Intestinal adenocarcinoma originating from an undiagnosed Meckel's diverticulum.

Meckel's diverticulum is a congenital anomaly leading to the formation of a true diverticulum in the distal small intestine. Though most are asymptomatic and discovered incidentally, Meckel's diverticuli can give rise to a wide range of symptoms. Rarely, this can be a malignancy, most commonly a carcinoid tumor. Other cancers have also been reported, with adenocarcinomas being particularly rare. Here, we report the case of a 62-year-old man presenting to the emergency room with vague gastrointestinal symptoms. Subsequent workup revealed a 3 cm mass in the distal jejunum/proximal ileum, which was located within a previously undiagnosed Meckel's diverticulum. The mass was sent to pathology, who confirmed an adenocarcinoma arising from a small bowel diverticulum. This case serves as an important reminder of the malignant potential of a Meckel's diverticulum and adds to the ongoing discussion regarding whether prophylactic diverticulectomy should be recommended to patients with a known Meckel's diverticulum.

Republication: Targeting PI3KC2ß Impairs Proliferation and Survival in Acute Leukemia, Brain Tumours and Neuroendocrine Tumours.

BACKGROUND: Eight human catalytic phosphoinositide 3-kinase (PI3K) isoforms exist which are subdivided into three classes. While class I isoforms have been well-studied in cancer, little is known about the functions of class II PI3Ks. MATERIALS AND METHODS: The expression pattern and functions of the class II PI3KC2ß isoform were investigated in a panel of tumour samples and cell lines. RESULTS: Overexpression of PI3KC2ß was found in subsets of tumours and cell lines from acute myeloid leukemia (AML), glioblastoma multiforme (GBM), medulloblastoma (MB), neuroblastoma (NB), and small cell lung cancer (SCLC). Specific pharmacological inhibitors of PI3KC2ß or RNA interference impaired proliferation of a panel of human cancer cell lines and primary cultures. Inhibition of PI3KC2ß also induced apoptosis and sensitised the cancer cells to chemotherapeutic agents. CONCLUSION: Together, these data show that PI3KC2ß contributes to proliferation and survival in AML, brain tumours and neuroendocrine tumours, and may represent a novel target in these malignancies.

Synthesis, Characterization, Quantum-Chemical Calculations and Cytotoxic Activity of 1,8-Naphthalimide Derivatives with Non-Protein Amino Acids.

BACKGROUND: The 1,8-Naphthalimides constitute an important class of biologically active, DNAbinding compounds. There are no available data on the synthesis of 1,8-naphthalimide derivatives with nonprotein amino acids and their biological activity. The aim of this paper was to determine the synthesis, structural characterization and cytotoxic activity of new 1-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)cycloalkane-1- carboxylic acids with 5-, 6-, 7-, 8- and 12-membered rings as well as 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)- yl)adamantane-2-carboxylic acid and 1-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-1,2,3,4-tetrahydronaphthalene- 1-carboxylic acid. METHODS: The target compounds were obtained by an interaction of 1,8-naphthalic anhydride with a series of non-protein amino acids. The optimized geometry and harmonic vibrational frequencies have been calculated by DFT employing B3LYP functional using 6-31G(d,p) basis set. An ab initio (MP2 and Hartee-Fock) and DFT (different functionals) using several basis sets have been applied for NMR calculations. The cytotoxic effects of the synthesized compounds are assessed against two human tumor cell lines, namely K-562 (chronic myeloid leukemia) and HUT-78 (cutaneous T-cell lymphoma) after 72 h exposure, using the MTT-dye reduction assay. The apoptogenic effects and the ability to modulate the NFκB-signaling pathways were determined using commercially available ELISA kits. RESULTS: All compounds inhibited the growth of malignant cells at micromolar concentrations whereby compound 4b (1-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)cyclohexane-1-carboxylic acid) demonstrated superior activity in both cell lines with IC50 values comparable to those of the reference anticancer drug melphalan. CONCLUSION: New 1,8-naphthalimide derivatives with non-protein amino acids were successfully synthesized. Quantum-chemical calculations were performed to elucidate the structure of the newly synthesized compounds. There is a proper alignment between theoretical and experimental results. The cytotoxicity of the synthesized products against two human tumor cell lines, namely K-562 and HUT-78 was evaluated. All compounds inhibited the growth of malignant cells at micromolar concentrations. The pharmacodynamics evaluation of compound 4b showed that its cytotoxicity is mediated by induction of apoptosis and inhibition of NFκB-signaling.

