Major Project

Increased expression of RRM2 by human papillomavirus E7 oncoprotein promotes angiogenesis in cervical cancer

Wang et al. (2014) conducted a study to investigate roles of ribonucleotide reductase M2 (RRM2) as a novel potential target activated by human papillomavirus (HPV) E7 oncoprotein on cervical cancer progression. In previous studies (Rosty et al., 2005; Kuner et al., 2007) found many novel potential downstream genes for HPVE7 oncoprotein by microarray technique, RRM2 is the one of novel potential downstream genes for HPVE7 oncoprotein. In addition, overexpression RRM2 is also associated with tumor angiogenesis and tumor metastasis (Zhang et al., 2009; Zhou et al., 1998.) The study was divided into three parts; cell culture, animal, and human specimen experiments. In cell culture, HeLa cell line, a positive HPV type 18 cervical cell line which has HPVE7 oncoprotein, and C33A cell line, a negative HPV which has no HPV oncoprotein, were used in the study. C33A cell line was transfected with plasmid for HPVE7 for biochemical characterization as HeLa cell line to confirm results of roles of RRM2 on cervical cancer progression. In animal experiment, BALB/c nude mice were inoculated subcutaneously with 5x10⁶ C33A-transfected RRM2 (C33A-RRM2) and C33A-transfected empty vector (C33A-V). In human specimen experiment, human cervical cancer samples were collected from cervical cancer patients to stain immunohistochemistry for RRM2 and CD31, an angiogenesis biomarker, expressions. The results showed RRM2 as a novel target for HPVE7 to mediated cervical cancer progression in all parts of experiment.  Therefore, RRM2 may be a therapeutic target for cervical cancer treatment or a biomarker for predicting the prognosis of cervical cancer in the future.

       This provides a novel target downstream activated of HPVE7 to mediate cervical cancer progression. However, there are some limitations.

1.  This study chose only positive HPV type 18 cancer cell line (HeLa cells). The research may choose other positive HPV type 16 cancer cell lines such as CaSki cells to confirm their results.

2.  For animal experiment, the study used nude mice-transplanted C33A-RRM2 only to determine the roles of RRM2 in cervical cancer progression. The study may use the posivtive HPVE7 cell line together to confirm the in vivo results.

3.   For human specimen, the study should determine correlation between RRM2 expression and cervical cancer stage for more information for predicting the prognosis of cervical cancer in the future.

The strength of the study is that the confirmation of supporting roles of RRM2 in cervical cancer progression in positive HPVE7 HeLa cell line by comparing to negative HPVE7 C33A cell line which were transfected with RRM2.

References:

     1. Wang, N., Zhan, T., Ke, T., Huang, X., Ke, D., Wang, Q., & H, Li. (2014). Increased expression of RRM2 by human papillomavirus E7 oncoprotein promotes angiogenesis in cervical cancer. Br J Cancer. 18; 110(4):1034-44.

     2. Rosty, C., Sheffer, M., Tsafrir, D., Stransky, N., Tsafrir, I., Peter, M., & et al. (2005). Identification of a proliferation gene cluster associated with HPV E6/E7 expression level and viral DNA load in invasive cervical carcinoma. Oncogene. 27; 24(47):7094-104.

   3. Kuner, R., Vogt, M., Sultmann, H., Buness, A., Dymalla, S., Bulkescher, J., & et al. (2007). Identification of cellular targets for the human papillomavirus E6 and E7 oncogenes by RNA interference and transcriptome analyses. J Mol Med (Berl). 85(11):1253-62. Epub 2007 Jun 23.

    4. Zhang, K., Hu, S., Wu, J., Chen, L., Lu, J., Wang, X., et al. (2009). Overexpression of RRM2 decreases thrombspondin-1 and increases VEGF production in human cancer cells in vitro and in vivo: implication of RRM2 in angiogenesis. Mol Cancer. 28;8:11.

     5. Zhou, B.,S., Tsai, P., Ker, R., Tsai, .J, Ho, R’, Yu, J., et al. (1998). Overexpression of transfected human ribonucleotide reductase M2 subunit in human cancer cells enhances their invasive potential. Clin Exp Metastasis. 16(1):43-9.