The Impact of the COVID-19 Pandemic on Colorectal Cancer Patients in a Tertiary Center in Romania. Single Center Retrospective Study.

Background: The novel coronavirus, SARS-COV-2, was first reported in Wuhan, China in the end of 2019. To curb its spread, social distancing measures and new safety regulations were implemented which led to major disruptions in colorectal cancer care. It is however unknown how it influenced the Romanian colorectal cancer care. Methods and Material: We assessed the demographical, clinical, intraoperative and pathological data of our colorectal cancer patients, 302 in total, between 15.03.2019-14.03.2021. The first year's data was considered as the control group and the second one, the study (pandemic) group. Results: We observed a 12% decrease in colorectal cancer hospitalizations in the first year, 38,6% in the first six months. The rate of emergency admissions, colo/ileostomy formatting procedures, palliative resections, clinical metastasis was higher in the pandemic group. More advanced locoregional invasion, a higher tumor stage, higher rate of vascular, perineural invasion, positive resection margin, and a higher lymph node yield was seen after the restrictions were implemented. Conclusion: The COVID-19 pandemic and the response against it had a major effect on the colorectal cancer care in our country. The outcomes of these worse clinical and pathological findings are unknown, but it is important to do further research in this field. We think colorectal cancer care should have an absolute priority in future pandemics.

C-N Bond Formation by Consecutive Continuous-Flow Reductions towards A Medicinally Relevant Piperazine Derivative.

A new, continuous-flow consecutive reduction method was developed for the C-N bond formation in the synthesis of the key intermediate of the antipsychotic drug cariprazine. The two-step procedure consists of a DIBAL-H mediated selective ester reduction conducted in a novel, miniature alternating diameter reactor, followed by reductive amination using catalytic hydrogenation on 5% Pt/C. The connection of the optimized modules was accomplished using an at-line extraction to prevent precipitation of the aluminum salt byproducts.

Origin of the p-process radionuclides 92Nb and 146Sm in the early solar system and inferences on the birth of the Sun.

The abundances of (92)Nb and (146)Sm in the early solar system are determined from meteoritic analysis, and their stellar production is attributed to the p process. We investigate if their origin from thermonuclear supernovae deriving from the explosion of white dwarfs with mass above the Chandrasekhar limit is in agreement with the abundance of (53)Mn, another radionuclide present in the early solar system and produced in the same events. A consistent solution for (92)Nb and (53)Mn cannot be found within the current uncertainties and requires the (92)Nb/(92)Mo ratio in the early solar system to be at least 50% lower than the current nominal value, which is outside its present error bars. A different solution is to invoke another production site for (92)Nb, which we find in the α-rich freezeout during core-collapse supernovae from massive stars. Whichever scenario we consider, we find that a relatively long time interval of at least ∼ 10 My must have elapsed from when the star-forming region where the Sun was born was isolated from the interstellar medium and the birth of the Sun. This is in agreement with results obtained from radionuclides heavier than iron produced by neutron captures and lends further support to the idea that the Sun was born in a massive star-forming region together with many thousands of stellar siblings.

Locally advanced breast cancer in Eastern European developing countries.

AIM: Breast cancer is known as the most frequent cancer type among women. In several developing countries advanced stage cases present an increase trend, despite the global provisions of screening for early detection. The aim was to investigate patients with locally advanced breast cancers, in a developing country from eastern Europe. MATERIAL AND METHODS: A retrospective study was performed, including patients diagnosed with breast cancer who underwent surgical intervention, during 2007-2017. Besides demographic data, surgical techniques were investigated. Within histopathological data tumor size, type and grade were examined. We also investigated lymph node status and patient's hormonal parameters. RESULTS: We examined 1008 patients diagnosed with benign and malignant mammary gland tumors over 11 years. After excluding benign tumors, inflammatory cancers, biopsies, recurrent breast cancers and initial stages, 125 patients remained eligible. Exulceration and hemorrhage were observed in 64 (51.2%) locally advanced cases. Resection of the pectoralis major muscle was realized in 12.8% due to tumoral infiltration. DISCUSSION: Locally advanced breast cancer represents approximately 5% in developed countries. Within our results, this rate was 27.9%. This discrepancy is given by the regular national mammary screening programs within several developed countries. CONCLUSIONS: In the developing countries locally advanced breast cancer presents a continuous increase and hemorrhagic exulcerated types are not uncommon. Due to the poor health education and sometimes inadequate health care in eastern Europe, just a few patients have benefited of neoadjuvant therapy and preoperative mammography was performed in a small number of patients. KEY WORDS: Brest Cancer, Locally Advanced.

