The human colon carcinoma cell line, HCT 116, can be grown in chemically defined media in the absence of exogenous growth factors. The addition of transferrin and insulin will significantly stimulate growth. The interaction of these growth factors with their receptors was studied to determine whether the synergistic action of insulin and transferrin on growth involved alterations in the growth-factor receptors. Redistribution of the transferrin receptor occurred in the presence of transferrin or transferrin plus insulin. The presence of insulin in the growth media resulted in occupation of cell-surface insulin receptors without a reduction in total insulin binding. Addition of transferrin with insulin resulted in a decrease in insulin binding to its receptor, with no alteration in receptor affinity. It appears that transferrin plays a role in regulating the insulin receptor and that this may contribute to the synergistic effect of insulin and transferrin on growth.

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DNA is the most accessible biologic material for obtaining information from the human genome because of its molecular stability and its presence in every nucleated cell. Currently, single nucleotide polymorphism genotyping and DNA methylation are the main DNA-based approaches to deriving genomic and epigenomic disease biomarkers. Upon the discontinuation of the Schleicher & Schuell IsoCode product (Dassel, Germany), which was a treated paper system to elute DNA from several biologic sources for polymerase chain reaction (PCR) analysis, a high-yielding DNA elution method was imperative. We describe here an improved procedure of the not fully validated Whatman pH-based elution protocol. Our DNA elution procedure from buccal cells collected in Whatman FTA cards (Whatman Inc., Florham Park, NJ) yielded approximately 4 microg of DNA from a 6-mm FTA card punch and was successfully applied for HLA-DQB1 genotyping. The genotypes showed complete concordance with data obtained from blood of the same subjects. The achieved high DNA yield from buccal cells suggests a potential cost-effective tool for genomic and epigenomic disease biomarkers development.

Host genetic background seems to play a key role in cervical carcinogenesis as only a small subset of women infected with high-risk human papillomaviruses (HPVs) develop cervical cancer. The rate of cervical cancer in Vietnamese women is notably high. To explore the association of human leukocyte antigen (HLA)-DQB1 alleles, HPV infection, and cervical dysplasia in this population, cervical smears were obtained from 101 women attending the obstetrics and gynecology clinic of Da Nang General Hospital in Vietnam. Besides the Papanicolaou test, HPV and HLA-DQB1 genotyping were performed using cervical smear DNA. Additionally, a subset of 30 blood samples was used as the gold standard for HLA genotyping. HLA-DQB1 alleles showed no association with HPV infection status. However, a positive association with cervical dysplasia was found for HLA-DQB1*0302 (P= 0.0229, relative risk (RR) = 4.737) and HLA-DQB1*0601 (P= 0.0370, RR = 4.038), whereas HLA-DQB1*0301 (P= 0.0152, RR = 0.221) was found negatively associated. The low diversity of HLA-DQB1 alleles, wide spectrum of HPV genotypes, and high prevalence of HPV 16 and HPV 18 observed in the study population suggest a permissive/susceptible genetic background that deserves further research. Total concordance of HLA-DQB1 genotyping results between blood and cervical cells confirms the potential value of cervical smears as an effective tool for the development of cervical cancer biomarkers.

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