Project for interventional Oncology LArge-database in liveR Hepatocellular carcinoma - Preliminary CT-based radiomic analysis (POLAR Liver 1.1).

OBJECTIVE: The objective of this study is to find a contrast-enhanced CT-radiomic signature to predict clinical incomplete response in patients affected by hepatocellular carcinoma who underwent locoregional treatments. PATIENTS AND METHODS: 190 patients affected by hepatocellular carcinoma treated using focal therapies (radiofrequency or microwave ablation) from September 2018 to October 2020 were retrospectively enrolled. Treatment response was evaluated on a per-target-nodule basis on the 6-months follow-up contrast-enhanced CT or MR imaging using the mRECIST criteria. Radiomics analysis was performed using an in-house developed open-source R library. Wilcoxon-Mann-Whitney test was applied for univariate analysis; features with a p-value lower than 0.05 were selected. Pearson correlation was applied to discard highly correlated features (cut-off=0.9). The remaining features were included in a logistic regression model and receiver operating characteristic curves; sensitivity, specificity, positive and negative predictive value were also computed. The model was validated performing 2000 bootstrap resampling. RESULTS: 56 treated lesions from 42 patients were selected. Treatment responses were: complete response for 26 lesions (46.4%), 18 partial responses (32.1%), 10 stable diseases (17.9%), 2 progression diseases (3.6%). Area-Under-Curve value was 0.667 (95% CI: 0.527-0.806); accuracy, sensitivity, specificity, positive and negative predictive values were respectively 0.66, 0.85, 0.50, 0.59 and 0.79. CONCLUSIONS: This contrast-enhanced CT-based model can be helpful to early identify poor responder's hepatocellular carcinoma patients and personalize treatments.

In-depth characterization of a new patient-derived xenograft model for metaplastic breast carcinoma to identify viable biologic targets and patterns of matrix evolution within rare tumor types.

Metaplastic breast carcinoma (MBC) is a rare breast cancer subtype with rapid growth, high rates of metastasis, recurrence and drug resistance, and diverse molecular and histological heterogeneity. Patient-derived xenografts (PDXs) provide a translational tool and physiologically relevant system to evaluate tumor biology of rare subtypes. Here, we provide an in-depth comprehensive characterization of a new PDX model for MBC, TU-BcX-4IC. TU-BcX-4IC is a clinically aggressive tumor exhibiting rapid growth in vivo, spontaneous metastases, and elevated levels of cell-free DNA and circulating tumor cell DNA. Relative chemosensitivity of primary cells derived from TU-BcX-4IC was performed using the National Cancer Institute (NCI) oncology drug set, crystal violet staining, and cytotoxic live/dead immunofluorescence stains in adherent and organoid culture conditions. We employed novel spheroid/organoid incubation methods (Pu·MA system) to demonstrate that TU-BcX-4IC is resistant to paclitaxel. An innovative physiologically relevant system using human adipose tissue was used to evaluate presence of cancer stem cell-like populations ex vivo. Tissue decellularization, cryogenic-scanning electron microscopy imaging and rheometry revealed consistent matrix architecture and stiffness were consistent despite serial transplantation. Matrix-associated gene pathways were essentially unchanged with serial passages, as determined by qPCR and RNA sequencing, suggesting utility of decellularized PDXs for in vitro screens. We determined type V collagen to be present throughout all serial passage of TU-BcX-4IC tumor, suggesting it is required for tumor maintenance and is a potential viable target for MBC. In this study we introduce an innovative and translational model system to study cell-matrix interactions in rare cancer types using higher passage PDX tissue.

The diagnostic performance of PIVKA-II in metabolic and viral hepatocellular carcinoma: a pilot study.

OBJECTIVE: Hepatocellular carcinoma (HCC) is a primary liver tumor derived from metabolic or viral chronic hepatitis, with few treatment options in advanced cases. New biomarkers that allow improving diagnosis and staging are widely desired. Here, we aim to evaluate the performance of Protein Induced by Vitamin K Absence or Antagonist-II (PIVKA-II) in combination with α-fetoprotein (AFP), in the diagnosis of HCC in patients with metabolic or viral hepatitis. PATIENTS AND METHODS: We enrolled 60 HCC patients (20 metabolic and 40 viral) and 20 healthy subjects (HS) as negative controls. PIVKA-II, AFP, Matrix metalloproteinase-9 (MMP-9) and Fibroblast growth factor (FGF) serum levels were assessed by immunoassays. RESULTS: AFP and PIVKA-II levels were obviously higher in patients than in HS. AFP displayed a better diagnostic performance than PIVKA-II for viral HCC while PIVKA-II was better for metabolic HCC. The combination of the two biomarkers did not improve the discriminating ability. CONCLUSIONS: PIVKA-II may be considered an independent predictor of macrovascular invasion from HCC cells and it can be used to better stratify HCC patients and should be evaluated in prospective studies for early detection of advanced HCC in metabolic subjects.

