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In 2020, the worldwide incidence and mortality of colorectal cancer (CRC) were third and second, respectively. As the 5‐y survival rate is low when CRC is diagnosed at an advanced stage, a reliable method to predict CRC susceptibility is important for preventing the onset and development and improving the prognosis of CRC. Therefore, we focused on the normal colonic mucosa to investigate changes in gene expression that may induce subsequent genetic alterations that induce malignant transformation. Comprehensive gene expression profiling in the normal mucosa adjacent to colon cancer (CC) compared with tissue from non‐colon cancer patients was performed. PCR arrays and qRT‐PCR revealed that the expression of 5 genes involved in the immune response, including MYD88, was increased in the normal mucosa of CC patients. The expression levels of MYD88 were strikingly increased in precancerous normal mucosa specimens, which harbored no somatic mutations, as shown by immunohistochemistry. Microarray analysis identified 2 novel RNA‐controlling molecules, EXOSC3 and CNOT4, that were significantly upregulated in the normal mucosa of CC patients and were clearly visualized in the nuclei. Forced expression of EXOSC3 and CNOT4 in human colonic epithelial cells increased the expression of IFNGR1, MYD88, NFκBIA, and STAT3 and activated ERK1/2 and JNK in 293T cells. Taken together, these results suggested that, in the inflamed mucosa, EXOSC3‐ and CNOT4‐mediated RNA stabilization, including that of MYD88, may trigger the development of cancer and can serve as a potential predictive marker and innovative treatment to control cancer development., RNA‐controlling CNOT4 was significantly expressed in normal mucosae adjacent to colon cancers. IHC for CNOT4 was performed in 17 CCs and 15 NCCs, and representative images in paracancerous normal colonic mucosae, the paired tumor lesions in CCs, and normal mucosae in NCCs were displayed.

Information regarding the molecular features of pulmonary pleomorphic carcinoma (PPC) is insufficient. Here, we performed next-generation sequencing to determine the genomic and transcriptomic profiles of PPC. We sequenced the DNAs and RNAs of 78 specimens from 52 patients with PPC. We analyzed 15 PPC cases to identify intratumoral differences in gene alterations, tumor mutation burden (TMB), RNA expression, and PD-L1 expression between epithelial and sarcomatoid components. The genomic alterations of six cases of primary tumors and corresponding metastatic tumors were analyzed. KRAS mutations (27%) were the most common driver mutations, followed by EGFR (8%), and MET (8%) mutations. Epithelial and sarcomatoid components shared activating driver mutations, and there were no significant differences in CD274 expression or TMB between the two components. However, PD-L1 was highly expressed in the sarcomatoid component of several cases compared with the epithelial component. Primary and metastatic tumors shared oncogenic mutations among genes such as KRAS and TP53, and additional alterations including NOTCH4 mutations were specifically identified in the metastatic regions. Our data suggest that therapies targeting activating driver mutations may be effective for patients with PPC and that immune checkpoint inhibitors of PPC may be recommended after careful assessment of PD-L1 expression in each epithelial and sarcomatoid component.

Over the past 30 years, the therapeutic outcome for pancreatic ductal adenocarcinoma (PDAC) has remained stagnant due to the lack of effective treatments. We performed a genome-wide analysis to identify novel therapeutic targets for PDAC. Our analysis showed that Homo sapiens chromosome 16 open reading frame 74 (C16orf74) was upregulated in most patients with PDAC and associated with poor prognosis. Previously, we demonstrated that C16orf74 interacts with the catalytic subunit alpha of protein phosphatase 3 and plays an important role in PDAC invasion. However, the pathophysiologic function of C16orf74 is still unclear. In this study, through the analysis of C16orf74 interaction, we demonstrate a new strategy to inhibit the growth and invasion of PDAC. C16orf74 exists in the homodimer form under the cell membrane and binds integrin αVβ3 and is also involved in invasion by activating Rho family (Rac1) and MMP2. Considering that this dimeric form was found to be involved in the function of C16orf74, we designed an 11R-DB (dimer block) cell-permeable dominant-negative peptide that inhibits the dimer form of C16orf74. 11R-DB suppressed invasion and proliferation of PDAC cell lines by inhibiting phosphorylation of Akt and mTOR and also by inactivation of MMP2. 11R-DB also showed antitumor effects in an orthotopic xenograft model and peritoneal metastasis model. Thus, this study demonstrates that dimerized C16orf74, present in the cell membrane, is involved in pancreatic cancer invasion and proliferation. In addition, the C16orf74 dimer block cell-permeable peptide (11R-DB) has a potent therapeutic effect on PDAC in vitro and in vivo.

Locally advanced and metastatic invasive bladder cancer (BC) has a poor prognosis, and no advanced therapies beyond cisplatin‐based combination chemotherapy have been developed. Therefore, it is an urgent issue to elucidate the underlying mechanisms of tumor progression and metastasis of invasive BC for the development of new therapeutic strategies. Here, we clarified a novel role of exosomes containing ErbB2 and CRK in a formation of premetastatic niches and subsequent metastases. CRK adaptors were overexpressed in invasive UM‐UC‐3 BC cells. In an orthotopic xenograft model, metastases to lung, liver, and bone of UM‐UC‐3 cells were completely abolished by CRK elimination. Mass spectrometry analysis identified that ErbB2 was contained in UM‐UC‐3‐derived exosomes in a CRK‐dependent manner; the exosomes significantly increased proliferation and invasion properties of low‐grade 5637 BC cells and HUVECs through FAK and PI3K/AKT signaling pathways. In athymic mice educated with UM‐UC‐3‐derived exosomes, i.v. implanted UM‐UC‐3 cells were trapped with surrounding PKH67‐labeled exosomes in lung and led to development of lung metastasis with disordered vascular proliferation. In contrast, exosomes derived from CRK‐depleted BC cells failed to induce these malignant features. Taken together, we showed that CRK adaptors elevated the expression of ErbB2/3 in BC cells, and these tyrosine kinase/adaptor units were transferred from host BC cells to metastatic recipient cells by exosomes, leading to vascular leakiness and proliferation and contributing to the formation of distant metastasis. Thus, CRK intervention with ErbB2/3 blockade might be a potent therapeutic strategy for patients with ErbB2 overexpressing advanced and metastatic BC.

