ECM1 and KRT6A are involved in tumor progression and chemoresistance in the effect of dexamethasone on pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) has a very poor prognosis. Neoadjuvant chemotherapy is an effective PDAC treatment option, but chemotherapy causes unfavorable side effects. Glucocorticoids (e.g., dexamethasone [DEX]) are administered to reduce side effects of chemotherapy for solid tumors, including pancreatic cancer. Glucocorticoids have both beneficial and detrimental effects, however. We investigated the functional changes and gene-expression profile alterations induced by DEX in PDAC cells. PDAC cells were treated with DEX, and the cell proliferation, migration, invasion, and chemosensitivity to gemcitabine (GEM) were evaluated. The results demonstrated decreased cell proliferative capacity, increased cell migration and invasion, and decreased sensitivity to GEM. A comprehensive genetic analysis revealed marked increases in ECM1 and KRT6A in DEX-treated PDAC cells. We evaluated the effects of ECM1 and KRT6A expression by using PDAC cells transfected with those genes. Neither ECM1 nor KRT6A changed the cells' proliferation, but each enhanced cell migration and invasion. ECM1 decreased sensitivity to GEM. We also assessed the clinicopathological significance of the expressions of ECM1 and KRT6A in 130 cases of PDAC. An immunohistochemical analysis showed that KRT6A expression dominated the poorly differentiated areas. High expressions of these two proteins in PDAC were associated with a poorer prognosis. Our results thus demonstrated that DEX treatment changed PDAC cells' functions, resulting in decreased cell proliferation, increased cell migration and invasion, and decreased sensitivity to GEM. The molecular mechanisms of these changes involve ECM1 and KRT6A, whose expressions are induced by DEX.

Dynamic diversity of SARS-CoV-2 genetic mutations in a lung transplantation patient with persistent COVID-19.

Numerous SARS-CoV-2 variant strains with altered characteristics have emerged since the onset of the COVID-19 pandemic. Remdesivir (RDV), a ribonucleotide analogue inhibitor of viral RNA polymerase, has become a valuable therapeutic agent. However, immunosuppressed hosts may respond inadequately to RDV and develop chronic persistent infections. A patient with respiratory failure caused by interstitial pneumonia, who had undergone transplantation of the left lung, developed COVID-19 caused by Omicron BA.5 strain with persistent chronic viral shedding, showing viral fusogenicity. Genome-wide sequencing analyses revealed the occurrence of several viral mutations after RDV treatment, followed by dynamic changes in the viral populations. The C799F mutation in nsp12 was found to play a pivotal role in conferring RDV resistance, preventing RDV-triphosphate from entering the active site of RNA-dependent RNA polymerase. The occurrence of diverse mutations is a characteristic of SARS-CoV-2, which mutates frequently. Herein, we describe the clinical case of an immunosuppressed host in whom inadequate treatment resulted in highly diverse SARS-CoV-2 mutations that threatened the patient's health due to the development of drug-resistant variants.

Derivatization procedure of estradiol with a combination of MPDNP-F and 4-dimethylaminopyridine to generate product ion containing estradiol-skeleton for reliable determination of its serum/plasma concentrations by LC/ESI-MS/MS.

