Suppression of actopaxin impairs hepatocellular carcinoma metastasis through modulation of cell migration and invasion

Early reports suggested that actopaxin, a member of the focal adhesion proteins, regulates cell migration. Here we investigated whether actopaxin is involved in hepatocellular carcinoma (HCC) progression and metastasis. We examined actopaxin expression in human HCC samples using immunohistochemistry and western blotting. The functional and molecular effect of actopaxin was studied in vitro by overexpression in a nonmetastatic HCC cell line, as well as repression in a metastatic cell line. The in vivo effect of actopaxin repression was studied in nonobese diabetic and severe combined immunodeficient mice. We found that actopaxin was frequently overexpressed in human HCC patients and its overexpression positively correlated with tumor size, stage, and metastasis. Actopaxin expression also correlated with the metastatic potential of HCC cell lines. Actopaxin overexpression induced the invasion and migration ability of nonmetastatic HCC cells, whereas down-regulation of actopaxin reverted the invasive phenotypes and metastatic potential of metastatic HCC cells through regulating the protein expression of certain focal adhesion proteins including ILK, PINCH, paxillin, and cdc42, as well as regulating the epithelial-mesenchymal transition pathway. Furthermore, there was a close association between actopaxin and CD29. HCC cells with stronger CD29 expression showed a higher actopaxin level, whereas actopaxin repression attenuated CD29 activity. Finally, actopaxin down-regulation enhanced the chemosensitivity of HCC cells towards oxaliplatin treatment by way of a collective result of suppression of survivin protein, β-catenin, and mammalian target of rapamycin pathways and up-regulation of p53.

CONCLUSION

This study provides concrete evidence of a significant role of actopaxin in HCC progression and metastasis, by way of regulation of cell invasiveness and motility, an epithelial-mesenchymal transition process, and chemosensitivity to cytotoxic drugs.

Identification of CD44+ cancer stem cells in human gastric cancer

The cancer stem cell hypothesis suggests that tumors are initiated and maintained by cancer stem cells capable of self-renewal and differentiation into mature tumor cells. Recent studies have demonstrated the existence of cancer initiating cells in different solid tumors. In this study, we identified a subpopulation of CD44+ cells within the tumor of gastric cancer patients, which, upon treatment by chemotherapeutic agent 5-fluorouracil (5-FU), were markedly enriched. In vitro culture of isolated CD44+ subpopulation from gastric tumors by magnetic beads sorting led to formation of gastric spheroid colonies. These colonies retained CD44+ surface marker expression during culture, and were undifferentiated in nature. Subcutaneous injections of CD44+ gastric cancer cells conferred tumorigenicity in SCID mice. Moreover, implantation of CD44+ cells from these established tumors remained tumorigenic in successive passages. Using CD44+ cells isolated from the gastric cell lines AGS and SGC7901, similar results were obtained. Upon enrichment by 5-FU, CD44+ cells harbored increased ALDH expression as compared with CD44- cells. Our results demonstrated for the first time the existence of CD44+ cells within the tumors of gastric cancer patients that are endowed with stem cells properties, and also provide a plausible explanation for chemo-resistance frequently observed in gastric cancer patients. Such findings provide a basis for further studies on targeting this tumorigenic subpopulation for better treatment of gastric cancer patients.

PIN1 inhibits apoptosis in hepatocellular carcinoma through modulation of the antiapoptotic function of survivin

PIN1, a peptidyl-prolyl-isomerase, binds a specific motif comprising a phosphorylated serine or threonine preceding a proline (p-Ser/Thr-Pro) residue in proteins. Through cis-trans isomerization, it induces conformational changes and modulates functions of many proteins that are involved in cell cycle progression, cell proliferation, and oncogenesis. PIN1 is overexpressed in hepatocellular carcinomas (HCC) and contributes to hepatocarcinogenesis. We investigated the role of PIN1 and the significance of its interaction with the inhibitor of apoptosis protein survivin in evading apoptosis in HCC cells. Using cell line and xenograft models, we determined that PIN1 overexpression inhibits apoptosis through suppression of caspase-3 and caspase-9 activity. In addition, down-regulation of survivin in PIN1-overexpressing cells attenuated the antiapoptotic effect induced by PIN1, suggesting that the inhibition of apoptosis is mediated through PIN1-survivin interaction. Coimmunoprecipitation assays showed that PIN1 interacted with survivin via the phosphorylated Thr34-Pro35 motif and enhanced binding among survivin phosphorylated at Thr34, hepatitis B X-interacting protein (HBXIP), and pro-caspase-9. Taken together, these results suggest that the inhibition of apoptosis by PIN1 in HCC cells is mediated through modulation of the antiapoptotic function of survivin by increasing its binding to pro-caspase-9 via HBXIP. Such functional interaction between PIN1 and survivin may therefore play an important role in hepatocarcinogenesis and chemoresistance.

