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

Selective inhibitors of nuclear export (SINE)--a novel class of anti-cancer agents

Dysregulation of the nucleo-cytoplasmic transport of proteins plays an important role in carcinogenesis. The nuclear export of proteins depends on the activity of transport proteins, exportins. Exportins belong to the karyopherin β superfamily. Exportin-1 (XPO1), also known as chromosomal region maintenance 1 (CRM1), mediates transport of around 220 proteins. In this review, we summarized the development of a new class of antitumor drugs, collectively known as selective inhibitors of nuclear export (SINE). KPT-330 (selinexor) as an oral agent is showing activities in early clinical trials in both solid tumors and hematological malignancies.

E2F1 drives chemotherapeutic drug resistance via ABCG2

Multidrug resistance is a major barrier against successful chemotherapy, and this has been shown in vitro to be often caused by ATP-binding cassette (ABC) transporters. These transporters are frequently overexpressed in human cancers and confer an adverse prognosis in many common malignancies. The genetic factors, however, that initiate their expression in cancer are largely unknown. Here we report that the major multidrug transporter ABCG2 (BCRP/MXR) is directly and specifically activated by the transcription factor E2F1--a factor perturbed in the majority of human cancers. E2F1 regulates ABCG2 expression in multiple cell systems, and, importantly, we have identified a significant correlation between elevated E2F1 and ABCG2 expression in human lung cancers. We show that E2F1 causes chemotherapeutic drug efflux both in vitro and in vivo via ABCG2. Furthermore, the E2F1-ABCG2 axis suppresses chemotherapy-induced cell death that can be restored by the inhibition of ABCG2. These findings therefore identify a new axis in multidrug resistance and highlight a radical new function of E2F1 that is relevant to tumor therapy.

Long noncoding RNA expression profiles of lung adenocarcinoma ascertained by microarray analysis

Background

Long noncoding RNAs (lncRNAs) have been shown to be involved in the development and progression of lung cancer. However, the roles of lncRNAs in lung cancer are not well understood.

Methodology/Principal Findings

We used a high-throughput microarray to compare the lncRNA and messenger RNA (mRNA) expression profiles in lung adenocarcinoma and normal tissue (NT) samples. Several candidate adenocarcinoma-associated lncRNAs were verified by real-time quantitative reverse transcription polymerase chain reaction (PCR) analysis. Using abundant and varied probes, we were able to assess 30,586 lncRNAs and 26,109 mRNAs in our microarray. We found that 2,420 lncRNAs and 1,109 mRNAs were differentially expressed (≥2-fold change) in lung adenocarcinoma samples and NT, indicating that many lncRNAs were significantly upregulated or downregulated in lung adenocarcinoma. We also found, via quantitative PCR, that 19 lncRNAs were aberrantly expressed in lung adenocarcinoma compared with matched histologically normal lung tissues. Among these, LOC100132354 and RPLP0P2 were the most aberrantly expressed lncRNAs, as estimated by quantitative PCR in 100 pairs of lung adenocarcinoma and NT samples.

Conclusions/Significance

Our study ascertained the expression patterns of lncRNAs in lung adenocarcinoma by microarray. The results revealed that many lncRNAs were differentially expressed in lung adenocarcinoma tissues and NT, suggesting that they may play a key role in tumor development.

KPT-330 has antitumour activity against non-small cell lung cancer

BACKGROUND

We investigated the biologic and pharmacologic activities of a chromosome region maintenance 1 (CRM1) inhibitor against human non-small cell lung cancer (NSCLC) cells both in vitro and in vivo.

METHODS

The in vitro and in vivo effects of a novel CRM1 inhibitor (KPT-330) for a large number of anticancer parameters were evaluated using a large panel of 11 NSCLC cell lines containing different key driver mutations. Mice bearing human NSCLC xenografts were treated with KPT-330, and tumour growth was assessed.

RESULTS

KPT-330 inhibited proliferation and induced cell cycle arrest and apoptosis-related proteins in 11 NSCLC cells lines. Moreover, the combination of KPT-330 with cisplatin synergistically enhanced the cell kill of the NSCLC cells in vitro. Human NSCLC tumours growing in immunodeficient mice were markedly inhibited by KPT-330. Also, KPT-330 was effective even against NSCLC cells with a transforming mutation of either exon 20 of EGFR, TP53, phosphatase and tensin homologue, RAS or PIK3CA, suggesting the drug might be effective against a variety of lung cancers irrespective of their driver mutation.

CONCLUSIONS

Our results support clinical testing of KPT-330 as a novel therapeutic strategy for NSCLC.

Investigation of the epidermal growth factor receptor mutation rate in non-small cell lung cancer patients and the analysis of associated risk factors using logistic regression

The aim of the present study was to investigate the mutation rate of the epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) patients and to apply logistic regression analysis to investigate the factors associated with EGFR gene mutation to provide data for the treatment of NSCLC. Paraffin tissue, bronchoscopy or pleural effusion specimens were collected from 176 NSCLC patients following pathological diagnosis. The EGFR gene exon 19 delL747-S75linss and delL747-S752ins deletion mutations, and the exon 20 T790M and exon 21 L858R mutations were identified using amplification refractory mutation system analysis. The clinical data and laboratory results of the patients were collected, and the total mutation rate of the EGFR gene in exons 19, 20 and 21 in the 176 NSCLC patients was found to be 48.3% (85/176). In addition, the EGFR gene mutation rate in adenocarcinoma was found to be significantly higher than that in squamous cell and large cell carcinoma (χ²=12.454; P=0.002). Furthermore, the mutation rate was found to be significantly higher in females than in males (χ²=13.78; P=0.001). The rate of exon 19 mutation was 21.0% (37/176), whereas the rate of exon 20 T90M mutation was 1.7% (3/176) and that of exon 21 L858R mutation was 29.0% (51/176). The logistic regression analysis revealed that the female gender, adenocarcinoma, distant metastasis and chemotherapy are factors associated with EGFR gene mutation (P<0.05). The female gender resulted in an increased incidence (2.438 times that of males) of EGFR mutation. Similarly, adenocarcinoma, distant metastasis and chemotherapy exhibited an increase in EGFR mutation risk (by 2.571, 2.810 and 0.367 times, respectively). The rate of EGFR mutation was high in the NSCLC patients, predominantly in exons 21 and 19. Therefore, these factors (female gender, adenocarcinoma, distant metastasis and chemotherapy) may increase the probability of EGFR gene mutations.

Copper transporter CTR1 expression and tissue platinum concentration in non-small cell lung cancer

BACKGROUND

Platinum resistance is a major limitation in the treatment of advanced non-small cell lung cancer (NSCLC). We previously demonstrated that low tissue platinum concentration in NSCLC specimens was significantly associated with reduced tumor response. Furthermore, low expression of the copper transporter CTR1, a transporter of platinum uptake was associated with poor clinical outcome following platinum-based therapy in NSCLC patients. We investigated the relationship between tissue platinum concentrations and CTR1 expression in NSCLC specimens.

METHODS

We identified paraffin-embedded NSCLC tissue blocks of known tissue platinum concentrations from 30 patients who underwent neoadjuvant platinum-based chemotherapy at MD Anderson Cancer Center. Expression of CTR1 in tumors and normal adjacent lung specimens was determined by immunohistochemistry with adequate controls.

