Hitoshi Tsuda

KIF5B-RET fusions in lung adenocarcinoma

We identified in-frame fusion transcripts of KIF5B (the kinesin family 5B gene) and the RET oncogene, which are present in 1–2% of lung adenocarcinomas (LADCs) from people from Japan and the United States, using whole-transcriptome sequencing. The KIF5B-RET fusion leads to aberrant activation of RET kinase and is considered to be a new driver mutation of LADC because it segregates from mutations or fusions in EGFR, KRAS, HER2 and ALK, and a RET tyrosine kinase inhibitor, vandetanib, suppresses the fusion-induced anchorage-independent growth activity of NIH3T3 cells.

One-step Nucleic Acid Amplification for Intraoperative Detection of Lymph Node Metastasis in Breast Cancer Patients

Purpose: Detection of sentinel lymph node (SLN) metastasis in breast cancer patients has conventionally been determined by intraoperative histopathologic examination of frozen sections followed by definitive postoperative examination of permanent sections. The purpose of this study is to develop a more efficient method for intraoperative detection of lymph node metastasis. Experimental Design: Cutoff values to distinguish macrometastasis, micrometastasis, and nonmetastasis were determined by measuring cytokeratin 19 (CK19) mRNA in histopathologically positive and negative lymph nodes using one-step nucleic acid amplification (OSNA). In an intraoperative clinical study involving six facilities, 325 lymph nodes (101 patients), including 81 SLNs, were divided into four blocks. Alternate blocks were used for the OSNA assay with CK19 mRNA, and the remaining blocks were used for H&E and CK19 immunohistochemistry–based three-level histopathologic examination. The results from the two methods were then compared. Results: We established CK19 mRNA cutoff values of 2.5 × 102 and 5 × 103 copies/μL. In the clinical study, an overall concordance rate between the OSNA assay and the three-level histopathology was 98.2%. Similar results were obtained with 81 SLNs. The OSNA assay discriminated macrometastasis from micrometastasis. No false positive was observed in the OSNA assay of 144 histopathologically negative lymph nodes from pN0 patients, indicating an extremely low false positive for the OSNA assay. Conclusion: The OSNA assay of half of a lymph node provided results similar to those of three-level histopathology. Clinical results indicate that the OSNA assay provides a useful intraoperative detection method of lymph node metastasis in breast cancer patients.

The E-cadherin gene is silenced by CpG methylation in human hepatocellular carcinomas

Our study was designed to clarify the significance of silencing the E‐cadherin gene, which is located on 16q22.1, due to CpG methylation during hepatocarcinogenesis. The CpG methylation status of primary hepatocellular carcinomas (HCCs) and corresponding liver tissues showing chronic hepatitis or cirrhosis, which are widely considered to be precancerous conditions, were assessed by digesting DNA with methylation‐sensitive and non‐sensitive restriction enzymes. CpG methylation around the promoter region of the E‐cadherin gene was detected in 46% of liver tissues showing chronic hepatitis or cirrhosis and 67% of HCCs examined. Immunohistochemical examination revealed reduced E‐cadherin expression in 59% of HCCs examined. CpG methylation around the promoter region correlated significantly with reduced E‐cadherin expression in HCCs (p < 0.05). CpG methylation around the promoter region, which increases during the progression from a precancerous condition to HCC, may participate in hepatocarcinogenesis through reduction of E‐cadherin expression, resulting in loss of intercellular adhesiveness and destruction of tissue morphology. Int. J. Cancer 71:355‐359, 1997.

