The relationship between cisplatin-induced apoptosis and p53, bcl-2 and bax expression in human lung cancer cells

Metal-Based Anticancer Complexes and p53: How Much Do We Know?

P53 plays a key role in protecting the human genome from DNA-related mutations; however, it is one of the most frequently mutated genes in cancer. The P53 family members p63 and p73 were also shown to play important roles in cancer development and progression. Currently, there are various organic molecules from different structural classes of compounds that could reactivate the function of wild-type p53, degrade or inhibit mutant p53, etc. It was shown that: (1) the function of the wild-type p53 protein was dependent on the presence of Zn atoms, and (2) Zn supplementation restored the altered conformation of the mutant p53 protein. This prompted us to question whether the dependence of p53 on Zn and other metals might be used as a cancer vulnerability. This review article focuses on the role of different metals in the structure and function of p53, as well as discusses the effects of metal complexes based on Zn, Cu, Fe, Ru, Au, Ag, Pd, Pt, Ir, V, Mo, Bi and Sn on the p53 protein and p53-associated signaling.

Roles of non-coding RNAs in cell death pathways involved in the treatment of resistance and recurrence of cancer

Considering the burden of cancer, a number of methods have been applied to control or stop it. However, because of drug resistance or cancer recurrence, these treatments usually face failure. Combination of modulation of expression of non-coding RNAs (ncRNAs) with other treatments can increase treatment-sensitivity of tumors but these approaches still face some challenges. Gathering information in this field is a prerequisite to find more efficient cures for cancer. Cancer cells use ncRNAs to enhance uncontrolled proliferation originated from inactivation of cell death routs. In this review article, the main routes of cell death and involved ncRNAs in these routes are discussed. Moreover, extant information in the role of different ncRNAs on cell death pathways involved in the treatment resistance and cancer recurrence is summarized.

Phosphorylation of IGFBP-3 by Casein Kinase 2 Blocks Its Interaction with Hyaluronan, Enabling HA-CD44 Signaling Leading to Increased NSCLC Cell Survival and Cisplatin Resistance

Cisplatin is a platinum agent used in the treatment of non-small cell lung cancer (NSCLC). Much remains unknown regarding the basic operative mechanisms underlying cisplatin resistance in NSCLC. In this study, we found that phosphorylation of IGFBP-3 by CK2 (P-IGFBP-3) decreased its binding to hyaluronan (HA) but not to IGF-1 and rendered the protein less effective at reducing cell viability or increasing apoptosis than the non-phosphorylated protein with or without cisplatin in the human NSCLC cell lines, A549 and H1299. Our data suggest that blocking CD44 signaling augmented the effects of cisplatin and that IGFBP-3 was more effective at inhibiting HA-CD44 signaling than P-IGFBP-3. Blocking CK2 activity and HA-CD44 signaling increased cisplatin sensitivity and more effectively blocked the PI3K and AKT activities and the phospho/total NFκB ratio and led to increased p53 activation in A549 cells. Increased cell sensitivity to cisplatin was observed upon co-treatment with inhibitors targeted against PI3K, AKT, and NFκB while blocking p53 activity decreased A549 cell sensitivity to cisplatin. Our findings shed light on a novel mechanism employed by CK2 in phosphorylating IGFBP-3 and increasing cisplatin resistance in NSCLC. Blocking phosphorylation of IGFBP-3 by CK2 may be an effective strategy to increase NSCLC sensitivity to cisplatin.

Melatonin Increases the Sensitivity of Osteosarcoma Cells to Chemotherapy Drug Cisplatin

Chemotherapy, which is one of the common treatments for osteosarcoma (OS), has many side effects and in some cases has low effectiveness due to chemoresistance, hence it is vital to study new therapies for OS. In this regard, we combined melatonin with cisplatin and evaluate their effect on MG63 OS cells. Since melatonin has anti-cancer properties, we hypothesized that its combination with cisplatin could increase the effectiveness of cisplatin. Firstly, MTT assay was used to evaluate the cell viability and cytotoxicity of cisplatin on MG63 cells and the results showed that melatonin in combination with cisplatin increases the sensitivity of MG63 cells to cisplatin. In addition, qRT-PCR results showed that the expressions of miR-181 and P53, CYLD, CBX7 and BCL2 genes change in MG63 cells after treatment with the combination of cisplatin and melatonin, so that the expression of P53, CYLD and CBX7 increased and the expression of BCL2 and miR-181b decreases significantly. Furthermore, analysis of Annexin V/FITC assay data revealed that the rate of apoptosis in MG63 OS cell line remarkably promoted after treated with cisplatin and melatonin combination. As a result, our findings show that melatonin in combination with cisplatin increases the effectiveness of cisplatin in osteosarcoma cells and this study provides a new therapeutic approach for OS.

