Hideo Baba

CD44 Variant Regulates Redox Status in Cancer Cells by Stabilizing the xCT Subunit of System xc− and Thereby Promotes Tumor Growth

CD44 is an adhesion molecule expressed in cancer stem-like cells. Here, we show that a CD44 variant (CD44v) interacts with xCT, a glutamate-cystine transporter, and controls the intracellular level of reduced glutathione (GSH). Human gastrointestinal cancer cells with a high level of CD44 expression showed an enhanced capacity for GSH synthesis and defense against reactive oxygen species (ROS). Ablation of CD44 induced loss of xCT from the cell surface and suppressed tumor growth in a transgenic mouse model of gastric cancer. It also induced activation of p38(MAPK), a downstream target of ROS, and expression of the gene for the cell cycle inhibitor p21(CIP1/WAF1). These findings establish a function for CD44v in regulation of ROS defense and tumor growth.

Epithelial–mesenchymal transition in cancer development and its clinical significance

The epithelial–mesenchymal transition (EMT) plays a critical role in embryonic development. EMT is also involved in cancer progression and metastasis and it is probable that a common molecular mechanism is shared by these processes. Cancer cells undergoing EMT can acquire invasive properties and enter the surrounding stroma, resulting in the creation of a favorable microenvironment for cancer progression and metastasis. Furthermore, the acquisition of EMT features has been associated with chemoresistance which could give rise to recurrence and metastasis after standard chemotherapeutic treatment. Thus, EMT could be closely involved in carcinogenesis, invasion, metastasis, recurrence, and chemoresistance. Research into EMT and its role in cancer pathogenesis has progressed rapidly and it is now hypothesized that novel concepts such as cancer stem cells and microRNA could be involved in EMT. However, the involvement of EMT varies greatly among cancer types, and much remains to be learned. In this review, we present recent findings regarding the involvement of EMT in cancer progression and metastasis and provide a perspective from clinical and translational viewpoints. (Cancer Sci 2009)

Randomized Phase III Study of Gemcitabine Plus S-1, S-1 Alone, or Gemcitabine Alone in Patients With Locally Advanced and Metastatic Pancreatic Cancer in Japan and Taiwan: GEST Study

PURPOSE The present phase III study was designed to investigate the noninferiority of S-1 alone and superiority of gemcitabine plus S-1 compared with gemcitabine alone with respect to overall survival. PATIENTS AND METHODS The participants were chemotherapy-naive patients with locally advanced or metastatic pancreatic cancer. Patients were randomly assigned to receive only gemcitabine (1,000 mg/m(2) on days 1, 8, and 15 of a 28-day cycle), only S-1 (80, 100, or 120 mg/d according to body-surface area on days 1 through 28 of a 42-day cycle), or gemcitabine plus S-1 (gemcitabine 1,000 mg/m(2) on days 1 and 8 plus S-1 60, 80, or 100 mg/d according to body-surface area on days 1 through 14 of a 21-day cycle). RESULTS In the total of 834 enrolled patients, median overall survival was 8.8 months in the gemcitabine group, 9.7 months in the S-1 group, and 10.1 months in the gemcitabine plus S-1 group. The noninferiority of S-1 to gemcitabine was demonstrated (hazard ratio, 0.96; 97.5% CI, 0.78 to 1.18; P < .001 for noninferiority), whereas the superiority of gemcitabine plus S-1 was not (hazard ratio, 0.88; 97.5% CI, 0.71 to 1.08; P = .15). All treatments were generally well tolerated, although hematologic and GI toxicities were more severe in the gemcitabine plus S-1 group than in the gemcitabine group. CONCLUSION Monotherapy with S-1 demonstrated noninferiority to gemcitabine in overall survival with good tolerability and presents a convenient oral alternative for locally advanced and metastatic pancreatic cancer.

