Human small-cell lung-cancer cells are cytokine-resistant but NK/LAK-sensitive

Overcoming chemoresistance of small-cell lung cancer through stepwise HER2-targeted antibody-dependent cell-mediated cytotoxicity and VEGF-targeted antiangiogenesis

Small-cell lung cancer (SCLC) easily recurs with a multidrug resistant phenotype. However, standard therapeutic strategies for relapsed SCLC remain unestablished. We found that human epidermal growth factor receptor 2 (HER2) is not only expressed in pretreated human SCLC specimens, but is also upregulated when HER2-positive SCLC cells acquire chemoresistance. Trastuzumab induced differential levels of antibody-dependent cell-mediated cytotoxicity (ADCC) to HER2-positive SCLC cells. Furthermore, as a mechanism of the differential levels of ADCC, we have revealed that coexpression of intracellular adhesion molecule (ICAM)-1 on SCLC cells is essential to facilitate and accelerate the trastuzumab-mediated ADCC. Although SN-38-resistant SCLC cells lacking ICAM-1 expression were still refractory to trastuzumab, their in vivo growth was significantly suppressed by bevacizumab treatment due to dependence on their distinctive and abundant production of vascular endothelial growth factor. Collectively, stepwise treatment with trastuzumab and bevacizumab is promising for the treatment of chemoresistant SCLC.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

Targeted therapies in small-cell lung cancer

Small-cell lung cancer is an aggressive form of lung cancer that, overall, remains the most common cause of cancer death in the US. Some advances have been made in the treatment of small-cell lung cancer using cytotoxic chemotherapeutic agents but no truly targeted therapies are available as of yet. At present, research is focused on finding therapies that can target the specific molecular mechanisms responsible for the survival, growth and metastasis of the tumor thereby improving responses to chemotherapy and minimizing toxicity. Several new agents, such as angiogenesis inhibitors and regulators of apoptosis, have reached clinical testing and multiple others are in preclinical trials. Some of these will be discussed in this review.

Mammalian thioredoxin reductase alters cytolytic activity of an antibacterial peptide

Granulysin is a disulfide rich 9 kDa human tumoricidal protein produced by cytolytic cells. Here we show that thioredoxin reductase (TrxR) reduced a 23-residue peptide from granulysin (GranF2), and this markedly enhanced the killing of small cell lung cancer cells (SCLC) by GranF2. Cells treated with reduced GranF2 showed rapid ATP deletion within 90 min and strong annexin V staining after 4 h incubation. SCLC with elevated TrxR levels was more sensitive to oxidized GranF2 than normal cells. The levels of TrxR are enhanced in many cancer cells, including SCLC, and it is possible that cytolytic activity of cytolytic cells on SCLC may in part be mediated by granulysin and modulated by TrxR.

Lack of correlation between growth inhibition by TGF-beta and the percentage of cells expressing type II TGF-beta receptor in human non-small cell lung carcinoma cell lines

To determine the mechanisms involved in the evasion from TGF-beta growth regulation in the small cell lung carcinoma (SCLC) cell lines and the non-small cell lung carcinoma (NSCLC) cell lines, we studied: (a) production of TGF-beta1 and TGF-beta2; (b) percentage of cells expressing TGF-beta RII; (c) responsiveness of the tumour cell lines to exogenous TGF-beta1 or TGF-beta2; and (d) presence of mRNA transcripts of the three TGF-beta isoforms and of the TGF-beta RII. Our results indicate that the SCLC cell lines do not synthesize the isoforms TGF-beta1 and TGF-beta2 nor the TGF-beta RII, thus avoiding inhibitory autocrine and paracrine TGF-beta actions. However, NSCLC cell lines express not only TGF-beta1, TGF-beta2 and TGF-beta RII mRNA transcripts, but also synthesize both isoforms and the TGF-beta RII. Although approximately 50% of the cells from the studied cell lines expressed the TGF-beta RII, different cell lines varied greatly in the sensitivity to the inhibitory action of TGF-beta. This could result from alterations in: (i) the structure of TGF-beta RII; (ii) the phosphorylation motif of TGF-beta RI; (iii) the molecules involved in the intracellular signalling pathway of TGF-beta; and (iv) cell cycle regulation.

