The role of new targeted therapies in small-cell lung cancer

Genomic deregulation of the E2F/Rb pathway leads to activation of the oncogene EZH2 in small cell lung cancer

Small cell lung cancer (SCLC) is a highly aggressive lung neoplasm with extremely poor clinical outcomes and no approved targeted treatments. To elucidate the mechanisms responsible for driving the SCLC phenotype in hopes of revealing novel therapeutic targets, we studied copy number and methylation profiles of SCLC. We found disruption of the E2F/Rb pathway was a prominent feature deregulated in 96% of the SCLC samples investigated and was strongly associated with increased expression of EZH2, an oncogene and core member of the polycomb repressive complex 2 (PRC2). Through its catalytic role in the PRC2 complex, EZH2 normally functions to epigenetically silence genes during development, however, it aberrantly silences genes in human cancers. We provide evidence to support that EZH2 is functionally active in SCLC tumours, exerts pro-tumourigenic functions in vitro, and is associated with aberrant methylation profiles of PRC2 target genes indicative of a “stem-cell like” hypermethylator profile in SCLC tumours. Furthermore, lentiviral-mediated knockdown of EZH2 demonstrated a significant reduction in the growth of SCLC cell lines, suggesting EZH2 has a key role in driving SCLC biology. In conclusion, our data confirm the role of EZH2 as a critical oncogene in SCLC, and lend support to the prioritization of EZH2 as a potential therapeutic target in clinical disease.

The effects of HIF-1alpha on gene expression profiles of NCI-H446 human small cell lung cancer cells

BACKGROUND

Gene targeted therapy refers to any therapy focused on one of the many biological features of the tumor. Such features are mediated by specific genes that are involved in tumor metastasis, recurrence, poor response to chemotherapy and others. Hypoxia is an important pathognomonic feature of many malignant tumors including SCLC (small cell lung cancer). HIF-1alpha, which is induced by hypoxia, is the most important regulatory factor of many specific genes that can influence the biological features of tumors.

METHODS

In this study, we tried to elucidate the changes in gene expression profiles of SCLC NCI-H446 cells mediated by HIF-1alpha. According to different treatments of cells, three experimental pairwise comparisons were designed: hypoxia group vs. control group, Ad5-HIF-1alpha group vs. Ad5 group, and Ad5-siHIF-1 alpha group Vs Ad5 group.

RESULTS

Results from the analysis of gene expression profiles indicated that there were 65 genes upregulated and 28 genes downregulated more than two-fold in all three experimental pairwise comparisons. These genes were involved in transport, signal-transduction, cell adhesion/motility, growth factor/cytokines, transcription, inflammatory response, metabolic process, in addition to others. SOCS1, IGFBP5, IL-6 and STAT3 were also upregulated at protein level. SOCS1 could significantly induce apoptosis and suppress growth of NCI-H446 cells but HIF-1alpha could induce growth and suppress apoptosis.

CONCLUSIONS

Through this research, we are trying to find novel functional genes that are mediated by HIF-1alpha and provide the theoretical basis for new therapeutic targets. HIF-1 alpha maybe upregulate the expression of SOCS1 through mediation of STAT3 and IL-6. In addition, SOCS1 could significantly induce apoptosis and suppress growth of NCI-H446 cells. This was contrary to HIF-1alpha and it indicated that there might be an antagonism effect between HIF-1alpha and SOCS1 on regulating growth and apoptosis of NCI-H446 cells.

Hypoxia inducible factor-1 alpha and vascular endothelial growth factor in biopsies of small cell lung carcinoma

Neoangiogenesis has been documented in small cell lung carcinoma (SCLC). In addition, antiangiogenic therapies are being tested in clinical trials that involve SCLC. However, study of the underlying mechanisms has been performed almost exclusively in cell lines. In the current study, we immunostained 30 biopsy samples of SCLC with antibodies to hypoxia inducible factor-1 alpha (HIF-1 alpha), vascular endothelial growth factor (VEGF), vascular endothelial growth factor-receptor 1 (VEGF-R1/flt-1) and vascular endothelial growth factor-receptor 2 (VEGF-R1/flk-1). The immunoreactivity was analyzed using a bivariate Spearman correlation test and linear regression analysis. We found significant correlation between HIF-1 alpha nuclear staining and VEGF staining. Moreover HIF-1 alpha+/VEGF+ cases were associated with poor survival. We also found a positive correlation between VEGF and VEGF-R2 expression. We suggest that a HIF-1 alpha/VEGF angiogenic pathway may exist in vivo in SCLC, similar to that in non-SCLC. Our data also suggest a potential VEGF/VEGFR-2 autocrine pathway in SCLC. The inclusion of novel inhibitors to HIF-1 alpha and other factors may optimize antiangiogenic interventions in SCLC.

