Chew n Wu

Mitochondrial DNA Mutations and Mitochondrial DNA Depletion in Breast Cancer

Somatic mutations in mitochondrial DNA (mtDNA) have been demonstrated in various tumors, including breast cancer. However, it still remains unclear whether the alterations in mtDNA are related to the clinicopathological features and/or the prognosis in the breast cancer. We analyzed somatic mutations in the D‐loop region, the common 4,977‐bp deletion, and the copy number of mtDNA in breast cancer and paired nontumorous breast tissues from 60 Taiwanese patients. We found that 18 of the 60 (30%) breast cancers displayed somatic mutations in mtDNA D‐loop region. The incidence of the 4,977‐bp deletion in nontumorous breast tissues (47%) was much higher than that in breast cancers (5%). The copy number of mtDNA was significantly decreased in 38 of the 60 (63%) breast cancers as compared to their corresponding nontumorous breast tissues (P = 0.0008). The occurrence of D‐loop mutations was associated with an older onset age (≥50 years old, P = 0.042), and tumors that lacked expressions of estrogen receptor and progesterone receptor (P = 0.024). Patients with mtDNA D‐loop mutation and breast cancer had significantly poorer disease‐free survival than those without mutation, when assessed by Kaplan–Meier curves and log‐rank test (P = 0.005). Multivariate Cox regression analysis indicated that a D‐loop mutation is a significant marker that is independent of other clinical variables and that it can be used to assess the prognosis of patients. Our findings suggest that somatic mutations in mtDNA D‐loop can be used as a new molecular prognostic indicator in breast cancer.

Mitochondrial genome instability and mtDNA depletion in human cancers.

Abstract: An increase in the rate of glycolysis is one of the metabolic alterations in most cancer cells. However, the role of alterations in mitochondrial function and mitochondrial DNA (mtDNA) in carcinogenesis still remains unclear. In this study, we analyzed the nucleotide sequence of the D‐loop and the copy number of mtDNA in 54 hepatocellular carcinomas (HCCs), 31 gastric, 31 lung, and 25 colorectal cancers as well as their corresponding non‐tumorous tissues. The results revealed that 42.6% (23/54) of the HCCs, 51.6% (16/31) of the gastric cancers, 22.6% (7/31) of the lung cancers, and 40.0% (10/25) of the colorectal cancers harbored mutation(s) in the D‐loop of mtDNA. The mtDNA mutations in 43.5% (10/23) of the HCCs, 62.5% (10/16) of the gastric cancers, 57.1% (4/7) of the lung cancers, and 90.0% (9/10) of the colorectal cancers were changes in the mononucleotide or dinucleotide repeats, deletions, or multiple insertions. Moreover, we found that there is a significant decrease in mtDNA copy number in 57.4% (31/54) of the HCCs, 54.8% (17/31) of the gastric cancers, 22.6% (7/31) of the lung cancers, and 28.0% (7/25) of the colorectal cancers compared with the corresponding non‐tumorous tissues. It is noteworthy that the incidence of somatic mutations in the D‐loop of mtDNA in the cancers of later stages was higher than that of the early‐stage cancers. Taken together, our findings suggest that instability in the D‐loop region of mtDNA, together with the decrease in mtDNA copy number, is involved in the carcinogenesis of human cancers.

Incidence and factors associated with recurrence patterns after intended curative surgery for gastric cancer