Clinical significance of occult micrometastasis in lymph nodes from patients with early gastric cancer who died of recurrence

BACKGROUND Even after curative resection of an early gastric cancer, some patients die of a recurrence. It is our view that patients with early gastric cancer who died of their disease had occult micrometastases in perigastric lymph nodes at the time of the original diagnosis. In an attempt to identify these micrometastases, lymph nodes dissected from early gastric cancer lesions were stained after operation with monoclonal antibody against cytokeratin, an essential constituent of the cytoskeleton of epithelial cells. METHODS The 420 dissected lymph nodes from 34 patients with node-negative early gastric cancer who died of a recurrence were examined for the presence of tumor cells. We used immunocytochemical techniques and an antiserum to epithelial membrane antigen. The monoclonal antibody CAM 5.2 recognizes cytokeratin polypeptides (human cytokeratin numbers 8 and 18) commonly present in epithelial cells. Clinicopathologic characteristics and prognosis were determined for patients with cytokeratin-positive cells in the lymph nodes. RESULTS. Of 420 lymph nodes, 15 (3.6%) nodes and 23.5% (8 of 34) of the patients presented with cytokeratin-positive cells at the time of primary operation. The presence of cytokeratin positivity was not related to various clinicopathologic factors. The histologic stage of eight cytokeratin-positive cases was upstaged by the group of cytokeratin-positive lymph nodes from stage I to three of stage II, four of stage III, and one of stage IV, hematogenous recurrences were common, and the prognosis was poorer. CONCLUSIONS Immunohistochemical techniques aid in identifying micrometastatic disease in lymph nodes missed in routine hematoxylin-eosin staining. Cytokeratin staining of the dissected lymph nodes is recommended to precisely determine tumor stage and prognosis for patients with early gastric cancer.

MicroRNA-21 Regulates the Proliferation and Invasion in Esophageal Squamous Cell Carcinoma

Purpose: MicroRNAs are ∼22 nucleotide noncoding RNA molecules that posttranscriptionally regulate gene expression. The aim of this study was (a) to determine a role of microRNA-21 in esophageal squamous cell carcinoma and (b) to elucidate the regulation of the programmed cell death 4 (PDCD4) gene by microRNA-21. Experimental Design: MicroRNA-21 expression was investigated in 20 matched normal esophageal epitheliums and esophageal squamous cell carcinomas and seven esophageal squamous cell carcinoma cell lines (TE6, TE8, TE10, TE11, TE12, TE14, KYSE30) by TaqMan quantitative real-time PCR and in situ hybridization. To evaluate the role of microRNA-21, cell proliferation and invasion were analyzed with anti–microRNA-21–transfected cells. In addition, the regulation of PDCD4 by microRNA-21 was elucidated to identify the mechanisms of this regulation. Results: Of 20 paired samples, 18 cancer tissues overexpressed microRNA-21 in comparison with matched normal epitheliums. Specifically, patients with lymph node metastasis or venous invasion showed significantly high expression of microRNA-21. In situ hybridization for microRNA-21 showed strong positive staining in paraffin-embedded esophageal squamous cell carcinoma tissues. All seven esophageal squamous cell carcinoma cell lines also overexpressed microRNA-21, and anti–microRNA-21–transfected cells showed significant reduction in cellular proliferation and invasion. The PDCD4 protein levels in esophageal squamous cell carcinoma cells have an inverse correlation with microRNA-21 expression. Anti–microRNA-21–transfected cells increased PDCD4 protein expression without changing the PDCD4 mRNA level and increased a luciferase-reporter activity containing the PDCD4-3′ untranslated region construct. Conclusions: MicroRNA-21 targets PDCD4 at the posttranscriptional level and regulates cell proliferation and invasion in esophageal squamous cell carcinoma. It may serve as a novel therapeutic target in esophageal squamous cell carcinoma.

Clinical impact of serum exosomal microRNA‐21 as a clinical biomarker in human esophageal squamous cell carcinoma

Exosomes are 40‐nm to 100‐nm membrane vesicles that are secreted by various cells, and they play a major role in cell‐cell communication. The objective of this study was to clarify the significance of the levels of microRNA in exosomes extracted from the sera of patients with esophageal squamous cell cancer (ESCC).