Circulating microRNAs as specific biomarkers for breast cancer detection

BACKGROUND

We previously showed microRNAs (miRNAs) in plasma are potential biomarkers for colorectal cancer detection. Here, we aimed to develop specific blood-based miRNA assay for breast cancer detection.

METHODOLOGY/PRINCIPAL FINDINGS

TaqMan-based miRNA profiling was performed in tumor, adjacent non-tumor, corresponding plasma from breast cancer patients, and plasma from matched healthy controls. All putative markers identified were verified in a training set of breast cancer patients. Selected markers were validated in a case-control cohort of 170 breast cancer patients, 100 controls, and 95 other types of cancers and then blindly validated in an independent set of 70 breast cancer patients and 50 healthy controls. Profiling results showed 8 miRNAs were concordantly up-regulated and 1 miRNA was concordantly down-regulated in both plasma and tumor tissue of breast cancer patients. Of the 8 up-regulated miRNAs, only 3 were significantly elevated (p<0.0001) before surgery and reduced after surgery in the training set. Results from the validation cohort showed that a combination of miR-145 and miR-451 was the best biomarker (p<0.0001) in discriminating breast cancer from healthy controls and all other types of cancers. In the blind validation, these plasma markers yielded Receiver Operating Characteristic (ROC) curve area of 0.931. The positive predictive value was 88% and the negative predictive value was 92%. Altered levels of these miRNAs in plasma have been detected not only in advanced stages but also early stages of tumors. The positive predictive value for ductal carcinoma in situ (DCIS) cases was 96%.

CONCLUSIONS

These results suggested that these circulating miRNAs could be a potential specific biomarker for breast cancer screening.

Treatment of functional dyspepsia with sertraline: A double-blind randomized placebo-controlled pilot study

AIM: To evaluate sertraline, a selective serotonin reuptake inhibitor in the treatment of patients with functional dyspepsia.

METHODS: Consecutive tertiary hospital patients with a clinical diagnosis of functional dyspepsia (FD) according to the Rome II criteria with a Hong Kong dyspepsia index (HKDI) of greater than 16 were recruited. Patients commenced enrolment prior to the inception of the Rome III criteria for functional dyspepsia. All patients were ethnic Chinese, had a normal upper endoscopy and were Helicobacter pylori negative prior to enrolment. Study patients were randomized to receive sertraline 50 mg or placebo daily for 8 wk. HKDI symptom scores, quality of life, hospital anxiety and depression (HAD) scale and global symptom relief were evaluated before, during and after treatment. Adverse effects were monitored during and after treatment.

RESULTS: A total of 193 patients were randomized in the intention to treat (ITT), and 150 patients were included in the per protocol (PP) analysis. In both the ITT and PP, there was no difference in the primary outcome of global dyspepsia symptoms between the sertraline and placebo groups at week 8. In the ITT analysis, 98 and 95 patients were randomized to the sertraline and placebo groups respectively. A total of 43 patients withdrew from the study (22.3%) by week 8, with 23 of the 24 drop-outs in the sertraline group occurring prior to week 4 (95.8%). In contrast, in the placebo arm, 11 of 19 patients dropped out by week 4 (57.9%). Utilizing the last response carried forward to account for the drop-outs, there were no differences between the sertraline and placebo groups at baseline in terms of the HKDI, HKDI 26.08 ± 6.19 vs 26.70 ± 5.89, P = 0.433; and at week 8, HKDI 22.41 ± 6.36 vs 23.25 ± 7.30, P = 0.352 respectively. In the PP analysis, 74 and 76 patients were randomized to the sertraline and placebo groups respectively. At baseline, there were no statistically significant differences between the sertraline and placebo groups, HKDI 25.83 ± 6.313 vs 27.19 ± 5.929 respectively, P = 0.233; however by week 8, patients in the sertraline group demonstrated a statistically significant difference in their Hong Kong Dyspepsia Index compared to placebo, HKDI 20.53 ± 6.917 vs 23.34 ± 7.199, P = 0.02, respectively). There was also no statistically significant difference in overall quality of life measures or the HAD scale related to treatment in either the ITT or PP analysis at week 8.

