Immunohistochemical p53 protein status in nonsmall cell lung cancer is a promising indicator in determining in vitro chemosensitivity to some anticancer drugs

The nuclear expression of poly (ADP-ribose) polymerase-1 (PARP1) in invasive primary breast tumors is associated with chemotherapy sensitivity

It has been reported that expression levels of DNA repair genes are frequently associated with chemotherapy sensitivity and prognosis in breast cancer (BC) subtypes. The poly (ADP-ribose) polymerase-1 (PARP1), one of the major DNA single-strand break (SSBs) repair proteins, has been demonstrated a role in BC development. Because many of the chemotherapeutic agents target the tumor cell DNA, a DNA damage repair protein function is expected to impact therapeutic responses. However, the predictive effect of PARP1 in neoadjuvant chemotherapy (NC) treated BC is still controversial. To investigate whether PARP1 expression in BC is a possible biomarker to predict chemotherapeutic response, we assessed PARP1 expression in BC specimens based on collagen gel droplet embedded culture-drug sensitivity test (CD-DST) (in vitro) results and chemotherapeutic response of NC (in vivo). The surgical specimens from 108 patients with BC were recruited for CD-DST and PARP1 immunohistochemistry. We found that higher nuclear PARP1 (nPARP1) expression correlated with increased in vitro chemosensitivity against docetaxel (p=0.001) and epirubicin (p=0.022) based on CD-DST results. We also found that tumors with high nPARP1 expression were more sensitive to anthracycline/taxane based chemotherapy and associated with pathologic responses to NC using univariate and multivariate analyses (p=0.019 and p=0.037, respectively). Taken together, we conclude that nuclear expression of PARP1 is a useful marker to predict BC therapeutic responses.

Collagen gel droplet-embedded culture-drug sensitivity test and Ki67 expression in estrogen receptor-positive and HER2-negative breast cancer

Anthracyclines and taxanes are standard anticancer drugs used in breast cancer chemotherapy. In general, the efficacy of chemotherapy is lower in patients with estrogen receptor (ER)-positive tumors compared to patients with ER-negative tumors. Although less chemosensitive, ER-positive disease includes a subset of patients who significantly benefit from adjuvant chemotherapy. The collagen gel droplet-embedded culture-drug sensitivity test (CD-DST) is an in vitro chemosensitivity test that has several advantages over conventional tests. The aim of the present study was to examine the correlation between CD-DST and the expression of Ki67, an indicator of tumor proliferation, to evaluate the efficacy of anthracyclines and taxanes in patients with ER-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. CD-DST was performed in 68 patients with ER-positive and HER2-negative breast cancer between August 2001 and November 2006. The specimens obtained during surgery were used for the CD-DST and immunohistological examination of Ki67 expression. Chemosensitivity to the anticancer drugs adriamycin (ADM), epirubicin (EPI), docetaxel (DOC) and paclitaxel (PTX) was estimated using CD-DST. Results obtained from the CD-DST showed the chemosensitivity to each anticancer drug to be ADM, 23.7%; EPI, 75.0%; DOC, 69.2% and PTX, 43.6%. Ki67 expression was significantly higher in the group that was sensitive to DOC compared to the group that was resistant to DOC (P=0.048) and PTX (P=0.036). In addition, a significant correlation was observed between a Ki67 labeling index (LI) of >30% and chemosensitivity to PTX. In conclusion, results obtained from CD-DST and Ki67 expression levels are able to identify a subset of patients with ER-positive and HER2-negative breast cancer who exhibit sensitivity to chemotherapy, particularly to taxane therapy.

