Predictive value of Bcl-2 and Bax protein expression for chemotherapeutic effect in gastric cancer. A pilot study

Total saponins from Lilium lancifolium: a promising alternative to inhibit the growth of gastric carcinoma cells

Bulbus Lilii, as a medicinal and edible plant, has anti-inflammatory, anti-oxidative and immunopotentiating pharmacological activities, which seems to be therapeutic on cancer prevention. The purpose of this study was to investigate the effects of total saponins from Lilium lancifolium (TSLL) on proliferation, apoptosis and migration of human gastric carcinoma cells lines SGC-7901 and HGC-27 and its underlying mechanism. The results showed that TSLL inhibited the proliferation of gastric carcinoma cells by suppressing the level of proliferating cell nuclear antigen (PCNA) and increased p21 level. TSLL induced cells apoptosis by up-regulating expression of pro-apoptotic protein Bax and down-regulating anti-apoptotic protein Bcl-2 expression. Meanwhile, TSLL remarkably inhibited cell migration and invasion, decreased matrix metalloproteinase-2 (MMP-2) expression and increased tissue inhibitor of metalloproteinases-1 (TIMP-1) expression. Notably, TSLL had stronger anti-cancer effect on undifferentiated HGC-27 cells than differentiated SGC-7901 cells. Accordingly, TSLL might be a promising candidate to prevent and suppress the growth of gastric carcinoma cells.

XPA, XPC, and XPD Modulate Sensitivity in Gastric Cisplatin Resistance Cancer Cells

Cisplatin is an election drug widely used in clinic for the treatment of advanced gastric cancer. However, the heterogeneity of the gastric tumors and its resistance to the drugs, make in some cases the response very low and the prognosis unpredictable. In this manuscript we aim to find the molecular processes involved in cisplatin-induced apoptosis in two gastric cancer cell lines with different sensitivity to the treatment: AGS and MKN45. The apoptosis induction is higher in MKN45 than in AGS cells in response to CDDP. The intrinsic apoptotic pathway study revealed that MKN45 cells undergo degradation of Mcl-1 together with an increase of Bid and Bad levels, which results in sensitivity to CDDP. In addition, DNA repair NER pathway is impair in MKN45 cells due to low levels of XPC and the absence of translocation of XPA and XPD to the nucleus after stimuli. Altogether, these results suggest that NER and Bcl-2 protein family proteins are potential targets to improve the response to cisplatin treatment.

Molecular genetic analysis of BAX and cyclin D1 genes in patients with malignant glioma

INTRODUCTION AND OBJECTIVES

Brain tumorigenesis is a complex process involving multiple genetic alterations. Cyclin D1 and BAX genes are two of the most important regulators in controlling the normal proliferation and apoptosis of cells, respectively. In this study, we analysed the possibilities of involvement of cyclin D1 and BAX genes in the gliomagenesis.

METHODS AND RESULTS

In determining gene alterations of exon 4 of cyclin D1 gene and exon 6 of BAX gene, all samples were amplified by polymerase chain reaction (PCR) and subsequently by direct sequencing. Our results showed a frameshift mutation (G base deletion) at nucleotide 82 of codon 28 in exon 4 of the cyclin D1 gene and another frameshift mutation with a deletion of C base at nucleotide 153 of exon 6 of the BAX gene in two separate cases of a glioblastoma multiform (WHO Grade IV) sample.

CONCLUSION

These findings suggest that both cyclin D1 and BAX genes alteration are rarely found in brain tumors. However, the alteration might cause a significant effect of the normal protein production and this might contribute to the development of brain tumorigenesis in Malaysian patients.

Genetics/genomics/proteomics of gastric adenocarcinoma

Hereditary diffuse gastric cancer can be caused by epithelial cadherin mutations for which genetic testing is available. Inherited cancer predisposition syndromes including Lynch, Li-Fraumeni, and Peutz-Jeghers syndromes, can be associated with gastric cancer. Chromosomal and microsatellite instability occur in gastric cancers. Several consistent genetic and molecular alterations including chromosomal instability, microsatellite instability, and epigenetic alterations have been identified in gastric cancers. Biomarkers and molecular profiles are being discovered with potential for diagnostic, prognostic, and treatment guidance implications.