Exosomes from bone marrow mesenchymal stem cells contain a microRNA that promotes dormancy in metastatic breast cancer cells

The bone marrow delivers dormancy signals in exosomes to metastatic cancer cells. Promoting Cancer Cell Dormancy with Exosomes Metastatic disease often develops long after treatment of the primary tumor because of cells that spread into metastatic niches, particularly the bone marrow. Because these “dormant” cells have a slow rate of cell cycling, they are not killed by traditional chemotherapies that target rapidly dividing cells. Ono et al. examined how cells present in the bone marrow niche trigger dormancy of metastatic breast cancer cells. They found that exosomes (vesicles shed by cells) from bone marrow–derived mesenchymal stem cells were taken up by cancer cells, in which they inhibited proliferation and promoted other characteristics associated with dormancy, in part through the delivery of a microRNA that suppressed the expression of a gene encoding a protein that promotes cell proliferation and motility. Thus, the bone marrow niche releases exosomes that deliver signals promoting metastatic cancer cell dormancy. Breast cancer patients often develop metastatic disease years after resection of the primary tumor. The patients are asymptomatic because the disseminated cells appear to become dormant and are undetectable. Because the proliferation of these cells is slowed, dormant cells are often unresponsive to traditional chemotherapies that exploit the rapid cell cycling of most cancer cells. We generated a bone marrow–metastatic human breast cancer cell line (BM2) by tracking and isolating fluorescent-labeled MDA-MB-231 cells that disseminated to the bone marrow in mice. Coculturing BM2 cells with bone marrow mesenchymal stem cells (BM-MSCs) isolated from human donors revealed that BM-MSCs suppressed the proliferation of BM2 cells, decreased the abundance of stem cell–like surface markers, inhibited their invasion through Matrigel Transwells, and decreased their sensitivity to docetaxel, a common chemotherapy agent. Acquisition of these dormant phenotypes in BM2 cells was also observed by culturing the cells in BM-MSC–conditioned medium or with exosomes isolated from BM-MSC cultures, which were taken up by BM2 cells. Among various microRNAs (miRNAs) increased in BM-MSC–derived exosomes compared with those from adult fibroblasts, overexpression of miR-23b in BM2 cells induced dormant phenotypes through the suppression of a target gene, MARCKS, which encodes a protein that promotes cell cycling and motility. Metastatic breast cancer cells in patient bone marrow had increased miR-23b and decreased MARCKS expression. Together, these findings suggest that exosomal transfer of miRNAs from the bone marrow may promote breast cancer cell dormancy in a metastatic niche.

Multicenter Phase II Study of Fertility-Sparing Treatment With Medroxyprogesterone Acetate for Endometrial Carcinoma and Atypical Hyperplasia in Young Women

PURPOSE To assess the efficacy of fertility-sparing treatment using medroxyprogesterone acetate (MPA) for endometrial carcinoma (EC) and atypical endometrial hyperplasia (AH) in young women. PATIENTS AND METHODS This multicenter prospective study was carried out at 16 institutions in Japan. Twenty-eight patients having EC at presumed stage IA and 17 patients with AH at younger than 40 years of age were enrolled. All patients were given a daily oral dose of 600 mg of MPA with low-dose aspirin. This treatment continued for 26 weeks, as long as the patients responded. Histologic change of endometrial tissue was assessed at 8 and 16 weeks of treatment. Either estrogen-progestin therapy or fertility treatment was provided for the responders after MPA therapy. The primary end point was a pathologic complete response (CR) rate. Toxicity, pregnancy rate, and progression-free interval were secondary end points. RESULTS CR was found in 55% of EC cases and 82% of AH cases. The overall CR rate was 67%. Neither therapeutic death nor irreversible toxicities were observed; however, two patients had grade 3 body weight gain, and one patient had grade 3 liver dysfunction. During the 3-year follow-up period, 12 pregnancies and seven normal deliveries were achieved after MPA therapy. Fourteen recurrences were found in 30 patients (47%) between 7 and 36 months. CONCLUSION The efficacy of fertility-sparing treatment with a high-dose of MPA for EC and AH was proven by this prospective trial. Even in responders, however, close follow-up is required because of the substantial rate of recurrence.

Comprehensive histologic analysis of ALK-rearranged lung carcinomas.

