p53 and cancer therapy: a double-edged sword

Network pharmacology study to explore the multiple molecular mechanism of SH003 in the treatment of non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is one of the leading causes of human death worldwide. Herbal prescription SH003 has been developed to treat several cancers including NSCLC. Due to the multi-component nature of SH003 with multiple targets and pathways, a network pharmacology study was conducted to analyze its active compounds, potential targets, and pathways for the treatment of NSCLC.

METHODS

We systematically identified oral active compounds within SH003, employing ADME criteria-based screening from TM-MC, OASIS, and TCMSP databases. Concurrently, SH003-related and NSCLC-associated targets were amalgamated from various databases. Overlapping targets were deemed anti-NSCLC entities of SH003. Protein-protein interaction networks were constructed using the STRING database, allowing the identification of pivotal proteins through node centrality measures. Empirical validation was pursued through LC-MS analysis of active compounds. Additionally, in vitro experiments, such as MTT cell viability assays and western blot analyses, were conducted to corroborate network pharmacology findings.

RESULTS

We discerned 20 oral active compounds within SH003 and identified 239 core targets shared between SH003 and NSCLC-related genes. Network analyses spotlighted 79 hub genes, including TP53, JUN, AKT1, STAT3, and MAPK3, crucial in NSCLC treatment. GO and KEGG analyses underscored SH003's multifaceted anti-NSCLC effects from a genetic perspective. Experimental validations verified SH003's impact on NSCLC cell viability and the downregulation of hub genes. LC-MS analysis confirmed the presence of four active compounds, namely hispidulin, luteolin, baicalein, and chrysoeriol, among the eight compounds with a median of > 10 degrees in the herb-compounds-targets network in SH003. Previously unidentified targets like CASP9, MAPK9, and MCL1 were unveiled, supported by existing NSCLC literature, enhancing the pivotal role of empirical validation in network pharmacology.

CONCLUSION

Our study pioneers the harmonization of theoretical predictions with practical validations. Empirical validation illuminates specific SH003 compounds within NSCLC, simultaneously uncovering novel targets for NSCLC treatment. This integrated strategy, accentuating empirical validation, establishes a paradigm for in-depth herbal medicine exploration. Furthermore, our network pharmacology study unveils fresh insights into SH003's multifaceted molecular mechanisms combating NSCLC. Through this approach, we delineate active compounds of SH003 and target pathways, reshaping our understanding of its therapeutic mechanisms in NSCLC treatment.

[High expression of secretogranin II increases oxaliplatin resistance of colorectal cancer cells]

OBJECTIVE

To investigate the expression of secretogranin II (SCG2) in colorectal cancer (CRC) tissues and its impact on oxaliplatin resistance of CRC cells.

METHODS

We performed immunohistochemistry to detect the expression level of SCG2 on a tissue microarray containing 96 CRC and 84 adjacent tissues and analyzed the association of SCG2 expression with the clinical features of the CRC patients. SCG2 expression was also measured in DLD1 cells treated with oxaliplatin using immunoblotting and RT-qPCR analyses. The effects of SCG2 expression on oxaliplatin sensitivity and cell viability were evaluated in a DLD1 cell model of SCG2 knockout established using CRISPR-cas9 technique, and the expressions of apoptosis-related proteins were detected using Western blotting and RT-qPCR. We further examined SCG2 expression levels in an oxaliplatin-resistant DLD1 cell line and its parental DLD1 cells.

RESULTS

SCG2 expression was significantly increased in CRC tissues as compared with the adjacent tissues (1.932±0.816 vs 1), and the tumor tissues in advanced stages showed higher SCG2 expression levels. In DLD1 cells, treatment with oxaliplatin significantly increased SCG2 expression, and SCG2 knockout obviously increased oxaliplatin sensitivity of the cells and enhanced the expressions of apoptosis-related proteins. Compared with the parental cells, oxaliplatin-resistant DLD1 cells showed a significant increase of SCG2 expression by 3.901±0.471 folds.

CONCLUSION

SCG2 may serve as a risk gene in CRC, and its high expression increases oxaliplatin resistance of CRC cells.