Adenovirus vector-mediated transfer of 9 kDa granulysin induces DNA fragmentation in HuD antigen-expressing small cell lung cancer murine model cells

OBJECTIVE

Granulysin is a tumoricidal molecule secreted by cytotoxic T cells (CTL) and natural killer (NK) cells, that induces apoptotic cell death in tumour cells. It has been demonstrated that small cell lung cancer (SCLC) cell lines are susceptible to NK cells and lymphokine activated killer (LAK) cells, and HuD antigen is assumed to be a target molecule on SCLC cells for host cellular immunity.

METHODOLOGY

In order to understand the mechanism of sensitivity of SCLC to cellular immunity, we evaluated granulysin-induced apoptosis using mouse adenocarcinoma Colon 26 (Colon 26/HuD) cells transfected with the 9 kDa active form of granulysin using an adenovirus vector as a murine model of SCLC cells.

RESULTS

Adenovirus vector-mediated transfer of 9 kDa granulysin increased DNA fragmentation in Colon 26/HuD cells 2.5-fold and suppressed Colon 26/HuD proliferation by 21% on day 3 (P < 0.05 for each value) compared with the control adenovirus vector transfer. In contrast, adenovirus vector-mediated transfer of 9 kDa granulysin did not increase DNA fragmentation nor suppress the proliferation of Colon 26 parent cells.

CONCLUSIONS

The sensitivity of HuD-expressing tumour cells to granulysin is likely to partially explain the susceptibility of SCLC to cell-mediated immunity.

Interferon alpha-2a and combined chemotherapy as first line treatment in SCLC patients: a randomized trial

BACKGROUND

Interferons (IFNs) are known to act synergistically with antineoplastic agents when applied to SCLC cell cultures. This study was conducted in order to detect the clinical benefits, if any, of the addition of IFN-alpha in the induction chemotherapy (CT) of SCLC patients.

PATIENTS AND METHODS

Ninety previously untreated patients with SCLC were randomly assigned to receive either CT alone (arm A) or CT plus IFN alpha-2a in a dose of 3 MU/m2 twice weekly (arm B). CT for both arms consisted of carboplatin 420 mg/m2, etoposide 200 mg/m2 and ifosfamide 3.5 g/m2 or epirubicin 80 mg/m2 every 28 days for a total of eight cycles. Responding patients received primary site and prophylactic cranial irradiation and then had maintenance CT with cyclophosphamide 100 mg/m2/day for 20 days every month. Patients in arm B received IFN throughout these treatments.

RESULTS

Eighty-one patients were evaluable for response, 39 in arm A and 42 in arm B. Both arms were comparable in terms of age, performance status and extent of disease. Overall response rates were not significantly different between the two arms (90% vs. 86%), although complete response rate was higher in arm B (38% vs. 28%). More importantly, Kaplan-Meier analysis disclosed a clear survival benefit in the arm receiving IFN-alpha (P < 0.05). For limited disease the difference was even more significant (P < 0.0067), while for extensive disease no significant difference was found (P < 0.35). Fever, fatigue and anorexia were more frequent in arm B (P < 0.001), as also leukopenia (P < 0.01).

CONCLUSION

The addition of IFN-alpha to induction CT appears to confer a survival benefit to SCLC patients but optimal dosing schedule has yet to be defined.

Pretreatment fibrinogen levels are associated with response to chemotherapy in patients with small cell carcinoma of the lung: Department of Veterans Affairs Cooperative Study 188

Small cell carcinoma of the lung (SCCL) responds commonly to combination chemotherapy but resistance to therapy follows. Prior reports have suggested that a relationship may exist between plasma fibrinogen levels and response to therapy in SCCL. This study was designed to determine the possible predictive value of the fibrinogen level for tumor response (chemoresistance) in SCCL. Pretreatment fibrinogen levels were correlated with outcome and response to therapy in a cohort of 119 previously untreated patients with SCCL who were admitted to VA Cooperative Study 188. Higher pretreatment fibrinogen levels at diagnosis correlated significantly with more advanced stage of disease at entry (P < 0.001) and with reduced overall survival (P = 0.030). In addition, higher pretreatment fibrinogen levels were correlated significantly with a reduced likelihood of achieving subsequent disease regression with combination chemotherapy (P = 0.005). Because several clinical trials have shown that anticoagulant therapy improves tumor response rates and survival of SCCL, we postulate that tumor cell thrombin generation not only promotes SCCL growth but may also be primarily responsible for both increased fibrinogen levels and for resistance to chemotherapy. These findings provide incentive for studies of thrombin effects on the development of multidrug resistance, and for new clinical trials of more potent and specific inhibitors of thrombin that may further improve tumor response and survival in SCCL.

