Cabozantinib plus atezolizumab versus sorafenib for advanced hepatocellular carcinoma (COSMIC-312): a multicentre, open-label, randomised, phase 3 trial.

BACKGROUND: Cabozantinib has shown clinical activity in combination with checkpoint inhibitors in solid tumours. The COSMIC-312 trial assessed cabozantinib plus atezolizumab versus sorafenib as first-line systemic treatment for advanced hepatocellular carcinoma. METHODS: COSMIC-312 is an open-label, randomised, phase 3 trial that enrolled patients aged 18 years or older with advanced hepatocellular carcinoma not amenable to curative or locoregional therapy and previously untreated with systemic anticancer therapy at 178 centres in 32 countries. Patients with fibrolamellar carcinoma, sarcomatoid hepatocellular carcinoma, or combined hepatocellular cholangiocarcinoma were not eligible. Tumours involving major blood vessels, including the main portal vein, were permitted. Patients were required to have measurable disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), Barcelona Clinic Liver Cancer stage B or C disease, an Eastern Cooperative Oncology Group performance status of 0 or 1, adequate organ and marrow function, and Child-Pugh class A. Previous resection, tumour ablation, radiotherapy, or arterial chemotherapy was allowed if more than 28 days before randomisation. Patients were randomly assigned (2:1:1) via a web-based interactive response system to cabozantinib 40 mg orally once daily plus atezolizumab 1200 mg intravenously every 3 weeks, sorafenib 400 mg orally twice daily, or single-agent cabozantinib 60 mg orally once daily. Randomisation was stratified by disease aetiology, geographical region, and presence of extrahepatic disease or macrovascular invasion. Dual primary endpoints were progression-free survival per RECIST 1.1 as assessed by a blinded independent radiology committee in the first 372 patients randomly assigned to the combination treatment of cabozantinib plus atezolizumab or sorafenib (progression-free survival intention-to-treat [ITT] population), and overall survival in all patients randomly assigned to cabozantinib plus atezolizumab or sorafenib (ITT population). Final progression-free survival and concurrent interim overall survival analyses are presented. This trial is registered with ClinicalTrials.gov, NCT03755791. FINDINGS: Analyses at data cut-off (March 8, 2021) included the first 837 patients randomly assigned between Dec 7, 2018, and Aug 27, 2020, to combination treatment of cabozantinib plus atezolizumab (n=432), sorafenib (n=217), or single-agent cabozantinib (n=188). Median follow-up was 15·8 months (IQR 14·5-17·2) in the progression-free survival ITT population and 13·3 months (10·5-16·0) in the ITT population. Median progression-free survival was 6·8 months (99% CI 5·6-8·3) in the combination treatment group versus 4·2 months (2·8-7·0) in the sorafenib group (hazard ratio [HR] 0·63, 99% CI 0·44-0·91, p=0·0012). Median overall survival (interim analysis) was 15·4 months (96% CI 13·7-17·7) in the combination treatment group versus 15·5 months (12·1-not estimable) in the sorafenib group (HR 0·90, 96% CI 0·69-1·18; p=0·44). The most common grade 3 or 4 adverse events were alanine aminotransferase increase (38 [9%] of 429 patients in the combination treatment group vs six [3%] of 207 in the sorafenib group vs 12 [6%] of 188 in the single-agent cabozantinib group), hypertension (37 [9%] vs 17 [8%] vs 23 [12%]), aspartate aminotransferase increase (37 [9%] vs eight [4%] vs 18 [10%]), and palmar-plantar erythrodysaesthesia (35 [8%] vs 17 [8%] vs 16 [9%]); serious treatment-related adverse events occurred in 78 (18%) patients in the combination treatment group, 16 (8%) patients in the sorafenib group, and 24 (13%) in the single-agent cabozantinib group. Treatment-related grade 5 events occurred in six (1%) patients in the combination treatment group (encephalopathy, hepatic failure, drug-induced liver injury, oesophageal varices haemorrhage, multiple organ dysfunction syndrome, and tumour lysis syndrome), one (<1%) patient in the sorafenib group (general physical health deterioration), and one (<1%) patient in the single-agent cabozantinib group (gastrointestinal haemorrhage). INTERPRETATION: Cabozantinib plus atezolizumab might be a treatment option for select patients with advanced hepatocellular carcinoma, but additional studies are needed. FUNDING: Exelixis and Ipsen.