The combination of adenoviruses and chemotherapy agents is a novel approach for human cancer therapeutics. A meticulous analysis between adenovirus and chemotherapeutic agents can help to design an effective anticancer therapy. Human antigen R (HuR) is an RNA binding protein that binds to the AU-rich element (ARE) of specific mRNA and is involved in the export and stabilization of ARE-mRNA. Our recent report unveiled that the E4orf6 gene deleted oncolytic adenovirus (dl355) replicated for certain types of cancers where ARE-mRNA is stabilized. This study aimed to investigate whether a combined treatment of dl355 and Cis-diamminedichloroplatinum (CDDP) can have a synergistic cell-killing effect on cancer cells. We confirmed the effect of CDDP in nucleocytoplasmic HuR shuttling. In vitro and in vivo experiments showed the enhancement of cancer cell death by apoptosis induction and a significant reduction in tumor growth following combination treatment. These results suggested that combination therapy exerted a synergistic antitumor activity by upregulation of CDDP induced cytoplasmic HuR, which led to ARE mRNA stabilization and increased virus proliferation. Besides, the enhanced cell-killing effect was due to the activation of the intrinsic apoptotic pathway. Therefore, the combined treatment of CDDP and dl355 could represent a rational approach for cancer therapy.

Nilotinib is widely used for primary treatment of patients with chronic myelogenous leukemia (CML). We previously reported that use of an FRET-based drug sensitivity test at diagnosis efficiently predicts the response to treatment with imatinib or dasatinib. Here, we conducted a phase-II study to evaluate the efficacy and safety of nilotinib treatment and identify useful biomarkers, including results of the FRET-based drug sensitivity test, for predicting treatment response. Data from 42 patients were used in the analysis. Major molecular response (MMR), MR4, and MR4.5 rates at 12 months were 64.3, 42.9, and 28.6%, respectively. Grade 3/4 non-hematologic adverse events occurred in 11 patients (26.2%). The dose intensity of nilotinib ( 76.44%) and halving time (HT, 13.312 days) were identified as significant factors for MMR at 12 months. However, when we focused on patients whose dose intensity of nilotinib was 76.44%, the FRET-based drug sensitivity test became a predictive factor of MR4 achievement at 12 months. Our study reconfirmed the efficacy and safety of nilotinib treatment in CML patients. Moreover, our results suggest that the FRET-based drug sensitivity test is an independent predictor for achievement of MR4 in patients treated with a sufficient dose intensity of nilotinib.

Tumor budding is thought to represent a manifestation of epithelial-to-mesenchymal transition (EMT) and it has been correlated with poor patient outcomes in colorectal cancer (CRC). Our group recently demonstrated that human chorionic gonadotropin-β (hCGβ) modulates EMT in CRC. In the current study, based on the likely relationships between tumor budding and hCGβ expression, we examined their clinicopathologic significance in CRC. Twenty-eight of 80 (35.0%) CRC showed tumor budding. Tumor budding significantly correlated with lymph node metastasis (P < 0.01), pathologic stage (P < 0.01), lymphatic invasion (P = 0.044), and vascular invasion (P = 0.013). Thirteen of 80 (16.3%) CRC were hCGβ positive on immunohistochemistry. More tumor buds were present in the hCGβ-positive cases (P < 0.01), and tumor budding was significantly correlated with hCGβ positivity (P < 0.01). Cases with both tumor budding and hCGβ expression had the poorest prognosis compared with all other groups (P < 0.01). In conclusion, tumor budding and hCGβ expression are closely associated with EMT, and they are independent prognostic factors in CRC. They identify patients with an "EMT phenotype" who may respond to targeted molecular therapies.

Tyrosine kinase inhibitors (TKI) are used for primary therapy in patients with newly diagnosed CML. However, a reliable method for optimal selection of a TKI from the viewpoint of drug sensitivity of CML cells has not been established. We have developed a FRET-based drug sensitivity test in which a CrkL-derived fluorescent biosensor efficiently quantifies the kinase activity of BCR-ABL of living cells and sensitively evaluates the inhibitory activity of a TKI against BCR-ABL. Here, we validated the utility of the FRET-based drug sensitivity test carried out at diagnosis for predicting the molecular efficacy. Sixty-two patients with newly diagnosed chronic phase CML were enrolled in this study and treated with dasatinib. Bone marrow cells at diagnosis were subjected to FRET analysis. The ΔFRET value was calculated by subtraction of FRET efficiency in the presence of dasatinib from that in the absence of dasatinib. Treatment response was evaluated every 3 months by the BCR-ABL1 International Scale. Based on the ΔFRET value and molecular response, a threshold of the ΔFRET value in the top 10% of FRET efficiency was set to 0.31. Patients with ΔFRET value ≥0.31 had significantly superior molecular responses (MMR at 6 and 9 months and both MR4 and MR4.5 at 6, 9, and 12 months) compared with the responses in patients with ΔFRET value

The role of intraoperative pathological diagnosis for central nervous system (CNS) tumors is crucial for neurosurgery when determining the surgical procedure. Especially, treatment of carmustine (BCNU) wafers requires a conclusive diagnosis of high-grade glioma proven by intraoperative diagnosis. Recently, we demonstrated the usefulness of rapid immunohistochemistry (R-IHC) that facilitates antigen-antibody reaction under alternative current (AC) electric field in the intraoperative diagnosis of CNS tumors; however, a higher proportion of water and lipid in the brain parenchyma sometimes leads to freezing artifacts, resulting in poor quality of frozen sections. On the other hand, squash smear preparation of CNS tumors for cytology does not affect the frozen artifacts, and the importance of smear preparation is now being re-recognized as being better than that of the tissue sections. In this study, we established the rapid immunocytochemistry (R-ICC) protocol for squash smears of CNS tumors using AC electric field that takes only 22 min, and demonstrated its usefulness for semi-quantitative Ki-67/MIB-1 labeling index and CD 20 by R-ICC for intraoperative diagnosis. R-ICC by AC electric field may become a substantial tool for compensating R-IHC and will be applied for broad antibodies in the future.

