Transduction of KAI1/CD82 cDNA promotes hematogenous spread of human lung-cancer cells in natural killer cell-depleted SCID mice.

KAI1, which is identical to CD82, was initially identified as a metastasis-suppressor gene for human prostate cancer, and its expression is reported to be a favorable prognostic factor for operable human lung cancer. In this study, we examined the functional role of KAI1/CD82 in the late phase of metastatic spread of human lung-cancer cells. For this, KAI1/CD82 cDNA was introduced into KAI1/CD82 low-expressing human lung-cancer cell lines, SBC-3 and PC-14, and then the metastatic potential of the transformants was analyzed by i.v. inoculation of KAI1/CD82-transduced cells, SBC-3/KAI1 and PC-14/KAI1, into NK cell-depleted SCID mice. Contrary to our expectations, KAI1/CD82 gene transfer promoted multiorgan metastasis of i.v.-inoculated human lung-cancer cells, while s.c. tumor growth was unaffected. Cancer cells from metastatic tumors of NK cell-depleted SCID mice injected i.v. with SBC-3/KAI1 expressed appreciable cell-surface KAI1/CD82, and cells not expressing KAI1/CD82 (revertants) were not detected in the tumors. Our findings indicate that under conditions where the host's natural cytotoxicity is suppressed, KAI1/CD82 may enhance the formation of tumors by circulating lung-cancer cells at metastatic sites.     

Mutation and expression of the metastasis suppressor gene KAI1 in esophageal squamous cell carcinoma

BACKGROUND: KAI1/CD82, a tumor metastasis suppressor gene, is correlated inversely with the progression and invasion of several tumors. It also has been reported that the KAI1 gene is related to the tumor suppressor gene p53. This study was performed to clarify the correlation between KAI1/CD82 expression and clinicopathologic characteristics and p53 expression in patients with esophageal squamous cell carcinoma (ESCC). The authors also investigated mutation of the KAI1 gene coding region to determine whether this may reduce KAI1 expression in ESCC. METHODS: Using immunohistochemistry with anti-KAI1 polyclonal antibody and monoclonal antibody against p53, KAI1/CD82 and p53 expression were detected in 55 patients with ESCC who had undergone surgery. The authors examined the KAI1 gene mutation in 22 patients with ESCC by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and DNA sequencing. RESULTS: KAI1/CD82 expression was positive in 36 of 55 patients (65.5%). There was a significant inverse correlation between KAI1/CD82 expression and regional lymph node metastasis (P = 0.0045), distant metastasis (P = 0.0092), the number of lymph node metastases (P = 0.0019), and pathologic stage (P = 0.0046). The survival rates of KAI1/CD82 negative patients were poorer than those of positive patients (P = 0. 024). The correlation between KAI1 positive and p53 positive tumors was not statistically significant. None of the 22 patients with ESCC showed mutation of the KAI1 gene by PCR-SSCP. In one patient, there was polymorphism in the SSCP assay and DNA sequencing. CONCLUSIONS: The authors demonstrated immunohistochemically that the expression of KAI1 protein appeared to be correlated with lymph node metastasis. Mutation does not seem to be a mechanism for dysregulation of the KAI1 protein in ESCC.     

The palmitoylation of metastasis suppressor KAI1/CD82 is important for its motility- and invasiveness-inhibitory activity

The cancer metastasis suppressor protein KAI1/CD82 is a member of the tetraspanin superfamily. Recent studies have demonstrated that tetraspanins are palmitoylated and that palmitoylation contributes to the organization of tetraspanin webs or tetraspanin-enriched microdomains. However, the effect of palmitoylation on tetraspanin-mediated cellular functions remains obscure. In this study, we found that tetraspanin KAI1/CD82 was palmitoylated when expressed in PC3 metastatic prostate cancer cells and that palmitoylation involved all of the cytoplasmic cysteine residues proximal to the plasma membrane. Notably, the palmitoylation-deficient KAI1/CD82 mutant largely reversed the wild-type KAI1/CD82's inhibitory effects on migration and invasion of PC3 cells. Also, palmitoylation regulates the subcellular distribution of KAI1/CD82 and its association with other tetraspanins, suggesting that the localized interaction of KAI1/CD82 with tetraspanin webs or tetraspanin-enriched microdomains is important for KAI1/CD82's motility-inhibitory activity. Moreover, we found that KAI1/CD82 palmitoylation affected motility-related subcellular events such as lamellipodia formation and actin cytoskeleton organization and that the alteration of these processes likely contributes to KAI1/CD82's inhibition of motility. Finally, the reversal of cell motility seen in the palmitoylation-deficient KAI1/CD82 mutant correlates with regaining of p130(CAS)-CrkII coupling, a signaling step important for KAI1/CD82's activity. Taken together, our results indicate that palmitoylation is crucial for the functional integrity of tetraspanin KAI1/CD82 during the suppression of cancer cell migration and invasion.     