TP53 mutations in nonsmall cell lung cancer

The tumor suppressor gene TP53 is frequently mutated in human cancers. Abnormality of the TP53 gene is one of the most significant events in lung cancers and plays an important role in the tumorigenesis of lung epithelial cells. Human lung cancers are classified into two major types, small cell lung cancer (SCLC) and nonsmall cell lung cancer (NSCLC). The latter accounts for approximately 80% of all primary lung cancers, and the incidence of NSCLC is increasing yearly. Most clinical studies suggest that NSCLC with TP53 alterations carries a worse prognosis and may be relatively more resistant to chemotherapy and radiation. A deep understanding of the role of TP53 in lung carcinogenesis may lead to a more reasonably targeted clinical approach, which should be exploited to enhance the survival rates of patients with lung cancer. This paper will focus on the role of TP53 in the molecular pathogenesis, epidemiology, and therapeutic strategies of TP53 mutation in NSCLC.

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.

Collagen gel droplet-embedded culture drug-sensitivity test and potential for personalizing cancer treatment

Sensitivity testing for general anticancer agents involves culturing cancer cells, exposure to an anticancer agent, and assessing the degree of growth inhibition. One such method is the collagen gel droplet-embedded culture drug-sensitivity test (CD-DST). Clinical results confirm a close correlation of a better than 75% accuracy between CD-DST results and responses to anticancer agents administered in the clinical setting. Although there have been few randomized, controlled studies of the CD-DST method, the general observation is that cancer patients survive longer if their disease responds to an anticancer agent than if it is ineffective. Therefore, it can be extrapolated that the high diagnostic accuracy of CD-DST is indirect evidence that this method can be used to select the group for whom chemotherapy will be effective, with a resultant prolongation of their survival time, and the group for whom chemotherapy will be ineffective, with no increased survival time.

Evaluation of 5-fluorouracil applicability by the collagen gel droplet embedded drug sensitivity test with area under the curve analysis

We have evaluated the 5-fluorouracil sensitivity of cancer cells from colorectal cancer patients using the collagen gel droplet embedded drug sensitivity test under multiple drug concentrations and contact durations. After converting drug concentration and contact time to the area under the curve (AUC) and plotting against the growth inhibition rate, the correlation between AUC and the growth inhibition rates was approximated to the logarithmic regression curve. In this study, to further validate the reliability of the regression curve, the growth inhibition rate was calculated from the regression curve and the actual growth inhibition rate was compared at AUC of 48 mug h/ml. No significant difference was observed in the growth inhibition rates between the two groups by paired t-test (P=0.590). A strong positive correlation was found between the two groups by regression analysis (y=0.7555x+10.514, R=0.8236). This result strongly suggests that in-vitro antitumor effect of 5-fluorouracil depends on the AUC in colorectal cancer and the AUC-inhibition rate curve is reliable. We can obtain the inhibition rate from AUC and vice versa using the AUC-inhibition rate curve. We can also calculate the individualized AUCIR50, AUC value that gives 50% growth inhibition, using the AUC-inhibition rate curve. This could be useful to establish individualized chemotherapy using the collagen gel droplet embedded drug sensitivity test.

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.

The TP53 gene, tobacco exposure, and lung cancer

Of the various genetic alterations in lung cancer, the abnormalities of the TP53 gene (p53) are among the most frequent and important events. Because of its importance, many aspects of TP53 have been studied, including preneoplastic lesions and TP53as a marker for early detection and prognosis and as a therapeutic option. We summarize recent knowledge of TP53 in lung cancer with a special emphasis on the relationship between smoking exposure (e.g, cigarette, etc.) and specific mutational pattern of TP53by analyzing the latest version of the International Agency for Research on Cancer (IARC) database on TP53 mutations in human cancer. Our analysis confirmed several other studies showing significant differences in the frequencies of G:C to T:A transversions between ever-smokers and never-smokers. Furthermore, when comparing the mutational spectrum by gender, important differences were noted between male and female never-smokers. We concluded that the previously noted G:C to T:A transversions were mainly due to female smokers having a high frequency of these changes compared to female never-smokers. There was no relationship between adenocarcinomas and squamous cell carcinomas independent of gender. We also examined the seven codons which have been previously identified as hot spots, that is, the sites of frequent G:C to T:A transversions in smoking-related lung cancers. However, there was no specific codon which was strongly related to smoke exposure despite a moderate relationship. We considered the term "warmspot" may be more appropriate. While mutations of TP53 are frequent in lung cancers, further investigation is necessary to understand their role for lung carcinogenesis, especially as they relate to gender differences, and to translate our laboratory knowledge to clinical applications.

