KAI1/CD82 expression in nonsmall cell lung carcinoma is a novel, favorable prognostic factor: an immunohistochemical analysis

Role of Metastasis Suppressor KAI1/CD82 in Different Cancers

Metastasis is one of the characteristics of malignant tumors and the main cause of death worldwide. The process of metastasis is mainly affected by tumor metastasis genes, tumor metastasis suppressor genes, tumor microenvironment, extracellular matrix degradation, and other factors. Thus, it is essential to elucidate the mechanism of metastasis and find the therapeutic targets in order to prevent the development of malignant tumors. KAI1/CD82, a member of tetraspanin superfamily of glycoproteins, has been reported as a tumor metastasis suppressor gene in various types of cancers without affecting the tumor formation. Many studies have demonstrated that low expression of KAI1/CD82 might lead to poor prognosis due to its interactions with other tetraspanins and integrins, resulting in the regulation of cell motility and invasion, cell-cell adhesion, and apoptosis. Considering its pathological and physiological significance, KAI1/CD82 could be a potential strategy for clinical predicting and preventing tumor progression and metastasis. The present review aims to discuss the role of KAI1/CD82 in metastasis for different cancers and examine its prospects as a metastasis biomarker and a therapeutic target.

Prognostic role of CD82/KAI1 in multiple human malignant neoplasms: a meta-analysis of 31 studies

Tetraspanin CD82, also known as KAI1, was revealed as an attractive prognostic tumor biomarker in recent studies. However, some results of these studies remained debatable and inconclusive. Therefore, we conducted a meta-analysis to clarify the precise predictive value of CD82 in various neoplasms. Qualified studies were identified up to April 27, 2017, by searching PubMed, EMBASE, and the Web of Science. In total, 29 eligible studies were ultimately enrolled in this meta-analysis. Pooled hazard ratios (HRs) with 95% CIs of overall survival and disease/recurrence/progression-free survival were calculated to evaluate the correct prognostic role of CD82. Statistical analysis demonstrated that high expression of CD82 was significantly associated with enhanced overall survival (HR =0.56, 95% CI: 0.47–0.67) and disease/recurrence/progression-free survival (HR =0.42, 95% CI: 0.30–0.59) in cancer patients. Furthermore, we also conducted the subgroup analysis and the results revealed that CD82 was associated with favorable outcomes in cancer patients. Taken together, CD82 could be a promising biomarker for predicting the prognosis of patients with malignant neoplasms, and the biological functions of CD82 are of great research value of the subject.

Frequency of Class I and II HLA alleles in patients with lung cancer according to chemotherapy response and 5-year survival

INTRODUCTION

Lung cancer is the most common cause of cancer death in the world, and the most common type is non-small-cell lung cancer (NSCLC). At present, surgical resection, chemotherapy, and radiation therapy are the main treatments for patients with NSCLC, but unfortunately outcome remains unsatisfactory.

OBJECTIVES

This study aimed to determine whether Class I and II histocompatibility leukocyte antigen (HLA) alleles are related with response to chemotherapy and survival of lung cancer.

METHODS

A total of 65 NSCLC patients (56 men and 9 women, mean age 58.4 ± 11 years) were included in the study. Patient groups were compared with a control group of 88 unrelated healthy kidney or bone marrow donors in order to clearly identify susceptible and protective HLA alleles in lung cancer. Target lesions and tumor response were assessed using the Response Evaluation Criteria for Solid Tumors (RECIST) guidelines. Results were classified into two groups: complete-partial response and stable-progressive disease.

RESULTS

We found that expression of HLA-A32, HLA-B41, HLA-B57, HLA-DRB1*13, and HLA-DQ5 were more frequent in the complete and partial response groups to chemotherapy than in the control group. The frequency of HLA-A11, HLA-A29, HLA-BW6, HLA-CW3, HLA-DR1*1, and HLA-DRB1*3 were determined to be higher in the stable and progressive disease groups taking chemotherapy than in the control group. Additionally, expressions of HLA-A2 and HLA-B49 were statistically related with 5-year survival.

CONCLUSION

Our results suggested that expressions of HLA-BW6 and HLA-DRB1*13 alleles may be predictable markers for response to chemotherapy in lung cancer patients.

