Maha Al-Rasheed

Curcumin induces apoptosis via inhibition of PI3'-kinase/AKT pathway in acute T cell leukemias.

Curcumin has been shown to possess variety of biological functions including anti-tumor activity. The mechanism by which curcumin inhibit cell proliferation remains poorly understood. In the present report, we investigated the effect of curcumin on the activation of apoptotic pathway in T-cell acute lymphoblastic leukemia (T-ALL) malignant cells. Our data demonstrate that curcumin causes dose dependent suppression of proliferation in several T cell lines. Curcumin treatment causes the de-phosphorylation/inactivation of constitutively active AKT, FOXO transcription factor and GSK3. Curcumin also induces release of cytochrome c accompanied by activation of caspase-3 and PARP cleavage. In addition, zVAD-fmk, a universal inhibitor of caspases, prevents caspase-3 activation and abrogates cell death induced by curcumin treatment. Finally, treatment of T-ALL cells with curcumin down-regulated the expression of inhibitor of apoptosis protein (IAPs). Taken together, our finding suggest that curcumin suppresses constitutively activated targets of PI3′-kinase (AKT, FOXO and GSK3) in T cells leading to the inhibition of proliferation and induction of caspase-dependent apoptosis.

Fatty Acid Synthase and AKT Pathway Signaling in a Subset of Papillary Thyroid Cancers

CONTEXT Fatty acid synthase (FASN) is an enzyme that plays a critical role in de novo synthesis of fatty acids. FASN is overexpressed in variety of human cancers, but its role has not been elucidated in papillary thyroid carcinoma (PTC). OBJECTIVE Our objective was to investigate the role of FASN and its relationship with phosphatidylinositol 3-kinase/AKT activation in a large series of PTC in a tissue microarray format followed by studies using PTC cell lines and Nude mice. DESIGN Analysis of apoptosis and cell cycle were evaluated by flow cytometry and DNA fragmentation assays. FASN and phospho-AKT protein expression was determined by immunohistochemistry and Western blotting. RESULTS Our data show that expression of FASN is associated with activated AKT (phospho-AKT) in a subset of PTC. Treatment of PTC cell lines (NPA-187, ONCO-DG-1, and B-CPAP) with C-75, an inhibitor of FASN, suppresses growth and induces apoptosis in all cell lines. Treatment of PTC cells with C-75 or expression of FASN small interfering RNA causes down-regulation of FASN and inactivation of AKT activity. Furthermore, treatment of PTC cell lines with C-75 results in apoptosis via the mitochondrial pathway involving the proapoptotic factor Bad, activation of Bax, activation of caspases, and down-regulation of antiapoptotic proteins. Finally, treatment of NPA-187 xenografts with C-75 results in growth inhibition of tumors in Nude mice via down-regulation of FASN expression and inactivation of AKT. CONCLUSIONS Our results suggest that FASN and activated AKT pathway may be a potential target for therapeutic intervention for the treatment of PTC.

Polymorphisms of selected Xenobiotic Genes contribute to the development of Papillary Thyroid Cancer susceptibility in Middle Eastern population

