Maria Linda Cruceru

Therapy targets in glioblastoma and cancer stem cells: lessons from haematopoietic neoplasms.

Despite intense efforts to identify cancer‐initiating cells in malignant brain tumours, markers linked to the function of these cells have only very recently begun to be uncovered. The notion of cancer stem cell gained prominence, several molecules and signalling pathways becoming relevant for diagnosis and treatment. Whether a substantial fraction or only a tiny minority of cells in a tumor can initiate and perpetuate cancer, is still debated. The paradigm of cancer‐initiating stem cells has initially been developed with respect to blood cancers where chronic conditions such as myeloproliferative neoplasms are due to mutations acquired in a haematopoietic stem cell (HSC), which maintains the normal hierarchy to neoplastic haematopoiesis. In contrast, acute leukaemia transformation of such blood neoplasms appears to derive not only from HSCs but also from committed progenitors that cannot differentiate. This review will focus on putative novel therapy targets represented by markers described to define cancer stem/initiating cells in malignant gliomas, which have been called ‘leukaemia of the brain’, given their rapid migration and evolution. Parallels are drawn with other cancers, especially haematopoietic, given the similar rampant proliferation and treatment resistance of glioblastoma multiforme and secondary acute leukaemias. Genes associated with the malignant conditions and especially expressed in glioma cancer stem cells are intensively searched. Although many such molecules might only coincidentally be expressed in cancer‐initiating cells, some may function in the oncogenic process, and those would be the prime candidates for diagnostic and targeted therapy. For the latter, combination therapies are likely to be envisaged, given the robust and plastic signalling networks supporting malignant proliferation.

Cancer stem cells: Involvement in pancreatic cancer pathogenesis and perspectives on cancer therapeutics

Pancreatic cancer is one of the most aggressive and lethal malignancies. Despite remarkable progress in understanding pancreatic carcinogenesis at the molecular level, as well as progress in new therapeutic approaches, pancreatic cancer remains a disease with a dismal prognosis. Among the mechanisms responsible for drug resistance, the most relevant are changes in individual genes or signaling pathways and the presence of highly resistant cancer stem cells (CSCs). In pancreatic cancer, CSCs represent 0.2%-0.8% of pancreatic cancer cells and are considered to be responsible for tumor growth, invasion, metastasis and recurrence. CSCs have been extensively studied as of late to identify specific surface markers to ensure reliable sorting and for signaling pathways identified to play a pivotal role in CSC self-renewal. Involvement of CSCs in pancreatic cancer pathogenesis has also highlighted these cells as the preferential targets for therapy. The present review is an update of the results in two main fields of research in pancreatic cancer, pathogenesis and therapy, focused on the narrow perspective of CSCs.

Anti-cancer Therapies in High Grade Gliomas

High grade gliomas represent one of the most aggressive and treatment-resistant types of human cancer, with only 1–2 years median survival rate for patients with grade IV glioma. The treatment of glioblastoma is a considerable therapeutic challenge; combination therapy targeting multiple pathways is becoming a fast growing area of research. This review offers an up-to-date perspective of the literature about current molecular therapy targets in high grade glioma, that include angiogenic signals, tyrosine kinase receptors, nodal signaling proteins and cancer stem cells related approaches. Simultaneous identification of proteomic signatures could provide biomarker panels for diagnostic and personalized treatment of different subsets of glioblastoma. Personalized medicine is starting to gain importance in clinical care, already having recorded a series of successes in several types of cancer; nonetheless, in brain tumors it is still at an early stage.

signal transduction molecule patterns indicating potential glioblastoma therapy approaches

Purpose The expression of an array of signaling molecules, along with the assessment of real-time cell proliferation, has been performed in U87 glioma cell line and in patients’ glioblastoma established cell cultures in order to provide a better understanding of cellular and molecular events involved in glioblastoma pathogenesis. Experimental therapy was performed using a phosphatidylinositol-3′-kinase (PI3K) inhibitor. Patients and methods xMAP technology was employed to assess expression levels of several signal transduction molecules and real-time xCELLigence platform for cell behavior. Results PI3K inhibition induced the most significant effects on global signaling pathways in patient-derived cell cultures, especially on members of the mitogen-activated protein-kinase family, P70S6 serine-threonine kinase, and cAMP response element-binding protein expression and further prevented tumor cell proliferation. Conclusion The PI3K pathway might be a prime target for glioblastoma treatment.

Decreased expression of APAF-1 and increased expression of cathepsin B in invasive pituitary adenoma.

