In vivo expression of p53 and Bcl-2 and their role in programmed cell death in premalignant and malignant lung lesions

Amelioration of Combination of Paclitaxel and Di Allyl Sulfide on the Alterations of Bcl2, P53 and Apoptosis Changes Against 7,12 Di Methyl Benz (A) Anthracene Induced Skin Cancer in Experimental Animals

The purpose of this study was to investigate the Bcl2, P⁵³ and apoptosis changes against skin cancer in experimental animals. Skin cancer is the most common form of human cancer. It is estimated that over 1 million new cases occur annually. The annual rates of all forms of skin cancer are increasing each year, representing a growing public concern. It has also been estimated that nearly half of all Americans who live to age 65 are likely to develop skin cancer at least once. Skin cancer was induced in rats by Di Methyl Benz (a) Anthracene at the dosage of DMBA (5 µg) per animal, three times a week for 28 weeks after conformation of skin cancer treated with Paclitaxel and Di allyl sulfide for 30 days. The levels of Bcl2 gene expression were significantly decreased and P⁵³gene expression were markedly increased in Paclitaxel and Di allyl sulfide treated animals when compared with cancer bearing animals. The treatment with combination of Paclitaxel and Di allyl sulfide effectively reduced Bcl2 protein expression and also increased P⁵³gene expression. Moreover, the levels of Bcl2 and P⁵³ a good indicators of restoring the skin architecture, were also reversed in skin damage subjects after treatment with the herbal compounds preparation. So, from the obtained results it is concluded that a combination of Paclitaxel and Di allyl sulfide is capable of restoring the skin architecture and can also increase the apoptosis activities in skin cancer rats.

Effect of TW37 on the growth of H1975 EGFR‑TKI‑resistant lung cancer cells and its underlying mechanisms

Previous studies have suggested that the B‑cell lymphoma 2 (Bcl‑2) inhibitor, TW37, may induce apoptosis of the non‑small cell lung cancer cell line, H1975/epidermal growth factor receptor‑tyrosine kinase inhibitor (EGFR‑TKI), which exhibits secondary resistance to EGFR‑TKI. However, the effects of TW37 on H1975/EGFR‑TKI cells remain unclear. The aim of the present study was to investigate the effects of TW37 on the growth of H1975/EGFR‑TKI cells and explore the underlying mechanisms. An in vitro study was performed, whereby H1975/EGFR‑TKI cells were treated with serially increasing concentrations of TW37. MTT, flow cytometry, migration and transwell invasion assays were preformed to investigate the proliferation, apoptosis, migration and invasion of H1975/EGFR‑TKI cells, respectively. In addition, reverse transcription‑polymerase chain reaction and western blot analyses were performed to detect the mRNA and protein expression levels of apoptosis‑associated factors, respectively. An enzyme‑linked immunosorbent assay was performed to detect phosphatidylinositol [3,4,5] tris‑phosphate (PIP3) expression. The results suggested that the mRNA and protein expression levels of Bcl‑2 were significantly decreased in TW37‑treated cells when compared with the untreated control group. Following treatment with TW37, the proliferation, migration and invasion ability of H1975/EGFR‑TKI cells decreased in a dose‑dependent manner, while the percentage of apoptotic cells increased. In addition, the results demonstrated that TW37 reduced the expression of PIP3 and the phosphorylation of AKT serine/threonine kinase 1 (AKT) in H1975/EGFR‑TKI cells in a dose‑dependent manner. In conclusion, TW37 inhibited H1975/EGFR‑TKI cell growth and induced cell apoptosis potentially via suppression of AKT signaling pathway activation.

Effect of β-sitosterol on the expression of HPV E6 and p53 in cervical carcinoma cells

AIM OF THE STUDY

In the absence of effective therapeutic strategies, cervical carcinoma continues to be second on the list of mortality rates of malignant tumours found in women. We investigated the effects of β -sitosterol, a natural product isolated from traditional Chinese herbs, on Caski and HeLa cervical carcinoma cells.

MATERIAL AND METHODS

Morphological changes were examined by light microscopy. Ultrastructures of Caski and HeLa cells treated with 20 µmol/l β-sitosterol were documented by scanning electron microscopy and transmission electron microscopy. Changes in mRNA and protein expression were quantified respectively using Real-Time qPCR and western blot methods.