Bax/Bcl-2 Cascade Is Regulated by the EGFR Pathway: Therapeutic Targeting of Non-Small Cell Lung Cancer

Non-small cell lung carcinoma (NSCLC) comprises 80%-85% of lung cancer cases. EGFR is involved in several cancer developments, including NSCLC. The EGFR pathway regulates the Bax/Bcl-2 cascade in NSCLC. Increasing understanding of the molecular mechanisms of fundamental tumor progression has guided the development of numerous antitumor drugs. The development and improvement of rationally planned inhibitors and agents targeting particular cellular and biological pathways in cancer have been signified as a most important paradigm shift in the strategy to treat and manage lung cancer. Newer approaches and novel chemotherapeutic agents are required to accompany present cancer therapies for improving efficiency. Using natural products as a drug with an effective delivery system may benefit therapeutics. Naturally originated compounds such as phytochemicals provide crucial sources for novel agents/drugs and resources for tumor therapy. Applying the small-molecule inhibitors (SMIs)/phytochemicals has led to potent preclinical discoveries in various human tumor preclinical models, including lung cancer. In this review, we summarize recent information on the molecular mechanisms of the Bax/Bcl-2 cascade and EGFR pathway in NSCLC and target them for therapeutic implications. We further described the therapeutic potential of Bax/Bcl-2/EGFR SMIs, mainly those with more potent and selectivity, including gefitinib, EGCG, ABT-737, thymoquinone, quercetin, and venetoclax. In addition, we explained the targeting EGFR pathway and ongoing in vitro and in vivo and clinical investigations in NSCLC. Exploration of such inhibitors facilitates the future treatment and management of NSCLC.

Iminodibenzyl redirected cyclooxygenase-2 catalyzed dihomo-γ-linolenic acid peroxidation pattern in lung cancer

Cyclooxygenase-2 (COX-2) is up-regulated by redox imbalance and is considered a target for cancer therapy. The rationale of the COX-2 inhibitor lies in suppressing COX-2 catalyzed peroxidation of omega-6 polyunsaturated fatty acids (PUFAs), which are essential and pervasive in our daily diet. However, COX-2 inhibitors fail to improve cancer patients' survival and may lead to severe side effects. Here, instead of directly inhibiting COX-2, we utilize a small molecule, iminodibenzyl, which could reprogram the COX-2 catalyzed omega-6 PUFAs peroxidation in lung cancer by inhibiting delta-5-desaturase (D5D) activity. Iminodibenzyl breaks the conversion from dihomo-γ-linolenic acid (DGLA) to arachidonic acid, resulting in the formation of a distinct byproduct, 8-hydroxyoctanoic acid, in lung cancer cells and solid tumors. By utilizing COX-2 overexpression in cancer, the combination of DGLA supplementation and iminodibenzyl suppressed YAP1/TAZ pathway, decreasing the tumor size and lung metastasis in nude mice and C57BL/6 mice. This D5D inhibition-based strategy selectively damaged lung cancer cells with a high COX-2 level, whereas it could avoid harassing normal lung epithelial cells. This finding challenged the COX-2 redox basis in cancer, providing a new direction for developing omega-6 (DGLA)-based diet/regimen in lung cancer therapy.

A Potential Role for HUWE1 in Modulating Cisplatin Sensitivity

Cisplatin is a widely used antineoplastic agent, whose efficacy is limited by primary and acquired therapeutic resistance. Recently, a bladder cancer genome-wide CRISPR/Cas9 knock-out screen correlated cisplatin sensitivity to multiple genetic biomarkers. Among the screen’s top hits was the HECT domain-containing ubiquitin E3 ligase (HUWE1). In this review, HUWE1 is postulated as a therapeutic response modulator, affecting the collision between platinum-DNA adducts and the replication fork, the primary cytotoxic action of platins. HUWE1 can alter the cytotoxic response to platins by targeting essential components of the DNA damage response including BRCA1, p53, and Mcl-1. Deficiency of HUWE1 could lead to enhanced DNA damage repair and a dysfunctional apoptotic apparatus, thereby inducing resistance to platins. Future research on the relationship between HUWE1 and platins could generate new mechanistic insights into therapy resistance. Ultimately, HUWE1 might serve as a clinical biomarker to tailor cancer treatment strategies, thereby improving cancer care and patient outcomes.

