Immunohistochemical detection of DNA topoisomerase IIalpha, P-glycoprotein and multidrug resistance protein (MRP) in small-cell and non-small-cell lung cancer

Inter‑component immunohistochemical assessment of proliferative markers in uterine carcinosarcoma

In the scientific literature, a selected number of reports have investigated the impact of proliferative activity on the development and progression of uterine carcinosarcomas (UC). The aim of the present retrospective study was to compare the immunohistochemical proliferation markers [Ki67, proliferating cell nuclear antigen (PCNA), minichromosome maintenance complex component 3 (MCM3), and topoisomerase IIα (topoIIα)] assessment in both components of UC. A total of 30 paraffin-embedded slides of UCs, obtained from patients who underwent surgery between January 1, 2006, and December 31, 2020, were analyzed. Medical records and clinicopathological data of patients were reviewed. Formalin-fixed, paraffin-embedded tissue sections were immunostained with monoclonal antibodies against Ki67, PCNA, MCM3 and topoIIα. Ki67-positive nuclear immunoreactivity was reported in 20 (67%) and 16 (53%) UC carcinomatous and sarcomatous components, respectively. In the epithelial component, Ki67 positive staining was related to the International Federation of Gynecology and Obstetrics (FIGO) stage (P=0.025), and histological grade (G1 vs. G2/G3, P=0.031). Nuclear PCNA reactivity was observed in 18 (60%) and 16 (53%) carcinomatous and sarcomatous components, respectively. Notably, all four cases with omental metastases were PCNA-positive, and a relationship between staining pattern and the existence of metastases was of significant value (P=0.018). MCM3-positive nuclear staining was found nearly twice as high in the carcinomatous (n=19; 63%), compared with the sarcomatous (n=11; 37%) component, respectively, and MCM3 expression in the epithelial component was related to clinical stage (P=0.030), and the existence of omental metastasis (P=0.012). In addition, out of the 30 UCs, 17 (57%) and 13 (43%) showed topoIIα positivity in the carcinomatous and sarcomatous UC components, respectively. A significant relationship between protein immunoreactivity and FIGO stage (P=0.049), and omental metastasis (P=0.026) was revealed to exist. However, no significant differences between expression of proliferation markers and clinicopathological features in the sarcomatous UC component were identified. Finally, a significant correlation between each protein immunohistochemical staining was demonstrated, particularly in the sarcomatous UC component. Collectively, a combined analysis of Ki67, PCNA, MCM3, and topoIIα may provide more detailed information of cell-cycle alterations determining the heterogeneity of uterine carcinosarcomas.

Targeting multidrug resistance-associated protein 1 (MRP1)-expressing cancers: Beyond pharmacological inhibition

Resistance to chemotherapy remains one of the most significant obstacles to successful cancer treatment. While inhibiting drug efflux mediated by ATP-binding cassette (ABC) transporters is a seemingly attractive and logical approach to combat multidrug resistance (MDR), small molecule inhibition of ABC transporters has so far failed to confer clinical benefit, despite considerable efforts by medicinal chemists, biologists, and clinicians. The long-sought treatment to eradicate cancers displaying ABC transporter overexpression may therefore lie within alternative targeting strategies. When aberrantly expressed, the ABC transporter multidrug resistance-associated protein 1 (MRP1, ABCC1) confers MDR, but can also shift cellular redox balance, leaving the cell vulnerable to select agents. Here, we explore the physiological roles of MRP1, the rational for targeting this transporter in cancer, the development of small molecule MRP1 inhibitors, and the most recent developments in alternative therapeutic approaches for targeting cancers with MRP1 overexpression. We discuss approaches that extend beyond simple MRP1 inhibition by exploiting the collateral sensitivity to glutathione depletion and ferroptosis, the rationale for targeting the shared transcriptional regulators of both MRP1 and glutathione biosynthesis, advances in gene silencing, and new molecules that modulate transporter activity to the detriment of the cancer cell. These strategies illustrate promising new approaches to address multidrug resistant disease that extend beyond the simple reversal of MDR and offer exciting routes for further research.

Clinical significance of topoisomerase-II expression in patients with advanced non-small cell lung cancer treated with amrubicin

Background

Amrubicin chemotherapy is a treatment option for patients with non‐small cell lung cancer (NSCLC) after third‐line treatment in Japan. Although topoisomerase‐II (Topo‐II), a target of amrubicin, has been reported to be a prognostic or predictive marker for chemosensitivity and clinical outcomes in various types of malignancies, its effects in the Japanese population remain unknown.

Methods

Data regarding 44 patients with advanced NSCLC treated with amrubicin between April 2004 and May 2014 were retrospectively analyzed. We evaluated the expression levels of Topo‐II by immunohistochemical staining of tumor specimens obtained via biopsy or surgical resection.

Results

The majority of enrolled patients were men (68%) with a median age of 67 (range, 43–78) years. The most common histological type was adenocarcinoma (70%). High Topo‐II expression was observed in 13 (30%) of the 44 patients. The median progression‐free survival and overall survival (OS) durations were 1.8 and 8.8 months, respectively. While there was no significant association between Topo‐II expression and progression‐free survival, patients with low Topo‐II expression had significantly longer OS than did those with high Topo‐II expression. Good performance status and low expression of Topo‐II were all significantly associated with a favorable OS.