Role of KAI1/CD82 polymorphisms in colon cancer risk in Han Chinese population

The aim of this study is to investigate the associations between KAI1/CD82 gene polymorphisms and colorectal cancer (CRC)-risk predisposition. We undertook a case-control study to analyze two KAI1/CD82 polymorphisms (exon 3 -29166 C>T and exon 9 -52840 C>A) in an Han Chinese population, by extraction of genomic DNA from the peripheral blood of 356 patients with CRC and 378 control participants, and performed KAI1/CD82 genotyping using DNA sequencing. The obtained results indicated that overall, no statistically significant association was observed in exon 9 (-52840 C>A). Nevertheless, exon 3 (-29166 C>T) genotype was at increased risk of CRC (P = 0.006; odds ratio = 1.299, CI 95% 1.058-1.549). Furthermore, -29166 T allele CRCs were more significantly common in patients with tumor size of >4 cm than C allele CRC and in cases of poor differentiation and advanced pathological stage. These findings led us to conclude that polymorphism in exon 3 (-29166 C>T) was observed to be associated with susceptibility of CRC. However, exon 9 (-52840 C>A) polymorphism showed no correlation to CRC susceptibility. Nevertheless, further investigation with a larger sample size is needed to support our results.

Tetraspanin CD82 inhibits protrusion and retraction in cell movement by attenuating the plasma membrane-dependent actin organization

To determine how tetraspanin KAI1/CD82, a tumor metastasis suppressor, inhibits cell migration, we assessed which cellular events critical for motility are altered by KAI1/CD82 and how KAI1/CD82 regulates these events. We found that KAI1/CD82-expressing cells typically exhibited elongated cellular tails and diminished lamellipodia. Live imaging demonstrated that the polarized protrusion and retraction of the plasma membrane became deficient upon KAI1/CD82 expression. The deficiency in developing these motility-related cellular events was caused by poor formations of actin cortical network and stress fiber and by aberrant dynamics in actin organization. Rac1 activity was reduced by KAI1/CD82, consistent with the diminution of lamellipodia and actin cortical network; while the growth factor-stimulated RhoA activity was blocked by KAI1/CD82, consistent with the loss of stress fiber and attenuation in cellular retraction. Upon KAI1/CD82 expression, Rac effector cofilin was not enriched at the cell periphery to facilitate lamellipodia formation while Rho kinase exhibited a significantly lower activity leading to less retraction. Phosphatidylinositol 4, 5-biphosphate, which initiates actin polymerization from the plasma membrane, became less detectable at the cell periphery in KAI1/CD82-expressing cells. Moreover, KAI1/CD82-induced phenotypes likely resulted from the suppression of multiple signaling pathways such as integrin and growth factor signaling. In summary, at the cellular level KAI1/CD82 inhibited polarized protrusion and retraction events by disrupting actin reorganization; at the molecular level, KAI1/CD82 deregulated Rac1, RhoA, and their effectors cofilin and Rho kinase by perturbing the plasma membrane lipids.

KAI1/CD82 decreases Rac1 expression and cell proliferation through PI3K/Akt/mTOR pathway in H1299 lung carcinoma cells

Although the KAI1/CD82 protein has been reported to inhibit cell metastasis in many studies, its mechanism of action has not yet been fully elucidated. In the present study, we investigated the possible effects of KAI1/CD82 on the metastatic phenotype in H1299 lung carcinoma cells. These studies were based on the pivotal role that the acquisition of motile phenotype plays on the initial steps of metastasis. KAI1/CD82-mediated morphological changes were observed using phase contrast microscopy. We report here, that a KAI1/CD82-induced phenotypic change was involved in the decrease of Rac1 expression and GTPase activity. However, we found that KAI1/CD82 did not regulate Rac1 mRNA levels. This suggests the existence of another regulatory mechanism of Rac1 protein maturation or activation. To identify the signaling pathway of Rac1 regulation, we investigated the PI3K/Akt/mTOR pathway, since the PI3K/Akt pathway regulates Rac1 activation and mTOR is known to play a regulatory role in protein translation. H1299/CD82-transfectants showed lower mTOR expression and cell growth than the control group. The data obtained from this study suggested that KAI1/CD82 decreased the metastatic phenotype of H1299 lung carcinoma cells by down-regulating Rac1 expression through the PI3K/Akt/mTOR pathway.