A subset (1% to 5%) of non-small-cell lung carcinomas harbors the EML4-ALK fusion gene. Data from previous studies on the histomorphology of ALK-rearranged lung cancer are inconsistent, and the specific histologic parameters that characterize this subset and how accurately such parameters predict underlying ALK abnormality remain uncertain. To answer these questions, we performed a comprehensive histologic analysis of 54 surgically resected, extensively sampled ALK-rearranged lung carcinomas and compared them with 100 consecutive resections of ALK-wild-type lung cancers. All 54 cases showed at least a focal adenocarcinoma component, and 3 and 2 cases had additional squamous and sarcomatoid differentiation, respectively. Solid or acinar growth pattern, cribriform structure, presence of mucous cells (signet-ring cells or goblet cells), abundant extracellular mucus, lack of lepidic growth, and lack of significant nuclear pleomorphism were more common in ALK-positive cancers. Two recognizable constellations of findings, a solid signet-ring cell pattern and a mucinous cribriform pattern, were present at least focally in the majority (78%) of ALK-positive tumors, but were rare (1%) in ALK-negative tumors. Multivariate analysis showed that a combination of these 2 patterns was the most powerful histologic indicator of ALK rearrangement. Characteristic histologies were present both in primary sites and in metastases. Thus, histologic findings may help to identify cases for ALK testing. However, none of the histologic parameters were completely sensitive or specific to ALK rearrangement, and histomorphology should not replace confirmatory molecular or immunohistochemical studies. ALK-positive cancers commonly showed coexpression of thyroid transcription factor-1 and p63, and its significance is currently unclear.

Large, central acellular zones indicating myoepithelial tumor differentiation in high-grade invasive ductal carcinomas as markers of predisposition to lung and brain metastases.

High-grade invasive ductal carcinomas (IDCs) of the breast with large, central acellular zones on their cut surfaces are usually associated with the myoepithelial immunophenotype of carcinoma cells, which includes the expression of S-100 protein, alpha-smooth muscle actin, and keratin 14. To clarify the clinical significance of these features of IDCs, the authors compared the incidence of the myoepithelial immunophenotype immunohistochemically, patient prognosis, and metastatic sites of the tumor between 20 high-grade IDCs with large, central acellular zones and 40 control high-grade IDCs without these zones. The myoepithelial immunophenotype was detected in 16 IDCs (80%) with large, central acellular zones but in only seven IDCs (18%) without. The risk ratio of metastasis, especially in the brain and lung, and death from cancer were significantly higher (p = 0.0096 and p = 0.030) for the 20 IDCs with large, central acellular zones than for those without by Coxs univariate analysis. Using Coxs multivariate analysis, large, central acellular zones in IDCs were an indicator of high risk of brain and lung metastases and of death by cancer independent of nodal status and tumor size. Examination of large, central acellular zones and myoepithelial immunophenotype in high-grade IDCs appears helpful in predicting patient prognosis and preferential metastatic sites of the tumors.

Conservative therapy for adenocarcinoma and atypical endometrial hyperplasia of the endometrium in young women: central pathologic review and treatment outcome.

Thirty-nine patients with endometrioid adenocarcinoma (EA) and atypical hyperplasia (AH) of the endometrium who received conservative treatment to preserve fertility were collected from member institutions of the Japan Gynecologic Oncology Study Group. Twenty-nine and ten were originally diagnosed with EA without myometrial invasion and AH, respectively. We performed a central pathological review to make definite diagnoses, and the diagnosis of EA in 29 cases was changed to AH in ten, complex hyperplasia in three and atypical polypoid adenomyoma in three, and AH in ten was changed to EA in one and simple hyperplasia in one. Nine of 12 women (75%) with EA and 15 of 18 women (83%) with AH had an initial response to medroxyprogesterone acetate (MPA) treatment. Two of nine responders with EA later developed relapse, and one of them had metastasis to the left obturator lymph node. Two became pregnant, and one delivered one full-term infant. One of the responders with AH had a relapse in the endometrium. Five became pregnant, and four delivered four normal infants. The young women with endometrial carcinoma localized in the endometrium who wish to preserve fertility may be treated as successfully with MPA as those with AH.