Efficacy and safety of cabozantinib for patients with advanced hepatocellular carcinoma based on albumin-bilirubin grade.

BACKGROUND: Albumin-bilirubin (ALBI) grade is an objective measure of liver function for patients with hepatocellular carcinoma (HCC). The tyrosine kinase inhibitor cabozantinib is approved for patients with advanced HCC who have received prior sorafenib based on the phase 3 CELESTIAL trial (NCT01908426). Cabozantinib improved overall survival (OS) and progression-free survival (PFS) versus placebo in patients with previously treated HCC. METHODS: Patients were randomised 2:1 to receive cabozantinib 60 mg or placebo orally every day. Clinical outcomes in patients with ALBI grade 1 or 2 at baseline were evaluated in CELESTIAL. ALBI scores were retrospectively calculated based on baseline serum albumin and total bilirubin, with an ALBI grade of 1 defined as ≤ -2.60 score and a grade of 2 as a score of > -2.60 to ≤ -1.39. RESULTS: Cabozantinib improved OS and PFS versus placebo in both ALBI grade 1 (hazard ratio [HR] [95% CI]: 0.63 [0.46-0.86] and 0.42 [0.32-0.56]) and ALBI grade 2 (HR [95% CI]: 0.84 [0.66-1.06] and 0.46 [0.37-0.58]) subgroups. Adverse events were consistent with those in the overall population. Rates of grade 3/4 adverse events associated with hepatic decompensation were generally low and were more common among patients in the ALBI grade 2 subgroup. DISCUSSION: These results provide initial support of cabozantinib in patients with advanced HCC irrespective of ALBI grade 1 or 2. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov number, NCT01908426.

AI-supported modified risk staging for multiple myeloma cancer useful in real-world scenario.

INTRODUCTION: An efficient readily employable risk prognostication method is desirable for MM in settings where genomics tests cannot be performed owing to geographical/economical constraints. In this work, a new Modified Risk Staging (MRS) has been proposed for newly diagnosed Multiple Myeloma (NDMM) that exploits six easy-to-acquire clinical parameters i.e. age, albumin, ß2-microglobulin (ß2M), calcium, estimated glomerular filtration rate (eGFR) and hemoglobin. MATERIALS AND METHODS: MRS was designed using a training cohort of 716 NDMM patients of our inhouse MM Indian (MMIn) cohort and validated on MMIn (n=354) cohort and MMRF (n=900) cohort. K-adaptive partitioning (KAP) was used to find new thresholds for the parameters. Risk staging rules, obtained via training a J48 classifier, were used to build MRS. RESULTS: New thresholds were identified for albumin (3.6 g/dL), ß2M (4.8 mg/L), calcium (11.13 mg/dL), eGFR (48.1 mL/min), and hemoglobin (12.3 g/dL) using KAP on the MMIn dataset. On the MMIn dataset, MRS outperformed ISS for OS prediction in terms of C-index, hazard ratios, and its corresponding p-values, but performs comparable in prediction of PFS. On both MMIn and MMRF datasets, MRS performed better than RISS in terms of C-index and p-values. A simple online tool was also designed to allow automated calculation of MRS based on the values of the parameters. DISCUSSION: Our proposed ML-derived yet simple staging system, MRS, although does not employ genetic features, outperforms RISS as confirmed by better separability in KM survival curves and higher values of C-index on both MMIn and MMRF datasets. FUNDING: Grant: BT/MED/30/SP11006/2015 (Department of Biotechnology, Govt. of India), Grant: DST/ICPS/CPS-Individual/2018/279(G) (Department of Science and Technology, Govt. of India), UGC-Senior Research Fellowship.