KAI1/CD82 suppresses hepatocyte growth factor-induced migration of hepatoma cells via upregulation of Sprouty2

We conducted a study concerning the suppressive mechanism of KAI1/CD82 on hepatoma cell metastasis. Hepatocyte growth factor (HGF) induces the migration of hepatoma cells through activation of cellular sphingosine kinase 1 (SphK1). Adenovirus-mediated gene transfer of KAI1 (Ad-KAI1) downregulates the SphK1 expression and suppresses the HGF-induced migration of SMMC-7721 human hepatocellcular carcinoma cells. Overexpression of KAI1/CD82 significantly elevates Sprouty2 at the protein level. Ablation of Sprouty2 with RNA interference can block the KAI1/CD82-induced suppression of hepatoma cell migration and downregulation of SphK1 expression. It is demonstrated that KAI1/CD82 suppresses HGF-induced migration of hepatoma cells via upregulation of Sprouty2.

Down-regulation of the metastasis suppressor protein KAI1/CD82 correlates with occurrence of metastasis, prognosis and presence of HPV DNA in human penile squamous cell carcinoma

In penile squamous cell carcinoma (PSCC), the outcome largely depends on early detection and resection of inguinal lymph node metastases. We investigated the role of metastasis suppressor protein kang ai 1 (KAI1)/cluster of differentiation 82 (CD82), which is known to be of prognostic significance for a wide variety of cancers. Moreover, we analysed the tumours for human papillomavirus (HPV) DNA and loss of heterozygosity at the 11p11.2 locus. Tissue samples of 30 primary PSCCs were investigated immunohistochemically using an anti-KAI1/CD82 polyclonal antibody. The expression was assessed according to the degree of KAI1/CD82-positive tumour cells as positive, decreased or negative. The presence of HPV6/11, HPV16 and HPV18 DNA was analysed by polymerase chain reaction. All patients with decreased or negative expression of KAI1/CD82 in primary lesions had lymph node metastases (p = 0.0002). Patients with positive KAI1/CD82 expression showed a significant better prognosis for survival compared to the other groups (p = 0.0042). Presence of HPV DNA was associated with decreased or negative KAI1/CD82 expression. Lacking or decreased expression of metastasis suppressor gene KAI1/CD82 appears to be a prognostic parameter for the occurrence of lymph node metastases in PSCC. Our study suggests an association of decreased KAI1/CD82 expression with tumour progression, development of metastases and disease-specific death.

Expression of human leucocyte antigen G (HLA-G) is associated with prognosis in non-small cell lung cancer

In a previous study, we demonstrated that human leucocyte antigen G (HLA-G) was aberrantly expressed in a majority of primary colorectal carcinomas, and that the detection of HLA-G expression had a strong and independent prognostic value in human colorectal cancer. In the current study, we look into whether the aberrant expression of HLA-G is also related to non-small cell lung cancer (NSCLC). The expression of HLA-G was investigated immunohistochemically in 106 patients with NSCLC. The correlation between HLA-G status and various clinicopathological parameters was analysed. As well, the level of HLA-G expression was also compared to the survival rate of patients with NSCLC. In total, we found that in 75% (79/106) of the primary site of NSCLC, an aberrant HLA-G expression was detected. However, this expression was not observed in the normal lung tissues. HLA-G expression in NSCLC was significantly correlated with lymph nodal metastasis, clinical stages of the disease, and host immune response (P = 0.0001, 0.0001, and 0.027, respectively). Patients with HLA-G positive tumours had a significantly shorter survival time than those with tumours that were HLA-G negative (P = 0.001). In addition, through multivariate analysis, HLA-G exhibited an independent prognostic factor (P = 0.01, relative risk 4.09; 95% confidence interval 1.40-11.9). All in all, our results indicate that the expression of HLA-G is a characteristic feature of NSCLC, and they suggest that immunostaining by anti-HLA-G antibodies may be a potentially useful prognostic indicator.