RESULTS

Tissue platinum concentration significantly correlated with tumor response in 30 patients who received neoadjuvant platinum-based chemotherapy (P<0.001). CTR1 was differentially expressed in NSCLC tumors. A subset of patients with undetectable CTR1 expression in their tumors had reduced platinum concentrations (P=0.058) and tumor response (P=0.016) compared to those with any level of CTR1 expression. We also observed that African Americans had significantly reduced CTR1 expression scores (P=0.001), tissue platinum concentrations (P=0.009) and tumor shrinkage (P=0.016) compared to Caucasians.

CONCLUSIONS

To our best knowledge this is the first study investigating the function of CTR1 in clinical specimens. CTR1 expression may be necessary for therapeutic efficacy of platinum drugs, consistent with previous preclinical studies. A prospective clinical trial is necessary to develop CTR1 into a potential biomarker for platinum drugs.

The prognostic role of the class III β-tubulin in non-small cell lung cancer (NSCLC) patients receiving the taxane/vinorebine-based chemotherapy: a meta-analysis

Background

A number of studies have examined the relationship between the expression of the class III β-tubulin (TUBB3) and the treatment responses to the taxane/vinorebine-based chemotherapy in patients with non-small cell lung cancer (NSCLC). However, the results of these studies were inconsistent and inconclusive. Therefore, we conducted an up-to-date meta-analysis to evaluate the prognostic role of TUBB3 in the taxane/vinorebine-based chemotherapy.

Methods

A literature search for relevant studies was conducted in PubMed, Embase, and CNKI. The inclusion criteria were the taxane/vinorebine-based chemotherapy in patients with NSCLC and the evaluation of the clinical outcomes in relation to the expression of TUBB3. The clinical outcomes analyzed in this study included the overall response rate (ORR), overall survival (OS), and event-free survival (EFS). Odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) were calculated to assess the risk associated with the TUBB3 expression in the taxane/vinorebine-based chemotherapy.

Results

A total of 28 studies with 2401 NSCLC patients were qualified for this meta-analysis. We found that the positive or high level of TUBB3 expression was associated with a poorer ORR (OR = 0.24, 95% CI = 0.16–0.36, p<0.001), an unfavorable OS (HR = 1.52, 95% CI = 1.27–1.82, p<0.001), and a worse EFS (HR = 1.47, 95% CI = 1.24–1.74, p<0.001) compared to the negative or low level of TUBB3 expression. The statistically significant associations between TUBB3 and chemotherapy responses were also observed in the stratified subgroup analysis, which included the analysis by ethnic subgroup (Asian and Caucasian), chemotherapy regimen (taxane-based and vinorebine-based), TUBB3 detection method (IHC and PCR), and treatment strategy (surgery plus adjuvant chemotherapy and palliative chemotherapy).

Conclusions

The expression level of TUBB3 may be a useful biomarker to predict the clinical outcomes of the taxane/vinorebine-based chemotherapy in patients with NSCLC.

Decitabine impact on the endocytosis regulator RhoA, the folate carriers RFC1 and FOLR1, and the glucose transporter GLUT4 in human tumors

Background

In 31 solid tumor patients treated with the demethylating agent decitabine, we performed tumor biopsies before and after the first cycle of decitabine and used immunohistochemistry (IHC) to assess whether decitabine increased expression of various membrane transporters. Resistance to chemotherapy may arise due to promoter methylation/downregulation of expression of transporters required for drug uptake, and decitabine can reverse resistance in vitro. The endocytosis regulator RhoA, the folate carriers FOLR1 and RFC1, and the glucose transporter GLUT4 were assessed.

Results

Pre-decitabine RhoA was higher in patients who had received their last therapy >3 months previously than in patients with more recent prior therapy (P = 0.02), and varied inversely with global DNA methylation as assessed by LINE1 methylation (r = −0.58, P = 0.006). Tumor RhoA scores increased with decitabine (P = 0.03), and RFC1 also increased in patients with pre-decitabine scores ≤150 (P = 0.004). Change in LINE1 methylation with decitabine did not correlate significantly with change in IHC scores for any transporter assessed. We also assessed methylation of the RFC1 gene (alias SLC19A1). SLC19A1 methylation correlated with tumor LINE1 methylation (r = 0.45, P = 0.02). There was a small (statistically insignificant) decrease in SLC19A1 methylation with decitabine, and there was a trend towards change in SLC19A1 methylation with decitabine correlating with change in LINE1 methylation (r = 0.47, P <0.15). While SLC19A1 methylation did not correlate with RFC1 scores, there was a trend towards an inverse correlation between change in SLC19A1 methylation and change in RFC1 expression (r = −0.45, P = 0.19).

Conclusions

In conclusion, after decitabine administration, there was increased expression of some (but not other) transporters that may play a role in chemotherapy uptake. Larger patient numbers will be needed to define the extent to which this increased expression is associated with changes in DNA methylation.

Osteopontin is associated with decreased apoptosis and αv integrin expression in lung adenocarcinoma

Osteopontin (OPN) is a glycoprotein involved in invasion, progression and metastasis of many carcinomas. It contains several functional domains including binding sites for αv integrins, cell surface molecules playing a major role in mediating cell migration and adhesion. The aim of the study was to evaluate the expression of osteopontin in human non-small cell lung cancer (NSCLC) and to determine its possible prognostic significance as well as relation to apoptosis and αv integrin expression. We analyzed 111 surgically resected NSCLC for immunohistochemical expression of OPN and αv integrin. OPN expression was compared to apoptotic rate and clinicopathological parameters such as tumor size, histological grade, lymph node status, pT, and TNM stage. Apoptotic rate was measured by TUNEL staining method. OPN expression in NSCLC was significantly higher in lung adenocarcinomas (AC) then in squamous cell carcinomas (p<0.001). There was no correlation between OPN expression and clinicopathological parameters. The level of OPN expression in AC was associated with decreased apoptotic activity of tumor cells (p=0.006), and correlated with αv integrin expression (p=0.048), particularly in low stage tumors (p=0.013). Prolonged tumor cell survival in lung AC due to OPN and αv integrin overexpression may have an impact on tumor progression and resistance to therapy.

RHOB influences lung adenocarcinoma metastasis and resistance in a host-sensitive manner

Lung adenocarcinoma (ADC) is the most common lung cancer subtype and presents a high mortality rate. Clinical recurrence is often associated with the emergence of metastasis and treatment resistance. The purpose of this study was to identify genes with high prometastatic activity which could potentially account for treatment resistance. Global transcriptomic profiling was performed by robust microarray analysis in highly metastatic subpopulations. Extensive in vitro and in vivo functional studies were achieved by overexpression and by silencing gene expression. We identified the small GTPase RHOB as a gene that promotes early and late stages of metastasis in ADC. Gene silencing of RHOB prevented metastatic activity in a systemic murine model of bone metastasis. These effects were highly dependent on tumor-host interactions. Clinical analysis revealed a marked association between high RHOB levels and poor survival. Consistently, high RHOB levels promote metastasis progression, taxane-chemoresistance, and contribute to the survival advantage to γ-irradiation. We postulate that RHOB belongs to a novel class of "genes of recurrence" that have a dual role in metastasis and treatment resistance.