Cabozantinib in combination with atezolizumab versus sorafenib in treatment-naive advanced hepatocellular carcinoma: COSMIC-312 Phase III study design.

Cabozantinib is an oral tyrosine kinase inhibitor that targets VEGFR, MET and the TAM (TYRO3, AXL, MER) family of kinase receptors. In addition to their role in tumor growth and angiogenesis, cabozantinib targets promote an immune-suppressive microenvironment. Cabozantinib is approved as single-agent therapy for patients with advanced hepatocellular carcinoma who received prior sorafenib. Owing to its antitumor and immunomodulatory properties, cabozantinib is being developed in combination with immune checkpoint inhibitors. Early studies of these combinations have shown promising antitumor activity and tolerability in patients with solid tumors. Here, we describe the rationale and design of COSMIC-312, a Phase III study evaluating the safety and efficacy of cabozantinib in combination with atezolizumab (anti-PD-L1 monoclonal antibody) versus sorafenib for treatment-naive patients with advanced hepatocellular carcinoma. ClinicalTrial.gov Registration: NCT03755791.

Loss of miR125a expression in a model of K-ras-dependent pulmonary premalignancy.

Understanding the molecular pathogenesis of lung cancer is necessary to identify biomarkers/targets specific to individual airway molecular profiles and to identify options for targeted chemoprevention. Herein, we identify mechanisms by which loss of microRNA (miRNA)125a-3p (miR125a) contributes to the malignant potential of human bronchial epithelial cells (HBEC) harboring an activating point mutation of the K-ras proto-oncogene (HBEC K-ras). Among other miRNAs, we identified significant miR125a loss in HBEC K-ras lines and determined that miR125a is regulated by the PEA3 transcription factor. PEA3 is upregulated in HBEC K-ras cells, and genetic knockdown of PEA3 restores miR125a expression. From a panel of inflammatory/angiogenic factors, we identified increased CXCL1 and vascular endothelial growth factor (VEGF) production by HBEC K-ras cells and determined that miR125a overexpression significantly reduces K-ras-mediated production of these tumorigenic factors. miR125a overexpression also abrogates increased proliferation of HBEC K-ras cells and suppresses anchorage-independent growth (AIG) of HBEC K-ras/P53 cells, the latter of which is CXCL1-dependent. Finally, pioglitazone increases levels of miR125a in HBEC K-ras cells via PEA3 downregulation. In addition, pioglitazone and miR125a overexpression elicit similar phenotypic responses, including suppression of both proliferation and VEGF production. Our findings implicate miR125a loss in lung carcinogenesis and lay the groundwork for future studies to determine whether miR125a is a possible biomarker for lung carcinogenesis and/or a chemoprevention target. Moreover, our studies illustrate that pharmacologic augmentation of miR125a in K-ras-mutated pulmonary epithelium effectively abrogates several deleterious downstream events associated with the mutation.

Antagonism of EGFR and HER3 enhances the response to inhibitors of the PI3K-Akt pathway in triple-negative breast cancer.

Both abundant epidermal growth factor receptor (EGFR or ErbB1) and high activity of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway are common and therapeutically targeted in triple-negative breast cancer (TNBC). However, activation of another EGFR family member [human epidermal growth factor receptor 3 (HER3) (or ErbB3)] may limit the antitumor effects of these drugs. We found that TNBC cell lines cultured with the EGFR or HER3 ligand EGF or heregulin, respectively, and treated with either an Akt inhibitor (GDC-0068) or a PI3K inhibitor (GDC-0941) had increased abundance and phosphorylation of HER3. The phosphorylation of HER3 and EGFR in response to these treatments was reduced by the addition of a dual EGFR and HER3 inhibitor (MEHD7945A). MEHD7945A also decreased the phosphorylation (and activation) of EGFR and HER3 and the phosphorylation of downstream targets that occurred in response to the combination of EGFR ligands and PI3K-Akt pathway inhibitors. In culture, inhibition of the PI3K-Akt pathway combined with either MEHD7945A or knockdown of HER3 decreased cell proliferation compared with inhibition of the PI3K-Akt pathway alone. Combining either GDC-0068 or GDC-0941 with MEHD7945A inhibited the growth of xenografts derived from TNBC cell lines or from TNBC patient tumors, and this combination treatment was also more effective than combining either GDC-0068 or GDC-0941 with cetuximab, an EGFR-targeted antibody. After therapy with EGFR-targeted antibodies, some patients had residual tumors with increased HER3 abundance and EGFR/HER3 dimerization (an activating interaction). Thus, we propose that concomitant blockade of EGFR, HER3, and the PI3K-Akt pathway in TNBC should be investigated in the clinical setting.