Prediction of chemotherapeutic response by collagen gel droplet embedded culture-drug sensitivity test in human breast cancers

Collagen gel droplet embedded culture-drug sensitivity test (CD-DST) is the newly developed in vitro chemosensitivity test that has several advantages over the conventional ones. The aim of the present study is to examine the clinical usefulness of this test in the prediction of response to chemotherapy in breast cancer patients. Seventy patients with primary (n = 45) or locally recurrent (n = 25) breast cancers were recruited, and each patient underwent tumor biopsy before chemotherapy. The biopsy specimens were used for CD-DST and immunohistological examination of 6 biological markers (P-gp, erbB2, p53, BCL2, MIB1 and ER-alpha). As chemotherapy, cyclophosphamide 600 mg/m(2) plus epirubicin 60 mg/m(2) q3w (CE, n = 28) or docetaxel 60 mg/m(2) q3w (DOC, n = 42) was given. Interpretable results using the CD-DST assay were obtained from 84.3% (59/70) of tumor specimens studied. Of the 18 tumors diagnosed as CE sensitive by CD-DST, 15 (83.3%) exhibited a response to CE therapy and none of the 5 tumors diagnosed as CE resistant by CD-DST exhibited a response to CE therapy. Of the 14 tumors diagnosed as DOC sensitive by CD-DST, 13 (92.9%) exhibited a response to DOC therapy and only one of the 22 tumors diagnosed as DOC resistant by CD-DST exhibited a response to DOC therapy. P-gp expression was found to exhibit a significant (p < 0.05) association with the resistance to CE therapy but not to DOC therapy. Diagnostic accuracy (72.7%) achieved by P-gp was lower than that (87.0%) achieved by CD-DST in CE therapy. Expressions of other biological markers (erbB2, p53, BCL2, MIB1 and ER-alpha) were not significantly associated with response to CE or DOC therapy. These results demonstrate that CD-DST can predict the response to CE and DOC therapy with a high accuracy in breast cancer patients and seems to be superior to the conventional predictors.

Thymidylate synthase and dihydropyrimidine dehydrogenase activities in non-small cell lung cancer tissues: relationship with in vitro sensitivity to 5-fluorouracil

We examined enzymatic activities of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) in non-small cell lung cancer (NSCLC) tissues to determine the relationship to tumor sensitivity to 5-fluorouracil (5-FU). TS and DPD activities were measured in 60 surgically resected primary NSCLC tissues using a TS-binding assay and a radioenzyme assay, respectively. In vitro tumor sensitivity to 5-FU was assayed using a collagen gel droplet embedded culture drug test (CD-DST). DPD activities slightly correlated with in vitro sensitivity to 5-FU (r=0.402,P=0.013), such that tumors with higher DPD activity were more resistant to 5-FU. In contrast, no correlation was observed in TS activities. Thus, it was suggested that only DPD activity in NSCLC tissues is a potential indicator in predicting tumor sensitivity to 5-FU. Based on these results, further study is needed to evaluate the clinical significance of these enzymes in 5-FU-based chemotherapy for patients with NSCLC.

Correlation of p53 oncoprotein expression with chemotherapy response in small cell lung carcinomas

p53 oncoprotein expression was investigated in small cell lung carcinomas (SCLC) using immunohistochemical staining with antibodies against p53. A total of 50 pre-treatment biopsies were examined. We analyzed the relationship between p53 expression and these patients' relevant clinical characteristics, response to chemotherapy, time to progression, and overall survival. We found p53 overexpression in 46% of the samples but no association with clinical data or overall survival. Our results show a strong correlation of p53 staining with chemotherapy response. Multivariate analysis selected p53 as an independent predictive factor of chemotherapy response.

