Kikuo Shigemitsu

Genetic alteration of the β-catenin gene (CTNNB1) in human lung cancer and malignant mesothelioma and identification of a new 3p21.3 homozygous deletion

The β-catenin gene (CTNNB1) has been shown to be genetically mutated in various human malignancies. To determine whether the β-catenin gene is responsible for oncogenesis in thoracic malignancies, we searched for the mutation in 166 lung cancers (90 primary tumors and 76 cell lines), one blastoma and 10 malignant mesotheliomas (two primary tumors and eight cell lines). Among the lung cancers, including 43 small cell lung cancers (SCLCs) and 123 non-small cell lung cancers (NSCLCs), we identified four alterations in exon 3, which is the target region of mutation for stabilizing β-catenin. One primary adenocarcinoma had a somatic mutation from C to G, leading to an amino acid substitution from Ser to Cys at codon 37. Among the cell lines, SCLC NCI-H1092 had a mutation from A to G, leading to an Asp to Gly substitution at codon 6, NSCLC HCC15 had a mutation from C to T, leading to a Ser to Phe substitution at codon 45, and NSCLC NCI-H358 had a mutation from A to G, leading to a Thr to Ala substitution at codon 75. One blastoma also had a somatic mutation from C to G, leading to a Ser to Cys substitution at codon 37. Among the 10 malignant mesotheliomas, we identified a homozygous deletion in the NCI-H28 cell line. Cloning of the rearranged fragment from NCI-H28 indicated that all the exons except exon 1 of the β-catenin gene are deleted and that the deletion junction is 13 kb downstream from exon 1. Furthermore, Northern blot analysis of 26 lung cancer and eight mesothelioma cell line RNAs detected ubiquitous expression of the β-catenin messages except NCI-H28, although Western blot analysis showed that relatively less amounts of protein products were expressed in some of lung cancer cell lines. Our findings suggest that the β-catenin gene is infrequently mutated in lung cancer and that the NCI-H28 homozygous deletion of the β-catenin gene might indicate the possibility of a new tumor suppressor gene residing in this region at 3p21.3, where various types of human cancers show frequent allelic loss.

Establishment of a large cell lung cancer cell line (Y-ML-1B) producing granulocyte colony-stimulating factor

We established a new lung cancer cell line, designated Y-ML-1B, from a lung cancer of a 70-year-old Japanese man with leukocytosis and thrombocytosis. Before surgical resection, the white blood cell and platelet counts were elevated to 34,400/mm3 and 668,000/mm3, respectively, and the granulocyte colony-stimulating factor (G-CSF) level in the serum was increased at 141 pg/mL. The primary tumor showed an undifferentiated morphology with large cells and induced extensive thickening of the pleura in the right hemithorax. The Y-ML-1B cells grow as a monolayer, with a doubling time of 19 hours, and are tumorigenic in nude mice, which showed a morphology similar to the primary tumor in xenografts. Analysis of the supernatant of cell culture medium of Y-ML-1B showed elevated levels of G-CSF and other cytokines such as interleukin (IL)-6, IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF), consistent with the high levels detected in the patients serum. Cytogenetic analysis revealed aneuploidy of greater than 56 in metaphases with many structural abnormalities. Mutation analysis of the tumor suppressor genes showed that Y-ML-1B is inactivated in TP53 and RASSF1A, but not in p14(ARF), p16(INK4A), or RB. Neither activating mutations of KRAS or NRAS nor amplification of MYC or MDM2 were detected. Y-ML-1B expressed N-cadherin but not E-cadherin. This newly established cell line might serve as a useful model for studying the molecular pathogenesis for large cell cancers of the lung which express high levels of cytokines.

A prospective, multi-institutional phase II study of induction chemoradiotherapy followed by surgery in patients with non-small cell lung cancer involving the chest wall (CJLSG0801)

OBJECTIVES The standard therapy for patients with T3N0-1M0 non-small cell lung cancer (NSCLC) involving the chest wall is considered surgical resection and adjuvant therapy. However, the compliance of adjuvant therapy is relatively low, and the prognosis for those patients has been unsatisfactory. Therefore, we conducted a phase II study of induction chemoradiotherapy followed by surgery with the aim of improving the survival. PATIENTS AND METHODS This treatment strategy consisted of induction chemotherapy (two cycles of cisplatin at 80mg/m2 on Day 1 and vinorelbine at 20mg/m2 on Days 1 and 8) concurrent with radiotherapy (40Gy in 20 fractions) followed by surgery. The inclusion criteria were patients with resectable T3N0-1M0 NSCLC involving the chest wall who were 20-70 years of age. The primary end point was the 3-year survival, assuming an expected rate of 67%. RESULTS From January 2009 to November 2012, 51 eligible patients were enrolled. Induction therapy was completed as planned in 49 (96%) patients without treatment-related death, and 25 (51%) had a partial response. Complete resection combined with the involved chest wall was achieved in 46 (92%) patients, and a pathologic complete response was seen in 13 (26%) patients. Five patients experienced major postoperative complications, and 1 patient died of acute exacerbation of interstitial pneumonia. With a median follow-up period of 42 months, the 3- and 5-year overall survivals of all registered patients were 77% and 63%, respectively. There was a significant difference in the survival rate between patients with a pathologic complete response and those with a residual tumor (p=0.039). CONCLUSION The mature results of this study in a multi-institutional setting showed the treatment strategy to be safe and effective with a high rate of pathologic response for patients with NSCLC involving the chest wall.