Conclusion

Low expression of Topo‐II was identified as an independent prognostic factor for longer survival in patients with NSCLC receiving amrubicin, a Topo‐II inhibitor.

Key points

Chemotherapy Resistance in Lung Cancer

Despite a growing interest in development of non-cytotoxic targeted agents, systemic chemotherapy is still the mainstay of treatment for both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). However, chemotherapy resistance limits our ability to effectively treat advanced lung cancer. Some lung tumors are intrinsically resistant to chemotherapy, and in virtually all cases, even the initial responders rapidly develop acquired resistance. While targeting histology could result in enhanced tumor sensitivity to a particular chemotherapeutic agent, better understanding of molecular determinants of chemotherapy sensitivity/resistance would be critically important. Development of predictive biomarkers to personalize chemotherapeutic agents and combining novel agents targeting specific resistance pathways with standard chemotherapy could be some promising strategies to overcome chemotherapy resistance in lung cancer. In this chapter, we will discuss some key mechanisms of resistance for commonly used chemotherapeutic agents in lung cancer.

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.

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.

Placental isoform glutathione S-transferase and P-glycoprotein expression in advanced nonsmall cell lung cancer: association with response to treatment and survival

BACKGROUND

Increased expression of the glutathione S-transferase placental isoform (GST-pi) and of P-glycoprotein (P-gp) in tissues from patients with nonsmall cell lung cancer (NSCLC) has been associated with poor antineoplastic drug sensitivity, response to treatment, and survival. However, the diagnosis of advanced NSCLC often is based on cytology. The objectives of the current study were to examine GST-pi and P-gp expression in cytologic specimens from patients with unresectable NSCLC and to determine the association of that expression with response to chemotherapy and survival.

METHODS

Patients with unresectable, cytologically diagnosed NSCLC were eligible for the study. Diagnosis was made by fiberoptic bronchoscopy, and staging was done according to international standards. All patients received sequential chemoradiotherapy and were re-evaluated for treatment response. GST-pi and P-gp expression levels were evaluated by immunocytochemistry and immunohistochemistry of bronchial brushing/washing and bronchial tissue biopsy, respectively. Survival was defined as the time between diagnosis and death or last follow-up at 24 months.

RESULTS

Thirty-nine patients were included in the study. There were 35 men and 4 women, and the mean patient age (+/-standard deviation was 61.4 years (+/-9.1 years). There were 4 patients with stage IIIA NSCLC, 32 patients with stage IIIB NSCLC, and 3 patients with stage IV NSCLC. Cytologic evaluation of GST-pi and P-gp expression paralleled expression determined in pathology specimens. GST-pi and P-gp expression levels were associated inversely with response to chemotherapy and survival.

CONCLUSIONS

Cytologic evaluation of GST-pi and P-gp expression may predictor the response to treatment and the survival of patients with advanced NSCLC.

Portrait of multifaceted transporter, the multidrug resistance-associated protein 1 (MRP1/ABCC1)

MRP1 (ABCC1) is a peculiar member of the ABC transporter superfamily for several aspects. This protein has an unusually broad substrate specificity and is capable of transporting not only a wide variety of neutral hydrophobic compounds, like the MDR1/P-glycoprotein, but also facilitating the extrusion of numerous glutathione, glucuronate, and sulfate conjugates. The transport mechanism of MRP1 is also complex; a composite substrate-binding site permits both cooperativity and competition between various substrates. This versatility and the ubiquitous tissue distribution make this transporter suitable for contributing to various physiological functions, including defense against xenobiotics and endogenous toxic metabolites, leukotriene-mediated inflammatory responses, as well as protection from the toxic effect of oxidative stress. In this paper, we give an overview of the considerable amount of knowledge which has accumulated since the discovery of MRP1 in 1992. We place special emphasis on the structural features essential for function, our recent understanding of the transport mechanism, and the numerous assignments of this transporter.

Transmembrane transport of endo- and xenobiotics by mammalian ATP-binding cassette multidrug resistance proteins

Multidrug Resistance Proteins (MRPs), together with the cystic fibrosis conductance regulator (CFTR/ABCC7) and the sulfonylurea receptors (SUR1/ABCC8 and SUR2/ABCC9) comprise the 13 members of the human "C" branch of the ATP binding cassette (ABC) superfamily. All C branch proteins share conserved structural features in their nucleotide binding domains (NBDs) that distinguish them from other ABC proteins. The MRPs can be further divided into two subfamilies "long" (MRP1, -2, -3, -6, and -7) and "short" (MRP4, -5, -8, -9, and -10). The short MRPs have a typical ABC transporter structure with two polytropic membrane spanning domains (MSDs) and two NBDs, while the long MRPs have an additional NH2-terminal MSD. In vitro, the MRPs can collectively confer resistance to natural product drugs and their conjugated metabolites, platinum compounds, folate antimetabolites, nucleoside and nucleotide analogs, arsenical and antimonial oxyanions, peptide-based agents, and, under certain circumstances, alkylating agents. The MRPs are also primary active transporters of other structurally diverse compounds, including glutathione, glucuronide, and sulfate conjugates of a large number of xeno- and endobiotics. In vivo, several MRPs are major contributors to the distribution and elimination of a wide range of both anticancer and non-anticancer drugs and metabolites. In this review, we describe what is known of the structure of the MRPs and the mechanisms by which they recognize and transport their diverse substrates. We also summarize knowledge of their possible physiological functions and evidence that they may be involved in the clinical drug resistance of various forms of cancer.

