Restriction fragment length polymorphism of the L-myc oncogene in non-Hodgkin's lymphoma patients from India

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

The L-myc EcoRI polymorphism is a noncoding variation in the second intron of the L-myc gene, resulting in S and L alleles. Individuals carrying the S allele tend to have poor prognosis and increased risk of several tumor types, although controversial results have been reported. A meta-analysis of 36 studies on L-myc EcoRI genotyping, including 3563 patients with different types of cancer and 2953 controls, was performed. In lung cancer patients the S/S genotype was significantly associated with lymph node metastasis [odds ratio (OR), 2.8; 95% confidence interval (CI), 1.8-4.3], distant metastasis (OR, 4.7; 95% CI, 2.4-9.2), and stage (OR, 2.3; 95% CI, 1.2-4.4). No association was observed between the S/S genotype and cancer (OR, 1.1; 95% CI, 0.8-1.4). In patients with other cancers, the S/S genotype was significantly associated with tumor recurrence (OR, 2.8; 95% CI, 1.4-6.0), whereas no significant association was seen for the other prognostic parameters. When all types of cancer were examined together, the S/S genotype was associated with lymph node metastasis (OR, 2.3; 95% CI, 1.6-3.3), distant metastasis (OR, 2.9; 95% CI, 1.8-4.6), clinical stage (OR, 1.8; 95% CI, 1.2-2.9), and cancer risk (OR, 1.25; 95% CI, 1.07-1.45). The meta-analysis suggests that the L-myc EcoRI polymorphism is a marker of tumor prognosis in lung cancer and possibly in other types of cancer.

HPV16/18 prevalence in cervical lesions/cancers and p53 genotypes in cervical cancer patients from India

OBJECTIVES

The HPV16/18 code for an oncoprotein-E6, which binds to p53 tumor suppressor protein and degrades the protein via ubiquitination. A common polymorphism of p53 in exon 4 codon 72, resulting in either proline (Pro) or arginine (Arg), affects HPV16/18 E6-mediated degradation of p53 protein in vivo. Hence, in the current study we investigated the prevalence of HPV16/18 in cervical lesions and the distribution of p53 genotypes in cervical cancers and normal healthy women.

METHODS

DNA from 337 Indian women with invasive cervical cancers, 164 women with clinically normal cervix, 64 women with low-grade squamous intraepithelial lesions (LSIL), and 5 women with high-grade squamous intraepithelial lesions (HSIL) was examined for the presence of HPV16/18 using consensus primers in a polymerase chain reaction (PCR), and the specific HPV type was identified by Southern hybridization of the PCR product using HPV16/18 type-specific nucleotide sequences as probes. Further, 134 women with cervical cancers and 131 healthy women were used to determine the frequency of p53 genotypes, Pro/Pro, Arg/Arg, and Pro/Arg, using peripheral blood cell DNA to indicate the constitutional genotypes and allele-specific primers, in a PCR-based assay.

RESULTS

We observed a prevalence of HPV16/18 in 77% (258/337) of cervical cancer patients, 38% (24/64) of LSILs, 4 of 5 HSILs, and 15.2% (25/164) of normal healthy women. The frequency of distribution of the three genotypes of p53 codon 72 in a subgroup of the HPV16/18-positive cervical cancer patients was Pro/Pro 0.18 and Arg/Arg 0.26, with the heterozygous Pro/Arg 0.56, differing significantly from the genotype frequency in the normal healthy women (chi(2) = 6.928, df = 2, P < 0.05).

CONCLUSIONS

A high prevalence of HPV16/18 was observed in the cervical cancers. The prevalence in LSILs confirms HPV16/18 infection as an early event and further indicates a role in progression of lesions. The p53 genotype distribution indicated that women homozygous for Arg genotype were at a 2.4-fold higher risk for developing HPV16/18-associated cervical carcinomas, compared to those showing heterozygous Pro/Arg genotype (odds ratio 2.4, 95% confidence interval 1.89 to 3.04).

Is there any correlation between restriction fragment length polymorphism of the L-MYC gene and metastasis of human nonsmall cell lung cancer?

A potential molecular marker associated with cancer susceptibility as well as metastasis, prognosis and adverse survival, is the L-myc gene. The studies of lung cancer patients from different populations have yielded controversial results. We studied 64 nonsmall cell lung cancer (NSCLC) patients and 37 healthy controls of Turkish origin for L-myc gene polymorphism. Our aim was to test the hypothesis that there was association between L-myc S allele in NSCLC and predisposition to the disease and TNM stage indicating tumor size, node classification and metastasis. Polymerase chain reaction restriction fragment length polymorphism and agarose gel electrophoresis were used to determine the L-myc oncogene genotypes. We found no significant difference, both in the distribution of the LL, LS and SS genotypes and in the allelic frequencies, between the patient group and the control group; that is, the frequencies of L-myc alleles were, L and S, 0.59 and 0.41, 0.60 and 0.40, respectively. Our data between the patient group and the control group; that is, the frequencies of L-myc alleles were, L and S, 0.59 and 0.41, 0.60 and 0.40, respectively. Our data concerning age, sex, size of tumors, histological type of tumors showed no significant association with L-myc genotype. However, a higher frequency of L-myc S allele in the squamous cell carcinoma compared to other histological groups was found, although this difference was not statistically significant. No association was found between the L-myc RFLP and increased risk of metastasis either to the lymph nodes or to other organs. Our results suggested that L-myc gene polymorphism was not a suitable prognostic marker of metastatic development in Turkish NSCLC patients.