Futoshi Kurimoto

Altered expression of several genes in highly metastatic subpopulations of a human pulmonary adenocarcinoma cell line

Non-small cell lung cancer is associated with approximately 85% mortality due to its high metastatic potential. Therapeutic efforts have failed to produce a significant improvement in prognosis. In this situation, a better understanding of the key factors of metastasis may be useful for designing new molecular targets of therapy. In order to identify these factors, we compared the expression profiles of two subpopulations of an adenocarcinoma cell line with a high metastatic potential, PC9/f9 and PC9/f14, with the parent cell line, PC9, using a cDNA array. The expression of 15 genes was found to be significantly enhanced or reduced in the highly metastatic subpopulations. The expression of matrix metalloproteinase-2 (MMP-2), plasminogen activator inhibitor-1 (PAI-1) and interleukin-1 (IL-1 alpha) were upregulated in the highly metastatic subpopulations, while the expression of carcinoembryonic antigen (CEA), caspase-5, Fas ligand, Prk/FNK, cyclin E, cyclin B1, Ki-67, proliferating cell nuclear antigen (PCNA), Smad4, macrophage proinflammatory human chemokine-3 alpha (MIP-3 alpha)/LARC, Met and CD44 were downregulated. Data from the literature suggest that the altered expression of MMP-2, PAI-1, IL-1 alpha, CEA, caspase-5, Fas ligand, Prk/FNK and Smad4 promotes the highly metastatic phenotype. The differential expression of these genes was confirmed by Northern blot analysis, standard reverse transcription-polymerase chain reaction (RT-PCR) and real-time quantitative RT-PCR. This analysis in subpopulations of a lung cancer cell line indicated that the highly metastatic potential of lung cancer may be induced not by an alteration in the expression of a single gene, but by the accumulation of alterations in the expression of several genes involved in extracellular matrix (ECM) adhesion disruption, ECM degradation, escape from apoptosis, and resistance to transforming growth factor-beta(1) (TGF-beta(1)). Strategies for inhibiting metastasis of pulmonary adenocarcinoma should be designed accordingly.

Alteration of the PTEN/MMAC1 gene locus in primary lung cancer with distant metastasis

The PTEN/MMAC1 gene located at 10q23, has been proposed to be a tumor suppressor gene. To determine the involvement of alteration of the PTEN/MMAC1 gene in carcinogenesis and the progression of primary lung cancers, we analyzed tumor samples of primary and distant metastatic sites and normal lung tissue samples of 30 patients with advanced lung cancer with distant metastasis. The tissues were analyzed for allelic deletion and mutational inactivation of PTEN/MMAC1 by loss of heterozygosity (LOH) analysis, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), and direct sequence analysis. LOH of the PTEN/MMAC1 locus was common in each histologic type of primary lung cancer. In this study, the overall allelic deletion rate was 33.3% (7/21). Allelic loss at the primary site and that at the metastatic site of each patient, were identical; in most cases, it seemed that the allelic loss had occurred before metastasis. Sequence analysis of the PTEN/MMAC1 gene revealed a G to C substitution located 8 bp upstream of the coding region of exon 1 and which seems to be a polymorphism, in 4 of the 30 cases. Somatic mutations of the PTEN/MMAC1 gene were not identified in any of the tumors at the primary and metastatic sites. These data indicate that point mutations in the PTEN/MMAC1 gene are probably not an important factor in tumorigenesis and the progression of a major subset of lung cancers. Due to frequent allelic loss at the PTEN/MMAC1 locus occurring at a stage earlier than the metastatic process, alternative mechanisms in which the remaining allele is inactivated such as methylation or homozygous deletion of a small region of the gene that can not be detected by the usual analysis, or alteration of other important tumor suppressor genes lying close to the PTEN/MMAC1 gene on 10q23, may be involved in the tumorigenesis of lung cancers of all histologic subtypes.