Expression of transforming growth factor-beta 1 in human bladder cancer

BACKGROUND

Elevated expression of transforming growth factor-beta 1 (TGF-beta 1) has been reported in several types of human cancer. However, the significance of TGF-beta 1 expression in clinical bladder cancer is not well known.

METHODS

The levels of TGF-beta 1 expression were quantitated using a polymerase chain reaction-based method in tissue specimens obtained from 51 patients with bladder cancer.

RESULTS

Transforming growth factor-beta 1 expression in bladder cancer was higher than that found in normal bladder epithelium (P < 0.01). Significantly higher levels of TGF-beta 1 transcripts were observed in low and intermediate grade (Grade 1 and 2) tumors than in high grade (Grade 3) tumors (P < 0.02). Superficial (pTa and pT1) tumors had higher levels of TGF-beta 1 than invasive (pT2 or higher) tumors (P < 0.05).

CONCLUSIONS

These results suggest that enhanced expression of TGF-beta 1 is specific to low grade and stage bladder cancer. Transforming growth factor-beta 1 may play an important role in the early stages of human bladder cancer development, and TGF-beta 1 expression could provide a new relevant tumor marker for determining tumor progression in patients with bladder cancer.

Antiproliferative and recovery effects during treatment of breast and ovarian carcinoma cell cultures with interferon-gamma

We studied the antiproliferative effects of human interferon-gamma (IFN-gamma) on cell lines derived from human carcinomas (three breast, two ovarian, and one renal) and recovery from these effects when IFN-gamma was removed after 6 or 72 h. IFN-gamma led to a dose-dependent and time-dependent cytostatic inhibition of all six tumor cell lines; the renal carcinoma cells were by far the most sensitive, and with these, cytotoxic effects were also seen. The 50% inhibitory dose (ID50) for each cell line was different and remarkably constant over many months. When cells were exposed to IFN-gamma for only 9 or 72 h, those from three lines recovered completely from the growth inhibitory effects, but from three only partially. When cultured for several weeks in the presence of 1600 U/ml of IFN-gamma, two lines developed increased resistance to IFN-gamma, one became much less sensitive, and two showed no changes in sensitivity. We saw no correlations between these changes during continuous exposure to IFN-gamma and the antiproliferative ID50 for each cell or whether the cells recovered completely from the inhibitory effects of IFN-gamma after short-term exposure. Nevertheless, cells with a population doubling time of less than 48 h had low to moderate sensitivity to IFN-gamma and seemed to recover more completely than those doubling in more than 61 h. Our results indicate great individual variation in the in vitro sensitivity of carcinoma cells to the antiproliferative effects of IFN-gamma.

Growth suppression by transforming growth factor beta 1 of human small-cell lung cancer cell lines is associated with expression of the type II receptor

Nine human small-cell lung cancer cell lines were treated with transforming growth factor beta 1 (TGF-beta 1). Seven of the cell lines expressed receptors for transforming growth factor beta (TGF-beta-r) in different combinations between the three human subtypes I, II and III, and two were receptor negative. Growth suppression was induced by TGF-beta 1 exclusively in the five cell lines expressing the type II receptor. For the first time growth suppression by TGF-beta 1 of a cell line expressing the type II receptor without coexpression of the type I receptor is reported. No effect on growth was observed in two cell lines expressing only type III receptor and in TGF-beta-r negative cell lines. In two cell lines expressing all three receptor types, growth suppression was accompanied by morphological changes. To evaluate the possible involvement of the retinoblastoma protein (pRb) in mediating the growth-suppressive effect of TGF-beta 1, the expression of functional pRb, as characterised by nuclear localisation, was examined by immunocytochemistry. Nuclear association of pRb was only seen in two of the five TGF-beta 1-responsive cell lines. These results indicate that in SCLC pRb is not required for mediation of TGF-beta 1-induced growth suppression.