Colocalisation of CD9 and mortalin in CD9-induced mitotic catastrophe in human prostate cancer cells

CD9, a member of the tetraspanin family of proteins, is involved in a variety of cellular interactions with many other proteins and molecules. Although CD9 has been implicated in cell fusion, migration and cancer progression, the detailed function of this protein is not completely understood and likely depends on interactions with different protein partners, which are not yet all known. Using co-immunoprecipitation and mass-spectrometric protein sequencing, we have identified in prostate cancer cells, a novel CD9 partner, the 75-kDa protein HSPA9B, also known as mortalin. We further show that introduction and overexpression of wild-type CD9 into human PC-3 prostate cancer cells induces mitotic catastrophe. We also demonstrate, by immunocolocalisation studies, the interaction of CD9 and mortalin in PC-3 cells undergoing mitotic catastrophe. Our results not only identified mortalin as a new CD9 partner, but also clarify the mechanisms by which CD9 may control prostate cancer progression.

Clonal and parallel evolution of primary lung cancers and their metastases revealed by molecular dissection of cancer cells

PURPOSE

Several models of cancer progression, including clonal evolution, parallel evolution, and same-gene models, have been proposed to date. The purpose of this study is to investigate the authenticity of these models by comparison of accumulated genetic alterations between primary and corresponding metastatic lung cancers.

EXPERIMENTAL DESIGN

A whole-genome allelic imbalance scanning using a high-resolution single nucleotide polymorphism array and mutational analysis of the p53, EGFR, and KRAS genes were done on eight sets of primary and metastatic lung cancers. Based on the genotype data, the natural history of each case was deduced, and candidate metastasis suppressor loci were determined.

RESULTS

Five to 20 chromosomal regions showed allelic imbalance in each tumor. Accumulated genetic alterations were similar between primary and corresponding metastatic tumors, and the majority(>67%) of genetic alterations detected in metastatic tumors was also detected in the corresponding primary tumors. On the other hand, in seven of the eight cases, there were genetic alterations accumulated only in metastatic tumors. Among these alterations, allelic imbalances at chromosome 11p15 and 11p11-p13 regions were the most frequent ones (4 of 8, 50%). Likewise, four cases showed genetic alterations detected only in primary tumors.

CONCLUSIONS

The natural history of each case indicated that the process of metastasis varies among cases, and that all three models are applicable to lung cancer progression. According to the clonal and parallel evolution models, it is possible that a metastasis suppressor gene(s) for lung cancer is present on chromosome 11p.

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.

KAI1/CD82, a tumor metastasis suppressor

Tetraspanin KAI1/CD82 is a wide-spectrum tumor metastasis suppressor. KAI1/CD82 suppresses tumor metastasis by primarily inhibiting cancer cell motility and invasiveness. In tetraspanin-enriched microdomain, KAI1/CD82 associates with the proteins important for cell migration such as cell adhesion molecule, growth factor receptor, and signaling molecule. Likely, KAI1/CD82 down-regulates the functions of these motility-related proteins to inhibit cell migration. The loss of KAI1/CD82 expression in invasive and metastatic cancers is due to a complex, epigenetic mechanism that probably involves transcription factors such as NFkappaB, p53, and beta-catenin.

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.

Decreased expression of KAI1 metastasis suppressor gene is a recurrence predictor in primary pTa and pT1 urothelial bladder carcinoma

OBJECTIVE

To examine the expression of the KAI1 metastasis suppressor gene and to evaluate its relationship with tumor recurrence in primary pTa and pT1 urothelial bladder carcinoma.

METHODS

Samples were obtained from 87 patients after transurethral resection (TUR). Tumor stage and grade were reviewed in 33 patients with pTa and in 54 patients with pT1, with a mean follow-up time of 47.4 +/- 30.1 months. The KAI1 protein immunohistochemical assay was performed. Prognosis was analyzed using the Kaplan-Meier method and Cox's proportional hazards model. Correlation between KAI1 expression and recurrence according to each clinicopathological factor was comparatively evaluated using the chi-squared test.

RESULTS

Decreased expression of KAI1 protein failed to reach statistical significance for stage (P = 0.25) or morphology of tumor stem (P = 0.19), but it was significantly related to tumor size (P = 0.016). The recurrence-free 5-year survival rates of the group with decreased KAI1 expression was 69.7%, which was significantly higher than the 22.2% for the KAI1-positive group (P < 0.0001). In univariate and multivariate analyses, decreased expression of KAI1 protein, stage pT1, tumor size >3 cm and sessile tumors were independent prognosis factors of recurrence. Despite the lower recurrence rate expected by considering only the clinicopathological factors, decreased KAI1 expression was able to identify the group with a high risk of recurrence.

