Kotulak Anna, Wronska Agata, Kobiela Jaroslaw, Godlewski Janusz, Stanislawowski Marcin, Wierzbicki Piotr
Department of Histology, Medical University of Gdansk, Gdansk.
Folia Histochem Cytobiol. 2016;54(3):166-170. doi: 10.5603/FHC.a2016.0018. Epub 2016 Sep 21.
The colorectal cancer (CRC) is one of the most frequent cancer in Poland and worldwide. This disease is characterized by distinct genetic alterations. p73 belongs to the p53 gene family; however, its role in the pathogenesis of CRC has not been completely understood. p73 gene encodes several mRNA variants and protein isoforms with its longest and fully functional p73a (mRNA) and TAp73a (protein) isoform. The aim of the study was to investigate p73 gene expression at the mRNA (p73a) and protein (TAp73a) levels in CRC.
Small sections of the crc tumor tissue and macroscopically unchanged colon mucosa and submucosa from the dissection margin were collected from 23 patients diagnosed with CRC. p73 mRNA levels were measured by Real-time PCR (QPCR) method and the expression level of TAp73a protein was assessed by Western blotting (WB) and immunohistochemical (IHC) staining.
We found a 37% decrease in the level of p73a mRNA in neoplastically changed (tumor) compared with unchanged normal colon tissue from the surgical margin (p = 0.041). No correlations were found between mRNA levels in cancer tissue and clinical-pathological parameters. The semi-quantification of TAp73a protein revealed lower and higher TAp73a protein contents in 11/23 and 12/23 of tumor samples, respectively, when compared with the median value of TAp73a protein in normal colon tissue (p = 0.61). The level of TAp73a protein level was 5 times lower in poorly differentiated cancer cells (G3) in comparison to moderately differentiated ones (G2; p = 0.02). No statistically significant correlations were observed between the level of the TAp73a protein and clinical-pathological patients' characteristics. The IHC analysis of TAp73a protein presence in CRC samples showed decreased immunoreactivity when compared with matched sections of the unchanged colon wall in 4/9 patients, similar intensity of the IHC reaction in 4/9 patients and increased immunoreactivity in 1/9 patients. The TAp73a protein was localized mainly in the cytoplasm of the cancer cells. No statistically significant correlations between IHC results and clinical-pathological features of the patients were found.
The obtained results suggest that the p73 gene may play a role as a tumor suppressor in the CRC progression.
结直肠癌（CRC）是波兰和全球最常见的癌症之一。这种疾病具有明显的基因改变。p73属于p53基因家族；然而，其在结直肠癌发病机制中的作用尚未完全明确。p73基因编码多种mRNA变体和蛋白质异构体，其中最长且功能完整的是p73a（mRNA）和TAp73a（蛋白质）异构体。本研究的目的是调查结直肠癌中p73基因在mRNA（p73a）和蛋白质（TAp73a）水平的表达情况。
从23例确诊为结直肠癌的患者中收集结直肠癌肿瘤组织的小块样本以及手术切缘肉眼未见改变的结肠黏膜和黏膜下层。通过实时定量聚合酶链反应（QPCR）方法测量p73 mRNA水平，并通过蛋白质免疫印迹法（WB）和免疫组织化学（IHC）染色评估TAp73a蛋白的表达水平。
我们发现与手术切缘未改变的正常结肠组织相比，肿瘤性改变（肿瘤）组织中p73a mRNA水平降低了37%（p = 0.041）。在癌组织的mRNA水平与临床病理参数之间未发现相关性。TAp73a蛋白的半定量分析显示，与正常结肠组织中TAp73a蛋白的中位数相比，分别有11/23和12/23的肿瘤样本中TAp73a蛋白含量较低和较高（p = 0.61）。与中度分化的癌细胞（G2）相比，低分化癌细胞（G3）中TAp73a蛋白水平低5倍（p = 0.02）。在TAp73a蛋白水平与患者临床病理特征之间未观察到统计学上的显著相关性。对结直肠癌样本中TAp73a蛋白存在情况的免疫组织化学分析显示，与未改变的结肠壁匹配切片相比，4/9的患者免疫反应性降低，4/9的患者免疫组织化学反应强度相似，1/9的患者免疫反应性增加。TAp73a蛋白主要定位于癌细胞的细胞质中。在免疫组织化学结果与患者临床病理特征之间未发现统计学上的显著相关性。
所得结果表明p73基因可能在结直肠癌进展中作为肿瘤抑制因子发挥作用。
