Quantitative analysis of six gene products as candidate markers of early placental villi development in the human.

ABSTRACT

Early placental development is critical for successful pregnancy. Recently, we have reported that ~70 genes were differentially expressed in human placental villi between 6- and 8- weeks of gestation in cDNAbased expression arrays for ~400 PCR products, of which six specific gene products (COL4A4, CXCR4, ERBB2, HDAC1, HPRT1, and TNFRSF1A) appeared intriguing. In the present study we have examined expressions of these six candidate genes in placental villi obtained from 6-weeks, 7-weeks and 8-weeks (n = 6 for each group) human placental samples using quantitative real time RTPCR. We observed that there was considerable concordance (>95% confidence) in pair-wise analysis of transcript profiles between the two methods, however, absolute quantitative values as measured by quantitative RTPCR differed from those obtained from cDNA-based array analysis for 2 gene products (CXCR4 and ERBB2) out of 6 genes. No significant change was observed in the steady state expression of COL4A4 and HPRT1 during the time period examined. However, there was significant decrease in CXCR4 for 7-weeks (P< 0.01) and 8-weeks (P<0.05) samples, and significant (P<0.05) increase was seen for ERBB2 in 7-weeks and 8-weeks as compared to 6-weeks samples with no change between 7-weeks and 8-weeks samples. Moreover, significant (P< 0.05) increase for HDAC1 and decrease for TNFRSF1A was observed in 8-weeks samples as compared to 6-weeks samples with no change observed between 6-weeks and 7-weeks samples. We infer that it is essential that cDNA array-based data are verified in terms of quantitative estimates preferably by quantitative PCR before their use for any exploratory purpose. Taking together our previous array based data and the present study we conclude that a categorical balance exists between the expression of ERBB2 and HDAC1 genes affecting cell proliferation and differentiation in one hand, and CXCR4 and TNFRSF1A affecting chemotaxis, inflammatory response and apoptosis on the other hand. The expression of these genes appear important for the early development of human placental villi.