DIAGRAMA DE FLUJO

DISCUSSION & FUTURE RESEARCH

In this report we have compared the microRNA expression profiles from microarray and qPCR analysis on triple-negative breast cancer and normal breast tissue cell lines. MicroRNA expression profiles revealed a differential expression pattern in triple-negative breast cancer cells when compared to normal breast tissue cells. Amongst the cell lines, the microRNA expression profiles for the triple-negative breast cancer cells lines display values lower (down-regulated) or higher (up-regulated) than those of normal breast tissue cells. Previous research reports suggest that over or under expression of microRNAs have a significant impact on the expression of protein-coding genes. MicroRNAs have the ability to play a role in regulation of gene expression or in tumorgenesis, by acting as oncogenes or tumor suppressors (Buffa et al., 2011). Other reports have described altered expression of microRNAs in cancer tissues compared to normal tissues, suggesting that these microRNAs could potentially represent novel clinical and

prognostic markers (Carey et al., 2006). This research is novel because of its usage of cell lines that could serve as model systems to investigate deeper molecular level potential TNBC

biomarkers and drug therapeutic target. The findings may help to provide individualized

therapeutic options based on the microRNA expression profile of a TNBC patient. Additionally, it also reduces the percent error, since there are not multiple patient data sets involved. The usage of Partek Genomic Suite to find microRNA expression profiles, followed by validation of these results by real-time PCR will help to substantiate the claims that microRNAs can be used to determine treatment, prognostic, and diagnostic options for individuals with TNBC and other debilitating diseases.

We have shown here with the microRNA analysis of TNBC cells compared to normal breast cells that there are some indications of differences in the expressions of some microRNAs. These microRNAs have been shown to play an influential role in the pathways associated with many diseases, including, but not limited to breast cancer. For example, our study has shown that microRNA-21 is over-expressed in cancer cell lines. Previous studies have suggested that

microRNA-21 has a prognostic value in patients with cancer (Gazinska et al., 2013). Additionally, it has also been found that high expression of microRNA-21 mi According to Gazinska et al triple-negative breast cancer is associated with lesions that are characterized by a high incidence of TP53 mutations, as well as low levels of RB and high levels of p16 proteins might predict poor prognosis in patients with colorectal cancer (D'Ippolito & Iorio, 2013). Our study also demonstrated a decrease in expression in microRNA let-7a. These findings are consistent with a proposed repression of let-7 in cancer from Choudhury and Li (2012).

MicroRNA-34a was found to be down-regulated in breast cancer cell lines and tissues, compared with normal cell lines and the adjacent non-tumor tissues, respectively (Li et al., 2012). Our study also demonstrated a down-regulation of microRNA-34a. Martello et al, suggests in human breast cancer, high levels of microRNA-103/107 are associated with metastasis and poor

outcome (Martello et al., 2010). Data from our study reports an up-regulation of microRNA-103 amongst TNBC cells compared to normal breast tissue cells. Studies such as Avery et al and Chang et al, validate the finding of this study in relation to an up-regulation of microRNA-141 in cancer, however other studies such as Iorio et al and Eades et al, suggest the down-regulation of this microRNA in cancer.

These findings continue to support the role of microRNAs not just breast cancer, but other cancer types as well show roles of microRNAs as therapeutic, prognostic, and therapeutic

biomarkers. The findings from these this study also demonstrated the importance of microRNAs in cancer, specifically triple-negative breast cancer. The usage of complete cell lines will also create a platform for other research studied to be performed on. Additionally, a reduction in errors also prevalent due to the usage of individual cells lines, rather than studies with many participants.

Future directions include utilization of breast cell lines from Caucasian Women using the same methodology and comparison to African-American Women in order to derive a better understanding of the differences in expression levels of microRNAs normal and triple-negative breast cell lines between these groups of women. Additionally, determination of the roles of these miRNAs using different treatment methods will help to demonstrate the role and efficacy of these microRNAs.

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Appendix

Figure 4.4 Pathway Enrichment Analyses from Partek Genomic Suite

Figure 4.4 depicts the pathways associated with the microRNAs found on the microarray chip. This figure was created using Pathway Enrichment Analysis in Partek Genomic Suite. It identifies some of the pathways in which specific microRNAs have been known to interact with genes and proteins. MicroRNA-21 is listed on this diagram demonstrating its role in cell growth and survival.

Table 4.3 Display 32 differentially expressed microRNAs from Partek Genomic Suite

Table 4.3 displays the 32 differentially expressed microRNAs that were found using Partek Genomic Suite. All of these microRNAs have been shown in literature to play a role in cancer, however, only certain one have a role in Triple-Negative Breast Cancer.

Hsa-miR-103

Hsa-let-7a