Khee Chee Soo

Nanoparticles in Photodynamic Therapy

Sasidharan Swarnalatha Lucky,†,§ Khee Chee Soo,‡ and Yong Zhang*,†,§,∥ †NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, Singapore, Singapore 117456 ‡Division of Medical Sciences, National Cancer Centre Singapore, Singapore, Singapore 169610 Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore 117576 College of Chemistry and Life Sciences, Zhejiang Normal University, Zhejiang, P. R. China 321004

Over-expression of the mitogen-activated protein kinase (MAPK) kinase (MEK)-MAPK in hepatocellular carcinoma: Its role in tumor progression and apoptosis

BackgroundHepatocellular carcinoma (HCC) is one of the most common malignancies in South East Asia. Although activation of the MEK-MAPK is often associated with cellular growth, the role of MEK-MAPK in growth and survival of hepatocarcinoma cells has not been established.MethodsImmuno-histochemistry was used to localize phosphorylated MAPK and MEK1/2 in the tissues. 3-(4,5-Dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide (MTT) assay and ELISA were used to determine cell viability and cell proliferation. Deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was used to detect apoptotic cells. Western blots analysis was performed to determine the levels of proteins involved in the MEK-MAPK and apoptotic pathways. Transfection study was performed to assess the role of MEK-MAPK pathway in growth and survival of liver cancer cells.ResultsWe report that phosphorylation of MEK1/2 at Ser217/221 was detected by immuno-histochemistry in 100% (46 of 46) of HCCs examined. A positive signal was localized in the nuclei of hepatocarcinoma cells but not in dysplastic hepatocytes or stromal cells. Over-expression and phosphorylation of MAPK was also detected in 91% (42 of 46) and 69% (32 of 46) of HCCs examined, respectively. The percentage of cells showing positively for phosphorylated MEK1/2 increased with advancing tumor stage. In vitro, treatment of human HepG2 and Hep3B cells with MEK1/2 specific inhibitors U0126 and PD98059 led to growth inhibition and apoptosis. U0126 induced the release of cytochrome c and increased the cleavage of caspase-3, caspase-7, and poly ADP-ribose polymerase (PARP). Inhibition of phosphatidylinositol 3-kinase (PI-3K), c-Jun N-terminal kinase (JNK) and p38 kinase activities caused only a mild apoptosis in HepG2 and Hep3B cells. Activated MEK1-transfected cells were more resistant to UO126-induced apoptosis in vitro and formed larger tumors in SCID mice than mock-transfected cells.ConclusionIn conclusion, our results demonstrate that MEK-MAPK plays an important role in the growth and survival of liver cancer cells and suggest that blocking MEK-MAPK activity may represent an alternative approach for the treatment of liver cancer.

Brivanib Alaninate, a Dual Inhibitor of Vascular Endothelial Growth Factor Receptor and Fibroblast Growth Factor Receptor Tyrosine Kinases, Induces Growth Inhibition in Mouse Models of Human Hepatocellular Carcinoma

Purpose: Hepatocellular carcinoma (HCC) is the fifth most common primary neoplasm; surgery is the only curative option but 5-year survival rates are only 25% to 50%. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) are known to be involved in growth and neovascularization of HCC. Therefore, agents that target these pathways may be effective in the treatment of HCC. The aim of this study was to determine the antineoplastic activity of brivanib alaninate, a dual inhibitor of VEGF receptor (VEGFR) and FGF receptor (FGFR) signaling pathways. Experimental Design: Six different s.c. patient-derived HCC xenografts were implanted into mice. Tumor growth was evaluated in mice treated with brivanib compared with control. The effects of brivanib on apoptosis and cell proliferation were evaluated by immunohistochemistry. The SK-HEP1 and HepG2 cells were used to investigate the effects of brivanib on the VEGFR-2 and FGFR-1 signaling pathways in vitro. Western blotting was used to determine changes in proteins in these xenografts and cell lines. Results: Brivanib significantly suppressed tumor growth in five of six xenograft lines. Furthermore, brivanib–induced growth inhibition was associated with a decrease in phosphorylated VEGFR-2 at Tyr1054/1059, increased apoptosis, reduced microvessel density, inhibition of cell proliferation, and down-regulation of cell cycle regulators. The levels of FGFR-1 and FGFR-2 expression in these xenograft lines were positively correlated with its sensitivity to brivanib-induced growth inhibition. In VEGF-stimulated and basic FGF stimulated SK-HEP1 cells, brivanib significantly inhibited VEGFR-2, FGFR-1, extracellular signal-regulated kinase 1/2, and Akt phosphorylation. Conclusion: This study provides a strong rationale for clinical investigation of brivanib in patients with HCC.