Nanotechnology approaches for personalized treatment of multidrug resistant cancers

The efficacy of chemotherapy is substantially limited by the resistance of cancer cells to anticancer drugs that fluctuates significantly in different patients. Under identical chemotherapeutic protocols, some patients may receive relatively ineffective doses of anticancer agents while other individuals obtain excessive amounts of drugs that induce severe adverse side effects on healthy tissues. The current review is focused on an individualized selection of drugs and targets to suppress multidrug resistance. Such selection is based on the molecular characteristics of a tumor from an individual patient that can potentially improve the treatment outcome and bring us closer to an era of personalized medicine.

Therapy-induced enrichment of putative lung cancer stem-like cells

Tumour drug resistance is a major issue in the management of lung cancer patients as almost all lung tumours are either intrinsically resistant or quickly develop acquired resistance to chemotherapeutic drugs. Cancer drug resistance has recently been linked, at least in part, to the existence of cancer stem-like cells (CSLCs), a small sub-population of cells within the tumour that possess stem-like properties. CSLCs are often isolated by fluorescence activated cell sorting (FACS) according to the expression of certain stem-like cell membrane markers. Conflicting results regarding the specificity of particular stem cell surface markers for isolating CSLCs have, however, been recently reported. Therefore, alternative strategies enabling the identification and study of CSLCs should be considered, particularly in tumour types where appropriate stem cell markers are not well established and validated, like in lung cancer. In this article, we review data indicating therapy-selection as a valid approach for putative lung CSLCs enrichment. We believe that this strategy would be determinant for correctly assessing and characterising the sub-populations of CSLCs that are able to survive chemo or radiotherapy regimens and, at the same time, also have the ability to recapitulate and sustain tumour growth. Using therapy-induced enrichment of CSLCs may, therefore, prove to be an extremely useful method for studying CSLCs and provide new clues regarding potential therapeutic targets for their efficient elimination, which will undoubtedly play a decisive role in improving lung cancer patients' survival.

Inhibition of Raf-MEK-ERK and hypoxia pathways by Phyllanthus prevents metastasis in human lung (A549) cancer cell line

BACKGROUND

Lung cancer constitutes one of the malignancies with the greatest incidence and mortality rates with 1.6 million new cases and 1.4 million deaths each year. Prognosis remains poor due to deleterious development of multidrug resistance resulting in less than 15% lung cancer patients reaching five years survival. We have previously shown that Phyllanthus induced apoptosis in conjunction with its antimetastastic action. In the current study, we aimed to determine the signaling pathways utilized by Phyllanthus to exert its antimetastatic activities.

METHODS

Cancer 10-pathway reporter array was performed to screen the pathways affected by Phyllanthus in lung carcinoma cell line (A549) to exert its antimetastatic effects. Results from this array were then confirmed with western blotting, cell cycle analysis, zymography technique, and cell based ELISA assay for human total iNOS. Two-dimensional gel electrophoresis was subsequently carried out to study the differential protein expressions in A549 after treatment with Phyllanthus.

RESULTS

Phyllanthus was observed to cause antimetastatic activities by inhibiting ERK1/2 pathway via suppression of Raf protein. Inhibition of this pathway resulted in the suppression of MMP2, MMP7, and MMP9 expression to stop A549 metastasis. Phyllanthus also inhibits hypoxia pathway via inhibition of HIF-1α that led to reduced VEGF and iNOS expressions. Proteomic analysis revealed a number of proteins downregulated by Phyllanthus that were involved in metastatic processes, including invasion and mobility proteins (cytoskeletal proteins), transcriptional proteins (proliferating cell nuclear antigen; zinc finger protein), antiapoptotic protein (Bcl2) and various glycolytic enzymes. Among the four Phyllanthus species tested, P. urinaria showed the greatest antimetastatic activity.

CONCLUSIONS

Phyllanthus inhibits A549 metastasis by suppressing ERK1/2 and hypoxia pathways that led to suppression of various critical proteins for A549 invasion and migration.

The network of P-glycoprotein and microRNAs interactions

Overexpression of P-glycoprotein (P-gp) contributes to the multidrug resistance (MDR) phenotype found in many cancer cells. P-gp has been identified as a promising molecular target, although attempts to find successful therapies to counteract its function as a drug efflux pump have largely failed to date. Apart from its role in drug efflux, P-gp may have other cellular functions such as being involved in apoptosis, and is found in various locations in the cell. Its expression is highly regulated, namely by microRNAs (miRNAs or miRs). In addition, P-gp may regulate the expression of miRs in the cell. Furthermore, both P-gp and miRs may be found in microvesicles or exosomes and may be transported to neighboring, drug-sensitive cells. Here, we review this current issue together with recent evidence of this network of interactions between P-gp and miRs.

The cell's nucleolus: an emerging target for chemotherapeutic intervention

The transient nucleolus plays a central role in the up-regulated synthesis of ribosomal RNA (rRNA) to sustain ribosome biogenesis, a hallmark of aberrant cell growth. This function, in conjunction with its unique pathohistological features in malignant cells and its ability to mediate apoptosis, renders this sub-nuclear structure a potential target for chemotherapeutic agents. In this Minireview, structurally and functionally diverse small molecules are discussed that have been reported to either interact with the nucleolus directly or perturb its function indirectly by acting on its dynamic components. These molecules include all major classes of nucleic-acid-targeted agents, antimetabolites, kinase inhibitors, anti-inflammatory drugs, natural product antibiotics, oligopeptides, as well as nanoparticles. Together, these molecules are invaluable probes of structure and function of the nucleolus. They also provide a unique opportunity to develop novel strategies for more selective and therefore better-tolerated chemotherapeutic intervention. In this regard, inhibition of RNA polymerase-I-mediated rRNA synthesis appears to be a promising mechanism for killing cancer cells. The recent development of molecules targeted at G-quadruplex-forming rRNA gene sequences, which are currently undergoing clinical trials, seems to attest to the success of this approach.

Antitumor effects of naturally occurring oligomeric resveratrol derivatives

This study was designed to evaluate and characterize the molecular basis of antitumor activity of naturally occurring resveratrol (RES; 3,5,4'-trihydroxy-trans-stilbene) derivatives. The compounds were isolated from plants in previous studies and characterized spectroscopically. The antitumor activities of 31 RES derivatives, including dimers, trimers, and tetramers of RES, were evaluated using cell-based assays and validated on a murine model. Several trimeric and a tetrameric stilbenoids induced tumor cell apoptosis or growth arrest of several tumor cell lines with IC50 values (2.8-19.7 μM), significantly lower than that of RES (IC50>70 μM). Using pauciflorol B (PauB) as an example, we showed that the compound induced apoptosis p53 dependently, inducing p53 accumulation and p53-modulated gene expression in cells with wild-type p53, but not in those with nonfunctional p53. Reexpression of p53 in p53-null cells rescued cell death response. In parallel, the MAPK/p38 was activated and critical for PauB-induced killing. Interestingly, activation of p38 in p53 deficient cells was sufficient to drive cells into senescence via the p16-pRb pathway. Finally, PauB dose-dependently inhibited tumor growth on nude mice. Naturally occurring trimeric and tetrameric stilbenoids are potent antitumor agents. Those compounds exert antitumor effect through p53-dependent induction of apoptosis or senescence.

