Kimie Nomura

EML4-ALK fusion is linked to histological characteristics in a subset of lung cancers.

Introduction: Very recently, we have found a novel fusion product between the echinoderm microtubule-associated protein-like4 (EML4) and the anaplastic lymphoma kinase (ALK) in non-small cell lung cancers (NSCLCs). Tumors featuring EML4-ALK fusion constitute one subtype of NSCLC that might be highly sensitive to ALK inhibitors. Herein, we present results of a first large scale study of EML4-ALK fusion in lung cancers. Methods: Using reverse transcription-polymerase chain reaction for EML4-ALK fusion mRNA, we investigated 149 lung adenocarcinomas, 48 squamous cell carcinomas, 3 large-cell neuroendocrine carcinomas, and 21 small-cell carcinomas. For EML4-ALK-positive cancers, we further investigated the presence of ALK fusion proteins by immunohistochemistry. Results: Five of 149 adenocarcinomas (3.4%) showed EML4-ALK fusion mRNA, this being totally lacking in carcinomas of other types (0/72). In all the fusion-positive cases, ALK fusion protein could be detected in the cytoplasm immunohistochemically. The five fusion cases featured two EML4-ALK variant 1 fusions and three variant 2 fusions. Histologically, both variant 1 cases were mixed type adenocarcinomas, showing papillary with bronchioloalveolar components. Interestingly, all three variant 2 cases were acinar adenocarcinomas, the link being statistically significant (p = 0.00018). None of the five fusion-positive cases demonstrated any mutations of EGFR or KRAS, pointing to a mutually exclusive relationship (p = 0.014). There was no association with smoking habits. Conclusions: In the present first investigation of EML4-ALK fusion in a large study of lung cancers (5/221), we found an interesting histotype-genotype relationship. Furthermore, we could detect the fusion protein by immunohistochemistry, pointing to possible clinical applications.

ATP Citrate Lyase: Activation and Therapeutic Implications in Non–Small Cell Lung Cancer

Enhanced glucose and lipid metabolism is one of the most common properties of malignant cells. ATP citrate lyase (ACLY) is a key enzyme of de novo fatty acid synthesis responsible for generating cytosolic acetyl-CoA and oxaloacetate. To evaluate its role in lung cancer progression, we here analyzed ACLY expression in a subset of human lung adenocarcinoma cell lines and showed a relationship with the phosphatidyl-inositol-3 kinase-Akt pathway. The introduction of constitutively active Akt into cells enhanced the phosphorylation of ACLY, whereas dominant-negative Akt caused attenuation. In human lung adenocarcinoma samples, ACLY activity was found to be significantly higher than in normal lung tissue. Immunohistochemical analysis further showed phosphorylated ACLY overexpression in 162 tumors, well-correlating with stage, differentiation grade, and a poorer prognosis. Finally, to show the therapeutic potential and mechanism of ACLY inhibition for lung cancer treatment, we assessed the effect of RNA interference targeting ACLY on lipogenesis and cell proliferation in A549 cells. ACLY inhibition resulted in growth arrest in vitro and in vivo. Interestingly, increased intracellular lipids were found in ACLY knockdown cells, whereas de novo lipogenesis was inhibited. Supplementation of insulin could rescue the proliferative arrest elicited by ACLY inhibition; however, in contrast, fatty acid palmitate induced cell death. Taken together, these findings suggest that ACLY is involved in lung cancer pathogenesis associated with metabolic abnormality and might offer a novel therapeutic target.