SARS-CoV2 RNA detection in a pancreatic pseudocyst sample.

The involvement of gastrointestinal system in SARS-CoV2 related disease, COVID-19, is increasingly recognized. COVID-19 associated pancreatic injury has been suggested, but its correlation with pancreatic disease is still unclear. In this case report, we describe the detection of SARS-CoV2 RNA in a pancreatic pseudocyst fluid sample collected from a patient with SARS-CoV2 associated pneumonia and a pancreatic pseudocyst developed as a complication of an acute edematous pancreatitis. The detection of SARS-CoV2 within the pancreatic collection arise the question of whether this virus has a tropism for pancreatic tissue and whether it plays a role in pancreatic diseases occurrence.

IgG cryoglobulinemia.

OBJECTIVE: Mixed Cryoglobulinemia is the most well-known Hepatitis C Virus (HCV)-associated extrahepatic manifestation. MC is both an autoimmune and B-lymphoproliferative disorder. Cryoglobulins (CGs) are classified into three groups according to immunoglobulin (Ig) composition: type I is composed of one isotype or Ig class. Type II and type III mixed CGs are immune complexes composed of polyclonal IgGs acting as autoantigens and mono, polyclonal or oligoclonal IgM with rheumatoid factor activity. IgG1 and IgG3 are the predominant subclasses involved. This study shows the simultaneous presence of IgG-RF and IgG3, supporting the hypothesis of an involvement of this subclass in the initiation of early stages of CGs. PATIENTS AND METHODS: We describe a case series of six HCV-positive patients, all of whom had peripheral neuropathy and transient ischemic attacks, presenting cryoprecipitates formed by IgG3 and IgG1. Cryoprecipitate IgG subclass research was carried out by immunofixation electrophoresis by using antisera against IgG1, IgG2, IgG3, and IgG4. RESULTS: Our six patients presented with an immunochemical pattern characterized by the mere presence of IgG1 and IgG3 subclasses with probable RF activity and one of these six patients exhibited monoclonal IgG3 in his cerebrospinal fluid. CONCLUSIONS: We can hypothesize that the IgG passage through the blood-brain barrier could have contributed to the cause of TIAs, through a mechanism involving the precipitation of circulating immune complexes formed by the two subclasses in the intrathecal vessels.

Gut microbiome composition in lean patients with NASH is associated with liver damage independent of caloric intake: A prospective pilot study.

BACKGROUND AND AIM: The aim of the study was to compare the gut microbiomes from obese and lean patients with or without NASH to outline phenotypic differences. METHODS AND RESULTS: We performed a cross-sectional pilot study comprising biopsy-proven NASH patients grouped according to BMI. Microbiome DNA was extracted from stool samples, and PCR amplification was performed using primers for the V4 region of the 16S rRNA gene. The amplicons were sequenced using the Ion PGM Torrent platform, and data were analyzed using QIIME software. Macronutrient consumption was analyzed by a 7-day food record. Liver fibrosis ≥ F2 was associated with increased abundance of Lactobacilli (p = 0.0007). NASH patients showed differences in Faecalibacterium, Ruminococcus, Lactobacillus and Bifidobacterium abundance compared with the control group. Lean NASH patients had a 3-fold lower abundance of Faecalibacterium and Ruminococcus (p = 0.004), obese NASH patients were enriched in Lactobacilli (p = 0.002), and overweight NASH patients had reduced Bifidobacterium (p = 0.018). Moreover, lean NASH patients showed a deficiency in Lactobacillus compared with overweight and obese NASH patients. This group also appeared similar to the control group with regard to gut microbiome alpha diversity. Although there were qualitative differences between lean NASH and overweight/obese NASH, they were not statistically significant (p = 0.618). The study limitations included a small sample size, a food questionnaire that collected only qualitative and semi-quantitative data, and variations in group gender composition that may influence differences in FXR signaling, bile acids metabolism and the composition of gut microbiota. CONCLUSION: Our preliminary finding of a different pathogenetic process in lean NASH patients needs to be confirmed by larger studies, including those with patient populations stratified by sex and dietary habits.

