Atsushi Sasaki

Cancer stem cells in human gastrointestinal cancers.

The concept of cancer stem cell has developed in leukemia. Recently, it has expanded to include solid tumors such as brain or breast tumors. However, the descriptions are not recognized in human gastrointestinal cancers. We used flow cytometry and the DNA-binding dye (Hoechst 33342) to isolate side population (SP) cells from various human gastrointestinal system cancer cell lines. The SP cell fraction is considered to contain abundant stem cells. Fifteen of 16 cancer cell lines from the gastrointestinal system contained 0.3–2.2% SP cells. We studied the characteristics of the SP cells in hepatic or colon cancer cell lines. The results demonstrated that cancers of the gastrointestinal system do contain SP cells that show some characters of so-called stem cells. In this paper, we report our study results with a review of the literature.

Reduced tau expression in gastric cancer can identify candidates for successful Paclitaxel treatment

A recent study disclosed that breast cancer cases with low ‘tau’ expression can predict susceptibility to Paclitaxel administration. In the current study, the clinical significance of tau expression in gastric cancer cases was established by identifying candidates with Paclitaxel administration. Tissue specimens from 20 cases of in-operable or noncuratively resected gastric cancer were examined. Subsequent to the administration of 80u2009mgu2009m−2 of Paclitaxel in six 3-h intravenous infusions, the clinical effectiveness of Paclitaxel was evaluated by the size of metastatic lesions with computed tomography. The status of the tau expression was determined by immunohistochemistry. Based on a previously reported classification scheme, six were classified as tau-negative expression (0, 1+) cases and 14 were classified as tau-positive expression (2+, 3+) cases. All six (100%) cases of tau-negative expression showed a favourable response (partial response or minor response) to Paclitaxel administration. However, 12 (86%) of the 14 cases of tau-positive expression showed progressive disease (n=11) or no change (n=1) after Paclitaxel administration. The serum carcinoembryonic antigen values of the six cases of tau-negative expression were markedly decreased in comparison to the 14 tau-positive cases. These data indicate that tau-negative expression can be used to select gastric cancer patients, which will favourably respond to Paclitaxel treatment.

Improved long-term survival after liver resection for hepatocellular carcinoma in the modern era: retrospective study from HCV-endemic areas.

It remains unclear whether recent progress in perioperative management and treatment for recurrent hepatocellular carcinoma (HCC) has improved patient outcomes in hepatitis C virus-endemic areas. The clinicopathologic and follow-up data of 218 consecutive HCC patients who underwent curative resection between 1982 and 2003 were analyzed. Patients were assigned to one of two groups: before 1992 (early group; n = 82) and 1992 and later (late group; n = 136). Factors influencing survival rates were investigated by multivariate analysis. The effects of the period during which the hepatic resection was done on the patients’ outcome were examined with respect to tumor size. The 5-year cancer-related and disease-free survival rates were 51.4% and 20.4%, respectively. The late group showed better 5-year cancer-related survival than the early group (64.1% vs. 33.8%), but disease-free survival did not differ significantly between the groups. On multivariate analysis, the period of the hepatic resection was identified as an independent prognostic factor for cancer-related survival (relative risk 0.70, P < 0.01) but not disease-free survival. There were no differences in the cancer-related and disease-free survival rates between the two groups for patients with tumors ≤ 25 mm. In patients with HCCs > 50 mm, both cancer-related and disease-free survival rates were better in patients in the late group. During the past two decades, improvements in the treatment of recurrent HCC tumors have contributed to controlling large HCCs but not to controlling the multicentric development of HCCs. It may be important to control multicentric recurrence of HCC to improve patient survival in areas where the hepatitis C virus is endemic.

Receptor Activator of Nuclear Factor-κB Ligand (RANKL) Expression in Hepatocellular Carcinoma With Bone Metastasis