Cushing's Syndrome: A Historic Review of the Treatment Strategies and Corresponding Outcomes in a Single Tertiary Center over the Past Half-Century.

Cushing's syndrome (CS) is associated with serious comorbidities and an increased mortality rate that could be reduced only if strict biochemical control is achieved. The aim of this study was to show the 50-year experience of a single tertiary center in the management of CS patients - the different treatment modalities used over the years and the corresponding outcomes. It was a retrospective study of a large cohort of patients from the Bulgarian CS database: 613 patients (374 with ACTH-dependent and 239 with ACTH-independent CS). Pituitary surgery was applied to 242 patients with Cushing's disease (CD) with initial remission rate of 74% of which 10% relapsed. Approximately 36% manifested with active disease during the long-term follow-up (26% with persistent disease, 10% relapses) most of which were subjected to a secondary treatment (13.6% to pituitary resurgery, 14% to pituitary radiotherapy, and 5.4% to bilateral adrenalectomy). A total of 294 CD patients received medical therapy with overall remission rates for the most commonly used drugs: dopamine agonists 20%, pasireotide 30%, and ketoconazole 63%. Significant improvement of results was achieved by combining drugs with different mechanisms of action. Regardless of the progress in the neurosurgery and radiotherapy techniques and new drugs discovery, the management of patients with CS remains a real challenge for physicians. Not only patients with adrenal carcinoma but also significant percentage of subjects with persistent and recurrent Cushing's disease often require a polymodal approach and the efforts of a multidisciplinary highly qualified, experienced, and motivated team in order to achieve a long-term remission.

Optic Nerve Glioma in Two Sisters with Family History of Neurofibromatosis Type 1.

Optic nerve glioma (ONG) is associated in 10% of patients with neurofibromatosis (NF) type 1. To date no consensus has been reached regarding the therapeutic approach and prevention of visual impairment in these patients. Reports in the literature vary from a conservative approach (observation) to the use of single treatment modalities or multimodality protocols of surgical removal, radiotherapy, and/or chemotherapy. We present our experience with two siblings with ONG whose mother carries cutaneous stigmata of NF type 1. The younger sister was diagnosed 3 years after the treatment of the older sibling following recommended imaging for screening. Postoperative follow-up for 11 and 15 years, respectively, demonstrated lack of tumor regrowth and preserved vision in the contralateral eye. We discuss the treatment strategy in pediatric patients with orbital ONG associated with NF type 1.

Study on the Synthesis, Characterization and Bioactivities of 3-Methyl-9'-fluorenespiro-5-hydantoin.

This work describes a method for synthesis, as well as in vitro antiproliferative and antibacterial investigation of 3-methyl-9'-fluorenespiro-5-hydantoin. The structure of the substituted fluorenylspirohydantoin derivative was verified by UV-Vis, FT-IR, Raman, (1)H-NMR and (13)C-NMR spectroscopy, and by using a combination of 2D NMR experiments, which included (1)H-(1)H COSY, HMQC and HMBC sequences. The geometry of the compound was optimized by the B3LYP density functional with 6-31G(d) basis set and the (1)H and (13)C NMR spectra were predicted with the HF/6-31G(d) calculations at the optimized geometry. The anticancer activity of the 3-methyl-9'-fluorenespiro-5-hydantoin was determined in suspension cell lines originating from tumors in humans (WERI-Rb-1). The cytotoxic effect was evaluated by WST-assay (Roche Applied Science). The antimicrobial effect of the compound against Gram-negative, Gram-positive bacteria and the yeast Candida albicans was investigated.