Identification of HLA-A2- or HLA-A24-Restricted CTL Epitopes Possibly Useful for Glypican-3-Specific Immunotherapy of Hepatocellular Carcinoma

Purpose and Experimental Design: We previously reported that glypican-3 (GPC3) was overexpressed, specifically in hepatocellular carcinoma (HCC) and melanoma in humans, and it was useful as a novel tumor marker. We also reported that the preimmunization of BALB/c mice with dendritic cells pulsed with the H-2Kd-restricted mouse GPC3298-306 (EYILSLEEL) peptide prevented the growth of tumor-expressing mouse GPC3. Because of similarities in the peptide binding motifs between H-2Kd and HLA-A24 (A*2402), the GPC3298-306 peptide therefore seemed to be useful for the immunotherapy of HLA-A24+ patients with HCC and melanoma. In this report, we investigated whether the GPC3298-306 peptide could induce GPC3-reactive CTLs from the peripheral blood mononuclear cells (PBMC) of HLA-A24 (A*2402)+ HCC patients. In addition, we used HLA-A2.1 (HHD) transgenic mice to identify the HLA-A2 (A*0201)–restricted GPC3 epitopes to expand the applications of GPC3-based immunotherapy to the HLA-A2+ HCC patients. Results: We found that the GPC3144-152 (FVGEFFTDV) peptide could induce peptide-reactive CTLs in HLA-A2.1 (HHD) transgenic mice without inducing autoimmunity. In five out of eight HLA-A2+ GPC3+ HCC patients, the GPC3144-152 peptide-reactive CTLs were generated from PBMCs by in vitro stimulation with the peptide and the GPC3298-306 peptide-reactive CTLs were also generated from PBMCs in four of six HLA-A24+ GPC3+ HCC patients. The inoculation of these CTLs reduced the human HCC tumor mass implanted into nonobese diabetic/severe combined immunodeficiency mice. Conclusion: Our study raises the possibility that these GPC3 peptides may therefore be applicable to cancer immunotherapy for a large number of HCC patients.

Akt is frequently activated in HER2/neu-positive breast cancers and associated with poor prognosis among hormone-treated patients.

Akt/PKB is a serine/threonine kinase that plays an important role in survival when cells are exposed to different apoptotic stimuli. Aberrant activation of Akt/PKB in breast carcinoma is associated with poor prognosis and resistance to endocrine therapy and chemotherapy. The Akt signaling pathway currently attracts considerable attention as a new target for effective therapeutic strategies. We therefore investigated the relationship between activation of Akt and clinicopathologic variables including hormone receptor and HER2/neu status. Breast cancer tissues obtained from 252 patients were utilized for this study. We evaluated Akt activation by immunohistochemical assessment of the expression of phosphorylated Akt (pAkt) at Ser‐473. Eighty‐four cases (33.3%) were diagnosed as positive for pAkt expression. pAkt was significantly associated with HER2/neu overexpression (p < 0.0001). There was an inverse correlation between pAkt and PR expression (p = 0.0321); however, there was no association between pAkt and ER expression. Survival analysis showed that pAkt positivity was associated with poor disease‐free survival in cases with postoperative hormone therapy; however, there was no association in cases without hormone therapy. Our results indicate that Akt activation induced poor prognosis in patients who received adjuvant hormone therapy. This finding suggests that inhibition of the Akt signaling pathway may increase the efficacy of hormone therapy and improve the prognosis of patients who receive adjuvant hormone therapy.