Incidental parathyroidectomy is a frequent complication of thyroid surgery. A retrospective study of 3065 patients.

AIM: The aim of the present study is to investigate the incidence of accidental parathyroidectomy and the connection between the type of surgery, or the resected piece sent for histopathological examination and the number of accidentally excised parathyroid glands. MATERIAL AND METHODS: Patients who had thyroid surgery between January 2005 and December 2014 and were admitted to a surgery clinic from Targu Mures, Romania, were enrolled in this study. For statistical analysis we used Chi-squared test, Student's t-test and ANOVA test, with a p value < 0.05 considered statistically significant. RESULTS: A total of 3065 patients (315 males, 2750 females) were included in our study, with a mean age of 49.66±13.73. The frequence of incidental parathyroidectomy was 15.36%, most patients with IPT (88.95%) had only one parathyroid gland removed and we found a statistically significant association (p = 0.01) between the incidence of IPT and the type of surgery. DISCUSSION: Iatrogenic injury of the parathyroid glands cause hypoparathyroidism which can be transient in majority and permanent in 1.5% of the patients. The most frequent cases with accidental removal of the parathyroid glands were total and subtotal thyroidectomies (79.6%), respectively reinterventions or completion thyroidectomies (10.62%). CONCLUSIONS: Incidental parathyroidectomy is not uncommon following thyroid surgery, even in the hands of experienced surgeons and it is more often seen in female patients with polynodular goiter according to our study. Total thyroidectomies and reinterventions on the thyroid gland increase the risk of incidental parathyroidectomy. KEY WORDS: Incidental parathyroidectomy, Hypoparathyroidism, Parathyroid glands.

Search for 22Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes.

Classical novae are thermonuclear explosions in stellar binary systems, and important sources of 26Al and 22Na. While γ rays from the decay of the former radioisotope have been observed throughout the Galaxy, 22Na remains untraceable. Its half-life (2.6 yr) would allow the observation of its 1.275 MeV γ-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of its nucleosynthesis. The 22Na(p, γ)23Mg reaction remains the only source of large uncertainty about the amount of 22Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in 23Mg. Here, we propose a combined analysis of particle-particle correlations and velocity-difference profiles to measure femtosecond nuclear lifetimes. The application of this method to the study of the 23Mg states, places strong limits on the amount of 22Na produced in novae and constrains its detectability with future space-borne observatories.

In-House Validated Map of Lymph Node Stations in a Prospective Cohort of Colorectal Cancer: A Tool for a Better Preoperative Staging.

Preoperative staging of colorectal cancer (CRC) based on imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) is crucial for identification and then removal of the positive lymph nodes (LNs). The aim of this study was to evaluate the correlation between preoperatively seen morphologic criteria (number, size, shape, structure, borders, or enhancement patterns) and histopathological features of LNs using an in-house validated map of nodal stations. A total of 112 patients with CRC that underwent surgery were preoperatively evaluated by CT scans. The locoregional, intermediate, and central LNs were CT-mapped and then removed during open laparotomy and examined under microscope. The analysis of correlations was interpreted using the suspicious-to-positive ratio (SPR) parameter. The greatest correlation was found in tumors located in the sigmoid colon, descending colon and middle rectum; SPR value was 1.12, 1.18, and 1.26, respectively. SPR proved to be 0.59 for cases of the transverse colon. Regarding the enhancement type, the dotted pattern was mostly correlated with metastatic LNs (OR: 7.84; p < 0.0001), while the homogenous pattern proved a reliable indicator of nonmetastatic LNs (OR: 1.99; p < 0.05). A total of 1809 LNs were harvested, with a median value of 15 ± 1.34 LNs/case. Transdisciplinary approach of CRC focused on pre-, intra-, and postoperatively mapping of LNs might increase the accuracy of detecting metastasized nodes for tumors of the distal colon and middle rectum but not for those of the transverse colon. In addition to morphologic criteria, the enhancement pattern of LNs can be used as a predictor of nodal involvement improving the CT-based preoperative staging.