BackgroundThe xenobiotic enzyme system that enables us to detoxify carcinogens exhibits identifiable genetic polymorphisms that are highly race specific. We hypothesized that polymorphisms of these genes may be associated with risk of thyroid cancer. To evaluate the role of genetic polymorphisms of xenobiotic genes in thyroid cancer, we conducted a hospital-based case-control study in Saudi population.Methods223 incident papillary thyroid cancer cases and 513 controls recruited from Saudi Arabian population were analyzed for the association between polymorphisms in genes encoding folic acid metabolizing enzymes MTHFR and six xenobiotics-metabolizing enzymes including CYP1A1 T3801C, C4887A, GSTP1 A1578G, C2293T, GSTM1, GSTT1, NAT2 G590A, NQO*1 C609T, using PCR-RELP.ResultsAmong selected genes, CYP1A1 C4887A genotypes CA, AA and variant allele A demonstrated significant differences and greater risk of developing thyroid cancer comparing to wild type genotype CC (CA vs. CC; p < 0.0001, OR = 1.91, 95% CI = 1.36–2.70, AA vs. CC; p < 0.001, OR = 3.48, 95% CI = 1.74–6.96 and CA+AA vs. CC; p < 0.0001, OR = 2.07, 95% CI = 1.49–2.88). GSTT1 null showed 3.48 times higher risk of developing thyroid cancer (p < 0.0001, 95% CI = 2.48–4.88) while GSTM1 null showed protective effect (p < 0.05, OR = 0.72, 95% CI = 0.52–0.99). Remaining loci demonstrated no significance with risk.ConclusionOf the 9 polymorphisms screened, we identified GST, GSTM1 and CYP1A1 C4887A, may be of importance to disease process and may be associated with papillary thyroid cancer risk in Saudi Arabian population.

Polymorphisms of drug-metabolizing enzymes CYP1A1, GSTT and GSTP contribute to the development of diffuse large B-cell lymphoma risk in the Saudi Arabian population

The last four decades have seen significant increase in the incidence of non-Hodgkin lymphoma (NHL) as a possible result of increasing environmental carcinogens exposure. Based on the increasing evidence for the association between carcinogen-exposure-related cancer risk and xenobiotic gene polymorphisms, we have undertaken a hospital based case-control study on xenobiotic gene polymorphisms in Saudi individuals with a diagnosis of diffuse large B-cell lymphoma (DLBCL). Polymorphisms in five genes (CYP1A1, GSTT1, GSTP1, GSTM1, and NQO1) were characterized in 182 individuals with DLBCL and 513 normal controls using PCR-RFLP method. The CYP1A1*2C (p = 0.011, OR: 6.62, and 95% CI: 1.56 – 28.10), GSTT1 null (p ≤ 0.001, OR: 11.94, 95% CI: 7.88 – 18.12), and GSTP1 TT genotypes (p = 0.017, OR: 3.42, 95% CI 1.26 – 9.38) demonstrated significant association of DLBCL risk. None of the other alleles tested for proved to be significant indicators of DLBCL risk. Our findings suggest that polymorphisms of xenobiotic metabolizing enzyme genes may modify the individual susceptibility to develop DLBCL in Saudi Arabian population.

Genetic polymorphisms of methylenetetrahydrofolate reductase and promoter methylation of MGMT and FHIT genes in diffuse large B cell lymphoma risk in Middle East

Diffuse large B cell lymphoma (DLBCL) is one of the most common non-Hodgkin’s lymphoma types. Methylenetetrahydrofolate reductase (MTHFR) balances the pool of folate coenzymes in one carbon metabolism of deoxyribonucleic acid (DNA) synthesis and methylation; both are implicated in carcinogenesis of many types of cancer including lymphoma. Two common variants in the MTHFR gene (C677T and A1298C) have been associated with reduced enzyme activity, thereby making MTHFR polymorphisms a potential candidate as a cancer-predisposing factor. The O6 methylguanine DNA methyltransferase (MGMT) and fragile histidine triad (FHIT) genes are transcriptionally silenced by promoter hypermethylation in DLBCL. These genetic differences are highly race specific and have never been screened in the Saudi DLBCL patients. We conducted a hospital-based case–control study including 160 DLBCL cases and 511 Saudi control samples analyzing the MTHFR C677T and A1298C functional polymorphisms by the restriction fragment length polymorphism method and their association with MGMT and FHIT genes promoter hypermethylation. Our data demonstrated that Saudi individuals carrying MTHFR genotype 1298CC (p < 0.001) and the 1298C allele (p = 0.012) had 4.23 and 1.73-fold higher risk of developing DLBCL, respectively. Additionally, combined genotype CCCC (MTHFR 677CC + MTHFR 1298CC) was associated with 3.489-fold, and CTCC (MTHFR 677 CT + 1298CC) was related to 9.515-fold higher risk, compared with full MTHFR enzyme activity. No significant association between MTHFR variant genotypes and methylation of MGMT and FHIT genes were observed. Our findings suggested that polymorphisms of MTHFR enzyme genes might be associated with the individual susceptibility to develop DLBCL. Additionally, the results indicated that MTHFR variants were not related to MGMT or FHIT hypermethylation in DLBCL.

