promoted NK cell-mediated cytotoxicity in tumor cells. In vivo studies revealed that at non-cytotoxic drug concentrations, SN-38 significantly enhanced anti-PD-1 activity in suppressing murine tumor growth. We found increased NK cell and CD8⁺ T-cell infiltration in post-treatment tumors. RNA-seq analysis indicated that SN-38 increased the enrichment of immune cells and biological function genes related to the immune responses. SN-38 is a potentially beneficial adjunct to checkpoint inhibitor therapy in HNSCC. Further studies exploring its mechanism of action and possible applications are necessary. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Mouse Models for Immune Checkpoint Blockade Therapeutic Research in Oral Cancer

The most prevalent oral cancer globally is oral squamous cell carcinoma (OSCC). The invasion of adjacent bones and the metastasis to regional lymph nodes often lead to poor prognoses and shortened survival times in patients with OSCC. Encouraging immunotherapeutic responses have been seen with immune checkpoint inhibitors (ICIs); however, these positive responses to monotherapy have been limited to a small subset of patients. Therefore, it is urgent that further investigations into optimizing immunotherapies are conducted. Areas of research include identifying novel immune checkpoints and targets and tailoring treatment programs to meet the needs of individual patients. Furthermore, the advancement of combination therapies against OSCC is also critical. Thus, additional studies are needed to ensure clinical trials are successful. Mice models are advantageous in immunotherapy research with several advantages, such as relatively low costs and high tumor growth success rate. This review paper divided methods for establishing OSCC mouse models into four categories: syngeneic tumor models, chemical carcinogen induction, genetically engineered mouse, and humanized mouse. Each method has advantages and disadvantages that influence its application in OSCC research. This review comprehensively surveys the literature and summarizes the current mouse models used in immunotherapy, their advantages and disadvantages, and details relating to the cell lines for oral cancer growth. This review aims to present evidence and considerations for choosing a suitable model establishment method to investigate the early diagnosis, clinical treatment, and related pathogenesis of OSCC.

Effects of prophylactic high and low doses of corticosteroid on the efficacy of immune checkpoint blockade in murine hepatocellular carcinoma models

e14596

Background: Immune-related adverse events (irAEs) are major hurdle to immune checkpoint blockade (ICB). Corticosteroid (CS) is effective in controlling the majority of irAEs. Although recent studies suggested CS use does not jeopardize the anti-tumor efficacy of ICB, prophylactic use of CS remains prohibited with the concerns of attenuating efficacy of ICB. This study aimed to investigate the effects of CS premedication on the efficacy of ICB in murine hepatocellular carcinoma models. Methods: Anti-mCTLA-4 (9D9C, BMS) and anti-mPD-1 antibodies (4H2, ONO) were intraperitoneally (ip) administered to tumor-bearing mice (subcutaneous Hepa 1-6 model and orthotopic BNL 1MEA.7R.1 model) with or without dexamethasone (DEXA) premedication (10 and 200 μg, equivalent to minimal anti-inflammatory dosage and pulse therapy in human, respectively). Efficacy of ICB was evaluated as tumor shrinkage. Tumor-infiltrating lymphocytes (TILs) were isolated for single cell RNA-sequencing and effector function analysis through flow cytometry. Results: In the subcutaneous model, all tumors treated with ICB alone (N=7) or ICB plus DEXA 10 μg (N=5) completely regressed, but 1 out of 7 tumors treated with ICB plus DEXA 200 μg escaped. However, the tumor growth was not significantly different between groups ( P-value >0.05, multiple Mann-Whitney test). In the orthotopic model (N=5/group), the mean (± standard error) tumor weights on day 21 after tumor implantation for isotype control, ICB, ICB plus DEXA 10 μg and ICB plus DEXA 200 μg were 2.45 (± 0.54), 0.73 (± 0.18), 0.98 (± 0.65), and 0.69 (± 0.17) grams, respectively ( P-value >0.05, comparing ICB plus DEXA 10 or 200 μg with ICB). At transcriptomic level, premedication with either dosage of DEXA significantly reduced the percentage of effector memory cells and increased the percentage of exhausted effector cells in the CD8 TIL population, which appeared to counterbalance the effects of ICB. However, at protein level, premedication of DEXA 10 or 200 μg did not reduce the interferon-γ or granzyme B production of CD8 TILs in both models (Table). Conclusions: CS premedication did not attenuate the efficacy of ICB. Our study provides the scientific basis to evaluate the potential of prophylactic CS in preventing ICB-induced irAEs in clinical studies.[Table: see text]

Synergistic Effect of Repolarization of M2 to M1 Macrophages Induced by Iron Oxide Nanoparticles Combined with Lactate Oxidase

Metabolic reprogramming of tumors with the accompanying reprogramming of glucose metabolism and production of lactate accumulation is required for the subsequent development of tumors. Recent evidence has indicated that tumor-secreted lactate can promote an oncolytic immune microenvironment within the tumor. Furthermore, tumor-secreted lactate directly induces polarization of tumor-supportive M2 macrophages. However, oxidized tumor-secreted lactate in the tumor microenvironment can be exploited. Iron oxide nanoparticles have shown promising anticancer potential by activating tumor-suppressing macrophages. Furthermore, lactate oxidase (LOX) generally oxidizes tumor-secreted lactate and subsequently converts to pyruvate. Particularly, the ratio of M2 macrophages to M1 macrophages corresponds with tumor growth. In this study, we present iron oxide nanoparticles with carboxylic acid combined with LOX that enhance antitumor efficacy as a synergistic effect on the repolarization of tumor-supportive M2 macrophages to tumor-suppressive M1 macrophages in a tumor microenvironment. After M2 macrophages treated with iron oxide nanoparticles were combined with LOX, the ratio of M1 macrophages was significantly greater than iron oxide nanoparticles alone or with LOX alone. It is concluded that the inhibition of cancer cell proliferation by ratio of M1 macrophages was observed. This study suggests that the iron oxide nanoparticles combined with LOX could be potentially used for potentiating immune checkpoint inhibitor therapies for cancer treatment.

Exploring Markers of Exhausted CD8 T Cells to Predict Response to Immune Checkpoint Inhibitor Therapy for Hepatocellular Carcinoma

BACKGROUND

Reversal of CD8 T-cell exhaustion was considered a major antitumor mechanism of anti-programmed cell death-1 (PD-1)/ anti-programmed death ligand-1 (PD-L1)-based immune checkpoint inhibitor (ICI) therapy.

OBJECTIVES

The aim of this study was to identify markers of T-cell exhaustion that is best associated with ICI treatment efficacy for advanced hepatocellular carcinoma (HCC).

METHODS

Immune cell composition of archival tumor samples was analyzed by transcriptomic analysis and multiplex immunofluorescence staining.