Chemosensitizing activity of peptide from Lentinus squarrosulus (Mont.) on cisplatin-induced apoptosis in human lung cancer cells

The limitations of cisplatin, a standard chemotherapy for lung cancer, have been documented with serious adverse effects and drug resistance. To address the need for novel therapy, this study firstly reveals the potential of peptide from Lentinus squarrosulus (Mont.) as a chemotherapeutic adjuvant for cisplatin treatment. The purified peptide from L. squarrosulus aqueous extracts was obtained after eluting with 0.4 M NaCl through FPLC equipped with anion exchange column. Preincubation for 24 h with 5 µg/mL of the peptide at prior to treatment with 5 µM cisplatin significantly diminished %cell viability in various human lung cancer cells but not in human dermal papilla and proximal renal cells. Flow cytometry indicated the augmentation of cisplatin-induced apoptosis in lung cancer cells pretreated with peptide from L. squarrosulus. Preculture with the peptide dramatically inhibited colony formation in lung cancer cells derived after cisplatin treatment. Strong suppression on integrin-mediated survival was evidenced with the diminution of integrins (β1, β3, β5, α5, αV) and down-stream signals (p-FAK/FAK, p-Src/Src, p-Akt/Akt) consequence with alteration of p53, Bax, Blc-2 and Mcl-1 in cisplatin-treated lung cancer cells preincubated with peptide from L. squarrosulus. These results support the development of L. squarrosulus peptide as a novel combined chemotherapy with cisplatin for lung cancer treatment.

Sensitivity of pancreatic cancer cells to chemotherapeutic drugs, signal transduction inhibitors and nutraceuticals can be regulated by WT-TP53

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic malignancy. Approximately 85% of pancreatic cancers are classified as PDACs. The survival of PDAC patients is very poor and only 5-10% of patients survive 5 years after diagnosis. Mutations at the KRAS and TP53 gene are frequently observed in PDAC patients. The PANC-28 cell line lacks wild-type (WT) TP53. In the following study, we have investigated the effects of restoration of WT TP53 activity on the sensitivity of PANC-28 pancreatic cancer cells to various drugs which are used to treat PDAC patients as well as other cancer patients. In addition, we have examined the effects of signal transduction inhibitors which target critical pathways frequently deregulated in cancer. The effects of the anti-diabetes drug metformin and the anti-malarial drug chloroquine were also examined as these drugs may be repurposed to treat other diseases. Finally, the effects of certain nutraceuticals which are used to treat various ailments were also examined. Introduction of WT-TP53 activity in PANC-28 PDAC cells, can increase their sensitivity to various drugs. Attempts are being made clinically to increase TP53 activity in various cancer types which will often inhibit cell growth by multiple mechanisms.

Ex vivo toxicological evaluation of experimental anticancer gold(i) complexes with lansoprazole-type ligands

Gold-based compounds are of great interest in the field of medicinal chemistry as novel therapeutic (anticancer) agents due to their peculiar reactivity and mechanisms of action with respect to organic drugs. Despite their promising pharmacological properties, the possible toxic effects of gold compounds need to be carefully evaluated in order to optimize their design and applicability. This study reports on the potential toxicity of three experimental gold-based anticancer compounds featuring lansoprazole ligands (1-3) studied in an ex vivo model, using rat precision cut kidney and liver slices (PCKS and PCLS, respectively). The results showed a different toxicity profile for the tested compounds, with the neutral complex 2 being the least toxic, even less toxic than cisplatin, followed by the cationic complex 1. The dinuclear cationic gold complex 3 was the most toxic in both liver and kidney slices. This result correlated with the metal uptake of the different compounds assessed by ICP-MS, where complex 3 showed the highest accumulation of gold in liver and kidney slices. Interestingly compound 1 showed the highest selectivity towards cancer cells compared to the healthy tissues. Histomorphology evaluation showed a similar pattern for all three Au(i) complexes, where the distal tubular cells suffered the most extensive damage, in contrast to the damage in the proximal tubules induced by cisplatin. The binding of representative gold compounds with the model ubiquitin was also studied by ESI-MS, showing that after 24 h incubation only 'naked' Au ions were bound to the protein following ligands' loss. The mRNA expression of stress response genes appeared to be similar for both evaluated organs, suggesting oxidative stress as the possible mechanism of toxicity. The obtained results open new perspectives towards the design and testing of bifunctional gold complexes with chemotherapeutic applications.

