Meta-Analysis Suggests Association of L-myc EcoRI Polymorphism with Cancer Prognosis

Association of polymorphisms and haplotype in the region of TRIT1, MYCL1 and MFSD2A with the risk and clinicopathological features of gastric cancer in a southeast Chinese population

To explore the association of polymorphisms in the region of three neighboring genes TRIT1, MYCL1 and MFSD2A with risk and clinicopathological features of gastric cancer, 19 tagging SNPs in this region were genotyped using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in a case-control study of 610 Chinese gastric cancer patients and 608 cancer-free controls. MFSD2A rs4233508 T>C CC genotype was associated with an increased risk of gastric cancer in younger patients and an increased risk of moderately/well-differentiated intestinal-type gastric cancer (adjusted odds ratio [OR], 1.74 and 1.50, respectively). TRIT1 rs11581557 T>G TG was associated with lymph node metastasis (TG versus TT/GG, adjusted OR, 1.64). MFSD2A rs12083239 GC genotype and TRIT1 rs2172362 or rs230310 homozygous genotype were associated with Lauren's classification (GC versus GG, adjusted OR, 1.69; GC versus GG/CC, adjusted OR, 1.74) and tumor site (rs2172362: CC versus CT, adjusted OR, 1.71; CC/TT versus CT, adjusted OR, 1.62; rs230310: CC versus CT, adjusted OR, 1.75; CC/TT versus CT, adjusted OR, 1.67) of gastric cancer, respectively. One TRIT1 haplotype, CCGT, was associated with lymph node metastasis and tumor site of gastric cancer (CCGT versus TTTT, adjusted OR, 1.91 and 1.55). This is believed to be the first report that several tagging SNPs and haplotypes in TRIT1, MYCL1 and MFSD2A region are significantly associated with risk and clinicopathological features of gastric cancer in a Chinese population. The findings might be useful for risk assessment and prognosis prediction of gastric cancer.

A 5'-region polymorphism modulates promoter activity of the tumor suppressor gene MFSD2A

BACKGROUND

The MFSD2A gene maps within a linkage disequilibrium block containing the MYCL1-EcoRI polymorphism associated with prognosis and survival in lung cancer patients. Survival discrepancies between Asians and Caucasians point to ethnic differences in allelic frequencies of the functional genetic variations.

RESULTS

Analysis of three single-nucleotide polymorphisms (SNPs) mapping in the MFSD2A 5'-regulatory region using a luciferase reporter system showed that SNP rs12072037, in linkage disequilibrium with the MYCL1-EcoRI polymorphism and polymorphic in Asians but not in Caucasians, modulated transcriptional activity of the MFSD2A promoter in cell lines expressing AHR and ARNT transcription factors, which potentially bind to the SNP site.

CONCLUSION

SNP rs12072037 modulates MFSD2A promoter activity and thus might affect MFSD2A levels in normal lung and in lung tumors, representing a candidate ethnically specific genetic factor underlying the association between the MYCL1 locus and lung cancer patients' survival.

MFSD2A is a novel lung tumor suppressor gene modulating cell cycle and matrix attachment

BACKGROUND

MFSD2A (major facilitator superfamily domain containing 2) gene maps on chromosome 1p34 within a linkage disequilibrium block containing genetic elements associated with progression of lung cancer.

RESULTS

Here we show that MFSD2A expression is strongly downregulated in non-small cell lung cancer cell lines of different histotypes and in primary lung adenocarcinomas. Experimental modulation of MFSD2A in lung cancer cells is associated with alteration of mRNA levels of genes involved in cell cycle control and interaction with the extracellular matrix. Exogenous expression of MFSD2A in lung cancer cells induced a G1 block, impaired adhesion and migration in vitro, and significantly reduced tumor colony number in vitro (4- to 27-fold, P < 0.0001) and tumor volume in vivo (approximately 3-fold, P < 0.0001). siRNA knockdown studies in normal human bronchial epithelial cells confirmed the role of MFSD2A in G1 regulation.

CONCLUSION

Together these data suggest that MFSD2A is a novel lung cancer tumor suppressor gene that regulates cell cycle progression and matrix attachment.

N6-isopentenyladenosine: A potential therapeutic agent for a variety of epithelial cancers

Isopentenyladenosine (i(6)A) is a product of isopentenyltransferases and, in mammals, occurs either bound to tRNA or as a free nucleoside. Sporadic reports have suggested an anticancer effect of i(6)A, mostly on leukemia cells. The present analysis of 9 human epithelial cancer cell lines derived from different types of malignant tissue revealed complete suppression of clonogenic activity in 8 of the lines after exposure to i(6)A at a concentration of 10 muM. Mechanistic studies showed that i(6)A tumor suppressor activity is associated with inhibition of cell proliferation, a block in DNA synthesis and morphological changes. These results point to i(6)A and to its possible derivatives as a new potential class of wide-spectrum anticancer agents.

Ethnic differences in frequencies of gene polymorphisms in the MYCL1 region and modulation of lung cancer patients' survival

Linkage disequilibrium (LD) analysis to refine a region associated with lung cancer progression on chromosome 1p34 identified a 106 kb LD block that includes MYCL1, TRIT1 (tRNA isopentenyltransferase 1) and MFSD2 (major facilitator superfamily domain-containing 2). Case-only association study on SNPs mapping in TRIT1 and MFSD2 indicated that the rare Leu allele (frequency: 0.04) of the TRIT1 Phe202Leu variation predicts short survival as compared to the common Phe/Phe genotype (hazard ratio (HR)=1.7; 95% CI, 1.03-2.86; P=0.039) in 335 Italian lung adenocarcinoma samples. A replication study in an independent population of 246 Norwegian lung cancer patients confirmed the significant association of the Phe202Leu polymorphism with patients' survival, but the rare allele was associated with better survival rate (HR=0.5; 95% CI, 0.26-0.91; P=0.023). The rare allele of TRIT1 Phe202Leu SNP was approximately seven-fold more frequent in Asian than in Caucasian subjects and three additional SNPs in the TRIT1 and MFSD2 genes showed ethnic differences in allelic frequencies. These results suggest that polymorphisms in the MYCL1 LD region affect lung cancer survival but that the functional element(s) may show population-specific patterns.

An intervention study of smoking cessation with feedback on genetic cancer susceptibility in Japan

BACKGROUND

To evaluate whether feedback of genetic information regarding an L-myc polymorphism, identified as impacting on tobacco-related cancer risk, has an influence on smoking cessation, an intervention study was conducted.

METHODS

We recruited smokers from first-visit outpatients at Aichi Cancer Center Hospital. Six hundred and seventeen participated and were allocated into two groups: the biomarker feedback group (BF) and the follow-up smoking status group (FS). The subjects were asked for their smoking status at enrolment and at 3- and 9-month follow-ups. BF subjects were notified about their L-myc genotype.

RESULTS

The smoking cessation rate at 9-month follow-up was essentially the same for both BF and FS cases, at 18.8% and 17.0%, respectively (P = 0.798). However, a difference in the rate was evident with non-cancer subjects (12.7% and 8.4%, respectively, P = 0.237), especially in females (15.0% and 4.2%, respectively, P = 0.024). The non-cancer subjects informed of their genotype were more likely to quit smoking than the FS patients; particularly in those having a risky genotype, this was significant (odds ratio: 2.87, P = 0.003). Again it was most prominent in females.

CONCLUSION

Feedback regarding an L-myc polymorphism did not impact on smoking cessation overall but appeared to benefit smokers without cancer. In addition, gender could affect the response to the feedback.