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Insights into the molecular and cellular biology of embryonal rhabdomyosarcoma (ERMS), an aggressive paediatric tumour, are required in order to identify new targets for novel treatments that may benefit patients with this disease. The present study examined the functional effects of MKK3 and MKK6, two upstream kinases of p38, and found that the ectopic expression of MKK6 led to rapid p38 activation and the myogenic differentiation of ERMS cells, whereas MKK3 failed to induce differentiation, while maintaining the proliferation state. Myogenin and myosin heavy chain were induced in MKK6‑overexpressing ERMS cells and were inhibited by the p38 inhibitor, SB203580. The expression of Myc and ERK‑PO4 increased under the effect of SB203580, whereas it decreased in MKK6‑overexpressing cells. AKT activation was part of the myogenic program triggered by MKK6 overexpression alone. To the best of our knowledge, the present study demonstrates, for the first time, that the endogenous MKK6 pathway may be recovered by MEK/ERK inhibition (U0126 and trametinib) and that it concomitantly induces the reversal of the oncogenic pattern and the induction of the myogenic differentiation of ERMS cell lines. The effects of MEK/ERK inhibitors markedly increase the potential clinical applications in ERMS, particularly on account of the MEK inhibitor‑induced early MKK6/p38 axis activation and of their anti‑oncogenic effects. The findings presented herein lend further support to the antitumour effects of MKK6; MKK6 may thus represent a novel target for advanced personalised treatments against ERMS.

Persistence of drug-resistant quiescent leukemic stem cells (LSC) and impaired natural killer (NK) cell immune response account for relapse of chronic myelogenous leukemia (CML). Inactivation of protein phosphatase 2A (PP2A) is essential for CML-quiescent LSC survival and NK cell antitumor activity. Here we show that

Pharmacological treatment of colorectal carcinoma currently proceeds through the administration of a combination of different chemotherapeutic agents. In the case of rectal carcinoma, radiation therapy also represents a therapeutic strategy. In an attempt at translating much-needed new targeted therapy to the clinics, p38 mitogen activated protein kinase (MAPK) inhibitors have been tested in clinical trials involving colorectal carcinoma patients, especially in combination with chemotherapy; however, despite the high expectations raised by a clear involvement of the p38 MAPK pathway in the response to therapeutic treatments, poor results have been obtained so far. In this work, we review recent insights into the exact role of the p38 MAPK pathway in response to currently available therapies for colorectal carcinoma, depicting an intricate scenario in which the p38 MAPK node presents many opportunities, as well as many challenges, for its perspective exploitation for clinical purposes.

MKK3 is a member of the dual specificity kinase group specific upstream activator of p38 MAPK proteins. We originally identified MKK3 as mutant p53 (mutp53) gain-of-function (GOF) upregulated target gene in different tumor models. To deeply investigate the MKK3 functions in cancer, taking advantage of a panel of authenticated colorectal cancer (CRC) lines and primary colonocytes, we found that MKK3 activates specifically p38delta MAPK protein, which signaling is further triggered by 5-fluorouracil (5-FU) treatments, a largely adopted chemotherapeutic drug in CRC clinical practice. The overall achieved results proposed the MKK3/p38delta MAPK as relevant molecular axis involved in abrogating efficacy to 5-FU treatments in CRC. This commentary will provide an overall discussion of the results that have been achieved contextualizing them in the overview of the knowledge in the p38 MAPK field in cancer disease.

Colorectal cancer (CRC) is one of the most common malignant tumors worldwide and understanding its underlying molecular mechanisms is crucial for the development of therapeutic strategies. The mitogen-activated protein kinase-kinase 3 (MKK3) is a specific activator of p38 MAP kinases (p38 MAPKs), which contributes to the regulation of several cellular functions, such as proliferation, differentiation, apoptosis as well as response to drugs. At present, the exact MKK3/p38 MAPK pathway contribution in cancer is heavily debated because of its pleiotropic function. In this work, we retrospectively explored the prognostic and pathobiologic relevance of MKK3 in a cohort of CRC patients and assessed MKK3 molecular functions in a panel of CRC lines and colonocytes primary cultures. We found increased MKK3 levels in late-stage CRC patients which correlated with shorter overall survival. Herein, we report that the MKK3 targeting by inducible RNA interference univocally exerts antitumor effects in CRC lines but not in primary colonocytes. While MKK3 depletion per se affects growth and survival by induction of sustained autophagy and death in some CRC lines, it potentiates response to chemotherapeutic drug 5-fluorouracil (5-FU) in all of the tested CRC lines in vitro. Here, we demonstrate for the first time that in CRC the MKK3 specifically activates p38delta MAPK isoform to sustain prosurvival signaling and that such effect is exacerbated upon 5-FU challenge. Indeed, p38delta MAPK silencing recapitulates MKK3 depletion effects in CRC cells in vitro and in vivo. Overall, our data identified a molecular mechanism through which MKK3 supports proliferation and survival signaling in CRC, further supporting MKK3 as a novel and extremely attractive therapeutic target for the development of promising strategies for the management of CRC patients.