Ki26894, a novel transforming growth factor‐β type I receptor kinase inhibitor, inhibits in vitro invasion and in vivo bone metastasis of a human breast cancer cell line

Transforming growth factor (TGF)‐β signaling has been shown to promote tumor growth and metastasis in advanced cancer. Use of inhibitors of TGF‐β signaling may thus be a novel strategy for treatment of patients with such cancers. In this study, we investigated the effects of a novel TGF‐β type I receptor (TβR‐I) kinase inhibitor, Ki26894, on bone metastasis of a highly bone‐metastatic variant of human breast cancer MDA‐MB‐231 cells, termed MDA‐MB‐231–5a‐D (MDA‐231‐D). Ki26894 blocked TGF‐β signaling in MDA‐231‐D cells, as detected by suppression of phosphorylation of Smad2 and inhibition of TGF‐β‐responsive reporter activity. Moreover, Ki26894 decreased the motility and the invasion of MDA‐231‐D cells induced by TGF‐βin vitro. Ki26894 also suppressed transcription of plasminogen activator inhibitor‐1 (PAI‐1), parathyroid hormone‐related protein (PTHrP), and interleukin‐11 (IL‐11) mRNA of MDA‐231‐D cells, which were stimulated by TGF‐β. X‐ray radiography revealed that systemic Ki26894 treatment initiated 1 day before the inoculation of MDA‐231‐D cells into the left ventricle of BALB/c nu/nu female mice resulted in decreased bone metastasis of breast cancer cells. Moreover, Ki26894 prolonged the survival of mice inoculated with MDA‐231‐D cells compared to vehicle‐treated mice. These findings suggest that TβR‐I kinase inhibitors such as Ki26894 may be useful for blocking the progression of advanced cancers. (Cancer Sci 2007; 98: 127–133)

Correlating Phosphatidylinositol 3-Kinase Inhibitor Efficacy with Signaling Pathway Status: In silico and Biological Evaluations

The phosphatidylinositol 3-kinase (PI3K) pathway is frequently activated in human cancers, and several agents targeting this pathway including PI3K/Akt/mammalian target of rapamycin inhibitors have recently entered clinical trials. One question is whether the efficacy of a PI3K pathway inhibitor can be predicted based on the activation status of pathway members. In this study, we examined the mutation, expression, and phosphorylation status of PI3K and Ras pathway members in a panel of 39 pharmacologically well-characterized human cancer cell lines (JFCR39). Additionally, we evaluated the in vitro efficacy of 25 PI3K pathway inhibitors in addition to conventional anticancer drugs, combining these data to construct an integrated database of pathway activation status and drug efficacies (JFCR39-DB). In silico analysis of JFCR39-DB enabled us to evaluate correlations between the status of pathway members and the efficacy of PI3K inhibitors. For example, phospho-Akt and KRAS/BRAF mutations prominently correlated with the efficacy and the inefficacy of PI3K inhibitors, respectively, whereas PIK3CA mutation and PTEN loss did not. These correlations were confirmed in human tumor xenografts in vivo, consistent with their ability to serve as predictive biomarkers. Our findings show that JFCR39-DB is a useful tool to identify predictive biomarkers and to study the molecular pharmacology of the PI3K pathway in cancer.

Correlation between morphology and EGFR mutations in lung adenocarcinomas Significance of the micropapillary pattern and the hobnail cell type.

The presence of epidermal growth factor receptor (EGFR) tyrosine kinase (TK) mutations significantly correlates with tumor sensitivity to TK inhibitors, particularly in lung adenocarcinomas, the predominant histological subtype in Japan and the United States. To clarify links between EGFR mutations and pathological findings in Japanese lung cancer, detailed pathological features of adenocarcinomas were examined using the WHO criteria as well as our cell type classification (hobnail, columnar and polygonal). Medical records were reviewed for a total of 107 surgically resected tumors. Clinicopathological factors were examined and correlations with EGFR status were evaluated. EGFR mutations were found in 63 patients (59%) distributed through all four exons examined (through exons 18-21). EGFR mutations were significantly associated with female gender (P=0.003), non-smoker status (P=0.008) and hobnail cell morphology (P<0.00001). In addition, detailed pathological examination showed significant associations with bronchioloalveolar carcinoma (BAC) component and a micropapillary pattern (MPP) (P=0.012 and 0.043, respectively). We conclude that characteristic histological features, i.e. the hobnail cell morphology and the presence of BAC component and MPP are good predictors of EGFR mutations in lung adenocarcinoma.