RESULTS

HCC patients with objective response after anti-PD-1/anti-PD-L1-based ICI therapy (n = 42) had higher expression of genes related to T-cell exhaustion. A 9-gene signature (LAG3, CD244, CCL5, CXCL9, CXCL13, MSR1, CSF3R, CYBB, and KLRK1) was defined, whose expression was higher in patients with response to ICI therapy, correlated with density of CD8⁺LAG3⁺ cells in tumor microenvironment, and independently predicted better progression-free and overall survival. This 9-gene signature had similar predictive values for patients who received single-agent or combination ICI therapy and was not associated with prognosis in HCC patients who received surgery, suggesting that it may outperform other T-cell signatures for predicting efficacy of ICI therapy for HCC. For HCC patients who underwent surgery for both the primary liver and metastatic lung tumors (n = 31), lung metastatic HCC was associated with a higher exhausted CD8 T-cell signature, consistent with prior observation that patients with lung metastatic HCC may have higher probability of response to ICI therapy.

CONCLUSIONS

CD8 T-cell exhaustion in tumor microenvironment may predict better efficacy of ICI therapy for HCC.

Cabozantinib promotes erythroid differentiation in K562 erythroleukemia cells through global changes in gene expression and JNK activation

Cabozantinib is a potent tyrosine kinase inhibitor with multiple targets including MET, VEGFR2, RET, KIT, and FLT3. Cabozantinib is widely used for the treatment of medullary thyroid cancer and renal cell carcinoma. We recently suggested cabozantinib as a potential therapeutic alternative for acute myeloid leukemia (AML) patients with FLT3-internal tandem duplication (FLT3-ITD). Here, we report that cabozantinib can promote differentiation in erythroid leukemia cells. We found that K562 erythroid leukemia cells treated with 1 μM cabozantinib for 72 h underwent erythroid lineage differentiation. Transcriptomic analysis revealed that various pathways associated with heme biosynthesis, hemoglobin production, and GATA1 targets were upregulated, whereas cell survival pathways were downregulated. Further examination revealed that cabozantinib-induced erythroid differentiation is at least in part regulated by JNK activation and phosphorylation. Levels of phosphorylated BCR-ABL, AKT, STAT5, ERK, and p38 also decreased following cabozantinib treatment. Therefore, we indicate that cabozantinib has dual functions. First, it induces K562 cell differentiation toward the erythroid lineage by upregulating heme biosynthesis, globin synthesis, and erythroid-associated reactions. Second, cabozantinib inhibits K562 cell proliferation by inhibiting the phosphorylation of BCR-ABL and the downstream MAPK, PI3K-AKT, and JAK-STAT signaling pathways.

Regorafenib enhances antitumor immunity via inhibition of p38 kinase/Creb1/Klf4 axis in tumor-associated macrophages

BACKGROUND

Regorafenib and other multikinase inhibitors may enhance antitumor efficacy of anti-program cell death-1 (anti-PD1) therapy in hepatocellular carcinoma (HCC). Its immunomodulatory effects, besides anti-angiogenesis, were not clearly defined.

METHODS

In vivo antitumor efficacy was tested in multiple syngeneic liver cancer models. Murine bone marrow-derived macrophages (BMDMs) were tested in vitro for modulation of polarization by regorafenib and activation of cocultured T cells. Markers of M1/M2 polarization were measured by quantitative reverse transcription PCR (RT-PCR), arginase activity, flow cytometry, and ELISA. Knockdown of p38 kinase and downstream Creb1/Klf4 signaling on macrophage polarization were confirmed by using knockdown of the upstream MAPK14 kinase, chemical p38 kinase inhibitor, and chromatin immunoprecipitation.

RESULTS

Regorafenib (5 mg/kg/day, corresponding to about half of human clinical dosage) inhibited tumor growth and angiogenesis in vivo similarly to DC-101 (anti-VEGFR2 antibody) but produced higher T cell activation and M1 macrophage polarization, increased the ratio of M1/M2 polarized BMDMs and proliferation/activation of cocultured T cells in vitro, indicating angiogenesis-independent immunomodulatory effects. Suppression of p38 kinase phosphorylation and downstream Creb1/Klf4 activity in BMDMs by regorafenib reversed M2 polarization. Regorafenib enhanced antitumor efficacy of adoptively transferred antigen-specific T cells. Synergistic antitumor efficacy between regorafenib and anti-PD1 was associated with multiple immune-related pathways in the tumor microenvironment.

CONCLUSION

Regorafenib may enhance antitumor immunity through modulation of macrophage polarization, independent of its anti-angiogenic effects. Optimization of regorafenib dosage for rational design of combination therapy regimen may improve the therapeutic index in the clinic.

Development of a PD-L1-Expressing Orthotopic Liver Cancer Model: Implications for Immunotherapy for Hepatocellular Carcinoma

BACKGROUND

Anti-programmed cell death-1(anti-PD1) treatment has shown promising antitumor efficacy in patients with advanced hepatocellular carcinoma (HCC). This study sought to explore the functional significance of programmed death ligand-1 (PD-L1) expression in tumor cells in the tumor microenvironment.

METHODS

The mouse liver cancer cell line BNL-MEA was transfected with PD-L1 plasmids and stable clones expressing PD-L1 were selected. An orthotopic HCC model was generated by implanting the cells into the subcapsular space of BALB/c mice. Cell growth features were measured by proliferation assay, colony formation, flow cytometry (in vitro), ultrasonography, and animal survival (in vivo). The changes in T-cell function were examined by cytokine assay, expression of T-cell related genes, and flow cytometry. The efficacy of anti-PD1 therapy was compared between the parental and PD-L1-expressing tumors.

RESULTS

PD-L1 expression did not affect growth characteristics of BNL-MEA cells but downregulated the expression of genes related to T-cell activation in the tumor microenvironment. Co-culture of PD-L1-expressing BNL-MEA cells with CD8+ T cells reduced T-cell proliferation and expression of cytokines IFNγ and TNFα. Tumors with PD-L1 expression showed better response to anti-PD1 therapy and depletion of CD8+ T cells abolished the antitumor effect. The difference in treatment response between parental and PD-L1-expressing tumors disappeared when a combination of anti-PD1 and sorafenib was given.

CONCLUSIONS

PD-L1 expression in HCC cells may inhibit T-cell function in the liver tumor microenvironment. Anti-PD1 therapy appeared more effective in PD-L1-expressing than nonexpressing tumors, but the difference was diminished by the addition of sorafenib.

TARBP2-mediated destabilization of Nanog overcomes sorafenib resistance in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a lethal human malignancy and a leading cause of cancer‐related death worldwide. Patients with HCC are often diagnosed at an advanced stage, and the prognosis is usually poor. The multikinase inhibitor sorafenib is the first‐line treatment for patients with advanced HCC. However, cases of primary or acquired resistance to sorafenib have gradually increased, leading to a predicament in HCC therapy. Thus, it is critical to investigate the mechanism underlying sorafenib resistance. Transactivation response element RNA‐binding protein 2 (TARBP2) is a multifaceted miRNA biogenesis factor that regulates cancer stem cell (CSC) properties. The tumorigenicity and drug resistance of cancer cells are often enhanced due to the acquisition of CSC features. However, the role of TARBP2 in sorafenib resistance in HCC remains unknown. Our results demonstrate that TARBP2 is significantly downregulated in sorafenib‐resistant HCC cells. The TARBP2 protein was destabilized through autophagic–lysosomal proteolysis, thereby stabilizing the expression of the CSC marker protein Nanog, which facilitates sorafenib resistance in HCC cells. In summary, here we reveal a novel miRNA‐independent role of TARBP2 in regulating sorafenib resistance in HCC cells.