The quantification of serum/plasma estradiol (E2) is useful for the diagnosis, pathological analysis, and monitoring of the therapeutic efficacy of estrogen-dependent diseases. In this study, an improved derivatization method using 1-(2,4-dinitro-5-fluorophenyl)-4,4-dimethylpiperazinium iodide (MPDNP-F) was developed and combined with liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) for the sensitive and specific quantification of the serum/plasma E2. In the new method, the reaction time was reduced to 15 min from 90 min (two-step reaction in the previous method) by the direct reaction of MPDNP-F with E2 at 60°C in the presence of 4-dimethylaminopyridine (DMAP). DMAP served as the organic catalyst and had a less negative effect on the LC/ESI-MS/MS instrument compared to the non-volatile inorganic salt (NaHCO3), which was used in the previous method. The collision-induced dissociation of the molecular cation ([M]+) of the resulting derivative provided a product ion containing the E2-skeleton ([M-NO2-H]+), which significantly enhanced the assay sensitivity and specificity; compared to the dansyl chloride derivatization, which is the currently most-used derivatization procedure for the LC/ESI-MS/MS assays of E2, the MPDNP-F derivatization had significantly fewer interfering peaks and a clear and flat baseline in the serum sample analysis. The MPDNP-F derivatization-LC/ESI-MS/MS method enabled the precise and accurate quantification of E2 even at a 5.0 pg/mL concentration (lower limit of quantification) with a small sample volume (100 µL of serum/plasma) and had a tolerance for the matrix effect. This method was also proven to serve as a more sensitive and specific alternative to the clinically used chemiluminescence enzyme immunoassay.

The impact of PIK3CA mutations and PTEN expression on the effect of neoadjuvant therapy for postmenopausal luminal breast cancer patients.

BACKGROUND: There is pressing needs to find the biomarker in the selection of neoadjuvant therapy in postmenopausal luminal breast cancer patients. We examined the hypothesis that PIK3CA mutations and low phosphatase and tensin homolog (PTEN) expression affect the response to neoadjuvant therapy and prognosis in postmenopausal luminal breast cancer patients. METHODS: Postmenopausal patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative breast cancer, up to stage II, who underwent neoadjuvant chemotherapy (NAC; n = 60) or neoadjuvant endocrine therapy (NAE; n = 55) were selected. PIK3CA exon 9 and exon 20 mutations were screened by high resolution melting analysis and confirmed by Sanger sequence. PTEN expression was evaluated by immunohistochemistry. The relationships among PIK3CA mutations, PTEN expression, clinicopathological features, the pathological effect of neoadjuvant therapy, recurrence-free survival (RFS) and overall survival were analyzed. RESULTS: Among 115 patients, PIK3CA mutations and low PTEN expression before treatment were detected in 35 patients (30.4%) and in 28 patients (24.3%), respectively. In the NAC group, tumor with PIK3CA mutations showed significantly poorer response than tumor with PIK3CA wild-type (p = 0.03). On the other hand, in the NAE group, there was no significant difference in pathological therapeutic effect between tumor with PIK3CA mutations and tumor with PIK3CA wild-type (p = 0.54). In the NAC group, the log-rank test showed no difference in RFS between patients with PIK3CA mutations and PIK3CA wild-type (p = 0.43), but patients with low PTEN expression showed significantly worse RFS compared to patients with high PTEN expression (5 year RFS 0.64 vs. 0.87, p = 0.01). In the Cox proportional hazards model for RFS, PTEN expression, progesterone receptor, and pathological therapeutic effect were predictive factors for time to recurrence (All p < 0.05). CONCLUSIONS: PIK3CA mutations are associated with resistance to NAC but do not affect the response to NAE. Low PTEN expression does not affect response to either NAC or NAE but correlates with shorter RFS in patients who received NAC. These biomarkers will be further evaluated for clinical use to treat postmenopausal luminal breast cancer patients.

Precision cancer genome testing needs proficiency testing involving all stakeholders.

To implement precision oncology, analytical validity as well as clinical validity and utility are important. However, proficiency testing (PT) to assess validity has not yet been systematically performed in Japan. To investigate the quality of next-generation sequencing (NGS) platforms and cancer genome testing prevalent in laboratories, we performed pilot PT using patient samples. We prepared genomic DNA from the cancer tissue and peripheral blood of 5 cancer patients and distributed these to 15 laboratories. Most participating laboratories successfully identified the pathogenic variants, except for two closely located KRAS variants and 25 bp delins in EGFR. Conversely, the EGFR L858R variant was successfully identified, and the allele frequency was similar for all the laboratories. A high DNA integrity number led to excellent depth and reliable NGS results. By conducting this pilot study using patient samples, we were able to obtain a glimpse of the current status of cancer genome testing at participating laboratories. To enhance domestic cancer genome testing, it is important to conduct local PT and to involve the parties concerned as organizers and participants.

