Question

cancer biology

15. The carly pioneers of oncogene research were using a 3T3 cell transformation assay, an immortalized mouse cell line that "stacks the deck" in favor of transformation- and enables it via transfection with a single oncogene. Which of the following is NOT TRUE regarding 3T3 cells? 1. They were immortalized spontaneously. b. They evolve within the first 25 cell-transfers from a diploid to a tetrapl C. They are 100% disome (normal karyotype). d. They show chromosomal imbalances typical of human solid cancers of ect mal origin, 16. Despite the fact that their genotypes are the same, the phenotypes of identical twins appear to drift apart over the years. What is the primary mechanism that is responsible for this observation? a. The generation of chemical carcinogenic DNA damage is random. b. Differences in diet and other environmental factors influence epigenetic controls. c. Defects in DNA damage responses are often different in fraternal twins d. Exposure to UV irradiation can directly impact tumor metabolism. 17. What single molecule is responsible for the highest cancer incidence and greatest cancer mortality in the US? a. Aflatoxin B b. Aflatoxin A c. Dioxane d. Estradiol 18. The "triple negative" genotype in breast cancer refers to: a. Tumor cells lacking telomerase, ras and Large T antigen. b. Tumor cells lacking p53, Rb and MDM2. | C. Tumor cells lacking hexose kinase, cyclin D and RAPI. d. Tumor cells lacking ER, PR and erbB2.

Answer 1

15. 3T3 cell lines are not normal cell line but are continuous cell line for solid tumor. They were prepared after 3 days of transfer. So yes we can say they were immortalized immediately. It has been reported that NIH 3T3 cell lines were evolved within the firat 25 days of transfer from diploid to a tetraploid cell line.

So, option C is the only incorrect because they are not normal karyotype but are immortalized cancer cell lines.

16. The phenotypes of identical twins drifts apart over years becauss of the environmental factors which regulates the expression pattern without changing the gene. So, option B is correct.

17. Aflatoxin B is leading cause of cancer in the US.

18. Triple negative breast is defined by the absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2) expression. Her2 is also known as erbB2. So, option D is correct.

Aberant signalling thriugh ras has been studied in TNBC.

Overexpression of MDM2 strongly promotes cell proliferation and tumor cell circulation in TNBC. It help in potential metastasis.

TNBC has shown over expression of cyclin D1.