Sex specific regulation of TSPY-Like 2 in the DNA damage response of cancer cells

Females have a lower probability to develop somatic cancers and a better response to chemotherapy than males. However, the reasons for these differences are still not well understood. The X-linked gene TSPY-Like 2 (TSPYL2) encodes for a putative tumor suppressor protein involved in cell cycle regulation and DNA damage response (DDR) pathways. Here, we demonstrate that in unstressed conditions TSPYL2 is maintained at low levels by MDM2-dependent ubiquitination and proteasome degradation. Upon genotoxic stress, E2F1 promotes TSPYL2 expression and protein accumulation in non-transformed cell lines. Conversely, in cancer cells, TSPYL2 accumulates only in females or in those male cancer cells that lost the Y-chromosome during the oncogenic process. Hence, we demonstrate that while TSPYL2 mRNA is induced in all the tested tumor cell lines after DNA damage, TSPYL2 protein stability is increased only in female cancer cells. Indeed, we found that TSPYL2 accumulation, in male cancer cells, is prevented by the Y-encoded protein SRY, which modulates MDM2 protein levels. In addition, we demonstrated that TSPYL2 accumulation is required to sustain cell growth arrest after DNA damage, possibly contributing to protect normal and female cancer cells from tumor progression. Accordingly, TSPYL2 has been found more frequently mutated in female-specific cancers. These findings demonstrate for the first time a sex-specific regulation of TSPYL2 in the DDR of cancer cells and confirm the existence of sexual dimorphism in DNA surveillance pathways.

Targeting SMYD3 to Sensitize Homologous Recombination-Proficient Tumors to PARP-Mediated Synthetic Lethality

SMYD3 is frequently overexpressed in a wide variety of cancers. Indeed, its inactivation reduces tumor growth in preclinical in vivo animal models. However, extensive characterization in vitro failed to clarify SMYD3 function in cancer cells, although confirming its importance in carcinogenesis. Taking advantage of a SMYD3 mutant variant identified in a high-risk breast cancer family, here we show that SMYD3 phosphorylation by ATM enables the formation of a multiprotein complex including ATM, SMYD3, CHK2, and BRCA2, which is required for the final loading of RAD51 at DNA double-strand break sites and completion of homologous recombination (HR). Remarkably, SMYD3 pharmacological inhibition sensitizes HR-proficient cancer cells to PARP inhibitors, thereby extending the potential of the synthetic lethality approach in human tumors.

•

SMYD3 phosphorylation by ATM favors the formation of HR complexes during DSB response

•

SMYD3 mediates DSB repair by promoting RAD51 recruitment at DNA damage sites

•

SMYD3 inhibition triggers a compensatory PARP-dependent DNA damage response

•

Co-targeting SMYD3/PARP leads to synthetic lethality in HR-proficient cancer cells

Laparoscopic Repair of Boundary Incisional Hernia in a Kidney Transplant Patient: A Safe Tacks-Fibrin Glue Combined Mesh Fixation Technique

BACKGROUND

Incisional hernia in renal transplant patients is a complication that negatively affects the global outcome of transplant and quality of life. The repair of this condition was classically made by open repair with mesh. Increasing evidence suggests that laparoscopic repair could be advocated as the technique of choice in these patients with optimal results. However, the fixation of mesh should be performed by a mixed combination of fibrin sealant (lateral margin of wall defect) and tacks (medial margin). The tacks fixation of the mesh along the lateral margin of the wall defect, close to the graft, is generally difficult for the small size of the remaining aponeurotic plane and dangerous for the underlying presence of the graft.

MATERIALS AND METHODS

A case of incisional hernia in a kidney transplant recipient was repaired by laparoscopic mesh technique. The polypropylene-polyglycolic acid composite mesh was fastened with a mixed technique of absorbable tacks for medial margin of the defect and fibrin sealant for the lateral side in contiguity with graft surface.

RESULTS

The patient was discharged after 4 days. The 6-month follow-up did not show mesh displacement or recurrence of hernia.

CONCLUSIONS

The laparoscopic mesh repair may become the criterion standard for kidney transplant patients affected by incisional hernia. The difficulties of mesh fixation close to the graft can be overcome by the combination of fibrin sealant glue and absorbable tacks at different margins of the wall defect. This technique may offer advantages for this population of patients.

The medical and surgical treatment in secondary and tertiary hyperparathyroidism. Review

INTRODUCTION

Hyperparathyroidism is an alteration of the pathophysiological parathyroid hormone (PTH) secretion due or an independent and abnormal release (primary or tertiary hyperparathyroidism) by the parathyroid or an alteration of calcium homeostasis that stimulates the excessive production of parathyroid hormone (secondary hyperparathyroidism).

AIMS

There is not a standard, clinical or surgical, treatment for hyperparathyroidism. We review current diagnostic and therapeutic methods.

DISCUSSION

In secondary hyperparathyroidism (2HPT) there is a progressive hyperplasia of the parathyroid glands and an increased production of parathyroid hormone. Several causes are proposed: chronic renal insufficiency, vitamin D deficiency, malabsorption syndrome. The tertiary hyperparathyroidism (3HPT) is considered a state of excessive autonomous secretion of PTH due to long-standing 2HPT and it's usually the result of a lack of suppression in the production of PTH. The pathophysiological implications are both skeletal and extraskeletal: it damages the cardiovascular system, nervous system, immune, hematopoietic and endocrine system. The introduction of new drugs has improved the survival of these patients, allowing the inhibition of the synthesis of PTH. Indication for surgical treatment is unresponsive medical therapy.

CONCLUSIONS

There are no large prospective studies that comparing the medical and surgical treatment. The choice is not unique and we have to consider the singolar case and the clinical condition of the patient.

