Chemoprevention of aerodigestive cancer

Identification of a novel oncogene, MMS22L, involved in lung and esophageal carcinogenesis

Genome-wide gene expression profile analyses using a cDNA microarray containing 27,648 genes or expressed sequence tags identified MMS22L (methyl methanesulfonate-sensitivity protein 22-like) to be overexpressed in the majority of clinical lung and esophageal cancers, but not expressed in normal organs except testis. Transfection of siRNAs against MMS22L into cancer cells suppressed its expression and inhibited cell growth, while exogenous expression of MMS22L enhanced the growth of mammalian cells. MMS22L protein was translocated to the nucleus and stabilized by binding to C-terminal portion of NFKBIL2 [nuclear factor of kappa (NFKB) light polypeptide gene enhancer in B-cells inhibitor-like 2]. Expression of a C-terminal portion of NFKBIL2 protein including the MMS22L-interacting site in cancer cells could reduce the levels of MMS22L in nucleus and suppressed cancer cell growth. Interestingly, reduction of MMS22L by siRNAs in cancer cells inhibited the TNF-α-dependent activation of RelA/p65 in the NFKB pathway and expression of its downstream anti-apoptotic molecules such as Bcl-XL and TRAF1. In addition, knockdown of MMS22L expression also enhanced the apoptosis of cancer cells that were exposed to DNA-damaging agents including 5-FU and CDDP. Our data strongly suggest that targeting MMS22L as well as its interaction with NFKBIL2 could be a promising strategy for novel cancer treatments, and also improve the efficacy of DNA damaging anticancer drugs.

Antiapoptotic efficacy of folic acid and vitamin B₁₂ against arsenic-induced toxicity

Earlier, we proposed that the ability of folic acid and vitamin B₁₂ to preserve systemic and mitochondrial function after short-term exposure to arsenic may prevent further progression to more permanent injury and pathological changes leading to cell death. To elucidate its mechanism, the present study examined the antiapoptotic efficacy of folic acid and vitamin B₁₂ against short-term arsenic exposure-induced hepatic mitochondria oxidative stress and dysfunction. Sixteen to eighteen weeks old male albino rats weighing 140-150 × g were divided into five groups: Control (A), Arsenic-treated (B), Arsenic + folic acid (C), Arsenic +vitamin B₁₂ (D), and Arsenic + folic acid + vitamin B₁₂ (E). Data generated indicated that folic acid and vitamin B₁₂ separately or in combination can give significant protection against alterations in oxidative stress and apoptotic marker parameters and downstream changes in mitochondria, namely pro-oxidative (NO, TBARS, OH⁻) and antioxidative defense (SOD, CAT, GSH) markers, iNOS protein expression, mitochondrial swelling, cytochrome c oxidase and Ca²⁺-ATPase activity, Ca²⁺ content, caspase-3 activity. Additionally, results of hepatic cell DNA fragmentation, arsenic load of blood, hepatic tissue and urine, and histological observations, all strongly support that both these supplements have efficacy in preventing apoptotic changes and cellular damage. As the mechanisms of actions of both of these supplements are methylation related, a combined application was more effective. Results further reveal new molecular targets through which folic acid and vitamin B₁₂ separately or in combination work to alleviate one critical component of arsenic-induced liver injury: mitochondria dysfunction.

Characterization of an Opa interacting protein 5 involved in lung and esophageal carcinogenesis

To identify potential molecular targets for diagnosis, treatment and/or prevention of lung and esophageal carcinomas, we screened for genes that were overexpressed in tumors through gene expression analyses of 120 lung cancers and 19 esophageal squamous-cell carcinomas using a cDNA microarray consisting of 27,648 cDNA or expressed sequence tags. In this process, we identified a gene, Opa interacting protein 5 (OIP5), to be highly transactivated in the majority of lung and esophageal cancers. Immunohistochemical staining using 336 archived non-small cell lung cancers and 305 esophageal squamous-cell carcinomas specimens demonstrated that OIP5 expression was significantly associated with poor prognosis of lung and esophageal cancer patients (P = 0.0053 and 0.0168, respectively), and multivariate analysis confirmed its independent prognostic value for non-small cell lung cancers (P = 0.0112). Suppression of OIP5 expression with siRNA effectively suppressed the growth of cancer cells, whereas the exogenous expression of OIP5 enhanced the growth of cancer cells. In addition, OIP5 protein is likely to be stabilized through its interaction with Raf1. OIP5 is a promising target for developing new prognostic biomarkers and anti-cancer drugs.

Activation of WD repeat and high-mobility group box DNA binding protein 1 in pulmonary and esophageal carcinogenesis

PURPOSE

We attempted to identify novel biomarkers and therapeutic targets for lung and esophageal cancers.

EXPERIMENTAL DESIGN

We screened for genes that were overexpressed in a large proportion of lung and esophageal carcinomas using a cDNA microarray representing 27,648 genes or expressed sequence tags. A gene encoding WDHD1, a WD repeat and high-mobility group box DNA binding protein 1, was selected as a candidate. Tumor tissue microarray containing 267 archival non-small cell lung cancers and 283 esophageal squamous cell carcinomas (ESCC) was used to investigate the clinicopathologic significance of WDHD1 expression. The role of WDHD1 in cancer cell growth and/or survival was examined by small interfering RNA experiments and cell growth assays. The mechanism of WDHD1 activation through its phosphorylation in cancer cells was examined by immunoprecipitation and kinase assays.

