15-Lipoxygenase-1 induced by interleukin-4 mediates apoptosis in oral cavity cancer cells

IL-13 and the hydroperoxy fatty acid 13(S)HpODE play crucial role in inducing an apoptotic pathway in cancer cells involving MAO-A/ROS/p53/p21 signaling axis

This study depicted the effect of IL-13 and 13(S)HpODE (the endogenous product during IL-13 activation) in the process of cancer cell apoptosis. We examined the role of both IL-13 and 13(S)HpODE in mediating apoptotic pathway in three different in vitro cellular models namely A549 lung cancer, HCT116 colorectal cancer and CCF52 GBM cells. Our data showed that IL-13 promotes apoptosis of A549 lung carcinoma cells through the involvement of 15-LO, PPARγ and MAO-A. Our observations demonstrated that IL-13/13(S)HpODE stimulate MAO-A-mediated intracellular ROS production and p53 as well as p21 induction which play a crucial role in IL-13-stimulated A549 cell apoptosis. We further showed that 13(S)HpODE promotes apoptosis of HCT116 and CCF52 cells through the up-regulation of p53 and p21 expression. Our data delineated that IL-13 stimulates p53 and p21 induction which is mediated through 15-LO and MAO-A in A549 cells. In addition, we observed that PPARγ plays a vital role in apoptosis as well as in p53 and p21 expression in A549 cells in the presence of IL-13. We validated our observations in case of an in vivo colon cancer tumorigenic study using syngeneic mice model and demonstrated that 13(S)HpODE significantly reduces solid tumor growth through the activation of apoptosis. These data thus confirmed that IL-13 > 15-LO>13(S)HpODE > PPARγ>MAO-A > ROS > p53>p21 axis has a major contribution in regulating cancer cell apoptosis and further identified 13(S)HpODE as a potential chemo-preventive agent which can improve the efficacy of cancer treatment as a combination compound.

Specific overexpression of 15-lipoxygenase in endothelial cells promotes cancer cell death in an in vivo Lewis lung carcinoma mouse model

PURPOSE

Lipoxygenases (LOX) have been implicated in carcinogenesis, however both pro- and anti-carcinogenic effects have been reported in different cancer models. Using transgenic mice, which specifically overexpress human 15-lipoxygenase (ALOX15) in endothelial cells (EC), we previously demonstrated significant inhibition of tumor development. In the Lewis lung carcinoma (LLC) model, the primary tumor developed similarly in both wild type (WT) and ALOX15 overexpressing mice. However, metastases development was significantly inhibited in the transgenic mice. Here, we explored the molecular basis for the anti-metastatic effect of endothelial cell specific ALOX15 overexpression.

MATERIALS/METHODS

We used ALOX15 overexpressing mice, and in-vitro cell model to evaluate the molecular effect of ALOX15 on EC and LLC cells.

RESULTS

When LLC cells were injected in WT and ALOX15 overexpressing mice, we observed a higher degree of apoptosis and necrosis in primary and metastatic tumors of ALOX15 overexpressing animals. These anti-carcinogenic and anti-metastatic effects were paralleled by augmented expression of cyclin-dependent kinase inhibitor 1A (CDKN1A; p21) and of the peroxisome proliferators-activated receptor (PPAR)γ and by downregulation of the steady state concentrations of connexin26 mRNA. Consistent with these in vivo effects, ALOX15 overexpression in LLC and HeLa cancer cells in vitro significantly reduced cell viability in culture. In contrast, similar treatment of non-cancerous B2B epithelial cells did not impact cell viability.

CONCLUSIONS

Taken together, our data suggests that endothelial cell specific overexpression of ALOX15 promotes apoptosis and necrosis in primary and metastatic tumors in mice, by upregulation of P21 and PPARγ expression in adjacent cancer cells.

A high IL-4 production diplotype is associated with an increased risk but better prognosis of oral and pharyngeal carcinomas

OBJECTIVE

Interleukin (IL)-4 is a key cytokine in humoral and adaptive immunity. This study aimed to evaluate the association of IL-4 genetic variants (-590C>T and VNTR in intron 3) with the risk and prognosis of oral and pharyngeal squamous cell carcinoma (OPSCC).

DESIGN

A total of 1215 subjects, which included 623 healthy controls and 592 OPSCC cases (463 oral squamous cell carcinoma (OSCC) and 129 pharyngeal squamous cell carcinoma (PSCC) cases), were recruited. The genotypes were determined by TaqMan real-time assay and PCR-based assay.