The use of imatinib, second and third generation ABL tyrosine kinase inhibitors (TKI) (i.e. dasatinib, nilotinib, bosutinib and ponatinib) made CML a clinically manageable and, in a small percentage of cases, a cured disease. TKI therapy also turned CML blastic transformation into a rare event; however, disease progression still occurs in those patients who are refractory, not compliant with TKI therapy or develop resistance to multiple TKIs. In the past few years, it became clear that the BCR-ABL1 oncogene does not operate alone to drive disease emergence, maintenance and progression. Indeed, it seems that bone marrow (BM) microenvironment-generated signals and cell autonomous BCR-ABL1 kinase-independent genetic and epigenetic alterations all contribute to: i. persistence of a quiescent leukemic stem cell (LSC) reservoir, ii. innate or acquired resistance to TKIs, and iii. progression into the fatal blast crisis stage. Herein, we review the intricate leukemic network in which aberrant, but finely tuned, survival, mitogenic and self-renewal signals are generated by leukemic progenitors, stromal cells, immune cells and metabolic microenvironmental conditions (e.g. hypoxia) to promote LSC maintenance and blastic transformation.

The docking protein p140Cap negatively regulates tumour cell features. Its relevance on breast cancer patient survival, as well as its ability to counteract relevant cancer signalling pathways, are not fully understood. Here we report that in patients with ERBB2-amplified breast cancer, a p140Cap-positive status associates with a significantly lower probability of developing a distant event, and a clear difference in survival. p140Cap dampens ERBB2-positive tumour cell progression, impairing tumour onset and growth in the NeuT mouse model, and counteracting epithelial mesenchymal transition, resulting in decreased metastasis formation. One major mechanism is the ability of p140Cap to interfere with ERBB2-dependent activation of Rac GTPase-controlled circuitries. Our findings point to a specific role of p140Cap in curbing the aggressiveness of ERBB2-amplified breast cancers and suggest that, due to its ability to impinge on specific molecular pathways, p140Cap may represent a predictive biomarker of response to targeted anti-ERBB2 therapies., p140Cap adaptor proteins interfere with adhesion and growth factor-dependent signalling in cancer cells but the mechanisms are unclear. Here the authors show that p140Cap interferes with ERBB2-dependent activation of Rac GTPase-controlled circuitries reducing metastasis and cancer progression.

In this issue of Blood, Agerstam et al1 and Zhang et al2 show that increased expression of the interleukin-1 receptor (IL-1R) complex confers leukemia stem cells (LSCs) from chronic myeloid leukemia (CML) with a selective growth and survival advantage over normal hematopoietic stem cells (HSCs).1,2 Furthermore, they provide evidence that blocking IL-1 signaling through IL-1 receptor antagonist (IL-1RA)2 or antibody-mediated therapy (anti-IL-1R accessory protein [anti-IL-1RAP])1 has the potential to lead to disease eradication at a stem cell level (see figure). This is extremely important because first-, second-, and third-generation BCR-ABL1 TKIs, although they are capable of inducing sustained molecular and deep molecular remission, are unable to kill quiescent LSCs. Thus, it is becoming evident that a better characterization of the specific pathways of LSCs could lead to the development of new therapies that, if not toxic, will selectively kill CML LSCs. The therapeutic relevance of such studies rests on the fact that a successful CML eradication therapy will not only prevent disease relapse upon TKI discontinuation but also release the majority of patients from life-long and economically challenging TKI therapy and, perhaps, will positively impact prognosis of those patients who become resistant to multiple TKIs and/or undergo blastic transformation.3

We developed a new phage-display based approach, the Large Fragment Phage Display (LFPD), that can be used for mapping conformational epitopes on target molecules of immunological interest. LFPD uses a simplified and more effective phage-display approach in which only a limited set of larger fragments (about 100 aa in length) are expressed on the phage surface. Using the human HER2 oncoprotein as a target, we identified novel B-cell conformational epitopes. The same homologous epitopes were also detected in rat HER2 and all corresponded to the epitopes predicted by computational analysis (PEPITO software), showing that LFPD gives reproducible and accurate results. Interestingly, these newly identified HER2 epitopes seem to be crucial for an effective immune response against HER2-overexpressing breast cancers and might help discriminating between metastatic breast cancer and early breast cancer patients. Overall, the results obtained in this study demonstrated the utility of LFPD and its potential application to the detection of conformational epitopes on many other molecules of interest, as well as, the development of new and potentially more effective B-cell conformational epitopes based vaccines.

Skin represents an attractive target for DNA vaccine delivery because of its natural richness in APCs, whose targeting may potentiate the effect of vaccination. Nevertheless, intramuscular electroporation is the most common delivery method for ECTM vaccination. In this study we assessed whether intradermal administration could deliver the vaccine into different cell types and we analyzed the evolution of tissue infiltrate elicited by the vaccination protocol. Intradermal electroporation (EP) vaccination resulted in transfection of different skin layers, as well as mononuclear cells. Additionally, we observed a marked recruitment of reactive infiltrates mainly 6–24 hours after treatment and inflammatory cells included CD11c+. Moreover, we tested the efficacy of intradermal vaccination against Her2/neu antigen in cellular and humoral response induction and consequent protection from a Her2/neu tumor challenge in Her2/neu nontolerant and tolerant mice. A significant delay in transplantable tumor onset was observed in both BALB/c (p≤0,0003) and BALB-neuT mice (p=0,003). Moreover, BALB-neuT mice displayed slow tumor growth as compared to control group (p<0,0016). In addition, while in vivo cytotoxic response was observed only in BALB/c mice, a significant antibody response was achieved in both mouse models. Our results identify intradermal EP vaccination as a promising method for delivering Her2/neu DNA vaccine.