[Expression of multidrug resistance (MDR)-associated proteins in solid tumors]

The causes of drug resistance in tumor cells vary widely. The present study aims to provide an update of multidrug resistance in tumor cells and, in particular, of multidrug resistance-associated proteins.

Comparison of chemotherapy response with P-glycoprotein, multidrug resistance-related protein-1, and lung resistance-related protein expression in untreated small cell lung cancer

The aim of this study was to investigate the expression of P-glycoprotein (Pgp), multidrug resistance-related protein-1 (MRP1), and lung resistance-related protein (LRP) in response to chemotherapy in untreated small cell lung cancer (SCLC). Immunohistochemical analyses were performed on multiple nonconsecutive sections of biopsy specimens to detect Pgp, MRP1, and LRP expression in 40 patients with SCLC before chemotherapeutic induction. Response to chemotherapy was evaluated by clinical and radiological methods. The patients were divided into a good response group (n = 20) and a poor response group (n = 20). No significant differences in prognostic factors (Karnofsky performance status, tumor size, or tumor stage) were found between the two groups of patients. The difference in positive Pgp and MRP1 expressions between the good and poor response groups was significant. However, the difference in LRP expression was not significant. We conclude that chemotherapy response of patients with SCLC was related to either Pgp or MRP1 but not LPR expression.

To predict response chemotherapy using technetium-99m tetrofosmin chest images in patients with untreated small cell lung cancer and compare with p-glycoprotein, multidrug resistance related protein-1, and lung resistance-related protein expression

Our preliminary studies found technetium-99m tetrofosmin (Tc- TF) chest imaging was related to Pgp or MRP1 expression and successfully predict chemotherapy response and in SCLC in human. However, there was no published literature to study relationship of Tc-TF chest images and LRP expression in SCLC patients. Therefore, the aim of this study was to investigate the relationships among Tc- TF accumulation in untreated small cell lung cancer (SCLC), the expression of P-glycoprotein (Pgp), multidrug resistance related protein-1 (MRP1), and lung resistance-related protein (LRP), as well as the response to chemotherapy in patients with untreated SCLC. Thirty patients with SCLC were studied with chest images 15 to 30 minutes after intravenous injection of Tc-TF before chemotherapeutic induction. Tumor-to-background (T/B) ratios were obtained on the static and plantar Tc-TF chest images. The response to chemotherapy was evaluated upon completion of chemotherapy by clinical and radiological methods. These patients were separated into 15 patients with good response and 15 patients with poor response. No significant differences of prognostic factors (Karnofsky performance status, tumor size, or tumor stage) were found between the patients with good and poor responses. Immunohistochemical analyses were performed on multiple nonconsecutive sections of biopsy specimens to detect Pgp, MRP1, and LRP expression. The difference in T/B ratios on the Tc-TF chest images of the patients with good versus poor response was significant. The differences in T/B ratios of the patients with positive versus negative Pgp expression and with positive versus negative MRP1 expression were significant. The difference in T/B ratios of the patients with positive versus negative LRP expression was not significant. We concluded that Tc-TF chest images could accurately predict chemotherapy response of patients with SCLC. In addition, The Tc-TF tumor uptake was related to Pgp or MRP1 but not LPR expression in SCLC.

Pharmacogenetics of anticancer drug sensitivity in non-small cell lung cancer

In mammalian cells, the process of malignant transformation is characterized by the loss or down-regulation of tumor-suppressor genes and/or the mutation or overexpression of proto-oncogenes, whose products promote dysregulated proliferation of cells and extend their life span. Deregulation in intracellular transduction pathways generates mitogenic signals that promote abnormal cell growth and the acquisition of an undifferentiated phenotype. Genetic abnormalities in cancer have been widely studied to identify those factors predictive of tumor progression, survival, and response to chemotherapeutic agents. Pharmacogenetics has been founded as a science to examine the genetic basis of interindividual variation in drug metabolism, drug targets, and transporters, which result in differences in the efficacy and safety of many therapeutic agents. The traditional pharmacogenetic approach relies on studying sequence variations in candidate genes suspected of affecting drug response. However, these studies have yielded contradictory results because of the small number of molecular determinants of drug response examined, and in several cases this approach was revealed to be reductionistic. This limitation is now being overcome by the use of novel techniques, i.e., high-density DNA and protein arrays, which allow genome- and proteome-wide tumor profiling. Pharmacogenomics represents the natural evolution of pharmacogenetics since it addresses, on a genome-wide basis, the effect of the sum of genetic variants on drug responses of individuals. Development of pharmacogenomics as a new field has accelerated the progress in drug discovery by the identification of novel therapeutic targets by expression profiling at the genomic or proteomic levels. In addition to this, pharmacogenetics and pharmacogenomics provide an important opportunity to select patients who may benefit from the administration of specific agents that best match the genetic profile of the disease, thus allowing maximum activity.