CONCLUSIONS

Downregulated KAI1 expression in bladder tumors tends to relate to stage and morphology of the tumor stem and was significantly correlated to tumor size. Decreased expression of KAI1 was associated with the degree of invasiveness and progression of the cancer and was an independent prognostic factor of recurrence in primary pTa and pT1 urothelial bladder carcinoma.

Co-downregulation of PTEN, KAI-1, and nm23-H1 tumor/metastasis suppressor proteins in non-small cell lung cancer

The multistep process of carcinogenesis implies the accumulation of multiple molecular defects. Alteration of tumor suppressor and metastasis suppressor genes are the important steps. Increasing experimental evidence indicates that decreased expression of tumor-metastasis/suppressor genes and gene products are involved in the progression of a variety of human malignancies. In the present study, we have extended this analysis to non-small cell lung carcinomas (NSCLC). The expression and prognostic significance of the tumor suppressor gene PTEN and metastasis suppressor genes nm23-H1 and KAI-1 was evaluated in NSCLCs. Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded tissues from 53 bronchogenic adenocarcinomas and 51 squamous cell carcinomas using monoclonal antibodies against PTEN, nm23H-1, and KAI-1 proteins. Immunohistochemical results were correlated with tumor stage, grade, lymph nodes positivity, metastasis, and patient survival. Significant co-expression of PTEN, nm23-H1 and KAI-1 was observed in NSCLC (P<.001 to .002). The immunohistochemical expression of these proteins was significantly higher in stages 1 and 2 compared with stages 3 and 4 (P=.04 for PTEN and KAI-1, P=.039 for nm23-H1). When all stages were considered together, loss of immunoreactivity for PTEN, nm23-H1 and KAI-1 was found in advanced NCSCLs (P=.015 for PTEN, P=.001 for KAI-1, P=.004 for nm23-H1), which is suggestive of co-downregulation of these proteins in the process of tumor progression. On multivariate analysis, negative staining for PTEN (P=.014), KAI-1 (P=.034), and nm23-H1 (a trend toward association for nm23-H1 reached near significance P=.08) correlated with disease-related death. Positive lymph node status was associated with negative immunostaining for PTEN (P=.007) but no correlation was observed for nm23-H1 and KAI-1. Loss of expression was linked to distant metastasis (P=.006 for PTEN, P=.002 for nm23H1, P=.001 for KAI-1). On multivariate analysis, co-downregulation of PTEN (P=.009), KAI-1 (P=.02), and nm23-H1 (P=.011) independently predicted shortened survival in NSCLC. Although NSCLC exhibits strong co-expression of PTEN, nm23-H1 and KAI-1, there is a loss of these proteins in high-stage tumors. Co-downregulation of PTEN, KAI-1, and nm23-H1 significantly correlates with distant metastasis and predicts shortened survival. Our study supports a role of these tumor suppressor and metastasis suppressor genes in the evolution and progression of NSCLC.

KAI1 expression in thyroid neoplasms: its linkage with clinicopathologic features in papillary carcinoma

KAI1 is a metastasis suppressor gene located on human chromosome 11p11.2. Previous studies have shown that the down-regulation of KAI1 mRNA and decreased expression of its gene product are significantly linked to carcinoma progression, including metastatic ability. In this study, we investigated KAI1 protein expression in thyroid neoplasms. KAI1 overexpression was observed in 64.0% of papillary carcinoma cases, and the incidence was significantly higher than in cases of follicular carcinoma (20.0%) (p = 0.0001). In papillary carcinomas, decreased KAI1 expression was frequently observed in cases invading beyond the thyroid capsule (p = 0.001), as well as in lymph node metastases (p = 0.0047) and poorly differentiated lesions (p = 0.0299). Furthermore, in anaplastic carcinoma, the incidence of KAI1 overexpression was lower than in papillary carcinoma (p < 0.0001), and only 4.2% of the cases overexpressed this gene. These results suggest that KAI1 down-regulation is significantly related to the progression of papillary carcinoma, including lymph node metastasis, and its anaplastic transformation.

