Interrelationships between cellular nucleotide excision repair, cisplatin cytotoxicity, HER-2/neu gene expression, and epidermal growth factor receptor level in non-small cell lung cancer cells

Elevated HMGB1 promotes the malignant progression and contributes to cisplatin resistance of non-small cell lung cancer

BACKGROUND

HMGB1 (high mobility group box B-1) exhibits crucial role in tumor genesis and development, including lung cancer. Whereas, more HMGB1-related details in non-small cell lung cancer (NSCLC) are still largely unclear.

METHODS

The HMGB1 and inflammatory factors in malignant (MPE) and non-malignant pleural effusion (BPE) were determined by ELISA. Additionally, qRT-PCR, western blot, or immunohistochemistry were used to determine HMGB1, drug-resistant and apoptotic proteins' expressions in NSCLC A549, A549-DDP cell lines, and xenograft model. Cell viability, migration/ invasion, and apoptosis were analyzed using MTT, Transwell, and flow cytometry assays, respectively.

RESULTS

Inflammatory factors and HMGB1 expressions in MPE were significantly higher than BPE of NSCLC. Compared with preoperative and adjacent tissues, significantly higher HMGB1, drug-resistant protein, and anti-apoptotic protein expressions were observed in recurrent tissues. Overexpressed HMGB1 induced NSCLC cells to exhibit stronger aggressive, proliferative, and drug-resistant features. The related abilities were reversed when HMGB1 was interfered. Overexpressed HMGB1 showed a similar co-localization with drug resistant protein P-gp in cytoplasm in xenograft model, while low HMGB1 expression localized in cell nucleus.

CONCLUSIONS

HMGB1 overexpression significantly promoted the malignant progression and cisplatin resistance of NSCLC in vitro and in vivo.

[Association between the HER2 Gene Status and the Efficacy of First-line Pemetrexed Combined with Platinum Chemotherapy in Patients with Advanced Lung Adenocarcinoma]

BACKGROUND

Human epidermal growth factor receptor 2 (HER2) is one of the driver genes of non-small cell lung cancer (NSCLC). Several studies have shown that the efficacy of pemetrexed in HER2-mutant NSCLC is controversial. The aim of this study is to investigate the efficacy of pemetrexed combined with platinum chemotherapy in patients with HER2-mutant and HER2 wild-type lung adenocarcinoma.

METHODS

The clinical data of 106 cases of EGFR, ALK, ROS-1, KRAS, BRAF, RET and MET-negative patients with advanced lung adenocarcinoma patients who diagnosed by histopathology in the First Affiliated Hospital of Zhengzhou University were retrospectively reviewed. The relationships between HER2 gene status, clinical characteristics and response and progression-free survival (PFS) were analyzed.

RESULTS

All of the 106 patients' HER2 status were determined. HER2 mutations occurred in 32 cases (30.2%), no mutations in 74 cases (69.8%). HER2 mutations were common in young, non-smoking and female patients. All patients received first-line pemetrexed and platinum-based chemotherapy. The objective response rate (ORR) and disease control rate (DCR) of patients with HER2-mutant lung adenocarcinoma were significantly higher than those without HER2 mutations (40.6% vs 14.9%, χ²=8.464, P=0.004; 93.8% vs 68.9%, χ²=6.327, P=0.012), and the difference was statistically significant. According to univariate analysis, the PFS was significantly associated with the brain metastases, maintenance chemotherapy and HER2 gene status (P<0.05), but not with age, gender, smoking history, oligometastases, liver metastases and type of platinum (P>0.05). Cox multivariate analysis indicated that HER2 mutation was an independent positive prognostic factor of PFS (P=0.038).

CONCLUSIONS

HER2-mutant lung adenocarcinoma patients with first-line pemetrexed combined with platinum chemotherapy have greater clinical benefit than HER2 wild-type patients.