RESULTS

The IL-4 genotypes at locus -590C>T and intron 3 VNTR were not correlated with increased risk of OSCC, PSCC, and OPSCC, with the exception of early-stage OPSCC (at -590C>T: T/T vs. C/C+C/T, adjusted odds ratio (AOR)=1.42, 95% CI: 1.02-1.98; at intron 3 VNTR: RP1/RP1 vs. RP2/RP2+RP2/RP1, AOR=1.46, 95% CI: 1.05-2.04). Compared with other IL-4 diplotypes, the T,RP1/T,RP1 diplotype was associated with an increased risk of OPSCC (AOR=1.37, 95% CI: 1.03-1.81), particularly early-stage OSCC (AOR=1.43, 95% CI: 1.02-2.00), PSCC (AOR=2.35, 95% CI: 1.06-5.19), and OPSCC (AOR=1.52, 95% CI: 1.10-2.11). Interactions between the IL-4 diplotype and the alcohol drinking status were found to contribute to the risk of early-stage OPSCC (p=0.024). In addition, the T,RP1/T,RP1 diplotype was correlated with better disease-specific survival (T,RP1/T,RP1 vs. other diplotypes, adjusted hazard ratio=0.70, 95% CI: 0.50-0.97).

CONCLUSION

The T, RP1/T, RP1 diplotype of IL-4 was associated with an increased risk but favourable prognosis of OPSCC.

Induction of apoptosis by Trichostatin A in human breast cancer cell lines: involvement of 15-Lox-1

15-Lipoxygenase-1 (15-Lox-1) is a key enzyme mediating oxidative metabolism of polyunsaturated fatty acids and has attracted considerable interest as a potential target for the induction of apoptosis in cancer cells. Knowledge of relationship between 15-Lox-1 and histone deacetylase inhibitors is lacking in the breast cancer. This study is aimed to investigate the role of Trichostatin A (TSA) and 13(S)-HODE, as a metabolite of 15-Lox-1, in the regulation of breast cancer cell growth. The cytotoxic effect of TSA, as a potent HDAC inhibitor, was measured using MTT assay. Annexin V-FITC and PI staining were performed to detect apoptosis and cell cycle distribution using Flow cytometry. The role of 15-Lox-1 in the regulation of cell growth was assessed by 15-Lox-1 inhibitor and the level of 15-Lox-1 metabolite was measured to determine 15-Lox activity after treatment by TSA. The results demonstrated that TSA induced cell growth inhibition via 15-Lox-1, in a dose- and time-dependent manner, and subsequently accompanied by the cell cycle arrest and induction of apoptosis. Moreover, growth inhibitory effect of TSA was associated with the elevation of 15-Lox-1 metabolite (13(S)-HODE). This study provided evidences that the inhibitory effect of TSA on the breast cancer cell growth occurs via the induction of 15-Lox-1 activity and 13(S)-HODE production. Our findings underline the possible role of 15-Lox-1/13(S)-HODE pathway as a promising molecular approach for the induction of apoptosis in breast cancer cells.

Microarray analysis of microRNA expression in cutaneous squamous cell carcinoma

BACKGROUND

MicroRNAs (miRNAs) are a novel class of short RNAs that are capable epigenetically regulating gene expression in eukaryotes. MicroRNAs have been shown to be dysregulated in a variety of cancers. The data on miRNA expression in cutaneous squamous cell carcinoma (cSCC) are very limited, and microarray-based miRNA expression profiles of cSCC have not yet been determined.

OBJECTIVE

To describe differentially expressed miRNAs in cSCC.

METHODS

Seven patients with cSCC were enrolled in the present study. Tumor biopsies (n=7) were taken from the center of each tumor. Adjacent healthy skin (n=7) was biopsied as a control (intraindividual control). miRNA expression profiles of all specimens were detected by microarray miRNA expression profiling based on miRBAse 16 scanning for 1205 potential human miRNA target sequences. The microarray results were confirmed by TaqMan quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Non-stringent filtering with a non-adjusted p ≤ 0.05 revealed thirteen up-regulated and eighteen down-regulated miRNAs. Non-stringent filtering with a non-adjusted p ≤ 0.01 revealed three up-regulated (hsa-miR-135b, hsa-miR-424 and hsa-miR-766) and six down-regulated (hsa-miR-30a*, hsa-miR-378, hsa-miR-145, hsa-miR-140-3p, hsa-miR-30a and hsa-miR-26a) miRNAs in cSCC.

CONCLUSION

This study reveals differentially expressed miRNAs that may play a role in the molecular pathogenesis of cSCC and that are excellent candidates for further validation and functional analysis.

15-Lipoxygenase-1 as a tumor suppressor gene in colon cancer: is the verdict in?

