Shinichiro Miyoshi

Reduced expression of Dicer associated with poor prognosis in lung cancer patients

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)

A Method for Predicting Postoperative Lung Function and Its Relation to Postoperative Complications in Patients with Lung Cancer

We predicted the postoperative forced expiratory volume in 1 second (FEV1) with a formula based on the premise that the total number of subsegments was 42: postop FEV1 = [1 - (b - n)/(42 - n)] (preop FEV1), where n and b are the number of obstructed subsegments and total subsegments, respectively, in the resected lobe. It was assumed that b was 6, 4, and 12 in the right upper, middle, and lower lobes, respectively, and 10 each in the left upper and the left lower lobes. The obstructed subsegments, n, were obtained from the findings on bronchography or bronchofiberscopy or both before operation. The linear regression line derived from the correlation between predicted (x) and measured (y) FEV1 was y = 0.850x + 0.286 +/- 0.296 (standard error) (N = 52; r = 0.821; p less than 0.001). We calculated the predicted postoperative FEV1 in 188 patients with primary lung cancer. The predicted values were corrected with the regression equation just mentioned and then normalized by the patients height and sex (%FEV1(p,c). The correlation between %FEV1(p,c) and the surgical risk was studied. Postoperative respiratory complications were inversely related to %FEV1(p,c), and a significantly high incidence of complications (p less than 0.05) was observed in those whose %FEV1(p,c) was less than 60% of predicted normal. In aged patients (65 years old or more) without complications, %FEV1(p,c) was 67.3 +/- 18.0%; it was 52.2 +/- 12.8% in those with respiratory trouble and 53.3% +/- 9.6% in those with circulatory complications. The difference between groups with and without complications was significant (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of Postoperative Respiratory Failure in Patients Undergoing Lung Resection for Lung Cancer

To evaluate the correlation between predicted postoperative lung function and postoperative respiratory morbidity, 156 patients with lung cancer who underwent resection were classified into four groups based on the degree of postoperative problems: Group 1--no problems (116 patients); Group 2--retention of sputum or atelectasis requiring bronchofiberscopy two or more times (17 patients); Group 3--tracheostomy or mechanical ventilation for more than 2 days or both (14 patients); and Group 4--postoperative death (9 patients). The mean ages of Groups 2, 3, and 4 were significantly (p less than 0.05) higher than the mean age of Group 1. The predicted postoperative lung function (F) was assessed by the formula F = [1-(b-n)/(42-n)] x f, where f is the preoperative vital capacity or forced expiratory volume in one second, b is the number of subsegments of the resected lung lobe, and n is the number of subsegments obstructed by the tumor, which was assessed by the findings on the chest tomogram, on the bronchogram, at bronchofiberscopy, or a combination of these. The total number of subsegments was assumed to be 42. The predicted postoperative % FEV1 was 65.1 +/- 19.3% in Group 1,55.3 +/- 10.6% in Group 2,37.6 +/- 12.1% in Group 3, and 42.3 +/- 18.4% in Group 4. It was significantly (p less than 0.05) different between all the groups except between Groups 3 and 4. All 10 patients with a predicted postoperative % FEV1 of less than 30% were in Groups 3 and 4. We conclude that special attention to postoperative management is needed for patients whose predicted postoperative %FEV1 is lower than 30%.

Surgical results for small cell lung cancer based on the new TNM staging system

BACKGROUND Operation with combined chemotherapy has been recently recommended for very early stage of small cell lung cancer without lymph node metastasis. METHODS A retrospective study was undertaken in 91 patients who had undergone pulmonary resection for small cell lung cancer according to the new international staging system. RESULTS The 5-year overall probability of survival was 37.1%. The 5-year survival rate was 100% for p-stage 0, 56.1% for p-stage IA, 30.0% for p-stage IB, 57.1% for p-stage IIA, and 42.9% for p-stage IIB. In the p-stage IA-IIB patients who underwent a complete resection, the 5-year survival rate of the patients treated by operation with chemotherapy was better than that of patients treated by operation alone. In addition, the 5-year survival rate of the patients who had four or more courses of chemotherapy was 80.0%. CONCLUSIONS These results suggest that operation should be considered for p-stage IA-IIB patients and more than four courses of combined chemotherapy might be desirable in these resectable cases.