Synthesis and in vitro activity of platinum(II) complexes of two fluorenylspirohydantoins against a human tumour cell line.

This paper presents a method for synthesis and cytotoxicity of new platinum(II) complexes of (9'-fluorene)-spiro-5-hydantoin (L1) and (9'-fluorene)-spiro-5-(2-thiohydantoin) (L2). The new obtained complexes were studied by elemental analysis: ultraviolet-visible, attenuated total reflection Fourier transform infrared (ATR-FTIR), and 1H- and 13C-NMR for Pt(II) compounds and additionally Raman spectroscopy for free ligands. Based on the experimental data, the most probable structure of the complexes is suggested. In the present study, we have examined cytotoxic activity of (9'-fluorene)-spiro-5-hydantoin (L1) and (9'-fluorene)-spiro-5-(2-thiohydantoin) (L2) and their Pt(II) complexes on the retinoblastoma cell line WERI-Rb-1.

Evaluation of prognostic utility of MIB-1 and p53 expression in pituitary adenomas: correlations with clinical behaviour and follow-up results.

Pituitary adenomas (PAs) show a broad clinicomorphological spectrum. The proliferation activity, evaluated by MIB-1 labelling index (LI), and p53 expression have been pointed as predictive markers for invasiveness and progression. The aim of this study was to evaluate the proliferation rate and p53 expression and to look for any relationships with the clinical behaviour and follow-up results in a series of Bulgarian patients with PAs. A total of 93 patients with PAs (81 hormone-secreting, 12 non-functioning), who were operated on and followed up for a period of five years, were included. The MIB-1 LI and p53 expressions were determined by immunohistochemistry and correlated with various clinical and tumour variables. The whole group of PAs showed a low proliferation rate with evident variations in a small number of cases (MIB-1 LI - 0.50 ± 0.56, from 0.1 to 3.30). MIB-1 LI correlated with tumour size (p = 0.012) and was positively related with male gender (p = 0.23) and partial surgical resection (p = 0.036). We found no significant differences regarding the age, functional activity, invasion (n = 33), expansion (n = 37) and tumour recurrences (seven cases). Only 10 cases (10.8%) showed a focal, nuclear p53 immunoreactivity. The p53 positive tumours had higher proliferation rate (p = 0.0001) but no relationship with the other clinical and tumour variables. Among all cases, there was only one case with higher MIB-1 LI (3.3%), positive p53 expression and tumour recurrence after surgery. Our results show that most PAs have a low proliferation rate and lack of p53 expression, as well as no relationship with tumour invasion or postsurgical progression.

Phosphoinositide 3-kinase C2ß regulates RhoA and the actin cytoskeleton through an interaction with Dbl.

The regulation of cell morphology is a dynamic process under the control of multiple protein complexes acting in a coordinated manner. Phosphoinositide 3-kinases (PI3K) and their lipid products are widely involved in cytoskeletal regulation by interacting with proteins regulating RhoGTPases. Class II PI3K isoforms have been implicated in the regulation of the actin cytoskeleton, although their exact role and mechanism of action remain to be established. In this report, we have identified Dbl, a Rho family guanine nucleotide exchange factor (RhoGEF) as an interaction partner of PI3KC2ß. Dbl was co-immunoprecipitated with PI3KC2ß in NIH3T3 cells and cancer cell lines. Over-expression of Class II phosphoinositide 3-kinase PI3KC2ß in NIH3T3 fibroblasts led to increased stress fibres formation and cell spreading. Accordingly, we found high basal RhoA activity and increased serum response factor (SRF) activation downstream of RhoA upon serum stimulation. In contrast, the dominant-negative form of PI3KC2ß strongly reduced cell spreading and stress fibres formation, as well as SRF response. Platelet-derived growth factor (PDGF) stimulation of wild-type PI3KC2ß over-expressing NIH3T3 cells strongly increased Rac and c-Jun N-terminal kinase (JNK) activation, but failed to show similar effect in the cells with the dominant-negative enzyme. Interestingly, epidermal growth factor (EGF) and PDGF stimulation led to increased extracellular signal-regulated kinase (Erk) and Akt pathway activation in cells with elevated wild-type PI3KC2ß expression. Furthermore, increased expression of PI3KC2ß protected NIH3T3 from detachment-dependent death (anoikis) in a RhoA-dependent manner. Taken together, these findings suggest that PI3KC2ß modulates the cell morphology and survival through a specific interaction with Dbl and the activation of RhoA.

