The expression of GST isoenzymes and p53 in non-small cell lung cancer. Folia Histochem Cytobiol. 2010;48:122-127. [PMID: 20529827 DOI: 10.2478/v10042-008-0084-6]

Quinacrine inhibits GSTA1 activity and induces apoptosis through G1/S arrest and generation of ROS in human non-small cell lung cancer cell lines

Background: Quinacrine (QC) is popular for its anti-malarial activity. It has been reported exhibiting anti-cancerous properties by suppressing nuclear factor-κB and activating p53 signaling; however, its effect on cellular pathways in human non-small cell lung cancer (NSCLC) has not been studied.

Materials and Methods: Binding of QC with GSTA1 was studied computationally as well as through GST activity assay kit. Cell viability, cell cycle and mitochondrial membrane potential activity were studied using flow cytometry. RT-PCR and western blot were carried out to understand the involvement of various genes at their mRNA as well as protein level.

Results: QC inhibited the activity of GSTA1 approximately by 40–45% which inhibits cell survival and promotes apoptosis. QC reduced viability of NSCLC cells in a dose-dependent manner. It also causes nuclear fragmentation, G₁/S arrest of cell cycle and ROS generation; which along with disruption of mitochondrial membrane potential activity leads to apoptotic fate.

Conclusions: Results revealed, QC has promising anti-cancer potential against NSCLC cells via inhibition of GSTA1, induction of G₁/S arrest and ROS mediated apoptotic signaling.

Effects of zerumbone on proliferation and apoptosis of esophageal cancer cells and on P53 and Bcl-2 expression levels

The effects of zerumbone on the proliferation and apoptosis of esophagus cancer cells and on the P53 and Bcl-2 expression levels were studied. The esophagus cancer EC-109 cells were cultured and inoculated. The effect of zerumbone on proliferation of EC-109 cells was detected via the Cell Counting Kit-8 (CCK-8) method. Cell apoptosis was detected via TdT-mediated dUTP nick end-labeling (TUNEL) staining. Moreover, the mRNA expression levels of P53 and Bcl-2 were detected via reverse transcription-polymerase chain reaction (RT-PCR), and the protein expression levels of P53 and Bcl-2 were evaluated via western blotting. CCK-8 detection results showed that compared with control group, zerumbone in different concentrations could inhibit the activity of EC-109, and the proliferation inhibition rate was significantly increased in a concentration-dependent manner with the increase of concentration. TUNEL staining showed that cell apoptosis gradually occurred in administration group, and the number of apoptotic cells was increased in a concentration-dependent manner with the increase of concentration. RT-PCR detection results showed that the mRNA expression level of P53 in administration group was significantly increased compared with that in control group, but that of Bcl-2 was significantly decreased. Western blotting showed that the protein expression level of Bcl-2 in administration group in different concentrations was significantly increased with the increase of zerumbone concentration, but that of Bcl-2 was significantly decreased in a concentration-dependent manner. Zerumbone can inhibit the proliferation and induce apoptosis of esophageal cancer EC-109 cells, and its induction of apoptosis may be realized through upregulating the mRNA expression of P53 and downregulating the mRNA expression of Bcl-2, and upregulating the protein expression of P53 and downregulating the protein expression of Bcl-2.

Polymorphisms and Protein Expressions of Glutathione S-Transferase M1 and T1 in Non-Small Cell Lung Cancer

Objectives

The deletion polymorphisms of glutathione S-transferase (GST) GSTM1 and GSTT1 genes result in the absence of the corresponding protein, which decreases the detoxification of carcinogens. Studies evaluating polymorphisms and protein expressions in the same patients are limited. Therefore, in this study, we aimed to investigate the association between polymorphisms and protein expressions of GSTM1 and GSTT1 in lung tissues of patients with non-small cell lung cancer (NSCLC).

Materials and Methods

For protein expression and gene deletion studies, tumor and surrounding tumor free (normal) tissue of 33 patients with NSCLC were used. In paraffin-embedded tissues, immunohistochemistry was used to detect protein expressions, and multiplex polymerase chain reaction amplification was used to identify gene deletions.

Results

GSTM1 and GSTT1 protein expressions were not detected in patients with GSTM1 and GSTT1 gene deletions, whereas protein expressions were detected in lung tissues of all patients carrying GSTM1 and GSTT1 genes. The protein expression level of GSTT1 was 2.0-fold higher in tumors of patients lacking GSTM1 genes than those with GSTM1 genes (p=0.018). Protein expression of GSTM1 was statistically higher in tumor tissues than in normal tissues of patients with GSTM1 genes (p=0.001).

Conclusion

These results show that a) there is an association between gene deletions and protein expressions of GSTM1 and GSTT1 in patients with NSCLC, b) in the absence of GSTM1 genes, enhancement of expression of GSTT1 in tumors is likely to show that GSTT1 increases its capacity to detoxify the toxic electrophiles in tumors, and c) GSTM1 protein expression is higher in tumors compared with normal lung tissues of patients with NSCLC.

