Abstract New studies indicate that the side population (SP) and cancer stem cells (CSC) drive and maintain many types of human malignancies. SP and CSC appear to be highly resistant to chemo- and ...radio-therapy and this knowledge is now reshaping our therapeutic approach to cancer. Several studies have pioneered the possibility of specifically targeting CSC and SP cells by exploiting pathways involved in drug resistance, or forcing these cells to proliferate and differentiate thus converting them into a target of conventional therapies. Moreover, certain cytokines – such as IFN-α – appear to modulate SP and stem cell functions, and this associates with remarkable therapeutic activity in animal models. These recent findings underscore the need of a more comprehensive view of the interactions between cytokines and key regulatory pathways in SP and CSC.
Cholangiocarcinoma (CCA) is characterized by an abundant stromal reaction. Cancer‐associated fibroblasts (CAFs) are pivotal in tumor growth and invasiveness and represent a potential therapeutic ...target. To understand the mechanisms leading to CAF recruitment in CCA, we studied (1) expression of epithelial‐mesenchymal transition (EMT) in surgical CCA specimens and CCA cells, (2) lineage tracking of an enhanced green fluorescent protein (EGFP)‐expressing human male CCA cell line (EGI‐1) after xenotransplantation into severe‐combined‐immunodeficient mice, (3) expression of platelet‐derived growth factors (PDGFs) and their receptors in vivo and in vitro, (4) secretion of PDGFs by CCA cells, (5) the role of PDGF‐D in fibroblast recruitment in vitro, and (6) downstream effectors of PDGF‐D signaling. CCA cells expressed several EMT biomarkers, but not alpha smooth muscle actin (α‐SMA). Xenotransplanted CCA masses were surrounded and infiltrated by α‐SMA‐expressing CAFs, which were negative for EGFP and the human Y‐probe, but positive for the murine Y‐probe. CCA cells were strongly immunoreactive for PDGF‐A and ‐D, whereas CAFs expressed PDGF receptor (PDGFR)β. PDGF‐D, a PDGFRβ agonist, was exclusively secreted by cultured CCA cells. Fibroblast migration was potently induced by PDGF‐D and CCA conditioned medium and was significantly inhibited by PDGFRβ blockade with Imatinib and by silencing PDGF‐D expression in CCA cells. In fibroblasts, PDGF‐D activated the Rac1 and Cdc42 Rho GTPases and c‐Jun N‐terminal kinase (JNK). Selective inhibition of Rho GTPases (particularly Rac1) and of JNK strongly reduced PDGF‐D‐induced fibroblast migration. Conclusion: CCA cells express several mesenchymal markers, but do not transdifferentiate into CAFs. Instead, CCA cells recruit CAFs by secreting PDGF‐D, which stimulates fibroblast migration through PDGFRβ and Rho GTPase and JNK activation. Targeting tumor or stroma interactions with inhibitors of the PDGF‐D pathway may offer a novel therapeutic approach. (Hepatology 2013;53:1042–1053)
Classification of variants in the BRCA1 and BRCA2 genes has a major impact on the clinical management of subjects at high risk for breast and ovarian cancer. The identification of a pathogenic ...variant allows for early detection/prevention strategies in healthy carriers as well as targeted treatments in patients affected by BRCA-associated tumors. The BRCA2 c.9227G>T p.(Gly3076Val) variant recurs in families from Northeast Italy and is rarely reported in international databases. This variant substitutes the evolutionary invariant glycine 3076 with a valine in the DNA binding domain of the BRCA2 protein, thus suggesting a high probability of pathogenicity. We analysed clinical and genealogic data of carriers from 15 breast/ovarian cancer families in whom no other pathogenic variants were detected. The variant was shown to co-segregate with breast and ovarian cancer in the most informative families. Combined segregation data led to a likelihood ratio of 81,527:1 of pathogenicity vs. neutrality. We conclude that c.9227G>T is a BRCA2 pathogenic variant that recurs in Northeast Italy. It can now be safely used for the predictive testing of healthy family members to guide preventive surgery and/or early tumor detection strategies, as well as for PARP inhibitors treatments in patients with BRCA2-associated tumors.