Current status of second-line treatment and novel therapies for small cell lung cancer

Despite high response rates to first-line standard treatment, the great majority of patients with small cell lung cancer (SCLC) will relapse and succumb to their disease rather quickly. In the context of salvage therapy, symptom palliation and quality-of-life improvements, besides survival prolongation, are primary treatment endpoints. A variety of single-agent and multi-agent chemotherapy regimens have been tested with limited success in patients with recurrent SCLC. A number of combination regimens have demonstrated high response rates in second-line settings, but these can be considered only for patients with good performance status. Treatment outcome depends on many factors, including type of response to first-line therapy, treatment-free interval, and performance status. Currently, topotecan represents an effective, tolerable therapeutic option and is the only agent approved for this indication. The management of patients with recurrent disease remains an area of active research. This review provides an update of clinical research on second-line chemotherapy of SCLC and of recent results obtained with novel molecular targeted approaches in both first- and second-line therapy.

[Small-cell carcinoma of the vulva]

Small-cell carcinoma is a rare and aggressive malignancy; this tumor is lethal due to the propensity to metastasize early in the course of the disease. It occurs most frequently in the lung. Small-cell cancer also rarely may occur in the female genital tract, usually in the cervix. This article concerns the fifth reported case of small-cell carcinoma of the vulva in a 34-year-old women who had developed a vulvar mass3 months earlier. The physical examination revealed bilateral inguinal lymph nodes. The mass was excised and the histological finding was a small-cell carcinoma. Postoperative search for metastasis included computed tomography scan of the abdomen, pelvis, chest and brain that showed right iliac lymph nodes. The osteo medullar biopsy was positive. The patient was treated with 6 cycles of chemotherapy including cisplatinum (80mg/m2 d1) and etoposide (100mg/m2 d1 d2 d3). Adjuvant radiotherapy (50Gy) was administered but the disease progressed and the patient died after 7 months. Small-cell carcinoma of the vulva is a very rare tumor. Similarly to small-cell cancers arising in other sites, it appears that regional therapy is not a sufficient treatment for this tumor. Chemotherapy should be used to improve outcome.

Clinical review – Small cell carcinoma of the bladder

OBJECTIVES

To review the published literature on the diagnosis and management of small cell carcinoma of the bladder (SCCB).

METHODS

Papers were identified by searches of PubMed using the terms "small cell", "bladder" and "carcinoma". Additional papers were identified from review of references of relevant articles.

RESULTS

SCCB comprises less than 1% of bladder malignancies. It is an aggressive tumour that commonly presents at an advanced stage, in an elderly population. Consequently, patients are often not fit for anti-neoplastic therapy. In fit patients, the bedrock of treatment in the majority of cases is platinum-based systemic chemotherapy, which was the only factor predictive of improved outcome on multivariate analysis in one large review. The use of neoadjuvant chemotherapy has been associated with favourable results and may therefore be the preferred approach when scheduling treatment. Options for local management comprise surgery or radiotherapy (sequentially or concurrently with chemotherapy), both of which are potentially curative in selected cases. However, the subsequent frequent development of urothelial malignancies with bladder-sparing approaches should be considered when planning treatment, particularly in younger patients. Prognosis of SCCB overall is poor, the median survival of all cases varies from 4 to 23 months, and overall survival at 5 years from 10% to 40% of patients.

CONCLUSIONS

SCCB is a rare and aggressive tumour with a poor prognosis. Future efforts should be directed at its early detection and the development of more effective systemic therapies.

AQUA and FISH analysis of HER-2/neu expression and amplification in a small cell lung carcinoma tissue microarray

AIMS

Most small cell lung carcinoma (SCLC) patients have metastatic disease at the time of diagnosis and are faced with poor prognosis and limited treatment options. Reports of HER-2/neu gene amplification and overexpression in this malignancy have raised the possibility of applying targeted immunotherapy with trastuzumab, the monoclonal antibody used to treat metastatic breast cancer. However, a review of the studies measuring HER-2/neu gene amplification and protein expression in SCLC reveals discordant results. The aim of the present study was to re-examine HER-2/neu expression in SCLC in relation to gene copy number using the new, highly sensitive, immunofluorescence automated quantitative analysis (AQUA) technology.

METHODS AND RESULTS

Fluorescence in situ hybridization (FISH) was used to measure HER-2/neu gene copy number and amplification status and AQUA was used to measure protein expression in a series of 23 SCLC tumours on a tissue microarray. None of the 17 SCLC specimens assessable by FISH exhibited HER-2/neu gene amplification as defined by a HER-2/neu/chromosome 17 ratio = or > 2. Twelve of 17 (70.1%) SCLC samples were polysomic for chromosome 17 with corresponding increases in HER-2/neu gene copy numbers. Intermediate levels of protein expression corresponding to AQUA scores in the range of 4-24 were detected in all 23 specimens. High protein expression levels corresponding to AQUA scores up to 83, observed previously in association with gene amplification and poor prognosis in breast cancer cases, were not detected in the present study. No statistically significant association was observed between absolute chromosome 17 or HER-2/neu gene copy numbers and protein expression levels in tumour cells (P > 0.45).

