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Non-coding RNAs have an integral regulatory role in numerous functions related to lung cancer development. Here, we report identification of a novel lncRNA, termed T P53- i nhibiting l nc R NA ( TILR ), which was found to function as a constitutive negative regulator of p53 expression, including activation of downstream genes such as p21 and MDM2 , and induction of apoptosis. A proteomic search for TILR -associated proteins revealed an association with PCBP2, while the mid-portion of TILR was found to be required for both PCBP2 and p53 mRNA binding. In addition, depletion of PCBP2 resulted in phenocopied effects of TILR silencing. TILR was also shown to suppress p53 expression in a post-transcriptional manner, as well as via a positive feedback loop involving p53 and Fanconi anemia pathway genes. Taken together, the present findings clearly demonstrate that TILR constitutively inhibits p53 expression in cooperation with PCBP2, thus maintaining p53 transcriptional activity at a level sufficiently low for avoidance of spurious apoptosis induction.

The receptor tyrosine kinase-like orphan receptor 1 (ROR1) sustains prosurvival signalling directly downstream of the lineage-survival oncogene NKX2-1/TTF-1 in lung adenocarcinoma. Here we report an unanticipated function of this receptor tyrosine kinase (RTK) as a scaffold of cavin-1 and caveolin-1 (CAV1), two essential structural components of caveolae. This kinase-independent function of ROR1 facilitates the interactions of cavin-1 and CAV1 at the plasma membrane, thereby preventing the lysosomal degradation of CAV1. Caveolae structures and prosurvival signalling towards AKT through multiple RTKs are consequently sustained. These findings provide mechanistic insight into how ROR1 inhibition can overcome EGFR–tyrosine kinase inhibitor (TKI) resistance due to bypass signalling via diverse RTKs such as MET and IGF-IR, which is currently a major clinical obstacle. Considering its onco-embryonic expression, inhibition of the scaffold function of ROR1 in patients with lung adenocarcinoma is an attractive approach for improved treatment of this devastating cancer. Resistance to receptor tyrosine kinase inhibitors is a major obstacle in treatment of lung adenocarcinoma. Yamaguchi et al. identify the orphan receptor ROR1 as a potential target to overcome this resistance, by virtue of its role in promoting cell survival through stabilisation of caveolae.

We previously reported that ROR1 is a crucial downstream gene for the TTF‐1/NKX2‐1 lineage‐survival oncogene in lung adenocarcinoma, while others have found altered expression of ROR1 in multiple cancer types. Accumulated evidence therefore indicates ROR1 as an attractive molecular target, though it has yet to be determined whether targeting Ror1 can inhibit tumor development and growth in vivo. To this end, genetically engineered mice carrying homozygously floxed Ror1 alleles and an SP‐C promoter–driven human mutant EGFR transgene were generated. Ror1 ablation resulted in marked retardation of tumor development and progression in association with reduced malignant characteristics and significantly better survival. Interestingly, gene set enrichment analysis identified a hypoxia‐induced gene set (HALLMARK_HYPOXIA) as most significantly downregulated by Ror1 ablation in vivo, which led to findings showing that ROR1 knockdown diminished HIF‐1α expression under normoxia and clearly hampered HIF‐1α induction in response to hypoxia in human lung adenocarcinoma cell lines. The present results directly demonstrate the importance of Ror1 for in vivo development and progression of lung adenocarcinoma, and also identify Ror1 as a novel regulator of Hif‐1α. Thus, a future study aimed at the development of a novel therapeutic targeting ROR1 for treatment of solid tumors such as seen in lung cancer, which are frequently accompanied with a hypoxic tumor microenvironment, is warranted. Conditional Ror1 knockout mice carrying a human mutant EGFR transgene were established in the present study. Experiments with that animal model clearly demonstrated that Ror1 has crucial involvement in lung adenocarcinoma development and growth in vivo.