Prediction of mismatch repair deficient biliary tract cancer: Role of morphological features and host immune response detected by routine hematoxylin-eosin staining.

BACKGROUND/PURPOSE: The objective of this study was to determine the frequency and predictors of biliary tract cancer (BTC) with deficient DNA mismatch repair (dMMR) in Japan. METHODS: Immunostaining and microsatellite instability analysis were performed for mismatch repair-related proteins in tissue specimens from 662 patients who underwent surgery for BTC between 2001 and 2017 to identify dMMR-BTC. We compared dMMR-BTC and proficient MMR (pMMR)-BTC based on patient demographics, pathological features, and host immune responses characterized by the percentage of stromal tumor infiltrating lymphocytes (sTIL percentage) and tertiary lymphoid structures (TLS). RESULTS: The incidence of dMMR-BTC was 2.3%. Significant predictors of dMMR-BTC were its primary lesion being intrahepatic cholangiocarcinoma (odds ratio [OR] 6.34, P = .004), presence of signet ring cell component (OR 35.62, P < .001), sTIL percentage ≥40% (OR 3.43, P = .038), and presence of TLS (OR 22.22, P < .001). The sensitivity, specificity, and negative likelihood ratio for any one or more of these four variables to be positive were 93.3%, 57.8%, and 0.12, respectively. CONCLUSION: Evaluation of histopathological findings and host immune response based on conventional histochemical staining is useful for efficient and inexpensive diagnostic screening of dMMR-BTC patients.

Usefulness of the MALDI-TOF MS technology with membrane filter protocol for the rapid identification of microorganisms in perioperative drainage fluids of hepatobiliary pancreatic surgery.

Surgical site infections (SSIs) are significant and frequent perioperative complications, occurring due to the contamination of the surgical site. The late detection of SSIs, especially organ/space SSIs which are the more difficult to treat, often leads to severe complications. An effective method that can identify bacteria with a high accuracy, leading to the early detection of organ/space SSIs, is needed. Ninety-eight drainage fluid samples obtained from 22 patients with hepatobiliary pancreatic disease were analyzed to identify microorganisms using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) with a new membrane filtration protocol and rapid BACpro® pretreatment compared to sole rapid BACpro® pretreatment. The levels of detail of rapid BACpro® pretreatment with or without filtration were also evaluated for the accuracy of bacterial identification. We found that reliable scores for E. coli and E. faecalis were obtained by inoculation with 1.0 × 104 CFU/ml after preparation of the membrane filter with rapid BACpro®, indicating approximately 10-folds more sensitive compared to sole rapid BACpro® pretreatment in drainage fluid specimens. Among 60 bacterial positive colonies in drainage fluid specimens, the MALDI-TOF MS and the membrane filtration with rapid BACpro® identified 53 isolates (88.3%) with a significantly higher accuracy, compared to 25 isolates in the rapid BACpro® pretreatment group (41.7%) (p < 0.001). Among the 78 strains, 14 enteric Gram-negative bacteria (93.0%) and 55 Gram-positive cocci (87.3%) were correctly identified by the membrane filtration with rapid BACpro® with a high reliability. This novel protocol could identify bacterial species within 30 min, at $2-$3 per sample, thus leading to cost and time savings. MALDI-TOF MS with membrane filter and rapid BACpro® is a quick and reliable method for bacterial identification in drainage fluids. The shortened analysis time will enable earlier selection of suitable antibiotics for treatment of organ/space SSIs to improve patients' outcomes.

Anti-FIRΔexon2 autoantibody as a novel indicator for better overall survival in gastric cancer.