Immunomodulatory Effects of Current Targeted Therapies on Hepatocellular Carcinoma: Implication for the Future of Immunotherapy

Multikinase inhibitors with antiangiogenic properties used to be standard therapy for patients with advanced hepatocellular carcinoma (HCC). Recently, several antiangiogenic agents (lenvatinib, cabozantinib, and ramucirumab) have demonstrated antitumor activity for advanced HCC in randomized controlled trials. However, the landscape of drug development for HCC may change dramatically with the advent of immune checkpoint inhibitor therapy, particularly the anti-programmed cell death-1 (anti-PD1) agents. In addition, early-phase clinical trials of combination of anti-PD-1 and antiangiogenic agents have shown very promising anti-tumor activity in patients with advanced HCC. Therefore, the critical research questions at present are whether this combination strategy will be the next generation of standard therapy and which antiangiogenic agents will be the optimal partner for the combination. All of the 4 multikinase inhibitors for HCC (sorafenib, regorafenib, lenvatinib, and cabozantinib) have been reported to have immune modulatory effects. The authors systematically reviewed the pre-clinical evidence of their immune modulatory effects to explore whether these effects were mediated by angiogenesis inhibition or by other "off-target" effects on the tumor microenvironment. Studies of sorafenib comprised the majority (58 of the 71) of the research articles reviewed. Potentially beneficial effects on anti-tumor immunity may result from increased M1 polarization of macrophages and stimulation of CD8 T cell function. On the other hand, high dosage of the kinase inhibitors in pre-clinical models and hypoxia associated with angiogenesis may contribute to immune suppression in the tumor microenvironment. Sorafenib and other multikinase inhibitors may promote anti-tumor immunity through modulation of multiple immune cell types as well as the tumor microenvironment. The optimal immune modulatory dosage should be defined to facilitate design of future combination regimens.

Simultaneous visualization of the subfemtomolar expression of microRNA and microRNA target gene using HILO microscopy

In this study, we propose a sensitive imaging method for the direct probing of miR-10b and its target in fixed cells.

The family of microRNAs (miRNAs) not only plays an important role in gene regulation but is also useful for the diagnosis of diseases. A reliable method with high sensitivity may allow researchers to detect slight fluctuations in ultra-trace amounts of miRNA. In this study, we propose a sensitive imaging method for the direct probing of miR-10b (miR-10b-3p, also called miR-10b*) and its target (HOXD10 mRNA) in fixed cells based on the specific recognition of molecular beacons combined with highly inclined and laminated optical sheet (HILO) fluorescence microscopy. The designed dye-quencher-labelled molecular beacons offer excellent efficiencies of fluorescence resonance energy transfer that allow us to detect miRNA and the target mRNA simultaneously in hepatocellular carcinoma cells using HILO fluorescence microscopy. Not only can the basal trace amount of miRNA be observed in each individual cell, but the obtained images also indicate that this method is useful for monitoring the fluctuations in ultra-trace amounts of miRNA when the cells are transfected with a miRNA precursor or a miRNA inhibitor (anti-miR). Furthermore, a reasonable causal relation between the miR-10b and HOXD10 expression levels was observed in miR-10b* precursor-transfected cells and miR-10b* inhibitor-transfected cells. The trends of the miRNA alterations obtained using HILO microscopy completely matched the RT-qPCR data and showed remarkable reproducibility (the coefficient of variation [CV] = 0.86%) and sensitivity (<1.0 fM). This proposed imaging method appears to be useful for the simultaneous visualisation of ultra-trace amounts of miRNA and target mRNA and excludes the procedures for RNA extraction and amplification. Therefore, the visualisation of miRNA and the target mRNA should facilitate the exploration of the functions of ultra-trace amounts of miRNA in fixed cells in biological studies and may serve as a powerful tool for diagnoses based on circulating cancer cells.

Growth arrest DNA damage-inducible gene 45 gamma expression as a prognostic and predictive biomarker in hepatocellular carcinoma

Growth arrest DNA damage-inducible gene 45 (GADD45) family proteins play a crucial role in regulating cellular stress responses and apoptosis. The present study explored the prognostic and predictive role of GADD45γ in hepatocellular carcinoma (HCC) treatment. GADD45γ expression in HCC cells was examined using quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. The control of GADD45γ transcription was examined using a luciferase reporter assay and chromatin immunoprecipitation. The in vivo induction of GADD45γ was performed using adenoviral transfer. The expression of GADD45γ in HCC tumor tissues from patients who had undergone curative resection was measured using qRT-PCR. Sorafenib induced expression of GADD45γ mRNA and protein, independent of its RAF kinase inhibitor activity. GADD45γ induction was more prominent in sorafenib-sensitive HCC cells (Huh-7 and HepG2, IC₅₀ 6–7 μM) than in sorafenib-resistant HCC cells (Hep3B, Huh-7R, and HepG2R, IC₅₀ 12–15 μM). Overexpression of GADD45γ reversed sorafenib resistance in vitro and in vivo, whereas GADD45γ expression knockdown by using siRNA partially abrogated the proapoptotic effects of sorafenib on sorafenib-sensitive cells. Overexpression of survivin in HCC cells abolished the antitumor enhancement between GADD45γ overexpression and sorafenib treatment, suggesting that survivin is a crucial mediator of antitumor effects of GADD45γ. GADD45γ expression decreased in tumors from patients with HCC who had undergone curative surgery, and low GADD45γ expression was an independent prognostic factor for poor survival, in addition to old age and vascular invasion. The preceding data indicate that GADD45γ suppression is a poor prognostic factor in patients with HCC and may help predict sorafenib efficacy in HCC.

Cabozantinib is selectively cytotoxic in acute myeloid leukemia cells with FLT3-internal tandem duplication (FLT3-ITD)

Cabozantinib is an oral multikinase inhibitor that exhibits anti-tumor activity in several cancers. We found that cabozantinib was significantly cytotoxic to MV4-11 and Molm-13 cells that harbored FLT3-ITD, resulting in IC50 values of 2.4 nM and 2.0 nM, respectively. However, K562, OCI-AML3 and THP-1 (leukemia cell lines lacking FLT3-ITD) were resistant to cabozantinib, showing IC50 values in the micromolar range. Cabozantinib arrested MV4-11 cell growth at the G0/G1 phase within 24 h, which was associated with decreased phosphorylation of FLT3, STAT5, AKT and ERK. Additionally, cabozantinib induced MV4-11 cell apoptosis in a dose-dependent manner (as indicated by annexin V staining and high levels of cleaved caspase 3 and PARP-1), down-regulated the anti-apoptotic protein survivin and up-regulated the pro-apoptotic protein Bak. Thus, cabozantinib is selectively cytotoxic to leukemia cells with FLT3-ITD, causing cell-cycle arrest and apoptosis. In mouse xenograft model, cabozantinib significantly inhibited MV4-11 and Molm-13 tumor growth at a dosage of 10 mg/kg and showed longer survival rate. Clinical trials evaluating the efficacy of cabozantinib in acute myeloid leukemia (AML) with FLT3-ITD are warranted.