A novel crosstalk between CCAR2 and AKT pathway in the regulation of cancer cell proliferation

Human CCAR2 has recently emerged as having a pivotal role in the DNA damage response, promoting apoptosis and repair of heterochromatic DNA breaks. However, less is known about the function of CCAR2 in tumor formation and cancer progression. Here, we demonstrate, for the first time, that CCAR2 loss inhibits the proliferation of cancer cells, but preserves the growth of normal cells. Investigating the mechanisms responsible for this differential effect, we found that CCAR2 depletion specifically impairs the activation of AKT pathway in cancer cells, but not in normal cells, by reducing AKT phosphorylation on Ser473. This effect is achieved through the transcriptional upregulation of TRB3 gene and accumulation of TRB3 protein, which then binds to and inhibits the phosphorylation and activation of AKT. The defective activation of AKT finally results in reduced GSK3β phosphorylation, prevention of G1/S transition and inhibition of cancer cell growth. These results establish an important role for CCAR2 in cancer cells proliferation and could shed new light on novel therapeutic strategies against cancer, devoid of detrimental side effects.

Retina-derived POU domain factor 1 coordinates expression of genes relevant to renal and neuronal development

Retina-derived POU domain Factor 1 (RPF-1), a member of POU transcription factor family, is encoded by POU6F2 gene, addressed by interstitial deletions at chromosome 7p14 in Wilms tumor (WT). Its expression has been detected in developing kidney and nervous system, suggesting an early role for this gene in regulating development of these organs. To investigate into its functions and determine its role in transcriptional regulation, we generated an inducible stable transfectant from HEK293 cells. RPF-1 showed nuclear localization, elevated stability, and transactivation of promoters featuring POU consensus sites, and led to reduced cell proliferation and in vivo tumor growth. By addressing the whole transcriptome regulated by its induction, we could detect a gross alteration of gene expression that is consistent with promoter occupancy predicted by genome-wide Chip-chip analysis. Comparison of bound regulatory regions with differentially expressed genes allowed identification of 217 candidate targets. Enrichment of divergent octamers in predicted regulatory regions revealed promiscuous binding to bipartite POUS and POUH consensus half-sites with intervening spacers. Gel-shift competition assay confirmed the specificity of RPF-1 binding to consensus motifs, and demonstrated that the Ser-rich region upstream of the POU domain is indispensable to achieve DNA-binding. Promoter-reporter activity addressing a few target genes indicated a dependence by RPF-1 on transcriptional response. In agreement with its expression in developing kidney and nervous system, the induced transcriptome appears to indicate a function for this protein in early renal differentiation and neuronal cell fate, providing a resource for understanding its role in the processes thereby regulated.

CCAR2/DBC1 is required for Chk2-dependent KAP1 phosphorylation and repair of DNA damage

Cell cycle and apoptosis regulator 2 (CCAR2, formerly known as DBC1) is a nuclear protein largely involved in DNA damage response, apoptosis, metabolism, chromatin structure and transcription regulation. Upon DNA lesions, CCAR2 is phosphorylated by the apical kinases ATM/ATR and this phosphorylation enhances CCAR2 binding to SIRT1, leading to SIRT1 inhibition, p53 acetylation and p53-dependent apoptosis. Recently, we found that also the checkpoint kinase Chk2 and the proteasome activator REGγ are required for efficient CCAR2-mediated inhibition of SIRT1 and induction of p53-dependent apoptosis.

Here, we report that CCAR2 is required for the repair of heterochromatic DNA lesions, as cells knock-out for CCAR2 retain, at late time-points after genotoxic treatment, abnormal levels of DNA damage-associated nuclear foci, whose timely resolution is reinstated by HP1β depletion. Conversely, repair of DNA damages in euchromatin are not affected by CCAR2 absence.

We also report that the impairment in heterochromatic DNA repair is caused by defective Chk2 activation, detectable in CCAR2 ablated cells, which finally impacts on the phosphorylation of the Chk2 substrate KAP1 that is required for the induction of heterochromatin relaxation and DNA repair.

These studies further extend and confirm the role of CCAR2 in the DNA damage response and DNA repair and illustrate a new mechanism of Chk2 activity regulation. Moreover, the involvement of CCAR2 in the repair of heterochromatic DNA breaks suggests a new role for this protein in the maintenance of chromosomal stability, which is necessary to prevent cancer formation.

Bimodal regulation of p21(waf1) protein as function of DNA damage levels

Human p21^Waf1 protein is well known for being transcriptionally induced by p53 and activating the cell cycle checkpoint arrest in response to DNA breaks. Here we report that p21^Waf1 protein undergoes a bimodal regulation, being upregulated in response to low doses of DNA damage but rapidly and transiently degraded in response to high doses of DNA lesions. Responsible for this degradation is the checkpoint kinase Chk1, which phosphorylates p21^Waf1 on T145 and S146 residues and induces its proteasome-dependent proteolysis. The initial p21^Waf1 degradation is then counteracted by the ATM-Chk2 pathway, which promotes the p53-dependent accumulation of p21^Waf1 at any dose of damage. We also found that p21^Waf1 ablation favors the activation of an apoptotic program to eliminate otherwise irreparable cells. These findings support a model in which in human cells a balance between ATM-Chk2-p53 and the ATR-Chk1 pathways modulates p21^Waf1 protein levels in relation to cytostatic and cytotoxic doses of DNA damage.

Bone resorption in kidney transplant recipients

Early diagnosis of persistent hyperparathyroidism (HP) following kidney transplantation may prevent worsening of osteodystrophy and potential damage to the graft. We evaluated the utility of collagen pyridinoline (PYD) and deoxypyridinoline (DPD) urinary cross-links beyond the common HP markers to evaluate 70 selected stable recipients between 1997 and 2006 who were divided into 2 group depending on the immunosuppressive protocol. All patients showed elevated levels of urinary cross-links even though calcemia and phosphoremia values were normal. Their mean creatinine level was slightly increased. Data were assessed as mean values +/- SD. All variables underwent a correlation matrix analysis and a stepwise regression, with posttransplant intact parathyroid hormone (iPTH) as the dependent variable and other variables as regressors. A statistically significant correlation was observed between PYD and alkaline phosphatase (ALP; P = .0026, r = .41); PYD and DPD (P = .015, r = .34); pre- and posttransplant iPTH (P = .024, r = .31); and creatinine and ALP (P = .024, r = .31). Taking the groups separately, there were significant correlations between PYD and ALP (P = .0076, r = .42); PYD and DPD (P = .017, r = .38); ALP and posttransplant iPTH (P = .038, r = .33); osteocalcin (OC) and posttransplant iPTH (P = .048, r = .32); and pre- and posttransplant iPTH (P = .019, r = .37) among subjects in the first group, whereas subjects in the second group showed a correlation between posttransplant iPTH and age at transplantation (P = .032, r = .61). In conclusion, we showed that urinary cross-links may be helpful to reveal bone resorption in kidney recipients when usual bone metabolism parameters do not demonstrate hyperparathyroidism.