There is no clinically available biomarker for efficiently indicating the overall survival or therapy response of gastric cancer (GC). The autoantibodies (Abs) in the sera of anti-far-upstream element-binding protein-interacting repressor-lacking exon2 (FIRΔexon2), anti-sorting nexin 15, and anti-spermatogenesis and oogenesis-specific basic helix-loop-helix 1 were markedly higher in GC patients than in healthy donors (HDs). These Abs were identified by large-scale serological identification of antigens by recombinant cDNA expression cloning screenings and their expression levels were evaluated by amplified luminescence proximity homogeneous assay. In particular, compared with age-matched HDs, the level of anti-FIRΔexon2 Abs in GC patients was significantly higher (P < .001). The Spearman's rank correlation analysis between anti-FIRΔexon2 Abs and clinically available tumor markers such as carcinoembryonic antigen (CEA) was statistically insignificant, indicating that FIRΔexon2 Abs is an independent biomarker. We performed receiver-operating curve analysis to evaluate the anti-FIRΔexon2 Ab as a candidate biomarker with CEA and carbohydrate antigen 19-9 (CA19-9). The overall survival of GC patients with high anti-FIRΔexon2 Abs titer was significantly favorable (P = .04) than that of GC patients who were below detection level of anti-FIRΔexon2 Abs. However, clinical stages were not apparently correlated with the levels of anti-FIRΔexon2 Ab, CEA, and CA19-9. In conclusion, anti-FIRΔexon2 Abs detected in GC patients is a potential biomarker for monitoring a better prognosis. Hence, anti-FIRΔexon2 Abs is a promising biomarker for indicating better overall survival of gastric cancer patients.

Anti-FIRΔexon2, a splicing variant form of PUF60, autoantibody is detected in the sera of esophageal squamous cell carcinoma.

Anti-PUF60 autoantibodies are reportedly detected in the sera of patients with dermatomyositis and Sjögren's syndrome; however, little is known regarding its existence in the sera of cancer patients. FIR, a splicing variant of the PUF60 gene, is a transcriptional repressor of c-myc. In colorectal cancer, there is an overexpression of the dominant negative form of FIR, in which exon 2 is lacking (FIRΔexon2). Previously, large-scale SEREX (serological identification of antigens by recombinant cDNA expression cloning) screenings have identified anti-FIR autoantibodies in the sera of cancer patients. In the present study, we revealed the presence and significance of anti-FIR (FIR/FIRΔexon2) Abs in the sera of patients with esophageal squamous cell carcinoma (ESCC). Our results were validated by an amplified luminescence proximity homogeneous assay using sera of patients with various cancer types. We revealed that anti-FIRΔexon2 Ab had higher sensitivity than anti-FIR Ab. Receiver operating characteristic (ROC) analysis was applied for evaluating the use of anti-FIRΔexon2 Ab as candidate markers such as anti-p53 Ab and carcinoembryonic antigen, and the highest area under the ROC curve was observed in the combination of anti-FIRΔexon2 Ab and anti-p53 Ab. In summary, our results suggest the use of anti-FIRΔexon2 Ab in combination with the anti-p53 Ab as a predictive marker for ESCC. The area under the ROC curve was further increased in the advanced stage of ESCC. The value of anti-FIRΔexon2 autoantibody as novel clinical indicator against ESCC and as a companion diagnostic tool is discussed.

Use of the MALDI BioTyper system and rapid BACpro with MALDI-TOF MS for rapid identification of microorganisms causing bacterial urinary tract infection in feline urine samples.

With the increasing number of cats kept as pets, opportunities to treat cats with lower urinary tract disease (LUTD) have recently increased in the clinical veterinary field. Urine samples collected from 50 cats with bacterial cystitis brought to Maeda Veterinary Hospital between August 10, 2015 and March 31, 2017 were used in the study. Sample preparation of the urine was performed using a MALDI Sepsityper kit and rapid BACpro. To identify the isolates, MALDI-TOF MS was performed on an AutoFlex TOF/TOF mass spectrometer. MALDI-TOF MS using rapid BACpro for pretreatment was found to be a quick and reliable method for identification of bacteria from infected urine, with a shortened analysis time enabling earlier and more accurate selection of antibiotics for treatment of feline LUTD.