非小细胞肺癌中KAI1基因表达及其与P53的相关性研究

背景与目的近年研究表明,KAI1表达下调与多种肿瘤的转移有关,但其与非小细胞肺癌的关系研究较少,且导致其下调的机制尚未明确。本研究从mRNA和蛋白水平探讨KAI1基因在非小细胞肺癌组织中的表达与患者临床病理特征的关系及其与突变型P53蛋白表达的关系。方法采用RTPCR和Westernblot法,检测48例肺癌患者手术切除的新鲜癌组织标本中KAI1mRNA、KAI1/CD82及突变型P53蛋白的表达,20例肺部良性疾病组织和正常肺组织作为对照。结果肺癌组和对照组中KAI1mRNA的阳性率分别为52%和90%(P<0.01),KAI1/CD82蛋白的阳性率分别为48%和85%(P<0.01),突变型P53蛋白阳性率分别为65%和5%(P<0.01)。KAI1mRNA、KAI1/CD82和突变型P53蛋白阳性率与肺癌患者临床分期、细胞分化程度和淋巴结转移有密切关系(P<0.05或P<0.01)。肺癌组织中KAI1mRNA与KAI1/CD82表达呈密切相关性(P<0.01),KAI1/CD82与突变型P53蛋白的表达亦呈显著相关性(P<0.05),KAI1mRNA与突变型P53表达无明显相关性(P>0.05)。结论KAI1基因的低表达可能与非小细胞肺癌的发生、发展和转移有关;其下调的机制可能主要发生在转录水平并与p53基因有关,二者可能作为评估肺癌患者转移潜能的指标。     

KAI1/CD82 expression as a prognosic factor in sporadic colorectal cancer

BACKGROUND: Since its identification as a suppressor gene for prostate cancer metastasis, down-regulation of KAI1/CD82 in a variety of malignancies has been reported. MATERIALS AND METHODS: Using immunohistochemistry, we examined KAI1/CD82 expression in surgical specimens obtained from 70 patients with advanced colorectal cancer and its correlation with clinicopathological factors, to clarify their prognostic significance. RESULTS: KAI1/CD82 expression was positive in 55% of the 70 colorectal cancers. There were statistically significant correlations between KAI1/CD82 expression and Dukes' stage, venous invasion, lymph node metastasis, tumor differentiation and liver metastasis. The significant correlation between KAI1/CD82 expression and outcome among patients with Dukes' C cancer (p=0.024) is particularly noteworthy. On multivariate analysis, KAI1/CD82 expression and Dukes' stage were identified as significant and independent prognostic factors (p=0.006 and 0.045, respectively). CONCLUSION: KAI1/CD82 expression closely correlates with clinicopathological factors for colorectal cancers. KAI1/CD82 expression appears to be a useful prognostic marker.     

脂质体介导KAI1基因转染对小细胞肺癌NCI-H446细胞株的抑制作用

 目的　探讨新抑癌基因KAI1对小细胞肺癌NCI H4 4 6细胞株抑制增殖和浸润转移的作用。方法　用脂质体介导的基因转染方法 ,借助真核质粒表达载体 (PCMV NEO XhoI) ,将抑癌基因KAI1转入小细胞肺癌NCI H4 4 6细胞中 ,经G4 18筛选 ,获得稳定表达的细胞克隆。观察NCI H4 4 6细胞的生长 ,MTT法检测细胞体外增殖能力 ,流式细胞仪进行细胞凋亡分析 ,间接免疫荧光染色结合流式细胞仪检测转染前后细胞CD82蛋白的表达。免疫组化测定Myc及MMP 1(基质金属蛋白酶 1)的表达 ,放射免疫测定LN(层黏蛋白 )表达。结果　脂质体 KAI1基因转染的小细胞肺癌细胞CD82表达增加 ,细胞增殖能力下降 ,凋亡增加 ,癌基因Myc ,MMP 1及LN表达下降。 结论　抑癌基因KAI1抑制小细胞肺癌NCI H4 4 6细胞株的增殖 ,降低Myc ,MMP 1及LN的表达。     