Nonalcoholic fatty liver disease in patients with psoriasis: a consequence of systemic inflammatory burden?

Patients with psoriasis are at an increased risk for nonalcoholic fatty liver disease (NAFLD) compared with the general population. However, the pathophysiology underlying this comorbidity and elucidation of effective treatment strategies are unclear. This review provides insights into the possible role of chronic, low-grade inflammation in the pathogenesis of NAFLD in patients with psoriasis. Both conditions are associated with increased levels of proinflammatory adipokines (such as tumour necrosis factor-α and interleukin-6) and hepatokines, and decreased levels of adiponectin, an anti-inflammatory adipokine. This imbalance in inflammatory mediators could result in insulin resistance and, thereby, facilitate the occurrence and progression of NAFLD in a multistep manner. All patients with psoriasis should, therefore, be considered candidates for NAFLD screening and managed accordingly. Given the common aetiology of inflammation between these conditions, it is hypothesized that biological therapies for psoriasis may attenuate the systemic inflammatory process and progression of NAFLD in patients with psoriasis.

The Polycomb group (PcG) protein EZH2 supports the survival of PAX3-FOXO1 alveolar rhabdomyosarcoma by repressing FBXO32 (Atrogin1/MAFbx).

The Polycomb group (PcG) proteins regulate stem cell differentiation via the repression of gene transcription, and their deregulation has been widely implicated in cancer development. The PcG protein Enhancer of Zeste Homolog 2 (EZH2) works as a catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) by methylating lysine 27 on histone H3 (H3K27me3), a hallmark of PRC2-mediated gene repression. In skeletal muscle progenitors, EZH2 prevents an unscheduled differentiation by repressing muscle-specific gene expression and is downregulated during the course of differentiation. In rhabdomyosarcoma (RMS), a pediatric soft-tissue sarcoma thought to arise from myogenic precursors, EZH2 is abnormally expressed and its downregulation in vitro leads to muscle-like differentiation of RMS cells of the embryonal variant. However, the role of EZH2 in the clinically aggressive subgroup of alveolar RMS, characterized by the expression of PAX3-FOXO1 oncoprotein, remains unknown. We show here that EZH2 depletion in these cells leads to programmed cell death. Transcriptional derepression of F-box protein 32 (FBXO32) (Atrogin1/MAFbx), a gene associated with muscle homeostasis, was evidenced in PAX3-FOXO1 RMS cells silenced for EZH2. This phenomenon was associated with reduced EZH2 occupancy and H3K27me3 levels at the FBXO32 promoter. Simultaneous knockdown of FBXO32 and EZH2 in PAX3-FOXO1 RMS cells impaired the pro-apoptotic response, whereas the overexpression of FBXO32 facilitated programmed cell death in EZH2-depleted cells. Pharmacological inhibition of EZH2 by either 3-Deazaneplanocin A or a catalytic EZH2 inhibitor mirrored the phenotypic and molecular effects of EZH2 knockdown in vitro and prevented tumor growth in vivo. Collectively, these results indicate that EZH2 is a key factor in the proliferation and survival of PAX3-FOXO1 alveolar RMS cells working, at least in part, by repressing FBXO32. They also suggest that the reducing activity of EZH2 could represent a novel adjuvant strategy to eradicate high-risk PAX3-FOXO1 alveolar RMS.

Crosstalk between PKCα and Notch-4 in endocrine-resistant breast cancer cells.