Recurrence after curative resection for gastric cancer remains high. We examined its incidence and factors related to recurrence pattern, while trying to avoid the interaction of various factors. A total of 611 gastric cancer patients after resection for curative intent (1988–1995) were analyzed. The result showed that 245 patients had recurrence (40.1%). Cumulative recurrence rates were 53.5%, 80%, 89.0%, 94.7%, 96.3%, 98%, and 99.5% at 1, 2, 3, 4, 5, 6, and 7 years, respectively. Over half of patients with recurrence (123; 50.2%) had an initial single recurrence. Taking single and multiple recurrence together, most recurrences (213; 86.9%) were distant metastases, 110 recurrences (44.9%) were local relapses, and 78 recurrences (49.8%) were both local and distant. Among the distant metastases, 131 patients (53.5%) had peritoneal dissemination, 106 patients (43.3%) had hematogenous metastases, and 70 patients (28.6%) had distant lymphatic spread. Scirrhous-type stromal reaction, serosa invasion, and female gender were factors negatively related to peritoneal recurrence. Medullary-type stromal reaction and male gender showed a preference for locoregional recurrence, and expanding growth tumor commonly led to hematogenous metastasis. Patients who had paraaortic lymph node metastasis were at high risk of developing distant lymphatic recurrence. It is conceivable that the patterns of recurrence and the times to recurrence provide a biological basis for clinical monitoring of patients with the aim of modifying therapeutic modalities.

Initial Experience of Robotic Gastrectomy and Comparison with Open and Laparoscopic Gastrectomy for Gastric Cancer

BackgroundRobotic gastrectomy has become more popular in the treatment of gastric cancer, especially in Asian countries. Until now, few studies have compared robotic surgery with open or laparoscopic surgery for gastric cancer patients.MethodsData were prospectively collected between January 2006 and February 2012. A total of 689 patients underwent curative resection of adenocarcinoma of the stomach. Patients were separated into three groups according to the different surgical approaches used (586 open, 64 laparoscopic, and 39 robotic). The clinicopathological characteristics and surgical outcomes of the three groups were compared.ResultsThe open group was associated with a larger tumor size, more D2 dissection, more advanced tumor stage, and more blood loss than the groups treated with laparoscopic and robotic methods. Robotic gastrectomy was associated with female predominance, less blood loss, shorter hospital stay, and longer operative time than open and laparoscopic gastrectomy. The retrieved lymph node numbers were similar between the open and robotic groups. Postoperative morbidity rates were similar among the three groups. In terms of the learning curve of robotic gastrectomy, operative time and docking time were significantly reduced in the recent robotic group (n = 14) compared to the initial robotic group (n = 25).ConclusionRobotic gastrectomy could achieve extended lymph node dissection similar to open surgery. Our results showed a significant learning curve effect in the initial 25 cases of the robotic group.

Aberrant methylation of Reprimo in human malignancies

Reprimo is a new candidate mediator of p53‐mediated cell cycle arrest at the G2 phase. Loss of Reprimo gene expression accompanied by its promoter methylation was identified in pancreatic and lung cancers. Our aim was to examine the methylation status of Reprimo in a broad range of cancers. We examined Reprimo expression by RT‐PCR and the DNA methylation status of the Reprimo promoter by MSP in 39 tumor cell lines. Loss or downregulation of Reprimo expression was frequent (62%), and we confirmed that transcriptional repression of Reprimo was caused by hypermethylation (overall concordance 92%). Treatment of expression‐negative cells with 5‐aza‐2′‐deoxycytidine restored Reprimo expression. We then examined aberrant methylation of Reprimo in 645 tumors representing 16 tumor types. Promoter methylation of Reprimo was found in 79% of gastric cancers, 62% of gallbladder cancers, 57% of lymphomas, 56% of colorectal cancers, 40% of esophageal adenocarcinomas, 37% of breast cancers and 31% of leukemias. Methylation frequencies in ovarian cancers, bladder cancers, cervical cancers, brain tumors, malignant mesotheliomas and pediatric tumors were lower (0–20%). Reprimo methylation was rarely detected in nonmalignant tissues (0–11%) except for gastric epithelia. While colorectal polyps were also frequently methylated (27%), chronic cholecystitis samples were infrequently methylated (4%). Furthermore, we failed to identify Reprimo mutation in colorectal and gastric cancer cell lines and 50 primary colorectal cancers. Aberrant methylation of Reprimo with loss of expression is a common event and may contribute to the pathogenesis of some types of human malignancy.