We previously identified receptor tyrosine kinase‐like orphan receptor 1 (ROR1) as a transcriptional target of the NKX2‐1/TTF‐1 lineage‐survival oncogene in lung adenocarcinoma. ROR1 consequently sustains a favorable balance between pro‐survival phosphatidylinositol 3‐kinase–protein kinase B and pro‐apoptotic apoptosis signal‐regulating kinase 1 (ASK1)‐p38MAPK signaling. In contrast to recent advances in understanding how ROR1 sustains pro‐survival signaling, the mechanism of ROR1 repression of pro‐apoptotic signaling remains rather elusive. In the present study, we investigated the underlying mechanism of ROR1‐mediated inhibition of the ASK1‐p38MAPK signaling pathway. Growth inhibition mediated by siROR1 was partially but significantly alleviated by ASK1 co‐knockdown in lung adenocarcinoma cell lines. Also, ASK1 phosphorylation at Thr845, which reflects its activated state, was clearly inhibited by ROR1 overexpression in both steady state and oxidative stress‐elicited conditions in MSTO‐211H cells. In addition, we found that ROR1 was physically associated with ASK1 at the C‐terminal serine threonine‐rich domain of ROR1. Furthermore, ROR1 kinase activity was shown to be required to repress the ASK1–p38 axis and oxidative stress‐induced cell death. The present findings thus support our notion that ROR1 sustains lung adenocarcinoma survival, at least in part, through direct physical interaction with ASK1 and consequential repression of the pro‐apoptotic ASK1–p38 axis in a ROR1 kinase activity‐dependent manner. We investigated the underlying mechanism of ROR1‐mediated inhibition of the ASK1‐p38MAPK signaling pathway. As a result, we have found that ROR1 inhibits ASK1 activity in an ROR1 kinase‐dependent manner via physical interaction at the C‐terminal serine threonine‐rich domain of ROR1.

Sphingolipids constitute a class of bio‐reactive molecules that transmit signals and exhibit a variety of physical properties in various cell types, though their functions in cancer pathogenesis have yet to be elucidated. Analyses of gene expression profiles of clinical specimens and a panel of cell lines revealed that the ceramide synthase gene CERS6 was overexpressed in non–small‐cell lung cancer (NSCLC) tissues, while elevated expression was shown to be associated with poor prognosis and lymph node metastasis. NSCLC profile and in vitro luciferase analysis results suggested that CERS6 overexpression is promoted, at least in part, by reduced miR‐101 expression. Under a reduced CERS6 expression condition, the ceramide profile became altered, which was determined to be associated with decreased cell migration and invasion activities in vitro. Furthermore, CERS6 knockdown suppressed RAC1‐positive lamellipodia/ruffling formation and attenuated lung metastasis efficiency in mice, while forced expression of CERS6 resulted in an opposite phenotype in examined cell lines. Based on these findings, we consider that ceramide synthesis by CERS6 has important roles in lung cancer migration and metastasis.

Emerging evidence suggests that microRNA, which are well‐conserved, abundant and small regulatory RNA, may be involved in the pathogenesis of human cancers. We recently reported that expression of let‐7 was frequently reduced in lung cancers, and that reduced let‐7 expression was significantly associated with shorter patient survival. Two members of the double‐stranded RNA‐specific endonuclease family, Dicer and Drosha, convert precursor forms of microRNA into their mature forms using a stepwise process. In the present study, we examined expression levels of these genes in 67 non‐small cell lung cancer cases, and found for the first time that Dicer expression levels were reduced in a fraction of lung cancers with a significant prognostic impact on the survival of surgically treated cases. It should be noted that multivariate COX regression analysis showed that the prognostic impact of Dicer (P = 0.001) appears to be independent of disease stage (P = 0.001), while logistic regression analysis demonstrated that the higher incidence of reduced Dicer expression in poorly differentiated tumors remained significant even after correction for other parameters (P = 0.02). Given the fundamental and multiple biological roles of Dicer in various cellular processes, our results suggest the involvement of reduced Dicer expression in the development of lung cancers, thus warranting further investigations of the underlying mechanisms, which can be expected to enhance understanding of the molecular pathogenesis of this fatal cancer. (Cancer Sci 2005; 96: 111–115)

Cell migration driven by actomyosin filament assembly is a critical step in tumour invasion and metastasis. Herein, we report identification of myosin binding protein H ( MYBPH ) as a transcriptional target of TTF‐1 (also known as NKX2‐1 and TITF1 ), a master regulator of lung development that also plays a role as a lineage‐survival oncogene in lung adenocarcinoma development. MYBPH inhibited assembly competence‐conferring phosphorylation of the myosin regulatory light chain (RLC) as well as activating phosphorylation of LIM domain kinase (LIMK), unexpectedly through its direct physical interaction with Rho kinase 1 (ROCK1) rather than with RLC. Consequently, MYBPH inhibited ROCK1 and negatively regulated actomyosin organization, which in turn reduced single cell motility and increased collective cell migration, resulting in decreased cancer invasion and metastasis. Finally, we also show that MYBPH is epigenetically inactivated by promoter DNA methylation in a fraction of TTF‐1 ‐positive lung adenocarcinomas, which appears to be in accordance with its deleterious functions in lung adenocarcinoma invasion and metastasis, as well as with the paradoxical association of TTF‐1 expression with favourable prognosis in lung adenocarcinoma patients. The TTF‐1 transcription factor is upregulated in lung adenocarcinomas, where it apparently suppresses malignant progression. One of its targets, MYBPH, inhibits Rho kinase 1 and hence cell motility and invasion, providing a potential explanation for the protective function of TTF‐1.