A very low incidence of BRAF mutations in Middle Eastern colorectal carcinoma.

BackgroundRecent studies emphasize the role of BRAF as a genetic marker for prediction, prognosis and risk stratification in colorectal cancer. Earlier studies have reported the incidence of BRAF mutations in the range of 5-20% in colorectal carcinomas (CRC) and are predominantly seen in the serrated adenoma-carcinoma pathway characterized by microsatellite instability (MSI-H) and hypermethylation of the MLH1 gene in the setting of the CpG island methylator phenotype (CIMP). Due to the lack of data on the true incidence of BRAF mutations in Saudi Arabia, we sought to analyze the incidence of BRAF mutations in this ethnic group.Methods770 CRC cases were analyzed for BRAF and KRAS mutations by direct DNA sequencing.ResultsBRAF gene mutations were seen in 2.5% (19/757) CRC analyzed and BRAF V600E somatic mutation constituted 90% (17/19) of all BRAF mutations. BRAF mutations were significantly associated with right sided tumors (p = 0.0019), MSI-H status (p = 0.0144), CIMP (p = 0.0017) and a high proliferative index of Ki67 expression (p = 0.0162). Incidence of KRAS mutations was 28.6% (216/755) and a mutual exclusivity was noted with BRAF mutations (p = 0.0518; a trend was seen).ConclusionOur results highlight the low incidence of BRAF mutations and CIMP in CRC from Saudi Arabia. This could be attributed to ethnic differences and warrant further investigation to elucidate the effect of other environmental and genetic factors. These findings indirectly suggest the possibility of a higher incidence of familial hereditary colorectal cancers especially Hereditary non polyposis colorectal cancer (HNPCC) syndrome /Lynch Syndrome (LS) in Saudi Arabia.

Differences in the Expression of Apoptotic Proteins in Burkitt's Lymphoma Cell Lines: Potential Models for Screening Apoptosis-Inducing Agents

Mammalian cells undergo programmed cell death by orchestrated interactions involving multiple independent pathways. At least one of them, the p53- dependent pathway is commonly compromised in Burkitts lymphoma (BL) cell lines. Differences in the integrity of this pathway in various BL cell lines have made them useful experimental models in understanding response to standard or novel anti-tumor drugs vis-a-vis the p53 pathway. Non-p53-dependent loss of apoptotic regulation also contributes to the genesis and/or progression of lymphomas and it is possible that BL cell lines also represent these models. We have characterized the expression of multiple apoptotic proteins in a panel of BL cell lines and describe cell lines with loss of cIAP1, cIAP2, Bax, Bak, Bcl-Xs and p38 MAP-kinase. This data should make this panel of cell lines a useful screening system for testing novel apoptotic inducers.

colorectal cancer risk is not associated with increased levels of homozygosity in saudi Arabia

Purpose:Runs of homozygosity (ROHs) represent a measure of the extent of autozygosity and are correlated with the extent of inbreeding. Recently, it has been suggested that ROHs may contribute to the risk of colorectal cancer (CRC). The high rate of consanguinity and CRC in the Saudi population prompted us to test the role of autozygosity in the CRC risk.Methods:We compared 48 Saudi CRC patients to 100 ethnically matched controls, processed on the Affymetrix 250K StyI SNP GeneChip platform and analyzed using the plink package.Results:We could find no evidence of a significant relationship between autozygosity and CRC risk.Conclusion:The negative results in our study add additional significance to what has been previously reported in literature, as this is the first study to address these questions in an inbred population. Our subgroup analysis of patients with microsatellite unstable–positive tumors as compared with other groups did not significantly change our results. Although these results do not rule out the presence of recessively acting CRC-predisposing genes in a small percentage of patients, which our relatively small sample size could not capture, they suggest that such genes are unlikely to account for the disturbingly high incidence of CRC in our consanguineous population.Genet Med 2012:14(8):720–728

Frequent silencing of fragile histidine triad gene (FHIT) in Burkitt's lymphoma is associated with aberrant hypermethylation.

