Department of Dermatology and Venereology, Faculty of Medicine, Trakya University, Edirne, Turkey.
Department of Biophysics, Faculty of Medicine, Trakya University, Edirne, Turkey.
Mol Biol Rep. 2023 Sep;50(9):7295-7304. doi: 10.1007/s11033-023-08656-2. Epub 2023 Jul 10.
SMAD4 is a potent tumor suppressor. SMAD4 loss increases genomic instability and plays a critical role in the DNA damage response that leads to skin cancer development. We aimed to investigate SMAD4 methylation effects on mRNA and protein expression of SMAD4 in cancer and healthy tissues from patients with basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and basosquamous skin cancer (BSC).
The study included 17 BCC, 24 cSCC and nine BSC patients. DNA and RNA were isolated from cancerous and healthy tissues following punch biopsy. Methylation-specific polymerase chain reaction (PCR) and real-time quantitative PCR methods were used to examine SMAD4 promoter methylation and SMAD4 mRNA levels, respectively. The percentage and intensity of staining of the SMAD4 protein were determined by immunohistochemistry. The percentage of SMAD4 methylation was increased in the patients with BCC (p = 0.007), cSCC (p = 0.004), and BSC (p = 0.018) compared to the healthy tissue. SMAD4 mRNA expression was decreased in the patients with BCC (p˂0.001), cSCC (p˂0.001), and BSC (p = 0.008). The staining characteristic of SMAD4 protein was negative in the cancer tissues of the patients with cSCC (p = 0.00). Lower SMAD4 mRNA levels were observed in the poorly differentiated cSCC patients (p = 0.001). The staining characteristics of the SMAD4 protein were related to age and chronic sun exposure.
Hypermethylation of SMAD4 and reduced SMAD4 mRNA expression were found to play a role in the pathogenesis of BCC, cSCC, and BSC. A decrease in SMAD4 protein expression level was observed only in cSCC patients. This suggests that epigenetic alterations to the SMAD4 gene are associated with cSCC.
The name of the trial register: SMAD4 Methylation and Expression Levels in Non-melanocytic Skin Cancers; SMAD4 Protein Positivity. The registration number: NCT04759261 ( https://clinicaltrials.gov/ct2/results?term=NCT04759261 ).
SMAD4 是一种有效的肿瘤抑制因子。SMAD4 的缺失会增加基因组不稳定性，并在导致皮肤癌发展的 DNA 损伤反应中发挥关键作用。我们旨在研究 SMAD4 甲基化对基底细胞癌 (BCC)、皮肤鳞状细胞癌 (cSCC) 和基底鳞状皮肤癌 (BSC) 患者癌症和健康组织中 SMAD4mRNA 和蛋白表达的影响。
本研究纳入了 17 例 BCC、24 例 cSCC 和 9 例 BSC 患者。通过打孔活检从癌组织和健康组织中分离 DNA 和 RNA。采用甲基化特异性聚合酶链反应 (PCR) 和实时定量 PCR 方法分别检测 SMAD4 启动子甲基化和 SMAD4mRNA 水平。通过免疫组织化学法测定 SMAD4 蛋白的染色百分比和强度。与健康组织相比，BCC(p=0.007)、cSCC(p=0.004)和 BSC(p=0.018)患者的 SMAD4 甲基化百分比增加。BCC(p<0.001)、cSCC(p<0.001)和 BSC(p=0.008)患者的 SMAD4mRNA 表达降低。cSCC 患者的癌症组织中 SMAD4 蛋白的染色特征为阴性(p=0.00)。低分化 cSCC 患者的 SMAD4mRNA 水平较低(p=0.001)。SMAD4 蛋白的染色特征与年龄和慢性阳光暴露有关。
我们发现 SMAD4 的高甲基化和 SMAD4mRNA 表达降低在 BCC、cSCC 和 BSC 的发病机制中发挥作用。仅在 cSCC 患者中观察到 SMAD4 蛋白表达水平降低。这表明 SMAD4 基因的表观遗传改变与 cSCC 相关。
试验注册名称：非黑色素细胞皮肤癌中 SMAD4 甲基化和表达水平；SMAD4 蛋白阳性。注册号：NCT04759261(https://clinicaltrials.gov/ct2/results?term=NCT04759261)。