New prognostic indicator for non‐small‐cell lung cancer, quantitation of thymidylate synthase by real‐time reverse transcription polymerase chain reaction

Thymidylate synthase (TS) is an enzyme that catalyzes an important DNA biosynthesis process. The gene expression of TS has not been reported in non‐small‐cell lung cancer (NSCLC) patients. To clarify the correlation between TS mRNA levels and clinicopathological features of NSCLC, we examined 70 Stage I and II NSCLC patients for intra‐tumoral expression of TS using TaqMan reverse transcription polymerase chain reaction (RT‐PCR) assay and immunohistochemistry methods. We also investigated the TS promoter 28 bp polymorphism in 48 cancer tissues using PCR amplification of genomic DNA. Lung cancer tissue showed higher TS mRNA levels than normal lung tissue (Mann‐Whitney U‐tests; p = 0.0020). Further, TS mRNA expression was correlated with immunohistochemical TS expression (p = 0.029). We obtained 2 different DNA fragments, which indicated triple‐repeat (3R) and double‐repeat (2R) type alleles. Cancer tissues with the 3R/3R genotype showed significantly higher TS mRNA levels as compared to those with other genotypes (p = 0.0019). The TS genotype was also correlated with immunohistochemical TS expression (χ2 test; p = 0.0079). The disease‐free survival of the low TS mRNA level group was significantly better than those with high TS mRNA levels (log‐rank test; p = 0.010), however, there were no significant differences found by immunohistochemical evaluation (p = 0.34) or TS genotype analysis (p = 0.11). A multivariate analysis revealed that high TS mRNA levels independently contributed to disease‐free survival. The quantitation of TS mRNA levels is clinically more sensitive and useful for determining the prognosis of Stage I and II NSCLC patients than an immunohistochemical evaluation.

Clinical spectrum of congenital cystic disease of the lung in children

OBJECTIVES Congenital cystic lesions of the lung are uncommon but share similar embryologic and clinical characteristics. The purpose of this study is to review our institutional experience of congenital cystic lung disease, emphasizing the clinical spectrum of the disease related to age, and present some cases with unusual clinical manifestations. PATIENTS Between 1962 and 1996, 26 patients (9 females and 17 males) under 15 years old underwent evaluation and surgical treatment for congenital cystic lung disease. Seven patients were under 1 year old, and 19 were in over 1 year old. There were 13 bronchogenic pulmonary cysts, 6 pulmonary sequestrations, 4 congenital cystic adenomatoid malformations (CCAM), and 3 congenital lobar emphysemas. RESULTS All patients under 1 year old showed respiratory distress with mediastinal shift but no episodes of infection. In contrast, 13 of the 19 patients over 1 year old had symptoms of recurrent infection without respiratory distress. Five patients over 1 year old were entirely asymtomatic from birth. There were significant differences (P < 0.05) in the frequencies of respiratory distress and infection between the two groups (chi2-test). Lobectomy was performed in 21 patients, excision in 3 patients, segmentectomy in one patient, and exploration in one patient. There was no incident of postoperative mortality or morbidity except for one patient with CCAM complicated by reexpansion lung edema. Twenty-one patients at long-term follow-up from 2 to 30 years after surgery are doing well with no subsequent limitation of physical activities due to lung resection. CONCLUSIONS In patients under 1 year old, cystic lesions were discovered by respiratory distress; and in patients over 1 year old signs of infection were the most important clinical features. Early recognition of these relatively rare congenital cystic lung lesions would lead to the immediate, proper surgical intervention.