Oncogenic pathway combinations predict clinical prognosis in gastric cancer.

Many solid cancers are known to exhibit a high degree of heterogeneity in their deregulation of different oncogenic pathways. We sought to identify major oncogenic pathways in gastric cancer (GC) with significant relationships to patient survival. Using gene expression signatures, we devised an in silico strategy to map patterns of oncogenic pathway activation in 301 primary gastric cancers, the second highest cause of global cancer mortality. We identified three oncogenic pathways (proliferation/stem cell, NF-kappaB, and Wnt/beta-catenin) deregulated in the majority (>70%) of gastric cancers. We functionally validated these pathway predictions in a panel of gastric cancer cell lines. Patient stratification by oncogenic pathway combinations showed reproducible and significant survival differences in multiple cohorts, suggesting that pathway interactions may play an important role in influencing disease behavior. Individual GCs can be successfully taxonomized by oncogenic pathway activity into biologically and clinically relevant subgroups. Predicting pathway activity by expression signatures thus permits the study of multiple cancer-related pathways interacting simultaneously in primary cancers, at a scale not currently achievable by other platforms.

Critical Appraisal of 232 Consecutive Distal Pancreatectomies With Emphasis on Risk Factors, Outcome, and Management of the Postoperative Pancreatic Fistula : A 21-Year Experience at a Single Institution

OBJECTIVE To critically analyze a large single-institution experience with distal pancreatectomy (DP), with particular attention to the risk factors, outcome, and management of the postoperative pancreatic fistula (PF). DESIGN Retrospective study. SETTING Tertiary referral center. PATIENTS A total of 232 consecutive patients with pancreatic or extrapancreatic disease necessitating DP over 21 years. INTERVENTIONS Twenty-one patients underwent spleen-preserving DP, 117 underwent DP with splenectomy, and 94 underwent DP with multiorgan resection. MAIN OUTCOME MEASURES The perioperative and postoperative data of patients who underwent DP were analyzed. This included factors associated with postoperative morbidity with particular attention to the PF (defined by the International Study Group of Pancreatic Fistula) and changing trends in operative and perioperative data during the study period. RESULTS The overall operative morbidity and mortality were 47% (107 patients) and 3% (7 patients), respectively. During the study period, the rates of resection increased from 3 cases to 23 per year, and increasingly these were performed for smaller and incidental lesions. The morbidity rate remained unchanged, but there was a decline in postoperative stay and the need for care in the intensive care unit. Pancreatic fistulas occurred in 72 patients (31%); 41 (18%) were grade A, 13 (6%) grade B, and 18 (8%) grade C. Increased weight, higher American Society of Anesthesiologists score, blood loss greater than 1 L, increased operation time, decreased albumin level, and sutured closure of the stump without main duct ligation were associated with a postoperative PF on univariate analysis. A DP with splenectomy was associated with a higher incidence of grade B or C PF and non-PF-related complications. Ninety-two percent of PFs were successfully managed nonoperatively. Clinical outcomes correlated well with PF grading, as evidenced by the progressive increase in outcome measures such as postoperative stay, readmissions, reoperations, radiologic interventions, and non-PF-related complications from grade A to C PFs. CONCLUSIONS Pancreatic fistula is the most common complication after DP and its incidence varies depending on the definition applied. Several risk factors for developing a PF were identified. Splenic preservation after DP is safe. The grade of a PF correlates well with clinical outcomes, and most PFs may be managed nonoperatively.