CONCLUSION: This pilot study, the first to examine sertraline, a selective serotonin reuptake inhibitor, for the management of FD, did not find that it was superior to placebo.

Decreased peripheral blood mitochondrial DNA content is related to HbA1c, fasting plasma glucose level and age of onset in type 2 diabetes mellitus

AIMS

Mitochondrial DNA (mtDNA) content is essential for maintaining normal mitochondrial function, and the mitochondrial function is critical for the production and the release of insulin in Type 2 diabetes mellitus. We investigated whether peripheral blood mtDNA content was reduced in Type 2 diabetes, and what were the major factors?

METHODS

The mtDNA content of peripheral blood in a sample of 147 Type 2 diabetes and 170 normal Chinese subjects was determined by amplification of the mitochondrial gene CYT-B and normalized by a nuclear DNA β-globin gene. Fasting plasma glucose, HbA(1c) , fasting plasma insulin and lipid profile (HDL-cholesterol, LDL-cholesterol, total cholesterol, triglyceride) were analysed with commercial kits on an automatic analyser.

RESULTS

In Type 2 diabetes group, the mean HbA(1c) was 62 mmol/mol (7.8%). Moreover, BMI, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, LDL-cholesterol, triglyceride, fasting plasma insulin and homeostasis model assessment for insulin resistance were significantly higher in Type 2 diabetes group than that in control group. Peripheral blood mtDNA content was 24% lower than that in the controls (1.4 ± 0.5 vs. 1.8 ± 0.7, P < 0.001). The mtDNA content was negatively correlated with BMI, fasting plasma glucose, fasting plasma insulin, homeostasis model assessment for insulin resistance (P < 0.01), and age, triglyceride and LDL-cholesterol levels (P < 0.05); while positively correlated with HDL-cholesterol level (P < 0.05) in both groups. Stepwise regression analysis indicated that HbA(1c), fasting plasma glucose and age of onset were the major factors affecting the mtDNA content in the Type 2 diabetes group; however, BMI was the only variable associated with lower mtDNA content in control group.

CONCLUSION

Our results demonstrate that lower peripheral blood mtDNA content is associated with Type 2 diabetes in Chinese individuals, and HbA(1c), fasting plasma glucose and age of onset are the major factors affecting the mtDNA content.

The use of single-agent sorafenib in the treatment of advanced hepatocellular carcinoma patients with underlying Child-Pugh B liver cirrhosis: a retrospective analysis of efficacy, safety, and survival benefits

BACKGROUND

This study explored the efficacy, tolerability, and survival benefits of using sorafenib in patients with Child-Pugh class B (CPB) cirrhosis.

METHODS

Patients with advanced hepatocellular carcinoma who were treated with sorafenib at Queen Mary Hospital, Hong Kong, China, were analyzed retrospectively. Treatment outcomes were analyzed according to their respective Child-Pugh status. Patients with CPB disease were further divided into CPB7 (those with a score of 7) and CPB8-9 (a score of 8 or 9) subgroups.

RESULTS

The baseline demographic parameters were comparable between 108 patients with Child-Pugh class A (CPA) disease and 64 CPB patients. Both clinical benefit rate (21.3% vs 32.4% vs 14.8%; P = .23) and progression-free survival (median: 3.2 months vs 3.2 months vs 2.3 months; P = .26) were similar among CPA, CPB7, and CPB8-9 groups, respectively. The overall survival was different among these groups (P = .002) and showed a trend toward worse outcome in CPB patients: the median was 6.1, 5.4, and 2.7 months among CPA, CPB7, and CPB8-9 patients, respectively. The commonest grade 3/4 adverse events were hand-foot syndrome (13.5%), diarrhea (9.9%), and rash (7.0%). Grade 3/4 leukopenia, thrombocytopenia, and anemia occurred in 2.9%, 5.3%, and 8.8% of the patients, respectively. Overall, the 3 groups of patients experienced similar incidence of most of these adverse events. Nonetheless, CPB patients experienced more anemia (P = .01), gastrointestinal bleeding (P = .02), and hepatic encephalopathy (P = .02).