Fool's gold, lost treasures, and the randomized clinical trial

Background

Randomized controlled trials with a survival endpoint are the gold standard for clinical research, but have failed to achieve cures for most advanced malignancies. The high costs of randomized clinical trials slow progress (thereby causing avoidable loss of life) and increase health care costs.

Discussion

A malignancy may be caused by several different mutations. Therapies effective vs one mutation may be discarded due to lack of statistical significance across the entire population. Conversely, expensive large randomized trials may have sufficient statistical power to demonstrate benefit despite the therapy only working in subgroups. Non-cost-effective therapy is then applied to all patients (including subgroups it cannot help). Randomized trials comparing therapies with different mechanisms of action are misleading since they may conclude the therapies are “equivalent” despite benefitting different subpopulations, or may erroneously conclude that one therapy is superior simply because it targets a larger subpopulation. Furthermore, minor variances in patient selection may determine study outcome, a therapy may be discarded as ineffective despite substantial benefit in one subpopulation if harmful in another, randomized trials may more effectively detect therapies with minor benefit in most patients vs marked benefit in subpopulations, and randomized trials in unselected patients may erroneously conclude that “shot-gun” combinations are superior to single agents when sequential administration of personalized single agents might work better and spare patients treatment with drugs that cannot help them. We must identify predictive biomarkers early by comparing responding to progressing patients in phase I-II trials. Enriching randomized trials for biomarker-positive patients can markedly reduce required patient numbers and costs despite expensive screening for biomarker-positive patients. Available data support approval of new drugs without randomized trials if they yield single-agent sustained responses in patients refractory to standard therapies. Conversely, new approaches are needed to guide development of drug combinations since both standard phase II approaches and phase II-III randomized trials have a high risk of misleading.

Summary

Traditional randomized clinical trials approaches are often inefficient, wasteful, and unreliable. New clinical research paradigms are needed. The primary outcome of clinical research should be “Who (if anyone) benefits?” rather than “Does the overall group benefit?”

The diagnostic value of apolipoprotein E in malignant pleural effusion associated with non-small cell lung cancer

BACKGROUND

Apolipoprotein E (apoE) levels have been shown to be elevated in pleural effusion of patients with non-small cell lung cancer (NSCLC). However, the diagnostic value of apoE in pleural effusion in NSCLC has not been well validated and established.

METHODS

Samples of malignant pleural effusions (MPE) and benign effusions were collected and analyzed for apoE, tumor markers, and other biochemical changes.

RESULTS

ApoE levels were significantly higher in MPE (n=160) than in benign pleural effusions (n=40). They were higher in adenocarcinoma-associated MPE than in squamous cell carcinoma- and large cell carcinoma-associated MPE. The receiver operating characteristic curve showed that the sensitivity and specificity of apoE for the diagnosis of MPE were 87.5% and 85.3%, respectively, at the cutoff 105 ng/ml, and the area under the curve (AUC) was 0.748. For the diagnosis of adenocarcinoma-associated MPE, apoE achieved sensitivity and specificity of 70.8% and 83.30%, respectively, and the AUC was the highest of all the markers.

CONCLUSIONS

ApoE levels are significantly increased in the pleural effusion of patients with NSCLC. Increased concentration of apoE in a pleural effusion is a potential marker for the diagnosis of MPE as well as for differential diagnosis of MPE in NSCLC.

Multidrug resistance in primary tumors and metastases in patients with esophageal squamous cell carcinoma

Studies have demonstrated that radical esophagectomy can significantly prolong disease-free survival and improve the survival rate of patients with T3 or T4 esophageal cancer and lymph node metastasis. Multidrug resistant cancer cells have active efflux mechanisms that prevent the accumulation of chemotherapeutic drugs in the cells. The purpose of this study was to compare the expression of five MDR related proteins between primary tumors in patients with thoracic esophageal squamous cell carcinoma (ESCC) and metastatic cancer in lymph nodes to explore the clinical significance of heterogeneity in MDR metastatic cancer cells. Fifty-four patients with ESCC and lymph node metastasis were included. All patients underwent subtotal esophagectomy and D2/D3 lymph node resection. The expression of lung resistance-related protein (LRP), P-glycoprotein, topoisomerase-II, thymidylate synthase, and glutathione S-transferase P1-1 (GST-π) were determined in the primary tumors and lymph nodes via immunohistochemistry. The expression of LRP was significantly different between the primary tumors and lymph nodes (P = 0.026). No significant differences were found for the other four proteins, and protein expression was not associated with either degree of differentiation or disease stage. It was also found that GST-π was expressed in all patients in both the primary tumors and lymph nodes, suggesting that the design and application of chemotherapeutic protocols capable of reducing GST-π expression may be beneficial for patients with ESCC. Additional research regarding the clinical utility of MDR protein expression in ESCC is warranted to design effective chemotherapeutic protocols.

Overcoming paclitaxel resistance in lung cancer cells via dual inhibition of stathmin and Bcl-2

Lung cancer is the leading cause of death from malignancy in people and over 85% of these patients eventually die from disseminated disease. Paclitaxel (TAX) is widely used as an antimicrotubule agent for the treatment of lung cancer. Unfortunately, the resistance to this antimicrotubule agent occurs frequently. Stathmin (STMN1) is a ubiquitous microtubule destabilizing protein linked to cancer and cell health and its expression level often correlates with cancer stage progression and prognosis for survival. Overexpression of the antiapoptotic protein Bcl-2 has been shown to prolong drug-induced growth arrest, potentially inducing resistance. In this study, we used a short hairpin RNA (shRNA) approach to evaluate the effect of STMN1 and Bcl-2 downregulation in the sensitivity to TAX in lung cancer cells. We achieved significant downregulation of STMN1 and Bcl-2 mRNA and protein expression by a combination of double shRNA treatment strategy. Our experimental data showed that inhibition of STMN1 and Bcl-2 expression with RNA interference can sensitize lung cancer cells to TAX. These findings suggest a novel approach to improve the efficacy of certain antimicrotubule agents against lung cancer by regulating the function of STMN1 and Bcl-2.

Enhanced tumor suppression by adenoviral PTEN gene therapy combined with cisplatin chemotherapy in small-cell lung cancer

DNA-damaging anticancer drug cisplatin (cis-diamminedichloroplatinum) (DDP)-based chemotherapy is the mainstay and standard treatment for small-cell lung cancer (SCLC). However, frequent relapse and chemoresistance of SCLC remains a significant therapeutic hurdle. Tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) as a negative regulator of phosphoinositide 3-kinase/AKT survival pathway exhibits strong tumor-suppressive activities. A combination of chemotherapy and gene therapy (chemogene therapy) is a promising practice in cancer therapy. In this report, we examined the combined antitumor effect of adenovirus-mediated PTEN (AdVPTEN) gene therapy and DDP chemotherapy on PTEN-null NCI-H446 human SCLC cells in vitro and in vivo in athymic BALB/c nude mice. We demonstrated that AdVPTEN plus DDP enhanced growth suppression, cell-cycle G1 phase arrest and apoptosis in in vitro NCI-H446 tumor cells and in vivo NCI-H446 xenografted tumors subcutaneously inoculated in nude mice. Mechanistically, AdVPTEN plus DDP exerted an overlapping effect on upregulation of P53, P21, P27, Bax and Cleaved Caspase-3 as well as downregulation of Bcl-2 and survivin in in vitro and in vivo NCI-H446 tumor cells. Moreover, AdVPTEN plus DDP additively reduced tumor vessel CD34 expression and microvessel density in vivo. The enhanced therapeutic efficacy elicited by AdVPTEN plus DDP was closely associated with additive induction of G1 phase arrest and apoptosis via substantially modulating cell-cycle regulation molecules and activating intrinsic apoptotic pathway through P53 restoration, and overlapping inhibition of tumor angiogenesis. Thus, our results indicated that AdVPTEN combined with DDP may be a novel and effective chemogene therapy modality for human SCLC.

