Macwan Rajsumeet S, Ferrero Giulio, Pardini Barbara, Naccarati Alessio, Kozlowski Piotr B, Papetti Michael J
Touro College of Pharmacy, New York, NY 10036, USA.
Department of Clinical and Biological Sciences, University of Turin, Turin, Italy; Department of Computer Science, University of Turin, Turin, Italy.
Neoplasia. 2025 Jan;59:101093. doi: 10.1016/j.neo.2024.101093. Epub 2024 Nov 28.
The high morbidity and mortality associated with colorectal cancer (CRC) and the recent increases in early-onset CRC obviate the need for novel methods to detect and treat this disease, particularly at early stages. We hypothesize that aberrant expression of genes involved in the crypt-luminal migration of colon epithelial cells, a process necessary for their growth arrest and maturation, may disrupt differentiation and transition cells from a normal to tumorigenic state.
We searched for contractility- and motility-related genes that are dysregulated in human CRC relative to normal colon. RNA expression of one such gene, tropomyosin 4 (TPM4), was measured by qRT-PCR and RNA-seq in human colorectal tissues at various stages of tumorigenesis: CRC, adenoma, and at-risk (grossly normal mucosa from a patient with Familial Adenomatous Polyposis, or FAP), relative to controls. Effects of aberrant TPM4 expression on colon epithelial cell proliferation and maturation were determined by overexpression using stable transfection in spontaneously differentiating Caco2 cells or silencing using siRNA in proliferating cells.
TPM4 is overexpressed at various stages of tumorigenesis, including CRC, adenoma, and grossly normal FAP colon tissue, as well as in proliferating versus differentiating Caco2 cells. TPM4.2 overexpression in differentiating Caco2 cells markedly inhibits certain aspects of maturation, notably sucrase isomaltase and glutathione-S-transferase alpha1 expression, and causes morphological and cell junction abnormalities. Conversely, siRNA-mediated suppression of TPM4.2 inhibits Caco2 proliferation.
TPM4 overexpression attenuates colon epithelial cell differentiation and promotes proliferation. Therefore, TPM4 expression may be a biomarker to enhance strategies for CRC diagnosis and treatment.
结直肠癌（CRC）的高发病率和死亡率，以及近期早发性CRC的增加，凸显了开发新的CRC检测和治疗方法的必要性，尤其是在疾病早期阶段。我们推测，参与结肠上皮细胞隐窝-管腔迁移的基因异常表达，这一过程是其生长停滞和成熟所必需的，可能会破坏细胞分化，并使细胞从正常状态转变为致瘤状态。
我们搜索了与正常结肠相比在人类CRC中表达失调的与收缩性和运动性相关的基因。在肿瘤发生的各个阶段（CRC、腺瘤以及高危状态，即家族性腺瘤性息肉病患者的大体正常黏膜）的人类结直肠组织中，通过qRT-PCR和RNA测序测量了其中一个基因原肌球蛋白4（TPM4）的RNA表达，并与对照进行比较。通过在自发分化的Caco2细胞中进行稳定转染过表达或在增殖细胞中使用siRNA沉默来确定TPM4异常表达对结肠上皮细胞增殖和成熟的影响。
TPM4在肿瘤发生的各个阶段均过度表达，包括CRC、腺瘤以及大体正常的FAP结肠组织，以及在增殖的与分化的Caco2细胞中。在分化的Caco2细胞中过表达TPM4.2会显著抑制某些成熟方面，特别是蔗糖酶异麦芽糖酶和谷胱甘肽-S-转移酶α1的表达，并导致形态和细胞连接异常。相反，siRNA介导的TPM4.2抑制会抑制Caco2细胞增殖。
TPM4过表达会减弱结肠上皮细胞分化并促进增殖。因此，TPM4表达可能是一种生物标志物，可用于加强CRC的诊断和治疗策略。