The correlation between cytoplasmic overexpression of epidermal growth factor receptor and tumor aggressiveness: poor prognosis in patients with pancreatic ductal adenocarcinoma.

Objectives: Recent studies have shown that some growth factor receptors with tyrosine kinase activity, eg, the epidermal growth factor receptor (EGFr) and the c-erbB-2 (HER-2) oncoprotein, are associated with aggressive biologic behavior of various cancer cell types. We examined the clinicopathological significance of the expression and localization of EGFr and HER-2 in both invasive and intraductal components of ductal adenocarcinomas of the pancreas. Methods: Tissue samples from 76 archival cases of pancreatic ductal adenocarcinoma were immunohistochemically analyzed for both membrane and cytoplasmic overexpression of EGFr and HER-2 oncoprotein. The rate of incidence between the invasive and intraductal components was analyzed and then their correlation with tumor differentiation and patient prognosis was analyzed. Results: Cytoplasmic EGFr overexpression was more frequent in invasive components (47 of 76, 62%) than in intraductal components (19 of 76, 25%), while membrane EGFr overexpression was more frequent in intraductal components (41 of 76, 54%) than in invasive components (11 of 76, 14%). The membrane HER-2 overexpression was also more frequent in intraductal components (15 of 76, 20%) than in invasive components (2 of 76, 3%), but the incidence of cytoplasmic HER-2 overexpression did not differ between intraductal components (12 of 76, 16%) and invasive components (8 of 76, 11%). The cytoplasmic EGFr overexpression in invasive components was more frequent in grade 3 group (32 of 33, 97%) than in grade 2 (15 of 32, 47%) and grade 1 groups (0 of 10, 0%) (P < 0.001). Patients with adenocarcinoma with cytoplasmic EGFr overexpression showed shorter overall survival than those with adenocarcinoma without cytoplasmic EGFr overexpression (P = 0.02). Conclusion: It is suggested that the cytoplasmic overexpression of EGFr plays a significant role in the progression of pancreatic ductal adenocarcinoma, especially in the invasion and acquisition of aggressive clinical behavior. Both membrane and cytoplasmic expression of HER-2 showed no significant correlation between tumor differentiation and poor survival.

Molecular Detection of Lymph Node Metastases in Breast Cancer Patients: Results of a Multicenter Trial Using the One-Step Nucleic Acid Amplification Assay

Purpose: Accurate assessment of metastasis in sentinel lymph nodes (SLN) of breast cancer is important but involves a heavy workload for the pathologist. We conducted a multicenter clinical trial in Japan to evaluate a new automated assay system for cytokeratin 19 mRNA, the one-step nucleic acid amplification (OSNA) assay (Sysmex), to detect lymph node metastasis of breast cancer. Experimental Design: Surgically obtained axillary lymph nodes were sectioned into four pieces, two of which were examined with the OSNA assay. The other two adjacent pieces were examined with H&E and immunohistochemical staining for cytokeratin 19. Serial sections at 0.2-mm intervals were used in trial 1 to determine the specificity of the OSNA assay, and three pairs of sections cut from the sliced surfaces of the pieces were used in trial 2 to compare the accuracy of the OSNA assay with that of a routine pathologic examination for SLNs in Japan. Results: In trial 1, the sensitivity and specificity were 95.0% [95% confidence interval (95% CI), 75.1-99.9%] and 97.1% (95% CI, 91.8-99.4%), respectively, for 124 axillary lymph nodes obtained from 34 patients. In trial 2, the agreement between findings of the assay and of the pathologic examination was 92.9% (95% CI, 90.1-95.1%) for 450 axillary lymph nodes obtained from 164 patients. Conclusion: The OSNA assay can detect lymph node metastasis as accurately as can conventional pathology and thus can be an effective addition to or alternative for rapid intraoperative examination of SLNs.