Molecular Nodal Staging Using miRNA Expression in Lung Cancer Patients by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration.

BACKGROUND: The limited negative predictive value of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has often been discussed. OBJECTIVE: The aim of this study was to identify a highly sensitive molecular biomarker for lymph node staging by EBUS-TBNA. METHODS: Five microRNAs (miRNAs) (miR-200a, miR-200b, miR-200c, miR-141, and let-7e) were selected as biomarker candidates for the detection of nodal metastasis in a miRNA expression analysis. After having established a cutoff level of expression for each marker to differentiate malignant from benign lymph nodes among surgically dissected lymph nodes, the cutoff level was applied to snap-frozen EBUS-TBNA samples. Archived formalin-fixed paraffin- embedded (FFPE) samples rebiopsied by EBUS-TBNA after induction chemoradiotherapy were also analyzed. RESULTS: The expression of all candidate miRNAs was significantly higher in metastatic lymph nodes than in benign ones (p < 0.05) among the surgical samples. miR-200c showed the highest diagnostic yield, with a sensitivity of 95.4% and a specificity of 100%. When the cutoff value for miR-200c was applied to the snap-frozen EBUS-TBNA samples, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 97.4, 81.8, 95.0, 90.0, and 94.0%, respectively. For restaging FFPE EBUS- TBNA samples, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 100, 60.0, 80.0, 100, and 84.6%, respectively. Among the restaged samples, 4 malignant lymph nodes were false negative by EBUS-TBNA, but they were accurately identified by miR-200c. CONCLUSIONS: miR-200c can be used as a highly sensitive molecular staging biomarker that will enhance nodal staging of lung cancer.

Locked Nucleic Acid Technology for Highly Sensitive Detection of Somatic Mutations in Cancer.

The molecular diagnosis of the cancer mutational status is essential for modern clinical laboratory medicine. Mutations in EGFR, KRAS, BRAF, and PIK3CA genes are widely analyzed in solid tumors such as lung cancer, colorectal cancer, breast cancer, and melanoma. The allele-specific polymerase chain reaction, high-resolution melting, and Sanger sequencing are used for detecting and identifying gene mutations in many clinical laboratories. The locked nucleic acid (LNA) is a class of nucleic acid analogs that contain a methylene bridge connecting the 2' oxygen and 4' carbon in the ribose moiety. This methylene bridge locks the ribose group into a C3'-endo conformation. LNA, including an oligonucleotide, increases the thermal stability of hybrid strands. The use of LNA technology in molecular diagnostic methods improves the specificity and sensitivity of assays. This review describes routinely analyzed mutations and molecular diagnostic methods used in the clinical laboratory along with the performance improvement of mutational analysis with LNA.

Assessment by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry of the Effects of Preanalytical Variables on Serum Peptidome Profiles Following Long-Term Sample Storage.

PURPOSE: Human serum and plasma are often used as clinical specimens in proteomics analyses, and peptidome profiling of human serum is a promising tool for identifying novel disease-associated biomarkers. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used for peptidomic biomarker discovery. Careful sample collection and handling are required as either can have a profound impact on serum peptidome patterns, yet the effects of preanalytical variables on serum peptidome profiles have not been completely elucidated. The present study investigated the effects of preanalytical variables, including storage temperature, duration (up to 12 months), and thawing methods, on MALDI-TOF MS-based serum peptidome patterns. EXPERIMENTAL DESIGN: Aliquots of serum samples were pretreated with weak cation exchanger magnetic beads using an automated ClinProtRobot system and then analyzed by MALDI-TOF MS. RESULTS: A number of significant differences in peak intensities were observed depending on sample processing variables. CONCLUSIONS AND CLINICAL RELEVANCE: These peaks can be used as sample quality markers to assess the effects of long-term storage on serum peptidome profiles using MALDI-TOF MS.