mTORC1 inhibition is required for sensitivity to PI3K p110α inhibitors in PIK3CA-mutant breast cancer.

Activating mutations of the PIK3CA gene occur frequently in breast cancer, and inhibitors that are specific for phosphatidylinositol 3-kinase (PI3K) p110α, such as BYL719, are being investigated in clinical trials. In a search for correlates of sensitivity to p110α inhibition among PIK3CA-mutant breast cancer cell lines, we observed that sensitivity to BYL719 (as assessed by cell proliferation) was associated with full inhibition of signaling through the TORC1 pathway. Conversely, cancer cells that were resistant to BYL719 had persistently active mTORC1 signaling, although Akt phosphorylation was inhibited. Similarly, in patients, pS6 (residues 240/4) expression (a marker of mTORC1 signaling) was associated with tumor response to BYL719, and mTORC1 was found to be reactivated in tumors from patients whose disease progressed after treatment. In PIK3CA-mutant cancer cell lines with persistent mTORC1 signaling despite PI3K p110α blockade (that is, resistance), the addition of the allosteric mTORC1 inhibitor RAD001 to the cells along with BYL719 resulted in reversal of resistance in vitro and in vivo. Finally, we found that growth factors such as insulin-like growth factor 1 and neuregulin 1 can activate mammalian target of rapamycin (mTOR) and mediate resistance to BYL719. Our findings suggest that simultaneous administration of mTORC1 inhibitors may enhance the clinical activity of p110α-targeted drugs and delay the appearance of resistance.

PGE(2) contributes to TGF-beta induced T regulatory cell function in human non-small cell lung cancer.

CD4(+)CD25(bright) regulatory T cells (T(reg)) play an important role in cancer-mediated immunosuppression. We and others have previously shown that prostaglandin E2 (PGE(2)) and transforming growth factor beta (TGF-beta) induce CD4(+)CD25(bright)FOXP3(+)T(reg). Based on these studies, we investigated the requirement for PGE(2) in Treg induction by TGF-beta. TGF-beta stimulation of human CD4(+) T cells induced COX-2-dependent production of PGE(2). PGE(2)-neutralizing antibody treatment significantly reduced the suppressive function of TGF-beta-induced T(reg) (TGF-beta-T(reg)) in vitro. TGF-beta concentration measured in the plasma of non-small cell lung cancer (NSCLC) patients directly correlated with the frequency of circulating CD4(+)CD25(bright)FOXP3(+)T cells. Flow cytometry analysis showed increased FOXP3 expression in circulating CD4(+)CD25(+)HLA-DR- cells of lung cancer patients compared to control subjects. Immunohistochemical analysis revealed co-expression of TGF-beta, COX-2, and FOXP3 in serial sections from resected lung tumor tissues. All together these observations suggest interplay between TGF-beta and COX-2 in the induction of T(reg) activities. Interrupting TGF-beta and PGE(2) signaling may be important in therapeutic interventions that aim to limit T(reg)function in lung cancer.

Proinflammatory mediators upregulate snail in head and neck squamous cell carcinoma.