Personalized medicine for targeted and platinum-based chemotherapy of lung and bladder cancer

The personalized medicine revolution is occurring for cancer chemotherapy. Biomarkers are increasingly capable of distinguishing genotypic or phenotypic traits of individual tumors, and are being linked to the selection of treatment protocols. This review covers the molecular basis for biomarkers of response to targeted and cytotoxic lung and bladder cancer treatment with an emphasis on platinum-based chemotherapy. Platinum derivatives are a class of drugs commonly employed against solid tumors that kill cells by covalent attachment to DNA. Platinum-DNA adduct levels in patient tissues have been correlated to response and survival. The sensitivity and precision of adduct detection has increased to the point of enabling subtherapeutic dosing for diagnostics applications, termed diagnostic microdosing, prior to the initiation of full-dose therapy. The clinical status of this unique phenotypic marker for lung and bladder cancer applications is detailed along with discussion of future applications.

Single agent- and combination treatment with two targeted suicide gene therapy systems is effective in chemoresistant small cell lung cancer cells

BACKGROUND

Transcriptional targeted suicide gene (SG) therapy driven by the insulinoma-associated 1 (INSM1) promoter makes it possible to target suicide toxin production and cytotoxicity exclusively to small cell lung cancer (SCLC) cells and tumors. It remains to be determined whether acquired chemoresistance, as observed in the majority of SCLC patients, desensitizes SCLC cells to INSM1 promoter-driven SG therapy.

METHODS

A panel of SCLC cell lines resistant to clinically relevant chemotherapeutics was characterized regarding the expression of proteins involved in response to chemotherapy and regarding INSM1 promoter activity. Sensitivity towards INSM1 promoter-driven SG therapy was tested using different systems: Yeast cytosine deaminase-uracil phosphoribosyl transferase (YCD-YUPRT) in combination with the prodrug 5-fluorocytosine (5-FC) or Escherichia coli nitroreductase (NTR) together with the bromomustard prodrug SN27686.

RESULTS

The chemoresistant cell lines displayed heterogeneous expression profiles of molecules involved in multidrug resistance, apoptosis and survival pathways. Despite this, the INSM1 promoter activity was found to be unchanged or increased in SCLC chemoresistant cells and xenografts compared to chemosensitive variants. INSM1 promoter-driven SG therapy with YCD-YUPRT/5-FC or NTR/SN27686, was found to induce high levels of cytotoxicity in both chemosensitive and chemoresistant SCLC cells. Moreover, the combination of INSM1 promoter-driven YCD-YUPRT/5-FC therapy and chemotherapy, as well as the combination of INSM1 promoter-driven YCD-YUPRT/5-FC and NTR/SN27686 therapy, was observed to be superior to single agent therapy in chemoresistant SCLC cells.

CONCLUSIONS

Collectively, the present study demonstrates that targeted SG therapy is a potent therapeutic approach for chemoresistant SCLC patients, with the highest efficacy achieved when applied as combination SG therapy or in combination with standard chemotherapy.

Specific Biomarkers Are Associated with Docetaxeland Gemcitabine-Resistant NSCLC Cell Lines

Five-year survival rate for lung cancer is limited to 10% to 15%. Therefore, the identification of novel therapeutic prognostic factors is an urgent requirement. The aim of this study is thus to highlight specific biomarkers in chemoresistant non-small cell lung cancer cell lines. Therefore, we checked-in the control condition as well as after short-term pharmacological treatment with either docetaxel or gemcitabine-the expression of genes such as tumor suppressor genes (CDKN2A, DAPK, FHIT, GSTP1, MGMT, RARβ2, RASSF1A, and TIMP3), genes associated with drug resistance (BRCA1, COX2, ERCC1, IGFBP3, RRM1, and TUBB3), and stemness-related genes (CD133, OCT4, and SLUG) in two cellular models of squamous carcinoma (CAEP) and adenocarcinoma (RAL) of the lung originally established. Their promoter methylation profile was also evaluated. Drug-related genes were upregulated. Cisplatin resistance matched with high levels of BRCA1 and ERCC1 in both cell lines; docetaxel sensitivity of CAEP cells was associated to levels of TUBB3 lower than RAL cells. Although CAEP cells were more sensitive to gemcitabine, both cell lines showed high levels of RRM1. Stemness-related genes were downregulated in the control condition but became upregulated in docetaxel-resistant cells, indicating the selection of a population with stemness features. We did not find an unequivocal correspondence between gene expression and respective DNA promoter methylation status, suggesting the involvement of additional mechanisms of gene expression regulation. These results highlight specific biomarkers consistent with the different responses of the two cell lines to standard pharmacological treatments and indicate specific molecular traits for their chemoresistance.

The significance of epigenetic alterations in lung carcinogenesis

Lung cancer is recognized as a leading cause of cancer-related death worldwide and its frequency is still increasing. The prognosis in lung cancer is poor and limited by the difficulties of diagnosis at early stage of disease, when it is amenable to surgery treatment. Therefore, the advance in identification of lung cancer genetic and epigenetic markers with diagnostic and/or prognostic values becomes an important tool for future molecular oncology and personalized therapy. As in case of other tumors, aberrant epigenetic landscape has been documented also in lung cancer, both at early and late stage of carcinogenesis. Hypermethylation of specific genes, mainly tumor suppressor genes, as well as hypomethylation of oncogenes and retrotransposons, associated with histopathological subtypes of lung cancer, has been found. Epigenetic aberrations of histone proteins and, especially, the lower global levels of histone modifications have been associated with poorer clinical outcome in lung cancer. The recently discovered role of epigenetic modifications of microRNA expression in tumors has been also proven in lung carcinogenesis. The identified epigenetic events in lung cancer contribute to its specific epigenotype and correlated phenotypic features. So far, some of them have been suggested to be cancer biomarkers for early detection, disease monitoring, prognosis, and risk assessment. As epigenetic aberrations are reversible, their correction has emerged as a promising therapeutic target.

Genetic association with overall survival of taxane-treated lung cancer patients - a genome-wide association study in human lymphoblastoid cell lines followed by a clinical association study

Background

Taxane is one of the first line treatments of lung cancer. In order to identify novel single nucleotide polymorphisms (SNPs) that might contribute to taxane response, we performed a genome-wide association study (GWAS) for two taxanes, paclitaxel and docetaxel, using 276 lymphoblastoid cell lines (LCLs), followed by genotyping of top candidate SNPs in 874 lung cancer patient samples treated with paclitaxel.

