Inhibition of tumour growth by Raf265 via blockade of Raf/MEK/ERK pathway in colorectal cancer

published_or_final_versionThe 15th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 16, abstract no. 1

Detection of CD44+ cancer initiating cells in pleural effusion of a liver cancer patient

published_or_final_versionThe 16th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 24, abstract no. 2

Anti-tumor efficacy of recombinant human arginase in combination with chemotherapeutic agents in human hepatocellular carcinoma

Poster Session 1: Translational & Clinical: no.41published_or_final_versionThe 16th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 23, abstract no. 2

Survivin depletion inhibits tumor growth and enhances chemosensitivity in hepatocellular carcinoma

Survivin is a member of the inhibitor of apoptosis family, which has been suggested to be crucial in the control of cell division and inhibition of apoptosis. Expression of this protein has been observed in transformed cell lines and human tumor tissues, including those from colorectal cancer, but not in terminally differentiated adult tissues. Survivin mRNA expression has frequently been detected in hepatocellular carcinoma (HCC) and its protein expression has been demonstrated to be highly correlated with proliferation index rather than apoptotic index. The present study aimed to analyze the effect of survivin on the tumorigenicity and chemosensitivity of HCC via the establishment of an HCC cell line (PLC/PRF/5) with the stable knockdown of the survivin gene (PLC-k3). This cell line displayed significantly lower rates of survival and proliferation in assays of cell viability and proliferation, respectively, compared with those of the control cell line (PLC-v). In addition, PLC-k3 cells were more sensitive to cisplatin treatment, resulting in S phase arrest. These findings were further confirmed by an in vivo experiment. The data of the present study suggest that survivin is critical in promoting cell proliferation but not in inhibition of apoptosis, and enhances the chemosensitivity of HCC. Thus, the suppression of survivin expression in combination with cisplatin may contribute to the development of more effective treatments for HCC.published_or_final_versio

Preclinical analysis of the anti-tumor and anti-metastatic effects of Raf265 on colon cancer cells and CD26(+) cancer stem cells in colorectal carcinoma

© 2015 Chow et al.Background: In colorectal carcinoma (CRC), activation of the Raf/MEK/ERK signaling pathway is commonly observed. In addition, the commonly used 5FU-based chemotherapy in patients with metastatic CRC was found to enrich a subpopulation of CD26+ cancer stem cells (CSCs). As activation of the Raf/MEK/ERK signaling pathway was also found in the CD26+ CSCs and therefore, we hypothesized that an ATP-competitive pan-Raf inhibitor, Raf265, is effective in eliminating the cancer cells and the CD26+ CSCs in CRC patients. Methods: HT29 and HCT116 cells were treated with various concentrations of Raf265 to study the anti-proliferative and apoptotic effects of Raf265. Anti-tumor effect was also demonstrated using a xenograft model. Cells were also treated with Raf265 in combination with 5FU to demonstrate the anti-migratory and invasive effects by targeting on the CD26+ CSCs and the anti-metastatic effect of the combined treatment was shown in an orthotopic CRC model. Results: Raf265 was found to be highly effective in inhibiting cell proliferation and tumor growth through the inhibition of the RAF/MEK/ERK signaling pathway. In addition, anti-migratory and invasive effect was found with Raf265 treatment in combination with 5FU by targeting on the CD26+ cells. Finally, the anti-tumor and anti-metastatic effect of Raf265 in combination with 5FU was also demonstrated. Conclusions: This preclinical study demonstrates the anti-tumor and anti-metastatic activity of Raf265 in CRC, providing the basis for exploiting its potential use and combination therapy with 5FU in the clinical treatment of CRC.published_or_final_versio