Mapping genetic alterations causing chemoresistance in cancer: identifying the roads by tracking the drivers

Although new agents are implemented to cancer therapy, we lack fundamental understandings of the mechanisms of chemoresistance, the main obstacle to cure in cancer. Here we review clinical evidence linking molecular defects to drug resistance across different tumour forms and discuss contemporary experimental evidence exploring these mechanisms. Although evidence, in general, is sparse and fragmentary, merging knowledge links drug resistance, and also sensitivity, to defects in functional pathways having a key role in cell growth arrest or death and DNA repair. As these pathways may act in concert, there is a need to explore multiple mechanisms in parallel. Taking advantage of massive parallel sequencing and other novel high-throughput technologies and base research on biological hypotheses, we now have the possibility to characterize functional defects related to these key pathways and to design a new generation of studies identifying the mechanisms controlling resistance to different treatment regimens in different tumour forms.

Biomarkers of DNA repair and related pathways: significance in non-small cell lung cancer

PURPOSE OF REVIEW

To review selected biomarkers of DNA repair and related pathways as they relate to the management of patients with non-small cell lung cancer (NSCLC), emphasizing the role of individualized, chemotherapy for advanced disease, and discussing potential applications in early disease.

RECENT FINDINGS

The activity of molecular-targeted agents in NSCLC patients whose tumor possesses relevant biomarkers [such as epidermal growth factor receptor (EGFR) activating mutations and ALK translocations] has made personalized therapy possible. In addition, preclinical and clinical studies have shown that histopathological and biomolecular factors can correlate with clinical outcome in patients with NSCLC treated with chemotherapy. As a result, tumor histology is now routinely considered in selecting chemotherapy for NSCLC patients, such as pemetrexed for nonsquamous histology. Molecular tumor and host factors, including genes involved in DNA-repair and synthesis, are potentially even more relevant as predictive biomarkers of tumor response to chemotherapy. However, individual molecular markers and gene signatures need further validation and standardization, before routine use in the clinic can be recommended.

SUMMARY

In the era of molecular-targeted agents, individualized therapy based on molecular biomarkers has become a reality in the treatment of patients with advanced NSCLC. Further studies are needed to optimize current treatment algorithms with regard to biomarkers for chemotherapy benefit, to refine molecular markers, and to translate these findings to early stage NSCLC.

EGFR(s) in aging and carcinogenesis of the gastrointestinal tract

Cells of the gastrointestinal (GI) mucosa are subject to a constant process of renewal which, in normal adults, reflects a balance between the rates of cell production and cell loss. Detailed knowledge of these events is, therefore, essential for a better understanding of the normal aging processes as well as many GI diseases, particularly malignancy, that represent disorders of tissue growth. In general, many GI dysfunctions, including malignancy, increase with advancing age, and aging itself is associated with alterations in structural and functional integrity of the GI tract. Although the regulatory mechanisms for age-related increase in the incidence of GI-cancers are yet to be fully delineated, recent evidence suggests a role for epidermal growth family receptors and its family members {referred to as EGFR(s)} in the development and progression of carcinogenesis during aging. The present communication discusses the involvement of EGFR(s) in regulating events of GI cancers during advancing age and summarizes the current available therapeutics targeting these receptors. The current review also describes the effectiveness of ErbB inhibitors as well as combination therapies. Additionally, the involvement of GI stem cells in the development of the age-related rise in GI cancers is emphasized.

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.

The 3p21.3 tumor suppressor NPRL2 plays an important role in cisplatin-induced resistance in human non-small-cell lung cancer cells

NPRL2 is one of the novel candidate tumor suppressor genes identified in the human chromosome 3p21.3 region. The NPRL2 has shown potent tumor suppression activity in vitro and in vivo and has been suggested to be involved in DNA mismatch repair, cell cycle checkpoint signaling, and regulation of the apoptotic pathway. In this study, we analyzed the endogenous expression of the NPRL2 protein and the cellular response to cisplatin in 40 non-small-cell lung cancer cell lines and found that expression of NPRL2 was significantly and reciprocally correlated to cisplatin sensitivity, with a Spearman correlation coefficient of -0.677 (P < 0.00001). Exogenously introduced expression of NPRL2 by N-[1-(2,3-dioleoyloxyl)propyl]-NNN-trimethylammoniummethyl sulfate:cholesterol nanoparticle-mediated gene transfer significantly resensitized the response to cisplatin, yielding a 40% greater inhibition of tumor cell viability and resulting in a 2- to 3-fold increase in induction of apoptosis by activation of multiple caspases in NPRL2-transfected cells compared with untransfected cells at an equal dose of cisplatin. Furthermore, a systemic treatment with a combination of NPRL2 nanoparticles and cisplatin in a human H322 lung cancer orthotopic mouse model significantly enhanced the therapeutic efficacy of cisplatin and overcame cisplatin-induced resistance (P < 0.005). These findings implicate the potential of NPRL2 as a biomarker for predicting cisplatin response in lung cancer patients and as a molecular therapeutic agent for enhancing response and resensitizing nonresponders to cisplatin treatment.