CHK2 kinase in the DNA damage response and beyond

The serine/threonine kinase CHK2 is a key component of the DNA damage response. In human cells, following genotoxic stress, CHK2 is activated and phosphorylates >20 proteins to induce the appropriate cellular response, which, depending on the extent of damage, the cell type, and other factors, could be cell cycle checkpoint activation, induction of apoptosis or senescence, DNA repair, or tolerance of the damage. Recently, CHK2 has also been found to have cellular functions independent of the presence of nuclear DNA lesions. In particular, CHK2 participates in several molecular processes involved in DNA structure modification and cell cycle progression. In this review, we discuss the activity of CHK2 in response to DNA damage and in the maintenance of the biological functions in unstressed cells. These activities are also considered in relation to a possible role of CHK2 in tumorigenesis and, as a consequence, as a target of cancer therapy.

Chk2 and REGγ-dependent DBC1 regulation in DNA damage induced apoptosis

Human DBC1 (Deleted in Breast Cancer 1; KIAA1967; CCAR2) is a protein implicated in the regulation of apoptosis, transcription and histone modifications. Upon DNA damage, DBC1 is phosphorylated by ATM/ATR on Thr454 and this modification increases its inhibitory interaction with SIRT1, leading to p53 acetylation and p53-dependent apoptosis. Here, we report that the inhibition of SIRT1 by DBC1 in the DNA damage response (DDR) also depends on Chk2, the transducer kinase that is activated by ATM upon DNA lesions and contributes to the spreading of DNA damage signal. Indeed we found that inactivation of Chk2 reduces DBC1-SIRT1 binding, thus preventing p53 acetylation and DBC1-induced apoptosis. These events are mediated by Chk2 phosphorylation of the 11S proteasome activator REGγ on Ser247, which increases REGγ-DBC1 interaction and SIRT1 inhibition. Overall our results clarify the mechanisms underlying the DBC1-dependent SIRT1 inhibition and link, for the first time, Chk2 and REGγ to the ATM-DBC1-SIRT1 axis.

Histologic effects of University of Wisconsin two-layer method preservation of rat pancreas

Marginal donors represent a poorly utilized source of organs for transplantation despite their availability. The key is to reduce the ischemic damage in the effort to improve organ quality. This study investigated the histologic effects after in situ perfusion of preservation with a two-layer method compared with the classic University of Wisconsin preservation in term of tissue integrity and number of viable exocrine cells in the rat pancreas both after exsanguination and at 8 weeks of cryopreservation. Pancreata harvested from 60 rats were collected using 3 methods: two-layer method following University of Wisconsin perfusion; exsanguination; and classic University of Wisconsin perfusion/storage. In addition to histologic analysis of collected pancreata, we analyzed the number of CK19(+) cells and their viability using chi-square tests with values P < .05 considered to be significant. Rat pancreas histology showed as University of Wisconsin in situ perfusion and preservation by the two-layer method to be more effective to maintain the morphologic integrity of both exocrine and endocrine tissues. There were a larger number of CK19(+) cells with good viability. Moreover, the effects of oxygenation were visible in pancreas biopsies preserved after exsanguination. In situ University of Wisconsin perfusion and preservation for 240 minutes with the two-layer method yielded greater numbers and viability of CK19(+) cells even after 8 weeks of cryopreservation.

DBC1 phosphorylation by ATM/ATR inhibits SIRT1 deacetylase in response to DNA damage

Human DBC1 (deleted in breast cancer-1; KIAA1967) is a nuclear protein that, in response to DNA damage, competitively inhibits the NAD(+)-dependent deacetylase SIRT1, a regulator of p53 apoptotic functions in response to genotoxic stress. DBC1 depletion in human cells increases SIRT1 activity, resulting in the deacetylation of p53 and protection from apoptosis. However, the mechanisms regulating this process have not yet been determined. Here, we report that, in human cell lines, DNA damage triggered the phosphorylation of DBC1 on Thr454 by ATM (ataxia telangiectasia-mutated) and ATR (ataxia telangiectasia and Rad3-related) kinases. Phosphorylated DBC1 bound to and inhibited SIRT1, resulting in the dissociation of the SIRT1-p53 complex and stimulating p53 acetylation and p53-dependent cell death. Indeed, DBC1-mediated genotoxicity, which was shown in knockdown experiments to be dependent on SIRT1 and p53 expression, was defective in cells expressing the phospho-mutant DBC1(T454A). This study describes the first post-translational modification of DBC1 and provides new mechanistic insight linking ATM/ATR to the DBC1-SIRT1-p53 apoptotic axis triggered by DNA damage.

A case report of a difficult dissection of the iliac vessels conducted by means of the harmonic scalpel during a kidney transplantation

BACKGROUND

The "difficult" preparation of iliac vessels in the kidney transplant recipient caused by a perivascular fibrosis with satellite lymphadenopathy is sometimes burdened by post-transplant complications (lymphocele, seroma and hematoma). Both iliac vascular adhesions and satellite lymphoadenopaty are often due to reiterate femoral cannulation aimed to hemodialysis.

PATIENTS AND METHODS

The case report concerns a 60 years old female uremic patient, on dialysis for about 4 years with perivascular fibrosis and pelvic lymphadenopathy caused by bilateral femoral artery catheterization. In the course of kidney transplant, preparation of the iliac vessels was performed by ultrasonic scalpel. In the case we handled there was no incidence of immediate, medium and long term post operative complications, with a considerable reduction of the operative time in the vascular dissection performed without ligation. Often the long dialytic period, the same nephropathy, reiterative femoral catheterization determine perivascular fibrosis and/or consensual lymphadenopathy. In these cases, in light of initial experience, the use of ultrasonic scalpel enables easy dissection by the coagulative synthesis not only of vascular compartment but also of the lymphatic duct whose leakage, particularly in these cases, creates a favourable condition to hematoma and/or lymphocele formation. These complications, although rarely jeopardize patient's life, however, may affect the outcome of transplantation in terms of morbidity and survival of the organ. The use of ultrasonic scalpel ensures total control of vascular and lymphatic compartment coagulation, alongside a reduction in the time of surgical dissection.