PURPOSE: Inflammatory cytokines have been implicated in the progression of head and neck squamous cell carcinoma (HNSCC). Herein we investigate the mechanisms by which interleukin-1beta (IL-1beta) might contribute to Epithelial-Mesenchymal Transition (EMT) in HNSCC. EXPERIMENTAL DESIGN: We evaluated the effect of IL-1beta on the molecular events of EMT in surgical specimens and HNSCC cell lines. We examined the correlation with tumor histologic features, and a SCID xenograft model was used to assess the effects of Snail overexpression. RESULTS: Cyclooxygenase-2 (COX-2)-dependent pathways contribute to the modulation of E-cadherin expression in HNSCC. An inverse relationship between COX-2 and E-cadherin was shown in situ by double immunohistochemical staining of human HNSCC tissue sections. Treatment of HNSCC cells with IL-1beta caused the downregulation of E-cadherin expression and upregulation of COX-2 expression. This effect was blocked in the presence of COX-2 small hairpin RNA. IL-1beta-treated HNSCC cell lines showed a significant decrease in E-cadherin mRNA and an increase in the mRNA expression of the transcriptional repressor Snail. IL-1beta exposure led to enhanced Snail binding at the chromatin level. Small hairpin RNA-mediated knockdown of Snail interrupted the capacity of IL-1beta to downregulate E-cadherin. In a SCID xenograft model, HNSCC Snail-overexpressing cells showed significantly increased primary and metastatic tumor burdens. CONCLUSIONS: IL-1beta modulates Snail and thereby regulates COX-2-dependent E-cadherin expression in HNSCC. This is the first report indicating the role of Snail in the inflammation-induced promotion of EMT in HNSCC. This newly defined pathway for transcriptional regulation of E-cadherin in HNSCC has important implications for targeted chemoprevention and therapy.

The Role of PPARgamma in the Cyclooxygenase Pathway in Lung Cancer.

Decreased expression of peroxisome proliferator activated receptor-gamma (PPARgamma) and high levels of the proinflammatory enzyme cyclooxygenase-2 (COX-2) have been observed in many tumor types. Both reduced (PPARgamma) expression and elevated COX-2 within the tumor are associated with poor prognosis in lung cancer patients, and recent work has indicated that these signaling pathways may be interrelated. Synthetic (PPARgamma) agonists such as the thiazolidinedione (TZD) class of anti-diabetic drugs can decrease COX-2 levels, inhibit growth of non-small-cell lung cancer (NSCLC) cells in vitro, and block tumor progression in xenograft models. TZDs alter the expression of COX-2 and consequent production of the protumorigenic inflammatory molecule prostaglandin E2 (PGE2) through both (PPARgamma) dependent and independent mechanisms. Certain TZDs also reduce expression of PGE2 receptors or upregulate the PGE2 catabolic enzyme 15-prostaglandin dehydrogenase. As several COX-2 enzymatic products have antitumor properties and specific COX-2 inhibition has been associated with increased risk of adverse cardiac events, directly reducing the effects or concentration of PGE2 may provide a more safe and effective strategy for lung cancer treatment. Understanding the mechanisms underlying these effects may be helpful for designing anticancer therapies. This article summarizes recent research on the relationship between (PPARgamma), TZDs, and the COX-2/PGE2 pathways in lung cancer.

Pre-clinical characterization of GMP grade CCL21-gene modified dendritic cells for application in a phase I trial in non-small cell lung cancer.

BACKGROUND: Our previous studies have demonstrated that transduction of human dendritic cells (DC) with adenovirus encoding secondary lymphoid chemokine, CCL21, led to secretion of biologically active CCL21 without altering DC phenotype or viability. In addition, intratumoral injections of CCL21-transduced DC into established murine lung tumors resulted in complete regression and protective anti-tumor immunity. These results have provided the rationale to generate a clinical grade adenoviral vector encoding CCL-21 for ex vivo transduction of human DC in order to assess intratumoral administration in late stage human lung cancer. METHODS: In the current study, human monocyte-derived DC were differentiated by exposure to GM-CSF and IL-4 from cryopreserved mononuclear cells obtained from healthy volunteers. Transduction with clinical grade adenoviral vector encoding CCL21 (1167 viral particles per cell) resulted in secretion of CCL21 protein. RESULTS: CCL21 protein production from transduced DC was detected in supernatants (24-72 hours, 3.5-6.7 ng/4-5 x 10(6) cells). DC transduced with the clinical grade adenoviral vector were > 88% viable (n = 16), conserved their phenotype and maintained integral biological activities including dextran uptake, production of immunostimulatory cytokines/chemokines and antigen presentation. Furthermore, supernatant from CCL21-DC induced the chemotaxis of T2 cells in vitro. CONCLUSION: Viable and biologically active clinical grade CCL21 gene-modified DC can be generated from cryopreserved PBMC.