Investigating the Prognostic Relevance of Tumor Immune Microenvironment and Immune Gene Assembly in Breast Carcinoma Subtypes.

We hypothesized that different BC subtypes are characterized by spatially distinct tumor immune microenvironment (TIME) and that immune gene assembly of metastatic (Met) and non-metastatic (Ctrl) BCs vary across subtypes. Peritumoral, stromal and intratumoral TIL was assessed on 309 BC cases. Hot, cold and immune-excluded groups were defined, and the prognostic role of this classification was assessed. CD4+/CD8+ positivity was analyzed in 75 cases in four systematically predefined tumor regions. Immune gene expression of Met and Ctrl HER2-negative BCs was compared by using NanoString nCounter technology. The amount of TIL infiltration varied greatly within all BC subtypes. Two-third of the cases were cold tumors with no significant survival difference compared to hot tumors. A lower CD4+/CD8+ ratio at the stromal internal tumor region was significantly associated with longer distant metastasis-free survival. The differentially expressed immune genes between Met and Ctrl varied across the studied BC subtypes with TNBC showing distinct features from the luminal subtypes. The TIME is characterized by a considerable heterogeneity; however, low level of TILs does not equate to disease progression. The differences in immune gene expression observed between Met and Ctrl breast carcinomas call attention to the important role of altered immune function in BC progression.

Synchronous Colorectal Cancer: Improving Accuracy of Detection and Analyzing Molecular Heterogeneity-The Main Keys for Optimal Approach.

BACKGROUND: In patients with synchronous colorectal cancer (SCRC), understanding the underlying molecular behavior of such cases is mandatory for designing individualized therapy. The aim of this paper is to highlight the importance of transdisciplinary evaluation of the pre- and post-operative assessment of patients with SCRCs, from imaging to molecular investigations. METHODS: Six patients with SCRCs presented with two carcinomas each. In addition to the microsatellite status (MSS), the epithelial mesenchymal transition was checked in each tumor using the biomarkers ß-catenin and E-cadherin, same as KRAS and BRAF mutations. RESULTS: In two of the patients, the second tumor was missed at endoscopy, but diagnosed by a subsequent computed-tomography-scan (CT-scan). From the six patients, a total of 11 adenocarcinomas (ADKs) and one squamous cell carcinoma (SCC) were analyzed. All the examined carcinomas were BRAF-wildtype microsatellite stable tumors with an epithelial histological subtype. In two of the six cases, KRAS gene status showed discordance between the two synchronous tumors, with mutations in the index tumors and wildtype status in the companion ones. CONCLUSIONS: Preoperative CT-scans can be useful for detection of synchronous tumors which may be missed by colonoscopy. Where synchronous tumors are identified, therapy should be based on the molecular profile of the indexed tumors.

Grade I, II and III Follicular Lymphomas Express Ig VH Genes with Different Patterns of Somatic Mutation.