The promoter region of the human BUBR1 gene and its expression analysis in lung cancer

Mitotic checkpoint impairment is present in human lung cancers with chromosomal instability (CIN). Spindle-checkpoint genes have been reported to be mutated in several human cancers, but these mutations are infrequent. Recent reports suggest that the hBUBR1 gene may play an important role in mitotic checkpoint control and in mitotic checkpoint impairment in human cancers. We analyzed the expression of hBUBR1 in lung cancer cell lines using real time quantitative RT-PCR. The expression of BUBR1 was found to be up-regulated in all of these cell lines. In addition, we cloned and characterized the promotor region of hBUBR1 and determined its genomic structure, which includes 23 exons. The open reading frame (ORF) of the hBUBR1 gene comprises exons 1 through 23. There are GC-rich regions located at the flanking region and about 150 bp upstream from exon 1. The promoter region (424 bp upstream from exon 1) showed promoter activity and includes multiple transcription factor consensus binding motifs, including those for Sp1, Nkx-2, CdxA, SRY, MyoD, Ik-2, HNF-3b, Staf, Oct-1, Nkx-2, v-Myb, and AML 1a. Multiple pathways leading to activation of those binding factors may contribute to hBUBR1 gene transcription. Knowledge of the genomic structure and the promoter region of the hBUBR1 gene will facilitate investigation of its role in mitotic checkpoint control and tumor progression in human cancers.

Reduced transcription of the RB2/p130 gene in human lung cancer

Reduced expression of the retinoblastoma gene (RB)2/p130 protein, as well as mutation of exons 19, 20, 21, and 22 of the same gene, has been reported in primary lung cancer. However, it has been suggested by other investigators that mutational inactivation and loss of the RB2/p130 gene and protein, respectively, are rare events in lung cancer. In order to determine the contribution and mechanisms of RB2/p130 gene inactivation to lung cancer development and progression, we quantified RB2/p130 mRNA expression levels in a range of human lung cancer cell lines (n = 13) by real‐time reverse transcription (RT)‐polymerase chain reaction (PCR) analysis. In comparison to normal lung tissue, reduced transcription of the RB2/p130 gene was found in all small cell lung cancer cell lines examined, along with six out of the eight nonsmall cell lung cancers tested, most of which had inactivation of RB/p16 pathway. On the basis of Western blot analysis, the expression of RB2/p130 protein was consistent with RNA expression levels in all lung cancer cell lines examined. In addition, the mutational status of the RB2/p130 gene (specifically, exons 19, 20, 21, and 22) was determined in 30 primary lung cancers (from patients with distant metastasis) and 30 lung cancer cell lines by PCR‐single strand conformation polymorphism (SSCP) analysis and direct DNA sequencing. There was no evidence of somatic mutations within the RB2/p130 gene in the 60 lung cancer samples (both cell lines and tumors) assessed, including the 11 lung cancer cell lines that displayed reduced expression of the gene. Furthermore, hypermethylation of the RB2/p130 promoter was not found in any of the above‐mentioned 11 cell lines, as determined by a DNA methylation assay, combined bisulfite restriction analysis (COBRA). The results of the present study suggest that the reduced RB2/p130 expression seen in lung cancer may be in part transcriptionally mediated, albeit not likely via a mechanism involving hypermethylation of the RB2/p130 promoter. The observed reduction in RB2/p130 gene expression may be due to histone deacetylation, altered mRNA stability, and/or other forms of transcriptional regulation.

Concurrent chemoradiotherapy followed by consolidation chemotherapy with bi-weekly docetaxel and carboplatin for stage III unresectable, non-small-cell lung cancer: clinical application of a protocol used in a previous phase II study.