Immunohistochemical typing of non-small cell lung cancer on cryostat sections: correlation with clinical parameters and prognosis

AIMS

To investigate the immunohistochemical expression of a panel of biologically relevant markers in patients with non-small cell lung cancer using fresh frozen specimens and to test their prognostic relevance for identification of patients at risk.

METHODS

Seventy nine tumour infiltrated lung cancer specimens and 66 adjacent histologically tumour free tissues were analysed; 11 postmortem specimens from patients who did not suffer from a malignant disease served as a control group. Cryostat sections were stained with monoclonal antibodies against epidermal growth factor receptor (EGFR), c-erbB-2, c-erbB-3, CD82, Ki-67, p120, p53, bcl-2, and CD31.

RESULTS

At least one of the tested markers was raised above the defined cut off point in 75 of the tumours. In 55, three to six factors were increased. EGFR was raised in 32, c-erbB-2 in 29, c-erbB-3 in 46, p53 in 29, bcl-2 in 26, Ki-67 in 36, p120 in 46, and CD31 in 29. None of the tested parameters was significant in univariate survival analysis. In a second step, three variables were combined (c-erbB3, p53, and microvessel density), and cases with increased expression of two or three parameters proved to have a significantly lower survival probability than those expressing none or only one factor. In the tumour free group only 10 showed raised marker expression.

CONCLUSION

Characterisation of tumour cells in surgical specimens with immunohistological markers could help identify those patients at risk for early cancer death who could possibly profit from adjuvant treatment after curative tumour resection.

Requirement of the p130CAS-Crk coupling for metastasis suppressor KAI1/CD82-mediated inhibition of cell migration

KAI1/CD82 protein is a member of the tetraspanin superfamily and has been rediscovered as a cancer metastasis suppressor. The mechanism of KAI1/CD82-mediated suppression of cancer metastasis remains to be established. In this study, we found that migration of the metastatic prostate cancer cell line Du145 was substantially inhibited when KAI1/CD82 was expressed. The expression of focal adhesion kinase (FAK) and Lyn, a Src family tyrosine kinase and substrate of FAK, was up-regulated at both RNA and protein levels upon KAI1/CD82 expression. The activation of FAK and Lyn, however, remained unchanged in Du145-KAI1/CD82 cells. As a downstream target of FAK-Lyn signaling, the p130CAS (Crk-associated substrate) protein was decreased upon the expression of KAI1/CD82. Consequently, less p130CAS-CrkII complex, which functions as a "molecular switch" in cell motility, was formed in Du145-KAI1/CD82 cells. To confirm that the p130CAS-CrkII complex is indeed important for the motility inhibition by KAI1/CD82, overexpression of p130CAS in Du145-KAI1/CD82 cells increased the formation of p130CAS-CrkII complex and largely reversed the KAI1/CD82-mediated inhibition of cell motility. Taken together, our studies indicate the following: 1) signaling of FAK-Lyn-p130CAS-CrkII pathway is altered in KAI1/CD82-expressing cells, and 2) p130CAS-CrkII coupling is required for KAI1/CD82-mediated suppression of cell motility.

KAI1/CD82 protein expression in primary prostate cancer and in BPH associated with cancer

Current prognostic methods in primary prostate cancer cannot accurately identify patients with clinically significant disease at highest risk of developing metastases. This study examined KAI1/CD82 metastasis suppressor expression by quantitative immunohistochemical analysis of benign prostatic hyperplasia (BPH) and prostate cancer specimens. Altogether, prostate cancers exhibited significant KAI1 overexpression compared to BPH not associated with cancer (P = 0.022). Increased KAI1 expression in well and moderately differentiated cancers, above levels seen in BPH, with decreased expression in poorly differentiated cancers was observed. Interestingly, KAI1 expression in BPH associated with cancers was significantly higher than in BPH not associated with cancer (P = 0.009). Thus, KAI1 overexpression may restrain onset and early stage prostate cancer development, whilst its loss may predispose the patient to more aggressive cancer behaviour. Altered KAI1 expression in prostate cancers and BPH associated with cancer may have important diagnostic roles.