A tight balance of Karyopherin β1 expression is required in cervical cancer cells

Background

Karyopherin β1 (Kpnβ1) is the main nuclear import protein involved in the transport of cargoes from the cytoplasm into the cell nucleus. Previous research has found Kpnβ1 to be significantly overexpressed in cervical cancer and other cancer tissues, and further studies showed that inhibition of Kpnβ1 expression by siRNA resulted in cancer cell death, while non-cancer cells were minimally affected. These results suggest that Kpnβ1 has potential as an anticancer therapeutic target, thus warranting further research into the association between Kpnβ1 expression and cancer progression. Here, the biological effects associated with Kpnβ1 overexpression were investigated in order to further elucidate the relationship between Kpnβ1 and the cancer phenotype.

Methods

To evaluate the effect of Kpnβ1 overexpression on cell biology, cell proliferation, cell cycle, cell morphology and cell adhesion assays were performed. To determine whether Kpnβ1 overexpression influences cell sensitivity to chemotherapeutic agents like Cisplatin, cell viability assays were performed. Expression levels of key proteins were analysed by Western blot analysis.

Results

Our data revealed that Kpnβ1 overexpression, above that which was already detected in cancer cells, resulted in reduced proliferation of cervical cancer cells. Likewise, normal epithelial cells showed reduced proliferation after Kpnβ1 overxpression. Reduced cancer cell proliferation was associated with a delay in cell cycle progression, as well as changes in the morphology and adhesion properties of cells. Additionally, Kpnβ1 overexpressing HeLa cells exhibited increased sensitivity to cisplatin, as shown by decreased cell viability and increased apoptosis, where p53 and p21 inhibition reduced and enhanced cell sensitivity to Cisplatin, respectively.

Conclusions

Overall, our results suggest that a tight balance of Kpnβ1 expression is required for cellular function, and that perturbation of this balance results in negative effects associated with a variety of biological processes.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5044-8) contains supplementary material, which is available to authorized users.

RhoA regulates resistance to irinotecan by regulating membrane transporter and apoptosis signaling in colorectal cancer

Colorectal cancer (CRC) is a major cause of mortality and morbidity worldwide. While surgery remains the mainstay of treatment in early stage CRC, chemotherapy is usually given to prolong the overall survival and improve the quality of life for metastatic colorectal cancer (mCRC). But drug resistance is one of the major hurdles of mCRC treatment, and the underlying mechanisms are still largely unknown. In this study, we show that, compared with parental cells, RhoA is up-regulated in irinotecan (CPT-11)-resistant CRC cells. Furthermore, inhibition of RhoA in drug resistant cells, at least partially, rescues the resistance against irinotecan and increases the sensitivity to other chemotherapeutic drug by inhibiting expression of MDR1, MRP1and GSTP1, promotes apoptosis by suppressing the expression of BCL-XL and Bcl-2 and increasing Bax expression, and significantly decreases side population cells. Our results suggest that, in addition to survival, proliferation, migration, adhesion, cell cycle and gene transcription, RhoA is also involved in chemoresistance by regulating the expression of membrane transporter and apoptosis protein in colorectal cancer. They raise an interesting possibility that the expression of RhoA may indicate a poor prognosis due to the high probability to therapy resistance and, on the other hand, inhibition of RhoA activity and function may overcome chemoresistance and improve the effectiveness of clinical treatment of CRC.

GEAR: A database of Genomic Elements Associated with drug Resistance

Drug resistance is becoming a serious problem that leads to the failure of standard treatments, which is generally developed because of genetic mutations of certain molecules. Here, we present GEAR (A database of Genomic Elements Associated with drug Resistance) that aims to provide comprehensive information about genomic elements (including genes, single-nucleotide polymorphisms and microRNAs) that are responsible for drug resistance. Right now, GEAR contains 1631 associations between 201 human drugs and 758 genes, 106 associations between 29 human drugs and 66 miRNAs, and 44 associations between 17 human drugs and 22 SNPs. These relationships are firstly extracted from primary literature with text mining and then manually curated. The drug resistome deposited in GEAR provides insights into the genetic factors underlying drug resistance. In addition, new indications and potential drug combinations can be identified based on the resistome. The GEAR database can be freely accessed through http://gear.comp-sysbio.org.