Role of BAX for outcome prediction in gastrointestinal malignancies

Our group and numerous others have shown in both preclinical and clinical studies that the proapoptotic mediator BAX may be deregulated through gene mutation or loss of protein expression, affecting resistance to chemotherapy and radiotherapy in several cancer types. However, BAX is also involved in cancer development and may related to prognosis, independently of treatment outcome. The clinical impact of BAX status in gastrointestinal malignancies remains controversial, although it is generally hypothesized that high expression may be a positive prognostic factor and predict increased efficacy of chemotherapy (with particular regard to platinum derivatives). The present review aims to provide updated information on BAX as potential prognostic and/or predictive biomarker in gastroesophageal and colorectal cancers, as well as in other less studied gastrointestinal malignancies.

Bax expression is predictive of favorable clinical outcome in chemonaive advanced gastric cancer patients treated with capecitabine, oxaliplatin, and irinotecan regimen

OBJECTIVE

Bax protein is a key mediator of apoptosis, and it might be related to chemosensitivity. The purpose of this study was to evaluate the prognostic role of Bax in patients with advanced gastric cancer treated with triplet chemotherapy COI regimen (capecitabine, oxaliplatin, and irinotecan).

METHODS

Pretreatment tissue blocks were available for 23 consecutive patients, selected for good performance status (ECOG ≤ 1) and consenting for treatment with first-line COI at a single institution. Bax levels were classified as positive or negative by immunohistochemistry (bax N20; Santa Cruz Biotechnology) and related to outcome in terms of response rate, progression-free survival, and overall survival.

RESULTS

Bax-negative and -positive samples were 26% and 74%, respectively. Bax expression was associated with significantly higher response rate (87% vs 33%), progression-free survival (8.7 vs 4.9 months, P = .016), and overall survival (23.8 vs 12.7 months, P = .025). In multivariate analysis including Bax and performance status, low Bax independently predicted worse outcome, along with suboptimal performance status.

CONCLUSIONS

In advanced gastric cancer, Bax expression was related to clinical benefit with COI regimen. Whether Bax is a prognostic or mixed prognostic/predictive factor warrants prospective confirmation. It is to be defined if Bax predicts sensitivity to platinum analogs or to whatever chemotherapy regimen.

Prognostic implications of BAX protein expression and microsatellite instability in all non-metastatic stages of primary colon cancer treated by surgery alone

PURPOSE

This study examined whether the apoptosis-related protein, BAX, or the microsatellite-instability phenotype provide prognostic information in patients with resected colon cancer.

METHODS

A total of 371 stage I-III patients that previously underwent radical surgery were included (mean follow-up 51.8 months). BAX expression was examined by immunohistochemical staining; high-frequency microsatellite instability (MSI+) was determined by assessing the specific marker, BAT26, using single-strand conformation polymorphism (SSCP)-based analysis.

RESULTS

High BAX expression was found in 66.4% of patients. MSI+ tumors were observed in 14.8% of 344 patients. Univariate analysis showed that unlike MSI, low BAX expression was significantly correlated with poor disease-specific overall survival (OS) in stages I-III (p = 0.04). Multivariate subgroup analyses revealed that unlike MSI, low BAX was an independent predictor for OS in stage II (p = 0.009); however, in stages I or III, BAX or MSI were not independent predictors of OS.

CONCLUSIONS

In stage II colon cancer treated with surgery alone, BAX protein expression may be a predictor for prognosis.

Integrative genomic analysis of small-cell lung carcinoma reveals correlates of sensitivity to bcl-2 antagonists and uncovers novel chromosomal gains

Cancer is a highly heterogeneous disease in terms of the genetic profile and the response to therapeutics. An early identification of a genomic marker in drug discovery may help select patients that would respond to treatment in clinical trials. Here we suggest coupling compound screening with comparative genomic hybridization analysis of the model systems for early discovery of genomic biomarkers. A Bcl-2 antagonist, ABT-737, has recently been discovered and shown to induce regression of solid tumors, but its activity is limited to a fraction of small-cell lung carcinoma (SCLC) models tested. We used comparative genomic hybridization on high-density single-nucleotide polymorphism genotyping arrays to carry out a genome-wide analysis of 23 SCLC cell lines sensitive and resistant to ABT-737. The screen revealed a number of novel recurrent gene copy number abnormalities, which were also found in an independent data set of 19 SCLC tumors and confirmed by real-time quantitative PCR. A previously unknown amplification was identified on 18q and associated with the sensitivity of SCLC cell lines to ABT-737 and another Bcl-2 antagonist. The region of gain contains Bcl-2 and NOXA, two apoptosis-related genes. Expression microarray profiling showed that the genes residing in the amplified region of 18q are also overexpressed in the sensitive lines relative to the resistant lines. Fluorescence in situ hybridization analysis of tumors revealed that Bcl-2 gain is a frequent event in SCLC. Our findings suggest that 18q21-23 copy number will be a clinically relevant predictor for sensitivity of SCLC to Bcl-2 family inhibitors. The 18q21-23 genomic marker may have a broader application in cancer because Bcl-2 is associated with apoptosis evasion and chemoresistance.