RESULTS

Positive WDHD1 immunostaining was associated with a poor prognosis for patients with non-small cell lung cancer (P = 0.0403) as well as ESCC (P = 0.0426). Multivariate analysis indicated it to be an independent prognostic factor for ESCC (P = 0.0104). Suppression of WDHD1 expression with small interfering RNAs effectively suppressed lung and esophageal cancer cell growth. In addition, induction of the exogenous expression of WDHD1 promoted the growth of mammalian cells. AKT1 kinase seemed to phosphorylate and stabilize the WDHD1 protein in cancer cells.

CONCLUSIONS

WDHD1 expression is likely to play an important role in lung and esophageal carcinogenesis as a cell cycle regulator and a downstream molecule in the phosphoinositide 3-kinase/AKT pathway, and that WDHD1 is a candidate biomarker and a promising therapeutic target for cancer.

Folic acid or combination of folic acid and vitamin B(12) prevents short-term arsenic trioxide-induced systemic and mitochondrial dysfunction and DNA damage

The effect of folic acid and folic acid + vitamin B(12) supplementation upon short-term arsenic-induced systemic and pancreatic islet cell mitochondria oxidative stress was investigated in male rats. Arsenic trioxide was administered orally at a dose of 3 mg kg body weight(-1) day(-1) for 30 days, and folic acid and vitamin B(12) were administered at a dose of 36 and 0.63 microg kg body weight(-1) day(-1), respectively, for 30 days. Compared to control, arsenic-treated group showed a significant increase in the levels of systemic oxidative markers, malondialdehyde (MDA), nitric oxide (NO), and hydroxyl radical (OH(-)) formation, which were found decreased significantly after supplementation either with folic acid or a combination of folic acid + vitamin B(12). Similar supplementations were found effective against arsenic-induced oxidative marker changes (MDA, NO, and OH(-)) in pancreatic islet cell mitochondria. Also, low activities of antioxidant defense enzymes such as superoxide dismutase and catalase, and level of antioxidant glutathione, all could regain significantly on supplementations both against systemic and islet cell mitochondria oxidative stress. Results of agarose-gel electrophoresis of DNA from lymphocytes and islet cells of arsenic-exposed rats showed DNA smearing, which could be reduced with simultaneous administration either with folic acid or a combination of folic acid + vitamin B(12). Significantly, similar supplementations were found effective in increasing the urinary clearance of arsenic. Together, these results indicate that folic acid and vitamin B(12) may be effective to reduce the arsenic-induced damage at molecular target level.

Cancer-testis antigen lymphocyte antigen 6 complex locus K is a serologic biomarker and a therapeutic target for lung and esophageal carcinomas

Gene expression profile analyses of non-small cell lung carcinomas (NSCLC) and esophageal squamous cell carcinomas (ESCC) revealed that lymphocyte antigen 6 complex locus K (LY6K) was specifically expressed in testis and transactivated in a majority of NSCLCs and ESCCs. Immunohistochemical staining using 406 NSCLC and 265 ESCC specimens confirmed that LY6K overexpression was associated with poor prognosis for patients with NSCLC (P = 0.0003), as well as ESCC (P = 0.0278), and multivariate analysis confirmed its independent prognostic value for NSCLC (P = 0.0035). We established an ELISA to measure serum LY6K and found that the proportion of the serum LY6K-positive cases was 38 of 112 (33.9%) NSCLC and 26 of 81 (32.1%) ESCC, whereas only 3 of 74 (4.1%) healthy volunteers were falsely diagnosed. In most cases, there was no correlation between serum LY6K and conventional tumor markers of carcinoembryonic antigen (CEA) and cytokeratin 19-fragment (CYFRA 21-1) values. A combined ELISA for both LY6K and CEA classified 64.7% of lung adenocarcinoma patients as positive, and the use of both LY6K and CYFRA 21-1 increased sensitivity in the detection of lung squamous cell carcinomas and ESCCs up to 70.4% and 52.5%, respectively, whereas the false positive rate was 6.8% to 9.5%. In addition, knocked down of LY6K expression with small interfering RNAs resulted in growth suppression of the lung and esophageal cancer cells. Our data imply that a cancer-testis antigen, LY6K, should be useful as a new type of tumor biomarker and probably as a target for the development of new molecular therapies for cancer treatment.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Free radical scavenging behavior of folic acid: evidence for possible antioxidant activity

The free radical scavenging properties and possible antioxidant activity of folic acid are reported. Pulse radiolysis technique is employed to study the one-electron oxidation of folic acid in homogeneous aqueous solution. The radicals used for this study are CCl(3)O(2)(*), N(3)(*), SO(4)(*-), Br(2)(*-), *OH, and O(*-). All these radicals react with folic acid under ambient condition at an almost diffusion-controlled rate producing two types of transients. The first transient absorption maximum is around 430 nm, which decays, and a simultaneous growth at around 390 nm is observed. Considering the chemical structure of folic acid, the absorption maximum at 430 nm has been assigned to a phenoxyl radical. The latter one is proposed to be a delocalized molecular radical. A permanent product has been observed in the oxidation of folic acid with CCl(3)O(2)(*) and N(3)(*) radicals, with a broad absorption band around 370-400 nm. The bimolecular rate constants for all the radical-induced oxidation reactions of folic acid have been measured. Folic acid is seen to scavenge these radicals very efficiently. In the reaction of thiyl radicals with folic acid, it has been observed that folic acid can not only scavenge thiyl radicals but can also repair these thiols at physiological pH. While carrying out the lipid peroxidation study, in spite of the fact that folic acid is considerably soluble in water, we observed a significant inhibition property in microsomal lipid peroxidation. A suitable mechanism for oxidation of folic acid and repair of thiyl radicals by folic acid has been proposed.