Mutant human tumor suppressor p53 modulates the activation of mitogen-activated protein kinase and nuclear factor-kappaB, but not c-Jun N-terminal kinase and activated protein-1

The roles of the mitogen-activated kinase protein (MAPK) pathway, nuclear factor-kappa B (NF-kappaB), and activator protein-1 (AP-1) in cellular responses to growth factors and mitogen are well established. However, the manner by which these proliferative pathways are affected by the tumor suppressor protein p53 is not fully understood. We report here the results of an investigation of the status of p53 on two human melanoma cell lines with wild-type p53 (SK-Mel-186) or mutant p53 (SK-Mel-110). The basal levels of the activated extracellular-signal regulated kinases 1 and 2 (ERK1/2) were high in cells with wild-type p53, but low in cells with mutant p53. The 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced activation of ERK1/2 through the phosphorylation of threonine and tyrosine at 202 and 204, respectively, was demonstrated in both cell lines, however, in a discrete manner. TPA-induced activation of ERK1/2 was sustained in wild-type p53 cells, while only a transient activation was seen in mutant p53 cells. Inhibition of MAPK kinase (MEK), an upstream kinase, by U0126, blocked TPA-induced activation of ERK1/2 in wild-type p53 cells and in mutant p53 cells. Treatment of wild-type p53 (SK-Mel 186) cells with small interfering RNA (siRNA) of p53 displayed a transient induction of activation of ERK1/2 following TPA treatment, indicating that p53 has a role in the regulation of the activation of ERK1/2. NF-kappaB activity decreased significantly in cells with wild-type p53, while enhanced NF-kappaB activity was evident in cells with mutant p53. The expression of either wild-type or mutant p53 had a similar effect on TPA-induced Jun N-terminal kinase (JNK) activation, indicating specificity for the ERK pathway. Similarly, AP-1 binding activity showed a transient variation in both cell lines after TPA treatment but with different kinetics. These observations suggest that both wild-type and mutant p53 can modulate the activation pathways for ERK1/2, and NF-kappaB distinctively, while modulating the pathways of JNK and AP-1 similarly. These differences may influence cellular processes such as proliferation, differentiation, and apoptosis.     

Expression of KITENIN, a KAI1/CD82 binding protein and metastasis enhancer, in bladder cancer cell lines: relationship to KAI1/CD82 levels and invasive behaviour

KITENIN is a newly identified binding partner of the KAI1/CD82 metastasis suppressor. Recent studies using a mouse model of colon cancer, have suggested that KITENIN might be a metastasis enhancer whose functions are modulated by an interaction with KAI1/CD82. To begin exploration of the possible importance of KITENIN to human cancer, we examined KITENIN mRNA (by RT-PCR) and protein expression (by Western blotting) in a large series of bladder cancer cell lines, and then compared these levels to the expression of KAI1/CD82 and of previously determined in vitro invasive behaviour of these same cancer cell lines. We report that KITENIN was uniformly expressed in all cancer cell lines, but those lines in which KAI1/CD82 was not detected, had a higher in vitro invasive ability and altered actin organisation (as determined by fluorescence microscopy), than those lines in which KAI1/CD82 was present. Our data suggest that the relationship between KITENIN and KAI1/CD82 may be an important determinant of tumour cell behaviour.     