RESULTS

Treatment of Caski and HeLa cells with β-sitosterol resulted in reduced expression of PCNA, indicative of an inhibitory effect on cell proliferation. This was associated with increased p53 mRNA levels and decreased amounts of HPV E6 transcripts. Expression of p53 and HPV E6 proteins followed a similar trend as that observed for the corresponding transcripts. Caski and HeLa cells treated with β-sitosterol exhibited loss of cell surface microvilli, increased electron density of cell membrane, and decreased organelles.

CONCLUSIONS

In conclusion, treatment of Caski and HeLa cells with β-sitosterol significantly suppressed the expression of genes involved in cell proliferation and oncogenic transformation, while augmenting the expression of genes involved in apoptosis and tumour suppression. Ultrastuctural characterisation of Caski and HeLa cells treated with β-sitosterol further confirmed the anti-proliferative and anti-cancer activity of this natural product isolated from traditional Chinese herbs.

Bcl-2-enhanced efficacy of microtubule-targeting chemotherapy through Bim overexpression: implications for cancer treatment

Bcl-2 is commonly overexpressed in tumors, where it is often associated with unfavorable outcome. However, it has also been linked to a favorable sensitivity to microtubule-targeting agents (MTAs). We show that Bcl-2-overexpressing lung and breast cancer cells were more sensitive to both paclitaxel and vinorelbine. Bcl-2 over-expression also significantly potentiated in vivo efficacy of paclitaxel, in terms of tumor volume decrease and survival benefits, in models of nude mice bearing lung cancer xenografts. To further investigate this favorable effect of Bcl-2, a genomic approach was taken. It revealed that Bcl-2 overexpression induced up-regulation of the proapoptotic protein Bim in lung cancer cells and that, conversely, Bcl-2 silencing decreased Bim expression level. A gene regulation study implicated the transcription factor Forkhead box-containing protein, class O3a in Bim up-regulation. Lastly, we show that Bim was responsible for MTA-triggered lung cancer cell death through a dynamin-related protein 1-mediated mitochondrial fragmentation. The Bcl-2-governed Bim induction evidence offers for the first time an explanation for the favorable higher sensitivity to treatment shown by Bcl-2-overexpressing cells. We suggest that Bim could be a powerful predictive factor for tumor response to MTA chemotherapy. Our data also give new insight into some failures in the efficacy of therapies targeted against Bcl-2.

Phase I trial of oblimersen (Genasense®) and gemcitabine in refractory and advanced malignancies

BACKGROUND

Overexpression of Bcl-2 is associated with worse prognosis for a number of cancer types. The present study was designed to determine the maximum tolerated dose (MTD) of oblimersen (antisense Bcl-2) and gemcitabine when administered to patients with refractory malignancies.

MATERIALS AND METHODS

Sixteen patients with advanced solid tumors refractory to standard therapies were treated with escalating doses of oblimersen continuous, 120-h intravenous infusion given every 14 days, with a fixed-dose-rate intravenous infusion of gemcitabine administered on day 5 of each cycle. Serial plasma samples were collected to calculate the pharmacokinetics of oblimersen and gemcitabine, and also to measure the effect of oblimersen on Bcl-2 expression.

RESULTS

7 women and 9 men, median age 55 years (range 35-74 years), received a 5-day infusion of oblimersen at dose levels of 5 mg/kg/day (n = 4) or 7 mg/kg/day (n = 12). On the 5th day of the infusion, gemcitabine was given at 10 mg/m(2)/h for a total dose of 1,000 mg/m(2) (n = 7; cohorts I and II), 1,200 mg/m(2) (n = 3; cohort III), or 1,500 mg/m(2) (n = 6; cohort IV). Edema was the dose-limiting toxicity (DLT), necessitating expansion of cohort IV. No subsequent DLTs were noted. Thus, the maximum planned doses were well tolerated, and a formal MTD was not determined. Most hematologic toxicities were grade 1 or 2. There was low-grade fatigue, nausea/vomiting, and myalgias/arthralgias. Oblimersen C(ss) and AUC increased in relation to the dose escalation, but gemcitabine triphosphate levels did not correlate well with dose. There were no objective responses, though 5 patients had stable disease. A >75% reduction in Bcl-2 expression in peripheral blood mononuclear leucocytes was seen more frequently in patients who achieved stable disease than in progressing patients.

CONCLUSIONS

The maximal planned dose levels of oblimersen and gemcitabine in combination were well tolerated. Only one DLT (edema) occurred. There was a correlation between Bcl-2 reduction and stable disease. The recommended doses of the drugs for future studies are 7 mg/kg/day of oblimersen on days 1-5, and gemcitabine 1,500 mg/m(2) on day 5, every two weeks.