The Notch pathway is functionally important in breast cancer. Notch-1 has been reported to maintain an estrogen-independent phenotype in estrogen receptor α (ERα)+ breast cancer cells. Notch-4 expression correlates with Ki67. Notch-4 also plays a key role in breast cancer stem-like cells. Estrogen-independent breast cancer cell lines have higher Notch activity than estrogen-dependent lines. Protein kinase Cα (PKCα) overexpression is common in endocrine-resistant breast cancers and promotes tamoxifen (TAM)-resistant growth in breast cancer cell lines. We tested whether PKCα overexpression affects Notch activity and whether Notch signaling contributes to endocrine resistance in PKCα-overexpressing breast cancer cells.Analysis of published microarray data from ERα+ breast carcinomas shows that PKCα expression correlates strongly with Notch-4. Real-time reverse transcription PCR and immunohistochemistry on archival specimens confirmed this finding. In a PKCα-overexpressing, TAM-resistant T47D model, PKCα selectively increases Notch-4, but not Notch-1, expression in vitro and in vivo. This effect is mediated by activator protein-1 (AP-1) occupancy of the Notch-4 promoter. Notch-4 knockdown inhibits estrogen-independent growth of PKCα-overexpressing T47D cells, whereas Notch-4IC expression stimulates it. Gene expression profiling shows that multiple genes and pathways associated with endocrine resistance are induced in Notch-4IC- and PKCα-expressing T47D cells. In PKCα-overexpressing T47D xenografts, an orally active γ-secretase inhibitor at clinically relevant doses significantly decreased estrogen-independent tumor growth, alone and in combination with TAM. In conclusion, PKCα overexpression induces Notch-4 through AP-1. Notch-4 promotes estrogen-independent, TAM-resistant growth and activates multiple pathways connected with endocrine resistance and chemoresistance. Notch inhibitors should be clinically evaluated in PKCα- and Notch-4-overexpressing, endocrine-resistant breast cancers.

Differentiating hepatocellular carcinoma from dysplastic nodules at gadobenate dimeglumine-enhanced hepatobiliary-phase magnetic resonance imaging.

PURPOSE: We evaluated whether the addition of delayed phase imaging (DPI) gadobenate dimeglumine-enhanced MRI to dynamic postcontrast imaging improves the characterization of small hepatocellular carcinoma (HCC) and the differentiation between HCC, high grade dysplastic nodules (HGDN), and low grade dysplastic nodules (LGDN). METHODS: Twenty-five cirrhotic patients with 30 nodules (16 HCC, 8 HGDNs, and 6 LGDNs; maximum size of 3 cm) were included in this retrospective study. The diagnostic reference standard was histology. All the patients underwent MRI both prior to and following intravenous administration of gadobenate dimeglumine. The lesions were classified as hypointense, isointense, hyperintense on DPI for qualitative assessment. In the quantitative analysis the relative tumor-liver contrast to noise ratio (CNR) of the lesions on DPI was calculated. RESULTS: All HCCs were hypointense on DPI while only 8 (57.1%) of 14 DNs were hypointense and only 1 of 6 (16.6%) LGDNs was hypointense. There was a statistically significant difference in the hypointensity on DPI between HCCs and DNs (p = 0.003) in the qualitative analysis but not in the CNR values while there was a strong statistically significant difference in the hypointensity on DPI in the qualitative (p = 0.00001) and quantitative analysis (p < 0.05) between LGDNs and the group obtained by unifying HGDNs and HCCs. CONCLUSION: DPI is helpful in differentiating HCCs and HGDNs from LGDNs. Demonstration of hypointensity on DPI should raise the suspicion of HGDN or hypovascular HCC in the case of nodules with atypical dynamic pattern.

Inhibition of Notch3 signalling induces rhabdomyosarcoma cell differentiation promoting p38 phosphorylation and p21(Cip1) expression and hampers tumour cell growth in vitro and in vivo.

Rhabdomyosarcoma (RMS) is a paediatric soft-tissue sarcoma arising from skeletal muscle precursors coexpressing markers of proliferation and differentiation. Inducers of myogenic differentiation suppress RMS tumourigenic phenotype. The Notch target gene HES1 is upregulated in RMS and prevents tumour cell differentiation in a Notch-dependent manner. However, Notch receptors regulating this phenomenon are unknown. In agreement with data in RMS primary tumours, we show here that the Notch3 receptor is overexpressed in RMS cell lines versus normal myoblasts. Notch3-targeted downregulation in RMS cells induces hyper-phosphorylation of p38 and Akt essential for myogenesis, resulting in the differentiation of tumour cells into multinucleated myotubes expressing Myosin Heavy Chain. These phenomena are associated to a marked decrease in HES1 expression, an increase in p21(Cip1) level and the accumulation of RMS cells in the G1 phase. HES1-forced overexpression in RMS cells reverses, at least in part, the pro-differentiative effects of Notch3 downregulation. Notch3 depletion also reduces the tumourigenic potential of RMS cells both in vitro and in vivo. These results indicate that downregulation of Notch3 is sufficient to force RMS cells into completing a correct full myogenic program providing evidence that it contributes, partially through HES1 sustained expression, to their malignant phenotype. Moreover, they suggest Notch3 as a novel potential target in human RMS.