15-Lipoxygenase-1 (15-LOX-1) is an inducible and highly regulated enzyme in normal human cells that plays a key role in the production of lipid signaling mediators, such as 13-hydroxyoctadecadienoic acid (13-HODE) from linoleic acid. 15-LOX-1 significantly contributes to the resolution of inflammation and to the terminal differentiation of normal cells. 15-LOX-1 is downregulated in human colorectal polyps and cancers. Emerging data support a tumor suppressor role for 15-LOX-1, especially in colon cancer. These data indicate that 15-LOX-1 promotes various anti-tumorigenic events, including cell differentiation and apoptosis, and inhibits chronic inflammation, angiogenesis, and metastasis. The transcriptional repression of 15-LOX-1 in colon cancer cells is complex and involves multiple mechanisms (e.g., histone methylation, transcriptional repressor binding). Re-expression of 15-LOX-1 in colon cancer cells can function as an important therapeutic mechanism and could be further exploited to develop novel treatment approaches for this common cancer.

The Roles of Dietary PPARgamma Ligands for Metastasis in Colorectal Cancer

Dietary peroxisome proliferator-activated receptor (PPAR)gamma ligands, linoleic acid (LA) and conjugated linoleic acid (CLA), showed anticancer effects in colorectal carcinoma cells. LA is metabolized by two pathways. Cyclooxygenase (COX)-2 produces procarcinogenic prostaglandin E2, whereas 15-lipoxygenase (LOX)-1 produces PPARgamma ligands. The 15LOX-1 pathway, which is dominant in colorectal adenomas, was downregulated and inversely COX-2 was upregulated in colorectal cancer. LA and CLA inhibited peritoneal metastasis of colorectal cancer cells in nude mice. The inhibitory effect was abrogated by PPARgamma antisense treatment. A continuous LA treatment provided cancer cells quiescence. These quiescent cells formed dormant nests in nude mice administrated LA. The quiescent and dormant cells showed downregulated PPARgamma and upregulated nucleostemin. Thus, short-term exposure to dietary PPARgamma ligands inhibits cancer metastasis, whereas consistent exposure to LA provides quiescent/dormant status with possible induction of cancer stem and/or progenitor phenotype. The complicated roles of dietary PPARgamma ligands are needed to examine further.

Reversal of expression of 15-lipoxygenase-1 to cyclooxygenase-2 is associated with development of colonic cancer

AIMS

Two different pathways of linoleic acid (LA) metabolism have opposite effects on the development of colonic cancer: a protumoral prostaglandin cascade metabolized by cyclooxygenase (COX)-2, and an antitumoral peroxisome proliferator-activated receptor (PPAR)-gamma ligands metabolized by 15-lipooxygenase (LOX)-1. The aim was to examine the switching of the two LA metabolic pathways in colonic adenomas and carcinomas.

MATERIALS AND METHODS

The expression of 15LOX-1 mRNA and COX-2 protein was examined in 54 adenomas, 21 pTis carcinoma-in-adenoma lesions and 36 pT3/p Stage II carcinomas of the colon by in-situ hybridization and immunohistochemistry, respectively.

RESULTS

15LOX-1 expression was found in 89% (48 of 54) of adenomas, 43% (nine of 21) of adenomas and 10% (two of 21) of carcinomas in carcinoma-in-adenoma lesions, but not in pT3 carcinomas (P < 0.0001). In contrast, COX-2 production was found in 11% (six of 54) of adenomas, 52% (11 of 21) of adenomas and 71% (15 of 21) of carcinomas in carcinoma-in-adenoma lesions, and 92% (33 of 36) of pT3 carcinomas (P < 0.0001). Concurrence of 15LOX-1 down-regulation and COX-2 up-regulation was found in 6% (three of 54) of adenomas, 33% (seven of 21) of adenomas and 71% (15 of 21) of carcinomas in carcinoma-in-adenoma lesions, and 92% (33 of 36) of pT3 carcinomas (P < 0.0001).

CONCLUSIONS

These results suggest that switching of LA metabolism by reversal of the expression of 15LOX-1 and COX-2 is associated with acquisition of malignant potential in colonic neoplasia.

Recent advances in Oral Oncology

This paper reviews the main papers related to oral squamous cell carcinoma published in 2006 in oral oncology - an international interdisciplinary journal which publishes high quality original research, clinical trials and review articles, and all other scientific articles relating to the aetiopathogenesis, epidemiology, prevention, clinical features, diagnosis, treatment and management of patients with neoplasms in the head and neck, and orofacial disease in patients with malignant disease.