The fragile histidine triad (FHIT) gene, a potential tumor‐suppressor gene, is frequently inactivated in multiple human cancers. However, the FHIT gene remains largely unexplored in Burkitts lymphoma (BL). Hence, we assessed whether loss of FHIT expression occurs in BL, and, if so, what is the mechanism of such loss. Lack of protein expression was observed in 50% of BL cell lines. Methylation‐specific polymerase chain reaction (MSP) showed that 45% of BL cell lines carried aberrantly methylated FHIT alleles. Sequencing of bisulfite‐treated DNA confirmed these data and indicated a very high density of methylation in all methylated alleles. Real‐time, quantitative reverse‐transcription PCR analysis indicated that attenuation of full‐length FHIT transcription was correlated with methylation. Sequencing of transcripts illustrated that aberrant transcription resulting in loss of FHIT exons occurred more commonly in BL containing unmethylated FHIT genes. However, such transcripts often coexisted with full‐length FHIT transcripts. Not surprisingly, therefore, loss of FHIT protein in BL correlated with CpG island methylation, rather than with aberrant transcription. FHIT methylation also was detected in 31% (16 of 51) of the primary BLs examined, including 2 samples whose derived cell lines also manifested FHIT hypermethylation. Aberrant methylation can thus occur in vivo. In summary, this report provides evidence that epigenetic modification frequently results in loss of FHIT expression in BL.

Diagnostic value of recombinant human thyrotropin-stimulated ¹²³I whole-body scintigraphy in the follow-up of patients with differentiated thyroid cancer.

Purpose: Published data on recombinant human thyrotropin- (rhTSH-) stimulated iodine-123 (123I) diagnostic whole-body scintigraphy (DxWBS) in differentiated thyroid cancer (DTC) surveillance after initial treatment are limited. We sought to evaluate this modalitys diagnostic value in this setting. Materials and Methods: We retrospectively compared rhTSH-stimulated 123I DxWBS results with DTC status concurrently determined by stimulated serum thyroglobulin (Tg) measurement, neck ultrasonography, and other imaging studies. Disease was considered present based on stimulated Tg level ≥1 &mgr;g/L without interfering Tg autoantibodies with or without positive imaging or biopsy-proven DTC. We also compared scan positivity and disease detection rates of rhTSH-stimulated DxWBS scans obtained with 123I with those acquired with iodine-131 (131I) during the same period. The sample comprised 105 consecutive totally thyroidectomized patients undergoing rhTSH-aided DxWBS with I-123 (n = 67) or with 131I (n = 38) for diagnostic follow-up. rhTSH, 0.9 mg/d, was injected intramuscularly on 2 consecutive days. Oral diagnostic activities of 5 to 10 mCi (185–370 MBq) 123I or 3 mCi (111 MBq) 131I were given on the third day. DxWBS was performed 24 hours (123I) or 48 to 72 hours (131I) later. Results: rhTSH-aided 123I DxWBS scans showed 35.3% sensitivity, 98.0% specificity, 85.7% positive predictive value, and 81.6% negative predictive value. rhTSH-stimulated 123I and 131I DxWBS did not differ in scan positivity (10.4% vs. 13.2%, P = 0.75) or disease detection rates (35.3% vs. 27.8%, P = 1.00). Conclusions: In DTC, rhTSH-aided 123I DxWBS achieves comparable results in diagnostic follow-up with those of rhTSH-aided 131I DxWBS. Future studies should address the preablation setting and scan activity and timing.