Molecular mechanisms of chemoresistance in osteosarcoma (Review)

Due to the emergence of adjuvant and neoadjuvant chemotherapy, the survival rate has been greatly improved in osteosarcoma (OS) patients with localized disease. However, this survival rate has remained unchanged over the past 30 years, and the long-term survival rate for OS patients with metastatic or recurrent disease remains poor. To a certain extent, the reason behind this may be ascribed to the chemoresistance to anti-OS therapy. Chemoresistance in OS appears to be mediated by numerous mechanisms, which include decreased intracellular drug accumulation, drug inactivation, enhanced DNA repair, perturbations in signal transduction pathways, apoptosis- and autophagy-related chemoresistance, microRNA (miRNA) dysregulation and cancer stem cell (CSC)-mediated drug resistance. In addition, methods employed to circumvent these resistance mechanism have been shown to be effective in the treatment of OS. However, almost all the current studies on the mechanisms of chemoresistance in OS are in their infancy. Further studies are required to focus on the following aspects: i) Improving the delivery of efficacy through novel delivery patterns; ii) improving the understanding of the signal transduction pathways that regulate the proliferation and growth of OS cells; iii) elucidating the signaling pathways of autophagy and its association with apoptosis in OS cells; iv) utilizing high-throughput miRNA expression analysis to identify miRNAs associated with chemoresistance in OS; and v) identifying the role that CSCs play in tumor metastasis and in-depth study of the mechanism of chemoresistance in the CSCs of OS.

Targeting the phosphoinositide 3-kinase p110-α isoform impairs cell proliferation, survival, and tumor growth in small cell lung cancer

PURPOSE

The phosphoinositide 3-kinase (PI3K) pathway is fundamental for cell proliferation and survival and is frequently altered and activated in neoplasia, including carcinomas of the lung. In this study, we investigated the potential of targeting the catalytic class I(A) PI3K isoforms in small cell lung cancer (SCLC), which is the most aggressive of all lung cancer types.

EXPERIMENTAL DESIGN

The expression of PI3K isoforms in patient specimens was analyzed. The effects on SCLC cell survival and downstream signaling were determined following PI3K isoform inhibition by selective inhibitors or downregulation by siRNA.

RESULTS

Overexpression of the PI3K isoforms p110-α and p110-β and the antiapoptotic protein Bcl-2 was shown by immunohistochemistry in primary SCLC tissue samples. Targeting the PI3K p110-α with RNA interference or selective pharmacologic inhibitors resulted in strongly affected cell proliferation of SCLC cells in vitro and in vivo, whereas targeting p110-β was less effective. Inhibition of p110-α also resulted in increased apoptosis and autophagy, which was accompanied by decreased phosphorylation of Akt and components of the mTOR pathway, such as the ribosomal S6 protein, and the eukaryotic translation initiation factor 4E-binding protein 1. A DNA microarray analysis revealed that p110-α inhibition profoundly affected the balance of pro- and antiapoptotic Bcl-2 family proteins. Finally, p110-α inhibition led to impaired SCLC tumor formation and vascularization in vivo.

CONCLUSION

Together our data show the key involvement of the PI3K isoform p110-α in the regulation of multiple tumor-promoting processes in SCLC.