Fat paradox of steatohepatitis.

Alcoholic and non-alcoholic steatohepatitis (ASH and NASH) constitute two major types of chronic liver disease with worldwide prevalence and are histologically indistinguishable with shared pathogenetic mechanisms. More importantly, they have synergistic interactions for liver pathology. Comparative studies on ASH and NASH have been hampered by the use of different animal models with confounding variables, particularly those with extreme genetic, toxic, and malnutrition etiologies. The mouse intragastric model circumvents these problems and reproduces the natural course and etiological background of ASH and NASH. Further, our recent work reproduces a profound synergism between the two in the model. Intracellular accumulation of neural lipids is a hallmark biochemical feature of ASH and NASH. Although impaired lipid oxidation and export may contribute to this pathological change, enhanced lipogenic regulation is frequently encountered, as characterized by induction of lipogenic or adipogenic transcription factors (peroxisome proliferator-activated receptor [PPAR gamma], liver X receptor alpha[LXR alpha], sterol-regulatory element-binding protein-1c [SREBP-1c]). In contrast, we have recently defined transdifferentiation of hepatic stellate cells (HSC), a pivotal event in liver fibrogenesis, as an 'antilipogenic' or 'anti-adipogenic' phenomenon. Thus, there is an apparent paradox between hepatocytes and HSC in steatohepatitis in terms of the outcome of lipogenic regulation. Our recent work suggests that defective insulin signaling in activated HSC may be responsible for this paradox. Further, activated Wnt signaling is implicated in 'anti-adipogenic' stellate cell transdifferentiation in liver fibrogenesis.

Inflammation and lung carcinogenesis: applying findings in prevention and treatment.

Lung carcinogenesis is a complex process requiring the acquisition of genetic mutations that confer the malignant phenotype as well as epigenetic alterations that may be manipulated in the course of therapy. Inflammatory signals in the lung cancer microenvironment can promote apoptosis resistance, proliferation, invasion, metastasis, and secretion of proangiogenic and immunosuppressive factors. Here, we discuss several prototypical inflammatory mediators controlling the malignant phenotype in lung cancer. Investigation into the detailed molecular mechanisms underlying the tumor-promoting effects of inflammation in lung cancer has revealed novel potential drug targets. Cytokines, growth factors and small-molecule inflammatory mediators released in the developing tumor microenvironment pave the way for epithelial-mesenchymal transition, the shift from a polarized, epithelial phenotype to a highly motile mesenchymal phenotype that becomes dysregulated during tumor invasion. Inflammatory mediators within the tumor microenvironment are derived from neoplastic cells as well as stromal and inflammatory cells; thus, lung cancer develops in a host environment in which the deregulated inflammatory response promotes tumor progression. Inflammation-related metabolic and catabolic enzymes (prostaglandin E(2) synthase, prostaglandin I(2) synthase and 15-hydroxyprostaglandin dehydrogenase), cell-surface receptors (E-type prostaglandin receptors) and transcription factors (ZEB1, SNAIL, PPARs, STATs and NF-kappaB) are differentially expressed in lung cancer cells compared with normal lung epithelial cells and, thus, may contribute to tumor initiation and progression. These newly discovered molecular mechanisms in the pathogenesis of lung cancer provide novel opportunities for targeted therapy and prevention in lung cancer.

Ciglitazone mediates COX-2 dependent suppression of PGE2 in human non-small cell lung cancer cells.