Perforin (pfp)-mediated cytotoxicity is one of the principal immunosurveillance mechanisms involved in the fight against cancer. However, its importance in spontaneous epithelial cancer is still poorly defined. In this study, we use a realistic mouse model that displays many features that are equivalent to human pathology to evaluate the role of pfp-dependent immunosurveillance by comparing tumor progression in rat ERBB-2 (neu) transgenic, pfp-proficient (neu+/pfp+) or pfp-deficient (neu+/pfp−) BALB/c male mice. Adult neu+/pfp+ males developed poorly differentiated salivary carcinomas, whereas neu+/pfp− males displayed their salivary carcinomas noticeably earlier and showed zones of more highly differentiated tumor, indicating that pfp-mediated immunosurveillance is able not only to delay the growth kinetic of an aggressive epithelial tumor, but also to shape its histology. The role of pfp-mediated immunosurveillance appeared to be of even more dramatic importance against the less aggressive male mammary carcinomas. In neu+/pfp+ males, the incidence of mammary carcinomas was a sporadic and late event. In contrast, in neu+/pfp− males their incidence was four-fold higher. This higher cancer incidence was associated with a 2-fold higher occurrence of persisting mammary remnants, a major risk factor for mammary cancer in male mice, and one that would appear to be due to pfp’s previously unidentified involvement in male mammary gland rejection during embryogenesis. This work thus provides further proof of the complex role that the immune system plays in the body and gives new insight into the pathogenesis of epithelial tumors, demonstrating that the penetrance and malignancy of a tumor may be dramatically affected by pfp-dependent mechanisms.

Attempts to obtain mice reconstituted with a human immune system (HIS) mice, also referred to as HIS mice, date back to the end of 1980s, when mice carrying the Prkdcscid mutation were first used as recipients of human progenitors, with limited success (Shultz et al, 2007). In the last decade, mice with engineered combined immunodeficiencies were obtained and a more efficient engraftment of human hematopoietic stem cells (HSC) was described (Shultz et al, 2007; Manz and Di Santo, 2009; Brehm et al, 2010). Even though the full human reconstitution is generally not achieved, HIS mice have already given valuable results for a better understanding of the differentiation potential of human immune populations (Huntington and Di Santo, 2008; Meek et al, 2010) and for the study of viral human pathogens (Legrand et al, 2009). Moreover, HIS mice are interesting models for human vaccine development (Koo et al, 2009; Becker et al, 2010). Human immune system mice, could provide new experimental models to study the relationships between human tumours and human immune effectors (Brehm et al, 2010; Wege et al, 2011). BALB/c Rag2−/−;Il2rg−/− (hereafter referred to as BRG mice), display a severe combined immunodeficiency, with absence of T, B and NK cells (Nomura et al, 2008). These mice can unveal growth and metastatic ability of human xenografts, otherwise not apparent in mice with partial immunodeficiencies (Nanni et al, 2010). BALB/c Rag2−/−;Il2rg−/− mice have been effectively used to obtain HIS mice (Traggiai et al, 2004; Brehm et al, 2010) and to test antitumour activity of human immune effectors (Thiel et al, 2011). We exploited these features to study the possibility to induce immune responses against human cancer cells by human lymphocytes and their ability to control tumour growth and metastasis. As the tumoural counterpart, we selected a HER-2-positive human cancer cell line. Therapeutic targeting of HER-2-overexpressing cancers with the humanised monoclonal antibody trastuzumab has already entered the clinical practice, but the search for active immunisation strategies against HER-2 is also pursued (Wei et al, 2008). In transgenic models of HER-2-driven mammary carcinogenesis, immune targeting of HER-2 with both active and passive approaches has shown preventive and therapeutic activity (Lollini et al, 2011). Transgenic models are suitable to study, at best, the murine immune response against the transgenic human HER-2 molecule, but cellular or soluble immune effectors elicited in transgenic mice are not of human origin. In the first part of this study we investigated the reconstituting ability of two types of HSC sorted from human cord blood: CD34+ and CD133+ cells. CD34+ progenitors have been extensively used to obtain HIS mice, see for BRG the pioneering study of Traggiai et al (2004). CD133+ HSC engraftment was reported after in vitro culture in growth factor-supplemented medium (Drake et al, 2011), whereas studies with freshly isolated CD133+ HSC in BRG mice and a direct comparison with CD34+ HSC engraftment ability have not been reported. Subsequently, we investigated the ability to elicit an immune response against HER-2-positive human cancer cells.