Cholangiocarcinoma (CCA) carries a severe prognosis because of its strong invasiveness and early metastasization. In several patients, otherwise eligible for surgical resection, micrometastasis are ...already present at the time of surgery. The mechanisms responsible for CCA invasiveness are unclear. S100A4, a member of the S100 family of small Ca2+‐binding proteins, is expressed in mesenchymal cells, regulates cell motility in several cell types, and is expressed in some epithelial cancers. Thus, we aimed to study the role of S100A4 in CCA invasiveness and metastasization. The expression of S100A4 was studied by immunohistochemistry in 93 human liver samples of CCA patients undergoing surgical resection and correlated with metastases development (67 cases) and patient survival following surgery using log rank tests and multivariate analysis. S100A4 expression was studied in EGI‐1 and TFK‐1, human CCA cell lines with and without nuclear S100A4 expression, respectively. Metastatic properties of CCA cells were assessed by xenotransplantation in severe combined immunodeficiency (SCID) mice after transduction with lentiviral vectors encoding firefly luciferase gene. Proliferation, motility (wound healing), invasiveness (Boyden chamber), and metalloproteinases (MMPs) secretion were studied in CCA cells, with or without lentiviral silencing of S100A4. Nuclear expression of S100A4 by neoplastic ducts was a strong predictor of metastasization and reduced survival after resection (P < 0.01). EGI‐1 CCA cells showed stronger metastatic properties than TFK‐1 when xenotransplanted in SCID mice. S100A4‐silenced EGI‐1 cells showed significantly reduced motility, invasiveness, and MMP‐9 secretion in vitro, without changes in cell proliferation. Conclusion: Nuclear S100A4 identifies a subset of CCA patients with a poor prognosis after surgical resection. Nuclear expression of S100A4 increases CCA cells invasiveness and metastasization, indicating that S100A4 may also represent a potential therapeutic target. (HEPATOLOGY 2011; 54:890–899)
VEGF antagonists are now widely used cancer therapeutics, but predictive biomarkers of response or toxicity remain unavailable. In this study, we analyzed the effects of anti-VEGF therapy on tumor ...metabolism and therapeutic response by using an integrated set of imaging techniques, including bioluminescence metabolic imaging, 18-fluorodeoxyglucose positron emission tomography, and MRI imaging and spectroscopy. Our results revealed that anti-VEGF therapy caused a dramatic depletion of glucose and an exhaustion of ATP levels in tumors, although glucose uptake was maintained. These metabolic changes selectively accompanied the presence of large necrotic areas and partial tumor regression in highly glycolytic tumors. In addition, we found that the central metabolic protein kinase AMP-activated protein kinase (AMPK)-a cellular sensor of ATP levels that supports cell viability in response to energy stress-was activated by anti-VEGF therapy in experimental tumors. AMPK-α2 attenuation increased glucose consumption, tumor cell sensitivity to glucose starvation, and tumor necrosis following anti-VEGF therapy. Taken together, our findings reveal functional links between the Warburg effect and the AMPK pathway with therapeutic responses to VEGF neutralization in tumor xenograft models.
An open debate in antiangiogenic therapies is about their consequence on tumor invasiveness and metastasis, which is undoubtedly relevant for patients currently treated with antiangiogenics, such as ...renal cell carcinoma patients. To address, this we developed an extensive series of 27 patient biopsy‐derived orthotopic xenograft models (Ren‐PDOX) that represent inter‐patient heterogeneity. In specific tumors, antiangiogenics produced increased invasiveness and metastatic dissemination, while in others aggressiveness remained unchanged. Mechanistically, species‐discriminative RNA sequencing identified a tumor cell‐specific differential expression profile associated with tumor progression and aggressivity in TCGA RCC patients. Gene filtering using an invasion‐annotated patient series pinpointed two candidate genes, of which ALDH1A3 differentiated the pro‐invasive subtype of Ren‐PDOXs. Validation in an independent series of 15 antiangiogenic‐treated patients confirmed that pre‐treatment ALDH1A3 can significantly discriminate patients with pro‐aggressive response upon treatment. Overall, results confirm that effects of antiangiogenic drugs on tumor invasion and metastasis are heterogeneous and may profoundly affect the natural progression of tumors and promote malignancy. Furthermore, we identify a specific molecular biomarker that could be used to select patients that better benefit from treatment.
Renal cell carcinoma (RCC) biopsy‐derived orthotopic xenograft models (PDOX) reveal patient‐specific induction of invasion and metastasis after antiangiogenics. Molecular characterization identifies ALDH1A3 as a pre‐treatment discriminator of pro‐malignant tumors that predicts response to therapy.
Patient's original histomorphologic and molecular characteristics were maintained in an extensive series of 27 patient biopsy‐derived orthotopic xenograft models (Ren‐PDOX).
Antiangiogenic treatment produced patient‐specific responses of increased invasiveness and metastatic dissemination in approximately half of the models studied.
By a novel technique of species‐discriminative RNA‐sequencing and subsequent filtering using patient data, the key molecular traits of pro‐invasive type of tumors was unraveled.
ALDH1A3 was clinically validated as a possible predictive factor of pro‐aggressiveness in 15 antiangiogenic‐treated RCC patients.