PURPOSE To assess the clinical applicability of a protocol evaluated in a previously reported phase II study of concurrent chemoradiotherapy followed by consolidation chemotherapy with bi-weekly docetaxel and carboplatin in patients with stage III, unresectable, non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS Between January 2000 and March 2006, 116 previously untreated patients with histologically proven, stage III NSCLC were treated with concurrent chemoradiotherapy. Radiation therapy was administered in 2-Gy daily fractions to a total dose of 60 Gy in combination with docetaxel, 30 mg/m(2), and carboplatin at an area under the curve value of 3 every 2 weeks during and after radiation therapy. RESULTS The median survival time for the entire group was 25.5 months. The actuarial 2-year and 5-year overall survival rates were 53% and 31%, respectively. The 3-year cause-specific survival rate was 60% in patients with stage IIIA disease, whereas it was 35% in patients with stage IIIB disease (p = 0.007). The actuarial 2-year and 5-year local control rates were 62% and 55%, respectively. Acute hematologic toxicities of Grade ≥3 severity were observed in 20.7% of patients, while radiation pneumonitis and esophagitis of Grade ≥3 severity were observed in 2.6% and 1.7% of patients, respectively. CONCLUSIONS The feasibility of the protocol used in the previous phase II study was reconfirmed in this series, and excellent treatment results were achieved.

Mutation analysis of the gene encoding the human mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R) in human cell lines resistant to growth inhibition by transforming growth factor β1 (TGF-β1)

The mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R) is involved in activating the transforming growth factor beta(1) (TGF-beta(1)), an inhibitor of the cell proliferation, and limiting the insulin-like growth factor 2 mediated-growth stimulation. The M6P/IGF2R gene has been reported to be mutated and deleted in various cancers, and is a candidate tumor suppressor gene. We studied the genomic structure of the M6P/IGF2R gene and designed the intron primers to detect mutations in the M6P/IGF2R gene of genomic DNA samples. The M6P/IGF2R gene consists of 48 exons. The previously reported 23 mutations of the M6P/IGF2R gene in human cancers, liver, breast, and gastrointestinal tumors, are located in five exons, exon 27, 28, 31, 40, 48. Using the intron primers designed in this study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, and direct sequencing, we performed an initial analysis of the complete coding sequences of the M6P/IGF2R gene in 21 human cell lines resistant to growth inhibition by TGF-beta(1). An adenine-to-guanine transition, resulting in an asparagine-to-serine amino acid substitution, was found in one lung adenocarcinoma cell line at exon 40 where the mutation has been previously reported in human cancers. This is the first report of a mutation of the M6P/IGF2R gene in lung tumor. These results indicated that the mutation in M6P/IGF2R may be involved in human lung cancinogenesis.

The Long-Term Outcomes of Induction Chemoradiotherapy Followed by Surgery for Locally Advanced Non-Small Cell Lung Cancer

Background: Although the concept of induction therapy followed by surgical resection for locally advanced non-small cell lung cancer (LA-NSCLC) has found general acceptance, the appropriate indications and the strategy for this treatment are still controversial. Methods: From 2000 through 2008, 36 patients received concurrent chemoradiotherapy followed by surgery. We retrospectively reviewed these cases, analyzed the outcomes and examined the prognosis. Results: The median radiation dose given was 60 Gy. Chemotherapy included a platinum agent in all cases; cisplatin-based chemotherapy was administered to 9 cases, and a carboplatin-based chemotherapy regimen was administered to 27. A complete resection was performed in 94% of the patients. Seventeen (47.2%) patients exhibited a complete pathological response, and downstaging was induced in 26 (72%) cases. The morbidity and 30-day mortality rates were 11.1 and 0%, respectively. The 5-year overall survival rate in the patients with complete resection (n = 33) was 83.3%. Conclusions: Induction chemoradiotherapy followed by surgery for LA-NSCLC provided a favorable prognosis for selected patients. A complete pathological response was found in about half of cases. This strategy is feasible and was associated with low morbidity and high resectability rates, suggesting that it contributed to improving the treatment results.

