An Integrative Approach Uncovers Biomarkers that Associate with Clinically Relevant Disease Outcomes in Vulvar Carcinoma

Vulvar squamous cell carcinoma (VSCC) is a rare disease that has a high mortality rate (∼40%). However, little is known about its molecular signature. Therefore, an integrated genomics approach, based on comparative genome hybridization (aCGH) and genome-wide expression (GWE) array, was performed to identify driver genes in VSCC. To achieve that, DNA and RNA were extracted from frozen VSCC clinical specimens and examined by aCGH and GWE array, respectively. On the basis of the integration of data using the CONEXIC algorithm, PLXDC2 and GNB3 were validated by RT-qPCR. The expression of these genes was then analyzed by IHC in a large set of formalin-fixed paraffin-embedded specimens. These analyses identified 47 putative drivers, 46 of which were characterized by copy number gains that were concomitant with overexpression and one with a copy number loss and downregulation. Two of these genes, PLXDC2 and GNB3, were selected for further validation: PLXDC2 was downregulated and GNB3 was overexpressed compared with non-neoplastic tissue. By IHC, both proteins were ubiquitously expressed throughout vulvar tissue. High expression of GNB3 and low PLXDC2 immunostaining in the same sample was significantly associated with less lymph node metastasis and greater disease-free survival. On the basis of a robust methodology never used before for VSCC evaluation, two novel prognostic markers in vulvar cancer are identified: one with favorable prognosis (GNB3) and the other with unfavorable prognosis (PLXDC2).

IMPLICATIONS

This genomics study reveals markers that associate with prognosis and may provide guidance for better treatment in vulvar cancer. Mol Cancer Res; 14(8); 720-9. ©2016 AACR.

Abstract 516: S100P: Cause or effect of vulvar carcinoma prognostic status

Introduction: Vulvar squamous cell carcinoma (VSCC) is a rare disease accounting for 3 to 5% of female genital-tract malignancy. Conventional surgical treatment of VSCC can be very aggressive and mutilating, resulting in relevant psychosexual implications for patients. S100 family comprises genes involved in several molecular pathways including proliferation, differentiation and migration. Among them, S100P has a significant role during the development and progression of different cancers being able to promote migration. Aims: To evaluate the role of S100P in VSCC and associate it with clinical outcomes. Methods: 5 samples of frozen VSCC tissue were microdissected after carefully revision of the HE slides. Two areas of the same tumor - invasion front (IF) and center of the tumor (CT)- were selected for different dissections. Each of the samples had their total RNA extracted, amplified and analyzed using Whole Human Genome 8×60K array (Agilent Technologies). Results of RNA expression were compared between both groups (IF and CT) from the same tumor. The differential expressed genes were selected by RankProduct methodology, which pointed out S100P as one of the main ones. Then, 66 VSCC formalin-fixed paraffin-embbebed samples were used for immunohistochemical (IHC) analysis of S100P. The stained slides were digitalized and evaluated using Pannoramic250 Flash II and Pannoramic Viewer, respectively (3DHistechTM). HScore was calculated based on the percentage and the intensity of stained cells. The statistical analysis was performed on SPSS® Statistics software, version 21.0.0.0, with a confidence interval of 95%. Results: The gene wide expression analysis presented a ranked list with 69 genes, one of them, S100P. The IHC results showed that IF had significant (p = 0,002) higher HScore values (mean = 132,79) compared to CT (mean = 112,34). Analysis of IF staining hot spots showed that higher expression of S100P is related with worse prognosis (p = 0,041). In addition, the greater is the difference in S100P expression between IF compared to CT of the same tumor, the worse is the patient prognosis in cancer specific survival analysis (p = 0,035). Conclusion: S100P is a marker of worse prognosis in VSCC. Also, its heterogeneity of expression between IF and CT seems to be related to a more aggressive component of the disease, maybe due to its relation with cell motility and migration. A comprehensive IHC assessment of S100P can bring important contribution for stablishing prognosis of women with vulvar cancer.

Note: This abstract was not presented at the meeting.

Citation Format: Mayara C. Botelho, Andre M. Lavorato-Rocha, Iara S. Rodrigues, Beatriz M. Maia, Katia C. Carvalho, Renato Puga, Fernando A. Soares, Rafael M. Rocha. S100P: Cause or effect of vulvar carcinoma prognostic status. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 516. doi:10.1158/1538-7445.AM2015-516