CONCLUSIONS

CPA and CPB patients tolerated sorafenib similarly and derived similar clinical and progression-free survival benefit. Among CPB patients, most benefits were observed in patients with a score of 7. Nevertheless, CPB patients were more susceptible to developing cirrhotic complications, and thus more vigilant surveillance is needed.

Phase II study of bevacizumab and erlotinib in the treatment of advanced hepatocellular carcinoma patients with sorafenib-refractory disease

Background The combination of bevacizumab (B) and erlotinib (E) has shown promising clinical outcomes as the first-line treatment of advanced HCC patients. We aimed to evaluate the efficacy and safety of using combination of B + E in treating advanced HCC patients who had failed prior sorafenib treatment. Methods Eligible advanced HCC patients with documented radiological evidence of disease progression with sorafenib treatment were recruited. All patients received bevacizumab(B) at 10 mg/kg every 2 weeks with erlotinib(E) at 150 mg daily for a maximum of 6 cycles. Response assessments using both RECIST and modified RECIST criteria were performed after every 6 weeks. The primary endpoint was clinical benefit (CB) rate and a Simon two-stage design was employed. Results The trial was halted in the first stage according to the pre-set statistical criteria with 10 patients recruited. The median age was 47 years (range, 28–61) and all patients were in ECOG performance status 1. Eighty percent of patients were chronic hepatitis B carriers and all patients had Child A cirrhosis. Among these 10 patients, none of the enrolled patients achieved response or stable disease. The median time-to-progression was 1.81 months (95 % confidence interval [C.I.], 1.08–1.74 months) and overall survival was 4.37 months (95 % C.I., 1.08–11.66 months). Rash (70 %), diarrhea (50 %) and malaise (40 %) were the most commonly encountered toxicities. Conclusion The combination of B + E was well tolerated but had no activity in an unselected sorafenib-refractory advanced HCC population. Condensed abstract The combination of bevacizumab and erlotinib had no clinical activity in sorafenib-refractory HCC population.

The significance of early alpha-fetoprotein level changes in predicting clinical and survival benefits in advanced hepatocellular carcinoma patients receiving sorafenib

BACKGROUND

he role of serum alpha-fetoprotein (AFP) changes in predicting the treatment outcomes of advanced hepatocellular carcinoma (HCC) patients to sorafenib remains unknown.

METHODS

Serum AFP was collected prospectively at baseline and subsequent follow-up visits in parallel with clinical and survival outcomes. AFP response was defined as a relative drop of AFP >20% of the baseline level after 6 weeks of sorafenib. The relationship between AFP response and the treatment outcomes was first explored in patients who received sorafenib in a phase II study. Subsequently, an independent validation set of patients were obtained to validate the association of AFP response to clinical outcomes.

RESULTS

Included in the exploration and validation sets for analysis were 41 and 53 patients, respectively, with baseline AFP level >20 μg/L. In the exploration cohort, AFP response was significantly associated with clinical benefit (CB) rate (relative chance 3.4, 95% confidence interval [CI], 1.1-11.1), and multivariate analysis indicated that AFP response was associated with significantly better progression-free survival (PFS) (hazard ratio [HR], 0.31; 95% CI, 0.13-0.76) and marginally better overall survival (OS) (HR, 0.30; 95% CI, 0.09-1.02). When applying AFP changes in the validation set, significant associations were again found between AFP response with CB rate (relative chance, 5.5; 95% CI, 2.3-13.6) and PFS (HR, 0.12; 95% CI, 0.04-0.30) but not OS (HR, 0.61; 95% CI, 0.27-1.26).

CONCLUSION

Drop in AFP level at 6 weeks is an exploratory early surrogate for both CB and PFS in advanced HCC patients receiving sorafenib.