Follicular lymphoma (FL) is an indolent, B-cell, non-Hodgkin's lymphoma with varying cytological appearance and clinical behavior. The genetic hallmark of FL is the t(14;18) translocation, and as a germinal center derived entity it is also characterized by somatic hypermutation of the immunoglobulin heavy chain (IgH) gene. In an attempt to correlate this molecular signature with the cytological grading of FL, we have analyzed the IgH variable (IgVH), regions in all cytological grades of FL. Four FL cases showing t(14;18) translocation were classified into grade I-III categories according to the current WHO guidelines. The IgVH gene segments were PCR-amplified, sequenced, and compared to their respective germline IgVH sequences. The neoplastic cells of grade I and II FLs revealed clonally related, but highly divergent IgVH gene sequences indicating the ongoing nature of somatic hypermutation. Grade III FL also showed extensive presence of somatic hypermutation, but these mutations were not associated with intraclonal divergence. Thus, these results suggest that grade I-II and grade III FL may represent different biological entities. The presence of ongoing somatic hypermutation of IgVH sequences in grade I and II FLs is compatible with direct follicular origin of these tumor cells, contrasting the homogenous, stable clones of grade III FL resembling a post-follicular stage of B-cell development. Our findings demonstrate that contrary to the three tiered cytological grading, molecular features of IgH genes classify FL into two distinct subcategories. These studies also suggest that with progression FL gains post-follicular-like molecular features and becomes independent of the germinal center microenvironment.

HER2 Heterogeneity in Gastric Cancer: A Comparative Study, Using Two Commercial Antibodies.

BACKGROUND: Although amplification of the gene encoding human epidermal growth factor receptor 2 (HER2) is used as an indicator for response to trastuzumab, the reported response rate is low, and few patients with gastric cancer (GC) benefit from this individualized therapy. The aim of this study was to examine the expression of c-erbB-2 oncoprotein (HER2), in GC samples, using two commercial immunohistochemical (IHC) antibodies, and to validate the results by checking HER2 gene amplification by fluorescence in situ hybridization (FISH). METHODS: We assessed the IHC expression of HER2 using the polyclonal antibody from Dako and CB11 clone from Leica, in 93 consecutive cases of GC samples. In all of the cases, FISH analysis was also performed using the BOND-MAX platform. RESULTS: No significant difference was observed between the two HER2 antibodies. Of the 93 cases, 22.58% demonstrated at least focal and 1+ HER2 positivity. Seven cases (7.53%) exhibited 3+ expression, and another 7 carcinomas (7.53%) were equivocal (2+). HER2 amplification was seen in 11 cases (11.83%), 10 of which were differentiated adenocarcinomas. In 5 of the cases, 2-5 sections were examined, which proved the extremely high intratumorally/intraglandular heterogeneity. FISH heterogeneity was higher in cases with only 2+ positivity on IHC assessment, compared with those showing at least one small focus of 3+ overexpression. HER2 amplification proved to be an independent negative prognostic factor. CONCLUSIONS: Due to the highly heterogeneous aspect of GC, at least 3-4 slides should be assessed by IHC, before considering a tumor to be HER2-negative. In cases with small 3+ foci representing less than 5% of tumor and in equivocal (2+) cases, FISH analysis remains the gold standard method.

Prognostic Impact of the Neutrophil-to-Lymphocyte and Lymphocyte-to-Monocyte Ratio, in Patients with Rectal Cancer: A Retrospective Study of 1052 Patients.

Despite the description of several new prognostic markers, colorectal cancer still represents the third most frequent cause of cancer-related death. As immunotherapy is considered a therapeutic alternative in such patients, neutrophil-to-lymphocyte (NLR) and lymphocyte-to-monocyte ratio (LMR) are hypothesized to provide reliable prognostic information. A retrospective study was conducted on 1052 patients operated on during 2013-2019 in two clinical hospitals from Hungary and Romania. Inclusion criteria targeted patients over 18 years old, diagnosed with rectal cancer, with preoperatively defined NLR and LMR. The overall survival rate, along with clinical and histopathological data, was evaluated. Overall survival was significantly associated with increased NLR (p = 0.03) and decreased LMR (p = 0.04), with cut-off values of 3.11 and 3.39, respectively. The two parameters were inversely correlated (p < 0.0001). There was no statistically significant association between tumor stage and NLR or LMR (p = 0.30, p = 0.06, respectively). The total mesorectal excision was especially obtained in cases with low NLR (p = 0.0005) and high LMR (p = 0.0009) values. A significant association was also seen between preoperative chemoradiotherapy and high NLR (p = 0.0001) and low LMR (p = 0.0001). In patients with rectal cancer, the preoperative values of NLR and LMR can be used as independent prognostic parameters. An NLR value of ≥3.11 can be used to indicate the response to preoperative chemoradiotherapy, but a low chance of sphincter preservation or obtaining a complete TME. Higher values of NLR and lower values of LMR require a more attentive preoperative evaluation of the mesorectum.