KAI1基因转染协同ATRA诱导对肺腺癌细胞株抑制作用的研究

目的 :探讨新抑癌基因KAI1与全反式维甲酸 (all trans retinoicacid ,ATRA)对肺腺癌A5 49细胞株抑制增殖和诱导分化的作用。方法 :用脂质体介导的基因转染方法 ,借助质粒表达载体 (PCMV NEO XhoI) ,将抑癌基因KAI1转入肺腺癌A5 49细胞中 ,经G418筛选 ,获得稳定表达的细胞克隆。用 10 6mol/LATRA作用于转染及未转染KAI1基因的肺腺癌A5 49细胞株 ,MTT法检测细胞体外增殖能力 ,流式细胞仪进行细胞周期和凋亡分析 ,间接免疫荧光染色结合流式细胞仪检测转染前后细胞CD82 蛋白的表达。免疫组化测定myc、基质金属蛋白酶 (MMP 1)的表达 ,放射免疫测定层连蛋白(LN)表达。结果 :ATRA处理KAI1基因转染的肺腺癌细胞CD82 表达降低 ,细胞增殖能力下降 ,凋亡增加 ,更多的细胞被阻止于G1/G0 期 ,myc、MMP 1及LN表达下降 ,比对照组及单纯转染组细胞差异有统计学意义 ,P <0 0 5。结论 :抑癌基因KAI1与ATRA对抑制肺腺癌A5 49细胞株的增殖浸润转移有协同作用。     

Interaction of Duffy antigen receptor for chemokines and KAI1: a critical step in metastasis suppression

Tumor metastases suppressor protein KAI1/CD82 is capable of blocking the tumor metastases without affecting the primary tumor formation, and its expression is significantly down-regulated in many types of human cancers. However, the exact molecular mechanism of the suppressor function of KAI1 remains elusive. Evidence from our laboratory supports a model in which tumor cells dislodge from the primary tumor and intravasate into the blood or lymphatic vessels followed by attachment to the endothelial cell surface whereby KAI1 interacts with the Duffy antigen receptor for chemokines (DARC) protein. This interaction transmits a senescent signal to cancer cells expressing KAI1, whereas cells that lost KAI1 expression can proliferate, potentially giving rise to metastases. Our model of the mechanism of action of KAI1 shows that metastasis suppressor activity can be dependent on interaction with host tissue and explains how KAI1 suppresses metastasis without affecting primary tumor formation. Taken together, in vitro and in vivo studies identify the KAI1-DARC interaction as a potential target for cancer therapy.     

KAI1/CD82蛋白表达与食管癌淋巴结转移的关系

目的　探讨KAI1/CD82蛋白表达与食管癌淋巴结转移的关系。方法　应用免疫组化SABC法 ,检测 5 2例食管癌组织中KAI1/CD 82蛋白表达水平。结果　有淋巴结转移食管癌组织和无淋巴结转移食管癌组织中KAI1/CD 82蛋白表达率分别为2 8.6% ( 4 /14 )、73 .7% ( 2 8/3 8) ,两者比较有显著性差异 (P <0 .0 5 )。结论　KAI1/CD 82蛋白表达与食管癌淋巴结转移密切相关     

Tetraspanin KAI1/CD82 suppresses invasion by inhibiting integrin-dependent crosstalk with c-Met receptor and Src kinases

KAI1/CD82, a tetraspanin protein, was first identified as a metastasis suppressor in prostate cancer. How loss of CD82 expression promotes cancer metastasis is unknown. Restoration of CD82 expression to physiological levels in the metastatic prostate cell line PC3 inhibits integrin-mediated cell migration and invasion, but does not affect integrin expression. Integrin-dependent activation of the receptor kinase c-Met is dramatically reduced in CD82-expressing cells, as is c-Met activation by its ligand HGF/SF. CD82 expression also reduced integrin-induced activation and phosphorylation of the cytoplasmic tyrosine kinase Src, and its downstream substrates p130Cas and FAK Y861. Inhibition of c-Met expression or Src kinase function reduced matrigel invasion of PC3 cells to the same extent as CD82 expression. These data indicate that CD82 functions to suppress integrin-induced invasion by regulating signaling to c-Met and Src kinases, and suggests that CD82 loss may promote metastasis by removing a negative regulator of c-Met and Src signaling.     