Lymphomatoid gastropathy: a distinct clinicopathologic entity of self-limited pseudomalignant NK-cell proliferation

Diagnostic errors in distinguishing between malignant and reactive processes can cause serious clinical consequences. We report 10 cases of unrecognized self-limited natural killer-cell proliferation in the stomach, designated as lymphomatoid gastropathy (LyGa). This study included 5 men and 5 women (age, 46-75 years) without any gastric symptoms. Gastroscopy showed elevated lesion(s) (diameter, ∼ 1 cm). Histologically, medium-sized to large atypical cells diffusely infiltrated the lamina propria and, occasionally, the glandular epithelium. The cells were CD2(+/-), sCD3(-), cCD3(+), CD4(-), CD5(-), CD7(+), CD8(-), CD16(-), CD20(-), CD45(+), CD56(+), CD117(-), CD158a(-), CD161(-), T cell-restricted intracellular antigen-1(+), granzyme B(+), perforin(+), Epstein-Barr early RNA(-), T-cell receptor αβ(-), and T-cell receptor γδ(-). Analysis of the 16 specimens biopsied from 10 patients led to a diagnosis of lymphoma or suspected lymphoma in 11 specimens, gastritis for 1 specimen, adenocarcinoma for 1 specimen, and LyGa or suspected LyGa for 3 specimens. Most lesions underwent self-regression. Three cases relapsed, but none of the patients died. According to conventional histopathologic criteria, LyGa is probably diagnosed as lymphoma, especially as extranodal natural killer/T-cell lymphoma, nasal type. However, LyGa is recognized as a pseudomalignant process because of its clinical characteristics. The concept of LyGa should be well recognized.

Activation of Glutathione Transferase P Gene by Lead Requires Glutathione Transferase P Enhancer I

Glutathione transferase P (GST-P) is specifically induced in rat liver and kidney by lead cation. The increase of GST-P mRNA after lead administration is blocked by actinomycin D, suggesting that GST-P production by lead is regulated at the transcriptional level. To further determine which part of the flanking region of the GST-P gene has the lead-responsive cis-element in vivo, we utilized transgenic rats with five different constructs having GST-P and/or chloramphenicol acetyltransferase coding sequence. We studied the effect of lead on these transgenic rats and on transfected NRK (normal rat kidney) cells and found that GST-P induction by lead is indeed regulated at the transcriptional level and that the GST-P enhancer I (GPEI) enhancer is an essential cis-element required for the activation of the GST-P gene by lead. GPEI consists of two AP-1 (c-Jun/c-Fos heterodimer) site-like sequences that are palindromically arranged and can bind AP-1. c-jun mRNA in the liver increased after lead administration and GST-P, and c-Jun had patchy expression in the same hepatocytes 24 h after lead exposure. These results suggest that activation of the GST-P gene by lead is mediated in major part by enhancer GPEI and that AP-1 may be involved at least partially. GPEI has been shown to have essential sequence information for the trans-activation of the GST-P gene during chemical hepatocarcinogenesis of the rat (Morimura, S., Suzuki, T., Hochi, S., Yuki, A., Nomura, K., Kitagawa, T., Nagatsu, I., Imagawa, M., and Muramatsu, M.(1993) Proc. Natl. Acad. Sci. U. S. A. 90, 2065-2068; Suzuki, T., Imagawa, M., Hirabayashi, M., Yuki, A., Hisatake, K., Nomura, K., Kitagawa, T., and Muramatsu, M. (1995) Cancer Res. 55, 2651-2655). The present study establishes that the same enhancer element does operate in the activation of the GST-P gene by lead regardless of the trans-activators involved.

