Adjuvant chemotherapy for early-stage non-small cell lung cancer: the past, the present and the future

Prognostic potential of FOXP3 expression in non-small cell lung cancer cells combined with tumor-infiltrating regulatory T cells

Expression of the transcription factor FOXP3 characterizes regulatory T cells (Tregs) that engage in the maintenance of immunological self-tolerance and immune homeostasis. Intra-tumoral accumulation of Tregs is associated with unfavorable prognosis in several kinds of cancers. Recently, expression of FOXP3 and its association with prognosis have also been shown in some cancer cells in clinical studies. For non-small cell lung cancer (NSCLC), however, prognostic significance of tumor FOXP3 expression and its relationship with Tregs remain unknown. FOXP3 expression in cancer cells and tumor-infiltrating lymphocytes was examined by immunohistochemical staining of surgical specimens from 87 patients with NSCLC. Prognostic values of the tumor-infiltrating Treg count and tumor FOXP3 expression status were evaluated retrospectively. FOXP3-positive cancer cells were observed in 27 of 87 (31.0%) patients. There was no significant relationship between Treg count and tumor FOXP3 status. Increased Treg counts were associated with worse overall and relapse-free survival whereas the influence of tumor FOXP3 status on survival was not significant. However, when FOXP3-positive cancer cells were present, the relationship between Treg accumulation and worse prognosis was attenuated. In contrast, patients without tumor FOXP3 expression and high Treg count had significantly worse overall and relapse-free survival (hazard ratio: 3.118 and 3.325, p=0.028 and 0.024, respectively) than other groups. These results suggest that tumor FOXP3 expression has a better prognostic potential in NSCLC and that in combination with tumor-infiltrating Treg count the absence of tumor FOXP3 allows the selection of high-risk patients.

Stimulatory heterotrimeric G protein augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 human lung cancer cells

Stimulatory heterotrimeric GTP-binding proteins (Gs protein) stimulate cAMP generation in response to various signals, and modulate various cellular phenomena such as proliferation and apoptosis. This study aimed to investigate the effect of Gs proteins on gamma ray-induced apoptosis of lung cancer cells and its molecular mechanism, as an attempt to develop a new strategy to improve the therapeutic efficacy of gamma radiation. Expression of constitutively active mutant of the alpha subunit of Gs (GalphasQL) augmented gamma ray-induced apoptosis via mitochondrial dependent pathway when assessed by clonogenic assay, FACS analysis of PI stained cells, and western blot analysis of the cytoplasmic translocation of cytochrome C and the cleavage of caspase-3 and ploy(ADP-ribose) polymerase (PARP) in H1299 human lung cancer cells. GalphasQL up-regulated the Bak expression at the levels of protein and mRNA. Treatment with inhibitors of PKA (H89), SP600125 (JNK inhibitor), and a CRE-decoy blocked GalphasQL-stimulated Bak reporter luciferase activity. Expression of GalphasQL increased basal and gamma ray-induced luciferase activity of cAMP response element binding protein (CREB) and AP-1, and the binding of CREB and AP-1 to Bak promoter. Furthermore, prostaglandin E2, a Galphas activating signal, was found to augment gamma ray-induced apoptosis, which was abolished by treatment with a prostanoid receptor antagonist. These results indicate that Galphas augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 lung cancer cells, suggesting that the efficacy of radiotherapy of lung cancer may be improved by modulating Gs signaling pathway.

How regulatory CD25+CD4+ T cells impinge on tumor immunobiology: the differential response of tumors to therapies

Aiming to get a better insight on the impact of regulatory CD25(+)CD4(+) T cells in tumor-immunobiology, a simple mathematical model was previously formulated and studied. This model predicts the existence of two alternative modes of uncontrolled tumor growth, which differ on their coupling with the immune system, providing a plausible explanation to the observation that the development of some tumors expand regulatory T cells whereas others do not. We report now the study of how these two tumor classes respond to different therapies, namely vaccination, immune suppression, surgery, and their different combinations. We show 1) how the timing and the dose applied in each particular treatment determine whether the tumor will be rejected, with or without concomitant autoimmunity, or whether it will continue progressing with slower or faster pace; 2) that both regulatory T cell-dependent and independent tumors are equally sensitive to vaccination, although the former are more sensitive to T cell depletion treatments and are unresponsive to partial surgery alone; 3) that surgery, suppression, and vaccination treatments, can synergistically improve their individual effects, when properly combined. Particularly, we predict rational combinations helping to overcome the limitation of these individual treatments on the late stage of tumor development.

Inhibition by erlotinib of primary lung adenocarcinoma at an early stage in male mice

PURPOSE

Erlotinib, a small molecule inhibitor of the tyrosine kinase (TK) domain of epidermal growth factor receptor (EGFR), increases survival of advanced non-small cell lung cancer patients who failed standard chemotherapy (Phase III study). We evaluated whether erlotinib is also effective at an early stage of primary lung tumorigenesis in a carcinogen-induced lung tumor model in mice.

METHODS

Sixteen weeks after carcinogen (urethane) injection, when small self-contained adenomas are evident, male and female A/J mice were treated IP with 10 mg/kg erlotinib or Captisol vehicle daily over 3.5 weeks (15 mice per group). The efficacy, metabolism and mechanism of action of erlotinib were evaluated.

RESULTS

Erlotinib reduced tumor burden in males by twofold compared to vehicle (12.7 +/- 1.2 vs 26.2 +/- 2.5 mg, respectively; p < 0.0001), while tumor burden in erlotinib-treated females slightly increased compared to vehicle by 21% (15.1 +/- 1.2 vs 11.9 +/- 0.9 mg, respectively; p < 0.05). Tumor multiplicity, in contrast, was unaffected by erlotinib. The levels of erlotinib that accumulated in plasma, lung tumor tissue and adjacent uninvolved (UI) lung were comparable in males and females. Males, however, accumulated more OSI-420, an active and pharmacologically equipotent metabolite of erlotinib, than females in plasma, lung tumors, and UI lung. In both genders, 80% of tumors contained Kras mutations at codon 61, but no EGFR mutations were detected. The cellular distribution and concentration of EGFR were also similar between genders. In control mice, however, phosphorylated EGFR (pEGFR) levels were nearly 2.5-fold higher in males compared to females in UI lungs and sevenfold higher in lung tumors. Further, erlotinib decreased the contents of pEGFR in UI lungs and lung tumors, particularly in males.

CONCLUSIONS

Adenomas from male mice in this early lung cancer model are responsive to erlotinib treatment, possibly because of a greater dependence of male tumor growth on the EGFR pathway compared to females. Importantly, these results indicate that small lung adenomas from male mice that utilize EGFR signaling but also harbor Kras mutations shrink in response to erlotinib, suggesting that erlotinib may be beneficial for some patients very early during lung cancer progression.