Renal cell carcinoma (RCC) biopsy‐derived orthotopic xenograft models (PDOX) reveal patient‐specific induction of invasion and metastasis after antiangiogenics. Molecular characterization identifies ALDH1A3 as a pre‐treatment discriminator of pro‐malignant tumors that predicts response to therapy.
Tumor growth requires induction of an angiogenic program, and targeting of this program with antiangiogenic drugs shows an impact on tumor progression. However, although they are effective at ...reducing angiogenesis, these therapies have not produced widespread or enduring clinical benefit, which openly exposes their limitations. Here, we describe the current limitations of these therapies, including the known mechanisms and current controversies. Further, we present some of the recent approaches to predict these limitations and strategies to overcome them. With the development of meaningful predictive biomarkers and effective treatments that impede these limitations, longer and more robust efficacies will be achieved for a wider population of patients.
Bone marrow mesenchymal stromal cells (BM-MSCs) may survive and proliferate in the presence of cycling neoplastic cells. Exogenously administered MSCs are actively incorporated in the tumor as ...stromal fibroblasts, thus competing with the local mesenchymal cell precursors. For this reason, MSCs have been suggested as a suitable carrier for gene therapy strategies, as they can be genetically engineered with genes encoding for biologically active molecules that can inhibit tumor cell proliferation and enhance the antitumor immune response. We used BM-MSCs engineered with the murine interferon-alpha (IFN-α) gene (BM-MSCs/IFN-α) to assess in a mouse plasmacytoma model the efficacy of this approach toward neoplastic plasma cells. We found that IFN-α can be efficiently produced and delivered inside the tumor microenvironment. Subcutaneous multiple administration of BM-MSCs/IFN-α significantly hampered the tumor growth in vivo and prolonged the overall survival of mice. The antitumor effect was associated with enhanced apoptosis of tumor cells, reduction in microvessel density, and ischemic necrosis. By contrast, intravenous administration of BM-MSCs/IFN-α did not significantly modify the survival of mice, mainly as a consequence of an excessive entrapment of injected cells in the pulmonary vessels. In conclusion, BM-MSCs/IFN-α are effective in inhibiting neoplastic plasma cell growth; however, systemic administration of engineered MSCs needs to be improved to make this approach potentially suitable for the treatment of multiple myeloma.
The multifactorial likelihood analysis method has demonstrated utility for quantitative assessment of variant pathogenicity for multiple cancer syndrome genes. Independent data types currently ...incorporated in the model for assessing BRCA1 and BRCA2 variants include clinically calibrated prior probability of pathogenicity based on variant location and bioinformatic prediction of variant effect, co‐segregation, family cancer history profile, co‐occurrence with a pathogenic variant in the same gene, breast tumor pathology, and case‐control information. Research and clinical data for multifactorial likelihood analysis were collated for 1,395 BRCA1/2 predominantly intronic and missense variants, enabling classification based on posterior probability of pathogenicity for 734 variants: 447 variants were classified as (likely) benign, and 94 as (likely) pathogenic; and 248 classifications were new or considerably altered relative to ClinVar submissions. Classifications were compared with information not yet included in the likelihood model, and evidence strengths aligned to those recommended for ACMG/AMP classification codes. Altered mRNA splicing or function relative to known nonpathogenic variant controls were moderately to strongly predictive of variant pathogenicity. Variant absence in population datasets provided supporting evidence for variant pathogenicity. These findings have direct relevance for BRCA1 and BRCA2 variant evaluation, and justify the need for gene‐specific calibration of evidence types used for variant classification.
...SEMAs can positively or negatively modulate many intrinsic properties of tumour cells, such as proliferation, cell survival, alteration in cell adhesion and tumour invasiveness, but also modulate ...several stromal components including endothelial cell migration and survival (Capparuccia & Tamagnone, 2009; Serini et al, 2009). In tumour cells, on the contrary, ErbB2 plays a master role in the pro‐invasive, pro‐metastatic properties of p61‐Sema3E with PlxnD1 forming a complex with ErbB2 that results in its transactivation and further activation of EGFR‐ErbB2‐mediated signalling pathways (Casazza et al, 2010; Fig 1A). ...the well‐documented negative effect on endothelial cells exerted by Sema3E makes it a good candidate to block angiogenesis in tumours. ...results from Casazza et al demonstrate Uncl‐Sema3E anti‐tumour activity is maintained in models refractory to VEGF therapy. ...efforts have to be made to define the anti‐cancer outcome of combinatorial Uncl‐Sema3E together with standard anti‐angiogenic therapy to determine whether there could be additive anti‐angiogenic effects and compensatory anti‐invasive and anti‐metastatic effects.
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