Tyrosine kinases and gastric cancer

Carcinoma of the stomach is one of the most prevalent cancer types in the world today. Two major forms of gastric cancer are distinguished according to their morphological and clinicopathological classifications (well differentiated/intestinal type and poorly differentiated/diffuse type), characteristics that could also be attributed to the altered expression of different types of oncogenes or tumor suppressor genes. Significant differences exist for gastric cancer incidence comparing people of different ethnic origins, implicating various genetic and epigenetic factors for gastric oncogenesis. There are only a limited number of molecular markers available for gastric cancer detection and prognostic evaluation, among which are tyrosine kinases. There is convincing evidence that tyrosine kinases are involved in oncogenesis and disease progression for many human cancers. Amplifications of certain tyrosine kinases (c-met, k-sam and erbB2/neu) have been associated with human gastric cancer progression. Alternatively spliced transcripts and enhanced protein-expression levels for some of these tyrosine kinases are correlated with clinical outcomes for gastric cancer patients. With advent of high throughput techniques, it is now possible to detect nearly all expressed tyrosine kinases in a single screen. This increases the chance to identify additional tyrosine kinases as predictive markers for gastric cancers. In this article, we will first review the literature data concerning certain tyrosine kinases implicated in gastric carcinogenesis and then summarize more recent work which provide comprehensive tyrosine kinase profiles for gastric cancer specimens and cell lines. Two new gastric cancer molecular markers (tie-1 and mkk4) have been identified through the use of these profiles and demonstrated effective as clinical prognostic indicators.

Quality of life after curative gastrectomy for gastric cancer in a randomised controlled trial

Quality of life (QOL) was studied in gastric cancer patients treated on a randomised, controlled trial comparing D1 (level 1) with D3 (levels 1, 2 and 3) lymphadenectomy. A total of 221 patients were randomly assigned to D1 (n=110) and D3 (n=111) surgery. Quality-of-life assessments included functional outcomes (a 14-item survey about treatment-specific symptoms) and health perception (Spitzer QOL Index) was performed before and after surgery at disease-free status. Patients suffered from irrelative events such as loss of partners was excluded thereafter. Main analyses were done by intention-to-treat. Thus, 214 D1 (106/110=96.4%) and D3 (108/111=97.3%) R0 patients were assessed. Longitudinal analysis showed that functional outcomes decreased at 6 months after surgery and increased over time thereafter, while health perceptions increased over time in general. On the basis of linear mixed model analyses, patients having total gastrectomy, advanced cancer and hemipancreaticosplenectomy, but not complications had poorer QOL than those without. D1 and D3 patients showed no significant difference in QOL. The results suggest that changes of QOL were largely due to scope of gastric resection, disease status and distal pancreaticosplenectomy, rather than the extent of lymph node dissection. This indicates that nodal dissection can be performed for a potentially curable gastric cancer.

Expression and up-regulation of interleukin-6 in oesophageal carcinoma cells by n-sodium butyrate

SummaryRecently, the serum level of interleukin (IL)-6 has been shown to correlate with disease progression and prognosis of cancer patients. However, the available information about the source and the pathophysiological regulation of IL-6 in cancer cells is limited. Thus, in this study, we tried to identify the source and the clinical roles of serum IL-6 in patients with oesophageal squamous cell carcinoma (ESCC), and then further to characterize the biological regulation of IL-6 in ESCC cell lines. Sera and tissue specimens from 80 consecutive patients with ESCC were collected between 1993 and 1997. Additionally, three ESCC cell lines were used for in vitro study. The concentration of serum IL-6 was measured by enzyme-linked immunosorbent assay (ELISA), and correlated the survival time with measured IL-6 level. Expressions of IL-6, IL-6Rα (IL-6 receptor alpha) and gp130 in pathological sections and cell lines were characterized by immunological staining. Detection of IL-6 mRNA was determined by in situ hybridization (ISH) and reverse transcription-polymerase chain reaction (RT-PCR). Up-regulation of IL-6 by n-sodium butyrate (n-BT) was studied in ESCC cell lines. The levels of serum IL-6 in patients with ESCC were significantly higher than those in the healthy controls. Serum levels of IL-6 were also shown to correlate with disease progression and survival. However, sCD8 levels and lymphocyte counts in the peripheral blood were not parallel to the changed pattern of serum IL-6. In pathological sections and ESCC cell lines, message of IL-6 was identified by ISH in cancer cells. Expression of IL-6 mRNA was further confirmed with RT-PCR in ESCC cell lines. Although IL-6 was detected in some ESCC cell lines, IL-6 gene expression and protein production could be induced or enhanced by n-BT treatment in all three cell lines. The serum levels of IL-6 are frequently elevated at diagnosis of ESCC, and are associated with poor prognosis. IL-6 that could be produced by cancer cells is up-regulated by n-BT.