DRAM1 increases the secretion of PKM2-enriched EVs from hepatocytes to promote macrophage activation and disease progression in ALD

DNA damage-regulated autophagy modulator 1 (DRAM1) could play important roles in inflammation and hepatic apoptosis, while its roles in alcohol-related liver disease (ALD), which is characterized by hepatic inflammation and apoptosis, are still unclear. In this study, we explored the expression, role, and mechanism of DRAM1 in ALD. Firstly, our results showed that DRAM1 was significantly increased in liver tissues of mice at the early stage of alcohol treatment. In addition, DRAM1 knockout reduced, and liver-specific overexpression of DRAM1 aggravated, alcohol-induced hepatic steatosis, injury, and expressions of M1 macrophage markers in mice. Furthermore, ethanol-induced DRAM1 of hepatic cells increased pyruvate kinase M2 (PKM2)-enriched extracellular vesicles (EVs), and ectosomes derived from hepatic cells with DRAM1 overexpression promoted macrophage activation. Mechanistic investigations showed that DRAM1 interacted with PKM2 and increased the PKM2 level in plasma membrane. At last, DRAM1 was significantly increased in liver tissues of ALD patients, and it was positively correlated with M1 macrophage markers. Taken together, this study revealed that ethanol-induced DRAM1 of hepatic cells could increase the PKM2-enriched EVs, promote macrophage activation, and aggravate the disease progression of ALD. These findings suggested that DRAM1 might be a potentially promising target for the therapy of ALD.

Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

Breast cancer (BC) is the second cause of cancer-related deceases in the worldwide female population. Despite the successful treatment advances, 25% of BC develops resistance to current therapeutic regimens, thereby remaining a major hurdle for patient management. Current therapies, targeting the molecular events underpinning the adaptive resistance, still require effort to improve BC treatment. Using BC sphere cells (BCSphCs) as a model, here we showed that BC stem-like cells express high levels of Myc, which requires the presence of the multifunctional DNA/RNA binding protein Sam68 for the DNA-damage repair. Analysis of a cohort of BC patients displayed that Sam68 is an independent negative factor correlated with the progression of the disease. Genetic inhibition of Sam68 caused a defect in PARP-induced PAR chain synthesis upon DNA-damaging insults, resulting in cell death of TNBC cells. In contrast, BC stem-like cells were able to survive due to an upregulation of Rad51. Importantly, the inhibition of Rad51 showed synthetic lethal effect with the silencing of Sam68, hampering the cell viability of patient-derived BCSphCs and stabilizing the growth of tumor xenografts, including those TNBC carrying BRCA mutation. Moreover, the analysis of Myc, Sam68 and Rad51 expression demarcated a signature of a poor outcome in a large cohort of BC patients. Thus, our findings suggest the importance of targeting Sam68-PARP1 axis and Rad51 as potential therapeutic candidates to counteract the expansion of BC cells with an aggressive phenotype.

Assessing alveolar rhabdomyosarcoma cell lines as tumor models by comparison of mRNA expression profiles

Numerous cell lines for human alveolar rhabdomyosarcoma (ARMS) have been developed and are widely used to study biological processes of this myogenic cancer. The present study investigated the resemblance of commonly used ARMS cell lines to primary tumors in regards to gene expression. RNA-sequencing data was retrieved from published datasets for 4 commonly used ARMS cell lines and 35 ARMS primary tumors. The genes with most variable expression across primary tumors were used to calculate rank-based Spearman's correlation. The observed median correlations ranged from 0.36 to 0.61. RH-41 showed the highest median correlation while KYM-1 was the least correlated cell line. A significant number of genes dysregulated between tumors and non-tumors also exhibited similar expression patterns between tumors and cell lines, including The findings suggest that ARMS cell lines exhibit changes in gene expression compared to primary tumors and may not be completely representative of the disease process.

Ruthenium-Containing Linear Helicates and Mesocates with Tuneable p53-Selective Cytotoxicity in Colorectal Cancer Cells

The ligands L¹ and L² both form separable dinuclear double-stranded helicate and mesocate complexes with Ru^II . In contrast to clinically approved platinates, the helicate isomer of [Ru₂ (L¹ )₂ ]⁴⁺ was preferentially cytotoxic to isogenic cells (HCT116 p53^-/- ), which lack the critical tumour suppressor gene. The mesocate isomer shows the reverse selectivity, with the achiral isomer being preferentially cytotoxic towards HCT116 p53^+/+ . Other structurally similar Ru^II -containing dinuclear complexes showed very little cytotoxic activity. This study demonstrates that alterations in ligand or isomer can have profound effects on cytotoxicity towards cancer cells of different p53 status and suggests that selectivity can be "tuned" to either genotype. In the search for compounds that can target difficult-to-treat tumours that lack the p53 tumour suppressor gene, [Ru₂ (L¹ )₂ ]⁴⁺ is a promising compound for further development.