BACKGROUND: Cyclooxygenase-2 (COX-2) over-expression and subsequent prostaglandin E2 (PGE2) production are frequently associated with human non-small-cell lung cancer (NSCLC) and are involved in tumor proliferation, invasion, angiogenesis, and resistance to apoptosis. Here, we report that ciglitazone downregulates PGE2 in NSCLC cells. METHODS: PGE2 ELISA assay and COX-2 ELISA assay were performed for measuring PGE2 and COX-2, respectively, in NSCLC. The mRNA level of COX-2 was measured by semi-quantitative RT-PCR. The transient transfection experiments were performed to measure COX-2 and peroxisome proliferator-response element (PPRE) promoter activity in NSCLC. Western blots were unitized to measure PGE synthase (PGES) and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) protein expression. RESULTS: COX-2 ELISA assays suggested that ciglitazone-dependent inhibition of PGE2 occurs through the suppression of COX-2. Ciglitazone treatment suppressed COX-2 mRNA expression and COX-2 promoter activity while upregulating PPRE promoter activity. Ciglitazone did not modify the expression of enzymes downstream of COX-2 including PGES and 15-PGDH. Utilization of a dominant-negative PPARgamma showed that the suppression of COX-2 and PGE2 by ciglitazone is mediated via non-PPAR pathways. CONCLUSION: Taken together, our findings suggest that ciglitazone is a negative modulator of COX-2/PGE2 in NSCLC.

Pioglitazone and rosiglitazone decrease prostaglandin E2 in non-small-cell lung cancer cells by up-regulating 15-hydroxyprostaglandin dehydrogenase.

Lung cancer cells elaborate the immunosuppressive and antiapoptotic mediator prostaglandin E(2) (PGE(2)), a product of cyclooxygenase-2 (COX-2) enzyme activity. Because peroxisome proliferator-activated receptor (PPAR)gamma ligands, such as thiazolidinediones (TZDs), inhibit lung cancer cell growth, we examined the effect of the TZDs pioglitazone and rosiglitazone on PGE(2) levels in non-small-cell lung cancer (NSCLC) A427 and A549 cells. Both TZDs inhibited PGE(2) production in NSCLC cells via a COX-2 independent pathway. To define the mechanism underlying COX-2 independent suppression of PGE(2) production, we focused on other enzymes responsible for the synthesis and degradation of PGE(2). The expression of none of the three prostaglandin synthases (microsomal PGES1, PGES2 and cystosolic PGES) was down-regulated by the TZDs. It is noteworthy that 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme that produces biologically inactive 15-ketoprostaglandins from active PGE(2), was induced by TZDs. The TZD-mediated suppression of PGE(2) concentration was significantly inhibited by small interfering RNA to 15-PGDH. Studies using dominant-negative PPARgamma overexpression or 2-chloro-5-nitrobenzanilide (GW9662; a PPARgamma antagonist) revealed that the suppressive effect of the TZDs on PGE(2) is PPARgamma-independent. Together, these findings indicate that it is possible to use a clinically available pharmacological intervention to suppress tumor-derived PGE(2) by enhancing catabolism rather than blocking synthesis.

Anti-adipogenic regulation underlies hepatic stellate cell transdifferentiation.

Cirrhosis is the most important consequence of alcoholic liver disease for which liver transplantation is the only treatment option available. Transdifferentiation of hepatic stellate cells (HSC) to myofibroblastic cells (MF) is a central event in liver fibrogenesis, and understanding molecular mechanisms that underlie this cellular event provides pivotal insights into development of new therapeutic modalities for cirrhosis. To this end, the authors proposed several years ago that transdifferentiation of quiescent HSC to MF may be causally associated with transcriptional regulation known for adipocyte-preadipocytic fibroblast dedifferentiation. In support of this notion, the authors showed that adipogenic transcription factors and their downstream adipocyte specific genes are expressed abundantly in quiescent HSC and that this expression profile is lost in HM. Further, gain-of-function manipulations for adipogenic transcription factors such as peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and sterol regulatory element binding protein-1c have been shown to reverse culture-induced MF to quiescent HSC. The authors also demonstrated that tumor necrosis factor-alpha and Wnt, known mediators of anti-adipogenesis, also suppress the activity of PPAR-gamma and contribute to HSC-MF transdifferentiation. These results reinforce the concept of adipogenic regulation essential to the quiescent phenotype and the loss of such regulation underlying HSC-HM transdifferentiation. They also provide insights into the molecular basis for the use of PPAR-gamma agonists, which has been advocated for treatment of liver fibrosis.