Treatment of non-erosive reflux disease with a proton pump inhibitor in Chinese patients: a randomized controlled trial

BACKGROUND

Evidence suggests that rates of gastroesophageal reflux disease are increasing in the Asia-Pacific region, where patients tend to have predominantly non-erosive reflux disease as opposed to erosive (reflux) esophagitis. At present, data for the responsiveness of non-erosive reflux disease to proton pump inhibition are scant. We aimed to study esomeprazole for the treatment of non-erosive reflux disease in Chinese patients.

METHODS

Patients with a clinical diagnosis of gastroesophageal reflux, and a locally validated reflux index, the Chinese GerdQ, of equal to or greater than 12 were recruited and randomized to receive esomeprazole 20 mg daily or placebo for 8 weeks. Reflux index scores, quality of life (SF-36), and the hospital anxiety and depression (HAD) scale and symptom relief were evaluated before, during, and after treatment.

RESULTS

A total of 175 patients were randomized. Patients in the esomeprazole group (n = 85) demonstrated statistically significant reductions in their GerdQ index, from 19.45 to 15.37 and to 14.32 (p = 0.013, p = 0.005) at weeks 4 and 8, respectively. Compared to placebo at week 8, 57.1% of patients on esomeprazole found that their symptoms had resolved or were acceptable compared with 37.2% in the placebo group (p = 0.001). There were no statistically significant differences in overall quality-of-life measures or the HAD scale related to treatment.

CONCLUSIONS

This study suggests that esomeprazole is efficacious in treating Chinese patients with non-erosive reflux disease.

Abstract 2365: Actopaxin: A novel regulator of cell migration and invasion in human hepatocellular carcinoma

Background: The mortality rate of hepatocellular carcinoma (HCC) is high due to tumor recurrence and development of metastasis, involving cell spreading, lamellipodia formation and cell migration. Formation of focal adhesions is a key regulator of cell motility and cell invasion. Actopaxin, a focal adhesion and cytoskeleton-associated protein, is required for such processes. The aim of this study was to examine the role of Actopaxin in HCC cell migration, invasion and development of metastasis.

Methods: The expression of Actopaxin in primary and metastatic liver cancer cell-lines was examined by western blot and RT-PCR. The functional and molecular effects of Actopaxin expression were studied by transient as well as stable enforced expression or down-regulation in HCC cell-lines. Immunofluorescence staining for actin cytoskeleton and focal adhesion was performed to examine the effect of Actopaxin expression on cell shape, stress fiber organization, and focal adhesion. The clinicopathological significance of Actopaxin expression in tumorous tissues of 119 HCC patients was also investigated.

Results: High protein level of Actopaxin was found in the metastatic HCC cell-lines compared with other non-metastatic HCC cell-lines. Expression of a shorter form of Actopaxin was also detected in some of these cell-lines. Comparing to Actopaxin (LF-Actopaxin), the unreported short form (SF-Actopaxin) lacks a fragment in the C-terminal and hence results in an incomplete 2nd CH domain which consists binding sites for its downstream activation targets. Expression of LF-Actopaxin but not SF-Actopaxin in HCC cell-lines was positively correlated with their migration and invasion potential in vitro, accompanied by altered expressions of several focal adhesion proteins as well as EMT proteins. Study in clinical samples showed that LF-Actopaxin expression was positively correlated with tumor size (p&lt;0.05) while SF-Actopaxin expression was lower in HCC tumor compared with corresponding nontumorous liver (p&lt;0.001) and lower in HCC with metastasis compared with HCC without metastasis (p&lt;0.05).

Conclusion: This study demonstrated for the first time the pro-migratory effects of Actopaxin in human HCC, and the existence of SF-Actopaxin which displays different expression pattern as well as functional and molecular effects.

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Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2365. doi:10.1158/1538-7445.AM2011-2365

Abstract 2554: Synergistic antitumor effect of AUY922 in combination with sorafenib in hepatocellular carcinoma cells