Magnetite nanoparticles inhibit tumor growth and upregulate the expression of p53/p16 in Ehrlich solid carcinoma bearing mice

Background

Magnetite nanoparticles (MNPs) have been widely used as contrast agents and have promising approaches in cancer treatment. In the present study we used Ehrlich solid carcinoma (ESC) bearing mice as a model to investigate MNPs antitumor activity, their effect on expression of p53 and p16 genes as an indicator for apoptotic induction in tumor tissues.

Method

MNPs coated with ascorbic acid (size: 25.0±5.0 nm) were synthesized by co-precipitation method and characterized. Ehrlich mice model were treated with MNPs using 60 mg/Kg day by day for 14 injections; intratumorally (IT) or intraperitoneally (IP). Tumor size, pathological changes and iron content in tumor and normal muscle tissues were assessed. We also assessed changes in expression levels of p53 and p16 genes in addition to p53 protein level by immunohistochemistry.

Results

Our results revealed that tumor growth was significantly reduced by IT and IP MNPs injection compared to untreated tumor. A significant increase in p53 and p16 mRNA expression was detected in Ehrlich solid tumors of IT and IP treated groups compared to untreated Ehrlich solid tumor. This increase was accompanied with increase in p53 protein expression. It is worth mentioning that no significant difference in expression of p53 and p16 could be detected between IT ESC and control group.

Conclusion

MNPs might be more effective in breast cancer treatment if injected intratumorally to be directed to the tumor tissues.

Notch3 inhibition enhances sorafenib cytotoxic efficacy by promoting GSK3b phosphorylation and p21 down-regulation in hepatocellular carcinoma

Sorafenib (Nexavar), a multiple kinase inhibitor, is the only clinically approved drug for patients with advanced HCC. However, its therapeutic success is limited by the emergence of drug resistance. Here we found that p21 and pGSK3β^Ser9 are major players in the resistance to sorafenib. We recently reported that aberrant Notch3 expression in HCC contributes to doxorubicin resistance in vitro and, therefore, we focused on the mechanisms that associate Notch3 to acquired drug resistance. In this study we first found that Notch3 inhibition significantly increased the apoptosis inducing effect of sorafenib in HCC cells via specific down-regulation of p21 and up-regulation of pGSK3β^Ser9. Using a mouse xenograft model we further found that Notch3 depletion combined with 21 days of sorafenib treatment exerts a substantial antitumor effect in vivo. Interestingly, we showed that, upon exposure to sorafenib treatment, Notch3 depleted xenografts maintain lower levels of p21 and higher levels of pGSK3β^Ser9 than control xenografts. Thus, this study demonstrated that inhibition of Notch3 signaling prevents HCC-mediate drug resistance and sensitizes HCC cells to sorafenib. Finally, we validated our in vitro and in vivo results in primary human HCCs showing that Notch3 protein expression positively correlated with p21 protein expression and negatively correlated with pGSK3β^Ser9 expression. In conclusion, the results presented in this study demonstrated that Notch3 silencing enhances the effect of sorafenib by overcoming drug resistance. Notch3 inhibition in combination with sorafenib can be a promising strategy for treatment of HCC.

NRF2 and p53: Januses in cancer?

The transcription factor nuclear factor (erythroid-derived 2)-like 2, also known as NFE2L2 or NRF2, is a master regulator of the anti-oxidative stress response and positively controls the expression of a battery of anti-oxidative stress response proteins and enzymes implicated in detoxification and glutathione generation. Although its detoxifying activity is important in cancer prevention, it has recently been shown that cancer cells also exploit its protective functions to thrive and resist chemotherapy. NRF2 was also shown to the pentose phosphate pathway and glutaminolysis, which promotes purine synthesis for supporting rapid proliferation and glutathione for providing anti-oxidative stress protection. Evidence obtained from cancer patients and cell lines suggest that NRF2 is highly active in a variety of human cancers and is associated with aggressiveness. p53 is a tumor suppressor that also promotes an anti-oxidative stress metabolic program and glutaminolysis. Here we will discuss the similarities between NRF2 and p53 and review evidence that p53 might be exploited by cancer cells to gain protection against oxidative stress, as is the case for NRF2. We discuss findings of co-regulation between these transcription factors and propose possible therapeutic strategies that can be used for treatment of cancers that harbor WT p53 and express high levels of NRF2.