Elucidation of how pancreatic cancer cells give rise to distant metastasis is urgently needed in order to provide not only a better understanding of the underlying molecular mechanisms, but also to identify novel targets for greatly improved molecular diagnosis and therapeutic intervention. We employed combined proteomic technologies including mass spectrometry and isobaric tags for relative and absolute quantification peptide tagging to analyze protein profiles of surgically resected human pancreatic ductal adenocarcinoma tissues. We identified a protein, dihydropyrimidinase-like 3, as highly expressed in human pancreatic ductal adenocarcinoma tissues as well as pancreatic cancer cell lines. Characterization of the roles of dihydropyrimidinase-like 3 in relation to cancer cell adhesion and migration in vitro, and metastasis in vivo was performed using a series of functional analyses, including those employing multiple reaction monitoring proteomic analysis. Furthermore, dihydropyrimidinase-like 3 was found to interact with Ezrin, which has important roles in cell adhesion, motility, and invasion, while that interaction promoted stabilization of an adhesion complex consisting of Ezrin, c-Src, focal adhesion kinase, and Talin1. We also found that exogenous expression of dihydropyrimidinase-like 3 induced activating phosphorylation of Ezrin and c-Src, leading to up-regulation of the signaling pathway. Taken together, the present results indicate successful application of combined proteomic approaches to identify a novel key player, dihydropyrimidinase-like 3, in pancreatic ductal adenocarcinoma tumorigenesis, which may serve as an important biomarker and/or drug target to improve therapeutic strategies.

Accumulated evidence indicates that various types of miRNA are aberrantly expressed in lung cancer and secreted into the bloodstream. For this study, we constructed a serum diagnostic classifier based on detailed bioinformatics analysis of miRNA profiles from a training cohort of 143 lung adenocarcinoma patients and 49 healthy subjects, resulting in a 20 miRNA-based classifier. Validation performed with an independent cohort of samples from lung adenocarcinoma patients (n = 110), healthy subjects (n = 52) and benign pulmonary disease patients (n = 47) showed a sensitivity of 89.1% and specificity of 94.9%, with an area under the curve value of 0.958. Notably, 90.8% of Stage I lung adenocarcinoma cases were correctly diagnosed. Interestingly, this classifier also detected squamous and large cell lung carcinoma cases at relatively high rates (70.4% and 70.0%, respectively), which appears to be consistent with organ site-dependent miRNA expression in cancer tissues. In contrast, we observed significantly lower rates (0–35%) using samples from 96 cases of cancer in other major organs, with breast cancer the lowest. These findings warrant a future study to realize its clinical application as a part of diagnostic procedures for lung cancers, for which early detection and surgical removal is presently the only hope for eventual cure.

Background The Cockcroft–Gault formula is commonly used as a substitute for glomerular filtration rate (GFR) in Calvert's formula for carboplatin dosing, where adjusting serum creatinine measured using the enzymatic method with 0.2 mg/dL has been suggested in Japan. However, the effects of these adjustments on efficacy in patients with non‐small‐cell lung cancer remain unknown. Methods We conducted a post hoc analysis of the PREDICT1 study (CJLSG1201), a multicenter prospective observational trial of carboplatin–pemetrexed. Glomerular filtration rate values in Calvert's formula were back‐calculated from the administered dosages of carboplatin and the reported value of the target area under the curve. We estimated the serum creatinine adjustments and divided the patients into crude and adjusted groups. Results Patients in the crude group (N = 169) demonstrated similar efficacy to those in the adjusted group (N = 104) in progression‐free survival (PFS) and overall survival (OS) (hazard ratio [HR], 1.02; 95% confidence interval [CI], 0.76–1.35; p = 0.916 vs. HR, 0.87; 95% CI, 0.65–1.17; p = 0.363), with higher grade 3–4 hematologic toxicity. Among patients aged ≥75 years, the crude group (N = 47) showed superior efficacy compared with the adjusted group (N = 17) in PFS and OS (HR, 0.37; 95% CI, 0.20–0.69; p = 0.002 vs. HR, 0.43; 95% CI, 0.23–0.82; p = 0.010). Conclusions Serum creatinine adjustment may be associated with similar efficacy compared to the crude serum creatinine value. In older patients, the adjustment should be cautiously applied owing to the potential for reduced efficacy. Adjustment of serum creatinine measured using the enzymatic method with 0.2 mg/dL in creatinine clearance calculation using the Cockcroft–Gault formula is associated with similar clinical efficacy and a low incidence of toxicity compared with those of non‐adjusted values in patients with preserved renal function eligible for carboplatin–pemetrexed treatment. However, adjustments should be used with special caution in older patients owing to the potential for reduced efficacy.