Intrathoracic neurogenic tumors—50 years' experience in a Japanese institution

OBJECTIVE Intrathoracic neurogenic tumors are relatively uncommon, and there have been few reports regarding their entire clinical characteristics in the Asian population. OBJECTIVES We retrospectively reviewed our Japanese institutional experience of intrathoracic neurogenic tumors, with emphasis on the clinical spectrum. METHODS We analyzed the records of 146 patients with intrathoracic neurogenic tumors who were treated over the past 50 years. There were 60 pediatric and 86 adult patients (74 males and 72 females). RESULTS There were 51 ganglioneuromas, 37 schwannomas, 30 neurofibromas, 18 neuroblstomas, 5 gangliobastomas, and 5 others, of which 136 cases were located in the posterior mediastinum, 9 in the chest wall, and 1 in the lung parenchyma. Neurogenic tumors were most commonly seen as a pediatric mediastinal tumor (46.2%), as compared to 11.2% in the adult population (P<0.001). Eighty-four percent of adult patients and 60% of pediatric patients were asymptomatic. In thirteen patients (8.9%), the tumor showed an intraspinal extension, the so-called dumbbell-type. Overall, 20.5% of the neoplasms were malignant, occurring predominantly in the first 5 years of life. Complete resection was performed in 95.7% cases for benign tumors and 63.3% for malignant tumors, including a laminectomy for six cases of the dumbbell-type. There were no operative deaths and minimal morbidity. CONCLUSIONS Age seemed to be the most important clinical parameter for distinguishing between histological type and rate of malignancy for neurogenic tumors. Recognition of this clinical spectrum will lead to the immediate and appropriate surgical intervention.

Surgical rescue for life-threatening hypoxemia caused by a mediastinal tumor

We recently encountered a patient with a large anterior mediastinal tumor who developed severe hypoxemia during general anesthesia. This life-threatening hypoxemia was treated by extracorporeal membrane oxygenation using emergent percutaneous cardiopulmonary support followed by extirpation of the tumor. We found that total arteriovenous shunt resulting from compression by the mediastinal tumor caused this severe hypoxemia (total obstruction of left main bronchus and of the right pulmonary artery).

p16INK4, pRB, p53 and cyclin D1 expression and hypermethylation of CDKN2 gene in thymoma and thymic carcinoma

There have been few reports on genetic alterations in thymomas. To investigate the expression of p16INK4A, RB, p53 and cyclin D1 in thymomas, we first examined 36 thymomas (non‐invasive type, 16 cases; invasive type, 20 cases) and 3 thymic carcinomas, using immunohistochemistry. Abnormal expression of p16INK4A, RB, p53 and cyclin D1 was observed in 18, 8, 10 and 7 cases, respectively. Only a subgroup of invasive thymomas and thymic carcinomas showed an inverse correlation between p16INK4A and RB expression. Subsequently, we examined the 36 thymomas and 4 thymic carcinomas for mutations in p53 and CDKN2 genes, using PCR‐SSCP and direct‐sequencing analyses. No mutation of these genes was detected in the thymomas and thymic carcinomas examined. A polymorphism in the 3′ untranslated region of exon 3 of CDKN2 was detected in 5 cases of thymoma. We searched for hypermethylation in the promoter region of CDKN2, observing it in 4 thymomas and 1 thymic carcinoma. Our data suggest that, unlike other more common cancers, alteration of the p53 gene may not play a significant role in the tumorigenesis of thymoma. However, inactivation of p16INK4A and RB may play a role in the progression of thymoma and thymic carcinoma. Int. J. Cancer 73:639–644, 1997.

Disruption of the RB pathway and cell-proliferative activity in non-small-cell lung cancers.

The pathway consisting of retinoblastoma protein (pRB), cyclin D1 and p16 (RB pathway) which is involved in the phosphorylation of pRB plays an important role in G1/S progression. The disruption of this RB pathway has been reported in several types of human neoplasm. An immunohistochemical study of 101 non‐small‐cell lung cancers (NSCLCs) showed loss of p16 is in 47 tumors (46.5%) and loss of pRB in 42 tumors (41.6%). In 79 of 101 NSCLCs (78.2%), the expression of p16 and pRB was complementary (p < 0.0001). Methylation of the cdkn2 gene was detected in 50% of p16‐negative tumors and in 11% of p16‐positive tumors. Aberrant expression of cyclin D1 was found in 45 tumors (44.5%). The cyclin‐D1‐positive tumors had significantly higher Ki‐67 indices than the cyclin‐D1‐negative tumors irrespective of the tumor p16 or pRB expression. Thus, 91 (90%) of 101 NSCLCs showed disturbed expression of at least 1 of the 3 components of the RB pathway. Our results suggest that the disruption of the RB pathway plays an important role in tumorigenesis in NSCLCs and that increased cyclin‐D1 expression leads to strong proliferative activity which may over‐ride the suppressive effect of p16 and pRB. Int. J. Cancer (Pred. Oncol.) 79:111–115, 1998.© 1998 Wiley‐Liss, Inc.