Abstract B136: Development of PD-L1/L2 over-expressing mouse liver cancer models to test the efficacy of anti-PD1 therapy for hepatocellular carcinoma

Anti-PD1 therapy has shown promising anti-tumor activities in multiple cancer types, including hepatocellular carcinoma (HCC), and PD-L1 expression in tumor cells was considered a potential predictive marker for treatment efficacy. The present study explored whether PD-L1/L2 expression may affect treatment efficacy of anti-PD1 therapy for HCC. PD-L1 (MR203953; Origene Technologies, Rockville, MD) or PD-L2 (MR222499; Origene Technologies) was transfected into the BNL-MEA murine liver cancer cell lines and stable clones were selected. Effects of PDL1/L2 over-expression were confirmed by Western blotting and immunofluorescence assay. Effects of PDL1/L2 over-expression on in vitro growth characteristics were compared by MTT, colony formation, and 3-D culture assays. Orthotopic liver cancer models were established by sub-capsular injection of parental or transfected cancer cells into the left lobe of mouse liver. The anti-tumor efficacy of anti-mouse PD1 therapy (clone 4H2, Ono Pharmaceutical Co), 0.2 mg by intraperitoneal injection on day 5, 8, 11, 14, and 17 after tumor implantation, was measured by change in tumor volume using the orthotopic liver cancer models. Distribution of T-cell sub-populations in tumor-infiltrating lymphocytes (TILs) after treatment were measured by flow cytometry.

The growth characteristics of parental and PD-L1/L2-expressing BNL-MEA cells did not differ significantly, as measured by MTT, colony formation, and 3-D culture assays. Survival of animals bearing the orthotopic liver tumor with or without PD-L1/L2 over-expression was also similar. Anti-PD1 therapy appeared more efficacious in PD-L1-over-expressing liver cancer models than the parental or PD-L2-over-expressing models. Distinctive TILs distribution patterns between parental and PD-L1/L2 over-expressing liver cancer models were found after anti-PD1 therapy.

Conclusions: The PD-L1/L2 expressing liver cancer models may help evaluate the efficacy and mechanisms of action of anti-PD1 therapy for HCC.

Citation Format: Da-Liang Ou, Shu-Ching Chen, Yu-Chia Su, Ann-Lii Cheng, Chiun Hsu. Development of PD-L1/L2 over-expressing mouse liver cancer models to test the efficacy of anti-PD1 therapy for hepatocellular carcinoma. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B136.

Cyclin E1 Inhibition can Overcome Sorafenib Resistance in Hepatocellular Carcinoma Cells Through Mcl-1 Suppression

PURPOSE

To clarify the effects of cyclin E1 suppression on antitumor efficacy of sorafenib in hepatocellular carcinoma cells and to explore the potential of combining sorafenib with cyclin-dependent kinase (CDK) inhibition in therapy.

EXPERIMENTAL DESIGN

The effects of cyclin E1 suppression on sorafenib-induced apoptosis were tested in both sorafenib-sensitive (Huh-7 and HepG2, IC50 5-6 μmol/L) and sorafenib-resistant (Huh-7R and HepG2R, IC50 14-15 μmol/L) hepatocellular carcinoma cells. The activity of pertinent signaling pathways and the expression of cell cycle and apoptosis-related proteins were measured using Western blotting. Efficacy of sorafenib combined with the pan-CDK inhibitor flavopiridol was tested both in vitro and in xenograft experiments. The pertinent downstream mediators of antitumor efficacy were tested in transient transfection and RNA interference experiments.

RESULTS

Cyclin E1 mRNA and protein expressions were suppressed after sorafenib treatment in sorafenib-sensitive but not in sorafenib-resistant hepatocellular carcinoma cells. Changes in cyclin E2 or D1 were not correlated with sorafenib sensitivity. The knockdown of cyclin E1 expression reversed the resistance of hepatocellular carcinoma cells to sorafenib in terms of cell growth and apoptosis induction, whereas the overexpression of cyclin E1 increased the resistance to sorafenib. The growth-inhibitory and apoptosis-inducing effects of sorafenib were enhanced by flavopiridol, and Mcl-1 suppression was determined to play a critical role in mediating this enhancing effect.

CONCLUSIONS

The cyclin E1 suppression in hepatocellular carcinoma cells may serve as a pharmacodynamic biomarker for predicting sorafenib efficacy. The combination of sorafenib and CDK inhibitors may improve the efficacy of sorafenib in hepatocellular carcinoma. Clin Cancer Res; 22(10); 2555-64. ©2015 AACR.

Zebrafish as a disease model for studying human hepatocellular carcinoma

Liver cancer is one of the world’s most common cancers and the second leading cause of cancer deaths. Hepatocellular carcinoma (HCC), a primary hepatic cancer, accounts for 90%-95% of liver cancer cases. The pathogenesis of HCC consists of a stepwise process of liver damage that extends over decades, due to hepatitis, fatty liver, fibrosis, and cirrhosis before developing fully into HCC. Multiple risk factors are highly correlated with HCC, including infection with the hepatitis B or C viruses, alcohol abuse, aflatoxin exposure, and metabolic diseases. Over the last decade, genetic alterations, which include the regulation of multiple oncogenes or tumor suppressor genes and the activation of tumorigenesis-related pathways, have also been identified as important factors in HCC. Recently, zebrafish have become an important living vertebrate model organism, especially for translational medical research. In studies focusing on the biology of cancer, carcinogen induced tumors in zebrafish were found to have many similarities to human tumors. Several zebrafish models have therefore been developed to provide insight into the pathogenesis of liver cancer and the related drug discovery and toxicology, and to enable the evaluation of novel small-molecule inhibitors. This review will focus on illustrative examples involving the application of zebrafish models to the study of human liver disease and HCC, through transgenesis, genome editing technology, xenografts, drug discovery, and drug-induced toxic liver injury.

MK-2206 induces apoptosis of AML cells and enhances the cytotoxicity of cytarabine

Genetic alterations in the PI3K/AKT cascade have been linked to various human cancers including acute myeloid leukemia (AML) and have emerged to be promising targets for treatment. In this study, we explored the molecular mechanism and clinical implication of a specific allosteric AKT inhibitor, MK-2206, in the treatment of AML. Four leukemia cell lines, MV-4-11, MOLM-13, OCI/AML3, and U937, were used. Apoptosis and cell cycle distribution were determined by flow cytometry analysis. Expression of anti-apoptotic protein family and glycogen synthase kinase 3β (GSK3β) signaling was determined by western blotting. Drug combination effects of MK-2206 with cytarabine were evaluated by cell proliferation assay, and the combination index values were calculated by CompuSyn software. MK-2206 had no effect on normal peripheral blood mononuclear cells, but induced G1-phase arrest and apoptosis in leukemia cells. Among anti-apoptotic Bcl-2 family members, only myeloid cell leukemia-1 (Mcl-1) was significantly suppressed. Mcl-1 suppression by MK-2206 was closely associated with decreased GSK3β phosphorylation at Ser9, an event leads to GSK3β activation. Furthermore, the effect of MK-2206 on Mcl-1 downregulation was abolished by GSK3β inhibitor, lithium chloride and proteasome inhibitor, MG-132, suggesting that MK-2206 acted through a GSK3β-mediated, proteasome-dependent protein degradation. In addition, co-administration of MK-2206 with cytarabine could enhance the cytotoxic efficacy of cytarabine in leukemia cell lines. In conclusion, we have demonstrated that MK-2206 is an active agent in AML and its efficacy as in combination with cytarabine is implicated.

