探讨干扰素诱导蛋白6 （IFI6）在肾细胞癌（RCC）进展中的作用及其介导舒尼替尼（sunitinib）耐药的分子机制。

基于TCGA数据库及临床样本，分析IFI6在RCC与癌旁组织中的表达差异。在人RCC细胞786-O、ACHN中，转染siRNA阴性对照（scramble）及IFI6 siRNA （siIFI6），采用CCK-8、Transwell实验比较对照组和敲低组的细胞增殖、迁移和侵袭功能变化；Western blot分析凋亡标志物变化（caspase3、cleaved caspase3、Bcl2、BAX）。检测sunitinib耐药株786-O-SuR中IFI6表达水平；分析IFI6敲低对sunitinib半数抑制浓度（IC₅₀）的影响。通过构建IFI6敲低（shRNA）的OSRC-2稳定转染细胞系，进行裸鼠皮下成瘤实验，并结合sunitinib处理，以验证其在体内的效果。实验分为四组：scramble + DMSO组、shIFI6 + DMSO组、scramble + sunitinib组和shIFI6 + sunitinib组。两组间比较采用独立样本t检验，配对样本比较采用配对样本t检验，多组间比较采用单因素方差分析，组间两两比较采用Dunnett-t检验。

与癌旁组织相比，癌组织中IFI6在RCC中高表达，且高表达患者预后不良（P < 0.05）。转染siIFI6后，与scramble组相比，siIFI6-1、siIFI6-2组的细胞增殖[786-O：（1.33 ± 0.11）、（1.24 ± 0.11）比（2.15 ± 0.15）；ACHN：（2.03 ± 0.14）、（1.59 ± 0.14）比（3.05 ± 0.18）]减少，迁移[786-O：（169.67 ± 31.01）、（140.67 ± 19.40）比（371.67 ± 58.05）个；ACHN：（245.67 ± 33.25）、（177.33 ± 18.45）比（558.00 ± 83.83）个]及侵袭能力[786-O：（55.33 ± 9.07）、（46.67 ± 7.77）比（102.00 ± 8.54）个；ACHN：（43.33 ± 12.66）、（37.33 ± 11.93）比（118.00 ± 12.49）个]下降（P均< 0.05）。IFI6敲低导致cleaved caspase3与BAX表达升高，而总caspase3与Bcl2表达降低。与786-O细胞相比，786-O-SuR细胞中IFI6的mRNA和蛋白水平升高（P均< 0.05）。与scramble组相比，siIFI6-1、siIFI6-2组在786-O、ACHN和786-O-SuR细胞中sunitinib IC₅₀浓度[786-O：（5.02 ± 0.15）、（4.40 ± 0.47）比（7.28 ± 0.28）μmol/L；ACHN：（4.56 ± 0.17）、（4.20 ± 0.19）比（6.68 ± 0.31） μmol/L；786-O-SuR：（8.02 ± 0.45）、（7.50 ± 0.49）比（16.61 ± 1.16） μmol/L]下降（P均< 0.05）。裸鼠体内成瘤实验显示：scramble + sunitinib组、shIFI6 + DMSO组较scramble + DMSO组肿瘤质量与体积[质量：（318.36 ± 40.81）、（308.54 ± 36.97）比（532.76 ± 79.59）mg，体积：（362.68 ± 58.76）、（349.96 ± 59.38）比（681.20 ± 150.85）mm³]减小（P均< 0.05），且shIFI6 + sunitinib组较scramble + sunitinib组[质量：（109.28 ± 34.43）比（318.36 ± 40.81）mg，体积：（112.04 ± 40.62）比（362.68 ± 58.76）mm³]进一步减小（P均< 0.05）。

IFI6通过抑制凋亡促进RCC进展及sunitinib耐药，靶向IFI6可增强药物敏感性，本研究具有潜在临床转化价值。

To investigate the role of interferon-induced protein 6 (IFI6) in renal cell carcinoma (RCC) progression and the molecular mechanism in sunitinib resistance.