Inhibition of p53 expression by peptide-conjugated phosphorodiamidate morpholino oligomers sensitizes human cancer cells to chemotherapeutic drugs

The p53 tumor suppressor gene encodes a transcription factor that is commonly mutated in cancer. Tumors arise when premalignant cells are unable to undergo p53-dependent apoptosis, cell cycle arrest or DNA repair. The p53-signaling pathway affects not only tumor development, but also the response of tumors to chemotherapeutic drugs. In this study, we use cell penetrating peptide conjugates of phosphorodiamidate morpholino oligomers (PPMOs) to inhibit p53 expression. We examine the functional properties of endogenous p53 isoforms that are produced upon PPMO-mediated inhibition of p53 translation and splicing, and report that loss of N-terminal or C-terminal sequences interferes with the transcriptional activity of p53. Importantly, we report that PPMO-mediated inhibition of p53 expression sensitizes human cancer cells with wild-type p53 to chemotherapeutic drugs.

Zeranol down-regulates p53 expression in primary cultured human breast cancer epithelial cells through epigenetic modification

Epidemiological studies have suggested that there are many risk factors associated with breast cancer. Silencing tumor suppressor genes through epigenetic alterations play critical roles in breast cancer initiation, promotion and progression. As a growth promoter, Zeranol (Z) has been approved by the FDA and is widely used to enhance the growth of beef cattle in the United States. However, the safety of Z use as a growth promoter is still under debate. In order to provide more evidence to clarify this critical health issue, the current study investigated the effect of Z on the proliferation of primary cultured human normal and cancerous breast epithelial cells (PCHNBECs and PCHBCECs, respectively) isolated from the same patient using MTS assay, RT-PCR and Western blot analysis. We also conducted an investigation regarding the mechanisms that might be involved. Our results show that Z is more potent to stimulate PCHBCEC growth than PCHNBEC growth. The stimulatory effects of Z on PCHBCECs and PCHBCECs may be mediated by its down-regulating expression of the tumor suppressor gene p53 at the mRNA and protein levels. Further investigation showed that the expression of DNA methylatransferase 1 mRNA and protein levels is up-regulated by treatment with Z in PCHBCECs as compared to PCHNBECs, which suggests a role of Z in epigenetic modification involved in the regulation of p53 gene expression in PCHBCECs. Our experimental results imply the potentially adverse health effect of Z in breast cancer development. Further study is continuing in our laboratory.

Exquisite sensitivity of TP53 mutant and basal breast cancers to a dose-dense epirubicin-cyclophosphamide regimen

BACKGROUND

In breast cancers, only a minority of patients fully benefit from the different chemotherapy regimens currently in use. Identification of markers that could predict the response to a particular regimen would thus be critically important for patient care. In cell lines or animal models, tumor protein p53 (TP53) plays a critical role in modulating the response to genotoxic drugs. TP53 is activated in response to DNA damage and triggers either apoptosis or cell-cycle arrest, which have opposite effects on cell fate. Yet, studies linking TP53 status and chemotherapy response have so far failed to unambiguously establish this paradigm in patients. Breast cancers with a TP53 mutation were repeatedly shown to have a poor outcome, but whether this reflects poor response to treatment or greater intrinsic aggressiveness of the tumor is unknown.