Targeting both Notch and ErbB-2 signalling pathways is required for prevention of ErbB-2-positive breast tumour recurrence.

BACKGROUND: We reported that Notch-1, a potent breast oncogene, is activated in response to trastuzumab and contributes to trastuzumab resistance in vitro. We sought to determine the preclinical benefit of combining a Notch inhibitor (γ-secretase inhibitor (GSI)) and trastuzumab in both trastuzumab-sensitive and trastuzumab-resistant, ErbB-2-positive, BT474 breast tumours in vivo. We also studied if the combination therapy of lapatinib plus GSI can induce tumour regression of ErbB-2-positive breast cancer. METHODS: We generated orthotopic breast tumour xenografts from trastuzumab- or lapatinib-sensitive and trastuzumab-resistant BT474 cells. We investigated the antitumour activities of two distinct GSIs, LY 411 575 and MRK-003, in vivo. RESULTS: Our findings showed that combining trastuzumab plus a GSI completely prevented (MRK-003 GSI) or significantly reduced (LY 411 575 GSI) breast tumour recurrence post-trastuzumab treatment in sensitive tumours. Moreover, combining lapatinib plus MRK-003 GSI showed significant reduction of tumour growth. Furthermore, a GSI partially reversed trastuzumab resistance in resistant tumours. CONCLUSION: Our data suggest that a combined inhibition of Notch and ErbB-2 signalling pathways could decrease recurrence rates for ErbB-2-positive breast tumours and may be beneficial in the treatment of recurrent trastuzumab-resistant disease.

Transarterial chemoembolization (TACE) for unresectable HCC: a new life begins?

BACKGROUND AND OBJECTIVES: To provide an overview on the loco-regional therapy performed by transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC), either as sole, either as neoadjuvant to surgery or bridge therapy to orthotopic liver transplantation (OLT). EVIDENCE AND INFORMATION SOURCES: The current review is based on an analysis of the current literature and the caseload experience of the Authors on this topic. STATE OF THE ART: Chemoembolization combines de-arterialization of the tumor and selective delivery of chemotherapeutic agents into tumor's feeding vessels during angiography. Tumor ischemia raises the drug concentration compared to infusion alone and extends the retention of the chemotherapeutic drug. As locoregional therapy, TACE allows a complete local tumor control of 25-35% and permits an increase of survival in patients with intermediate HCC according to Barcelona-Clinic Liver Cancer (BCLC) classification. Excellent results were also achieved by combined therapies, such as with percutaneous ethanol injection or radiofrequency ablation, as neoadjuvant therapy prior to liver resection and in some circumstances as a bridging tool before liver transplantation. PERSPECTIVES: Drug eluting beads are microspheres that can be loaded with doxorubicin and induce toxic and ischemic necrosis with the same device; that allows an increase of drug selectively exposed to tumor cells and simultaneously a reduction of systemic toxicity. Tumor embolization induces a neoangiogenic reaction with a significant growth of adiacent satellites, so the association with sorafenib has a strong rationale for a combined therapy and is currently under investigation. CONCLUSIONS: Today TACE is the standard of care for treatment of intermediate hepatocellular carcinoma. To get the best performance it should be tailored according to the individual patient's condition.

Notch-1 stimulates survival of lung adenocarcinoma cells during hypoxia by activating the IGF-1R pathway.

Hypoxic microenvironment supports cancer stem cell survival, causes poor response to anticancer therapy and tumor recurrence. Inhibition of Notch-1 signaling in adenocarcinoma of the lung (ACL) cells causes apoptosis specifically under hypoxia. Here, we found that Akt-1 activation is a key mediator of Notch-1 pro-survival effects under hypoxia. Notch-1 activates Akt-1 through repression of phosphatase and tensin (PTEN) homolog expression and induction of the insulin-like growth factor 1 receptor (IGF-1R). The latter seems to be the major determinant of Akt-1 stimulation, as Notch-1 signaling affects Akt-1 activation in PTEN(-/-) ACL cells. Both downregulation of insulin receptor substrate 1 (IRS-1) and dominant-negative IGF-1R sensitized ACL cells to gamma-secretase inhibitor (GSI)-induced apoptosis. Conversely, overexpression of IGF-1R protected ACL cells from GSI toxicity. Inhibition of Notch-1 caused reduced IGF-1R expression, whereas forced Notch-1 expression yielded opposite effects. Chromatin immunoprecipitation experiments suggested Notch-1 direct regulation of the IGF-1R promoter. Experiments in which human ACL cells were injected in mice confirmed elevated and specific co-expression of Notch-1(IC), IGF-1R and pAkt-1 in hypoxic tumor areas. Our data provide a mechanistic explanation for Notch-1-mediated pro-survival function in hypoxic ACL tumor microenvironment. The results identify additional targets that may synergize with Notch-1 inhibition for ACL treatment.