Targeting PI3KC2ß impairs proliferation and survival in acute leukemia, brain tumours and neuroendocrine tumours.

BACKGROUND: Eight human catalytic phosphoinositide 3-kinase (PI3K) isoforms exist which are subdivided into three classes. While class I isoforms have been well-studied in cancer, little is known about the functions of class II PI3Ks. MATERIALS AND METHODS: The expression pattern and functions of the class II PI3KC2ß isoform were investigated in a panel of tumour samples and cell lines. RESULTS: Overexpression of PI3KC2ß was found in subsets of tumours and cell lines from acute myeloid leukemia (AML), glioblastoma multiforme (GBM), medulloblastoma (MB), neuroblastoma (NB), and small cell lung cancer (SCLC). Specific pharmacological inhibitors of PI3KC2ß or RNA interference impaired proliferation of a panel of human cancer cell lines and primary cultures. Inhibition of PI3KC2ß also induced apoptosis and sensitised the cancer cells to chemotherapeutic agents. CONCLUSION: Together, these data show that PI3KC2ß contributes to proliferation and survival in AML, brain tumours and neuroendocrine tumours, and may represent a novel target in these malignancies.

AKT/mTOR pathway activation and BCL-2 family proteins modulate the sensitivity of human small cell lung cancer cells to RAD001.

PURPOSE: The Akt/mammalian target of rapamycin (mTOR) pathway is frequently activated in human cancers and plays an important role in small cell lung cancer (SCLC) biology. We investigated the potential of targeting mTOR signaling as a novel antitumor approach in SCLC. EXPERIMENTAL DESIGN: The expression of mTOR in patient specimens and in a panel of SCLC cell lines was analyzed. The effects on SCLC cell survival and downstream signaling were determined following mTOR inhibition by the rapamycin derivative RAD001 (Everolimus) or down-regulation by small interfering RNA. RESULTS: We found elevated expression of mTOR in patient specimens and SCLC cell lines, compared with normal lung tissue and normal lung epithelial cells. RAD001 treatment impaired basal and growth factor-stimulated cell growth in a panel of SCLC cell lines. Cells with increased Akt pathway activation were more sensitive to RAD001. Accordingly, a constitutive activation of the Akt/mTOR pathway was sufficient to sensitize resistant SCLC cells to the cytotoxic effect of RAD001. In the sensitive cells, RAD001 showed a strong additive effect to the proapoptotic action of the chemotherapeutic agent etoposide. Intriguingly, we observed low Bcl-2 family proteins levels in the SCLC cells with a constitutive Akt pathway activation, whereas an increased expression was detected in the RAD001-resistant SCLC cells. An antisense construct targeting Bcl-2 or a Bcl-2-specific inhibitor was able to sensitize resistant SCLC cells to RAD001. Moreover, SCLC tumor growth in vivo was significantly inhibited by RAD001. CONCLUSION: Together, our data show that inhibiting mTOR signaling with RAD001 potently disrupts growth and survival signaling in human SCLC cells.

Effect of the type of image study (CT or MRI) on some parameters of neuronavigation-assisted procedures.