A protein phosphatase feedback mechanism regulates the basal phosphorylation of Chk2 kinase in the absence of DNA damage

The checkpoint kinase Chk2 is an effector component of the ATM-dependent DNA damage response (DDR) pathway. The activation of Chk2 by genotoxic stress involves its phosphorylation on T68 by ATM and additional auto/transphosphorylations. Here we demonstrate that in unperturbed cells, chemical inhibition of Chk2 by VRX0466617 (VRX) enhances the phosphorylation of Chk2-T68 throughout the cell cycle phases. This event, dependent on the presence of ATM and catalytically functional Chk2, is not consequential to DNA damage, as neither gamma-H2AX nuclear foci nor increased ATM activation is detected in VRX-treated cells, suggesting the involvement of other regulatory proteins. As serine/threonine protein phosphatases (PPs) regulate the phosphorylation and deactivation of proteins of the DDR pathway, we analyzed their role in phospho-T68-Chk2 regulation. We found that intracellular inhibition of PP1 and PP2A-like activities by okadaic acid markedly raised the accumulation of Chk2-pT68 without DNA damage induction, and this phenomenon was also seen when PP1-C, PP2A-C, and Wip1/PPM1D were simultaneously knockdown by siRNA. Altogether, these data indicate a novel mechanism in undamaged cells where PPs function to maintain the balance between ATM and its direct substrate Chk2 through a regulatory circuit.

[Differentiated microcarcinoma of the thyroid gland]

BACKGROUND

The thyroid microcarcinoma is a tumor with maximum diameter of 10 mm (WHO). For the most part is not clinically palpable and not evident by imaging investigations. The papillary microcarcinoma is the most common form of thyroid cancer, followed by follicular microcarcinoma. The aim of our study is to assess the frequency of microcarcinoma, the association of benign thyroid disease himself and the controversial surgery.

PATIENTS AND METHODS

We analyzed 391 patients (321 F and 70 M) who underwent total thyroidectomy from 2004 to 2009 at a Unit of General Surgery, Uremic and Organ Transplant, Hospital of Palermo.

RESULTS

42 carcinomas were detected, of which 24 PTMC and 1 follicular microcarcinoma. The PTMC was associated with cancer in only 2 cases (papillary carcinoma and parathyroid carcinoma) in the remaining thyroid tissue was suffering from benign disease (20 goiters, 3 Hashimoto thyroiditis, a trabecular adenoma). TALK: Controversial is still the type of surgery to be performed in case of differentiated thyroid microcarcinomas, as well as the indication is still debated to lymphadenectomy.

CONCLUSIONS

Papillary microcarcinoma of the thyroid in our series, represents 57% of all thyroid cancers. Microcarcinoma and benign thyroid disease association (76.92% of cases) was high. The therapeutic attitude adopted by us was total thyroidectomy associated with conservative lymphadenectomy in the presence of palpable lymph nodes, instead to abstaining in the absence of clinical evidence of nodal metastases.

Primary malignant fibrous histiocytoma of the mesocolon transversum

Primary malignant fibrous histiocytoma (MFH) is a rare and biologically aggressive tumor. Differential diagnosis must include cystic neoplasms of the pancreas (mucinous and serous cystoadenoma or cystocarcinoma), cystic lymphangioma or mesothelioma and retroperitoneal haematoma. Making the right diagnosis preoperatively may be often difficult, but MFH may be suspected when a huge retroperitoneal mass is found at imaging in elderly patients. We report a case of a primary abdominal MFH originating from the mesocolon transversum.

Informed consent in high-risk renal transplant recipients

Before performing a clinical, diagnostic, and/or therapeutic action, the doctor is required to provide the patient with a bulk of information defined as informed consent. This expression was used for the first time in 1957 during a court case in California and the two words--informed and consent--are used together to underline the fact that the patient cannot give his or her true consent without first receiving correct information concerning the medical act in question. With regard to the medicolegal aspects governing organ transplants, despite the bulk of detailed work performed by health service workers involved in this surgical field with the aim of preparing adequate informed consent models, this has not yet been accompanied by the necessary legislative development. The informed consent model to be presented to the kidney transplant candidate should include a detailed description of the recipient's comorbidity and should aim at reducing the number of medicolegal actions, which have become more and more frequent in the last few years due to the ever increasing number of patients considered as suitable for transplantation. Informed consent, therefore, should not be a mere bureaucratic formality to be obtained casually, but should be carefully stipulated together with the patient by the transplant surgeon. It is, in fact, an indispensable condition for transforming a potentially illegal action, that is, the violation of an individual's psychophysical integrity, into a legal one.

Use of intraperitoneal ePTFE Gore dual-mesh plus in a giant incisional hernia after kidney transplantation: a case report

We evaluated the incidence of and predisposing factors for an incisional hernia after kidney transplantation. Numerous techniques have been used to repair postoperative fascial dehiscences or simple incisional hernias, but no clear treatment exists for giant hernias. Our aim was to obtain (1) a safe procedure to repair a large abdominal defect and reinforce the surrounding, fragile zones and (2) a simple, rapid technique to reduce the operative time. Herein we have described the surgical repair of a giant incisional hernia using intraperitoneal Gore ePTFE dual-mesh plus (Gore-Tex; W. L. Gore, Flagstaff, Ariz, USA) in a 55-year-old man status-post renal transplantation. Total necrosis of distal graft ureter had caused a giant urinoma. The patient was reexplored on day 2 posttransplantation with a primary fascial approximation. Thirty days after transplantation we discovered a large incisional hernia and performed a repair. No drain was used. The patient continued immunosuppressive therapy (cyclosporine, mycophenolate mofetil, prednisolone) and was discharged on postoperative day 4 with no complications. An ultrasonographic follow-up at 1 year revealed the prosthesis to be correctly positioned. Incisional hernia is not rare after renal transplantation but the real incidence is unknown. Immunosuppressive therapy, prolonged pretransplantation dialysis, obesity, and diabetes are probably the major causes of incisional hernias in these patients. Surgical complications of renal transplantation surgery, such as wound hematoma, urinoma, and lymphocele, are the most important predisposing factors for an incisional hernia. The use of intraperitoneal ePTFE dual-mesh is feasible, safe, and easy to repair a large incisional hernia in a kidney transplant patient.