Size and P-glycoprotein expression limit 99mTc-tetrofosmin uptake in parathyroid adenomas

The purpose of this study was to retrospectively evaluate (99m)Tc-tetrofosmin (Tc-TF) uptake in large parathyroid adenomas and to compare the results with their expression of multidrug resistance (MDR)-mediated, 170 kDa, P-glycoprotein (Pgp). Twenty patients with large parathyroid adenomas (larger than 1.5 g), who had undergone early and delayed (10 min and 2 h) Tc-TF parathyroid imaging before operation, were enrolled in this retrospective study. Immunohistochemical analyses were performed on multiple, non-consecutive sections of the 20 parathyroid adenomas and 40 normal control specimens (20 normal parathyroid glands and 16 normal thyroid specimens) to detect Pgp expression. Tc-TF parathyroid imaging accurately localized 17 large parathyroid adenomas, but not the remaining three. The 17 parathyroid adenomas with significant Tc-TF uptake in delayed (2 h) parathyroid images revealed negative Pgp expression, but the three adenomas without significant Tc-TF uptake, as well as 20 normal parathyroid glands and 20 normal thyroid specimens, revealed positive Pgp expression. Therefore, not only the size, but also the expression of Pgp, limited the sensitivity of Tc-TF parathyroid imaging to localize parathyroid adenomas before operation.

Using technetium 99m tetrofosmin parathyroid imaging to detect parathyroid adenoma and its relation to P-glycoprotein expression

BACKGROUND

The purpose of this study was to retrospectively evaluate technetium 99m tetrofosmin (Tc-TF) uptake in parathyroid adenomas and compare the results with their expression of multidrug resistance-mediated 170-kDa P-glycoprotein (Pgp).

METHODS

Twenty patients with larger parathyroid adenomas (> 1.5 g) and the other 40 patients with smaller parathyroid adenomas (0.5-1.5 g) underwent early and delayed (10-minute and 2-hour) Tc-TF parathyroid imaging before operation. In this retrospective study, immunohistochemical analyses were performed on multiple nonconsecutive sections of the 40 parathyroid adenomas and 40 normal control specimens (20 normal parathyroid glands and 20 normal thyroid specimens) to detect Pgp expression.

RESULTS

The Tc-TF parathyroid image accurately localized 17 larger and 16 smaller parathyroid adenomas, but not the remaining 3 larger and 4 smaller adenomas. The 17 larger and 16 smaller parathyroid adenomas with significant Tc-TF uptake on the delayed 2-hour parathyroid images revealed negative Pgp expression, but the 3 larger and 4 smaller adenomas without significant Tc-TF uptake, as well as 20 normal parathyroid glands and 20 normal thyroid specimens, revealed positive Pgp expression.

CONCLUSIONS

Not only the size of parathyroid adenomas, but Pgp expression also limited the sensitivity of Tc-TF parathyroid image to localize parathyroid adenomas before the operation.

Detecting parathyroid adenoma using technetium-99m tetrofosmin: comparison with P-glycoprotein and multidrug resistance related protein expression--a preliminary report

The aim of this study was to investigate the relationships among technetium-99m tetrofosmin (Tc-TF) accumulation in parathyroid adenoma and the expression of P-glycoprotein (Pgp) or multidrug resistance related protein (MRP). Before operation, 33 patients with parathyroid adenomas (larger than 1.5 gm) were studied with parathyroid scintigraphy 10 minutes and 2 hours after intravenous injection of Tc-TF before operation. Immunohistochemical analyses (IHA) were performed on multiple nonconsecutive sections of operative parathyroid specimens to detect Pgp or MRP expression. According to the results of IHA, the 33 parathyroid adenomas were separated into four groups: (1) 2 adenomas with both positive Pgp and positive MRP expression, (2) 1 adenomas with positive Pgp but negative MRP expression, (3) 2 adenomas with negative Pgp but positive MRP expression, and (4) 28 adenomas with both negative Pgp and negative MRP expression. All of 28 adenomas in the group 4 could be detected by Tc-TF parathyroid imaging. All of 5 adenomas in the groups 1 to 3 could not be detected by TcTF parathyroid imaging (p < 0.05). Not only the size of parathyroid adenomas, but also significant Pgp or MRP expression limited the sensitivity of Tc-TF parathyroid imaging to localize parathyroid adenomas before operation.