METHODS AND FINDINGS

In this study we analyzed 80 noninflammatory breast cancers treated by frontline (neoadjuvant) chemotherapy. Tumor diagnoses were performed on pretreatment biopsies, and the patients then received six cycles of a dose-dense regimen of 75 mg/m(2) epirubicin and 1,200 mg/m(2) cyclophosphamide, given every 14 days. After completion of chemotherapy, all patients underwent mastectomies, thus allowing for a reliable assessment of chemotherapy response. The pretreatment biopsy samples were used to determine the TP53 status through a highly efficient yeast functional assay and to perform RNA profiling. All 15 complete responses occurred among the 28 TP53-mutant tumors. Furthermore, among the TP53-mutant tumors, nine out of ten of the highly aggressive basal subtypes (defined by basal cytokeratin [KRT] immunohistochemical staining) experienced complete pathological responses, and only TP53 status and basal subtype were independent predictors of a complete response. Expression analysis identified many mutant TP53-associated genes, including CDC20, TTK, CDKN2A, and the stem cell gene PROM1, but failed to identify a transcriptional profile associated with complete responses among TP53 mutant tumors. In patients with unresponsive tumors, mutant TP53 status predicted significantly shorter overall survival. The 15 patients with responsive TP53-mutant tumors, however, had a favorable outcome, suggesting that this chemotherapy regimen can overcome the poor prognosis generally associated with mutant TP53 status.

CONCLUSIONS

This study demonstrates that, in noninflammatory breast cancers, TP53 status is a key predictive factor for response to this dose-dense epirubicin-cyclophosphamide regimen and further suggests that the basal subtype is exquisitely sensitive to this association. Given the well-established predictive value of complete responses for long-term survival and the poor prognosis of basal and TP53-mutant tumors treated with other regimens, this chemotherapy could be particularly suited for breast cancer patients with a mutant TP53, particularly those with basal features.

Neoadjuvant radiochemotherapy of oral cavity and oropharyngeal cancer: evaluation of tumor response by CT differs from histopathologic response assessment in a significant fraction of patients

BACKGROUND

Our aim was to compare and assess the predictive value of CT and histopathologic grading of tumor regression at primary tumor sites in patients with squamous cell carcinoma of the oral cavity and oropharynx after neoadjuvant (preoperative) radiochemotherapy (RCT).

METHODS

We investigated 55 patients with carcinomas of the oral cavity and oropharynx who underwent RCT before curative surgery. Two blinded observers measured RCT-induced reduction of tumor volume in pretherapeutic and posttherapeutic CT scans. Volume changes were compared with histopathologic findings obtained at surgery.

RESULTS

Histopathologic response evaluation revealed 31 complete remissions, 12 cases of partial response, and 12 nonresponders. We performed a logistic regression analysis to evaluate whether measured volume reduction could predict the likelihood of belonging to a certain response group. Taken together, we found 35 correct, 12 false-negative, and seven false-positive predictions.

CONCLUSIONS

The extent of remission as assessed by CT scans 4 to 5 weeks after completion of neoadjuvant RCT leads to false predictions in a significant percentage of patients.

Depletion of Endogenous Nitric Oxide Enhances Cisplatin-induced Apoptosis in a p53-dependent Manner in Melanoma Cell Lines

The expression of inducible nitric-oxide synthase in melanoma tumor cells was recently shown to correlate strongly with poor patient survival after combination biochemotherapy (p<0.001). Furthermore, evidence suggests that nitric oxide, a reaction product of nitric oxide synthase, exhibits antiapoptotic activity in melanoma cells. We therefore hypothesized that nitric oxide antagonizes chemotherapy-induced apoptosis. Whether nitric oxide is capable of regulating cell growth and apoptotic responses to cisplatin treatment in melanoma cell lines was evaluated. We demonstrate herein that depletion of endogenously produced nitric oxide can inhibit melanoma proliferation and promote apoptosis. Moreover, our data indicate that the depletion of nitric oxide leads to changes in cell cycle regulation and enhances cisplatin-induced apoptosis in melanoma cells. Strikingly, we observed that the depletion of nitric oxide inhibits cisplatin-induced wild type p53 accumulation and p21(Waf1/Cip1/Sdi1) expression in melanoma cells. When cisplatin-induced p53 binding to the p21(Waf1/Cip1/Sdi1) promoter was examined, it was found that nitric oxide depletion significantly reduced the presence of p53-DNA complexes after cisplatin treatment. Furthermore, dominant negative inhibition of p53 activity enhanced cisplatin-induced apoptosis. Together, these data strongly suggest that endogenously produced nitric oxide is required for cisplatin-induced p53 activation and p21(Waf1/Cip1/Sdi1) expression, which can regulate melanoma sensitivity to cisplatin.