REGgamma proteasome activator is involved in the maintenance of chromosomal stability

REGgamma is a member of the 11S regulatory particle that activates the 20S proteasome. Studies in REGgamma deficient mice indicated an additional role for this protein in cell cycle regulation and proliferation control. In this paper we demonstrate that REGgamma protein is equally expressed throughout the cell cycle, but undergoes a distinctive subcellular localization at mitosis. Thus, while in interphase cells REGgamma is nuclear, in telophase cells it localizes on chromosomes, suggesting a role in mitotic progression. Furthermore, we found that REGgamma overexpression weakens the mitotic arrest induced by spindle damage, allowing premature exit from mitosis, whereas REGgamma depletion has the opposite effect, thus reflecting a new REGgamma function, unrelated to its role as proteasome activator. Additionally, we found that primary cells from REGgamma-/- mice and human fibroblasts with depleted expression of REGgamma or overexpressing a dominant negative mutant unable to activate the 20S proteasome, demonstrated a marked aneuploidy (chromosomal gains and losses), supernumerary centrosomes and multipolar spindles. These findings thus underscore a previously uncharacterized function of REGgamma in centrosome and chromosomal stability maintenance.

Use of monitoring intraoperative parathyroid hormone during parathyroidectomy in patients on waiting list for renal transplantation

This report describes the use of intraoperative parathyroid hormone (ioPTH) assay during parathyroidectomy for patients with secondary hyperparathyroidism on the waiting list for renal transplantation. The levels of ioPTH were determined among waiting list patients undergoing subtotal parathyroidectomy and tertiary hyperparathyroidism patients undergoing procedures. The levels of ioPTH were significantly reduced at 10 minutes by 59.7,3% among with secondary hyperparathyroidism and 68.9% among tertiary hyperparathyroidism. A 15 minutes it was 85% in secondary hyperparathyroidism and 89.7% in tertiary hyperparathyroidism. A decrement of 50% in basal values at 10 minutes and 85% decrement or more at 15 minutes was predictive for the success of abnormal parathyroid gland removal. The application of this technique during subtotal parathyroidectomy results was useful to predict a correct excision of abnormal parathyroid glands among patients with secondary hyperparathyroidism on the waiting list and for tertiary hyperparathyroidism patients.

[The role of colonoscopy in patient follow-up after surgery for colorectal cancer. A retrospective study and review of the literature]

To improve survival rate after colon or rectum resection for cancer patients should be strictly followed up in order to identify possible local disease relapse or metachronous neoplasia. From October 2002 to January 2006, 864 patients had undergone colonoscopy and 68 were treated surgically for colorectal adenocarcinoma. Of these, 36 were men and 32 women, with a mean age of 63 years. Nineteen of the patients underwent a left colectomy, 28 an anterior resection, 18 a right colectomy and 3 a resection of the transverse colon. For all these patients follow-up program include a colonoscopy performed annually for the first two years, and subsequently, if the results were negative, after a further three and then five years. Out of 68 patients, 2 showed suspect anastomotic recurrence, which proved to be granulomas at the histological examination. In addition, in 11 cases, there were 3 right colon adenomatous polyps, 2 transverse colon polyps (one villous and the other tubular), 5 descending colon polyps (three tubular and two villous) and 1 tubulo-villous polyp of the rectum. No metachronous neoplasias were observed. An examination of the data resulting from our own 68 cases shows that, in spite of the fact that no local disease relapse or metachronous neoplasia was observed, the identification of 11 polyps would suggest that the use of colonoscopy in such patients might be the gold standard for early diagnosis of recurrences and new polyps.

Biochemical and cellular characterization of VRX0466617, a novel and selective inhibitor for the checkpoint kinase Chk2

VRX0466617 is a novel selective small-molecule inhibitor for Chk2 discovered through a protein kinase screening program. In this study, we provide a detailed biochemical and cellular characterization of VRX0466617. We show that VRX0466617 blocks the enzymatic activity of recombinant Chk2, as well as the ionizing radiation (IR)-induced activation of Chk2 from cells pretreated with the compound, at doses between 5 and 10 micromol/L. These doses of VRX0466617 inhibited, to some extent, the phosphorylation of Chk2 Ser(19) and Ser(33-35), but not of Chk2 Thr(68), which is phosphorylated by the upstream ataxia-telangiectasia mutated (ATM) kinase. Interestingly, VRX0466617 induced the phosphorylation of Chk2 Thr(68) even in the absence of DNA damage, arising from the block of its enzymatic activity. VRX0466617 prevented the IR-induced Chk2-dependent degradation of Hdmx, concordant with the in vivo inhibition of Chk2. Analysis of ATM/ATM and Rad3-related substrates Smc1, p53, and Chk1 excluded a cross-inhibition of these kinases. VRX0466617 did not modify the cell cycle phase distribution, although it caused an increase in multinucleated cells. Whereas VRX0466617 attenuated IR-induced apoptosis, in short-term assays it did not affect the cytotoxicity by the anticancer drugs doxorubicin, Taxol, and cisplatin. These results underscore the specificity of VRX0466617 for Chk2, both in vitro and in vivo, and support the use of this compound as a biological probe to study the Chk2-dependent pathways.