Methods

GWAS was performed using 1.3 million SNPs and taxane cytotoxicity IC50 values for 276 LCLs. The association of selected SNPs with overall survival in 76 small or 798 non-small cell lung cancer (SCLC, NSCLC) patients were analyzed by Cox regression model, followed by integrated SNP-microRNA-expression association analysis in LCLs and siRNA screening of candidate genes in SCLC (H196) and NSCLC (A549) cell lines.

Results

147 and 180 SNPs were associated with paclitaxel or docetaxel IC50s with p-values <10^-4 in the LCLs, respectively. Genotyping of 153 candidate SNPs in 874 lung cancer patient samples identified 8 SNPs (p-value < 0.05) associated with either SCLC or NSCLC patient overall survival. Knockdown of PIP4K2A, CCT5, CMBL, EXO1, KMO and OPN3, genes within 200 kb up-/downstream of the 3 SNPs that were associated with SCLC overall survival (rs1778335, rs2662411 and rs7519667), significantly desensitized H196 to paclitaxel. SNPs rs2662411 and rs1778335 were associated with mRNA expression of CMBL or PIP4K2A through microRNA (miRNA) hsa-miR-584 or hsa-miR-1468.

Conclusions

GWAS in an LCL model system, joined with clinical translational and functional studies, might help us identify genetic variations associated with overall survival of lung cancer patients treated paclitaxel.

Predictive value of ABCB1 polymorphisms G2677T/A, C3435T, and their haplotype in small cell lung cancer patients treated with chemotherapy

PURPOSE

Multiple drug resistance limits the efficacy of numerous cytotoxic drugs used in the treatment of small cell lung cancer (SCLC). The drug efflux protein ATP-binding cassette transporter B1 (ABCB1) has an important role in this process, and its gene variability may affect chemotherapy outcomes.

PATIENTS AND METHODS

This study aimed to evaluate the associations between ABCB1 polymorphisms G2677T/A, C3435T, and their haplotype with progression-free survival (PFS) and overall survival (OS) in 177 SCLC patients treated with cisplatin-etoposide or cyclophosphamide-epirubicin-vincristine chemotherapy. To determine the ABCB1 genotype, allelic specific TaqMan(®) probes were used in a RT-PCR .

RESULTS

Patients carrying the G2677T/A TT + TA + AA genotypes (24 %) or the C3435T CT + TT genotypes (72 %) or the 2677T/A-3435T haplotype (40 %) had a longer PFS (Cox regression, P = 0.052, 0.037 and 0.037, respectively); these associations persisted also in multivariate analyses (Cox regression, P = 0.028, 0.037 and 0.030, respectively). Moreover, patients with the C3435T CT + TT genotypes had a longer OS both in univariate and multivariate analysis (Cox regression, P = 0.022 and 0.028, respectively). A trend toward longer OS was noted for the 2677T/A-3435T haplotype (Cox regression, P = 0.051), but its independent value was not confirmed (Cox regression, P = 0.071).

CONCLUSIONS

Our study reported a possible predictive value of ABCB1 polymorphisms G2677T/A, C3435T, and their haplotype for longer PFS and OS in Caucasian SCLC patients treated with chemotherapy. However, to be implemented into routine clinical practice, ABCB1 polymorphisms require further validation.

Tissue platinum concentration and tumor response in non-small-cell lung cancer

PURPOSE

Platinum resistance is a major limitation in the treatment of advanced non-small-cell lung cancer (NSCLC). Reduced intracellular drug accumulation is one of the most consistently identified features of platinum-resistant cell lines, but clinical data are limited. We assessed the effects of tissue platinum concentrations on response and survival in NSCLC.

PATIENTS AND METHODS

We measured total platinum concentrations by flameless atomic absorption spectrophotometry in 44 archived fresh-frozen NSCLC specimens from patients who underwent surgical resection after neoadjuvant platinum-based chemotherapy. Tissue platinum concentration was correlated with percent reduction in tumor size on post- versus prechemotherapy computed tomography scans. The relationship between tissue platinum concentration and survival was assessed by univariate and multicovariate Cox proportional hazards regression model analysis and Kaplan-Meier analysis.

RESULTS

Tissue platinum concentration correlated significantly with percent reduction in tumor size (P < .001). The same correlations were seen with cisplatin, carboplatin, and all histology subgroups. Furthermore, there was no significant impact of potential variables such as number of cycles and time lapse from last chemotherapy on platinum concentration. Patients with higher platinum concentration had longer time to recurrence (P = .034), progression-free survival (P = .018), and overall survival (P = .005) in the multicovariate Cox model analysis after adjusting for number of cycles.

CONCLUSION

This clinical study established a relationship between tissue platinum concentration and response in NSCLC. It suggests that reduced platinum accumulation might be an important mechanism of platinum resistance in the clinical setting. Further studies investigating factors that modulate intracellular platinum concentration are warranted.

Non-small cell lung cancer: the era of targeted therapy

In this review, the authors aim to provide an overview of current molecular targeted therapies for NSCLC, to propose an algorithm for clinical application of presently available treatment strategies, and to identify future directions for this important area of research. Historically, choice of treatment algorithm for the management of non-small cell lung cancer (NSCLC) has relied heavily upon histology and clinical staging information, typically assigning patients to surgery, chemotherapy, radiation, or a combination thereof. However, previous treatment strategies have been fraught with disappointing response rates and significant systemic toxicities. The concept of personalized therapy for NSCLC involves characterization of each individual patient's tumor, in terms of genetic aberrations and expected biologic behavior, and using this information to tailor subsequent clinical management. Several driver mutations have been identified to date in subsets of patients with NSCLC, and, by focusing on specific molecular targets, new agents have been developed with the intent of treating the cancer cells while causing minimal toxicity to benign, healthy cells. In particular, current strategies exist to identify patients with epidermal growth factor receptor gene mutations and anaplastic lymphoma kinase rearrangements, with promising results upon clinical application of agents targeting these abnormalities. Moving forward, attempts are being made to determine comprehensive genetic and biologic characterization of individuals' NSCLC tumors and to incorporate these findings into everyday practice. The era of targeted therapy is upon us. As we seek to expand our knowledge of the specific molecular and cellular derangements leading to growth and proliferation of NSCLC tumors, our efforts bring us closer to ultimately providing each patient with a personalized plan of care.

Ganoderma tsugae Induces S Phase Arrest and Apoptosis in Doxorubicin-Resistant Lung Adenocarcinoma H23/0.3 Cells via Modulation of the PI3K/Akt Signaling Pathway

Ganoderma tsugae (GT) is a traditional Chinese medicine that exhibits significant antitumor activities against many types of cancer. This study investigated the molecular mechanism by which GT suppresses the growth of doxorubicin-resistant lung adenocarcinoma H23/0.3 cells. Our results reveal that GT inhibits the viability of H23/0.3 cells in vitro and in vivo and sensitizes the growth suppression effect of doxorubicin on H23/0.3 cells. The data also show that GT induces S phase arrest by interfering with the protein expression of cyclin A, cyclin E, CDK2, and CDC25A. Furthermore, GT induces cellular apoptosis via induction of a mitochondria/caspase pathway. In addition, we also demonstrate that the suppression of cell proliferation by GT is through down-regulation of the PI3K/Akt signaling pathway. In conclusion, this study suggests that GT may be a useful adjuvant therapeutic agent in the treatment of lung cancer.