Effects of Chinese herbal recipe Weichang'an in inducing apoptosis and related gene expression in human gastric cancer grafted onto nude mice

OBJECTIVE

To investigate the mechanism of Chinese herbal recipe Weichang'an (WCA) in inducing cell apoptosis of human gastric cancer grafted onto nude mice.

METHODS

The high performance liquid chromatography was used for monitoring the stability of WCA. A human gastric cancer cell line SGC-7901 grafted in nude mouse was used as the animal model. The mice were divided into untreated group and two experimental groups. Animals in the two experimental groups received either WCA over a 34-day period or 5-fluorouracil (5-FU) over a 6-day period starting at the 8th day after grafting. Animals in the untreated group received normal saline on an identical schedule. Animals were killed 41 days after being grafted. To assess the effect of the treatment on tumor, the tumor weight was determined by the electron balance immediately after the animals were killed. SP immunohistochemical method was used to detect the expression of proliferating cell nuclear antigen (PCNA) in grafts. Apoptotic indices (AI) of the tumor cells were examined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling (TUNEL) method. SP method was also used to detect the expressions of cleaved caspase-3, caspase-8 and caspase-9. SYBR green dye I real-time quantitative polymerase chain reaction (real-time quantitative [corrected] PCR) was used to assess the related gene alterations in mRNA level. The expressions of phospho-Stat3 (Tyr705) and bcl-2 proteins were detected by using SP method.

RESULTS

Compared with the untreated group, tumor growth was significantly inhibited by treatment of WCA or 5-FU (P<0.01, respectively). The tumor inhibition rate in the WCA-treated group was 48.70% and that in the 5-FU-treated group was 60.10%. The average labeling index (LI) for PCNA in the WCA-treated group and 5-FU-treated group was significantly decreased as compared with that in the untreated group, respectively. The AI of human gastric cancer grafted in the nude mice detected by using TUNEL method was significantly increased to (9.72+/-4.51)% in the WCA-treated group, while it was (2.45+/-1.37)% in the untreated group. 5-FU-treated group was also found a significantly increased AI compared with the untreated group. The expressions of cleaved caspase-3 and caspase-9 in the WCA-treated group and 5-FU-treated group were significantly increased as compared with those in the untreated group. But caspase-8 showed no significant alteration either in the WCA-treated group or in the 5-FU-treated group. The expression levels of Stat3 (2(-)delta delta C(T))=0.16) and bcl-2 (2(-)delta delta C(T))=0.10) detected by using real-time quantitative [corrected] PCR were lower in the WCA-treated group than those in the untreated group. The expressions of phospho-Stat3 (Tyr705) and bcl-2 in the WCA-treated group were significantly decreased as compared with those in the untreated group.

CONCLUSIONS

Chinese herbal recipe WCA can inhibit gastric cancer cell SGC-7901 growth in vivo, induce gastric cancer cell apoptosis and suppress the cell proliferation. WCA induces apoptosis through the caspase-9 and caspase-3 pathway in vivo. Its mechanism might be involved in the down-regulation of Stat3 and bcl-2 genes.

Sanguinarine overcomes P-glycoprotein-mediated multidrug-resistance via induction of apoptosis and oncosis in CEM-VLB 1000 cells

Permeability-glycoprotein (Pgp) positive cells are known to be encoded by the multidrug-resistance gene (MDR1), and characterized by a reduced ability to accumulate drugs. The vinblastin-resistant, Pgp positive CEM-VLB 1000 and its wild type (Pgp-negative and vinblastin-sensitive) counterpart CEM-T4 human leukemia cells, when treated with the alkaloid sanguinarine, were both found to undergo apoptosis at concentrations of 1.5 microg/ml and oncosis/blister cell death (BCD) at concentrations of 12.5 microg/ml. The aim of this study was to assess the ability of sanguinarine to overcome Pgp-mediated multidrug-resistance (MDR), and also to characterize the cell death processes of apoptosis and oncosis (or bimodal cell death) induced by sanguinarine in MDR cells. The cell death processes of apoptosis and oncosis in CEM-VLB 1000 and CEM-T4 cell lines were found to be qualitatively similar when assessed by light microscopy, terminal deoxynucleotidyl transferase (TdT) end-labeling, annexin-V-binding, trypan blue exclusion and western blot analysis. Western blotting revealed an increase in the Bax/Bcl-2 ratio and activation of caspase-3 in apoptosis but not oncosis in both cell lines. The Pgp-positive CEM-VLB 1000 cells and their wild type CEM-T4 cells were both equally sensitive to sanguinarine. Thus, sanguinarine may overcome the phenomenon of Pgp-mediated MDR by inducing apoptosis through increasing the Bax/Bcl-2 ratio and activating caspase-3, and oncosis, which involved neither.