Irinotecan plus S-1 (IRIS) versus fluorouracil and folinic acid plus irinotecan (FOLFIRI) as second-line chemotherapy for metastatic colorectal cancer: a randomised phase 2/3 non-inferiority study (FIRIS study)

BACKGROUND Fluorouracil and folinic acid with either oxaliplatin (FOLFOX) or irinotecan (FOLFIRI) are widely used as first-line or second-line chemotherapy for metastatic colorectal cancer. However, infusional fluorouracil-based regimens, requiring continuous infusion and implantation of an intravenous port system, are inconvenient. We therefore planned an open-label randomised controlled trial to verify the non-inferiority of irinotecan plus oral S-1 (a combination of tegafur, 5-chloro-2,4-dihydroxypyridine, and potassium oxonate; IRIS) to FOLFIRI as second-line chemotherapy for metastatic colorectal cancer. METHODS Between Jan 30, 2006, and Jan 29, 2008, 426 patients with metastatic colorectal cancer needing second-line chemotherapy from 40 institutions in Japan were randomly assigned by a computer-based minimisation method to receive either FOLFIRI (n=213) or IRIS (n=213). In the FOLFIRI group, patients received folinic acid (200 mg/m(2)) and irinotecan (150 mg/m(2)) and then a bolus injection of fluorouracil (400 mg/m(2)) on day 1 and a continuous infusion of fluorouracil (2400 mg/m(2)) over 46 h, repeated every 2 weeks. In the IRIS group, patients received irinotecan (125 mg/m(2)) on days 1 and 15 and S-1 (40-60 mg according to body surface area) twice daily for 2 weeks, repeated every 4 weeks. The primary endpoint was progression-free survival, with a non-inferiority margin of 1.333. Statistical analysis was on the basis of initially randomised participants. This study is registered with ClinicalTrials.gov, number NCT00284258. FINDINGS All randomised patients were included in the primary analysis. After a median follow-up of 12.9 months (IQR 11.5-18.2), median progression-free survival was 5.1 months in the FOLFIRI group and 5.8 months in the IRIS group (hazard ratio 1.077, 95% CI 0.879-1.319, non-inferiority test p=0.039). The most common grade three or four adverse drug reactions were neutropenia (110 [52.1%] of 211 patients in the FOLFIRI group and 76 [36.2%] of 210 patients in the IRIS group; p=0.0012), leucopenia (33 [15.6%] in the FOLFIRI group and 38 [18.1%] in the IRIS group; p=0.5178), and diarrhoea (ten [4.7%] in the FOLFIRI group and 43 [20.5%] in the IRIS group; p<0.0001). One treatment-related death from hypotension due to shock was reported in the FOLFIRI group within 28 days after the end of treatment; no treatment-related deaths were reported in the IRIS group. INTERPRETATION Progression-free survival with IRIS is not inferior to that with FOLFIRI in patients receiving second-line chemotherapy for metastatic colorectal cancer. Treatment with IRIS could be an additional therapeutic option for second-line chemotherapy in metastatic colorectal cancer. FUNDING Taiho Pharmaceutical Co Ltd and Daiichi Sankyo Co Ltd.

Lymphadenectomy for cure in patients with early gastric cancer and lymph node metastasis

The anatomic distribution, size, and histologic mode of involvement of 98 metastatic lymph nodes in 49 of 370 patients were examined to determine to what extent lymphadenectomy should be performed in addition to gastrectomy in patients with early gastric cancer. Nodal involvement in the marginal sinus (30 nodes) and partial medullary sinus (37 nodes) were commonly seen, and the lymph nodes of those types were enlarged compared with 1,086 patients with no metastatic lymph nodes (control group). Lymph nodes of the wide medullary sinus (11 nodes), small nodule (3 nodes), and massive involvement types (17 nodes) did not enlarge compared with those of the other types and those of the control group. Most of the metastatic sites (76.6 percent) were in the perigastric lymph nodes along the lesser and greater curvatures, about a fifth were in the extraperigastric nodes along the left gastric, common hepatic, celiac, and splenic arteries, and the least were in the extraperigastric nodes (3.1 percent) along the hepatoduodenal ligament. Since the rate of macroscopic diagnosis during operation was so poor, regardless of the histologic modes of nodal involvement, and also in cases of metastatic lymph nodes less than 15 mm in widest diameter, for curative operation of patients with early gastric cancer, perigastric and extraperigastric lymph nodes along the main arteries near the stomach should be completely dissected, in addition to resection of the stomach.