Cystic low-grade collecting duct renal carcinoma with liver compression - A challenging diagnosis and therapy: A case report.

BACKGROUND: A collecting duct carcinoma is a very rare, malignant renal epithelial tumor. Distant metastases are present in one third of cases at the time of diagnosis. It is known to have a poor prognosis. CASE SUMMARY: A 42-year-old male was sent to our surgery clinic for removal of a 119.2 mm × 108.3 mm encapsulated cystic mass, which was localized in the 8th segment of the right liver lobe. The lesion was first identified on ultrasonography. A computed tomography scan confirmed the presence of a Bosniak type III cystic lesion, which affected the liver and convexity of the right kidney. Surgical intervention involved a right nephrectomy, with removal of the cystic mass. The patient was mobilized on the first postoperative day and was discharged after 7 d. The histological and immunohistochemical examination revealed a low-grade collecting duct renal carcinoma, which is a rare variant of papillary carcinoma, with low malignant potential. The patient did not receive chemotherapy and after 21 mo of follow-up, a radiological examination and laboratory analyses showed normal aspects. No relapse or other complications were reported. CONCLUSION: To manage renal tumors properly, a correct histopathological diagnosis is crucial, as is early diagnosis and correct surgical treatment.

[Application of computed tomography and abdominal pressure measurement in the treatment of giant incisional hernias]. / Számítógépes tomográfia és hasurinyomás-mérés alkalmazása az óriás medián hegsérvek kezelésében.

Introduction: Giant abdominal wall defects represent a major challenge for surgeons. CT scan can determine the ratio between the volume of the hernia sac and the abdominal cavity, determining the extent of the disproportion, which is related to the postoperative abdominal pressure value. Aim: Confirmation of the significance of CT examination in postoperative giant abdominal wall defects, effectiveness analysis of the reconstruction method by abdominal pressure measurement. Method: A prospective study is conducted on patients with giant incisional hernias, with preoperatively performed abdominal CT scan. Tension-free abdominal wall reconstruction is realized with retromuscular Prolene mesh and hernial sac. Abdominal pressure is measured during and after surgery. Patients' follow-up is performed through phone after 2-4-6 months. Results: We present our results through three cases. First case: 48-year-old woman presented a giant recurrent incisional hernia and multiple comorbidities. Maximum defect diameter was: 155 mm, hernia volume: 1536.63 cm3, BMI = 43.6. The patient was discharged after seven days. Second case: 51-year-old male patient presented with multilocular giant incisional hernia, BMI = 26,85. Maximum diameter of the two wall defects were 123 mm and 105 mm, their total volume: 406.41cm3. The patient was discharged after five days. Third case: A 67-year-old male patient presented with giant incisional hernia. The abdominal defect size was 100/100 mm (LL/CC), volume: 258.10 cm3, BMI = 23.7. The patient was discharged after four days. Conclusion: The proper surgical technique can be established based on the preoperative CT scan. Abdominal wall reconstruction with retromuscular Prolene mesh and hernial sac provides a cheap, reliable, tension-free technique. The technique's short-term efficacy can be determined by abdominal pressure measuring through the bladder. Orv Hetil. 2020; 161(9): 347-353.

Immunohistochemical-based molecular subtyping of colorectal carcinoma using maspin and markers of epithelial-mesenchymal transition.