Effect of heat shock protein 47 on collagen accumulation in keloid fibroblast cells

BACKGROUND

Keloid is characterized by excessive collagen accumulation, but the mechanism of keloid formation remains unknown, and none of the treatment modalities are consistently effective. Heat shock protein (HSP) 47, known as a collagen-specific molecular chaperone, plays a critical role in collagen biosynthesis. Our previous research has demonstrated that HSP47 is highly expressed in keloid compared with normal skin tissues, which indicates that there might be a close relationship between overexpression of HSP47 and excessive collagen accumulation in keloid formation.

OBJECTIVES

To further investigate whether overexpression of HSP47 might promote excessive collagen deposition in keloid formation, we examined the alteration of intracellular and extracellular collagen expression, following inhibition of HSP47 expression in keloid fibroblast cells by the RNA interference technique.

METHODS

Three constructed psiRNA-hH1neo plasmids, carrying three pairs of related HSP47-shRNA (small hairpin RNA), respectively, were transfected into keloid fibroblast cells and compared with three control groups. After transfection, the mRNA and protein expression of HSP47 and collagen type I were detected by quantitative real-time polymerase chain reaction and Western blot; the content of extracellular secreting collagen was assessed by hydroxyproline assay; and the MTT [3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide] method was adopted to examine the proliferation of keloid fibroblast cells.

RESULTS

Both the mRNA and protein levels of HSP47 in keloid fibroblast cells decreased dramatically 48 h after post-transfection of three related HSP47-shRNA plasmids, compared with control groups. Following the downregulation of HSP47, we found that the expression of intracellular and extracellular collagen was correspondingly reduced. On the other hand, the MTT assay showed that transfection of HSP47-shRNA plasmids did not influence the growth of keloid fibroblast cells.

CONCLUSIONS

Combined with our previous histological results, we propose that overexpression of HSP47 in keloid fibroblast cells could induce excessive collagen accumulation by enhancing synthesis and secretion of collagen, which not only presents a possible mechanism of keloid formation, but also offers a therapeutic potential of RNA interference to HSP47 for the treatment of keloid and other fibroproliferative disorders.

Therapeutic resistance in lung cancer

Despite considerable progress over the last 25 years in the systemic therapy of lung cancer, intrinsic and acquired resistance to chemotherapeutic agents and radiation remains a vexing problem. The number of mechanisms of therapeutic resistance in lung cancer has expanded considerably over the past three decades, and the crucial role of stress resistance pathways is increasingly recognised as a cause of intrinsic and acquired chemo- and radiotherapy resistance. This paper reviews recent evidence for stress defence proteins, particularly RALBP1/RLIP76, in mediating intrinsic and acquired chemotherapy and radiation resistance in human lung cancer.

Silencing the epidermal growth factor receptor gene with RNAi may be developed as a potential therapy for non small cell lung cancer