Differential roles of ATM- and Chk2-mediated phosphorylations of Hdmx in response to DNA damage

The p53 tumor suppressor plays a major role in maintaining genomic stability. Its activation and stabilization in response to double strand breaks (DSBs) in DNA are regulated primarily by the ATM protein kinase. ATM mediates several posttranslational modifications on p53 itself, as well as phosphorylation of p53's essential inhibitors, Hdm2 and Hdmx. Recently we showed that ATM- and Hdm2-dependent ubiquitination and subsequent degradation of Hdmx following DSB induction are mediated by phosphorylation of Hdmx on S403, S367, and S342, with S403 being targeted directly by ATM. Here we show that S367 phosphorylation is mediated by the Chk2 protein kinase, a downstream kinase of ATM. This phosphorylation, which is important for subsequent Hdmx ubiquitination and degradation, creates a binding site for 14-3-3 proteins which controls nuclear accumulation of Hdmx following DSBs. Phosphorylation of S342 also contributed to optimal 14-3-3 interaction and nuclear accumulation of Hdmx, but phosphorylation of S403 did not. Our data indicate that binding of a 14-3-3 dimer and subsequent nuclear accumulation are essential steps toward degradation of p53's inhibitor, Hdmx, in response to DNA damage. These results demonstrate a sophisticated control by ATM of a target protein, Hdmx, which itself is one of several ATM targets in the ATM-p53 axis of the DNA damage response.

DNA damage-induced cell cycle regulation and function of novel Chk2 phosphoresidues

Chk2 kinase is activated by DNA damage to regulate cell cycle arrest, DNA repair, and apoptosis. Phosphorylation of Chk2 in vivo by ataxia telangiectasia-mutated (ATM) on threonine 68 (T68) initiates a phosphorylation cascade that promotes the full activity of Chk2. We identified three serine residues (S19, S33, and S35) on Chk2 that became phosphorylated in vivo rapidly and exclusively in response to ionizing radiation (IR)-induced DNA double-strand breaks in an ATM- and Nbs1-dependent but ataxia telangiectasia- and Rad3-related-independent manner. Phosphorylation of these residues, restricted to the G(1) phase of the cell cycle, was induced by a higher dose of IR (>1 Gy) than that required for phosphorylation of T68 (0.25 Gy) and declined by 45 to 90 min, concomitant with a rise in Chk2 autophosphorylation. Compared to the wild-type form, Chk2 with alanine substitutions at S19, S33, and S35 (Chk2(S3A)) showed impaired dimerization, defective auto- and trans-phosphorylation activities, and reduced ability to promote degradation of Hdmx, a phosphorylation target of Chk2 and regulator of p53 activity. Besides, Chk2(S3A) failed to inhibit cell growth and, in response to IR, to arrest G(1)/S progression. These findings underscore the critical roles of S19, S33, and S35 and argue that these phosphoresidues may serve to fine-tune the ATM-dependent response of Chk2 to increasing amounts of DNA damage.

[Laparoscopic treatment of adrenal myelolipoma: case report and review of the literature]

Adrenal myelolipoma is a rare benign, non-functioning tumor consisting of fat and hematopoietic tissues. In January 2005 we had observed an adrenal myelolipoma in 70 year old man. During the follow-up for bladder urothelioma, an abdominal CT revaled a well delineated 4x4 cm homogeneous fatty mass in the right suprarenal area with negative attenuation values. The functional study of adrenal gland was normal. The patient underwent videolaparoscopic right adrenalectomy (Gagner technique). Postoperative course was uneventful. The istological diagnosis showed adrenal myelolipoma. We conclude that videolaparoscopic adrenalectomy should be considered the gold standard treatment for benign adrenal lesions.

PTFE Mesh in Renal Allograft Compartment Syndrome

We report a case of anuria in a 42-year-old female kidney transplant patient that occurred secondary to extrinsic compression from a large kidney being placed extraperitoneally in a small iliac fossa. Prompt reexploration in the immediate postoperative period resulted in salvage of the graft with restoration of kidney function. The abdominal wall was reconstructed using prosthetic mesh, which decreased the compartment pressure within the iliac fossa sufficiently to allow the renal vein patency and the kidney perfusion. We think that this tension-free surgical technique should be applied in those cases in which the retroperitoneal space is less than the size of the kidney to avoid renal allograft compartment syndrome or incisional hernia.

Intraoperative Parathyroid Hormone Monitoring During Parathyroidectomy for Hyperparathyroidism in Waiting List and Kidney Transplant Patients

This report describes the use of the intraoperative parathyroid hormone (ioPTH) assay during parathyroidectomy in waiting list and transplanted patients. ioPTH levels were determined in 40 patients on the waiting list for kidney transplantation with secondary hyperparathyroidism who underwent subtotal parathyroidectomy and 9 transplanted patients with tertiary hyperparathyroidism who underwent removal of hyperplasic glands. Rapid PTH levels decreased significantly at each time period; the percentage decrease in rapid PTH levels was 61.3% among patients with IPT II and 70.2% in patients with IPT III at 10 minutes and 86.5% in patients with IPT II and 91% in patients with IPT III at 15 minutes after excision of hypersecreting parathyroid tissue. A decrease of 50% or more from baseline PTH levels at 10 minutes and/or a decrease of 85% or more at 15 minutes predicted successful removal of abnormal parathyroid glands. The application of this technique during subtotal parathyroidectomy has proved useful for correct excision of parathyroid glands among waiting list patients with IPT II, while in kidney transplant patients with IPT III it allowed removal of only the pathological glands with a limited surgical approach.

Use of Marginal Donors in Kidney Transplantation: Our Experience

The use of elderly donors has been advocated to expand the organ donor pool because of increased needs and the organ shortage. The aim of this study was to analyze whether the use of elderly donors and marginal kidneys affected the outcome of renal transplantations. Herein we presented data on 126 kidney transplantations performed from January 1996 to September 2003 using 32 marginal donors (group A) and 94 ideal donors (group B). We analyzed the medical and surgical complications and the graft survivals at a median follow-up of 18 months. Medical and surgical complications occurred in 22% and 5% versus 7% and 4% in groups A and B, respectively. The mean cold ischemia time and the mean age were greater for patients undergoing kidney transplantations from marginal donors. No differences were observed in graft survival in groups A and B. In conclusion, our data suggested that with an appropriate strategy and a correct selection of patients, marginal kidneys can be safely used to decrease the gap between demand and supply.

[Laparoscopic cholecystectomy in uremic patients]

The aim of this study was to evaluate the effectiveness of the laparoscopic cholecystectomy performed in two uremic patients with gallstones. From January to July 2004, 15 patients with gallstones underwent to laparoscopic cholecystectomy (LC). Two patients had chronic renal failure on haemodyalisis: a symptomatic fourty-two old woman, which had primitive hyperparathyroidism and primitive hyperaldosteronism, and asymptomatic transplant candidate fifty-five old man. No minor and major complications occurred and both patients were discharged 4 days after LC. Even in uremic patients the L. C. must be the gold standard for the treatment of gallstones both symptomatic and asymptomatic.