Increased sensitivity of p53-deficient cells to anticancer agents due to loss of Pms2

A large fraction of human tumours carries mutations in the p53 gene. p53 plays a central role in controlling cell cycle checkpoint regulation, DNA repair, transcription, and apoptosis upon genotoxic stress. Lack of p53 function impairs these cellular processes, and this may be the basis of resistance to chemotherapeutic regimens. By virtue of the involvement of DNA mismatch repair in modulating cytotoxic pathways in response to DNA damaging agents, we investigated the effects of loss of Pms2 on the sensitivity to a panel of widely used anticancer agents in E1A/Ha-Ras-transformed p53-null mouse fibroblasts either proficient or deficient in Pms2. We report that lack of the Pms2 gene is associated with an increased sensitivity, ranging from 2-6-fold, to some types of anticancer agents including the topoisomerase II poisons doxorubicin, etoposide and mitoxantrone, the platinum compounds cisplatin and oxaliplatin, the taxanes docetaxel and paclitaxel, and the antimetabolite gemcitabine. In contrast, no change in sensitivity was found after treatment with 5-fluorouracil. Cell cycle analysis revealed that both, Pms2-deficient and -proficient cells, retain the ability to arrest at the G2/M upon cisplatin treatment. The data indicate that the concomitant loss of Pms2 function chemosensitises p53-deficient cells to some types of anticancer agents, that Pms2 positively modulates cell survival by mechanisms independent of p53, and that increased cytotoxicity is paralleled by increased apoptosis. Tumour-targeted functional inhibition of Pms2 may be a valuable strategy for increasing the efficacy of anticancer agents in the treatment of p53-mutant cancers.

Effect of mutated TP53 on response of advanced breast cancers to high-dose chemotherapy

TP53 activation by genotoxic drugs can induce apoptosis or cell-cycle arrest. Thus, whether the gene is mutated or wild type could affect the response of a tumour to chemotherapy. Clinical data are unclear, possibly as a result of heterogeneity of tumours, drugs, methods of assessing response, or TP53 status. We studied 50 non-inflammatory, locally advanced breast cancers that had been treated with high doses of a combination of epirubicin and cyclophosphamide. We noted eight complete responses, which all occurred in the 14 patients with tumours containing mutated TP53 (p<0.0001). In high-grade, advanced breast cancers, inactivation of the TP53 pathway could greatly improve the response to this chemotherapy regimen.

Acid sphingomyelinase activation requires caspase-8 but not p53 nor reactive oxygen species during Fas-induced apoptosis in human glioma cells

During apoptosis of human glioma cells induced by anti-Fas antibody, ceramide formation with activation of acid, but not neutral sphingomyelinase (SMase), was observed. A potent inhibitor of acid SMase, SR33557, effectively inhibited ceramide formation and apoptosis. Fas-induced apoptosis and ceramide formation proceeded regardless of p53 status. The agents, which modify intracellular levels of reactive oxygen species (ROS) and reduced glutathione (GSH), failed to modulate Fas-induced acid SMase activation and apoptosis. Moreover, expression of functional p53 protein using a temperature-sensitive human p53val(138) induced ceramide generation by activation of neutral SMase but not acid SMase through ROS formation. Peptide inhibitors for caspases-8 (z-IETD-fmk) and -3 (z-DEVD-fmk) suppressed Fas-induced apoptosis. However, activation of acid SMase was inhibited only by z-IETD-fmk. Thus, ceramide generated by acid SMase may take a part in Fas-induced apoptosis of human glioma cells and acid SMase activation may be dependent on caspase-8 activation, but not on p53 nor ROS.

Cytokine production by macrophages in association with phagocytosis of etoposide-treated P388 cells in vitro and in vivo

