Affiliations: [a] Department of Basic Medical Sciences, King Saud Bin Abdulaziz University for Health Sciences (KSAU-HS), Kingdom of Saudi Arabia | [b] King Abdullah International Medical Research Center (KAIMRC), National Guard Health Affairs, Riyadh, Kingdom of Saudi Arabia
Correspondence:
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Corresponding author: Ahmad Aljada, Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center (KAIMRC), King Abdulaziz Medical City - Riyadh, National Guard Health Affairs, Mail Code: 3127, P.O. Box 3660, Riyadh 11481, Kingdom of Saudi Arabia. Tel.: +966 1 14295267; E-mail:aljadaa@ksau-hs.edu.sa
Abstract:
BACKGROUND: The mature human insulin receptor (INSR) has two
isoforms: The A isoform and the B isoform. INSR upregulation has been
suggested to play a role in cancer. OBJECTIVE: To establish quantitative PCR method for INSR transcript
variants and examine their differential expression as a diagnostic tumor
marker in breast cancer. METHODS: The differential expression of IR-A and IR-B were
evaluated by TaqMan qRT-PCR assay in the commercially available Breast
Cancer Disease cDNA and Cancer Survey cDNA arrays. RESULTS: The mRNA expression levels of IR-A was statistically
significantly higher in breast cancer when compared to normal breast tissue
while IR-B mRNA expression was down regulated significantly in breast
cancer. Stratification of patients into groups according to metastatic
stages indicated statistically significantly higher levels of IR-A mRNA in
clinical stage (CS)-IV, and lower IR-B levels in CS-IIA, CS-IIIB and
CS-IIIC. However, IR-A:IR-B ratio showed a statistically significant
increase in all stages. Cancer Survey cDNA array demonstrated lower levels
of IR-B mRNA in breast adenocarcinoma, liver carcinoma and lung carcinoma
only while IR-A expression was significantly altered in kidney carcinoma
without any significant differences in IR-A:IR-B ratios. CONCLUSIONS: The results demonstrate an increased IR-A:IR-B ratio
in all clinical stages of breast cancer. Thus, IR-A:IR-B ratio may have a
diagnostic biomarker utility in breast cancer.