PURPOSE: Molecularly targeted therapy is of particular importance for HCC due to a lack of efficacy with currently approved chemo-toxic therapies. It is of interest to investigate the combined effect of two molecular targeted drugs, sorafenib (a multi-kinase inhibitor with anti-angiogenic, pro-apoptotic and Raf kinase inhibitory activity) and a highly potent non-geldamycin HSP90 inhibitor, NVP-AUY922 on HCC treatment. EXPERIMENTAL DESIGNS: Cell viability after different treatments was measured by both 3,[4,5-dimethylthiazol-2-yl] -2,5-diphenyl-tetrazolium bromide (MTT) assay and cytofluorometric annexin-V apoptotic assay to compare the apoptotic cells induced by single versus combined treatment. Cell cycle analysis was also performed, and Western blotting was employed to determine the effects on MEK signaling, and in vivo efficacy was determined in nude mice with PLC/PRF/5 xenografts. RESULTS: Combined drugs treatment produced a synergistic effect on decreased HCC cell viability shown by MTT assay. An increase in the number of apoptotic cells were observed by apoptotic assay in combined drugs group when compared with single agents sorafenib or NVP-AUY922. Also, sorafenib combined with NVP-AUY922 induced S-phase arrest which was demonstrated by cell cycle analysis. Sorafenib alone decreases phospho-Erk1/2 expression, and this effect was further enhanced in combination treatment with NVP-AUY922. Finally, sorafenib plus NVP-AUY922 significantly suppressed PLC/PRF/5 xenograft tumor growth when compared with single (NVP-AUY922 or Sorafenib) treatment alone. CONCLUSION: The combination therapy of sorafenib and NVP-AUY922 can be a new and promising therapeutic approach to the treatment of HCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2554. doi:10.1158/1538-7445.AM2011-2554

Phase 1-2 trial of PTK787/ZK222584 combined with intravenous doxorubicin for treatment of patients with advanced hepatocellular carcinoma: implication for antiangiogenic approach to hepatocellular carcinoma

BACKGROUND

This phase 1-2 trial assessed the efficacy and tolerability of an oral angiogenesis inhibitor-PTK787/ZK222584 (PTK)-in combination with intravenous doxorubicin for the treatment of advanced hepatocellular carcinoma (HCC) patients.

METHODS

In phase 1, advanced HCC patients received PTK at escalating doses together with doxorubicin 60 mg/m2 given as an intravenous bolus every 3 weeks to establish the maximum tolerated dose (MTD). Subsequently, in phase 2, all patients received the same regimen with oral PTK at the MTD dose every 3 weeks for a maximum of 6 cycles.

RESULTS

Nine patients were recruited in phase 1, with the MTD established as 750 mg daily. Overall, 27 patients received the regimen with PTK at 750 mg daily. The median age was 52 years (range, 23-73 years), and 63 percent of patients were chronic hepatitis B carriers. Notably, the majority of patients had Child-Pugh B cirrhosis. The overall response rate was 26.0%, with all the responding patients having partial response. Another 20% of patients achieved stable disease for at least 12 weeks. The median progression-free survival was 5.4 months (range, 0.27-23.6 months), and overall survival was 7.3 months (range, 0.8-23.6 months). The commonest grade 3 or 4 nonhematological toxicities were mucositis (11%) and alopecia (7%), respectively. Grade 3 or 4 neutropenia was observed in 7 (26%) patients; 2 had neutropenic sepsis.

CONCLUSIONS

The combination of PTK with intravenous doxorubicin shows encouraging activity in treating advanced HCC patients.

A subpopulation of CD26+ cancer stem cells with metastatic capacity in human colorectal cancer

Recent evidence suggests that a subpopulation of cancer cells, cancer stem cells (CSCs), is responsible for tumor growth in colorectal cancer. However, the role of CSCs in colorectal cancer metastasis is unclear. Here, we identified a subpopulation of CD26(+) cells uniformly present in both the primary and metastatic tumors in colorectal cancer patients with liver metastasis. Furthermore, in patients without distant metastasis at the time of presentation, the presence of CD26(+) cells in their primary tumors predicted distant metastasis on follow-up. Isolated CD26(+) cells, but not CD26(-) cells, led to development of distant metastasis when injected into the mouse cecal wall. CD26(+) cells were also associated with enhanced invasiveness and chemoresistance. Our findings have uncovered a critical role of CSCs in metastatic progression of cancer. Furthermore, the ability to predict metastasis based on analysis of CSC subsets in the primary tumor may have important clinical implication as a selection criterion for adjuvant therapy.