H3K9 histone methyltransferase, KMT1E/SETDB1, cooperates with the SMAD2/3 pathway to suppress lung cancer metastasis

Aberrant histone methylation is a frequent event during tumor development and progression. KMT1E (also known as SETDB1) is a histone H3K9 methyltransferase that contributes to epigenetic silencing of both oncogenes and tumor suppressor genes in cancer cells. In this report, we demonstrate that KMT1E acts as a metastasis suppressor that is strongly downregulated in highly metastatic lung cancer cells. Restoring KMT1E expression in this setting suppressed filopodia formation, migration, and invasive behavior. Conversely, loss of KMT1E in lung cancer cells with limited metastatic potential promoted migration in vitro and restored metastatic prowess in vivo. Mechanistic investigations indicated that KMT1E cooperates with the TGFβ-regulated complex SMAD2/3 to repress metastasis through ANXA2. Together, our findings defined an essential role for the KMT1E/SMAD2/3 repressor complex in TGFβ-mediated lung cancer metastasis.

Potential synergistic anti-tumor activity between lenalidomide and sorafenib in hepatocellular carcinoma

BACKGROUND AND AIM

The immune modulatory drug lenalidomide has shown promising anti-tumor activity in a clinical trial of patients with advanced hepatocellular carcinoma (HCC). The present study explored whether lenalidomide can enhance the anti-tumor activity of sorafenib, the standard molecular targeted therapy for HCC.

METHODS

The anti-tumor efficacy of single-agent or combination treatment was measured by change in tumor volume and animal survival using an orthotopic liver cancer model. Distribution of T-cell subpopulations in tumor-infiltrating lymphocytes (TILs) and splenocytes derived from tumor-implanted mice was measured by flow cytometry. Depletion of relevant T-cell subpopulations or cytokines was done by co-administration of relevant antibodies with study drug treatment. Tumor cell apoptosis and tumor angiogenesis were measured by transferase deoxytidyl uridine end labeling assay and immunohistochemical study, respectively.

RESULTS

Combination of sorafenib and lenalidomide produced significant synergistic anti-tumor efficacy in terms of tumor growth delay and animal survival. This synergistic effect was associated with a significant increase in interferon-γ expressing CD8(+) lymphocytes in TILs and a significantly higher number of granzyme- or perforin-expressing CD8(+) T cells, compared with vehicle- or single-agent treatment groups. Combination treatment significantly increased apoptotic tumor cells and vascular normalization in tumor tissue. The synergistic anti-tumor effect was abolished after CD8 depletion.

CONCLUSIONS

Lenalidomide can enhance the anti-tumor effects of sorafenib in HCC through its immune modulatory effects, and CD8(+) TILs play an important role in the anti-tumor synergism.

Abstract 2522: Development of GADD45β (growth arrest DNA damage-inducible gene 45 beta) agonists for the treatment of hepatocellular carcinoma (HCC)

Induction of GADD45β expression, which is associated with cellular stress response and apoptosis regulation, in HCC cells was found to correlate with sensitivity of sorafenib, the standard molecular targeted therapy for advanced HCC. In this study, we use this GADD45β induction as a screening platform to identify novel agents for HCC treatment from sorafenib derivatives that lack RAF kinase inhibition activity. GADD45β expression in Huh-7 cells was measured by quantitative RT-PCR. Cell viability was examined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was examined by flow cytometry. Signal transduction pathways in cells were assessed by western blotting. In vivo anti-tumor efficacy was tested in mouse xenograft models using Huh7 and Huh7R cells, the latter had acquired resistance to sorafenib. Pharmacokinetic studies were done in Sprague-Dawley rat model. The compound SC-20, which had a N-(4-(quinolin-4-yloxy)phenyl)benzamide scaffold, showed greater GADD45β induction than other derivatives. The nitro group on the quinolone ring of SC-20 was considered important in GADD45β induction. SC-20 induced more prominent apoptosis and inhibition of proliferation in Huh7 cells than sorafenib, independent of MEK/ERK signaling activity in Huh7 cells. SC-20 showed more prominent GADD45β induction and better antitumor activity than sorafenib in both Huh-7 and Huh7R xenograft models and good safety. Pharmacokinetic studies indicated that SC-20 had long plasma half-life (22.5 ± 0.51 hours), low water solubility, high (&gt; 99%) plasma protein binding, and inhibited CYP2C9 and 2C19. GADD45β agonists warrant further development for HCC treatment. (supported by NSC 101-2325-B-002 -039, NSC 101-2321-B-002 -014, NSC 102-2325-B-002 -038)

Citation Format: Chiun Hsu, Da-Liang Ou, Kuen-Feng Chen, Zhong-Zhe Lin, Ann-Lii Cheng, Chung-Wai Shiau. Development of GADD45β (growth arrest DNA damage-inducible gene 45 beta) agonists for the treatment of hepatocellular carcinoma (HCC). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2522. doi:10.1158/1538-7445.AM2014-2522

Vertical blockade of the IGFR- PI3K/Akt/mTOR pathway for the treatment of hepatocellular carcinoma: the role of survivin

BACKGROUND

To explore whether combining inhibitors that target the insulin-like growth factor receptor (IGFR)/PI3K/Akt/mTOR signaling pathway (vertical blockade) can improve treatment efficacy for hepatocellular carcinoma (HCC).

METHODS

HCC cell lines (including Hep3B, Huh7, and PLC5) and HUVECs (human umbilical venous endothelial cells) were tested. The molecular targeting therapy agents tested included NVP-AEW541 (IGFR kinase inhibitor), MK2206 (Akt inhibitor), BEZ235 (PI3K/mTOR inhibitor), and RAD001 (mTOR inhibitor). Potential synergistic antitumor effects were tested by median dose-effect analysis in vitro and by xenograft HCC models. Apoptosis was analyzed by flow cytometry (sub-G1 fraction analysis) and Western blotting. The activities of pertinent signaling pathways and expression of apoptosis-related proteins were measured by Western blotting.

RESULTS

Vertical blockade induced a more sustained inhibition of PI3K/Akt/mTOR signaling activities in all the HCC cells and HUVEC tested. Synergistic apoptosis-inducing effects, however, varied among different cell lines and drug combinations and were most prominent when NVP-AEW541 was combined with MK2206. Using an apoptosis array, we identified survivin as a potential downstream mediator. Over-expression of survivin in HCC cells abolished the anti-tumor synergy between NVP-AEW541 and MK2206, whereas knockdown of survivin improved the anti-tumor effects of all drug combinations tested. In vivo by xenograft studies confirmed the anti-tumor synergy between NVP-AEW541 and MK2206 and exhibited acceptable toxicity profiles.