Chemotherapy and radiotherapy are performed for cancer patients with the hope that dying cancer cells are safely scavenged by phagocytic cells such as macrophages. In this study, we examined cytokine production by macrophages during and after the phagocytosis of etoposide-treated P388 cells in vitro and in vivo. Etoposide caused apoptosis as early as 5 h after treatment, as assessed as to the exposure of phosphatidylserine, increase in membrane permeability and DNA ladder formation. Phagocytosis by phorbol myristate acetate (PMA)-treated THP-1 cells occurred marginally when P388 cells were treated with etoposide for 10 h, while it occurred significantly with P388 cells treated for 24 h, as evidenced by flow cytometry and confocal microscopy. PMA-treated THP-1 cells produced pro-inflammatory cytokines, such as interleukin (IL)-1alpha, IL-8 and macrophage migration inhibitory factor (MIF), but not anti-inflammatory cytokines among those tested at the mRNA level during and after the phagocytosis of apoptotic cells. IL-8 and MIF were also produced at the protein level, and the IL-8 production was dependent on cell-to-cell contact when the plasma membranes of apoptotic cells were intact enough not to leak one of the cytoplasmic enzymes, lactate dehydrogenase. In addition, etoposide-treated P388 cells induced neutrophil infiltration as well as MIP-2 production upon injection into the peritoneal cavity of either normal mice or mice with sterile peritonitis. When macrophages ingesting and/or binding apoptotic P388 cells were isolated from the mice with sterile peritonitis using a cell sorter, they were found to produce MIP-2 upon culture.

Pathways of apoptosis and the modulation of cell death in cancer

Although cell death once was viewed exclusively as the disordered, chaotic outcome of metabolic catastrophe, apoptosis now is recognized as a highly ordered, evolutionarily conserved, and genetically selected program that is essential for normal development. The death receptor pathway of apoptosis, cytotoxic T cells, prolife survival signals, Bcl-2 family of regulators, p53 and regulated cell death in cancer, and oncogenes are reviewed. Future prospects in this arena also are discussed.

Genetic Stabilization by p53 Involves Growth Regulatory and Repair Pathways

p53 performs a plethora of activities, which are directed towards the maintenance of the genomic integrity and constitute its universal role as a tumor suppressor. 1000 to 10000 latent p53 molecules are permanently available in order to monitor DNA exchange processes in mitotically growing cells. After the introduction of major DNA injuries the levels of posttranslationally modified p53 proteins rise, which in turn transcriptionally signal transient cell cycle arrest or apoptotic cell death, depending on the extent of damage. Taken together, p53 inhibits the manifestation of genomic instabilities at different control levels both during naturally occurring metabolic processes and in response to genotoxic treatments.

Tp53 gene therapy: a key to modulating resistance to anticancer therapies?

Abnormalities in the p53 tumor suppressor have been identified in over 60% of human cancers. The status of p53 within tumor cells has been proposed to be one of the major determinants of the response to anticancer therapies. In this review we examine the relationship between functional p53 and sensitivity, or resistance, to chemotherapy and radiotherapy. We also discuss the potential of current gene-therapy approaches to restore functional p53 to tumors as a means of modulating the effects of radiation and chemotherapy.

Evaluation of the predictive value of Her-2/neu overexpression and p53 mutations in high-risk primary breast cancer patients treated with high-dose chemotherapy and autologous stem-cell transplantation

PURPOSE

To ascertain the predictive value of Her-2/neu overexpression and p53 mutations, assessed by immunohistochemistry, in high-risk primary breast cancer (HRPBC) treated with high-dose chemotherapy (HDCT).

PATIENTS AND METHODS

We obtained paraffin-embedded tumor blocks from 146 HRPBC patients previously enrolled at our program onto clinical trials of HDCT for four to nine involved axillary lymph nodes, > or = 10 involved axillary nodes, or inflammatory carcinoma. All patients received the same HDCT regimen, with cyclophosphamide, cisplatin, and carmustine (STAMP-I), followed by autologous stem-cell transplantation. Median follow-up was 42 months (range, 5 to 90 months). The same pathologist, blinded to clinical outcome, reviewed all immunostained slides.

RESULTS

Positive results for Her-2/neu and p53 were found in 44.5% and 34% of the patients, respectively. Positivity for Her-2/neu was significantly associated with increased risk of relapse and death. No correlation was found between p53 mutations and relapse-free survival (RFS) or overall survival (OS). Multivariate analyses included Her-2/neu overexpression and the following variables previously identified as independent predictors of outcome in this population: tumor size, nodal ratio (number of involved nodes/number of dissected nodes), and hormone receptor status. All four variables had independent value.

CONCLUSION

Her-2/neu overexpression is an independent negative predictor of RFS and OS in HRPBC treated with HDCT. Its inclusion in our previously described predictive model increases the predictive capacity of this model for the low-risk subgroup. In contrast, p53 mutations lack predictive value in this setting.