Locked nucleic acid probe enhances Sanger sequencing sensitivity and improves diagnostic accuracy of high-resolution melting-based KRAS mutational analysis.

BACKGROUND: Sanger sequencing is the gold standard for mutational analysis and widely used after high resolution melting (HRM) screening. However, the sensitivity of this method may be insufficient for identifying low frequency mutations. Therefore, for accurate diagnosis, enhanced sensitivity is warranted. METHODS: We designed a wild-type blocking cycle sequencing method using locked nucleic acid (LNA) probe (LNA-Sanger sequencing) for codons 12 and 13 of KRAS exon 2. We analyzed the sensitivities of HRM, conventional Sanger sequencing, and LNA-Sanger sequencing of formalin-fixed paraffin-embedded (FFPE) reference standard samples with low frequency (5%) mutations in codons 12 and 13. RESULTS: Use of LNA probe significantly improved the sensitivity of Sanger sequencing (p=0.0003). Sensitivities of KRAS mutation tests were as follows: HRM, 5%; conventional Sanger sequencing, 10%; and LNA-Sanger sequencing, 5%. FFPE samples with 5% mutation were accurately diagnosed by LNA-Sanger sequencing, whereas it was difficult to identify the mutations by conventional Sanger sequencing. CONCLUSIONS: LNA-Sanger sequencing is a facile technique for the enrichment of mutant alleles and useful for the accurate diagnosis of HRM-positive cases with low frequency mutations.

Combined Secretomics and Transcriptomics Revealed Cancer-Derived GDF15 is Involved in Diffuse-Type Gastric Cancer Progression and Fibroblast Activation.

Gastric cancer is classified into two subtypes, diffuse and intestinal. The diffuse-type gastric cancer (DGC) has poorer prognosis, and the molecular pathology is not yet fully understood. The purpose of this study was to identify functional secreted molecules involved in DGC progression. We integrated the secretomics of six gastric cancer cell lines and gene expression analysis of gastric cancer tissues with publicly available microarray data. Hierarchical clustering revealed characteristic gene expression differences between diffuse- and intestinal-types. GDF15 was selected as a functional secreted molecule owing to high expression only in fetal tissues. Protein expression of GDF15 was higher in DGC cell lines and tissues. Serum levels of GDF15 were significant higher in DGC patients as compared with healthy individuals and chronic gastritis patients, and positively correlated with wall invasion and lymph node metastasis. In addition, the stimulation of GDF15 on NIH3T3 fibroblast enhanced proliferation and up-regulated expression of extracellular matrix genes, which were similar to TGF-ß stimulation. These results indicate that GDF15 contributes to fibroblast activation. In conclusion, this study revealed that GDF15 may be a novel functional secreted molecule for DGC progression, possibly having important roles for cancer progression via the affecting fibroblast function, as well as TGF-ß.

[Assessment of Vitamin D Metabolism by LC-MS/MS].

Vitamin D is pro-hormone that has important roles in calcium metabolism in the intestine, kidneys, and bone. Many studies have indicated that vitamin D deficiency causes not only rickets and osteomalacia, but also increases the risk of various diseases such as cancer and autoimmune disease. Of the many vitamin D metabolites, 25-hydroxyvitamin D[25OH-D], 1α,25-dihydroxyvitamin D[1,25(OH)2-D], and 24,25-dihydroxyvitamin D [24,25 (OH) 2-D] are important for assessing vitamin D metabolism. They are circulating, biologically active, and major inactive forms of vitamin D metabolite, respectively. Immunoassays are widely used for the measurement of serum/plasma vitamin D metabolites. With such an assay, however, the accurate quantification of these metabolites is difficult because of cross-reactivity. Liquid chromatography-tandem mass spectrometry [LC-MS/MS] is the gold standard method for analyzing these metabolites due to its high sensitivity and selectivity. Derivatization with a Cookson-type reagent is a key technique for robust and sensitive analysis by LC-MS/MS. A Cookson-type reagent rapidly and quantitatively reacts with the s-cis-diene structure of vitamin D metabolites, and markedly enhances the ionization efficiency. Using a recently developed Cookson-type reagent (DAPTAD), we successfully established an LC-MS/MS-based method for analyzing serum vitamin D metabolites including 250H-D, 1,25 (OH) 2-D, and 24,25 (OH) 2-D. Thus, LC-MS/MS can be a powerful tool for the accurate determination of vitamin D metabolism. In this review, we describe the advantages of LC-MS/MS for the determination of vitamin D metabolites.