Prognostic significance of CD26 in patients with colorectal cancer

Background: CD26, dipeptidyl peptidase IV, was discovered firstly as a membrane-associated peptidase on the surface of leukocyte. We previously demonstrated that a subpopulation of CD26+ cells were associated with the development of distant metastasis, enhanced invasiveness and chemoresistance in colorectal cancer (CRC). In order to understand the clinical impact of CD26, the expression was investigated in CRC patient's specimens. This study investigated the prognostic significance of tumour CD26 expression in patients with CRC. Examination of CD26+ cells has significant clinical impact for the prediction of distant metastasis development in colorectal cancer, and could be used as a selection criterion for further therapy. Methods: Tumour CD26 expression levels were studied by immunohistochemistry using Formalin-fixed paraffin embedded (FFPE) tissues in 143 patients with CRC. Tumour CD26 expression levels were correlated with clinicopathological features of the CRC patients. The prognostic significance of tumour tissue CD26 expression levels was assessed by univariate and multivariate analyses. Result: CD26 expression levels in CRC patients with distant metastasis were significantly higher than those in non-metastatic. High expression levels of CD26 were significantly associated with advanced tumour staging. Patients with a high CD26 expression level had significantly worse overall survival than those with a lower level (p<0.001). Conclusions: The expression of CD26 was positively associated with clinicopathological correlation such as TNM staging, degree of differentiation and development of metastasis. A high CD26 expression level is a predictor of poor outcome after resection of CRC. CD26 may be a useful prognostic marker in patients with CRC. © 2014 Lam et al.published_or_final_versio

Blockade of Raf/MEK/ERK pathway by Raf265 inhibits tumor growth in colorectal cancer

Poster Session 21 - Anticancer Drugs Targeting Cell Cycle and Proliferation: abstract no. 2508Deregulation of the Raf/MEK/ERK signalling pathway is commonly observed in colorectal cancer (CRC). Since this signalling pathway plays a central role in controlling cell proliferation, apoptosis and differentiation; therefore, a number of therapeutics targeting on the Raf/MEK/ERK pathway has been established recently. Raf265 is an orally bioavailable small molecule which is a potent inhibitor of wild-type and mutant (e.g. V600E) B-raf kinases. The study of Raf265 has entered Phase I clinical trial in subjects with locally advanced or metastatic melanoma. However, its therapeutic efficacy in CRC has not been established. The objective of this study is to examine the functional effects of Raf265 in CRC cells in vitro and in vivo. CRC cell lines of different B-raf status were used for this study. Cell proliferation upon Raf265 treatment (0-50 μM) was determined using MTT cell proliferation assay. Cell cycle distribution and cell apoptosis upon Raf265 treatment (0, 1, 5, and 10 μM) were assessed by flow cytometry. Phosphorylation of molecules including MEK and ERK 1/2, and eIF4E, and expression of Mcl-1 and cyclin D1 was analyzed using Western blot. For in vivo animal studies, subcutaneous tumors were established by subcutaneous injections of 1x106 cells into nude or SCID mice, and tumor growth was monitored. Mice were sacrificed week 16 or when tumor sizes exceeded 30% of their body weight. Raf265 significantly inhibited cell proliferation in a dose-dependent manner with IC50 at 0.83 to 5.54 μM. Increased annexin V positive cells were observed with escalating dose of Raf265, which is indicative of induction of apoptosis in CRC cells. Dose-dependent increase in G1 and decrease in S phase population (cell cycle arrest at G1 phase) was also observed after treatment with Raf265. This was accompanied by the reduction of phosphor-MEK and phosphor-ERK 1/2. Down-regulation of Mcl-1 and cyclin D1, which regulate apoptosis and cell proliferation, respectively, was also observed. Intraperitoneal injections of Raf265 four times weekly demonstrated significant anti-tumor activity in established tumors of xenograft models. Immunohistochemistry demonstrated a close association between inhibition of tumor growth and inhibition of ERK 1/2 phosphorylation in the xenograft tumors, consistent with inhibition of the RAF/MEK/ERK pathway. Additional analyses of microvessel density in the same tumour sections using antimurine CD31 antibodies demonstrated significant inhibition of neovascularization in xenograft models. Furthermore, repeated sequential use of Raf265 and chemotherapy with 5-Fu and/or cisplatin demonstrated synergistic effect of inhibition of tumor growth compared with Raf265 or chemotherapy alone. These pre-clinical data demonstrate robust anti-tumour activity of Raf265 in CRC, providing the basis for exploiting its potential use as a therapeutic for Raf-driven CRC tumors.link_to_OA_fulltextThe 101st Annual Meeting of the American Association for Cancer Research (AACR 2010), San Francisco, CA., 17-21 April 2010. In AACR Meeting Abstracts, 201