Promoter hypermethylation and histone hypoacetylation contribute to pancreatic-duodenal homeobox 1 silencing in gastric cancer

BACKGROUND AND AIMS

The expression of pancreatic-duodenal homeobox 1 (PDX1) in gastric cancer is aberrantly reduced. The aim of this study was to elucidate the regulation of DNA methylation and histone acetylation at the promoter for PDX1 silencing in gastric cancer.

METHODS

PDX1 expression in response to demethylation and acetylation was detected in human gastric cancer cell lines by reverse transcription-polymerase chain reaction (PCR) and western blot. Four CpG islands within the 5'-flanking region of PDX1 gene were analyzed with their transcription activities being detected by dual luciferase assay. Promoter hypermethylation was identified in gastric cancer cell lines and cancer tissues by methylation-specific PCR or bisulfite DNA sequencing PCR analysis. Histone acetylation was determined by chromatin immunoprecipitation (ChIP) assay.

RESULTS

Demethylation by 5'-aza-2'-deoxycytidine (5'-aza-dC) and/or acetylation by trichostatin A (TSA) restored PDX1 expression in gastric cancer cells. Hypermethylation was found in four CpG islands in six of seven cancer cell lines. However, only the distal CpG island located in the promoter fragment of PDX1, F383 (c.-2063 to -1681 nt upstream of the ATG start codon) displayed significant transcriptional activity that could be suppressed by SssI methylase and increased by 5'-aza-dC and TSA. More than 70% of the single CpG sites in F383 were methylated with hypermethylation of F383 fragment more common in gastric cancerous tissues compared with the paired normal tissues (P < 0.05). ChIP assay showed F383 was also associated with low hypoacetylation level of the histones.

CONCLUSION

Promoter hypermethylation and histone hypoacetylation contribute to PDX1 silencing in gastric cancer.

Trend of colorectal cancer in Hong Kong: 1983-2006

BACKGROUND AND AIM

The incidence of colorectal cancer (CC) is increasing in many Asian countries, but decreasing in western countries. The present study examined the local incidence of CC in the past few decades.

METHODS

A population based study, using data from Hong Kong (HK) Cancer Registry, was carried out to examine the trends of CC in different age groups in HK. Comparison with other countries was made.

RESULTS

The crude rate of CC in HK increased from 29.6/100,000 in 1983 to 57.1/100,000 in 2006. Age standardized rate (ASR) increased by less than 20%. It was markedly smaller than the 190% increase in crude rate. ASR progressively increased in males. In females, ASR peaked in 1994 and declined in the last decade. In most countries, the risk of CC was higher and increasing in males, but stable or decreasing in females. With respect to age, increasing risk was noted in males above 60 years old and females above 70 years old. However, a declining rate was noted in those below 50 years old. The decrease was over 40% in the 30-34 years group over the past two decades.

CONCLUSIONS

Increasing incidence of CC in HK was mostly in the older and male population, but not in the younger age group.

Abstract 3027: Plasma microRNA as a potential marker for breast cancer detection

Background: Recently, the emergence of small non-protein-coding RNAs, so-called microRNAs (miRNAs), playing important roles in oncogenesis has opened new opportunities for early cancer diagnosis. We have previously shown that microRNAs (miRNAs) in plasma are promising biomarkers for colorectal cancer detection. Here, we investigated whether plasma miRNAs could discriminate patients with and without breast cancer (BC).

Methods: Using TaqMan-based low density miRNA array, miRNAs were profiled from cancerous and adjacent non-cancerous breast tissues, corresponding plasma of 5 BC patients, along with plasma from 5 healthy controls. Marker selection and validation were performed by real-time quantitative RT-PCR on a small set of plasma. Independent set of plasma from 80 BC patients, 20 gastric cancer, 20 lung cancer, 20 colorectal cancer, 20 hepatocellular carcinoma and 50 healthy controls were further validated.

Results: Of the panel of 377 miRNAs analyzed, 8 miRNAs (miR-16, miR-21, miR-27a, miR-141, miR-191, miR-200c, miR-210, miR-451) were up-regulated both in plasma and tissue samples of 5 BC patients. All 8 putative miRNA markers were validated on the plasma of 15 BC patients and 15 healthy controls. Only three miRNAs were significantly elevated in this cohort of BC patients (p&lt;0.0005). The plasma levels of the three markers in those 15 BC patients were significantly reduced after surgery (p&lt;0.05). Further validation with an independent set of plasma samples (n=210) indicated that two markers differentiate BC from normal subjects, colorectal cancer, gastric cancer, hepatocellular carcinoma and lung cancer. These two markers yielded a combined receiver operating characteristic curve area of 88.5%, the sensitivity was 92% and the specificity was 72% in discriminating BC from control subjects.