Chemoprevention strategies with cyclooxygenase-2 inhibitors for lung cancer.

Clinical lung cancer is the ultimate event resulting from a series of genetic and epigenetic alterations in the respiratory epithelium at risk. According to the "field carcinogenesis" theory, these alterations can occur throughout the entire lung. In individuals with a genetic predisposition combined with a sufficient amount of procarcinogenic environmental influences, a few of these sites may eventually progress to malignancies. Recent advances in the understanding of tumor biology have identified new therapeutic targets for lung cancer chemoprevention, among which is cyclooxgygenase (COX)-2. Ample preclinical data suggest that the COX-2/prostaglandin E2 (PGE2) signaling pathway plays a pivotal role in conferring the malignant phenotype. Produced primarily by the action of COX on the free arachidonic acid liberated from membrane phospholipids, overproduction of PGE2, which is predominantly generated by upregulation of COX-2, is associated with a variety of mechanisms known to facilitate tumorigenesis. These mechanisms include abnormal expression of epithelial growth factors, epithelial and microvascular proliferation, resistance to apoptosis, and suppression of antitumor immunity. The lung is one of the major sites of PGE2 production, and previous studies have shown elevated PGE2 levels in bronchoalveolar lavage fluid of patients with bronchogenic carcinoma. In animal models, inhibition of COX-2 and PGE2 synthesis suppresses lung tumorigenesis. These preclinical data suggesting the antineoplastic effect of COX-2 inhibitors provide the basis for several ongoing pilot clinical trials to determine the feasibility of COX-2 inhibition in chemoprevention of bronchogenic carcinoma.

Adipogenic transcriptional regulation of hepatic stellate cells.

Hepatic stellate cells (HSC) undergo transdifferentiation (activation) from lipid-storing pericytes to myofibroblastic cells to participate in liver fibrogenesis. Our recent work demonstrates that depletion of peroxisome proliferator-activated receptor gamma (PPARgamma) constitutes one of the key molecular events for HSC activation and that ectopic expression of this nuclear receptor achieves the phenotypic reversal of activated HSC to the quiescent cells. The present study extends these findings to test a novel hypothesis that adipogenic transcriptional regulation is required for the maintenance of HSC quiescence. Comparative analysis of quiescent and activated HSC in culture reveals higher expression of putative adipogenic transcription factors such as CCAAT/enhancer-binding protein (C/EBP) alpha, C/EBPbeta, C/EBPdelta, PPARgamma, liver X receptor alpha, sterol regulatory element-binding protein 1c and of adipocyte-specific genes in the quiescent cells. Conversely, activated HSC have increased expression of PPARbeta, a transcription factor known to promote fatty acid oxidation. A treatment of activated HSC with the adipocyte differentiation mixture (isobutylmethylxanthine, dexamethasone, and insulin) or ectopic expression of PPARgamma or SREBP-1c in these cells, induces a panel of adipogenic transcription factors, reduces PPARbeta, and causes the phenotypic reversal to quiescent HSC. These results support the importance of adipogenic transcriptional regulation in HSC quiescence and provide a new framework for identifying novel molecular targets for the treatment of liver cirrhosis.

PPAR Gamma and Hepatic Stellate Cells.

Activation of Hepatic stellate cells (HSC) in fibrogenesis involves distinct morphological and biochemical changes. This activation requires the coordinated changes in activity of several transcription factors. Peroxisome proliferator-activated receptor gamma (PPAR gamma) is one such factor whose activity is decreased in activated HSC. PPAR gamma ligands suppress several markers of HSC activation such as expression of collagen and alpha smooth muscle actin (alpha-SMA), cell proliferation and migration. Expression of PPAR gamma, per se, also inhibits HSC activation. These findings support the role of PPAR gamma in reversion of activated HSC toward their quiescent state.