Haploinsufficiency of the c-myc transcriptional repressor FIR, as a dominant negative-alternative splicing model, promoted p53-dependent T-cell acute lymphoblastic leukemia progression by activating Notch1.

FUSE-binding protein (FBP)-interacting repressor (FIR) is a c-myc transcriptional suppressor. A splice variant of FIR that lacks exon 2 in the transcriptional repressor domain (FIRΔexon2) upregulates c-myc transcription by inactivating wild-type FIR. The ratio of FIRΔexon2/FIR mRNA was increased in human colorectal cancer and hepatocellular carcinoma tissues. Because FIRΔexon2 is considered to be a dominant negative regulator of FIR, FIR heterozygous knockout (FIR⁺/⁻) C57BL6 mice were generated. FIR complete knockout (FIR⁻/⁻) was embryonic lethal before E9.5; therefore, it is essential for embryogenesis. This strongly suggests that insufficiency of FIR is crucial for carcinogenesis. FIR⁺/⁻ mice exhibited prominent c-myc mRNA upregulation, particularly in the peripheral blood (PB), without any significant pathogenic phenotype. Furthermore, elevated FIRΔexon2/FIR mRNA expression was detected in human leukemia samples and cell lines. Because the single knockout of TP53 generates thymic lymphoma, FIR⁺/⁻TP53⁻/⁻ generated T-cell type acute lymphocytic/lymphoblastic leukemia (T-ALL) with increased organ or bone marrow invasion with poor prognosis. RNA-sequencing analysis of sorted thymic lymphoma cells revealed that the Notch signaling pathway was activated significantly in FIR⁺/⁻TP53⁻/⁻ compared with that in FIR⁺/⁺TP53⁻/⁻ mice. Notch1 mRNA expression in sorted thymic lymphoma cells was confirmed using qRT-PCR. In addition, flow cytometry revealed that c-myc mRNA was negatively correlated with FIR but positively correlated with Notch1 in sorted T-ALL/thymic lymphoma cells. Moreover, the knockdown of TP53 or c-myc using siRNA decreased Notch1 expression in cancer cells. In addition, an adenovirus vector encoding FIRΔexon2 cDNA increased bleomycin-induced DNA damage. Taken together, these data suggest that the altered expression of FIRΔexon2 increased Notch1 at least partially by activating c-Myc via a TP53-independent pathway. In conclusion, the alternative splicing of FIR, which generates FIRΔexon2, may contribute to both colorectal carcinogenesis and leukemogenesis.

[Alternative Splicing Detection as a Biomarker for Cancer Diagnosis: A Novel Progressive Mechanism of Acute Lymphoblastic Leukemia with Alternative Splicing as a Biomarker Candidate].