Blockade of Raf/MEK/ERK pathway by Raf265 inhibits tumor growth via in colorectal cancer

Conference Theme: Advances in Technology and New Perspectives in CancerThe 17th Hong Kong International Cancer Congress (HKICC 2010), Hong Kong, 4-6 November 2010

Phenotypes developed in secretin receptor-null mice indicated a role for secretin in regulating renal water reabsorption

Aquaporin 2 (AQP2) is responsible for regulating the concentration of urine in the collecting tubules of the kidney under the control of vasopressin (Vp). Studies using Vp-deficient Brattleboro rats, however, indicated the existence of substantial Vp-independent mechanisms for membrane insertion, as well as transcriptional regulation, of this water channel. The Vp-independent mechanism(s) is clinically relevant to patients with X-linked nephrogenic diabetes insipidus (NDI) by therapeutically bypassing the dysfunctional Vp receptor. On the basis of studies with secretin receptor-null (SCTR -/-) mice, we report here for the first time that mutation of the SCTR gene could lead to mild polydipsia and polyuria. Additionally, SCTR -/- mice were shown to have reduced renal expression of AQP2 and AQP4, as well as altered glomerular and tubular morphology, suggesting possible disturbances in the filtration and/or water reabsorption process in these animals. By using SCTR-/- mice as controls and comparing them with wild-type animals, we performed both in vivo and in vitro studies that demonstrated a role for secretin in stimulating (i) AQP2 translocation from intracellular vesicles to the plasma membrane in renal medullary tubules and (ii) expression of this water channel under hyperosmotic conditions. The present study therefore provides information for at least one of the Vp-independent mechanisms that modulate the process of renal water reabsorption. Future investigations in this direction should be important in developing therapeutic means for treating NDI patients. Copyright © 2007, American Society for Microbiology. All Rights Reserved.link_to_OA_fulltex

Association between body mass index and risk of formation of breast cancer in Chinese women

OBJECTIVE: To analyse the association between body mass index (BMI) and breast cancer risk among Chinese women in Hong Kong. METHODS: We conducted a population-based case control study of breast cancer in June 2002. Standardized questionnaires concerning BMI and other anthropometric data were completed by patients at the Queen Mary Hospital (QMH). The cases were 198 women aged 24-85 years who had documented breast cancer in 1995-2000 by triple assessment criteria, and the controls were 353 women who were followed up at QMH for benign breast disease after breast cancer had been excluded by triple assessment. The controls were frequency-matched to the cases by age. RESULTS: BMI at diagnosis was positively correlated with the risk of breast cancer among postmenopausal women (p < 0.001 for trend). Also, when compared with women with a low BMI (< 19), women with a BMI of 23-27 and 27-31 had a 1.73-fold (95% confidence interval, CI, 1.04-2.86) and 2.06-fold (95% CI, 1.08-3.93) increased risk of breast cancer, respectively, after adjustment for non-anthropometric risk factors. BMI at diagnosis, however, was not related to the risk of breast cancer among premenopausal women. The odds ratios for premenopausal women with a BMI of 23-27 and 27-31 were 1.5 (95% CI, 0.82-2.71) and 1.32 (95% CI, 0.39-4.43), respectively. Furthermore, present BMI and BMI 5 years before diagnosis were poorly associated with breast cancer risk among both pre- and postmenopausal women. CONCLUSION: Weight control in obese women may be an effective measure for breast cancer prevention in postmenopausal women. © 2005 Elsevier. All rights reserved.link_to_subscribed_fulltex