Interferon-gamma-induced increased sensitivity of HER2/neu-overexpressing tumor cells to lymphokine-activated killer cell lysis: importance of ICAM-1 in binding and post-binding events

Treatment of HER2/neu-overexpressing target cells with interferon gamma (IFN gamma) (200-2000 U/ml for 3 days) markedly enhances their sensitivity to lymphokine-activated killer (LAK) cell lysis. Increased sensitivity is associated with an up-regulation of intercellular adhesion molecule ICAM-1 determinants and a down-regulation of HER2/neu expression. In the present study, we show that exposure to another cytokine, tumor necrosis factor alpha (200 U/ml for 3 days), also decreased HER2/neu expression but had no effect on LAK cell lysis and ICAM-1 expression. This suggests that down-regulation of oncogene expression is not sufficient by itself to induce an enhanced sensitivity to LAK cell lysis. IFN-induced enhanced lysis was associated with an increased binding between effectors and targets, and antibodies to ICAM-1 as well as its counter-receptor LFA-1, blocked the increased binding and lysis. Treatment with IFN gamma still significantly enhanced lysis even when concanavalin A was added to the assay to induce maximal binding, indicating that a post-binding effect also participated in enhanced cytotoxicity. These post-binding alterations, were also sensitive to blocking with anti-ICAM-1 and anti-LFA-1 antibodies. Treatment with IFN also sensitized targets to lysis by T cells in the presence of lectin but had no effect on the relative resistance of HER2+ cells to lysis mediated by perforin or TNF. Together these data demonstrate the importance of ICAM-1 determinants in binding and post-binding events in the IFN-induced increased lysis of HER2/neu+ targets.

Expression of transforming growth factor beta (TGF beta) receptors and expression of TGF beta 1, TGF beta 2 and TGF beta 3 in human small cell lung cancer cell lines

A panel of 21 small cell lung cancer cell (SCLC) lines were examined for the presence of Transforming growth factor beta receptors (TGF beta-r) and the expression of TGF beta mRNAs. By the radioreceptor assay we found high affinity receptors to be expressed in six cell lines. scatchard analysis of the binding data demonstrated that the cells bound between 4.5 and 27.5 fmol mg-1 protein with a KD ranging from 16 to 40 pM. TGF beta 1 binding to the receptors was confirmed by cross-linking TGF beta 1 to the TGF beta-r. Three classes of TGF beta-r were demonstrated, type I and type II receptors with M(r) = 65,000 and 90,000 and the betaglycan (type III) with M(r) = 280,000. Northern blotting showed expression of TGF beta 1 mRNA in ten, TGF beta 2 mRNA in two and TGF beta 3 mRNA in seven cell lines. Our results provide, for the first time, evidence that a large proportion of a broad panel of SCLC cell lines express TGF beta-receptors and also produce TGF beta mRNAs.

High sensitivity to peripheral blood lymphocytes and low HLA-class I antigen expression of small cell lung cancer cell lines with diverse chemo-radiosensitivity

Three cell lines of small cell lung cancer (SCLC), which were established from specimens of untreated primary tumors biopsied by diagnostic bronchofiberscopy, were analyzed for immunological characteristics. These cell lines showed considerable heterogeneity in chemo-radiosensitivity, which was well correlated with clinical responses of the respective tumors, but their HLA-class I antigen expressions were equally depressed and they were susceptible to peripheral blood lymphocytes (PBL) and lymphokine-activated killer (LAK) cells, irrespective of their diverse chemo-radiosensitivity. Treatment of the cell lines with recombinant immune interferon (rIFN-gamma) increased their HLA-class I antigen expression and conversely depressed PBL sensitivity but not LAK sensitivity. This inverse relationship between HLA-class I expression and PBL susceptibility was also demonstrated using other pairs of autologous PBL and SCLC cell lines. rIFN-gamma changed neither HLA-class II antigen nor SCLC-specific antigen expression under the same experimental conditions. In vitro immunization of allogeneic peripheral blood lymphocytes with rIFN-gamma-treated SCLC cells induced allo-specific killer cells which lysed rIFN-gamma-treated more strongly than non-treated SCLC cells. These results suggest that reduced HLA-class I antigen expression of SCLC could protect the cancer from attack of killer T cells in spite of the higher sensitivity to PBL or LAK cells.