Loss of Parafibromin Immunoreactivity Is a Distinguishing Feature of Parathyroid Carcinoma

Purpose: A reliable method for diagnosing parathyroid carcinoma has remained elusive over the years, resulting in its under-recognition and suboptimal therapy. Obtaining an accurate diagnosis has become an even more pressing matter with recent evidence that germline HRPT2 gene mutations are found in patients with apparently sporadic parathyroid carcinoma. There is a high prevalence of HRPT2 gene mutations and biallelic inactivation in parathyroid carcinoma. We hypothesize that loss of parafibromin, the protein product of the HRPT2 gene, would distinguish carcinoma from benign tissue. Experimental Design: We generated a novel antiparafibromin monoclonal antibody and performed immunostaining on 52 definite carcinoma specimens, 6 equivocal carcinoma specimens, 88 benign specimens, and 9 hyperparathyroidism-jaw tumor (HPT-JT) syndrome-related adenomas from patients with primary hyperparathyroidism from nine worldwide centers and one national database. Results: We report that the loss of parafibromin nuclear immunoreactivity has 96% sensitivity [95% confidence interval (CI), 85–99%] and 99% specificity (95% CI, 92–100%) in diagnosing definite carcinoma. Inter-observer agreement for evaluation of parafibromin loss was excellent, with unweighted kappa of 0.89 (95% CI, 0.79–0.98). Two equivocal carcinomas misclassified as adenomas were highlighted by parafibromin immunostaining. One of these tumors has since recurred, satisfying criteria for a definite carcinoma. Similarly, eight of nine HPT-JT syndrome-related adenomas showed absent nuclear immunoreactivity. Conclusions: Parafibromin is a promising molecular marker for diagnosing parathyroid carcinoma. The similar loss of parafibromin immunoreactivity in HPT-JT syndrome-related adenomas suggests that this is a pivotal step in parathyroid tumorigenesis.

Titania Coated Upconversion Nanoparticles for Near-Infrared Light Triggered Photodynamic Therapy

Because of the limited penetration depth of visible light that generally excites most of the available photosensitizers (PSs), conventional photodynamic therapy (PDT) is limited to the treatment of superficial and flat lesions. Recently, the application of deep penetrating near-infrared (NIR) light excitable upconversion nanoparticles (UCNs) in conjunction with PDT has shown to have clear potential in the treatment of solid tumors due to its ability to penetrate thick tissue. However, various constructs developed so far have certain limitations such as poor or unstable PS loading, reducing their therapeutic efficacy and limiting their application to solution or cell-based studies. In this work, we present a method to fabricate uniform core-shell structured nanoconstruct with a thin layer of photocatalyst or PS-titanium dioxide (TiO2) stably coated on individual UCN core. Our design allows controllable and highly reproducible PS loading, preventing any leakage of PS compared to previously developed nanoconstructs, thus ensuring repeatable PDT results. Further surface modification of the developed nanoconstructs with polyethylene glycol (PEG) rendered them biocompatible, demonstrating good therapeutic efficacy both in vitro and in vivo.