We have previously reported that an adaptor protein CRK, including CRK-I and CRK-II, plays essential roles in the malignant potential of various aggressive human cancers, suggesting the validity of targeting CRK in molecular targeted therapy of a wide range of cancers. Nevertheless, the role of CRK in human bladder cancer with marked invasion, characterized by distant metastasis and poor prognosis, remains obscure. In the present study, immunohistochemistry indicated a striking enhancement of CRK-I/-II, but not CRK-like, in human bladder cancer tissues compared to normal urothelium. We established CRK-knockdown bladder cancer cells using 5637 and UM-UC-3, which showed a significant decline in cell migration, invasion, and proliferation. It is noteworthy that an elimination of CRK conferred suppressed phosphorylation of c-Met and the downstream scaffold protein Gab1 in a hepatocyte growth factor-dependent and -independent manner. In epithelial-mesenchymal transition-related molecules, E-cadherin was upregulated by CRK elimination, whereas N-cadherin, vimentin, and Zeb1 were downregulated. A similar effect was observed following treatment with c-Met inhibitor SU11274. Depletion of CRK significantly decreased cell proliferation of 5637 and UM-UC-3, consistent with reduced activity of ERK. An orthotopic xenograft model with bioluminescent imaging revealed that CRK knockdown significantly attenuated not only tumor volume but also the number of circulating tumor cells, resulted in a complete abrogation of metastasis. Taken together, this evidence uncovered essential roles of CRK in invasive bladder cancer through the hepatocyte growth factor/c-Met/CRK feedback loop for epithelial-mesenchymal transition induction. Thus, CRK might be a potent molecular target in bladder cancer, particularly for preventing metastasis, leading to the resolution of clinically longstanding critical issues.

MicroRNA (miRNA) can function as tumor suppressors or oncogenes, and also as potential specific cancer biomarkers; however, there are few published studies on miRNA in synovial sarcomas, and their function remains unclear. We transfected the OncomiR miRNA Precursor Virus Library into synovial sarcoma Fuji cells followed by a colony formation assay to identify miRNAs to confer an aggressive tumorigenicity, and identified miR-17-5p from the large colonies. MiR-17 was found to be induced by a chimeric oncoprotein SS18-SSX specific for synovial sarcoma, and all examined cases of human synovial sarcoma expressed miR-17, even at high levels in several cases. Overexpression of miR-17 in synovial sarcoma cells, Fuji and HS-SYII, increased colony forming ability in addition to cell growth, but not cell motility and invasion. Tumor volume formed in mice in vivo was significantly increased by miR-17 overexpression with a marked increase of MIB-1 index. According to PicTar and Miranda algorithms, which predicted CDKN1A (p21) as a putative target of miR-17, a luciferase assay was performed and revealed that miR-17 directly targets the 3′-UTR of p21 mRNA. Indeed, p21 protein level was remarkably decreased by miR-17 overexpression in a p53-independent manner. It is noteworthy that miR-17 succeeded in suppressing doxorubicin-evoked higher expression of p21 and conferred the drug resistance. Meanwhile, introduction of anti-miR-17 in Fuji and HS-SYII cells significantly decreased cell growth, consistent with rescued expression of p21. Taken together, miR-17 promotes the tumor growth of synovial sarcomas by post-transcriptional suppression of p21, which may be amenable to innovative therapeutic targeting in synovial sarcoma.

Sox10, one of the transcription factors, regulates Wnt/β-catenin signaling in diverse developmental processes in normal tissues. Sox10 is also expressed in variable solid tumors such as breast cancer, salivary tumor, hepatocellular carcinoma, ovarian tumor, nasopharyngeal carcinoma, prostate cancer, and digestive cancer. The role of Sox10 during tumorigenesis is still controversial, especially in digestive cancers; thus, we performed clinicopathological evaluation of Sox10 expression in 41 cases of diffuse-type gastric adenocarcinoma (DGA). We examined the expression of Sox10 by immunohistochemical staining and real-time quantitative reverse transcriptase PCR and evaluated the correlation between Sox10 expression and clinicopathological factors. A low-level expression of Sox10 was significantly associated with high-level venous invasion by immunohistochemical evaluation, while it was significantly associated with high-level lymphatic permeation when analyzed by real-time PCR assay. Survival analysis of 41 cases indicated that high level of vascular permeation was a statistically poor prognostic factor, suggesting that derogation of Sox10 would lead to unfavorable patients' outcome through the acceleration of vascular invasion. In this study, we revealed the clinical benefit of evaluation of Sox10 expression to predict the risk of vascular permeation which yields patients' poor prognosis in DGA.

In treating bladder cancer, determining the molecular mechanisms of tumor invasion, metastasis, and drug resistance are urgent to improving long-term patient survival. One of the metabolic enzymes, aldo-keto reductase 1C1 (AKR1C1), plays an essential role in cancer invasion/metastasis and chemoresistance. In orthotopic xenograft models of a human bladder cancer cell line, UM-UC-3, metastatic sublines were established from tumors in the liver, lung, and bone. These cells possessed elevated levels of EMT-associated markers, such as Snail, Slug, or CD44, and exhibited enhanced invasion. By microarray analysis, AKR1C1 was found to be up-regulated in metastatic lesions, which was verified in metastatic human bladder cancer specimens. Decreased invasion caused by AKR1C1 knockdown suggests a novel role of AKR1C1 in cancer invasion, which is probably due to the regulation of Rac1, Src, or Akt. An inflammatory cytokine, interleukin-1β, was found to increase AKR1C1 in bladder cancer cell lines. One particular non-steroidal anti-inflammatory drug, flufenamic acid, antagonized AKR1C1 and decreased the cisplatin-resistance and invasion potential of metastatic sublines. These data uncover the crucial role of AKR1C1 in regulating both metastasis and drug resistance; as a result, AKR1C1 should be a potent molecular target in invasive bladder cancer treatment.

The catalytic activities of covalent and ATP-dependent chromatin remodeling are central to regulating the conformational state of chromatin and the resultant transcriptional output. The enzymes that catalyze these activities are often contained within multiprotein complexes in nature. Two such multiprotein complexes, the polycomb repressive complex 2 (PRC2) methyltransferase and the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeler have been reported to act in opposition to each other during development and homeostasis. An imbalance in their activities induced by mutations/deletions in complex members (e.g. SMARCB1) has been suggested to be a pathogenic mechanism in certain human cancers. Here we show that preclinical models of synovial sarcoma—a cancer characterized by functional SMARCB1 loss via its displacement from the SWI/SNF complex through the pathognomonic SS18-SSX fusion protein—display sensitivity to pharmacologic inhibition of EZH2, the catalytic subunit of PRC2. Treatment with tazemetostat, a clinical-stage, selective and orally bioavailable small-molecule inhibitor of EZH2 enzymatic activity reverses a subset of synovial sarcoma gene expression and results in concentration-dependent cell growth inhibition and cell death specifically in SS18-SSX fusion-positive cells in vitro. Treatment of mice bearing either a cell line or two patient-derived xenograft models of synovial sarcoma leads to dose-dependent tumor growth inhibition with correlative inhibition of trimethylation levels of the EZH2-specific substrate, lysine 27 on histone H3. These data demonstrate a dependency of SS18-SSX-positive, SMARCB1-deficient synovial sarcomas on EZH2 enzymatic activity and suggests the potential utility of EZH2-targeted drugs in these genetically defined cancers.