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

While chemotherapy provides useful palliation, advanced lung cancer remains incurable since those tumors that are initially sensitive to therapy rapidly develop acquired resistance. Resistance may arise from impaired drug delivery, extracellular factors, decreased drug uptake into tumor cells, increased drug efflux, drug inactivation by detoxifying factors, decreased drug activation or binding to target, altered target, increased damage repair, tolerance of damage, decreased proapoptotic factors, increased antiapoptotic factors, or altered cell cycling or transcription factors. Factors for which there is now substantial clinical evidence of a link to small cell lung cancer (SCLC) resistance to chemotherapy include MRP (for platinum-based combination chemotherapy) and MDR1/P-gp (for non-platinum agents). SPECT MIBI and Tc-TF scanning appears to predict chemotherapy benefit in SCLC. In non-small cell lung cancer (NSCLC), the strongest clinical evidence is for taxane resistance with elevated expression or mutation of class III beta-tubulin (and possibly alpha tubulin), platinum resistance and expression of ERCC1 or BCRP, gemcitabine resistance and RRM1 expression, and resistance to several agents and COX-2 expression (although COX-2 inhibitors have had minimal impact on drug efficacy clinically). Tumors expressing high BRCA1 may have increased resistance to platinums but increased sensitivity to taxanes. Limited early clinical data suggest that chemotherapy resistance in NSCLC may also be increased with decreased expression of cyclin B1 or of Eg5, or with increased expression of ICAM, matrilysin, osteopontin, DDH, survivin, PCDGF, caveolin-1, p21WAF1/CIP1, or 14-3-3sigma, and that IGF-1R inhibitors may increase efficacy of chemotherapy, particularly in squamous cell carcinomas. Equivocal data (with some positive studies but other negative studies) suggest that NSCLC tumors with some EGFR mutations may have increased sensitivity to chemotherapy, while K-ras mutations and expression of GST-pi, RB or p27kip1 may possibly confer resistance. While limited clinical data suggest that p53 mutations are associated with resistance to platinum-based therapies in NSCLC, data on p53 IHC positivity are equivocal. To date, resistance-modulating strategies have generally not proven clinically useful in lung cancer, although small randomized trials suggest a modest benefit of verapamil and related agents in NSCLC.

Platinum-DNA interactions and subsequent cellular processes controlling sensitivity to anticancer platinum complexes

Platinum-based compounds are widely used as chemotherapeutics for the treatment of a variety of cancers. The anticancer activity of cisplatin and other platinum drugs is believed to arise from their interaction with DNA. Several cellular pathways are activated in response to this interaction, which include recognition by high-mobility group and repair proteins, translesion synthesis by polymerases, and induction of apoptosis. The apoptotic process is regulated by activation of caspases, p53 gene, and several proapoptotic and antiapoptotic proteins. Such cellular processing eventually leads to an inhibition of the replication or transcription machinery of the cell. Deactivation of platinum drugs by thiols, increased nucleotide excision repair of Pt-DNA adducts, decreased mismatch repair, and defective apoptosis result in resistance to platinum therapy. The differences in cytotoxicity of various platinum complexes are attributed to the differential recognition of their adducts by cellular proteins. Cisplatin and oxaliplatin both produce mainly 1,2-GG intrastrand cross-links as major adducts, but oxaliplatin is found to be more active particularly against cisplatin-resistant tumor cells. Mismatch repair and replicative bypass appear to be the processes most likely involved in differentiating the molecular responses to these two agents. This review describes the formation of Pt-DNA adducts, their interaction with cellular components, and biological effects of this interaction.

A genomic approach to identify molecular pathways associated with chemotherapy resistance

Resistance to chemotherapy in cancer is common. As gene expression profiling has been shown to anticipate chemotherapeutic resistance, we sought to identify cellular pathways associated with resistance to facilitate effective combination therapy. Gene set enrichment analysis was used to associate pathways with resistance in two data sets: the NCI-60 cancer cell lines deemed sensitive and resistant to specific chemotherapeutic agents (Adriamycin, cyclophosphamide, docetaxel, etoposide, 5-fluorouracil, paclitaxel, and topotecan) and a series of 40 lung cancer cell lines for which sensitivity to cisplatin and docetaxel was determined. Candidate pathways were further screened in silico using the Connectivity Map. The lead candidate pathway was functionally validated in vitro. Gene set enrichment analysis associated the matrix metalloproteinase, p53, methionine metabolism, and free pathways with cytotoxic resistance in the NCI-60 cell lines across multiple agents, but no gene set was common to all drugs. Analysis of the lung cancer cell lines identified the bcl-2 pathway to be associated with cisplatin resistance and the AKT pathway enriched in cisplatin- and docetaxel-resistant cell lines. Results from Connectivity Map supported an association between phosphatidylinositol 3-kinase/AKT and docetaxel resistance but did not support the association with cisplatin. Targeted inhibition of the phosphatidylinositol 3-kinase/AKT pathway with LY294002, in combination with docetaxel, resulted in a synergistic effect in previously docetaxel-resistant cell lines but not with cisplatin. These results support the use of a genomic approach to identify drug-specific targets associated with the development of chemotherapy resistance and underscore the importance of disease context in identifying these pathways.