Chemical Reactivity Window Determines Prodrug Efficiency toward Glutathione Transferase Overexpressing Cancer Cells

Glutathione transferases (GSTs) are often overexpressed in tumors and frequently correlated to bad prognosis and resistance against a number of different anticancer drugs. To selectively target these cells and to overcome this resistance we previously have developed prodrugs that are derivatives of existing anticancer drugs (e.g., doxorubicin) incorporating a sulfonamide moiety. When cleaved by GSTs, the prodrug releases the cytostatic moiety predominantly in GST overexpressing cells, thus sparing normal cells with moderate enzyme levels. By modifying the sulfonamide it is possible to control the rate of drug release and specifically target different GSTs. Here we show that the newly synthesized compounds, 4-acetyl-2-nitro-benzenesulfonyl etoposide (ANS-etoposide) and 4-acetyl-2-nitro-benzenesulfonyl doxorubicin (ANS-DOX), function as prodrugs for GSTA1 and MGST1 overexpressing cell lines. ANS-DOX, in particular, showed a desirable cytotoxic profile by inducing toxicity and DNA damage in a GST-dependent manner compared to control cells. Its moderate conversion of 500 nmol/min/mg, as catalyzed by GSTA1, seems hereby essential since the more reactive 2,4-dinitrobenzenesulfonyl doxorubicin (DNS-DOX) (14000 nmol/min/mg) did not display a preference for GSTA1 overexpressing cells. DNS-DOX, however, effectively killed GSTP1 (20 nmol/min/mg) and MGST1 (450 nmol/min/mg) overexpressing cells as did the less reactive 4-mononitrobenzenesulfonyl doxorubicin (MNS-DOX) in a MGST1-dependent manner (1.5 nmol/min/mg) as shown previously. Furthermore, we show that the mechanism of these prodrugs involves a reduction in GSH levels as well as inhibition of the redox regulatory enzyme thioredoxin reductase 1 (TrxR1) by virtue of their electrophilic sulfonamide moiety. TrxR1 is upregulated in many tumors and associated with resistance to chemotherapy and poor patient prognosis. Additionally, the prodrugs potentially acted as a general shuttle system for DOX, by overcoming resistance mechanisms in cells. Here we propose that GST-dependent prodrugs require a conversion rate "window" in order to selectively target GST overexpressing cells, while limiting their effects on normal cells. Prodrugs are furthermore a suitable system to specifically target GSTs and to overcome various drug resistance mechanisms that apply to the parental drug.

Correlation between metabolic enzyme GSTP1 polymorphisms and susceptibility to lung cancer

The aim of the present study was to determine the frequency distribution and characteristics of polymorphic alleles and genotypes in glutathione S-transferase π 1 (GSTP1) exon 5, and to explore the correlation between GSTP1 exon 5 polymorphisms and susceptibility to lung cancer using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Patients were diagnosed with lung cancer from May 2006 to October 2008 by postoperative pathological examination. A total of 150 patients, including 115 males and 35 females, aged 31-76 years (mean, 57.1 years) were enrolled. The control group consisted of 152 healthy volunteers who received physical examination at outpatient clinics. Genomic DNA was extracted from the peripheral venous blood of the 302 subjects, and the GSTP1 genotype was determined by PCR-RFLP and restricted enzyme digestion of PCR products. GSTP1 polymorphisms were analyzed in the 302 subjects. The C and G allele frequencies of GSTP1 in the control and lung cancer groups showed no significant difference (P=0.135); the frequencies of three different genotypes, A/A, A/G and G/G, of GSTP1 in the control and lung cancer groups exhibited no significant differences between the two groups (P=0.223). GSTP1 genotype frequencies in the study population fitted the Hardy-Weinberg equilibrium, demonstrating that the genotype results of this study conform to this genetic law. Overall, 50.7% of the subjects in the lung cancer group carried the non-A/A genotype of GSTP1, which was higher than the 43.4% of the control group. The risk of lung cancer in subjects with the non-A/A genotype was 1.43-fold higher than that in those with the A/A genotype, but no statistical significance was found (P=0.138). GSTP1 exon 5 polymorphisms were demonstrated to be associated with lung cancer susceptibility on the whole. However, stratified analysis suggested the correlation of GSTP1 exon 5 polymorphisms with lung squamous cell carcinoma risk, and that exon 5 polymorphisms might increase the risk of lung squamous cell carcinoma. Exon 5 GSTP1 polymorphisms were not found to be a strong influencing factor in lung cancer risk, but may play a certain role.

Clinical significance of P53 and Ki67 expression in gastric cancer

AIM: To investigate the correlation of P53 and Ki67 protein expression with the clinicopathological parameters in gastric cancer.

METHODS: A total of 1 107 surgical specimens of gastric cancer were collected from the Fuzhou General Hospital of Nanjing Military Command, The expression of P53 and Ki67 was examined by immunohistochemistry in 775 gastric cancer specimens taken from patients with complete clinical data.

RESULTS: The positive rates of P53 and Ki67 protein expression were 46.84% and 78.97%, respectively. Higher positive rates of P53 and Ki67 protein expression were noted in intestinal-type gastric cancer than in diffuse-type gastric cancer (54.7% vs 38.0%, 86.0% vs 70.0%, both P < 0.05) and in well-differentiated cancer than in poorly-differentiated cancer (54.7 vs 35.4%, 87.0% vs 67.2%, both P < 0.05). A higher positive rate of P53 protein expression was noted in gastroesophageal junction (GEJ) cancer than in gastric cancer (53.7% vs 41.9%, P < 0.05) and in cancer without distant metastasis than in that with distant metastasis (49.0% vs 30.3%, P < 0.05). A higher positive rate of Ki67 protein expression was noted in invasive cancer than in less invasive cancer ( 80.3% vs 60.4%, P < 0.05) and in cancer with lymph node metastasis than in that without lymph node metastasis (81.4% vs 72.6 %, P < 0.05).

CONCLUSION: P53 and Ki67 protein expression might be associated with the development, invasion, and metastasis of gastric cancer, and can be used to evaluate the malignant behavior and prognosis of gastric cancer.