Purpose: To develop a novel diagnostic method for the assessment of drug efficacy in chronic myeloid leukemia (CML) patients individually, we generated a biosensor that enables the evaluation of BCR-ABL kinase activity in living cells using the principle of fluorescence resonance energy transfer (FRET). Experimental Design: To develop FRET-based biosensors, we used CrkL, the most characteristic substrate of BCR-ABL, and designed a protein in which CrkL is sandwiched between Venus, a variant of YFP, and enhanced cyan fluorescent protein, so that CrkL intramolecular binding of the SH2 domain to phosphorylated tyrosine (Y207) increases FRET efficiency. After evaluation of the properties of this biosensor by comparison with established methods including Western blotting and flow cytometry, BCR-ABL activity and its response to drugs were examined in CML patient cells. Results: After optimization, we obtained a biosensor that possesses higher sensitivity than that of established techniques with respect to measuring BCR-ABL activity and its suppression by imatinib. Thanks to its high sensitivity, this biosensor accurately gauges BCR-ABL activity in relatively small cell numbers and can also detect Conclusion: In consideration of its quick and practical nature, this method is potentially a promising tool for the prediction of both current and future therapeutic responses in individual CML patients, which will be surely beneficial for both patients and clinicians. Clin Cancer Res; 16(15); 3964–75. ©2010 AACR.

BACKGROUND: Meningiomas are the most common primary brain tumors, accounting for about 27% of all intracranial tumors. Loss of Neurofibromin 2 (NF2) is found in about half of sporadic meningiomas, and recently, mutations in TRAF7, KLF4, AKT1, and SMO are reported in non-NF2 meningioma. To establish practical genotyping methods, we performed targeted amplicon sequencing with 45 meningioma specimens and evaluated the association with clinicopathological features. METHODS: Frozen samples of 45 meningiomas were fixed with PAXgene Tissue System (QIAGEN) and embedded in paraffin (PFPE). Amplicon sequencing panel targeted NF2, TRAF7, KLF4, AKT1 and SMO were designed by GeneRead Mix-n-Match panel and Custom panel (QIAGEN). Genomic DNA was extracted from PFPE tissues and libraries were prepared using GeneRead DNAseq Targeted Panels V2 (QIAGEN). The libraries were sequenced by the MiSeq (Illumina). The raw read data obtained from amplicon sequencing were processed by GeneRead Panel Variant Calling service for analysis of mutations and copy number alterations (CNA). RESULTS: Thirty three cases (73%) harbored NF2 loss, in which 20 cases (61%) simultaneously carried NF2 mutation. Mutations in TRAF7, KLF4, AKT1, and SMO were observed in 6 (13 %), 4 (9 %), 2 (4 %) and 0 (0%) cases, respectively. Altogether, 40 of 45 case (89 %) carried at least one or more gene alteration including mutations in 5 genes listed above and NF2 loss. Result of genotyping was correlated with histological subtypes as follows. All of nine fibrous meningiomas carried NF2 loss, while all of 4 meningiomas with secretory component carried both TRAF7 and KLF4 mutations. A case of chordoid meningioma harbored only AKT1-E17K mutation. CONCLUSIONS: Here we established the clinical sequence system for meningioma by targeted amplicon sequencing with desktop sequencer in which we demonstrated favorable results for CNAs as well as mutations.

Tumor recurrence is a leading cause of cancer death, due to accumulated genomic alterations driving therapeutic resistance. Glioblastoma multiforme (GBM) is the most aggressive brain tumor with a high relapse rate. Identification of oncogenic driver mutations and development of effective targeted therapies are desired. To enable prediction of actionable somatic mutations in patients with finally GBM, we utilized Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT), a hybridization capture-based NGS targeted 341 key cancer genes in FFPE tumors, which is the first test in Japan. Paired analysis of primary and matched recurrence tumors in five glioma cases treated with radiotherapy and chemotherapy (cases with transition from grade II to IV, III to IV, and IV to IV) were subjected, and reproducibility of the detectable mutations was assessed using matched primary culture cells. Many somatic mutations and copy number alterations were reliably detected in primary and recurrent tumors concomitantly or exclusively. Here, we would like to discuss the significance of MSK-IMPACT analysis to guide decision of optimal molecular targeted therapy.

The signaling adaptor protein Crk has been shown to play an important role in various human cancers. However, its regulatory machinery is not clear. Here, we demonstrated that Crk induced EMT in A549 human lung adenocarcinoma cells through differential regulation of Rac1/Snail and RhoA/Slug, leading to decreased expression of E-cadherin and increased N-cadherin, fibronectin, and MMP2 expression. Cancer cells with mesenchymal features produced TGF-β and also increased the levels of TGF-β receptor. TGF-β increased the endogenous levels of Crk and also augmented Crk-dependent expression of Snail and Slug, and conversely TGF-β receptor inhibitor suppressed the levels of Snail and Slug. Overexpression of Crk was observed at the invasive front of human lung cancer tissues and was significantly associated with poor prognosis. Thus, TGF-β and Crk collaborate to form a positive feedback loop to facilitate EMT, which may lead to the malignancy of human cancers possibly being affected by their microenvironment.

Proapoptotic Bax is a member of the Bcl-2 family proteins, which have a key role in regulating programmed cell death. The intracellular localization and redistribution of Bax are important in promoting apoptosis. Bax contains a BH3 domain heterodimerizing with Bcl-2 and a hydrophobic transmembrane segment to be inserted in specified organelle membranes. In this study, Bcl-2 showed cytoplasmic localization in all of ten human lung cancer cell lines tested. Interestingly, Bax was localized in the nucleus in 7 cell lines, although Bax lacks nuclear import signals. This may allow cancer cells to escape from apoptosis. Why Bax is able to exist in the nucleus is still unclear. We hypothesized that mutation in the BH3 domain and / or transmembrane segment of Bax possibly causes intracellular Bax distribution. We analyzed the sequence of the bax gene in these cell lines and found only a silent point mutation at codon 184 (TCG-->TCA) in the transmembrane segment in all cell lines. This finding indicates that changes in cellular localization of Bax in lung cancer cell lines do not depend on bax mutation and that Bax is possibly translocated into the nucleus without any mutation. This is the first report showing that Bax with the normal amino acid sequence can be localized in the nucleus in established lung cancer cell lines without any treatment of the cells.