The differences of IFI6 expression between tumor and normal tissues were analyzed using TCGA data and clinical samples. The human RCC cells (786-O and ACHN) was transfected with either non-targeting siRNA control (scramble) or IFI6 siRNA (siIFI6). Cell proliferation, migration, and invasion were comparatively assessed between control and knockdown groups using CCK-8 and Transwell assays. Apoptosis-related proteins (caspase3、cleaved caspase3、Bcl2、BAX) were detected via Western blot. IFI6 expression was measured in sunitinib-resistant cells (786-O-SuR), and the changes in the half maximal inhibitory concentration (IC₅₀) of sunitinib were evaluated after IFI6 knockdown. Stable OSRC-2 cell lines with IFI6 knockdown (shIFI6) were established, and a subcutaneous tumor xenograft model in nude mice was performed with sunitinib treatment to evaluate its in vivo efficacy. The experiment was divided into four groups: scramble + DMSO, shIFI6 + DMSO, scramble + sunitinib, and shIFI6 + sunitinib. Independent samples t-test was used for comparisons between two groups, and paired samples t-test was used for paired comparisons. For comparisons among three or more groups, one-way ANOVA was employed. Dunnett's t-test was used for pairwise comparison between groups.

IFI6 was significantly upregulated in RCC tissues versus normal tissues (P < 0.05), with high expression correlating with poor prognosis (P < 0.05). IFI6 knockdown markedly suppressed the abilities of proliferation [786-O: (1.33 ± 0.11), (1.24 ± 0.11) vs (2.15 ± 0.15) ; ACHN: (2.03 ± 0.14), (1.59 ± 0.14) vs (3.05 ± 0.18) ; P < 0.05], migration [786-O: (169.67 ± 31.01), (140.67 ± 19.40) vs (371.67 ± 58.05) cells; ACHN: (245.67 ± 33.25), (177.33 ± 18.45) vs (558.00 ± 83.83) cells; P < 0.05], and invasion [786-O: (55.33 ± 9.07), (46.67 ± 7.77) vs (102.00 ± 8.54) cells; ACHN: (43.33 ± 12.66), (37.33 ± 11.93) vs (118.00 ± 12.49) cells; P < 0.05]. Knockdown of IFI6 led to an increased expression of cleaved caspase 3 and BAX, while the expression of total caspase 3 and Bcl2 was decreased. Compared with 786-O, the expression levels of IF16 mRNA and protein were elevated in 786-O-SuR (P < 0.05 for both). The IC₅₀ concentration of sunitinib in the siIFI6-1 and siIFI6-2 groups was significantly lower than that in the Scramble group in 786-O, ACHN and 786-O-SuR cells [ 786-O: (5.02 ± 0.15), (4.40 ± 0.47) vs (7.28 ± 0.28) μmol/L; ACHN: (4.56 ± 0.17), (4.20 ± 0.19) vs (6.68 ± 0.31) μmol/L; 786-O-SuR: (8.02 ± 0.45), (7.50 ± 0.49) vs (16.61 ± 1.16) μmol/L; P < 0.05 for all ]. In vivo tumor formation experiments in nude mice revealed that, the tumor mass and volume in the Scramble + Sunitinib group and shIFI6 + DMSO group were significantly smaller than those in the Scramble + DMSO group [mass: (318.36 ± 40.81), (308.54 ± 36.97) vs (532.76 ± 79.59) mg, volume: (362.68 ± 58.76) and (349.96 ± 59.38) vs (681.20 ± 150.85) mm³; P < 0.05 for all], and the tumor mass and volume in the shIFI6 + Sunitinib group were further reduced compared with the Scramble + Sunitinib group [mass: (109.28 ± 34.43) vs (318.36 ± 40.81) mg, volume: (112.04 ± 40.62) vs (362.68 ± 58.76) mm³; P < 0.05 for all ].

This study reveals that IFI6 promotes RCC progression and confers sunitinib resistance by suppressing apoptosis. Targeting IFI6 sensitizes RCC to therapeutic agents, demonstrating potential clinical significance.