Examination of in vitro chemosensitivity test using collagen gel droplet culture method with colorimetric endpoint quantification

To develop a simpler method of performing the collagen gel droplet-embedded culture drug sensitivity test (CD-DST), we examined the introduction of colorimetric quantitative determination of images for evaluation of anticancer effect against cancer cells alone in the presence of fibroblasts, based on differences in proliferative morphology and stainability with neutral red of cells within collagen gel drops determined using a video-microscope and NIH Image software. In examinations using a human cancer cell line and a fibroblast cell line, a high degree of linearity between number of cancer cells and image-optical density was found within the range of 10(2) - 10( 6) cells / droplet (r (2) = 0.933). Using NIH Image, fibroblast cells could be eliminated at a cut-off value of 128, and an immunocytochemical method demonstrated that the cells eliminated from the image were indeed fibroblasts, and those remaining were cancer cells. CD-DST was carried out with mixtures of cancer cells with fibroblasts at various ratios, and the feasibility of evaluating anticancer activity in cancer cells alone with no effect of fibroblasts at any mixing ratio was confirmed. In addition, for CD-DST of primary cell cultures of human lung cancers collected at the time of surgery, a high correlation between results obtained with the volume supplementation method, a current cell quantification method, and those with the imaging colorimetric quantification method was obtained (r = 0.933). These results indicate that introduction of imaging colorimetric quantification utilizing NIH Image makes CD-DST a quick and simple method that should be highly useful for clinical chemosensitivity testing using primary cell cultures of human cancers.

p53-regulated GML gene expression in non-small cell lung cancer. a promising relationship to cisplatin chemosensitivity

The GML gene (glycosylphosphatidylinositol-anchored molecule-like protein gene) is a novel gene specifically induced by wild-type p53, which may participate in cell cycle control or the cell apoptotic pathway. Recent experiments suggest that the expression of this novel gene in cancer cells is closely associated with sensitivity to certain anticancer drugs. To elucidate the role of the gene expression in cisplatin (CDDP) chemosensitivity of non-small cell lung cancer (NSCLC), 30 surgically resected materials were examined by reverse transcriptase-polymerase chain reaction (RT-PCR). GML gene expression was detected in 9 (30%) samples. Its incidence was significantly higher in immunohistochemically p53-negative (P=0.040) or wild-type p53 tissues (P=0.041). On in vitro chemosensitivity testing using 29 primary tissues, six samples with GML gene expression showed good sensitivity to CDDP. In particular, in tissues with immunohistochemically p53-negative accumulation, those with GML gene expression showed significantly better in vitro sensitivity to CDDP (P=0.012). Clinically a good response to CDDP-based chemo(thermo)therapy for NSCLC patients with tumour residue or recurrence, was observed only in those with p53-negative accumulation and GML gene expression, in agreement with in vitro results. Thus, although the number of tested samples was small, GML gene expression is commonly detected in immunohistochemically p53-negative NSCLCs in close association with good sensitivity to CDDP. GML gene expression analysis may serve as a predictor of CDDP-based chemotherapy for patients with NSCLC.

p53 and chemosensitivity

BACKGROUND

Although hematologic malignancies and some solid tumors such as germ cell tumors and pediatric malignancies can be cured by cytotoxic treatment, the most prevalent solid tumors are relatively resistant to these interventions. Apoptosis is involved in the cell kill of anticancer drugs and p53 is believed to be of principal importance in this process. However p53 also plays a role in cell cycle arrest and DNA repair, cellular processes that can decrease the sensitivity to chemotherapy. Therefore, p53 may play a dual role after exposure to cytotoxic treatment, activating either mechanisms that lead to apoptosis or launching processes directing to DNA repair and survival of the cell.

DESIGN

In this article, we review in details the p53 functions involved in the mediation of chemosensitivity. The preclinical and clinical data published in the recent years about the relation between p53 and chemosensitivity are discussed and the potential pitfalls associated to most of these studies, and that may account for the contradictory results produced so far are also mentioned.