CONCLUSIONS

Vertical blockade of the IGFR/PI3K/Akt/mTOR pathway has promising anti-tumor activity for HCC. Survivin expression may serve as a biomarker to predict treatment efficacy.

Potentiating the efficacy of molecular targeted therapy for hepatocellular carcinoma by inhibiting the insulin-like growth factor pathway

Insulin-like growth factor (IGF) signaling pathway is an important regulatory mechanism of tumorigenesis and drug resistance in many cancers. The present study explored the potential synergistic effects between IGF receptor (IGFR) inhibition and other molecular targeted agents (MTA) in HCC cells. HCC cell lines (Hep3B, PLC5, and SK-Hep1) and HUVECs were tested. The MTA tested included sorafenib, sunitinib, and the IGFR kinase inhibitor NVP-AEW541. The potential synergistic antitumor effects were tested by median dose effect analysis and apoptosis assay in vitro and by xenograft models in vivo. The activity and functional significance of pertinent signaling pathways and expression of apoptosis-related proteins were measured by RNA interference and Western blotting. We found that IGF can activate IGFR and downstream AKT signaling activities in all the HCC cells tested, but the growth-stimulating effect of IGF was most prominent in Hep3B cells. NVP-AEW541 can abrogate IGF-induced activation of IGFR and AKT signaling in HCC cells. IGF can increase the resistance of HCC cells to sunitinib. The apoptosis-inducing effects of sunitinib, but not sorafenib, were enhanced when IGFR signaling activity was inhibited by NVP-AEW541 or IGFR knockdown. Chk2 kinase activation was found contributory to the synergistic anti-tumor effects between sunitinib and IGFR inhibition. Our data indicate that the apoptosis-potentiating effects of IGFR inhibition for HCC may be drug-specific. Combination therapy of IGFR inhibitors with other MTA may improve the therapeutic efficacy in HCC.

Abstract B10: Potential synergistic antitumor activity between sorafenib and lenalidomide in an orthotopic murine liver cancer model

The immune modulatory drug lenalidomide has shown promising anti-tumor activity in a clinical trial of patients with advanced hepatocellular carcinoma (HCC). The present study explored whether lenalidomide can enhance the anti-tumor activity of sorafenib, the standard molecular targeted therapy for HCC. An orthotopic liver cancer model was developed by injecting the BNL liver cancer cells (from ATCC) into the liver capsule of BALB/c mice. Mice were treated by sorafenib by daily gavage or lenalidomide by daily intra-peritoneal injection, and the anti-tumor efficacy of single-agent or combination treatment was measured by change in tumor volume and animal survival. The number of IFN-γ expressing T-cell sub-populations in tumor-infiltrating lymphocytes (TILs) and the number of IFN-γ expressing tumors-specific CD8+ T cells in splenocytes derived from tumor-implanted mice were measured by flow cytometry. Depletion of relevant T cell sub-populations or cytokines was done by co-administration of relevant antibodies with study drug treatment. TUNEL assay and immunohistochemical study on tumor tissues were done to measure apoptosis and to explore potential biomarkers (Ki67, CD31). Combination of sorafenib (5 mg/kg/day) and lenalidomide (50 mg/kg/day) produced significant synergistic anti-tumor efficacy in terms of tumor growth delay and animal survival. This synergistic effect was associated with a significant increase in IFN-γ expressing CD8+ lymphocytes in TILs and splenocytes. In addition, TILs derived from mice in the combination treatment group had higher number of granzyme- or perforin- expressing CD8+ T cells, compared with vehicle- or single-agent-treatment groups. Combination treatment was associated with a significant increase in apoptotic tumor cells and decrease in microvessel density in tumor tissue. Finally, the synergistic anti-tumor effect was abolished after CD8 depletion. The combination treatment was well tolerated except that leucopenia was common. Our data indicate that lenalidomide can enhance the anti-tumor effects of sorafenib in HCC through its immune modulatory effects and CD8+ T cells play an important role in the anti-tumor synergism. (supported by grants NSC 101-2321-B-002 -014 and NSC 101-2314-B-002-162)

Citation Format: Chun-Jung Chang, Da-Liang Ou, Yi-Jang Lin, Ann-Lii Cheng, Chiun Hsu. Potential synergistic antitumor activity between sorafenib and lenalidomide in an orthotopic murine liver cancer model. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B10.

KRAS mutation is a predictor of oxaliplatin sensitivity in colon cancer cells

Molecular biomarkers to determine the effectiveness of targeted therapies in cancer treatment have been widely adopted in colorectal cancer (CRC), but those to predict chemotherapy sensitivity remain poorly defined. We tested our hypothesis that KRAS mutation may be a predictor of oxaliplatin sensitivity in CRC. KRAS was knocked-down in KRAS-mutant CRC cells (DLD-1^G13D and SW480^G12V) by small interfering RNAs (siRNA) and overexpressed in KRAS-wild-type CRC cells (COLO320DM) by KRAS-mutant vectors to generate paired CRC cells. These paired CRC cells were tested by oxaliplatin, irinotecan and 5FU to determine the change in drug sensitivity by MTT assay and flow cytometry. Reasons for sensitivity alteration were further determined by western blot and real-time quantitative reverse transcriptase polymerase chain reaction (qRT -PCR). In KRAS-wild-type CRC cells (COLO320DM), KRAS overexpression by mutant vectors caused excision repair cross-complementation group 1 (ERCC1) downregulation in protein and mRNA levels, and enhanced oxaliplatin sensitivity. In contrast, in KRAS-mutant CRC cells (DLD-1^G13D and SW480^G12V), KRAS knocked-down by KRAS-siRNA led to ERCC1 upregulation and increased oxaliplatin resistance. The sensitivity of irinotecan and 5FU had not changed in the paired CRC cells. To validate ERCC1 as a predictor of sensitivity for oxaliplatin, ERCC1 was knocked-down by siRNA in KRAS-wild-type CRC cells, which restored oxaliplatin sensitivity. In contrast, ERCC1 was overexpressed by ERCC1-expressing vectors in KRAS-mutant CRC cells, and caused oxaliplatin resistance. Overall, our findings suggest that KRAS mutation is a predictor of oxaliplatin sensitivity in colon cancer cells by the mechanism of ERCC1 downregulation.

Abstract B52: Design and synthesis of GADD45β agonists for sorefenib-resistance hepatocellular carcinoma cells

Background: Growth arrest DNA damage-inducible gene 45β (GADD45β) have been reported in regulating cellular stress response, survival, senescence, and apoptosis in cancer cells. Our previous data showed that GADD45β was induced in sorafenib-treated hepatocellular carcinoma (HCC) cell line and xenograft models. Sorafenib induction was not induced after the treatment ERK kinase inhibitor (U1206) and Raf inhibitor (ZM336372), suggesting that Raf/MEK/ERK kinase signaling pathway did not involve in induction of GADD45β by sorafenib.