Alternative splicing is an important mechanism that links to transcription and contributes to protein diversity. Disturbed alternative splicing is frequently observed in cancers, but its precise mechanism remains largely unknown. FUSE-binding protein (FBP) -interacting repressor (FIR) is a transcriptional repressor of the c-myc gene. Previous studies indicated that a splice variant of FIR, FIRΔexon2, that lacks exon2 in the transcriptional repressor domain, was increased in colorectal cancers, hepatocellular carcinomas, and leukemia cells. Furthermore, FIRΔexon2 activated c-myc transcription by disabling wild-type FIR as a dominant-negative form of FIR. Recently, somatic mutations of the SF3B1 (SAP155) gene, a subunit of the SF3B spliceosome complex, were found in myelodysplastic leukemia. In this study, FIR heterozygous knockout (FIR(+/-)) was established as a dominant-negative model of FIR in the C57BL/6 mouse. FIR(+/-) mice showed an increased c-myc mRNA expression level, particularly in peripheral blood, although FIR(+/-) mice had no apparent pathogenic phenotype. Therefore, an increased c-myc mRNA expression level alone is not enough for leukemogenesis. Nevertheless, FIR(+/-)TP53(-/-) mice generated acute T-cell lymphoblastic leukemia (T-ALL) with increased organ and/or bone marrow invasion. In conclusion, alternative splicing of FIR, generating FIRΔexon2, contributes to not only colorectal carcinogenesis but also leukemogenesis independent of the c-Myc activation pathway. Finally, we will discuss our hypothesis that FIRΔexon2 interferes with FBW7, that FIRΔexon2 inhibits PP1 in the EGFR pathway, and that FIR haploinsufficiency is potentially associated with protein expression through transcriptional and post-transcriptional mechanisms.

High-throughput screening of extended RAS mutations based on high-resolution melting analysis for prediction of anti-EGFR treatment efficacy in colorectal carcinoma.

OBJECTIVES: Recent studies have demonstrated that, in advanced colorectal carcinoma (CRC) patients, extended RAS (in KRAS exons 2-4 and NRAS exons 2-4) and BRAF mutations are negative predictors for anti-EGFR treatment efficacy and negative prognostic factor, respectively. Thus, high-throughput and cost-effective methods for identification of the mutation status are required. DESIGN AND METHODS: We developed a PCR-high-resolution melting (HRM)-based method for screening extended RAS and BRAF mutations, and relative frequency of mutations in formalin-fixed paraffin-embedded samples of CRC was analyzed. RESULTS: Among 93 CRC samples, 29 harbored mutations in KRAS exon 2, and 9 harbored mutations in BRAF exon 15. Analysis of 55 KRAS exon 2 and BRAF exon 15 wild-type CRC samples identified the following mutations: 1/55 in exon 3 and 2/55 in exon 4 of KRAS; 1/55 in exon 2, 3/55 in exon 3, and 0/55 in exon 4 of NRAS. CONCLUSIONS: Our PCR-HRM method will enable rapid determination of the extended RAS and BRAF mutation status prior to anti-EGFR treatment in the clinical setting.

Moesin is a possible target molecule for cytomegalovirus-related Guillain-Barré syndrome.

OBJECTIVE: Previous histochemical studies in the demyelinating form of Guillain-Barré syndrome (GBS), acute inflammatory demyelinating polyneuropathy (AIDP), have shown complement deposition on the surface of Schwann cells, and therefore unknown epitopes would be present on the outer surface of Schwann cells. METHODS: We used a proteomic-based approach to search for the target molecules of AIDP in the extracted proteins from schwannoma cells. Sera were obtained from 40 patients with GBS, 31 controls with inflammatory disease, and 46 normal controls. RESULTS: We found that patients with AIDP after cytomegalovirus (CMV) infection have serum autoantibodies against membrane-organizing extension spike protein (moesin), which is expressed in the Schwann cell processes at the nodes of Ranvier and is crucial for myelination. Of the 40 patients with GBS, 6 had recent CMV infection and 5 of them (83%) had high levels of serum immunoglobulin G antibodies against moesin. The anti-moesin antibodies were found in none of the control subjects with disease including 5 with CMV infection but no neuropathy, and only 2 (4%) of the 46 normal control subjects. Immunocytochemistry showed that moesin was stained at the distal tips of schwannoma cells by sera from the patients with CMV-related AIDP but not by sera from controls. CONCLUSION: Moesin is a possible immunologic target molecule of pathogenic autoantibodies in patients with CMV-related AIDP. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that levels of serum anti-moesin antibodies accurately distinguishes CMV-related AIDP from non-CMV-related AIDP (sensitivity 83%, specificity 93%).