Fas-mediated apoptosis is dependent on wild-type p53 status in human cancer cells expressing a temperature-sensitive p53 mutant alanine-143

The p53 mutant 143Ala is a human temperature-sensitive mutant with two conformational states.To definitively determine whether the Fas signal transduction pathway and the function of the pathway are dependent on p53 status, we have established stable transfectants of p53 mutant 143Ala in two human cancer cell lines: H1299 (lung cancer line) and PC-3 (prostate cancer line), the native state of which contains null p53 status and can grow at 37 degrees C and 32.5 degrees C. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell cycle analysis showed inhibition of the growth of cells overexpressing p53 mutant 143Ala in the wild-type p53 form at 32.5 degrees C because of induction of G0/G1 arrest. Transfected cells had increased protein expression of p21, Fas, and MDM2 at the wild-type p53 conformation at 32.5 degrees C, but not in the mutant p53 form at 37 degrees C. However, there was no change in protein expression of FADD, FAP-1, Bcl-2, or Bax at 32.5 or 37 degrees C. Assays for apoptosis demonstrated that anti-Fas antibody CH-11 and FasL induced apoptosis only in cells that overexpress p53 mutant 143Ala at 32.5 degrees C with the wild-type p53 form. Both caspase-3 and caspase-8 activities were increased by anti-Fas antibody CH-11 only in cells at 32.5 degrees C with wild-type p53. Our results demonstrated that Fas-mediated apoptosis in H1299 and PC-3 cells expressing p53 mutant 143Ala occurred only with the wild-type p53 phenotype. These results support the hypothesis that Fas-mediated apoptosis is dependent, at least partially, on the presence of a functional wild-type p53 state. This model may be a useful tool for dissecting the specific interactions between wild-type p53 and the Fas signal transduction pathway in human cancer cells.     

rAd-p53联合顺铂对胃癌细胞生长及 KAI1／CD82蛋白表达的影响

目的：观察rAd-p53、顺铂（ DDP）单独及联合作用于人胃癌SGC7901细胞后,对肿瘤细胞增殖凋亡情况、KAI1／CD82蛋白表达情况的影响。方法 rAd-p53、DDP单独及联合作用于胃癌SGC7901细胞株24、48、72 h后,CCK-8法测定SGC7901细胞体外增殖活性,流式细胞术检测细胞凋亡率,免疫组化法检测KAI1／CD82蛋白表达情况。结果rAd-p53、DDP单独及联合作用于SGC7901细胞后,细胞增殖被抑制,并呈剂量和时间依赖性,且两药联合组细胞增殖抑制率明显高于单用组,与阴性对照组相比差异均有统计学意义（ P＜0．05）;rAd-p53、DDP单独及两药联合作用SGC7901细胞48h后,细胞凋亡率为36．94％±0．78％、28．79％±2．37％,69．26％±0．63％;rAd-p53、DDP单独及两药联合均可上调KAI1／CD82蛋白表达,且两药联合组更明显。结论 rAd-p53、DDP单独及两药联合均可抑制胃癌SGC7901细胞的生长,诱导其凋亡,二者联合对胃癌细胞的抑制作用增强,rAd-p53可能通过上调KAI1／CD82的表达诱导SGC7901细胞凋亡,同时增强DDP的抗肿瘤作用。     

Adenoviral transduction of MRP-1/CD9 and KAI1/CD82 inhibits lymph node metastasis in orthotopic lung cancer model

Conventional therapies still remain less effective for metastasis of lung cancer, thus leading to a poor prognosis for this disorder. Although the processes involved in metastasis have not yet been clearly elucidated, our previous studies have shown that higher expression levels of MRP-1/CD9 and KAI1/CD82 in cancer cells are significantly correlated with less metastatic potency. To determine whether the gene transfer of these tetraspanins into lung tumor cells may be a useful strategy to regulate metastasis, we adopted an orthotopic lung cancer model produced by the intrapulmonary implantation of Lewis lung carcinoma (LLC) cells and evaluated the metastatic growth in the mediastinal lymph nodes using two different methods of gene delivery as follows: (a) the implantation of LLC cells preinfected with adenovirus encoding either MRP-1/CD9 cDNA, KAI1/CD82 cDNA, or LacZ gene into the mouse lung and (b) the intratracheal administration of these adenoviruses into the mice orthotopically preimplanted with LLC cells. In both cases, we found that the delivery of either MRP-1/CD9 or KAI1/CD82 cDNA dramatically reduced the metastases to the mediastinal lymph nodes in comparison with those of LacZ gene delivery, without affecting the primary tumor growth at the implanted site. These results reemphasize the important role of MRP-1/CD9 and KAI1/CD82 in the suppression of the metastatic process and also show the feasibility of gene therapy when using these tetraspanins for lung cancer to prevent metastasis to the regional lymph nodes. This strategy may therefore be clinically applicable as a prophylactic treatment to suppress the occurrence of lymph node metastasis.