The aim of the present study was to classify colorectal carcinoma (CRC) into molecular subtypes, based on immunohistochemical (IHC) assessments. A total of 112 CRC samples were molecularly classified based on the expression levels of epithelial-mesenchymal transition (EMT)-associated IHC markers. A total of three molecular subtypes were defined: Epithelial, membrane positivity for E-cadherin and ß-catenin, negative for vimentin; mesenchymal, E-cadherin-negative, nuclear ß-catenin- and vimentin-positive; and hybrid cases, epithelial tumor core and mesenchymal tumor buds. Most of the cases were diagnosed as moderately differentiated adenocarcinoma (n=89; 79.46%). The majority of cases (n=100; 89.28%) exhibited a mismatch repair proficient status (microsatellite stable CRCs). A predominance of epithelial-type (n=51; 45.54%) and hybrid CRCs (n=47; 41.96%) was observed, whereas a few cases (n=14; 12.50%) were classified as mesenchymal-type CRCs. This molecular classification was associated with pathological stage (P<0.01), pT stage (P=0.04), pN stage (P<0.01), the grade of tumor budding (P=0.04), and maspin expression in both the tumor core (P=0.04) and the invasion front (P<0.01). The mesenchymal-type cases predominantly exhibited lymph node metastases, high-grade budding and a tendency towards maspin nuclear predominance. All epithelial-type cases with maspin-only expression (n=18) were non-metastatic. Patients with CRC of the epithelial subtype and those with a lymph node ratio (LNR) ≤0.15 presented the best overall survival, followed by those with hybrid and mesenchymal subtypes. Nuclear maspin positivity was more frequent in cases with a high-budding degree compared with those with a low-budding degree (P=0.03). The EMT-associated molecular classification of CRCs may be used to identify the most aggressive CRCs, which show a mesenchymal phenotype, high-budding degree, maspin nuclear positivity and lymph node metastases. The pN stage, LNR and budding degree of patients, which can be evaluated with maspin expression, remain the most important prognostic factors.

Lymph node ratio, an independent prognostic factor for patients with stage II-III rectal carcinoma.

BACKGROUND: Identification of the proper surgical method and the most reliable prognostic parameters of rectal carcinomas is a challenging issue. The aim of this paper was to determine the possible prognostic role of the number of harvested lymph nodes versus lymph node ratio (LNR) in patients with rectal carcinomas, and the proper value of LNR that can be used as prognostic parameter. MATERIALS AND METHODS: A retrospective study was performed in 186 consecutive patients with rectal carcinomas that underwent surgical resection. The LNR was calculated for cases from stage II-III, and was correlated with classic prognostic parameters and overall survival (OS). RESULTS: A statistically significant difference was found between LNR of 0.15 and OS (p = 0.03), respectively LNR > 0.15 and TNM stage (p < 0.0001), but also tumor infiltration level (p < 0.05). The number of harvested lymph nodes was not correlated with the tumor stage (r = 0.148, p = 0.06) and this parameter did not influence the OS, when the number of 12 or 14 lymph nodes was used as the ideal value (p = 0.6 and p = 0.66, respectively). CONCLUSION: In patients with rectal carcinomas that underwent preoperative chemoradiotherapy, a LNR of 0.15 is a parameter with independent prognostic value, comparing with the number of harvested lymph nodes. The specific LNR should be calculated in larger cohorts.

DNA lesions and repair in immunoglobulin class switch recombination and somatic hypermutation.

Immunoglobulin (Ig) gene somatic hypermutation (SHM) and class switch DNA recombination (CSR) are critical for the maturation of the antibody response. These processes endow antibodies with increased antigen-binding affinity and acquisition of new biological effector functions, thereby underlying the generation of memory B cells and plasma cells. They are dependent on the generation of specific DNA lesions and the intervention of activation-induced cytidine deaminase as well as newly identified translesion DNA polymerases, which are expressed in germinal center B cells. DNA lesions include mismatches, abasic sites, nicks, single-strand breaks, and double-strand breaks (DSBs). DSBs in the switch (S) region DNA are critical for CSR, but they also occur in V(D)J regions and possibly contribute to the events that lead to SHM. The nature of the DSBs in the Ig locus, their generation, and the repair processes that they trigger and that are responsible for their regulation remain poorly understood. Aberrant regulation of these events can result in chromosomal breaks and translocations, which are significant steps in B-cell neoplastic transformation.