Methods: We have designed and synthesized a series of SC-compounds. These compounds were treated with and analyzed in terms of GADD45β expression in HCC cell lines (Huh-7, Huh7R). Also, Effects of SC-compounds and sorafenib induced cell apoptosis were evaluated.

Results: In seeking new GADD45β agonists, we have screened a series of compounds with GADD45β expression assay. SC-20, a small molecule with N-(4-(quinolin-4-yloxy)phenyl)benzamide skeleton, has shown significantly in induction of GADD45β expression. Interestingly, SC-20 has no inhibition in phosphorylation of ERK, indicating that GADD45β induction by SC-20 is independent of ERK signaling pathway. In addition, SC-20 is able to inhibit HCC cell growth with MTT assay and further induce cell apoptosis. Moreover, SC-20 is able to overcome sorafenib resistance cell line by activating GADD45β expression.

Conclusions: SC-20 provides a new concept that increasing GADD45β along will be applicable in sorafenib-sensitive and resistant HCC therapy.

Grant support: NSC-100-2325-B-002-042, DOH100-TD-B-111-001, NSC-100-2325-B-010-007

IκB kinases increase Myc protein stability and enhance progression of breast cancer cells

BACKGROUND

Both IκB kinase (IKK) complex and oncgenic protein Myc play important roles in cancer progression, including cancer cell invasiveness and metastasis. The levels of Myc is regulated by the phosphorylation of Myc at Thr58 and Ser62.

RESULTS

In this study, we show that the expression of Myc is associated with IKKα and IKKβ in breast cancers and that Myc is an IKKs substrate. Suppression of IKK activity by either chemical inhibitor or transfection of kinase-dead mutants decreases the phosphorylation of Myc at Ser62 and enhances the degradation of Myc. Consequently, these treatments decrease the tumorigenic and invasive ability of breast cancer cells. Furthermore, doxorubicin, a frequently used anticancer drug in breast cancer, activates IKKs and Myc, thereby increasing invasiveness and tumorigenesis of breast carcinoma MCF7 cells. Inhibition of IKKs prevents these doxorubicin-induced effects.

CONCLUSIONS

Our study indicates that IKKs tightly regulate Myc expression through prolonging protein stability, and suggests that IKKs are potentially therapeutic targets and that suppression of IKKs may be used following chemotherapy to reduce the risk of treatment-induced tumor progression.

Abstract B226: Induction of growth arrest DNA damage-inducible gene 45 beta (GADD45b) expression contributes to sorafenib-induced apoptosis in hepatocellular carcinoma (HCC) cells

GADD45b, which is associated with cellular stress response and apoptosis regulation, was frequently under-expressed in HCC. In a previous study we found GADD45b belongs to a group of sorafenib-regulated genes that are independent of mitogen-activated protein kinase-extracellular signal-regulated kinase (MEK)/ extracellular signal-regulated kinase (ERK) signaling pathway. The present study explored the role of sorafenib-induced GADD45b expression in HCC cells. HCC cell lines tested included HepG2, Hep3B, Huh-7, and Huh-7R, a sorafenib-resistant cell line established by continuously exposure of Huh-7 cells to sorafenib. GADD45b expression was examined by quantitative real-time PCR and western blotting. Control of GADD45b transcription was examined by luciferase reporter assay using a series of reporter plasmids with deletions or site-directed mutants of the 5′-flanking region of GADD45b promoter. Apoptosis was analyzed by measuring the subG1 fraction and annexin V staining using flow cytometry. Both the mRNA and the protein levels of GADD45b was increased after sorafenib but not after the MEK inhibitor CI-1040 or U0126 treatment, suggesting that GADD45b induction was independent of cellular MEK/ERK activity. GADD45b induction was more prominent in sorafenib-sensitive HCC cells (Huh-7 and HepG2, IC50 6–7 µM) but less so prominent in sorafenib-resistant HCC cells (Hep3B and Huh-7R, IC50 12–15 µM). Knockdown of GADD45b expression by siRNA partially abrogated the pro-apoptotic effects of sorafenib in Huh-7 and HepG2 cells but not Hep3B cells. The region −339/−267 in the 5′-flanking region of GADD45b promoter, which contained AP-1 (−298/−292) and Sp1 (−285/−277) binding sites, was found crucial for GADD45b induction by sorafenib. Binding of c-Jun and Sp1 to GADD45b promoter was confirmed by chromatin immunoprecipitation. Sorafenib also increased the phosphorylation of JNK in sorafenib-sensitive but not in sorafenib-resistant HCC cells. Sorafenib-induced GADD45b expression can be alleviated by treatment with the specific JNK inhibitor SP600125. Our data indicated that induction of GADD45b expression, which is mediated by cellular JNK/c-Jun signaling pathway but not MEK/ERK signaling, contributes to sorafenib-induced apoptosis in HCC cells. Failure of GADD45b induction may confer sorafenib resistance. GADD45b may be used as a predictive biomarker for sorafenib sensitivity in HCC. (Supported by grants NSC97-3112-B-002-012, NSC98-3112-B-002-007, NSC98-3112-B-002-037)

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B226.

Abstract A241: Searching for extracellular signal-regulated kinase (ERK)-independent molecular targets of sorafenib in hepatocellular carcinoma (HCC)

We have recently identified Bim, a pro-apoptotic factor regulated by ERK signaling pathway, is an important mediator of sorafenib-induced apoptosis in HCC cells.. In this study we further explored other possible mediators of sorafenib activity in HCC cells that is independent of mitogen-activated protein kinase-extracellular signal-regulated kinase (MEK)/ERK signaling. Huh7 cells were treated with sorafenib or the MEK inhibitor CI-1040, alone or in combination, for 24 hours. The gene expression profiles were analyzed by Affymetrix oligonucleotide microarray analysis using HG_U133A chip, and the candidate genes were selected if (1) they had &gt; 1.2 fold or &lt; 0.8 fold change than control after treatment with sorafenib 10 M and (2) they had been reported to be involved in important carcinogenesis-related cellular signaling pathways, such as apoptosis regulation, cell proliferation/survival, cell cycle control, and angiogenesis. The gene expression was considered MEK/ERK-dependent if the direction of changes was similar after treatment with sorafenib 10 M or CI-1040 1 M; otherwise it was considered MEK/ERK-independent. Thirty candidate genes of interest were identified and the expression patterns were validated by real-time PCR (see table). The 14 genes whose expressions were considered ERK-independent involved apoptosis regulation (GADD45b, BAX, JUN), cell proliferation (PCNA, RPS6KA3, SMAD7, BMP2, DUSP1, DUSP8, IL1RAP, RHEB), cell cycle control (CCNE1, CDC25A), and angiogenesis (VEGF). Validation of the biological significance of these markers is ongoing. The preliminary data revealed that induction of GADD45b and JUN gene expression after sorafenib treatment was correlated with intrinsic or acquired resistance of HCC cells to sorafenib. Our data indicated that MEK/ERK-independent signaling pathways may also contribute to sorafenib-induced apoptosis and growth regulation in HCC cells. The signaling molecules identified in this study can serve as novel therapeutic targets for HCC. (Supported by grants NSC97-3112-B-002-012, NSC98-3112-B-002-007, NSC98-3112-B-002-037)

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A241.