Correlation between P-glycoprotein (P-gp) expression in parathyroid and Tc-99m MIBI parathyroid image findings

The major factor to influence localization of parathyroid adenomas is tumor size. P-glycoprotein (P-gp) expression in parathyroid adenomas has been considered to be an another possible factor to influence localization of parathyroid adenomas because false-negative studies have been reported with large tumors and true-positives reported with very small tumors in previous studies. The aim of this study was to characterize Tc-99m MIBI uptake and retention by parathyroid adenomas and to correlate this with cell surface expression of P-gp. Sixteen patients with parathyroid adenoma (larger than 1.5 gm) underwent dual-phase (10min and 2hr) Tc-99m MIBI parathyroid image immediately before parathyroid exploration. Tissues were obtained from normal and abnormal parathyroid glands and from the thyroid gland. Immunohistochemistry (IHC) was obtained with monoclonal antibodies to identify P-gp expression in all tissues. All of the 16 parathyroid adenomas and 32 normal control specimens (16 normal parathyroid and 16 normal thyroid specimens) were submitted for P-gp detection by IHC. The dual-phase Tc-99m MIBI parathyroid image accurately localized 14 parathyroid adenomas, but not the remaining 2 adenomas. The 14 parathyroid adenomas with significant Tc-99m MIBI uptake in delayed 2hr images revealed negative P-gp expression, but the 2 adenomas without significant Tc-99m MIBI uptake, as well as normal parathyroid and normal thyroid specimens, revealed positive P-gp expression when evaluated by IHC. Not only the size of parathyroid adenomas, but also significant P-gp expression limited the sensitivity of dual-phase Tc-99m MIBI parathyroid image to localize parathyroid adenomas before operation.

Technetium-99m methoxyisobutylisonitrile chest imaging for small-cell lung cancer. Relationship to chemotherapy response (six courses of combination of cisplatin and etoposide) and p-glycoprotein or multidrug resistance related protein expression

AIMS

This is a retrospective and adaptive randomization study. The purpose of this study was to evaluate the relationship between technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) chest-imaging results, chemotherapy response and P-glycoprotein (Pgp) or multidrug resistance related protein (MRP) expression in small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Before chemotherapy, 30 patients (11 females, 19 males, ages: 52-69 years) with SCLC, including 14 extensive diseases without localized problems and 16 limited diseases in excess of solitary pulmonary nodule, underwent early chest imaging, including visual interpretation and quantitative analyses of tumor uptake ratio (TUR), 10 minutes after intravenous injection of Tc-99m MIBI. Immunohistochemical analyses were performed, using multiple nonconsecutive sections of the biopsy specimens, to detect Pgp and MRP expressions. Chemotherapy response was evaluated in the third month after completion of treatment by clinical and radiological methods.

RESULTS

All 15 (100%) of the SCLC patients with complete or partial response had positive Tc-99m MIBI chest SPECT results, but negative ones for both Pgp and MRP expression. Twelve of the 15 (80%) SCLC patients with no response or progressive disease had negative Tc-99m MIBI chest SPECT results and were positive for either Pgp or MRP expression (P < 0.05). Negative Tc-99m MIBI chest SPECT results predicted complete or partial response. The TUR of patients with complete or partial response (1.91 +/- 0.29 with a 95% confidence interval (95% CI): 1.75-2.07) was significantly higher than that of patients with no response or progressive disease (1.19 +/- 0.28 with a 95% CI: 1.04-1.35).

CONCLUSION

Tc-99m MIBI chest images are a potential tool for understanding Pgp and MRP expressions in SCLC and for predicting patient chemotherapy response.

To predict chemotherapy response using technetium-99m tetrofosmin and compare with p-glycoprotein and multidrug resistance related protein-1 expression in patients with untreated small cell lung cancer

The aim of this study was to investigate the relationships among technetium-99m tetrofosmin (Tc-TF) accumulation in untreated small cell lung cancer (SCLC), the expression of P-glycoprotein (Pgp) and multidrug resistance related protein-1 (MRP1), and the response to chemotherapy in patients with untreated SCLC. Thirty patients with SCLC were studied with chest scintigraphy 15 to 30 min after intravenous injection of Tc-TF before chemotherapeutic induction. Tc-TF chest scans were interpreted both visually and quantitatively. The response to chemotherapy was evaluated upon completion of chemotherapy. Immunohistochemical analyses were performed on multiple non-consecutive sections of biopsy specimens to detect Pgp and MRP1 expression. Fifteen patients with good response to chemotherapy had a significantly higher incidence (100.0%) of positive Tc-TF chest single photon emission computed tomography (SPECT) findings and negative Pgp or MPR expression than 15 patients with poor response (20%) (P<0.05). The tumor/background (T/B) ratios were 1.8+/-0.3 and 1.2+/-0.3 for patients with good response and poor response, respectively (P<0.05). However, other prognostic factors (performance status, tumor size and stage) were not significantly related to Tc-TF chest scan findings and response to chemotherapy. Tc-TF chest scintigraphy correlated well with Pgp or MRP1 expression and accurately predicted the response to chemotherapy in patients with SCLC.