Clinical significance of the p53 pathway and associated gene therapy in non-small cell lung cancers

Many molecules, including several regulators and various target genes, are involved in the biological functions of p53, thus making the p53 pathway rather complicated. However, recent clinical studies have demonstrated that most human cancers have an abnormality in some of the molecules associated with the p53 pathway. Most non-small cell lung cancers (NSCLCs) have either mutations of p53, a reduced p14 alternate reading frame expression, a reduced herpesvirus-associated ubiquitin-specific protease expression or a reduced p33 inhibitor of growth gene1b expression. As a result, the balance of expression of p53 target genes, such as p21, Bax and PUMA, regulates the biological behavior and determines the fate of tumor cells. To date, many studies on cancer gene therapy using these molecules associated with the p53 pathway have been performed to develop new strategies for treating NSCLC patients. Thus, the establishment of a comprehensive and simple evaluation protocol for the p53 pathway is required for clinical use.

Loss of Kv and MaxiK currents associated with increased MRP1 expression in small cell lung carcinoma

Regulatory volume decrease and exocrine secretion studies suggest a functional relationship between K+ and organic anion efflux. To test the hypothesis that the expression of K+ channels and MRP1 is reciprocally related, we employed the patch clamp and RT-PCR techniques on weakly (H69) and strongly MRP1-expressing (H69AR) small cell lung cancer cells. H69AR cells do not express the time- and voltage-dependent delayed rectifying K+ current (Kv) reported earlier in H69 cells and confirmed here. About 80% of the Kv current in H69 cells inactivated at 0 mV, allowing us to identify other K+ currents present in these cells. Whole-cell currents from cells dialyzed and bathed in K-gluconate as the major ions exhibited inward rectification in both cell types. Inwardly rectifying (Kir) currents in both H69 and H69AR cells showed time-dependent activation and slow inactivation at large negative potentials. H69 cells also express a threefold larger Ca2+ -stimulated K+ -selective and iberiotoxin-sensitive current relative to H69AR cells. In excised inside-out patches exposed to 145 mM symmetrical K+ solutions, H69 cells expressed a voltage- and Ca2+ -sensitive large conductance (128 +/- 5 pS) K+ channel (MaxiK). MaxiK-like currents were not observed at the whole-cell or single-channel level in H69AR cells. RT-PCR identified MaxiKalpha transcripts in H69 but not H69AR cells. These results indicate that two K+ currents (MaxiK and Kv) and the organic anion transporter MRP1 are reciprocally expressed in H69 and H69AR cells.

DNA strand breaks and apoptosis induced by oxaliplatin in cancer cells

Platinum anticancer drugs, such as cisplatin, are thought to exert their activity by DNA damage. Oxaliplatin, a clinically active diaminocyclohexane platinum compound, however, requires fewer DNA-Pt adducts than cisplatin to achieve cell growth inhibition. Here we investigated whether secondary DNA damage and apoptotic responses to oxaliplatin compensate for the reduced formation of DNA adducts. Oxaliplatin treatment of leukemic CEM and ovarian A2780 cancer cells resulted in early (4 hr) induction of DNA single-strand breaks measured by nucleoid sedimentation. These infrequent early lesions progress with time into massive double-stranded DNA fragmentation (fragments >50k bp) paralleled by characteristic apoptotic changes revealed by cell morphology and multivariate flow cytometry. Profound oxaliplatin-induced apoptotic DNA fragmentation was detectable following a 24 hr treatment of A2780 and CEM cells with 2 and 10 microM oxaliplatin, respectively. This DNA fragmentation was inhibited completely by the broad-spectrum caspase inhibitor Z-VAD-fmk. Cisplatin, which forms markedly more DNA-Pt adducts in CEM and A2780 cells than equimolar oxaliplatin, was similarly potent as oxaliplatin in terms of early strand breaks and later apoptotic responses. Oxaliplatin was also profoundly apoptotic in several other tumor cell lines of prostate origin but had only a marginal effect in normal prostate PrEC cells. Collectively, the results demonstrate that, relative to the magnitude of the primary DNA-Pt lesions, oxaliplatin is disproportionately more potent than cisplatin in the induction of apoptosis. Apoptosis induction, possibly enhanced by a contribution of targets other than DNA, seems to be an important factor in the mechanism of action of oxaliplatin.