AIM: The aim of this study was to determine the effect of the applied method of image investigation (CT or MRI) on the following parameters of the neuronavigation (NN) assisted procedure: "number of attempts for registration", "duration of registration" and "registration accuracy". PATIENTS AND METHODS: A total of 195 patients with various cranial pathological lesions underwent neuronavigation-assisted surgery between March 2003 and December 2005 at the Clinic of Neurosurgery of St. I. Rilsky University Hospital, Medical University, Sofia. All of them were included in our study. CT based registration was realized in 81 patients of our series and MR based registration--in 114 patients. The patients were examined and followed up in a standardized manner. We conducted a prospective study on the effect of the type of image investigation (either CT or MRI) on the parameters registration accuracy, number of attempts for registration and duration of registration. Statistical analysis was performed using a one-factor non-parametric rank analysis (Friedman ANOVA) with a factor "type of image study" which had four sublevels: "MR I", "CT", MRI+MRI Angiography" and "MRI+CT". Multiple Hotelling F-contrasts were applied; the level of statistical significance was 95% (Statistica 6.0, 2001, Statsoft, Tulsa, USA). RESULTS: In the series, the best (the lowest digital expression) mean registration accuracy was demonstrated in MRI based neuronavigation (1.6 mm). Besides that, in MRI-NN the number of attempts for registration was smaller and the time necessary for registration was shorter in comparison with CT-NN. In the "MR I+CT" subgroup the mean values of the investigated parameters were lower in comparison with the other three subgroups. Nevertheless, the differences were not statistically significant because of the wide statistical dispersions of the obtained results and the small number of patients investigated in this subgroup. ANOVA did not show statistically significant difference between the number of attempts for registration, the duration of registration and the registration accuracy in CT and MR-based neuronavigation-assisted procedures. CONCLUSION: We did not found any statistically significant differences between CT- and MRI-based neuronavigation with respect to the accuracy and reliability of the methods. The type of image study that should be used for neuronavigation depends on the specific characteristics of the corresponding pathological lesion.

Neuronavigated surgery of intracranial cavernomas--enthusiasm for high technologies or a gold standard?

AIM: The aim of this study was to investigate the effect of neuronavigation on the following parameters: "skin incision", "craniotomy", "intraoperative anatomical orientation", "dissection guiding", "localization of the pathological formation", "assessment of the degree of resection" and "duration of surgical procedure" in resections of intracranial cavernomas and to specify the indications for neuronavigation in their surgical treatment. PATIENTS AND METHODS: The present prospective study included 20 patients with intracranial cavernomas who underwent neuronavigated surgery between March 2003 and December 2005 at the Clinic of Neurosurgery of the "St. I. Rilsky" University Hospital, Medical University, Sofia. The female/male ratio in the series was 9/11 (45%-55%). The patients' mean age was 27.96 +/- 11.61 years (age range 1.2 to 44 years). The patients were examined and followed up in a standard manner. RESULTS: Cavernous malformations were totally removed in 19 patients. One patient with thalamic cavernoma underwent navigated endoscopic biopsy. There was no morbidity or mortality associated with the method. Neuronavigation allowed precise localization and individual design of the skin incision and craniotomy. Neuronavigated intraoperative anatomical orientation, dissection guiding, localization of the pathological formation, and assessment of degree of resection were evaluated as markedly useful. They resulted in excellent surgery results and reduced operation time in comparison with the conventional surgery. CONCLUSION: In intracranial cavernomas frameless stereotaxy provides the surgeon with useful feedback in the preoperative anatomical orientation, the planning and simulation of surgical approach, the intraoperative navigation, in avoiding vital neurovascular structures, in the assessment of the degree of resection and the identification of possible residual parts. That is why cavernous malformations are among the most common indications for cranial neuronavigation.

Cranial neuronavigation--a step forward or a step aside in modern neurosurgery.

Neuronavigation is a result of the introduction and integration of high technologies into modern neurosurgery. The method is becoming increasingly available, and more than ever, its "fashionable", ungrounded application (literally, in each neurosurgical procedure) requires objective evaluation of its real usefulness. The aim of the present survey was to analyze the use of neuronavigation in the general fields of modern cranial neurosurgery. The reliability of the classical method of brain lesion localization was compared to neuronavigated localization. We studied the neuronavigation assisted interventions in tumor surgery, skull-base surgery, biopsies, neuroendoscopy, functional neurosurgery, vascular neurosurgery and surgical procedures in the proximity of functionally important cortical zones. We showed the modern tendencies in neuronavigation and outlined the social and economic aspects of neuronavigation-assisted neurosurgery. A summary of the advantages and disadvantages of frameless stereotaxy is made.