The role of extracellular matrix in small-cell lung cancer

Lung cancer is the most common fatal malignant disease in the western world, accounting for 42,000 deaths each year in the UK alone. Small-cell lung cancer (SCLC), accounts for 25% of all lung cancers. It is a particularly aggressive form of the disease, characterised by widespread metastases and the development of resistance to chemotherapy. Even with combination chemotherapy and radiotherapy treatments, the 5-year survival is only about 5%. We review recent insights into the mechanisms underlying the development of metastases and resistance to chemotherapeutic agents in SCLC, focusing on the role of the extracellular matrix (ECM). We discuss the regulation of the interactions between cells and the ECM and the effects of these interactions on cellular phenotypes, together with some of the new approaches for combating drug resistance and metastases in this disease.

Assessment of IAP (inhibitor of apoptosis) proteins as predictors of response to chemotherapy in advanced non-small-cell lung cancer patients

BACKGROUND

Expression of inhibitor of apoptosis family proteins (IAPs) has been shown in vitro to decrease chemosensitivity through caspase inhibition. However, the role of IAPs as predictors of response to chemotherapy in cancer patients remains to be determined.

PATIENTS AND METHODS

Using immunohistochemistry, we assessed the expression of the IAP proteins c-IAP1, c-IAP2, and XIAP on tumors from 55 patients with advanced non-small-cell lung cancer (NSCLC) treated with chemotherapy, and correlated that with the observed response to chemotherapy, time to progression and overall survival.

RESULTS

Differences were observed in the pattern of staining among the IAP proteins. The expression of c-IAP2 and XIAP was exclusively cytoplasmic. whereas c-IAP1 also displayed nuclear staining. The median expression of tumor cells for c-IAP1, c-IAP2, and XIAP was 70%, 45%, and 25%, respectively, and a correlation was observed between c-IAP1 and c-IAP2 (P = 0.004), and c-IAP1 and XIAP expression (P = 0.013). However, no association was seen between the expression of these proteins and sex, age, tumor size, stage, histology and grade of differentiation. Interestingly, expression of c-IAP1, c-IAP2, and XIAP did not predict response to chemotherapy. In addition, the expression of IAPs had no impact on the time to progression or overall survival of this group of patients.

CONCLUSIONS

Our results indicate that: 1) there are differences in the level of expression and in the subcellular distribution of c-IAP1, c-IAP2, and XIAP in tumors derived from NSCLC patients. 2) The expression of c-IAP1, c-IAP2 and XIAP does not predict the response to chemotherapy in patients with advanced NSCLC. 3) The relation between expression of IAPs and chemosensitivity in cancer patients may be more complex than anticipated by in vitro data.

The structure of the multidrug resistance protein 1 (MRP1/ABCC1). crystallization and single-particle analysis

Multidrug resistance protein 1 (MRP1/ABCC1) is an ATP-binding cassette (ABC) polytopic membrane transporter of considerable clinical importance that confers multidrug resistance on tumor cells by reducing drug accumulation by active efflux. MRP1 is also an efficient transporter of conjugated organic anions. Like other ABC proteins, including the drug resistance conferring 170-kDa P-glycoprotein (ABCB1), the 190-kDa MRP1 has a core structure consisting of two membrane-spanning domains (MSDs), each followed by a nucleotide binding domain (NBD). However, unlike P-glycoprotein and most other ABC superfamily members, MRP1 contains a third MSD with five predicted transmembrane segments with an extracytosolic NH(2) terminus. Moreover, the two nucleotide-binding domains of MRP1 are considerably more divergent than those of P-glycoprotein. In the present study, the first structural details of MRP1 purified from drug-resistant lung cancer cells have been obtained by electron microscopy of negatively stained single particles and two-dimensional crystals formed after reconstitution of purified protein with lipids. The crystals display p2 symmetry with a single dimer of MRP1 in the unit cell. The overall dimensions of the MRP1 monomer are approximately 80 x 100 A. The MRP1 monomer shows some pseudo-2-fold symmetry in projection, and in some orientations of the detergent-solubilized particles, displays a stain filled depression (putative pore) appearing toward the center of the molecule, presumably to enable transport of substrates. These data represent the first structural information of this transporter to approximately 22-A resolution and provide direct structural evidence for a dimeric association of the transporter in a reconstituted lipid bilayer.

Topoisomerase IIalpha and other drug resistance markers in advanced non-small cell lung cancer

Resistance to chemotherapy is common in non-small cell lung cancer. The aim of this study was to investigate the prognostic impact of in vitro established drug resistance markers on the response to chemotherapy in patients with advanced non-small cell lung cancer. Samples of 38 patients were analyzed by immunohistochemical staining, for topoisomerase IIalpha and IIbeta, Ki-67, MRP and LRP. In addition, mutation analysis of the topoisomerase IIalpha gene, the B/DNBS and the Tyr804 region, was performed. Lung tumor biopsies were taken prior for treatment with one of the following regimens; cisplatin/paclitaxel, cisplatin/VM26 or VP16, or carboplatin/VP16/ifosfamide. Seventeen patients obtained a partial response, 12 had stable disease and nine patients had progressive disease. None of the investigated markers was related with overall response rate. In one sample a point mutation in the B/DNBS region of the topo IIalpha gene was detected which substitutes IIe(510) with Val. This tumor had a partial response to four courses of cisplatin/VP16 treatment. The survival analysis showed that the patients with high topo IIalpha expressing tumors had a significantly worse survival compared with the patients with low or intermediate topo IIalpha expressing tumors. In conclusion, no relation was observed between expression of topoisomerase IIalpha, IIbeta, Ki-67, MRP or LRP and response rate. Furthermore, worse survival was seen in patients with high topoisomerase IIalpha expressing tumors. In one tumor sample, a newly described mutation in the B/DNBS region of the topo IIalpha gene was detected, which does not appear to be related to drug resistance.