Expression of p53 protein and the apoptotic regulatory molecules Bcl-2, Bcl-XL, and Bax in locally advanced squamous cell carcinoma of the lung

OBJECTIVE

Bcl-2 family of proteins plays a critical role in the regulation of apoptosis. This pathway may be dysregulated leading to an altered ratio of pro- and anti-apoptotic molecules, hence rendering cells resistant to chemotherapy. The objective of this study was to understand the role of Bcl-2 family members in mediation of apoptosis in squamous cell carcinoma of the lung.

RESULTS

Bronchoscopically obtained lung biopsies from 30 cases of histologically proven squamous cell carcinoma of the lung in stage III were assessed for the expression of Bcl-2, Bcl-XL, and Bax at the mRNA and protein levels by semi-quantitative reverse transcription (RT-PCR) and immunohistochemistry. The apoptotic index (AI) was determined by the TUNEL assay. The AI ranged from <0.1 to 6.0% with a median of 1.3%. Bcl-2/Bax transcript ratio ranged from 1.5 to 4.5 and Bcl-XL/Bax from 1.3 to 4.0 indicating increased levels of anti-apoptotic molecules at the transcript levels. There was no correlation of the mRNA levels to the apoptotic index. (Wilcoxon-signed rank test.) Immunohistochemistry for proteins revealed that majority of the tumors were Bax predominated. p53 protein immunohistochemical expression was present in 66% cases. The apoptotic index correlated with Bax expression (P < 0.05; Wilcoxon-signed rank test and chi-square test) but not with Bcl-2, Bcl-XL or p53 levels. There was a positive association of p53 with Bax expression.

CONCLUSION

The results of this study indicate that in locally advanced squamous cell carcinoma of the lung, Bax protein is up regulated and determines the level of apoptosis.

Non-small lung cancer cells are prime targets for p53 gene transfer mediated by a recombinant adeno-associated virus type-2 vector

In this study, we elucidated the potential of recombinant adeno-associated virus type-2 (rAAV-2) vectors for lung cancer gene therapy. Cell lines of the three major histological subtypes of non-small cell lung cancer (NSCLC) were highly susceptible for rAAV-2 showing transduction rates between 63.4 and 98.9%. In contrast, cell lines of small cell carcinomas were resistant to rAAV-2 infection. For restoration of p53 function in p53 deficient NSCLC, a rAAV-2 vector was constructed containing wt p53 cDNA. Following transduction with rAAV-p53, cell growth of all NSCLC cell lines was significantly reduced in a dose-dependent manner between 44 and 71.7% in comparison with rAAV-GFP transduced cells. The reduction of tumor cell growth was associated with increased apoptosis. Adding cisplatin to rAAV-p53-infected cells led to a significant growth inhibition between 81 and 91% indicating a synergistic effect between cisplatin and rAAV-p53. Interestingly, the tumor cells surviving cisplatin and rAAV-p53 treatment were inhibited in their ability to form colonies as reflected by a reduction of colony growth between 57 and 90.4%. In conclusion, rAAV-2 vectors exhibit a strong tropism for NSCLC. Successful inhibition of tumor cell growth following transduction with a rAAV-p53 vector underlines the potential role of rAAV-2 in cancer gene therapy.

p53 and Bcl-2 Protein Expression and Its Relationship with Prognosis in Small-Cell Lung Cancer

Small-cell lung cancer (SCLC) has a poor prognosis despite good initial response to chemotherapy. Therefore, it is important to identify molecular markers that might influence survival and serve as potential therapeutic targets. Previous studies have demonstrated immunohistochemical expression of p53 and Bcl-2 in approximately 40%-90% and 55%-90% of patients with SCLC, respectively, but its relationship with prognosis remains controversial. To determine the correlation between the expression of p53 and Bcl-2 and disease-free survival, age (< 70 vs. >or= 70 years), sex, clinical stage (limited vs. extensive), performance status (World Health Organization stages 0-4), and weight loss (10% of body weight), we retrospectively studied 58 SCLC parafin sections of transbronchial biopsy specimens immunostained using monoclonal antibody against N-terminus of the human p53 protein and monoclonal antibody against Bcl-2 oncoprotein. p53 and Bcl-2 expression were observed in 41% and 57% of patients, respectively. p53 and Bcl-2 expression were not correlated with disease-free survival. There was also no correlation of p53 and Bcl-2 expression with age, sex, weight loss, and performance status. There was a significant correlation of p53 (P < 0.001) and Bcl-2 (P < 0.045) expressions with limited-stage disease.