In vivo selection of autologous MGMT gene-modified cells following reduced-intensity conditioning with BCNU and temozolomide in the dog model

Chemotherapy with 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) and temozolomide (TMZ) is commonly used for the treatment of glioblastoma multiforme (GBM) and other cancers. In preparation for a clinical gene therapy study in patients with glioblastoma, we wished to study whether these reagents could be used as a reduced-intensity conditioning regimen for autologous transplantation of gene-modified cells. We used an MGMT(P140K)-expressing lentivirus vector to modify dog CD34(+) cells and tested in four dogs whether these autologous cells engraft and provide chemoprotection after transplantation. Treatment with O(6)-benzylguanine (O6BG)/TMZ after transplantation resulted in gene marking levels up to 75%, without significant hematopoietic cytopenia, which is consistent with hematopoietic chemoprotection. Retrovirus integration analysis showed that multiple clones contribute to hematopoiesis. These studies demonstrate the ability to achieve stable engraftment of MGMT(P140K)-modified autologous hematopoietic stem cells (HSCs) after a novel reduced-intensity conditioning protocol using a combination of BCNU and TMZ. Furthermore, we show that MGMT(P140K)-HSC engraftment provides chemoprotection during TMZ dose escalation. Clinically, chemoconditioning with BCNU and TMZ should facilitate engraftment of MGMT(P140K)-modified cells while providing antitumor activity for patients with poor prognosis glioblastoma or alkylating agent-sensitive tumors, thereby supporting dose-intensified chemotherapy regimens.

Targeting MDR in breast and lung cancer: discriminating its potential importance from the failure of drug resistance reversal studies

This special issue of Drug Resistance Updates is dedicated to multidrug resistance protein 1 (MDR-1), 35 years after its discovery. While enormous progress has been made and our understanding of drug resistance has become more sophisticated and nuanced, after 35 years the role of MDR-1 in clinical oncology remains a work in progress. Despite clear in vitro evidence that P-glycoprotein (Pgp), encoded by MDR-1, is able to dramatically reduce drug concentrations in cultured cells, and that drug accumulation can be increased by small molecule inhibitors, clinical trials testing this paradigm have mostly failed. Some have argued that it is no longer worthy of study. However, repeated analyses have demonstrated MDR-1 expression in a tumor is a poor prognostic indicator leading some to conclude MDR-1 is a marker of a more aggressive phenotype, rather than a mechanism of drug resistance. In this review we will re-evaluate the MDR-1 story in light of our new understanding of molecular targeted therapy, using breast and lung cancer as examples. In the end we will reconcile the data available and the knowledge gained in support of a thesis that we understand far more than we realize, and that we can use this knowledge to improve future therapies.

Single nucleotide polymorphisms as susceptibility, prognostic, and therapeutic markers of nonsmall cell lung cancer

Lung cancer is a major public health problem throughout the world. Among the most frequent cancer types (prostate, breast, colorectal, stomach, lung), lung cancer is the leading cause of cancer-related deaths worldwide. Among the two major subtypes of small cell lung cancer and nonsmall cell lung cancer (NSCLC), 85% of tumors belong to the NSCLC histological types. Small cell lung cancer is associated with the shortest survival time. Although tobacco smoking has been recognized as the major risk factor for lung cancer, there is a great interindividual and interethnic difference in risk of developing lung cancer given exposure to similar environmental and lifestyle factors. This may indicate that in addition to chemical and environmental factors, genetic variations in the genome may contribute to risk modification. A common type of genetic variation in the genome, known as single nucleotide polymorphism, has been found to be associated with susceptibility to lung cancer. Interestingly, many of these polymorphisms are found in the genes that regulate major pathways of carcinogen metabolism (cytochrome P450 genes), detoxification (glutathione S-transferases), adduct removal (DNA repair genes), cell growth/apoptosis (TP53/MDM2), the immune system (cytokines/chemokines), and membrane receptors (nicotinic acetylcholine and dopaminergic receptors). Some of these polymorphisms have been shown to alter the level of mRNA, and protein structure and function. In addition to being susceptibility markers, several of these polymorphisms are emerging to be important for response to chemotherapy/radiotherapy and survival of patients. Therefore, it is hypothesized that single nucleotide polymorphisms will be valuable genetic markers in individual-based prognosis and therapy in future. Here we will review some of the most important single nucleotide polymorphisms in the metabolic pathways that may modulate susceptibility, prognosis, and therapy in NSCLC.

Modeling the transcriptional consequences of epidermal growth factor receptor ablation in Ras-initiated squamous cancer

PURPOSE

Epidermal growth factor receptor (EGFR)-targeted therapy is in clinical use to treat squamous cell carcinoma of the head and neck and other cancers of lining epithelium. RAS mutations in these tumors are a negative prognostic factor for response, and skin inflammation is an adverse reaction to therapy. We investigated transcriptional and biochemical changes that could account for the confounding effects of RAS activation and inflammation in a squamous tissue.

EXPERIMENTAL DESIGN

We carried out gene expression profiling on oncogenic Ras-transformed and wild-type mouse and human keratinocytes with EGFR ablated chronically by genetic deletion or acutely by drug treatment and followed leads provided by pathway analysis with biochemical studies.

RESULTS

We identified a 25-gene signature specific to the Ras-EGFR ablation interaction and a distinct 19-gene EGFR ablation signature on normal keratinocytes. EGFR ablation in the context of wild-type Ras reduces ontologies favoring cell-cycle control and transcription, whereas oncogenic Ras enriches ontologies for ion channels and membrane transporters, particularly focused on calcium homeostasis. Ontologies between chronic EGFR ablation and acute pharmacologic ablation were unique, both with and without Ras activation. p38α is activated in response to abrogation of EGFR signaling under conditions of Ras activation in both mouse and human keratinocytes and in RAS-transformed tumor orthografts of EGFR-ablated mouse keratinocytes. EGFR ablation in the absence of oncogenic Ras revealed Erk and interleukin-1β-related pathways.

CONCLUSION

These findings reveal unrecognized interactions between Ras and EGFR signaling in squamous tumor cells that could influence the therapeutic response to EGFR ablation therapy.

DNA repair capacity in peripheral lymphocytes predicts survival of patients with non-small-cell lung cancer treated with first-line platinum-based chemotherapy

PURPOSE

Platinum-based regimens are the standard chemotherapy for patients with advanced non-small-cell lung cancer (NSCLC). DNA repair capacity (DRC) in tumor cells plays an important role in resistance to platinum-based drugs. We have previously reported that efficient DRC, as assessed by an in vitro lymphocyte-based assay, was a determinant of poor survival in patients with NSCLC in a relatively small data set. In this larger independent study of 591 patients with NSCLC, we further evaluated whether DRC in peripheral lymphocytes predicts survival of patients with NSCLC who receive platinum-based chemotherapy.