Routine genetic testing of lung cancer specimens derived from surgery, bronchoscopy and fluid aspiration by next generation sequencing

After the development of EGFR tyrosine kinase inhibitors (TKIs), genetic testing of EGFR became required for effective treatment of lung cancer. Initially, the testing was conducted separately for each mutated region. However, many EGFR mutations have since been identified that determine the efficacy of EGFR-TKIs. Therefore, genetic testing of EGFR by next generation sequencing (NGS) may be a suitable strategy for lung cancer. Here we examined the applicability of the NGS method in regard to sensitivity, time and cost. A total of 939 specimens were obtained from 686 lung cancer patients at our hospital. DNA and RNA were simultaneously extracted from specimens derived from surgery, bronchoscopy, and fluid aspiration. Specimens included cerebrospinal fluid, pleural effusion, abdominal fluid, and pericardial effusion. From RNA, target regions (EGFR, KRAS, ALK fusion and RET fusion) were enriched by RT-PCR and sequenced with MiSeq. From DNA, PCR or PCR-RFLP conventional methods were performed. NGS and conventional methods were carried out routinely per week. Among the total 939 specimens, 38 specimens could not be examined with NGS. Among these, 34 specimens were analyzed by conventional testing with simultaneously extracted DNA. The remaining four specimens could not be tested with either method. Compared with the conventional method, the concordance rate of mutations was 99% (892/901), excluding specimens with NGS failure. The time period required from processing of specimens to results was 4 days, and the cost per sample was sufficiently low. In conclusion, the genetic testing with NGS method was useful for lung cancer treatment. The cost, sensitivity and time were able to tolerate routine examinations.

Phase II study of nimustine hydrochloride (ACNU) plus paclitaxel for refractory small cell lung cancer.

PURPOSE Bi-weekly administrations of nimustine hydrochloride (ACNU) plus paclitaxel were evaluated in this phase II study in patients with refractory small cell lung cancer (SCLC). METHODS Patients who had disease progression within 3 months after treatment with irinotecan (CPT-11)-containing regimens were entered. They were treated with every other week administrations of ACNU 50 mg/m(2) plus paclitaxel 110 mg/m(2) on day 1 over 2 weeks. RESULTS Twenty-four patients (20 males and 4 females, median age of 64 years, 17 patients with Eastern Cooperative Oncology Group [ECOG] performance status [PS] 0-1 and 7 patients with PS 2) participated in the trial. Of the 24 refractory patients after CPT-11 containing regimens, 17 patients had been given etoposide plus platinum. There were six partial responses, and an overall response rate of 25% (95% confidence interval, 10-46%) was obtained. The median time to progression and the median survival time after enrollment into this study were 2.8 and 5.8 months, respectively. The median overall survival from the first-line treatment was 19.5 months. The major toxicity was myelosuppression. Grade 4 neutropenia occurred in 13% of patients, and Grade 4 thrombocytopenia was observed in 13% of patients. There was one treatment-related death, attributed to pneumonitis. CONCLUSION Bi-weekly administrations of ACNU plus paclitaxel provided a practical and well-tolerated regimen that was active for CPT-11-refractory SCLC.

Simple method to detect important epidermal growth factor receptor gene mutations with bronchoscopic specimens of lung cancer patients for gefitinib treatment

Recent studies have demonstrated that epidermal growth factor receptor (EGFR) mutations are a predictive molecular marker of tumor response to gefitinib treatment in non-small-cell lung cancer (NSCLC). Early studies of EGFR mutations have been analyzed by direct sequencing with surgically resected specimens. However, it is often difficult to obtain sufficient and tumor-enriched tissue specimens from inoperative NSCLC patients for mutation analysis. Therefore, we set out to develop a simple, sensitive and reliable method based on polymerase chain reaction (PCR) and restriction endonuclease treatment to detect important EGFR mutations for gefitinib treatment, including G719S, deletion or insertion in exons 19 and 20, T790M, L858R and L861Q using bronchoscopic specimens. Two hundred and eleven bronchoscopic samples cytologically diagnosed as malignant were analyzed and mutations detected from 60 patients (28.4%). The present assay could detect deletion in exon 19 and L858R mutations in the presence of at least 1% and 5% mutant cells, respectively, from a background of normal cells. Comparison of mutation detection between bronchoscopic and surgical specimens from 42 patients indicated that the sensitivity of this assay using bronchoscopic specimens was 95% (18/19) with a specificity of 100% (23/23). Furthermore, deletion variants in exon 19 could be distinguished by native polyacrylamide gel electrophoresis. Consequently, this simple, sensitive and reliable assay can provide important information pertaining to optimal therapeutic strategies.