Purpose Apoptotic protease-activating factor-1 (APAF-1) and cathepsin B are important functional proteins in apoptosis; the former is involved in the intrinsic (mitochondrial) pathway, while the latter is associated with both intrinsic and extrinsic pathways. Changes in the expression of apoptosome-related proteins could be useful indicators of tumor development since a priori defects in the mitochondrial pathway might facilitate the inception and progression of human neoplasms. Our aim was to evaluate the profiles of APAF-1 and cathepsin B in relation with other molecules involved in apoptosis/proliferation and to correlate them with the aggressive behavior of invasive pituitary adenomas. Materials and methods APAF-1 and cathepsin B were assessed in tissue samples from 30 patients with pituitary adenomas, of which 16 were functional adenomas and 22 were invasive adenomas. Results A positive relationship between high proliferation and invasiveness was observed in invasive pituitary adenomas when compared to their noninvasive counterparts (Ki-67 labeling index – 4.72% versus 1.75%). Decreased expression of APAF-1 was recorded in most of the invasive adenomas with a high proliferation index, while the cathepsin B level was elevated in this group. We have noticed a negative correlation between the low level of APAF-1 and invasiveness (63.63%; P<0.01); at the same time, a positive correlation between cathepsin B expression and invasiveness (59.09%; P<0.01) was found. In all, 81.25% out of the total APAF-1-positive samples were cathepsin B negative (P<0.01); 76.92% out of the total cathepsin B-positive samples were APAF-1-negative (P<0.01). These results were reinforced by an apoptosis protein array examination, which showed inhibition of the extrinsic apoptotic pathway in an invasive pituitary adenoma. Conclusion A bidirectional–inverted relationship between APAF-1 and cathepsin B expressions was noticed. One might hypothesize that shifting the balance between mediators of cell death could result in changes in tumor behavior.

Circulating biomarker panels for targeted therapy in brain tumors

An important goal of oncology is the development of cancer risk-identifier biomarkers that aid early detection and target therapy. High-throughput profiling represents a major concern for cancer research, including brain tumors. A promising approach for efficacious monitoring of disease progression and therapy could be circulating biomarker panels using molecular proteomic patterns. Tailoring treatment by targeting specific protein-protein interactions and signaling networks, microRNA and cancer stem cell signaling in accordance with tumor phenotype or patient clustering based on biomarker panels represents the future of personalized medicine for brain tumors. Gathering current data regarding biomarker candidates, we address the major challenges surrounding the biomarker field of this devastating tumor type, exploring potential perspectives for the development of more effective predictive biomarker panels.

Angiogenic markers: molecular targets for personalized medicine in pituitary adenoma

AIM Pituitary adenomas are typically slow-growing and histologically benign tumors that can occasionally behave in a malignant-like manner, invading adjacent structures or recurring after treatment. Using protein analysis methods and multiplex xMAP assays, we aimed to find out if these particular types of tumors express angiogenic markers VEGF and basic FGF (bFGF), which are associated with tumor growth and invasiveness, and quantify them in order to establish their usefulness as biomarkers. MATERIALS & METHODS We have analysed the expression of angiogenic markers VEGF and bFGF in serum and tissue specimens from 66 pituitary adenomas (43 invasive and 23 noninvasive). For serum analysis, we used xMAP and ELISA, and for tissue analysis, we performed histopathology and immunohistochemistry. RESULTS & CONCLUSION We measured the serum angiogenic factors in pituitary adenomas. The quantification methods revealed significant differences between pituitary adenoma patients and controls, for both VEGF (212.4 vs 112.5 pg/ml in controls) and bFGF (mean value of 12.6 vs 10.8 pg/ml in controls), and also differentiated between invasive and noninvasive adenomas (p < 0.05). The tissue expression of VEGF and bFGF strongly correlated with their serum level increase. Our findings can be further developed into methods for selection of patients suitable for personalized, antiangiogenic therapy.

Role of Apaf-1 and cathepsin B in pituitary tumor progression

Aims: Apaf-1 (apoptotic protease-activating factor 1), is commonly known as an indicator of apoptosis regulation. It is the core protein of the apoptosome and its dosage is also critical in various cancer types. The aim of our study was to investigate the expression of Apaf-1 and cathepsin B (as caspase-dependent and non-caspase-dependent) effectors of cell death, in order to correlate them with the invasivity of pituitary adenoma. Design: Immunohistochemical analysis was performed on 30 paraffin-embeded pituitary adenomas: 21 functioning and 9 non-functioning; 22 with local invasiveness, 16 invasive in cavernous sinus; 4 were recidives. The following antibodies were used: Apaf-1– rabbit polyclonal (1:100), cathepsin B – mouse monoclonal NCL-Cath-B (CB131) (1:40), and Ki67– MIB1 (1:50). Apoptosis was measured as apoptotic index by TUNEL method. Results: A positive relation between high proliferation and high apoptotic index in invasive adenomas was revealed. The loss of Apaf-1 expression was observed in most of the invasive adenoma with increased Ki67 proliferative index. In low-grade invasive tumors Apaf-1 was expressed in variable degree with a zonal distribution. Most of the non-invasive adenoma presented positive Apaf-1 reaction, with zonal or diffuse aspect. On the contrary, cathepsin B was commonly expressed with a granular pattern, routinely lying on the plasma membrane, in invasive pituitary tumors. In cells undergoing apoptosis, cathepsin B appeared diffusely re-distributed in the cytosol. A negative correlation between Apaf-1 and invasiveness was noted. On the other hand, a positive correlation between cathepsin-B and invasiveness was recorded. Conclusion: These data demonstrated an inverse correlation between Apaf-1 and cathepsin B expressions. Shifting the balance between cell death mediators might result in changes in tumor behavior.