Activation of ATM and Chk2 kinases in relation to the amount of DNA strand breaks

The diverse checkpoint responses to DNA damage may reflect differential sensitivities by molecular components of the damage-signalling network to the type and amount of lesions. Here, we determined the kinetics of activation of the checkpoint kinases ATM and Chk2 (the latter substrate of ATM) in relation to the initial yield of genomic DNA single-strand (SSBs) and double-strand breaks (DSBs). We show that doses of gamma-radiation (IR) as low as 0.25 Gy, which generate vast numbers of SSBs but only a few DSBs per cell (<8), promptly activate ATM kinase and induce the phosphorylation of the ATM substrates p53-Ser15, Nbs1-Ser343 and Chk2-Thr68. The full activation of Chk2 kinase, however, is triggered by treatments inflicting >19 DSBs per cell (e.g. 1 Gy), which cause Chk2 autophosphorylation on Thr387, Chk2-dependent accumulation of p21waf1 and checkpoint arrest in the S phase. Our results indicate that, in contrast to ATM, Chk2 activity is triggered by a greater number of DSBs, implying that, below a certain threshold level of lesions (<19 DSBs), DNA repair can occur through ATM, without enforcing Chk2-dependent checkpoints.

MRE11 mutations and impaired ATM-dependent responses in an Italian family with ataxia-telangiectasia-like disorder

Hypomorphic mutations of the MRE11 gene are the hallmark of the radiosensitive ataxia-telangiectasia-like disorder (ATLD). Here, we describe a new family with two affected siblings, ATLD5 and ATLD6, now aged 37 and 36, respectively. They presented with late onset cerebellar degeneration slowly progressing until puberty and absence of telangiectasias, and were cancer-free. Both patients were wild-type for ATM and NBS1, but compound heterozygotes for MRE11 gene mutations [1422C-->A, T481K; 1714C-->T, R571X]. The 1422C-->A allele was inherited from the mother, whereas the 1714C-->T, allele paternally inherited, was apparently null as a result of nonsense-mediated mRNA decay (NMD). Interestingly, the 1714C-->T mutation is the same as previously identified in an unrelated English ATLD family (probands ATLD3 and ATLD4), suggesting an important role for NMD in saving potentially lethal mutations. Lymphoblastoid cell lines (LCLs) derived from ATLD5 and ATLD6 were normal for ATM, but defective for Mre11, Rad50 and Nbs1 (the MRN complex) protein expression. Their response to gamma-radiation was abnormal, as evidenced by the enhanced radiosensitivity, attenuated autophosphorylation of ATM-S1981 and phosphorylation of the ATM targets p53-S15 and Smc1-S966, failure to form Mre11 nuclear foci and defective G1 checkpoint arrest. The fibroblasts, but not LCLs, from ATLD5 and ATLD6 showed an impaired ATM-dependent Chk2 phosphorylation. These findings further underscore the interconnection between ATM activity and MRN function, which rationalizes the clinical similarity between ataxia-telangiectasia (A-T) and ATLD.

[Laparoscopic adrenalectomy: our preliminary experience]

INTRODUCTION

In 1992, Gagner described the first laparoscopic adrenalectomy. Since then this technique has been more and more widely employed and several studies confirmed its advantages, comparing to the traditional approach, in terms of reduction of mean hospital stay and therefore of the health expense.

PATIENTS AND METHODS

The Authors' preliminary experience spreads from March to November 2003 when 4 patients were studied and thus underwent a transperitoneal laparoscopic adrenalectomy: 2 of them were affected by Cushing syndrome, 1 by pheochromocytoma in MEN and 1 by an incidentaloma. The transabdominal access in lateral decubitus with 4 trocars was performed.

RESULTS

No complication was reported with a minimal need of analgesic drugs. The mean hospital stay was 4 days and all patients were discharged 48 hours after surgery. The mean diameter of nodules was 40 +/- 30 mm. The definitive histological examination showed 2 cortical adenomas, 1 diffuse cortical hyperplasia and 1 pheochromocytoma.

CONCLUSIONS

This preliminary report confirms the optimal results of other experienced authors. Further interventions will be necessary for improvements and technical requirements.

[The surgical treatment of nodular thyroid lesions: our experience. Analysis of 462 cases]

Nodular thyroid lesions are the most frequent endocrine diseases in the general population. The surgical procedure is indicated for nodular thyroid tissue degeneration, or when the suppressive pharmacologic therapy is less efficient, even if sometimes both factors are associated. In Authors' study 462 patients were observed who underwent surgical procedures for thyroid diseases between January 1997-April 2003. In the thyroid pathology, either uninodular or multinodular, the surgical therapy adopted is total thyroidectomy, according to other Authors. The aim of total thyroidectomy is to avoid recurrence and simplify long term pharmacologic treatment. Although the question about the surgical approach (total thyroidectomy vs lobectomy) is still open in the case of single monolateral lesions, on the basis of their experience the Authors believe that the first is the best procedure. For diffused or malignant nodular thyroid pathology, on the contrary, total thyroidectomy is widely adopted.

Karyopherin-alpha2 protein interacts with Chk2 and contributes to its nuclear import

Chk2 is a nuclear protein kinase involved in the DNA damage-induced ataxia telangiectasia mutated-dependent checkpoint arrest at multiple cell cycle phases. Searching for Chk2-binding proteins by a yeast two-hybrid system, we identified a strong interaction with karyopherin-alpha2 (KPNA-2), a gene product involved in active nuclear import of proteins bearing a nuclear localization signal (NLS). This finding was confirmed by glutathione S-transferase pull-down and co-immunoprecipitation assays. Of the three predicted Chk2 NLSs, located at amino acids 179-182 (NLS-1), 240-256 (NLS-2), and 515-522 (NLS-3), only the latter mediated the interaction with KPNA-2 in the yeast two-hybrid system, and in particular with its C terminus. Unlike mutations in NLS-1 or NLS-2, which left the nuclear localization of Chk2 unaffected, mutations in NLS-3 caused a cytoplasmic relocalization, indicating that the NLS-3 motif acts indeed as NLS for Chk2 in vivo. Finally, co-transfection experiments with green fluorescent protein (GFP)-Chk2 and wild type or mutant KPNA-2 confirmed the role of KPNA-2 in nuclear import of Chk2.