Lung cancer has emerged as a leading cause of cancer death in the world. Non-small cell lung cancer (NSCLC) accounts for 75-80% of all lung cancers. Current therapies are ineffective, thus new approaches are needed to improve the therapeutic ratio. Double stranded RNA (dsRNA)-mediated RNA interference (RNAi) has shown promise in gene silencing, the potential of which in developing new methods for the therapy of NSCLC needs to be tested. We report here RNAi induced effective silencing of the epidermal growth factor receptor (EGFR) gene, which is over expressed in NSCLC. NSCLC cell lines A549 and SPC-A1 were transfected with sequence- specific dsRNA as well as various controls. Immune fluorescent labeling and flow cytometry were used to monitor the reduction in the production of EGFR protein. Quantitative reverse-transcriptase PCR was used to detect the level of EGFR mRNA. Cell count, colony assay, scratch assay, MTT assay in vitro and tumor growth assay in athymic nude mice in vivo were used to assess the functional effects of EGFR silencing on tumor cell growth and proliferation. Our data showed transfection of NSCLC cells with dsRNA resulted in sequence specific silencing of EGFR with 71.31% and 71.78 % decreases in EGFR protein production and 37.04% and 54.92% in mRNA transcription in A549 and SPC-A1 cells respectively. The decrease in EGFR protein production caused significant growth inhibition, i.e.: reducing the total cell numbers by 85.0% and 78.3%, and colony forming numbers by 63.3% and 66.8%. These effects greatly retarded the migration of NSCLC cells by more than 80% both at 24 h and at 48 h, and enhanced chemo-sensitivity to cisplatin by four-fold in A549 cells and seven-fold in SPC-A1. Furthermore, dsRNA specific for EGFR inhibited tumor growth in vivo both in size by 75.06% and in weight by 73.08%. Our data demonstrate a new therapeutic effect of sequence specific suppression of EGFR gene expression by RNAi, enabling inhibition of tumor proliferation and growth. However, in vivo use of dsRNA for gene transfer to tumor cells would be limited because dsRNA would be quickly degraded once delivered in vivo. We thus tested a new bovine lentiviral vector and showed lentivector-mediated RNAi effects were efficient and specific. Combining RNAi with this gene delivery system may enable us to develop RNAi for silencing EGFR into an effective therapy for NSCLC.

The role of p53 in treatment responses of lung cancer

Resistance to radio- and chemotherapy is a major problem in treatment responses of lung cancer. In this disease, biological markers, that can be predictive of response to treatment for guiding clinical practice, still need to be validated. Radiotherapy and most chemotherapeutic agents directly target DNA and in response to such therapies, p53 functions as a coordinator of the DNA repair process, cell cycle arrest, and apoptosis. In fact, it participates in the main DNA repair systems operative in cells, including NHEJ, HRR, NER, BER, and MMR. Given the high p53 mutation frequency in lung cancer which likely impairs some of the p53-mediated functions, a role of p53 as a predictive marker for treatment responses has been suggested. In this review, we summarize the conflicting results coming from preclinical and clinical studies on the role of p53 as a predictive marker of responses to chemotherapy or radiotherapy in lung cancer.

HER2/neu expression and amplification in non-small cell lung cancer prior to and after neoadjuvant therapy

BACKGROUND

Expression and amplification of the HER2/neu protooncogene was analyzed in locally advanced NSCLC in a multimodality therapy approach in order to obtain information on the predictive value of HER2/neu for success or failure of neoadjuvant therapy.

METHODS

In the scope of a prospective randomized phase III-trial, tumor tissue of pre-therapeutically obtained mediastinal lymph node biopsies (n=105) and corresponding post-surgical resection specimens (n=44) was analyzed by means of immunohistochemistry (DAKO-Hercep-Test) and fluorescence in situ hybridization (FISH). In 58 of 105 patients with metastatic mediastinal lymph node disease the extent of therapy-induced tumor regression could be established.

RESULTS

Concerning HER2/neu expression, 16 lymph node biopsies (15.2%) showed 1+, 2+, or 3+ results. Five of these cases revealed amplification in FISH analysis (4.8%). In 44 corresponding resection specimens, Hercep-Test showed 1+, 2+, or 3+ results in 13 tumors (29.5%). Two of these patients revealed HER2/neu amplification in FISH analysis (4.5%). In patients with HER2/neu expressing tumors a trend towards a less extensive therapy-induced tumor regression could be demonstrated. When comparing pre-therapy and post-surgical results, there was a weak trend towards a selection of HER2/neu expressing tumor tissue in the course of neoadjuvant therapy.

CONCLUSIONS

Only a limited subcollective of locally advanced NSCLC meets the biological requirements for anti-HER2/neu therapy. HER2/neu positive tumors appeared to be relatively resistant to chemotherapy and radiation treatment, none of these cases having a pathological complete or at least subtotal response in the corresponding resection specimens. This observation requires confirmation in large randomized controlled studies.