Diverse Fusion Patterns and Heterogeneous Clinicopathologic Features of Renal Cell Carcinoma With t(6;11) Translocation

Renal cell carcinoma (RCC) with t(6;11) translocation, involving the transcription factor EB (TFEB) and Alpha, also known as MALATI, (TFEB RCC), is extremely rare, with only 20 cases reported to date. It may be frequently misdiagnosed because of a lack of established characteristics. TFEB RCCs are predominantly seen in younger patients and are generally indolent, with only 2 cases of metastasis. Genetic analysis has been limited, showing break points upstream of TFEB exon 3, yielding only a single transcript. We examined 3 new adult Japanese TFEB RCC cases by means of precise clinicopathologic, immunohistochemical, cytogenetic, and molecular analyses and compared them with 200 ordinary RCCs. A 57-year-old man was the oldest patient with TFEB RCC at the time of this study. Although the tumor had histology typical of translocation RCC, its fusion points were different between the genomic and transcript coordinates. A 37-year-old man had an aggressive course resulting in death. The tumor had 2 variants of messenger ribonucleic acid. A 47-year-old man showed borderline histologic and immunohistochemical features between TFEB RCC and chromophobe-type RCC. The tumor had a fusion point in TFEB exon 4, downstream of the wild-type ATG in exon 3. Nuclear expression of the TFEB protein was detected, and a Western blotting analysis identified a protein similar in size to the wild-type TFEB protein. Immunohistochemistry is useful for the diagnosis of these tumors, and TFEB RCCs have heterogeneous clinicopathologic features and more diverse fusion patterns than previously thought, requiring attention to polymerase chain reaction experiments for diagnosis. Our study will contribute to the correct diagnosis of TFEB RCC.

Immortal Epithelial Cells of Normal C3H Mouse Liver in Culture: Possible Precursor Populations for Spontaneous Hepatocellular Carcinoma

Long-term culture of primary hepatocytes derived from normal young male C3H/HeNJclMTV+ (C3H) and C57BL/6NJcl (C57) mice, respectively known for very high and low incidences of spontaneous hepatoma, resulted in development of multiple slowly growing epithelial colonies in the C3H case, the number of colonies being increased five-fold when 1.5 mM phenobarbital was added to the culture medium. On the other hand, the primary culture cells from C57 mouse liver gave rise to such epithelial colonies only very rarely, even with phenobarbital. Immunohistochemical investigation revealed alpha-fetoprotein and/or albumin production by the colony cells and ultrastructural analysis also revealed some hepatocytic features in them. Subculturing of individual colonies gave rise to cell lines which could be repeatedly passaged. Two of five lines implanted into athymic nude mice manifested tumorigenicity, the resultant neoplasms being diagnosed as a trabecular hepatocellular carcinoma and an adenocarcinoma. The experimental data suggest that the colony-forming immortal epithelial cells possibly represent early phase precursors of spontaneous mouse hepatocellular carcinomas. This culture system is expected to be useful for future elucidation of the mechanisms underlying spontaneous mouse hepatocarcinogenesis.

Genetic instability in lung cancer: concurrent analysis of chromosomal, mini- and microsatellite instability and loss of heterozygosity

To investigate what kind of genetic instability plays important roles in lung carcinogenesis, we analyzed micro- and minisatellite instability, loss of heterozygosity (LOH) and chromosome instability in 55 cases of lung cancer, including, 10 squamous cell, 5 large cell, and 3 small cell carcinomas, and 37 adenocarcinomas. Analysis of minisatellite instability, the mechanism of which is different from microsatellite instability, has not been reported previously. Minisatellite instability was detected in only one case (1/55, 1.8%), and the frequency of microsatellite instability was low, being found only in three cases (3/55, 5.5%). In contrast, LOH, for at least in one locus, was observed in 27 cases (49.1%). In adenocarcinomas, the frequency of LOH was higher in poorly differentiated compared to more differentiated carcinomas. For chromosome instability, a similar correlation between differentiation grade and instability was observed in adenocarcinomas. And instability was more common in large cell and small cell carcinomas than in adenocarcinomas. Our analysis showed that chromosome instability and LOH, rather than mini- and microsatellite instability, play significant roles in the development of lung cancer.