CD163 is a 130-kDa transmembrane protein expressed in human monocytes and macrophages that was initially identified as RM3/1 by Zwadlo et al in 1987.1 Previously, expression of CD163 was thought to be restricted to monocytes, macrophages, and neoplasms associated with monocyte/macrophage lineage.2 In fact, CD163 is widely used as an immunohistochemical marker of monocytes and macrophages in routine pathological diagnosis. The molecular function of CD163 includes internalization of hemoglobin-haptoglobin complexes, an erythroblast adhesion receptor, a receptor for tumor necrosis factor-like weak inducer of apoptosis (TWEAK), and a receptor for distinct pathogens.3–8 In addition, CD163 is also attracting attention as a marker of tumor-associated macrophage (TAM), which is associated with a worse prognosis in many cancers.9–11 Moreover, recent analyses have revealed that the tumor cell itself in breast, rectal, and bladder cancer expressed CD163 and that CD163 expression in each of the tumor cells was associated with poor prognosis,12–14 suggesting the novel function of CD163 associated with tumor progression. Meningioma is one of the most common intracranial tumors in adults and accounts for 20%–32% of total intracranial tumors.15,16 According to the World Health Organization (WHO) classification (2007), meningiomas are histologically classified into grade I, II, and III.17 About 90% of meningiomas correspond to grade I, benign tumor; however, ∼10% are classified as grade II or III, exhibiting an unfavorable clinical course,16 although it has been recently reported that atypical meningioma occupied up to 20% of meningiomas with use of the latest WHO classification,17 in which meningioma with increased mitotic activity or ≥3 of the following histological features, including hypercellularity, macronucleoli, small cell formation, patternless architecture, and necrosis, is defined as atypical meningioma (grade II). Grade II and III meningiomas represent a risk of recurrence of 30%–40% and 50%–80%, respectively, after surgical resection,19 and the 5-year survival rates among patients with grade II and III meningiomas were 67.5% and 60%, respectively.18 In addition, even benign meningioma of grade I sometimes shows recurrence and/or malignant progression.19,20 The therapeutic modality to high-grade meningioma includes surgical resection, preoperative embolization, adjuvant radiotherapy, and multidrug chemotherapy. There have been also some trials and retrospective reports on targeted molecular therapies, including gefitinib, erlotinib, imatinib, and bevacizumab.21–25 However, the treatment efficacy, especially of chemotherapy, was limited, and there is currently no standardized treatment for recurrent high-grade meningiomas after surgery and radiation therapy. Thus, the proper diagnosis of high-grade meningioma based on reliable molecular markers is requested to the neuropathologists, and the management of high-grade meningioma and recurrent benign meningioma is a clinically significant theme for neurosurgeons. Before starting this study, we were aware that CD163 is expressed in a subset of high-grade meningioma during the process of differential diagnosis to histiocytic tumors. Here, we analyzed the correlation of CD163 expression in meningioma and pathological atypical features. Moreover, we also examined the molecular function of CD163 in vitro and in vivo with use of meningioma cell lines, including primary culture cells derived from surgically resected meningioma specimens, and elucidated the novel mechanism of CD163 to promote tumor growth by preventing apoptosis.

Small cell glioblastoma is a histological subtype of glioblastoma with characteristic features of highly proliferative, monotonous small glial cells with high nuclear cytoplasm ratio. Morphologically, malignant lymphoma or small cell metastatic carcinoma should be carefully discriminated. Some cases are difficult to differentiate from anaplastic oligodendroglioma. In this report, we present a case of small cell glioblastoma of an elderly man. The lack of IDH1/2 mutation was confirmed by immunohistochemistry and direct sequencing. Fluorescence in situ hybridization revealed the lower rates of chromosome 1p and 19q deletion. Microsatellite analysis disclosed partial 10q alteration near the PTEN locus. Not only morphological and immunohistochemical examinations, but also cytogenetical investigations for IDH1/2 mutation, 1p/19q loss, and PTEN alteration, are strongly supportive methods for the differential diagnosis of small cell glioblastoma and anaplastic oligodendroglioma.

Oral squamous cell carcinoma (OSCC) is the most common head and neck cancers, and rank as one of the top ten cancers worldwide. More worrying is that the incidence of oral cancer appears to be increasing in many parts of the world. OSCC is characterized by a high degree of local invasiveness and a high rate of metastasis to the cervical lymph nodes. Survival of patients with OSCC has not improved in the last 40 years, despite recent advances in surgical procedures and the availability of new chemotherapeutic agents. In addition, surgical resection results in significant functional and cosmetic defects; therefore, it is important to develop conservative therapeutics, whereupon identification of markers representing OSCC aggressiveness would be worthwhile to decide the most suitable treatment for each patient from therapeutic options.

Synovial sarcoma is an obstinate, high-grade malignancy because of its modest responses to radiotherapy and chemotherapy; the identification of effective therapeutics for this sarcoma is therefore necessary. Inhibition of Src family kinases (SFKs) suppresses the proliferation of synovial sarcoma cells in vitro, as we have previously reported. In this study, to validate the efficacy of Src inhibition in vivo, we employed SU6656, which was originally identified as a specific SFK inhibitor. SU6656 treatment significantly impaired the growth of established, existing tumours formed by synovial sarcoma cells in mice. Tumour cell invasion into the surrounding tissues was also abolished by SU6656. It is noteworthy that SU6656 but not PP2 induced a defect in cleavage furrow formation during cytokinesis, resulting in G2/M accumulation and subsequent apoptosis. Intriguingly, SU6656 abrogated the catalytic activities of Aurora kinases and led to the down-regulation of phosphorylated histone H3 coincidently with p53 accumulation, as did the Aurora kinase inhibitor VX-680. Structural comparison indicated an extensive similarity between the catalytic domains of SFKs and Aurora kinases. The structural analysis also revealed the potential binding mode of SU6656 to the ATP-binding cleft of Aurora B via four hydrogen bonds. SU6656 prevented angiogenesis within the tumours by attenuating vascular endothelial growth factor (VEGF) production by tumour cells and the subsequent chemotaxis of endothelial cells; these effects were the result of the inhibition of SFKs but not Aurora kinases. Based on these results, we hereby report a novel property of SU6656 as a dual inhibitor of SFKs and Aurora kinases, the suppression of both of which effectively abrogates tumour development and the progression of synovial sarcoma in vivo.