The cell cycle-regulated protein human GTSE-1 controls DNA damage-induced apoptosis by affecting p53 function

GTSE-1 (G2 and S phase-expressed-1) protein is specifically expressed during S and G2 phases of the cell cycle. It is mainly localized to the microtubules and when overexpressed delays the G2 to M transition. Here we report that human GTSE-1 (hGTSE-1) protein can negatively regulate p53 transactivation function, protein levels, and p53-dependent apoptosis. We identified a physical interaction between the C-terminal regulatory domain of p53 and the C-terminal region of hGTSE-1 that is necessary and sufficient to down-regulate p53 activity. Furthermore, we provide evidence that hGTSE-1 is able to control p53 function in a cell cycle-dependent fashion. hGTSE-1 knock-down by small interfering RNA resulted in a S/G2-specific increase of p53 levels as well as cell sensitization to DNA damage-induced apoptosis during these phases of the cell cycle. Altogether, this work suggests a physiological role of hGTSE-1 in apoptosis control after DNA damage during S and G2 phases through regulation of p53 function.

[Our trend in conservative surgery in differentiated carcinoma of the thyroid]

AIM OF THE STUDY

Report as contribution to the controversy between supporters of total thyroidectomy versus "less than total" thyroidectomy.

MATERIALS AND METHODS

42 patient operated on over six years; 35 treated with total thyroidectomy, 7 with lobohystmectomy.

RESULTS

In the patients who underwent total thyroidectomy we observed recurrent nerve lesions in 5.7%, hypoparathyroidism in 14.3% and 1 lymph nodal relapse (it was a cancer stay III); in patients who underwent lobohystmectomy, we observed 1 temporary recurrent nerve palsy (14.2%) and 1 lymph nodal relapse (14.2%).

DISCUSSION

The choice between total thyroidectomy and lobohystermectomy depends upon different goals: reduction in risk of relapse in total thyroidectomy, to minimize complications in lobohystmectomy. In our series the risk of lymph nodal relapse seems to depend more on biological characters of the tumour than surgical tech of lymphadenectomy; however, this occurrence does not change prognosis.

CONCLUSIONS

In our experience, potential multifocality of the disease, low risk of hyatrogenic lesions and easy postoperatory management make total thyroidectomy the our preferred technique. Informed consensus is mandatory in order to involve the patients to the best choice.

[Non-toxic multinodular goitre: which surgery?]

AIM OF THE STUDY

Evaluation of total thyroidectomy, subtotal thyroidectomy and lobectomy in the management of multinodular non-toxic goitre.

MATERIALS AND METHODS

225 patients: 101 total thyroidectomies, 64 sub-total thyroidectomies, 29 lobo-hystmectomies. Hemorrages, recurrent nerve palsies, post-operatory hypocalcemias, clinical and ultrasonographic relapses, undesired effects of ormonal therapy and hypothyroidism after partial resection (considered risk factor for recurrence) have been pointed out.

RESULTS

All three procedures showed a low incidence of recurrent nerve palsy; lobectomy didn't show post-operatory hypocalcemia, that appeared respectively in 26.6% and 23% after sub-total and total thyroidectomy. Recurrence's percentage in patients followed-up, was 18.2% after lobectomy and 12.2% after sub-total thyroidectomy, but in that group we observed 46.9% of hypothyroidism (vs. 9.1% after lobectomy) and 8.6% of undesired effects of therapy. Reoperations showed inferior laringeal palsy and post-operatory hypocalcemia significantly more elevated.

DISCUSSION

Compared to lobectomy, total thyroidectomy showed higher risk of hypoparathyroidism; compared to subtotal thyroidectomy, it showed on all occasions less incidence of complications. Endocrinological follow-up is easier after total thyroidectomy.

CONCLUSIONS

According to our results, we deem the indications for lobectomy have to be limited to the patients having solitary nodule, undoubtedly benign, without familiarity or other environmental risk factor of goitre.

Chk2 activation dependence on Nbs1 after DNA damage

The checkpoint kinase Chk2 has a key role in delaying cell cycle progression in response to DNA damage. Upon activation by low-dose ionizing radiation (IR), which occurs in an ataxia telangiectasia mutated (ATM)-dependent manner, Chk2 can phosphorylate the mitosis-inducing phosphatase Cdc25C on an inhibitory site, blocking entry into mitosis, and p53 on a regulatory site, causing G(1) arrest. Here we show that the ATM-dependent activation of Chk2 by gamma- radiation requires Nbs1, the gene product involved in the Nijmegen breakage syndrome (NBS), a disorder that shares with AT a variety of phenotypic defects including chromosome fragility, radiosensitivity, and radioresistant DNA synthesis. Thus, whereas in normal cells Chk2 undergoes a time-dependent increased phosphorylation and induction of catalytic activity against Cdc25C, in NBS cells null for Nbs1 protein, Chk2 phosphorylation and activation are both defective. Importantly, these defects in NBS cells can be complemented by reintroduction of wild-type Nbs1, but neither by a carboxy-terminal deletion mutant of Nbs1 at amino acid 590, unable to form a complex with and to transport Mre11 and Rad50 in the nucleus, nor by an Nbs1 mutated at Ser343 (S343A), the ATM phosphorylation site. Chk2 nuclear expression is unaffected in NBS cells, hence excluding a mislocalization as the cause of failed Chk2 activation in Nbs1-null cells. Interestingly, the impaired Chk2 function in NBS cells correlates with the inability, unlike normal cells, to stop entry into mitosis immediately after irradiation, a checkpoint abnormality that can be corrected by introduction of the wild-type but not the S343A mutant form of Nbs1. Altogether, these findings underscore the crucial role of a functional Nbs1 complex in Chk2 activation and suggest that checkpoint defects in NBS cells may result from the inability to activate Chk2.