Notch-1 activates estrogen receptor-alpha-dependent transcription via IKKalpha in breast cancer cells.

Approximately 80% of breast cancers express the estrogen receptor-alpha (ERalpha) and are treated with anti-estrogens. Resistance to these agents is a major cause of mortality. We have shown that estrogen inhibits Notch, whereas anti-estrogens or estrogen withdrawal activate Notch signaling. Combined inhibition of Notch and estrogen signaling has synergistic effects in ERalpha-positive breast cancer models. However, the mechanisms whereby Notch-1 promotes the growth of ERalpha-positive breast cancer cells are unknown. Here, we demonstrate that Notch-1 increases the transcription of ERalpha-responsive genes in the presence or absence of estrogen via a novel chromatin crosstalk mechanism. Our data support a model in which Notch-1 can activate the transcription of ERalpha-target genes via IKKalpha-dependent cooperative chromatin recruitment of Notch-CSL-MAML1 transcriptional complexes (NTC) and ERalpha, which promotes the recruitment of p300. CSL binding elements frequently occur in close proximity to estrogen-responsive elements (EREs) in the human and mouse genomes. Our observations suggest that a hitherto unknown Notch-1/ERalpha chromatin crosstalk mediates Notch signaling effects in ERalpha-positive breast cancer cells and contributes to regulate the transcriptional functions of ERalpha itself.

[The treatment of hepatocellular carcinoma: an update]. / Il trattamento dell'epatocarcinoma oggi.

Hepatocellular carcinoma (HCC) is the third most frequent cause of death from cancer with an increasing incidence in the world. Hepatic cirrhosis is the main risk factor for the development of this tumor, present in more than 80% of cases. The prognosis of this tumor is still poor and appears to be strictly related to liver residual function and tumor extension. A regular surveillance program was defined to increase early detection of tumor in cirrhotic patients when curative treatment could be applied. Liver transplantation and liver resection offer a high rate of positive response when applied in a early stage of the disease; locoregional therapies are effective, palliative options for patients with unresectable HCC: transarterial chemoembolisation being the only with a proven positive impact on survival. Several prognostic systems are proposed in the last years to stratify patients in different risk groups and to identify those who could achieve the best survival benefit from different therapeutic strategies: the Okuda system, the Cancer of the Liver Italian Program and the Barcelona Clínic Liver Cancer are the most widely used, but there is no consensus to which is the best in predicting outcome most accurately.

Rational targeting of Notch signaling in cancer.

Accumulating preclinical and clinical evidence supports a pro-oncogenic function for Notch signaling in several solid tumors, particularly but not exclusively in breast cancer. Notch inhibitory agents, such as gamma-secretase inhibitors, are being investigated as candidate cancer therapeutic agents. Interest in therapeutic modulation of the Notch pathway has been increased by recent reports, indicating that its role is important in controlling the fate of putative 'breast cancer stem cells'. However, as is the case for most targeted therapies, successful targeting of Notch signaling in cancer will require a considerable refinement of our understanding of the regulation of this pathway and its effects in both normal and cancer cells. Notch signaling has bidirectional 'cross talk' interaction with multiple other pathways that include candidate therapeutic targets. Understanding these interactions will greatly increase our ability to design rational combination regimens. To determine which patients are most likely to benefit from treatment with Notch inhibitors, it will be necessary to develop molecular tests to accurately measure pathway activity in specific tumors. Finally, mechanism-based toxicities will have to be addressed by a careful choice of therapeutic agents, combinations and regimens. This article summarizes the current state of the field, and briefly describes opportunities and challenges for Notch-targeted therapies in oncology.