Growth inhibitory effects of trastuzumab and chemotherapeutic drugs in gastric cancer cell lines

The various treatments for advanced gastric cancer have limitations and induce only marginal survival benefit. HER-2/neu protein is overexpressed in several types of human cancers and its amplification is associated with poor prognosis. Recombinant humanized anti-HER-2/neu antibody (trastuzumab) not only inhibits the proliferation of HER-2/neu overexpressing tumor cells but also augments the cytotoxicity of concomitant chemotherapeutic agents in metastatic breast cancer. In this study, we evaluated the growth inhibitory effects of trastuzumab in gastric cancer cells. HER-2/neu protein was evaluated by immunohistochemical analysis in seven gastric cancer cell lines. MTT assay was performed to evaluate the growth inhibitory effects of trastuzumab and three chemotherapeutic agents, doxorubicin, cisplatin and paclitaxel, both alone and in combinations. The changes of cell cycle after trastuzumab treatment were analyzed by flow cytometry. Four of the cell lines, YCC-2 with strong positivity of HER-2/neu expression, NCI-N87 with moderate positivity, YCC-3 with weak positivity, and SK-BR-3 as a positive control, were selected. After in vitro MTT assay for 1-day and 5 consecutive days' treatment of trastuzumab at various concentrations, growth inhibition was not observed in any cancer cell lines. However, there was variable dose-dependent sensitivity to doxorubicin, cisplatin and paclitaxel. YCC-2 and SK-BR-3 cancer cells were more sensitive to three chemotherapeutic drugs, constantly (P<0.05). The combination of 5 consecutive days' treatment of trastuzumab with 1-day doxorubicin treatment showed significant growth inhibition only in YCC-2 and NCI-N87 gastric cancer cells. After 1-day trastuzumab treatment, the S-phase fraction was decreased by 52 and 70% in YCC-2 and SK-BR-3, respectively. In conclusion, the expressions of HER-2/neu protein in gastric cancer cells are variable, and concomitant treatments of trastuzumab with doxorubicin increase cytotoxicity. This suggests that trastuzumab-based biologic therapy with chemotherapeutic agents can be applied in gastric cancer treatment.

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.

Oncogenic tyrosine kinases and the DNA-damage response

Oncogenic tyrosine kinases (OTKs) are involved in the induction of many types of tumour, including haematological malignancies and cancers of the breast, prostate, colon and lung. Neoplastic cells that express OTKs are usually resistant to apoptosis that is induced by DNA-damaging agents, such as cytostatic drugs and irradiation, and they display genomic instability. So, what are the mechanisms involved, and what is the potential for overcoming OTK-mediated resistance in the clinic?

In vitro establishment of cis-diammine-dichloroplatinum(II) resistant lung cancer cell line and modulation of apoptotic gene expression as a mechanism of resistant phenotype

After exposure of H460 cells to an increasing concentrations of cis-diammine-dichloroplatinum(II) (cisplatin, CDDP) for 6 months, cisplatin resistant cells were isolated (H460/CIS). The biologic behaviors of H460 and H460/CIS cells were tested using animal experiments. Only the resistant cells developed lung metastases despite cisplatin treatment. The characteristics of H460/CIS cells are as follows, MTT analyses revealed that H460/CIS cells were markedly resistant to cisplatin compared with their parental cells. Also, H460/CIS cells exhibited cross-resistance to DNA damaging agents such as doxorubicin (DXR) and etoposide. Cisplatin treatment dramatically increased p53 expression in parental cells but not in H460/CIS cells which expressed basal levels of p53. Without cisplatin treatment, Bcl-2 and Bax were expressed in H460/CIS cells, but not in parental cell. Our data suggested that p53, Bax and Bcl-2 were up-regulated in H460/CIS cells. These changes could explain some of the mechanisms of cisplatin resistance. Thus, H460/CIS could be useful to investigate the mechanisms of drug resistance to cisplatin including apoptotic gene expressions conferring drug resistance, thereby making progress in the treatment of cisplatin-resistant tumor cells.