Evaluation of DNA topoisomerase IIalpha expression provides independent prognostic information in non-Hodgkin's lymphomas

AIMS

In view of the dual role that DNA topoisomerase IIa (TopoIIa) plays as a cell proliferation marker and as a possible indicator of chemosensitivity, we investigated its expression in non-Hodgkin's lymphomas (NHL) in relation to conventional clinicopathological parameters, cell proliferation (as defined by Ki67 immunoreactivity), response to therapy and patient outcome.

METHODS AND RESULTS

Formalin-fixed paraffin-embedded tissues from 153 patients with NHL were immunohistochemically stained for TopoIIalpha. Patients were followed up until death (n = 63) or for an average of 68 months (median 64 months, n = 90). The percentage of TopoIIalpha positive cells (TopoIIalpha LI) increased with grade (P < 0.001), extranodal location (P = 0.05) and Ki67 LI (P = 0.01, r = 0.673). In most cases (58%), Ki67 LI exceeded TopoIIalpha LI (TopoIIalpha/Ki67 < 1), especially within the indolent group (P < 0.001). TopoIIalphaLI, Ki67LI and TopoIIalpha/Ki67 ratio were all adversely related to overall survival in univariate analysis, though their significance was not maintained after adjustment for grade. In multivariate analysis high TopoIIalpha/Ki67 ratio and high TopoIIalpha LI independently predicted shortened overall and post-relapse survival, respectively. Most importantly, low TopoIIalpha/Ki67 ratio was the only independent predictor of diminished disease-free survival. However, there was no relationship between TopoIIalpha expression and response.

CONCLUSIONS

Our results suggest that evaluation of TopoIIalpha expression and TopoIIalpha/Ki67 ratio as cell proliferation markers provides independent prognostic information in relation to post-relapse and overall survival. Furthermore, TopoIIalpha/Ki67 ratio appears to play a key role in the identification of patients prone to early relapse.

Simultaneous quantitation of topoisomerase II alpha and beta isoform mRNAs in lung tumor cells and normal and malignant lung tissue

Certain drugs used in the treatment of lung cancer and other human malignancies are cytotoxic because of their ability to interact with the two isoforms of topoisomerase II (topo II), topo IIalpha and topo IIbeta. As part of an effort to evaluate the contribution of topo II alterations to drug sensitivity and resistance in lung cancer, we have developed a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay to measure levels of topo II alpha and beta mRNAs simultaneously using a single pair of primers with sequences common to both isoforms. The PCR products derived from the topo II alpha and beta mRNAs are both 446 bp but have different electrophoretic mobilities in a nondenaturing polyacrylamide gel, allowing sensitive, rapid quantitation when the products are radiolabeled with [35S]-dATP. Using this RT-PCR method, poly(A+) RNA from 13 non-small cell lung cancer (NSCLC) cell lines was analyzed. The results obtained indicated that the cell lines express a wide range of topo II alpha mRNA levels (12-fold) and topo IIbeta mRNA levels (5.5-fold). Tumor and normal lung tissues from 25 patients with NSCLC were also examined. In the tumor samples, the levels of the topo II alpha and beta mRNAs were similar. However, mean topo IIalpha mRNA levels in the tumors were approximately 7-fold higher than those of the paired normal lung tissues. In contrast, topo IIbeta mRNA levels were similar in both tumor and normal lung. Topo II alpha and beta mRNA levels were both significantly lower in the squamous cell tumors than in the adenocarcinoma samples. Topo IIbeta mRNA levels in the squamous cell tumors were also significantly lower than those in paired normal lung tissue. The RT-PCR method described is reliable and convenient, and for the first time, makes the rapid simultaneous direct comparison of topo IIalpha and topo IIbeta mRNA levels feasible in large numbers of clinical samples.