Microsatellite analysis of primary and recurrent glial tumors suggests different modalities of clonal evolution of tumor cells.

Gliomas are characterized by highly variable biological behavior. After surgical resection and postoperative therapy they frequently recur with the same or higher-grade histology. Although a number of genetic aberrations have been described in gliomas of different histological types, the molecular mechanisms of the histological and clinical progression are poorly understood. In this study, we performed longitudinal microsatellite and mismatch repair gene analysis in paired samples of primary and recurrent gliomas in order to reveal whether genetic instability is associated with tumor progression. The 7 microsatellite loci of the 7 patients displayed a total of 18 (54.5%) alterations in the primary and 15 (45.5%) alterations in the recurrent gliomas as compared with the corresponding non-neoplastic cells, but no alterations were found in the hMLH1 and hMSH2 genes. These results suggest that microsatellite instability is associated with the development of the primary gliomas rather than with the recurrence or progression, and it is not associated with structural alterations in the hMLH1 or hMSH2 genes. Comparison of the microsatellite patterns in primary and secondary gliomas revealed 4 different modalities of clonal evolution, involving clonal identity, clonal deletion, clonal progression, and different clonality, suggesting that intensive clonal selection may play a central part in the recurrence of gliomas.

Mutational analysis of IgVH and BCL-6 genes suggests thymic B-cells origin of mediastinal (thymic) B-cell lymphoma.

Mediastinal (thymic) large B-cell lymphoma (MBL) has been defined as a subtype of diffuse large B-cell lymphoma (DLBL) arising in the mediastinum with characteristic clinicopathological features. It has been postulated that MBL arise from non-circulating thymic B-cells and represent a distinct lymphoma entity, however, the histogenesis of the disease is not yet fully understood. In order to clarify the histogenetic derivation of MBL and to determine the relationship of MBL to thymic B-cells we have analyzed the nucleic acid sequences of immunoglobulin (Ig) heavy chain variable region (VH) and 5' noncoding region of BCL-6 genes in normal thymic B-cells and six cases of MBL. Thymic B-cells and tumor cells of MBLs displayed hypermutated VH and/or BCL-6 genes but intraclonal divergence did not associate with these mutations. Since somatic mutations of the IgVH and BCL-6 genes are histogenetic markers of B-cell transit through the germinal centre (GC), these results suggest that both thymic B-cells and MBLs derived from GC or an equivalent environment where B-cells underwent somatic hypermutation. The similar pattern of mutations of IgVH and BCL-6 genes found in thymic B-cells and MBLs further supports the theory that MBLs originate from thymic B-cells.

14-3-3 adaptor proteins recruit AID to 5'-AGCT-3'-rich switch regions for class switch recombination.

Class switch DNA recombination (CSR) is the mechanism that diversifies the biological effector functions of antibodies. Activation-induced cytidine deaminase (AID), a key protein in CSR, targets immunoglobulin H (IgH) switch regions, which contain 5'-AGCT-3' repeats in their core. How AID is recruited to switch regions remains unclear. Here we show that 14-3-3 adaptor proteins have an important role in CSR. 14-3-3 proteins specifically bound 5'-AGCT-3' repeats, were upregulated in B cells undergoing CSR and were recruited with AID to the switch regions that are involved in CSR events (Smu-->Sgamma1, Smu-->Sgamma3 or Smu-->Salpha). Moreover, blocking 14-3-3 by difopein, 14-3-3gamma deficiency or expression of a dominant-negative 14-3-3sigma mutant impaired recruitment of AID to switch regions and decreased CSR. Finally, 14-3-3 proteins interacted directly with AID and enhanced AID-mediated in vitro DNA deamination, further emphasizing the important role of these adaptors in CSR.