The adaptor protein Crk mediates intracellular signaling related to cell motility and proliferation and is implicated in human tumorigenesis. The role of Crk in the growth of human sarcoma has remained unclear, however. The present study shows that Crk-induced activation of Src and subsequent signaling by p38 mitogen-activated protein kinase (MAPK) contribute to the enhanced proliferation of human synovial sarcoma cells. Depletion of Crk by RNA interference markedly inhibited proliferation of the synovial sarcoma cell lines HS-SYII, SYO-1, and Fuji as well as prevented anchorage-independent growth. Conversely, reconstitution with CrkII by authentic small interfering RNA–resistant Crk gene restored proliferation in Crk-silenced SYO-1 cells. Crk-depleted synovial sarcoma cells manifested enhanced transcriptional activity and expression of the p16INK4A gene, resulting in their accumulation in G1 phase of the cell cycle. In response to hepatocyte growth factor stimulation, Crk prominently induced the tyrosine phosphorylation of Grb2-associated binder 1 through activation of Src and focal adhesion kinase, and the Src family kinase inhibitor PP2 almost completely inhibited the proliferation of SYO-1 cells. Crk also induced the phosphorylation of p38 MAPK, and SB203580, a p38 MAPK–specific inhibitor, increased expression of p16INK4A gene in SYO-1 cells. Furthermore, SB203580 or depletion of p38 MAPK by small interfering RNA suppressed both the phosphorylation of Akt triggered by hepatocyte growth factor and the proliferation of SYO-1 cells. These results suggest that Crk promotes proliferation of human synovial sarcoma cells through activation of Src and its downstream signaling by a novel p38 MAPK-Akt pathway, with these signaling molecules providing potent new targets for molecular therapeutics. (Mol Cancer Res 2009;7(9):1582–92)

Angiogenesis is involved in various physiologic and pathological conditions, including tumor growth, and is tightly regulated by the orchestration of proangiogenic and antiangiogenic factors. Inhibition of vascular endothelial growth factor (VEGF), the best-established antiangiogenic treatment in cancer, has shown some effectiveness; however, the identification of novel regulators, whose function is independent of VEGF, is required to achieve better outcomes. Here, we show that transcription factor 8 (TCF8) is up-regulated in endothelial cells during angiogenesis, acting as a negative regulator. Furthermore, TCF8 is specifically expressed in the endothelium of tumor vessels. Tcf8-heterozygous knockout mice are more permissive than wild-type mice to the formation of tumor blood vessels in s.c. implanted melanoma, which seems to contribute to the more aggressive growth and the lung metastases of the tumor in mutant mice. Suppression of TCF8 facilitates angiogenesis in both in vitro and ex vivo models, and displays comprehensive cellular phenotypes, including enhanced cell invasion, impaired cell adhesion, and increased cell monolayer permeability due to, at least partly, MMP1 overexpression, attenuation of focal adhesion formation, and insufficient VE-cadherin recruitment, respectively. Taken together, our findings define a novel, integral role for TCF8 in the regulation of pathologic angiogenesis, and propose TCF8 as a target for therapeutic intervention in cancer. [Cancer Res 2009;69(4):1678–84]

Specific chromosomal translocations encoding chimeric transcription factors are considered to play crucial oncogenic roles in a variety of human cancers but the fusion proteins themselves seldom represent suitable therapeutic targets. Oncogenic TFE3 fusion proteins define a subset of pediatric renal adenocarcinomas and one fusion (ASPL-TFE3) is also characteristic of alveolar soft part sarcoma (ASPS). By expression profiling, we identified the MET receptor tyrosine kinase gene as significantly overexpressed in ASPS relative to four other types of primitive sarcomas. We therefore examined MET as a direct transcriptional target of ASPL-TFE3. ASPL-TFE3 binds to the MET promoter and strongly activates it. Likewise, PSF-TFE3 and NONO-TFE3 also bind this promoter. Induction of MET by ASPL-TFE3 results in strong MET autophosphorylation and activation of downstream signaling in the presence of hepatocyte growth factor (HGF). In cancer cell lines containing endogenous TFE3 fusion proteins, inhibiting MET by RNA interference or by the inhibitor PHA665752 abolishes HGF-dependent MET activation, causing decreased cell growth and loss of HGF-dependent phenotypes. MET is thus a potential therapeutic target in these cancers. Aberrant transcriptional up-regulation of MET by oncogenic TFE3 fusion proteins represents another mechanism by which certain cancers become dependent on MET signaling. The identification of kinase signaling pathways transcriptionally up-regulated by oncogenic fusion proteins may reveal more accessible therapeutic targets in this class of human cancers. [Cancer Res 2007;67(3):919–29]

BACKGROUND: For GBM treatment, in addition to the advancement of surgical procedure, uncovering the therapy-resistant mechanism is a crucial issue. To date, we have revealed the significance of epiregulin-mediated stemness induction for TMZ-resistance (Kohsaka, S., et al. Neuro-Oncol, 16, 960-970, 2014), and implication of glial-mesenchymal transition (GMT) for radiation resistance (Mahabir, R., et al., 16, 671-685, 2014). Since TCGA analysis revealed the frequent mutation in receptor tyrosine kinases (TKs) in GBM, several clinical trials for TK inhibitor (TKI) have been designed but no significantly effective protocol is established mainly due to the acquisition of resistance to TKIs. PURPOSE: To investigate the molecular machinery underlying TKI resistance, therapy-resistant KMG4 GBM cells against each EGFR, MET, and PDGFR were established and long-term profiling analysis with biological features was performed until day 0 to 150. RESULTS: Against our expectation, in spite of the usage of differential chemicals against individual TK as EGFR, MET, and PDGFR, all three TKI resistant GBM cells equally exhibited GMT feature in early stage around Day 50, but in the later stage this GMT profile transited to stemness-like profile both in vitro and in vivo. By microarray analysis of expression profiling, several genes were observed to be commonly elevated in all three TKI-resistant cells, and among them, IGFBP2 (insulin-like growth factor receptor binding protein2) was confirmed to be increased in four other GBM cell lines and several patient derived culture cells. Significance of IGFBP2 was proved by knockdown analysis in which siRNA for IGFBP2 re-sensitized the treatment efficiency in all three TKI-resistant cells. CONCLUSION: In the process of TKI-resistance, GBM exhibits profile transition from GMT to stemness, and IGFBP2-mediated signal can be a universal target to prevent acquisition of TKI resistance.