Role of neuronavigation in the resection of intracranial arteriovenous malformations.

AIM: The aim of this study was to investigate the effect of neuronavigation on the following parameters: "skin incision", "craniotomy", "intraoperative anatomical orientation", "dissection guiding", "localization of the pathological formation", "assessment of the degree of resection" and "duration of surgical procedure" in the resection of intracranial arteriovenous malformations (AVMs) and to specify the indications for application of neuronavigation in the surgical treatment of AVMs. METHODS: Five neuronavigation-assisted resections of intracranial AVMs were performed between March 2003 and December 2005 at the Clinic of Neurosurgery of St. I. Rilsky University Hospital, Medical University, Sofia. The female/male ratio in the series was 2:3 (40%:60%). The patients' mean age was 28.2 +/- 18.27 (range 10 to 56) years. The study was prospective in design. Patients were examined and followed in a standardized manner. RESULTS: Arteriovenous malformations were totally removed in all 5 cases of neuronavigation-assisted resections. We did not observe any morbidity or mortality associated with the method. Neuronavigation allowed precise localization and individual design of the skin incision and craniotomy. Neuronavigation facilitated the surgeon during intraoperative anatomical orientation. Dissection guiding, localization of the formation and assessment of the degree of resection were assessed as markedly useful. This resulted in reduced duration of surgery compared to conventional neurosurgery. CONCLUSIONS: In AVMs resection neuronavigation optimizes surgical approach by visualizing the relationship ofAVMs to the skull and various critical anatomical structures. Deep vessel components and nidus margins, especially in the vicinity of the ventricles can be identified precisely. Neuronavigation can improve the early post-operative results in cerebral AVMs reducing operating time and blood loss.

Reconstruction of two bile ducts in a cloaca fashion in living donor liver transplantation.

The presence of two or more hepatic ducts for biliary anastomosis in adult-to-adult right liver transplantation is not uncommon. In the case described here, the graft had two hepatic ducts: one corresponded anatomically to a normal right hepatic duct and the other ran parallel to the proper hepatic duct and drained into its distal to the cystic duct. Because of the small diameter of both duct orifices and the favorable length of the ducts, a cloaca type reconstruction was performed. This allowed the construction of a single and larger orifice for the biliary anastomosis. In case of multiple hepatic ducts of smaller caliber, this technique represents a practical and effective hepatoplasty allowing a single larger anastomosis in the recipient.

Targeting mTOR signaling in lung cancer.

Lung cancer is the leading cause of cancer-related mortality in the world, with more than 1 million deaths per year. Over the past years, lung cancer treatment has been based on cytotoxic agents and an improvement in the outcome and quality of life for patients has been observed. However, it has become clear that additional therapeutic strategies are urgently required in order to provide an improved survival benefit for patients. Two major intracellular signaling pathways, the Ras/Raf/extracellular signal-regulated kinase (Erk) and the phosphoinositide 3-kinase (PI3K)/Akt pathways have been extensively studied in neoplasia, including lung cancer. Furthermore, the study of constitutively activated receptor tyrosine kinases (RTKs) and their downstream signaling mediators has opened a promising new field of investigation for lung cancer treatment. Since both the Ras/Raf/Erk and the PI3K/Akt pathways are downstream of a plethora of activated RTKs, they have been extensively studied for the development of novel anti-tumor agents. Moreover, the mammalian target of rapamycin (mTOR) has been identified as a downstream target of the PI3K/Akt pathway. Rapamycin and its derivatives are highly selective and very potent inhibitors of mTOR and initial pre-clinical and clinical studies have reported encouraging results for different tumor types. Nevertheless for lung cancer, this approach has not been successful yet. Here we will review the molecular basis of PI3K/Akt/mTOR signaling in lung cancer and further discuss the therapeutic potential of multi-targeted strategies involving mTOR inhibitors.