Biological markers as a predictor for response and prognosis of unresectable gastric cancer patients treated with irinotecan and cisplatin

BACKGROUND

Previously we reported that immunohistochemical examination of p53, bcl-2, glutathione S-transferase-pi (GST-pi), thymidylate synthase (TS) and vascular endothelial growth factor (VEGF) in biopsy samples was a useful method for predicting clinical outcome of gastric cancer patients treated with 5-fluorouracil and cisplatin. Here, we investigated if these biological markers can predict chemoresponse and survival of unresectable gastric cancer patients treated with irinotecan and cisplatin.

METHODS

The subjects were 55 unresectable gastric cancer patients treated with irinotecan (70 mg/m(2), Days 1 and 15) and cisplatin (80 mg/m(2), Day 1). Expression of p53, bcl-2, VEGF was examined immunohistochemically in biopsy samples.

RESULTS

The overall response rate and the median survival time were 55% (30/55) and 321 days, respectively. Thirty patients with intestinal-type adenocarcinoma survived longer than 25 patients with diffuse-type (median survival time: 446, 259 days, P = 0.013). The favorable phenotypes for chemoresponse were p53-negative, bcl-2-negative and VEGF-positive, which were in accordance with previous findings. The response rate was significantly correlated with the total number of these favorable phenotypes (P = 0.043). The 39 patients having 2 or 3 favorable phenotypes (p53-negative, bcl-2-negative and VEGF-positive) survived longer than the remaining 16 patients (median survival time: 444, 259 days, P = 0.021). In the Cox model, the number of the favorable phenotypes showed a tendency to correlate with survival after adjustment for potentially prognostic factors such as histological type or performance status (P = 0.070).

CONCLUSIONS

Immunohistochemical examination of biological markers may be useful in predicting the clinical outcome of unresectable gastric cancer patients treated with irinotecan and cisplatin.

Bax and Bcl-2 protein expression in gastric precancerous lesions: immunohistochemical study

BACKGROUND AND AIMS

Bcl-2 protein prolongs cell survival in the face of classical apoptotic stimuli, and is considered to be a suppressor of apoptosis. Bax plays a key role in apoptosis by accelerating cell death after an apoptotic stimulus. The aim of our study was to determine the roles of the Bax proapoptotic gene and the Bcl-2 antiapoptotic gene in the carcinogenesis of gastric cancer.

METHODS

One hundred and forty-five gastric biopsy specimens of chronic gastritis, atrophic gastritis, intestinal metaplasia and gastric dysplasia were studied. Using immunohistochemical methods, Bax and Bcl-2 protein expression was observed.

RESULTS

Bax was expressed in epithelial cells in all cases of chronic gastritis. Bax was not detected in 26% of specimens of atrophic gastritis. As intestinal metaplasia develops, Bax is further suppressed. In biopsy samples with dysplasia, Bax expression was demonstrated only in 12% of biopsy samples. Although Bcl-2 protein was not detected in chronic gastritis, aberrant expression was found in gastric epithelial intestinal metaplasia and dysplasia.

CONCLUSIONS

The suppression of Bax and overexpression of Bcl-2 protein is an early event in gastric tumorigenesis, before gastric dysplastic changes occur.

Promoting apoptosis as a strategy for cancer drug discovery

Apoptosis is deregulated in many cancers, making it difficult to kill tumours. Drugs that restore the normal apoptotic pathways have the potential for effectively treating cancers that depend on aberrations of the apoptotic pathway to stay alive. Apoptosis targets that are currently being explored for cancer drug discovery include the tumour-necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptors, the BCL2 family of anti-apoptotic proteins, inhibitor of apoptosis (IAP) proteins and MDM2.

Death receptors in chemotherapy and cancer

Apoptosis, the cell's intrinsic death program, is a key regulator of tissue homeostasis. An imbalance between cell death and proliferation may result in tumor formation. Also, killing of cancer cells by cytotoxic therapies such as chemotherapy, gamma-irradiation or ligation of death receptors is predominantly mediated by triggering apoptosis in target cells. In addition to the intrinsic mitochondrial pathway, elements of death receptor signaling pathways have been implied to contribute to the efficacy of cancer therapy. Failure to undergo apoptosis in response to anticancer therapy may lead to resistance. Also, deregulated expression of death receptor pathway molecules may contribute to tumorigenesis and tumor escape from endogenous growth control. Understanding the molecular events that regulate apoptosis induced by anticancer therapy and how cancer cells evade apoptosis may provide new opportunities for pathway-based rational therapy and for drug development.