Conclusions: Plasma miRNAs significantly elevated in BC patients are identified. This can be a novel noninvasive molecular marker for BC screening.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3027.

Abstract 1212: PIN1 enhances the anti-apoptotic function of survivin in cancer cells

Introduction: The peptidyl prolyl cis/trans isomerase 1 (PIN1) binds the specific motif comprising a phosphorylated serine or threonine residue preceding a proline (pSer/Thr-Pro) in proteins. PIN1 catalyses isomerisation of the prolyl peptide bond, and subsequently induces conformational changes in the substrates and modulates their functions. Through this mechanism, PIN1 is involved in many cellular events, including cell cycle progression, cell proliferation and cell transformation. Our previous work has revealed that PIN1 is over-expressed in hepatocellular carcinomas (HCC) and enhances hepatocarinogenesis. In this study, we investigated the role of the interaction between PIN1 and Survivin, an inhibitor of apoptosis protein (IAP), in tumorigenesis.

Methods and Results: By co-immunoprecipitation experiments, we found that PIN1 interacted with Survivin via the phosphorylated Thr34-pro motif in Survivin. We then further investigated the effects of PIN1 on the anti-apoptotic function of Survivin using flow cytometry by staining the cells with Annexin V and 7-AAD. Both caspase-9 and caspase-3 activities were also detected by flow cytometry. Through these experiments, over-expression of PIN1 in cervical carcinoma HeLa and human nontumorigenic liver MIHA cells were found to suppress the apoptotic response induced by staurosporine through inactivation of caspase-9 and caspase-3. However, the expression of the PIN1 mutants that are catalytically inactive or defective for protein-binding activity did not result in an inhibition of apoptosis. Likewise, the targeted inhibition of PIN1 by small interfering RNA in HeLa and human hepatoma PLC/PRF/5 cells enhanced the apoptotic response induced by staurosporine through caspase-9 and caspase-3 activation. In addition, down-regulation of Survivin by small interfering RNA in PIN1 over-expressing cells abolished the anti-apoptotic effect induced by PIN1, suggesting that the inhibition of apoptosis is mediated through the PIN1-Survivin interaction.

Conclusion: Since phosphorylation of Thr34 in Survivin suppresses pro-caspase-9 activation by increasing the binding between Survivin and pro-caspase-9, our results suggest that PIN1 may further regulate the anti-apoptotic role of Survivin through modulation of its binding to pro-caspase-9.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1212.

Embryonic-like stem cell derived from adult bone marrow: immature morphology, cell surface markers, ultramicrostructure and differentiation into multinucleated fibers in vitro

Embryonic-like stem cell (ELSC), expressing part of surface markers of human embryonic stem cells, may be a better candidate for cell therapy of degenerative muscular disease than mesenchymal stem cell (MSC). We isolated ELSC and MSC from bone marrow, respectively, and compared their differences in the characteristics and the capacity of myogenic differentiation. Results showed that ELSC could be isolated successfully from 3 adult bone marrow samples by using serum-free medium with 10ng/ml basic fibroblast growth factor (bFGF). At the same cell density, MSC could also be isolated from the same samples by using DMEM/F12 medium containing 10% new cattle serum. However, ELSC appeared as small, morphologically slenderer, upregulated expression of SSEA-4 and ultramicroscopically more immature than MSC derived from the same samples. Immunofluorescent staining and RT-PCR analysis showed ELSC weakly expressed Oct-4, Nanog-3 and Sox-2. Moreover, ELSC and MSC could be induced into long, multinucleated fibers expressing myogenin and myosin heavy chain (MHC) in myogenic differentiation medium, but by day 10, proportion of multinucleated fibers positive for MHC was respectively 25.0%+/-6.9% and 13.8%+/-7.6% in ELSC and MSC culture. These data suggest that bone marrow derived ELSC represent an ideal candidate for cell therapy of degenerative muscular disease.