Rajmani R S, Gandham Ravi Kumar, Gupta Shishir Kumar, Sahoo Aditya P, Singh Prafull Kumar, Saxena Shikha, Kumar Rajiv, Chaturvedi Uttara, Tiwari Ashok K
Molecular Biology Laboratory, Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh, India.
Cell Biol Int. 2015 Nov;39(11):1317-28. doi: 10.1002/cbin.10510. Epub 2015 Aug 3.
Nuclear factor kappa-B (NF-κB), a key anti-apoptotic factor, plays a critical role in tumor cell growth, metastasis, and angiogenesis. The transcriptional activity of NF-κB is normally suppressed in the cytoplasm due to its association with a natural inhibitor molecule IκB. Phosphorylation of the IκB at Ser 32 and Ser 36 by the IκB kinase complex (IKK) marks the degradation of the molecule by 26S proteasome. As NF-κB is constitutively activated in most of the tumor cells, inhibition of the activities of IKK may significantly sensitize the tumor cells to apoptosis. In the present study, we investigated the effect of IκB kinase-specific blocker PS1145 on DMBA-induced skin tumor of male Wistar rats. We examined the apoptotic effect of PS1145 on DMBA-induced tumor by various histopathological and molecular techniques. Our results demonstrate the significant expression of major pro-apoptotic genes like caspases 2, 3, 8, 9, and p53 in PS1145-treated tumor bearing group at mRNA levels as well as significant (P < 0.05) down regulation in the expression levels of NF-κB and VEGF, the major pro-inflammatory and pro-angiogenic factors, respectively. The histopathological examination showed that the tumor progression, mitotic, AgNOR, and PCNA indices were significantly reduced in PS1145 treatment groups as compared to PBS control on day 28 of post-treatment. Furthermore, significant increase in TUNEL positive nuclei and observation of peculiar apoptotic nuclei in transmission electron microscopy were seen in PS1145 treatment group. We conclude that intravenous application of PS1145 promotes direct apoptosis in DMBA-induced skin tumor in male Wistar rats by blocking NF-κB and VEGF activities.
核因子κB（NF-κB）是一种关键的抗凋亡因子，在肿瘤细胞的生长、转移和血管生成中起着至关重要的作用。由于NF-κB与天然抑制剂分子IκB结合，其转录活性通常在细胞质中受到抑制。IκB激酶复合物（IKK）使IκB的丝氨酸32和丝氨酸36磷酸化，标志着该分子被26S蛋白酶体降解。由于NF-κB在大多数肿瘤细胞中持续激活，抑制IKK的活性可能会使肿瘤细胞对凋亡显著敏感。在本研究中，我们研究了IκB激酶特异性阻滞剂PS1145对雄性Wistar大鼠二甲基苯并蒽（DMBA）诱导的皮肤肿瘤的影响。我们通过各种组织病理学和分子技术检查了PS1145对DMBA诱导肿瘤的凋亡作用。我们的结果表明，在mRNA水平上，PS1145处理的荷瘤组中主要促凋亡基因如半胱天冬酶2、3、8、9和p53有显著表达，并且NF-κB和VEGF（主要的促炎和促血管生成因子）的表达水平分别有显著（P < 0.05）下调。组织病理学检查显示，与治疗后第28天的PBS对照组相比，PS1145治疗组的肿瘤进展、有丝分裂、核仁组成区嗜银蛋白（AgNOR）和增殖细胞核抗原（PCNA）指数显著降低。此外，在PS1145治疗组中观察到TUNEL阳性细胞核显著增加，并且在透射电子显微镜下观察到特殊的凋亡细胞核。我们得出结论，静脉注射PS1145通过阻断NF-κB和VEGF的活性促进雄性Wistar大鼠DMBA诱导的皮肤肿瘤中的直接凋亡。