Sanguinarine induces bimodal cell death in K562 but not in high Bcl-2-expressing JM1 cells

Our previous studies with low Bcl-2-expressing K562 cells have shown that, when treated with the putative anti-cancer drug sanguinarine, concentrations of 1.5 microg/ml induced the morphology of apoptosis or programmed cell death (PCD), while concentrations of 12.5 microg/ml induced a morphology of blister formation or blister cell death (BCD). To elucidate the possible role of Bcl-2 in this dual cell death modality induced by sanguinarine, K562 and the high Bcl-2-expressing JM1 cells were treated with sanguinarine concentrations of 1.5 microg/ml and 12.5 microg/ml respectively, and multiple parameters of their effects were studied using light and electron microscopy, terminal deoxynucleotidyl transferase (TdT) end-labeling, 51Cr release, trypan blue exclusion, propidium iodide exclusion, and annexin-V binding. In general, we found that, while K562 cells underwent PCD and BCD when treated with sanguinarine, JM1 cells failed to undergo either PCD or BCD under the same experimental conditions. Thus, the over-expression of anti-apoptotic Bcl-2 may have prevented sanguinarine from inducing PCD and BCD in JM1 cells. These results indicate that the resistance of JM1 cells to the alkaloid sanguinarine may have been due to an anti-BCD role played by Bcl-2, in addition to its widely reported anti-apoptotic role.

Bcl-2 expression in synovial fibroblasts is essential for maintaining mitochondrial homeostasis and cell viability

The regulation of proliferation and cell death is vital for homeostasis, but the mechanism that coordinately balances these events in rheumatoid arthritis (RA) remains largely unknown. In RA, the synovial lining thickens in part through increased proliferation and/or decreased synovial fibroblast cell death. Here we demonstrate that the anti-apoptotic protein, Bcl-2, is highly expressed in RA compared with osteoarthritis synovial tissues, particularly in the CD68-negative, fibroblast-like synoviocyte population. To determine the importance of endogenous Bcl-2, an adenoviral vector expressing a hammerhead ribozyme to Bcl-2 (Ad-Rbz-Bcl-2) mRNA was employed. Ad-Rbz-Bcl-2 infection resulted in reduced Bcl-2 expression and cell viability in synovial fibroblasts isolated from RA and osteoarthritis synovial tissues. In addition, Ad-Rbz-Bcl-2-induced mitochondrial permeability transition, cytochrome c release, activation of caspases 9 and 3, and DNA fragmentation. The general caspase inhibitor zVAD.fmk blocked caspase activation, poly(ADP-ribose) polymerase cleavage, and DNA fragmentation, but not loss of transmembrane potential or viability, indicating that cell death was independent of caspase activation. Ectopically expressed Bcl-xL inhibited Ad-Rbz-Bcl-2-induced mitochondrial permeability transition and apoptosis in Ad-Rbz-Bcl-2-transduced cells. Thus, forced down-regulation of Bcl-2 does not induce a compensatory mechanism to prevent loss of mitochondrial integrity and cell death in human fibroblasts.

Escaping cell death: survival proteins in cancer

Defects in apoptosis signaling pathways are common in cancer cells. Such defects may play an important role in tumor initiation because apoptosis normally eliminates cells with damaged DNA or dysregulated cell cycle, i.e., cells with increased malignant potential. Moreover, impaired apoptosis may enhance tumor progression and promote metastasis by enabling tumor cells to survive the transit in the bloodstream and to grow in ectopic tissue sites lacking the otherwise required survival factors. Finally, raised apoptosis threshold may have deleterious consequences by rendering cancer cells resistant to various forms of therapy. The intensive apoptosis research during the past decade has resulted in the identification of several proteins which may promote tumorigenesis by inhibiting apoptosis. Of special relevance in human cancer are those commonly expressed in primary tumors and functioning at the common part of the signaling pathway leading to apoptosis. Proteins fulfilling these criteria include antiapoptotic members of the Bcl-2 protein family, heat shock proteins, Hsp70 and Hsp27, as well as survivin, the novel cancer-associated member of the inhibitor of apoptosis protein family. Understanding the molecular mechanisms of action of these proteins may offer novel modes of rationally and selectively manipulating the sensitivity of cancer cells to therapy.