PATIENTS AND METHODS

All patients were recruited at The University of Texas MD Anderson Cancer Center and donated blood samples before the start of any chemotherapy. We measured DRC in cultured T lymphocytes by using the host-cell reactivation assay, and we assessed associations between DRC in peripheral lymphocytes and survival of patients with NSCLC who were treated with first-line platinum-based chemotherapy.

RESULTS

We found an inverse association between DRC in peripheral lymphocytes and patient survival. Compared with patients in the low tertile of DRC, patients with NSCLC in the high tertile of DRC had significantly worse overall and 3-year survival (adjusted hazard ratio [HR], 1.33; 95% CI, 1.04 to 1.71; P = .023; and HR, 1.35; 95% CI, 1.04 to 1.76; P = .025, respectively). This trend was more pronounced in patients with early-stage tumors, adenocarcinoma, or squamous cell carcinoma.

CONCLUSION

We confirmed that DRC in peripheral lymphocytes is an independent predictor of survival for patients with NSCLC treated with platinum-based chemotherapy.

Dysfunction of volume-sensitive chloride channels contributes to cisplatin resistance in human lung adenocarcinoma cells

Cisplatin-based chemotherapy is the standard therapy used to treat non-small-cell lung cancer. However, its efficacy is largely limited due to the development of drug resistance. The exact mechanism in which cancer cells develop resistance to the drug is not yet fully understood. The purpose of the present study is to test the role of volume-sensitive Cl(-) channels in cisplatin resistance in human lung adenocarcinoma cells (A549 cells) using patch-clamp recording, cell volume measurement and apoptosis assay. The results showed that cisplatin treatment induced an apoptotic volume decrease (AVD) and activated a Cl(-) current that showed properties similar to the volume-sensitive outward rectifying (VSOR) Cl(-) current in wild-type A549 cells. Both the AVD process and VSOR Cl(-) current were blocked by the chloride channel blocker 4,4'-diisothiocyanostilbene-2,2' disulfonic acid. However, the A549/CDDP cells, a model of acquired cisplatin resistance cells, on the other hand, had almost no AVD process and VSOR Cl(-) current when treated with cisplatin. Treatment of A549/CDDP cells with trichostatin A (TSA), a drug that inhibits histone deacetylases, partially restored the VSOR Cl(-) current and increased cisplatin-induced cell apoptosis rate. These results suggest that impaired activity of VSOR Cl(-) channels contributes to the cisplatin resistance in A549/CDDP cells.

Predictive value of multidrug resistance proteins, topoisomerases II and ERCC1 in small cell lung cancer: a systematic review

In small-cell lung cancer (SCLC), resistance to cancer drugs presents a major problem, limiting the effectiveness of chemotherapy. A better understanding of the molecular biology is essential to improve currently available cytotoxic therapy. Herein, a systematic review of studies evaluating the predictive value of multidrug resistance-associated proteins (MDR1, MRP1, MRP2 and MVP), topoisomerase II and ERCC1 for chemotherapy outcomes is presented. The role of MDR1, MRP1 and MRP2 as predictive markers in SCLC has not yet been elucidated. The majority of studies reported an association between protein or gene expression and response to chemotherapy; however, the evidence is limited to univariate analyses performed in the frame of small retrospective trials. In addition, the largest trial did not confirm an independent predictive value for response rates or survival. Genetic variability may be overseen as a more promising marker. Available data on the predictive value of topoisomerase II are scarce and in contrast to the general idea that higher protein or gene expression correlate with greater chemo-sensitivity. The data on a possible predictive value of ERCC1 are also quite limited; in two retrospective studies, ERCC1 turned out to be a significant predictive marker for survival, but only for limited disease patients. In conclusion, a continuous research, with standardized and validated methodology of markers' determination, should be aspired at all times; a better understanding of the biology of SCLC is of utmost importance to enable personalized therapy and to improve survival rates in this, so far, poorly controlled disease.

Extensive disease small cell lung cancer dose-response relationships: implications for resistance mechanisms

BACKGROUND

Some studies (but not others) suggested that high doses are beneficial in small cell lung cancer (SCLC). We hypothesized that dose-response curve (DRC) shape reflects resistance mechanisms.

METHODS

We reviewed published SCLC clinical trials and converted response rates into estimated mean tumor cell kill, assuming killing is proportional to reduction in tumor volume. Mean % cell survival was plotted versus planned dose intensity. Nonlinear and linear meta-regression analyses (weighted according to the number of patients in each study) were used to assess DRC characteristics.

RESULTS

Although associations between dose and cell survival were not statistically significant, DRCs sloped downward for five of seven agents across all doses and for all seven when lowest doses were excluded. Maximum mean cell kill across all drugs and doses was approximately 90%, suggesting that there may be a maximum achievable tumor cell kill irrespective of number of agents or drug doses.

CONCLUSIONS

Downward DRC slopes suggest that maintaining relatively high doses may possibly maximize palliation, although the associations between dose and slope did not achieve statistical significance, and slopes for most drugs tended to be shallow. DRC flattening at higher doses would preclude cure and would suggest that "saturable passive resistance" (deficiency of factors required for cell killing) limits maximum achievable cell kill. An example of factors that could flatten the DRC at higher doses and lead to saturable passive resistance would be presence of quiescent, noncycling cells.

A pharmacodynamic study of docetaxel in combination with the P-glycoprotein antagonist tariquidar (XR9576) in patients with lung, ovarian, and cervical cancer

PURPOSE

P-glycoprotein (Pgp) antagonists have been difficult to develop because of complex pharmacokinetic interactions and a failure to show meaningful results. Here we report the results of a pharmacokinetic and pharmacodynamic trial using a third-generation, potent, noncompetitive inhibitor of Pgp, tariquidar (XR9576), in combination with docetaxel.

EXPERIMENTAL DESIGN

In the first treatment cycle, the pharmacokinetics of docetaxel (40 mg/m(2)) were evaluated after day 1 and day 8 doses, which were administered with or without tariquidar (150 mg). (99m)Tc-sestamibi scanning and CD56(+) mononuclear cell rhodamine efflux assays were conducted to assess Pgp inhibition. In subsequent cycles, 75 mg/m(2) docetaxel was administered with 150 mg tariquidar every 3 weeks.

RESULTS

Forty-eight patients were enrolled onto the trial. Nonhematologic grade 3/4 toxicities in 235 cycles were minimal. Tariquidar inhibited Pgp-mediated rhodamine efflux from CD56(+) cells and reduced (99m)Tc-sestamibi clearance from the liver. There was striking variability in basal sestamibi uptake; a 12% to 24% increase in visible lesions was noted in 8 of 10 patients with lung cancer. No significant difference in docetaxel disposition was observed in pairwise comparison with and without tariquidar. Four partial responses (PR) were seen (4/48); 3 in the non-small cell lung cancer (NSCLC) cohort, measuring 40%, 57%, and 67% by RECIST, and 1 PR in a patient with ovarian cancer.

CONCLUSIONS

Tariquidar is well tolerated, with less observed systemic pharmacokinetic interaction than previous Pgp antagonists. Variable effects of tariquidar on retention of sestamibi in imageable lung cancers suggest that follow-up studies assessing tumor drug uptake in this patient population would be worthwhile.