Notch-1 associates with IKKalpha and regulates IKK activity in cervical cancer cells.

Notch-1 inhibits apoptosis in some transformed cells through incompletely understood mechanisms. Notch-1 can increase nuclear factor-kappa B (NF-kappaB) activity through a variety of mechanisms. Overexpression of cleaved Notch-1 in T-cell acute lymphoblastic leukemia cells activates NF-kappaB via interaction with the I kappa B kinase (IKK) signalosome. Concomitant activation of the Notch and NF-kappaB pathways has been described in a large series of cervical cancer specimens. Here, we show that wild-type, spontaneously expressed Notch-1 stimulates NF-kappaB activity in CaSki cervical cancer cells by associating with the IKK signalosome through IKKalpha. A significant fraction of tumor necrosis factor (TNF)-alpha-stimulated IkappaB kinase activity in CaSki cells is Notch-1-dependent. In addition, Notch-1 is found in the nucleus in association with IKKalpha at IKKalpha-stimulated promoters and is required for association of IKKalpha with these promoters under basal and TNF-alpha-stimulated conditions. Notch-1-IKKalpha complexes are found in normal human keratinocytes as well, suggesting that IKK regulation is a physiological function of Notch-1. Both Notch-1 and IKKalpha knockdown sensitize CaSki cells to cisplatin-induced apoptosis to equivalent extents. Our data indicate that Notch-1 regulates NF-kappaB in cervical cancer cells at least in part via cytoplasmic and nuclear IKK-mediated pathways.

ErbB-2 inhibition activates Notch-1 and sensitizes breast cancer cells to a gamma-secretase inhibitor.

ErbB-2 overexpression in breast tumors is associated with poor survival. Expression of Notch-1 and its ligand, Jagged-1, is associated with the poorest survival, including ErbB-2-positive tumors. Trastuzumab plus chemotherapy is the standard of care for ErbB-2-positive breast cancer. A proportion of tumors are initially resistant to trastuzumab and acquired resistance to trastuzumab occurs in metastatic breast cancer and is associated with poor prognosis. Thus, we investigated whether Notch-1 contributes to trastuzumab resistance. ErbB-2-positive cells have low Notch transcriptional activity compared to non-overexpressing cells. Trastuzumab or a dual epidermal growth factor receptor (EGFR)/ErbB-2 tyrosine kinase inhibitor (TKI) increased Notch activity by 2- to 6-fold in SKBr3, BT474 and MCF-7/HER2-18 cells. The increase in activity was abrogated by a Notch inhibitor, gamma-secretase inhibitor (GSI) or Notch-1 small-interfering RNA (siRNA). Trastuzumab decreased Notch-1trade mark precursor, increased amount and nuclear accumulation of active Notch-1(IC) and increased expression of targets, Hey1 and Deltex1 mRNAs, and Hes5, Hey1, Hes1 proteins. Importantly, trastuzumab-resistant BT474 cells treated with trastuzumab for 6 months expressed twofold higher Notch-1, twofold higher Hey1, ninefold higher Deltex1 mRNAs and threefold higher Notch-1 and Hes5 proteins, compared to trastuzumab-sensitive BT474 cells. The increase in Hey1 and Deltex1 mRNAs in resistant cells was abrogated by a Notch-1 siRNA. Cell proliferation was inhibited more effectively by trastuzumab or TKI plus a GSI than either agent alone. Decreased Notch-1 by siRNA increased efficacy of trastuzumab in BT474 sensitive cells and restored sensitivity in resistant cells. Trastuzumab plus a GSI increased apoptosis in sensitive cells by 20-30%. A GSI alone was sufficient to increase apoptosis in trastuzumab-resistant BT474 cells by 20%, which increased to 30% with trastuzumab. Notch-1 siRNA alone decreased cell growth by 30% in sensitive and more than 50% in resistant BT474 cells. Furthermore, growth of both trastuzumab sensitive and resistant cells was completely inhibited by combining trastuzumab plus Notch-1 siRNA. More importantly, Notch-1 siRNA or a GSI resensitized trastuzumab-resistant BT474 cells to trastuzumab. These results demonstrate that ErbB-2 overexpression suppresses Notch-1 activity, which can be reversed by trastuzumab or TKI. These results suggest that Notch-1 might play a novel role in resistance to trastuzumab, which could be prevented or reversed by inhibiting Notch-1.