BackgroundAlthough receptor activator of nuclear factor-κB ligand (RANKL) seems to be involved in the development of bone metastases in several malignant tumors, its role in hepatocellular carcinoma (HCC) has not been investigated.MethodsWe retrospectively examined the immunohistochemical expression of RANKL in formalin-fixed, paraffin-embedded resected specimens obtained from 96 patients with HCC with (nxa0=xa016) and without (nxa0=xa080) bone metastases. In addition, tumor RANKL mRNA expression was evaluated by reverse transcriptase–polymerase chain reaction (RT-PCR) in five selected patients. We analyzed the relationship between RANKL expression level, bone metastasis development, and survival rate of patients with HCC after hepatic resection.ResultsOf the 96 patients with HCC, serum hepatitis C virus antibody was detected in 43.5% of patients and hepatitis B surface antigen in 29.5% of patients. Thirty-three patients (36.5%) also had liver cirrhosis. Immunohistochemical analysis showed that RANKL protein was present in 10 (62.5%) of 16 patients with HCC with bone metastasis compared with 21 (26.3%) of 80 patients with HCC without bone metastasis; we found that RANKL expression was statistically significantly correlated to bone metastasis development (Pxa0<xa0.01). RANKL mRNA expression was confirmed by RT-PCR in patients positive for RANKL protein expression by immunohistochemistry. The 5-year cancer-related (Pxa0<xa0.01) and disease-free survival (Pxa0<xa0.01) rates after hepatic resection were statistically significantly worse in patients positive for RANKL expression compared with RANKL-negative patients.ConclusionsSome HCC cells produced the crucial bone resorption regulator RANKL. Because RANKL modulates bone turnover, its presence would have profound implications for the establishment and development of bone metastases.

Opa Interacting Protein 5 (OIP5) Is a Novel Cancer-testis Specific Gene in Gastric Cancer

BackgroundIdentification of novel cancer-specific antigens is important for the advancement of immunotherapy. Our aim was to identify cancer-specific genes in gastric cancer.MethodsUsing cDNA microarray analysis, we detected genes overexpressed specifically in gastric cancer cells. The expression levels of selected genes, including OIP5, was confirmed by real time RT-PCR analysis in tumor/normal paired bulk samples of 58 clinical cases. The expression levels of selected genes in normal tissues were also determined with a human total RNA master panel. We also compared the expression status of OIP5 with that of the other known cancer-testis specific genes.ResultsTwenty-two genes were determined to be upregulated in gastric cancer cells. Among these, three genes (CDC6, Exo1, and OIP5) were selected and confirmed to be upregulated in the tumor tissue compared to normal tissue. A human total RNA master panel demonstrated that OIP5, but not Exo1 or CDC6, showed high specificity in testis. Thus OIP5 may be considered a cancer-testis specific gene. In 58 clinical cases of gastric cancer examined, we found OIP5 gene expression in 27 cases (47%). Thirteen of these 27 cases showed no expression of the known cancer specific genes such as MAGE-1, MAGE-3 or NY-ESO-1.ConclusionsUsing a combination of LMD and microarray, we identified OIP5 as a cancer-testis specific gene. Further expression analysis in a set of clinical cases revealed that OIP5 may be a novel immunotherapy target for patients with gastric cancer.

Loss of MAL expression in precancerous lesions of the esophagus.

BackgroundWe have identified a novel function of MAL (T-cell differentiation-related gene) as a candidate suppressor gene in esophageal cancer. As the role of MAL expression in esophageal carcinogenesis is as yet undetermined, MAL expression in a rat multi-step carcinogenic model and in precancerous lesions of the human esophagus was investigated. Microarray analysis between MAL-transfectant and control cells was also carried out to clarify how MAL confers its anti-tumor effects.Materials and Methods(1) In the rat model, MAL expression levels in laser microdissected normal esophageal epithelium, dysplastic tissues and carcinoma tissues were examined by reverse transcription (RT)-PCR. (2) Immunostaining with MAL antibody was performed in 10 dysplastic lesions adjacent to cancer in six cases of esophageal cancer. (3) We established a MAL transfectant using a Tet-off vector in esophageal cancer cells and performed microarray analysis under MAL-positive and MAL-negative conditions.Results(1) In the rat model, MAL mRNA expression was observed only in the normal samples. (2) MAL expression was observed distinctively in differentiated or keratinized normal tissues and was not observed in either dysplastic lesions or carcinoma tissue. (3) Up-regulated genes in MAL-positive cells included keratin 18 (transfectant/controlxa0=xa02.94) and keratin 10 (t/cxa0=xa02.82).ConclusionMAL expression was lost in dysplastic lesions of the rat carcinoma model as well as the human esophagus. The up-regulated keratins revealed by microarray analysis and the strong staining of the differentiated normal tissues in immunohistochemical study support the role of MAL as a regulator of differentiation in esophageal epithelium.