INTRODUCTION AND OBJECTIVES: The objective of this study were to investigate the genetic changes responsible for bladder cancer metastasis, using orthotopic metastatic mouse model, and to find new therapeutic targets of invasive bladder cancer. METHODS: Human UM-UC-3 bladder cancer cells were generated to express firefly luciferase 2 and red fluorescent protein tdTomato (UM-UC-3-tdTomato-luc2). Subsequently, we developed an orthotopic xenograft nude mouse model of bladder cancer by inoculating UM-UC-3-tdTomato-luc2 cells through a urethral catheter into the mouse bladder. We then performed bioluminescent imaging (BLI) to noninvasively monitor the growth of bladder tumors in their orthotopic sites. Two mice underwent autopsy after confirmation of lung or liver metastases using BLI. The primary and metastatic tumors were excised and plated on tissue culture dishes to generate bladder, lung, liver, and bone sublines. To examine the role of metastasis-related genes in bladder cancer, we then performed comparative microarray analyses of gene expression, and analyzed gene expression changes in bladder vs. lung, bladder vs. liver and bladder vs. bone. RESULTS: Among the 8 genes commonly up-regulated in metastatic sublines compared to bladder cells by our microarray analysis, the expression of aldo-keto reductase 1C1 (AKR1C1) was especially up-regulated. Furthermore, AKR1C1 was significantly upregulated in the 3 metastatic sublines by qRT-PCR and immunoblot analysis. In clinical samples, we observed increased expression of AKR1C1 in human metastatic tissues compared with the corresponding primary bladder cancer tissues by qRT-PCR and immunohistochemistry analysis. Knockdown of AKR1C1 using small interfering RNA downregulated expression levels of Rac1, phosphorylated Src, and phosphorylated FAK, accompanied by reduced invasive ability. Overexpression of AKR1C isoforms, including AKR1C1, has been demonstrated to be associated with drug resistance in various cancers. UM-CU-3 metastatic cells were more resistant to cisplatin than were UM-UC-3 wild-type cells, and AKR1C1 inhibitor flufenamic acid reversed cisplatin resistance in these cells. CONCLUSIONS: We found that AKR1C1 was up-regulated both in metastatic bladder cancer cells using an orthotopic mouse model and in metastatic sites of human surgical specimens. Our results demonstrate the role of AKR1C1 in regulating bladder cancer metastasis and drug resistance; therefore, AKR1C1 is a potential target for effective treatment of invasive bladder cancer.

Activation of the c-Met receptor tyrosine kinase through its ligand, hepatocyte growth factor (HGF), promotes mitogenic, motogenic, and morphogenic cellular responses. Aberrant HGF/c-Met signaling has been strongly implicated in tumor cell invasion and metastasis. Both HGF and its receptor c-Met have been shown to be overexpressed in human synovial sarcoma, which often metastasizes to the lung; however, little is known about HGF-mediated biological effects in this sarcoma. Here, we provide evidence that Crk adaptor protein is required for the sustained phosphorylation of c-Met-docking protein Grb2-associated binder 1 (Gab1) in response to HGF, leading to the enhanced cell motility of human synovial sarcoma cell lines SYO-1, HS-SY-II, and Fuji. HGF stimulation induced the sustained phosphorylation on Y307 of Gab1 where Crk was recruited. Crk knockdown by RNA interference disturbed this HGF-induced tyrosine phosphorylation of Gab1. By mutational analysis, we identified that Src homology 2 domain of Crk is indispensable for the induction of the phosphorylation on multiple Tyr-X-X-Pro motifs containing Y307 in Gab1. HGF remarkably stimulated cell motility and scattering of synovial sarcoma cell lines, consistent with the prominent activation of Rac1, extreme filopodia formation, and membrane ruffling. Importantly, the elimination of Crk in these cells induced the disorganization of actin cytoskeleton and complete abolishment of HGF-mediated Rac1 activation and cell motility. Time-lapse microscopic analysis revealed the significant attenuation in scattering of Crk knockdown cells following HGF treatment. Furthermore, the depletion of Crk remarkably inhibited the tumor formation and its invasive growth in vivo. These results suggest that the sustained phosphorylation of Gab1 through Crk in response to HGF contributes to the prominent activation of Rac1 leading to enhanced cell motility, scattering, and cell invasion, which may support the crucial role of Crk in the aggressiveness of human synovial sarcoma. (Mol Cancer Res 2006;4(7):499–510)

Crk is a signaling adaptor protein which is mostly composed of SH2 and SH3 domains, and has been shown to play a pivotal role in cell proliferation, differentiation, and migration. Because Crk was originally isolated as an avian sarcoma virus CT10 encoding oncoprotein v-Crk, we examined a potential role for c-Crk in the carcinogenesis of human cancers. First, to analyze gene mutations of c-Crk, we isolated a human bacterial artificial chromosome clone containing Crk genome and exon/intron structures. However, polymerase chain reaction–single strand conformation polymorphism methods failed to show any genomic mutations in the Crk exon which could be related to carcinogenesis. Second, immunohistochemical analysis of c-Crk-II demonstrated that the levels of c-Crk-II were significantly elevated in most of the tumors, particularly in the colon and lung cancers. Furthermore, immunoblot analysis using human lung cancer cell lines revealed that the expression levels of c-Crk-II were correlated to growth rates of cells. The elevated expression levels of c-Crk-II might be related to the development of human cancers.