Abstract B97: Dichloroacetate (DCA) enhances activities of sorafenib against hepatocellular carcinoma (HCC) via modulation of aberrant cellular metabolism of HCC cells

To meet high energy demand for proliferation, cancer cells rely more on aerobic glycolysis than on oxidative phosphorylation (OXPHOS). This aberrant cellular metabolism of cancer, well-known as the “Warburg effect”, may confer survival advantages and drug resistance to cancer cells. Pyruvate dehydrogenase (PDH) is the gatekeeper of OXPHOS, and is inhibited by pyruvate dehyrogenase kinase (PDK) through phosphorylation. Dichloroacetate (DCA), a synthetic PDK inhibitor, can reverse glycosis to OXPHOS through PDH activation, and has been used for the treatment of congenital lactic acidosis for more than 30 years. The present study explored whether modulating the Warburg effect by DCA can improve the efficacy of sorafenib (a multi-kinase inhibitor of Raf, VEGFR and PDGFR), the current standard systemic therapy for HCC. Modulation of the Warburg effect was evaluated by measurement of lactate in culture medium and PDH activity. In vitro growth-inhibitory effects were measured by median-effect analyses in a panel of human HCC cell-lines (Hep3B, Huh-7, Sk-hep1, HCC36 and HA22T) cultured in normoxic condition. In vivo growth-inhibitory effects were measured in both subcutaneous and orthotopic murine HCC xenograft models. Apoptosis was evaluated by flow cytometry (annexin V staining and subG1 fraction analysis) and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Expression of apoptosis-related proteins was analyzed by Western blotting. We found that DCA reduced lactate production and increased PDH activity in HCC cells in a dose-dependent manner, indicating switching glucose metabolism from glycolysis to OXPHOS. DCA (10–60 mM) induced synergistic growth-inhibitory and apoptotic effects with sorafenib in most HCC cell-lines tested. Nude mice carrying subcutaneously or intrahepatically implanted Hep3B cells were treated with vehicle, DCA 100 mg/kg /day (equivalent to the dosage used to treat lactic acidosis in human), sorafenib 10 mg/kg /day, and DCA plus sorafenib, via gavage for 21 days. DCA-sorafenib combination synergistically suppressed the tumor growth without advertently affecting the body weight of mice. Synergistic induction of apoptosis was shown by TUNEL assay. Our data suggest that modulation of aberrant cellular metabolism of HCC cells by DCA may improve the clinical efficacy of sorafenib. (Supported by grants NSC97-3112-B-002-012, NSC98-3112-B-002-007, and NSC98-3112-B-002-037)

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B97.

Induction of Bim expression contributes to the antitumor synergy between sorafenib and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibitor CI-1040 in hepatocellular carcinoma

PURPOSE

Sorafenib has proved survival benefit for patients with advanced hepatocellular carcinoma (HCC). This study explored whether the efficacy of sorafenib can be improved by adding the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor CI-1040 to vertically block the Raf/MEK/ERK pathway.

EXPERIMENTAL DESIGN

The growth inhibitory effects of sorafenib and CI-1040 were tested in HCC cell lines (Huh-7 and Hep3B) and human umbilical vascular endothelial cells (HUVEC). The potential synergistic growth inhibitory effects were measured by median effect analysis. Apoptosis was measured by flow cytometry. The effects on ERK phosphorylation and levels of apoptosis regulatory proteins were measured by Western blotting. The in vivo antitumor activity of sorafenib and CI-1040 were tested in xenograft HCC models.

RESULTS

Combination of sorafenib and CI-1040 synergistically inhibited ERK phosphorylation and cell growth and induced apoptosis in both HCC cells and HUVECs. Increased expression of Bim protein, which correlated with the extent of ERK inhibition, was found in both HCC cells and HUVECs. Knockdown of Bim expression by small interfering RNA partially abrogated the synergistic proapoptotic effects of sorafenib and CI-1040. Combination therapy inhibited tumor growth significantly better than either single agent in the xenograft models.

CONCLUSION

The antitumor effects of sorafenib in HCC can be improved by vertical blockade of Raf/MEK/ERK signaling with CI-1040.

Role of Twist in head and neck carcinoma with lymph node metastasis

The transcription factor Twist protein has been found to be correlated with metastasis in various carcinomas, including hepatocellular, breast and prostate carcinomas. However, the role of Twist in head and neck squamous cell carcinomas (HNSCC) remains unknown. Head and neck cancer tissue microarrays (TMAs) of tumors from 50 patients with HNSCC were examined. Immunohistochemical (IHC) stain analysis showed that, out of the 50 patients, twenty (40%) showed Twist-positive staining in the tumor cells, and Twist expression was positively associated with differentiation status (p=0.027), lymph node metastasis (p=0.032) and disease progression (p=0.029). Further analysis revealed that the expression of Twist was positively correlated with CXCR4 (Spearman, r=0.408, p=0.003) and CCR7 (r=0.417, p=0.003). FindPatterns analysis suggested that the transcription factor Twist, as a basic helix-loop-helix (bHLH) protein, might regulate CXCR4 and CCR7 expression in squamous cell carcinomas, which in turn might be associated with lymph node metastasis.

Expression of syndecan-1 (CD138) in nasopharyngeal carcinoma is correlated with advanced stage and poor prognosis

Nasopharyngeal carcinoma (NPC) is an important Epstein-Barr virus-associated head and neck malignancy in Taiwan. Syndecan-1 (CD138) is involved in growth, differentiation, invasiveness, and metastatic potential of certain tumors, but its expression in NPC has never been studied. In this study, detection of expression of syndecan-1 protein and Epstein-Barr virus-encoded latent membrane protein-1 (LMP-1) in primary, recurrent, and metastatic NPC specimens in paraffin sections was performed by immunohistochemistry. The quantity of syndecan-1 messenger RNA in tumor cells was investigated by real-time reverse transcriptase polymerase chain reaction using laser capture microdissection. The results of immunohistochemical staining of syndecan-1 and LMP-1 correlated with clinicopathologic features of NPC. Eighteen (20.9%) of 86 primary, 9 (24.3%) of 37 recurrent, and 15 (44.1%) of 34 metastatic NPC samples were positive for syndecan-1, and 37 (43.0%) primary, 18 (48.6%) recurrent, and 12 (35.3%) metastatic samples were positive for LMP-1 expression. Primary NPCs with syndecan-1 protein expression were more frequently associated with advanced clinical stages and worse 5-year survival rates than those without (P = .015 and P = .0021, respectively). Conversely, the LMP-1 expression did not correlate with tumor stage or prognosis but occurred more often in nonkeratinizing carcinoma than keratinizing squamous cell carcinoma (unpublished observation). The inverse expression of syndecan-1 and LMP-1 was noted in primary NPC specimens (total 4/18 versus 35/68, P = .05). The reverse transcriptase polymerase chain reaction revealed low syndecan-1 messenger RNA levels in both primary and metastatic NPC. In conclusion, the protein expression of syndecan-1 in 21% of primary NPC was associated with advanced disease and poor prognosis, and the protein expression correlated with transcription levels.