Targeting receptor tyrosine kinase signalling in small cell lung cancer (SCLC): what have we learned so far?

Small cell lung cancer (SCLC) is an aggressive form of lung cancer, which represents 13% of all cases and is strongly associated with cigarette smoking. The survival of SCLC patients is dismal and has not greatly improved in the last 20 years, despite advances in chemotherapy regimens and a better understanding of SCLC biology. The development of resistance to chemotherapy and metastasis are commonly recognized as important causes of poor clinical outcome in SCLC. Targeting receptor tyrosine kinase (RTK) signalling represents an attractive approach to develop new drugs for SCLC, in view of the accumulating data demonstrating that polypeptide growth factors play a key role in driving SCLC cell proliferation, chemoresistance and metastasis. The insulin-like growth factor-I receptor (IGF-IR), c-Kit, vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR) have been identified as potential drug targets in SCLC. Moreover, downstream signalling mediators of RTKs, such as phosphoinositide 3-kinase (PI3K)/Akt and the mammalian target of rapamycin (mTOR) may also represent attractive candidate molecules for anti-cancer therapies in SCLC. Here we will review the available data concerning results with RTK inhibitors in SCLC and the clinical trials undertaken to investigate the potential of these compounds as anti-tumour agents in SCLC.

Recent patents of gene sequences relative to the phosphatidylinositol 3-kinase/Akt pathway and their relevance to drug discovery.

Phosphoinositide 3-kinases (PI3Ks) play an essential role in the signal transduction events initiated by the binding of extracellular signals to their cell surface receptors. There are eight known PI3Ks in humans, which have been subdivided into three classes (I-III). The class I(A) of PI3K comprises the p110alpha, p110beta and p110delta isoforms, which associate with receptor tyrosine kinases (RTKs). On the other hand, the class I(B) PI3K p110gamma is regulated by G-protein-coupled receptors (GPCRs). Gene targeting studies in mice have revealed specific biological functions for the class I(A) p110delta in lymphocyte activation, and the class I(B) p110gamma in inflammatory cell responses. In human cancer, recent reports have described activating mutations in the PIK3CA gene encoding p110alpha, and inactivating mutations in the PTEN gene, a tumor suppressor and antagonist of the PI3K pathway. Thus, individual PI3K isoforms are potential drug targets for a variety of human diseases, including allergies, cancer, rheumatoid arthritis and arterial thrombosis. In this review, we will discuss recent patents relating to class I PI3Ks, including patents on the cDNA sequences of p110gamma and p110delta. Moreover, we will review patents on novel pharmacological PI3K inhibitors and on methods of manipulating T cell responses through PI3K.

Phosphoinositide 3-Kinase C2beta regulates cytoskeletal organization and cell migration via Rac-dependent mechanisms.

Receptor-linked class I phosphoinositide 3-kinases (PI3Ks) induce assembly of signal transduction complexes through protein-protein and protein-lipid interactions that mediate cell proliferation, survival, and migration. Although class II PI3Ks have the potential to make the same phosphoinositides as class I PI3Ks, their precise cellular role is currently unclear. In this report, we demonstrate that class II phosphoinositide 3-kinase C2beta (PI3KC2beta) associates with the Eps8/Abi1/Sos1 complex and is recruited to the EGF receptor as part of a multiprotein signaling complex also involving Shc and Grb2. Increased expression of PI3KC2beta stimulated Rac activity in A-431 epidermoid carcinoma cells, resulting in enhanced membrane ruffling and migration speed of the cells. Conversely, expression of dominant negative PI3KC2beta reduced Rac activity, membrane ruffling, and cell migration. Moreover, PI3KC2beta-overexpressing cells were protected from anoikis and displayed enhanced proliferation, independently of Rac function. Taken together, these findings suggest that PI3KC2beta regulates the migration and survival of human tumor cells by distinct molecular mechanisms.