Expression of metastasis suppressor gene (KAI1/CD82) in oral squamous cell carcinoma and its clinico-pathological significance

In this study, we investigated the expression of the KAI1/CD82 gene in oral squamous cell carcinoma (oral SCC). We studied 43 oral SCC patients. Reverse transcription-polymerase chain reaction (RT-PCR) analysis was performed to evaluate expression of this gene, and results were compared to the clinico-pathological findings. Twenty-five specimens (58.1%) were KAI1/CD82-positive, and 18 (41.9%) were negative. There were statistically significant relationships between gene expression and both histological malignancy (P=0.0205) and mode of invasion (P=0.0315). But there were no correlations of expression with tumor status, regional lymph node metastasis, pathological lymph node metastasis or histological differentiation. No significant relationship was observed between patient survival and expression of KAI1/CD82 by tumors. The results of this study suggest that the KAI1/CD82 gene may not be a useful predictor of prognosis, although decreased gene expression may be associated with increased invasive ability of oral SCC.

Loss of KAI1/CD82 expression in bone and soft tissue tumors is not associated with lung metastasis

The KAI1 gene has been identified as a metastasis suppressor gene in human prostate cancer. Decrease or loss of KAI1/CD82 expression has been shown to be associated with poorer prognosis and metastasis in carcinomas of various organs. The purpose of this study was to examine whether KAI1/CD82 is expressed in bone and soft tissue tumors, and whether it is associated with metastasis to the lungs. Immunohistochemically, KAI1/CD82 expression in benign and malignant soft tissue tumors was noted in 83% and 37% of cases, respectively. KAI1/CD82 was- also expressed in benign bone tumors and osteosarcomas in 67% and 36% of the cases, respectively. Four (40%) of 10 osteosarcoma cases with no lung metastasis and one (25%) of four osteosarcoma cases with lung metastasis were positive for KAI1/CD82, respectively. Metastasis of osteosarcoma cells to the lungs was not correlated with the loss of KAI1/CD82 in osteosarcoma cells.

KAI1, a prostate metastasis suppressor: prediction of solvated structure and interactions with binding partners; integrins, cadherins, and cell-surface receptor proteins

The solution structure of the transmembrane-4 superfamily protein KAI1, a recently identified prostate cancer metastasis suppressor gene that encodes a 267-amino acid protein, was modeled. The structure of this four-helical transmembrane protein was developed by defining and modeling sections individually. A complete three-dimensional structure for the solvated protein was developed by combining the individually modeled sections. The four-helix transmembrane bundle structure was predicted combining information from several methods including Fourier transform analysis of residue variability for helix orientation. The structure of the KAI1 large extracellular domain was modeled based on the solved crystal structure of the extracellular domain of another tetraspanin superfamily protein member, CD81 (hepatitis C virus envelope E2 glycoprotein receptor). This is a novel protein fold consisting of five alpha helices held together by two disulfide bonds for which the CD81 protein is the first solved representative. Molecular dynamics studies were performed to test stability and to relax the total model KAI1 structure's solution. The resulting KAI1 structural model should be a useful tool for predicting modes of self-association and associations with other TM4SF proteins, integrins, cadherins, and other KAI1 binding partners. Mutations for probing the interactions of KAI1 with antibodies and with other binding partners are suggested. Published 2001 Wiley-Liss, Inc.

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.

Expression of tumor-associated antigen RCAS1 correlates significantly with poor prognosis in nonsmall cell lung carcinoma

BACKGROUND

RCAS1 is a recently discovered antigen molecule expressed on the membrane of cancer cells, and it acts as a ligand for a putative receptor present on immune cells such as T, B and NK cells. It has been suggested that RCAS1 expression is related to the escape of tumors from immune surveillance. In this study, the relation between RCAS1 expression and various clinicopathologic variables, including patient prognosis, was investigated in lung carcinoma through immunohistochemical analysis.

METHODS

One hundred two surgically resected nonsmall cell lung carcinoma cases were examined histopathologically by means of the monoclonal antibody 22-1-1, which is specific for RCAS1. The correlation between RCAS1 expression and the clinicopathologic features of patients was evaluated. Moreover, the correlation between RCAS1 expression and the survival of patients was analyzed by the Kaplan-Meier method log-rank test, and multivariate analysis was performed by using the Cox proportional hazard model.