Expression of drug resistance-related genes in head and neck squamous cell carcinomas and normal mucosa

We examined the expression levels of mRNA for multidrug resistance 1 (MDR1), multidrug resistance-associated protein (MRP), human canalicular multispecific organic anion transporter (cMOAT), lung resistance-related protein (LRP), topoisomerase IIalpha, beta (Topo IIalpha, beta) and topoisomerase I (Topo I) genes in human head and neck squamous cell carcinoma (HNSCC) specimens and mucosa (HNM) specimens, to elucidate their roles in relation to the biological characteristics and drug resistance in vivo. Fifty-eight samples (45 head and neck carcinomas and 13 head and neck mucosa) obtained during surgical resection or biopsy from 38 patients were analyzed using the quantitative reverse transcription-polymerase chain reaction (RT-PCR) method. MDR1, MRP, LRP, Topo IIalpha, Topo IIbeta, and Topo I gene transcripts were detected in all the samples tested, but cMOAT mRNA was not detected in them. Comparisons of the expression levels in HNSCC with those in HNM showed that the Topo IIalpha gene expression level was higher in HNSCC than in HNM (P=0.0298). Moreover, the Topo IIalpha mRNA level was significantly higher in metastatic lymph node samples of HNSCC than in HNM samples (P=0.0205). There were no significant differences in the six genes' expression levels between samples exposed to platinum drugs and those not exposed to platinum drugs. These results suggest that it may be effective in anticancer therapy to use topoisomerase-targetting drugs against HNSCC, especially metastatic neck tumors, and that the expression of these genes in HNSCC is not associated with platinum drug exposure.

ATPase activity of purified and reconstituted multidrug resistance protein MRP1 from drug-selected H69AR cells

The ATP-binding cassette transporter protein, multidrug resistance protein MRP1, was purified from doxorubicin-selected H69AR lung tumor cells which express high levels of this protein. A purification procedure comprised of a differential two-step solubilization of MRP1 from plasma membranes with 3-(3-cholamidopropyl)dimethylammonio-1-propanesulfonate followed by immunoaffinity chromatography using the MRP1-specific monoclonal antibody QCRL-1 was developed. Approximately 300 microgram of MRP1 was obtained from 6 mg of plasma membranes at 80-90% purity, as indicated by silver staining of protein gels. After reconstitution of purified MRP1 into proteoliposomes, kinetic analyses indicated that its K(m) for ATP hydrolysis was 104+/-22 microM with maximal activity of 5-10 nmol min(-1) mg(-1) MRP1. MRP1 ATPase activity was further characterized with various inhibitors and exhibited an inhibition profile that distinguishes it from P-glycoprotein and other ATPases. The ATPase activity of reconstituted MRP1 was stimulated by the conjugated organic anion substrates leukotriene C(4) (LTC(4)) and 17beta-estradiol 17-(beta-D-glucuronide) with 50% maximal stimulation achieved at concentrations of 150 nM and 1.6 microM, respectively. MRP1 ATPase was also stimulated by glutathione disulfide but not by reduced glutathione or unconjugated chemotherapeutic agents. This purification and reconstitution procedure is the first to be described in which the ATPase activity of the reconstituted MRP1 retains kinetic characteristics with respect to ATP-dependence and substrate stimulation that are very similar to those deduced from transport studies using MRP1-enriched plasma membrane vesicles.

Paclitaxel and carboplatin in the treatment of small-cell lung cancer patients resistant to cyclophosphamide, doxorubicin, and etoposide: a non-cross-resistant schedule

PURPOSE

To evaluate the efficacy of paclitaxel and carboplatin (PC) in small-cell lung cancer (SCLC) patients resistant to cyclophosphamide, doxorubicin, and etoposide (CDE).

PATIENTS AND METHODS

We performed a phase II study with PC in SCLC patients who relapsed within 3 months after first-line treatment with CDE. Paclitaxel administration (175 mg/m2 by a 3-hour intravenous infusion) was followed by a 30-minute infusion of carboplatin (area under the curve 7; Chatelut formula) once every 3 weeks for five cycles. Dexamethasone, clemastine, and ranitidine were standard premedication before every cycle.

RESULTS

Included were 35 patients (median age, 59 years; 16 with limited disease and 19 with extensive disease; Eastern Cooperative Oncology Group performance status of < or = 1; median time off treatment 6 weeks) who were previously treated with CDE (n = 33), oral etoposide (n = 2), and reinduction CDE (n = 15); only one patient had received three CDE treatments of five cycles. The CDE regimen was followed by local thoracic radiotherapy in seven patients. Hematologic toxicity of grade 3 or 4, for leukopenia was 27% and 6%, for thrombocytopenia 21% and 13%, and for anemia 17% and 0%, respectively, for a total of 132 cycles. Two patients had neutropenic fever; no toxic death occurred. Nonhematologic toxicity was paresthesia CTC grade 3, diarrhea grade 4, and myalgia grade 3 in one patient each. Reversible paresthesia (CTC grade 1 and 2) in toes and fingers was reported in 69% of patients. Thirty-four patients were assessable for response: complete response in two patients, partial response in 23 patients, stable disease in eight patients, and progressive disease in one patient (response rate, 73.5%; 95% confidence interval, 59% to 88%). One patient was found to have atypical carcinoid at pathologic review and was excluded. Median time to progression was 21 weeks (range, 3 to 40 weeks). Median survival was 31 weeks (range, 6 to 112 weeks). One-year survival was 9%.

CONCLUSION

Second-line PC in CDE-resistant SCLC patients yields a high response rate and seems non-cross-resistant to CDE. Toxicity was mild in these poor-prognosis patients.