CONCLUSIONS

The lack of gene amplification and robust HER-2/neu protein expression in SCLC tumour cells in this series does not suggest a prominent role for the HER-2/neu gene in SCLC tumour progression and does not support the general applicability of targeted immunotherapy with trastuzumab to this malignancy.

Treatment of Small Cell Lung Cancer in the Elderly

Small cell lung cancer (SCLC) accounts for approximately 20% of lung carcinomas. Chemotherapy is the cornerstone of treatment for SCLC. In limited disease, the median survival time is about 12-16 months, with a 4%-5% long-term survival rate; in extensive disease the median survival time is 7-11 months. More than 50% of lung cancer patients are diagnosed when they are over the age of 65, and about 30% are over 70. Elderly patients tolerate chemotherapy poorly compared with their younger counterparts, because of age-related progressive reductions in organ function and comorbidities. The standard therapy for limited disease is combined chemoradiotherapy, followed by prophylactic brain irradiation for patients achieving complete responses. In the elderly, the addition of radiotherapy to chemotherapy must be carefully evaluated, considering the slight survival benefit and potential for substantial toxicity incurred with this treatment. The best approach is to design clinical trials that specifically include geriatric assessment to develop active and well-tolerated chemotherapy regimens for elderly SCLC patients. Survival improvement for SCLC patients requires a better understanding of tumor biology and the subsequent development of novel therapeutic strategies. Several targeted agents have been introduced into clinical trials in SCLC, but a minority of these new agents offers a promise of improved outcomes, and negative results are reported more commonly than positive ones. This review focuses on the main issues in the treatment of elderly SCLC patients.

Therapy, outcome and analysis of c-kit expression in patients with extrapulmonary small cell carcinoma

In this study, we aimed to investigate the clinicopathological characteristics with special emphasis on c-kit expression and the treatment results of patients with extrapulmonary small cell carcinoma (EPSCC). The medical records of the patients with EPSCC were reviewed, and the data regarding patient and tumour characteristics, treatment and clinical outcome were retrieved and analysed. A total of 28 patients with the diagnosis of EPSCC were identified. There were 19 males and 9 females, with a mean age of 56.5 years. Patients with limited disease (LD) (n = 13) were treated with surgery, chemotherapy (CT) and radiotherapy with different sequences. Patients with extensive disease (ED) (n = 15) were mainly treated with combination CT. The median overall survival was 14.5 months in patients with LD compared to 11 months in those with ED (p = 0.029). Ten patients (36%) showed c-kit overexpression. There was no significant difference between the survival of c-kit-positive and c-kit-negative patients (p = 0.367). In conclusion, our study demonstrates that the prognosis of EPSCC is poor despite currently available treatments. C-kit may be considered as a potential target for novel therapeutical approaches.

Identification of the 'NORE' (N-Oct-3 responsive element), a novel structural motif and composite element

N-Oct-3 is a neuronal transcription factor widely expressed in the developing mammalian central nervous system, and necessary to maintain neural cell differentiation. The key role of N-Oct-3 in the transcriptional regulation of a multiplicity of genes is primarily due to the structural plasticity of its so-called ‘POU’ (acronym of Pit, Oct, Unc) DNA-binding domain. We have recently reported about the unusual dual neuro-specific transcriptional regulation displayed by N-Oct-3 [Blaud,M., Vossen,C., Joseph,G., Alazard,R., Erard,M. and Nieto,L. (2004) J. Mol. Biol., 339, 1049–1058]. To elucidate the underlying molecular mechanisms, we have now made use of molecular modeling, DNA footprinting and electrophoretic mobility shift assay techniques. This combined approach has allowed us to uncover a novel mode of homodimerization adopted by the N-Oct-3 POU domain bound to the neuronal aromatic amino acids de-carboxylase and corticotropin-releasing hormone gene promoters and to demonstrate that this pattern is induced by a structural motif that we have termed ‘NORE’ (N-Oct-3 responsive element), comprising the 14 bp sequence element TNNRTAAATAATRN. In addition, we have been able to explain how the same structural motif can also induce the formation of a heterodimer in association with hepatocyte nuclear factor 3β(/Forkhead box a2). Finally, we discuss the possible role of the NORE motif in relation to neuroendocrine lung tumor formation, and in particular the development of small cell lung cancer.