Surgical results of early gastric cancer and proposing a treatment strategy

BackgroundPrognosis for patients with early gastric cancer after surgical resection is excellent. The 5-year or even 10-year survival is more than 90%. In the present study, we investigated the result of treating early gastric cancer surgically in our hospital, with special reference to the risk factor(s) for tumor recurrence and the relationship between age and survival.Patients and MethodsFrom January 1988 to December 2002, a total of 479 patients with early gastric cancer underwent resection by our surgeons. Results of preoperative studies, operative findings, histopathology and postoperative follow-up were recorded respectively, and the postoperative disease-related survival, overall survival, tumor recurrence and recurrent patterns were analyzed. The clinicopathological factors were also analyzed to identify the risk factor(s) related to tumor recurrence.ResultsOlder patients (>75 years old) had a poorer overall survival than younger patients. However, the disease-related survival was not significantly different between the two. Recurrence was observed in 21 patients, the most important factor of which was lymph node status. Lymph node metastases occurred in 54 patients (11.3%)—coming from mucosal tumors in 12 patients (4.4%) and from submucosal tumors in 42 (20.3%). When the size of the mucosal tumor was smaller than 1 cm, no lymph node metastasis was found in our patients.ConclusionsThe most important risk factor of recurrence in early gastric cancer is lymph node status. Given the low probability of lymph node metastasis and recurrence in tumors less than 1 cm in diameter limited to the mucosa, more limited surgery maybe appropriate in these carefully selected instances.

2-Methoxyestradiol attenuates phosphatidylinositol 3-kinase/Akt pathway-mediated metastasis of gastric cancer

The major obstacle for the treatment of gastric cancer is recurrence and metastasis; yet, its molecular mechanism is largely unknown. 2‐methoxyestradiol (2‐ME), a metabolite of the estradiol‐17β, has recently been demonstrated to have multifactorial effects against tumor proliferation and angiogenesis; how these effects are interrelated and act cooperatively is the key question to be elucidated. Akt activation was shown to promote cancer cell invasiveness, and inhibition of Akt phosphorylation by 2‐ME was also noted. We herein investigated the significance of PI3K/Akt activation in gastric cancer metastasis and the anti‐metastatic effect of 2‐ME through attenuation of Akt activity. Immunohistochemistry of PI3K, phosphorylated Akt (p‐Akt) and phosphorylated Erk (p‐Erk) was performed in tumors from 56 gastric cancer patients, and a significant correlation between PI3K/p‐Akt and tumor stage/prognosis was demonstrated (p < 0.05). An in vitro study of 7 gastric cancer cell lines showed a remarkable correlation between PI3K and p‐Akt. PI3K/p‐Akt overexpression was associated with invasiveness/migration; in contrast, phosphorylation of Erk was not shown to be correlated with invasiveness. In addition, metastatic gastric cancer clones expressed a higher level of PI3K/p‐Akt. The anti‐metastatic effect of a low dose of 2‐ME and inactivation of Akt was demonstrated. 2‐ME also exhibited an ability to inhibit gastric cancer cell proliferation and induce G2/M cell cycle arrest at a higher concentration than that required for inhibition of migration. We conclude that the activation of PI3K/Akt pathway is involved in the late‐stage progression and metastasis of gastric cancer, and attenuation of p‐Akt by 2‐ME suppresses metastasis.