Epithelial-to-mesenchymal transition (EMT) is a leading phenomenon implicated in morphogenesis, invasiveness and metastasis of cancer cells. Likewise, Crk adaptor proteins described to promote an epithelial-mesenchymal-like transition and are required for HGF-mediated cell spreading and breakdown of epithelial adherens junctions in MDCK kidney epithelial cells. In this study we show that overexpression of CrkI and CrkII; members of Crk adaptor family of signalling proteins in A549 lung adenocarcinoma cells induce morphological changes resemble mesenchymal cells with high motility and invasiveness potential in both in vitro and in vivo. Furthermore, CrkI and CrkII both induce EMT but mostly through different pathways, while CrkI had a significant effect on TGFβ1-SMAD pathway which might be the inducer of EMT, more than CrkII, CrkII which had a higher Rac1 activity in the other hand showed a prominent effect on the expression of transcriptional factors regulating EMT like Snail and Slug, leading to almost total loss of the cell-cell adhesion glycoprotein E-cadherin expression, as well as remarkable increases in the production of extracellular matrix metalloproteinase (MMP) 2. These effects were opposed by inhibiting Rac1 activity. In conclusion, we could describe that CrkI and CrkII have a differential effect on the EMT process via activating Rac1, MMPs production, and the potential effect on TGF-β signalling, highlighting novel regulatory mechanisms of the adaptor protein Crk, and its involvement in cancer metastasis. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A156. Citation Format: Aiman Elmansuri, Mishie Tanino, Roshan Mahabir, Lei Wang, Masumi Tsuda, Taichi Kimura, Hiroshi Nishihara, Shinya Tanaka. CrkI and CrkII adaptor proteins promote invasiveness and metastasis via epithelial-mesenchymal transition (EMT) in A549 lung adenocarcinoma cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A156.

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor. Despite technological advances in surgery, combined with regimens of radiotherapy and new generation chemotherapy, the median survival is still 15 months. Several molecular therapeutics targeting protein tyrosine kinases have recently been attempted; however, the emerging drug resistance is a crucial issue. Here, we established cell lines acquired drug resistance to individual inhibitor for major tyrosine kinase as EGFR, c-Met, or PDGFR that highly expressed in GBM, and characterized the underlying mechanisms. While initial 50 days starting inhibitor treatment, the cells exhibited distinct morphological changes of epithelial-mesenchymal transition (EMT) concomitant with up-regulation of Snail, Slug, and Mmp-2. Of note, further continuous drug treatment produced stemness-like properties in the cells. PCR array and microarray analysis have identified marked enhancement of several stemness-related genes including Sox2 and CXCL12. These findings show that suppression of EMT and/or stemness features of GBM may be an effective strategy to avoid the acquisition of resistance for molecular target therapy in GBM. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B119. Citation Format: Masumi Tsuda, Lei Wang, Mishie Tanino, Taichi Kimura, Hiroshi Nishihara, Shinya Tanaka. Mechanisms of drug resistance to molecular target therapeutics against tyrosine kinases as EGFR, c-Met, and PDGFR in GBM. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B119.

Background: The mesenchymal subgroup of glioblastoma is more prevalent in recurrent tumors, which are known to present a worst prognosis. Ionizing irradiation is a known cause of epithelial to mesenchymal transition (EMT) in various cell types, but yet is still a vital part of glioblastoma treatment. Here we show that this mesenchymal change is due to an EMT effect in response to irradiation, and reflects the expression of the transcription factor Snail. Purpose: In this study we investigated the effect of irradiation on the EMT process and relate it to the mesenchymal phenotype that is demonstrated clinically. [Materials and Methods] Using the LINAC III accelerator, malignant glioma cell lines KMG4 and T98 along with primary patient cultures cells were irradiated at single dose 10Gy and multi fractionated 20Gy. Using qRT-PCR and Western blot analysis, mRNA and proteins were quantified in both the apoptotic and repopulating cells after irradiation. The re-populating cells after 21 days were monitored for phenotypic changes by invasion and wound healing assays, stemness marker SOX2 was quantified by immunofluorescence and tumor reformation ability was assessed by colony formation and xenograft assays, mortality and morbidity was quantified by orthotopic transplant. siRNA was used to knockdown, Snail, and transient overexpression of Snail gene, was done to determine the exact role that it plays in the progression to more mesenchymal phenotypes. We examined the phenotypic changes that occur based on standard EMT findings, including motility, invasiveness, expression of stemness markers, xenograft formation and colony formation assay. Results: In the short term, 48 hours after irradiation there is an increase in the EMT marker Snail and a further increase of this marker in the repopulating cells that would make up the recurrent tumor. Knockdown of Snail, not only results in decreased mesenchymal markers, but also decreased motility and invasion, these results are consistent in both single dose 10Gy and multi fractionated 20Gy irradiation levels. We also showed that the phosphorylation of the MAPK pathway plays a vital role in the downstream activation of EMT whereas the SMAD pathway remains non-activated and the inactivation of the GSK3β molecule results in higher Snail levels with a greater EMT effect. In cases where TGFβ concentration is increased, by co-culturing with fibroblasts, and/or monocytes, we showed that fibroblasts are the main source of TGFβ where as it is not secreted by glioma cells. Conclusion: Snail may be a useful target for inhibition to result in a decrease of recurrent mesenchymal phenotypes in malignant glioma producing a higher cure rate. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A57. Citation Format: Roshan Mahabir, Mishie Tanino, Aiman Elmansuri, Masumi Tsuda, Taichi Kimura, Lei Wang, Hiroshi Nishihara, Shinya Tanaka. The mesenchymal phenotype in recurrent glioblastoma is due to irradiation induced Snail expression and resultant EMT. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A57.

IL-6-dependent signaling pathway leading to Stat3 phosphorylation is reported to be involved in malignant phenotype of mesothelima. Altered expression of microRNA (miR) is observed in many cancers, however, the mechanism how miR regulates IL-6 expression in masothelioma is still unknown. We performed immunohistochemistry for phosphorylated Stat3 (pStat3) in 12 human mesotheliomas. Next, using 7 mesothelioma cell lines, mRNA expression of IL-6 and IL-6R, together with several miRs that regulated IL-6, and Stat 3 phosphorylation were examined by RT-PCR and immunoblotting. Five of 12 mesotheliomas showed strong expression of pStat3 in their nuclei and let 7a was identified as one of the candidate molecules that regulate IL-6 expression in mesothelioma by using 3’UTR reporter system. Moreover, IL-6 was found to regulate miR-153, miR-340, and miR-410 expressions. These findings suggest that let 7a, miR-153, -340, and 410 may be involved in malignant phenotype through regulation of IL-6 pathway in mesothelioma. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A231. Citation Format: Mishie A. Tanino, Shinji Kohsaka, Kazuhiro Yachi, Masumi Tsuda, Taichi Kimura, Hiroshi Nishihara, Shinya Tanaka. Let 7a regulates IL-6 expression in malignant mesothelioma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A231.