Targeted inhibition of the extracellular signal-regulated kinase kinase pathway with AZD6244 (ARRY-142886) in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy in Asia and Africa. We previously reported that overexpression of extracellular signal-regulated kinase (ERK) kinase 1/2 (MEK1/2) and ERK1/2 was detected in HCC, and that their activation was required for liver cancer cell proliferation and survival. In the present study, we determined the efficacy of a specific MEK1/2 inhibitor AZD6244 (ARRAY-142886) in treatment of HCC. Treatment of primary HCC cells with AZD6244 led to growth inhibition, elevation of the cleavage of caspase-3 and caspase-7, and cleaved poly(ADP)ribose polymerase, but inhibition of ERK1/2 and p90RSK phosphorylation. Studying the protein expression profile of seven HCC xenografts revealed that their growth rate was positively correlated with the levels of phosphorylated MEK. AZD6244, when given p.o. to mice bearing these xenografts, resulted in a dose-dependent inhibition of tumor growth. AZD6244-induced growth suppression was associated with inactivation of ERK1/2 and p90RSK, and up-regulation of activated caspase-3 and caspase-7, and cleaved poly(ADP)ribose polymerase. Our data suggest that the MEK-ERK pathway plays an important role in the growth and survival of liver cancer cells and that the HCC xenograft models are excellent tools for screening preclinical drugs. Targeted inhibition of the MEK-ERK pathway with AZD6244 may represent an alternative approach for the treatment of this disease. [Mol Cancer Ther 2007;6(1):138–45]

An Appraisal of Surgical and Percutaneous Drainage for Pyogenic Liver Abscesses Larger Than 5 cm

Objective:To determine whether first-line treatment with percutaneous or surgical drainage of liver abscesses larger than 5 cm results in better clinical outcome. Summary Background Data:Pyogenic liver abscesses larger than 5 cm are currently treated by intravenous antibiotics and either percutaneous (PD) or surgical drainage (SD). Percutaneous techniques have been increasingly performed in place of open drainage as first-line treatment. This paradigm shift has been fueled by the drive for low-risk and less-invasive procedures and the surgical option being reserved for percutaneous failures. Yet there is a lack of data to support percutaneous drainage over open surgical drainage as first-line treatment. Methods:Over a 3-year period, 80 patients with liver abscesses larger than 5 cm amenable to PD and SD were included in the study. This situation was possible as 1 team of surgeons favored the use of PD and 1 team favored the use of SD as first-line treatment. The treatment outcomes in both groups were compared, and clinical end-points included time to defervescence of fever, failure of treatment, secondary procedures, hospital stay, morbidity, and mortality. Results:PD was performed in 36 patients and SD in 44 patients as first-line treatment. Clinical, laboratory, and abscess parameters were comparable in both groups. Sixty-four of 80 patients (80%) had multiloculated abscess. The time to defervescence of fever was not statistically significant (PD versus SD, 4.85 versus 4.38 days; P = 0.09). However, SD had less treatment failures (3 versus 10, P = 0.013), less requirement for secondary procedures (5 versus 13, P = 0.01), and shorter length of hospital stay (8 versus 11 days, P = 0.03). There was no difference in morbidity or mortality rates. Conclusions:The results of our study show that for large liver abscesses more than 5 cm, SD provides better clinical outcomes than PD in terms of treatment success, number of secondary procedures, and hospital stay with comparable morbidity and mortality rates. SD should be considered as first-line treatment of large liver abscesses.

RAD001 (everolimus) inhibits tumour growth in xenograft models of human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide and highly resistant to available chemotherapies. Mammalian target of rapamycin (mTOR) functions to regulate protein translation, angiogenesis and cell cycle progression in many cancers including HCC. In the present study, subcutaneous patient‐derived HCC xenografts were used to study the effects of an mTOR inhibitor, RAD001 (everolimus), on tumour growth, apoptosis and angiogenesis. We report that oral administration of RAD001 to mice bearing patient‐derived HCC xenografts resulted in a dose‐dependent inhibition of tumour growth. RAD001‐induced growth suppression was associated with inactivation of downstream targets of mTOR, reduction in VEGF expression and microvessel density, inhibition of cell proliferation, up‐regulation of p27Kip1 and down‐regulation of p21Cip1/Waf1, Cdk‐6, Cdk‐2, Cdk‐4, cdc‐25C, cyclin B1 and c‐Myc. Our data indicate that the mTOR pathway plays an important role in angiogenesis, cell cycle progression and proliferation of liver cancer cells. Our study provides a strong rationale for clinical investigation of mTOR inhibitor RAD001 in patients with HCC.