RESULTS

The samples of 48 of the 102 lung carcinoma patients (47.1%) were positive for RCAS1. There were significant correlations between RCAS1 expression and either pathologic staging (P = 0.0003) or tumor differentiation (P = 0.0308). The survival time for the RCAS1-positive group was significantly shorter than that for RCAS1-negative group (P < 0.0001). Moreover, multivariate analysis for overall survival revealed that RCAS1 expression was a significantly independent prognostic factor in nonsmall cell lung carcinoma patients.

CONCLUSION

These results suggested that RCAS1 expression may play an important role in the immune escape mechanism and that RCAS1 expression may be a good indicator of poor prognosis in patients with nonsmall cell lung carcinoma.

KAI1 gene is differently expressed in papillary and pancreatic cancer: influence on metastasis

AIM:To compare KAI1 in cancer of papilla of Vater and pancreas to evaluate whether there are differences in biologic behavior which might account for prognosis.METHODS:We compared the expression in 24 papillay and 29 pancreatic cancers using Northern blot analysis, immunochemical assay and in situ hybridization, and investigated whether early diagnosis or molecular differences predict the outcome in these tumor entities.RESULTS:By Northern blot analysis there is no statistical difference of KAI1 levels in normal and cancerous papilla. No association between KAI1 mRNA expression and tumor stage or tumor differentiation was found in the tumors. By immunohistochemical assay, KAI1 staining in cytoplasm of papillary cancer cells was similar to that of normal papillary cells. By in situ hybridization, the results of KAI1 mRNA expression in normal and cancerous papilla were similar to those with immunohistochemical assay. The normal and cancerous pancreas tissues were also analyzed by the methods used in papillary samples.CONCLUSION:Although the biologic roles of KAI1 have not been clarified, our results suggest that KAI1 may restrict the progression of malignant papillary cancer, but its expression might not have any effect on the characteristics of papillary tumor, whereas by the analysis of KAI1 gene, its reduced expression is closely related to the progression and metastases of pancreatic cancer.

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.

Frequent down-regulation and lack of mutation of the KAI1 metastasis suppressor gene in epithelial ovarian carcinoma

OBJECTIVE

KAI1 is a recently identified metastasis suppressor gene on human chromosome 11p11.2. It belongs to a structurally distinct family of cell surface glycoproteins. Decreased KAI1 expression seems to be involved in the progression of human prostate, lung, pancreatic, and possibly breast cancer, and recently a reduced KAI1 protein expression has been demonstrated in several ovarian carcinoma cell lines. The aim of this study is to determine whether the KAI1 gene is altered in human epithelial ovarian carcinomas. In addition, its prognostic significance in this tumor is also evaluated.

METHODS

To detect KAI1 expression, 102 tumor samples from benign, borderline, primary invasive, metastatic, and recurrent epithelial ovarian tumors were prepared for immunohistochemical study with C-16, an anti-KAI1 polyclonal antibody. In addition, cellular RNA from 24 primary invasive and 7 recurrent tumors was also analyzed for KAI1 expression by using a reverse transcriptase PCR (RT-PCR) technique. The PCR single-strand conformation polymorphism method and direct DNA sequencing were used to detect KAI1 mutation in the 44 primary invasive and 8 recurrent ovarian carcinomas.

RESULTS

In immunohistochemical study, decrease of KAI1 protein expression was associated with the progression of ovarian tumor. However, it had no relation to the stage of primary invasive cancers because of its frequent occurrence in early stage tumors. KAI1 expression was also frequently down-regulated in primary invasive and recurrent tumors in RT-PCR analysis. Except for a missense change at codon 241 (ATC to GTC), which causes the substitution of a valine for an isoleucine in the amino acid sequence and occurs in both normal and tumor tissues, no mutation of the KAI1 gene was found in any of the 52 carcinomas. Although there was a trend for deteriorating survival from patients with KAI1-preserved tumors to those with KAI1-decreased and -negative tumors, statistically it was not significant (P = 0.079).

CONCLUSION

KAI1 may play a role in the malignant progression of epithelial ovarian carcinoma through the down-regulation of expression rather than gene mutation. Since the decreased expression presented frequently in early stage tumors, it may be an early event in the progression of this tumor and its prognostic significance needs further investigation with a larger number of cases.

Relationship between expression of the KAI1 metastasis suppressor and other markers of advanced bladder cancer

Expression of a newly described inhibitor of tumour metastasis, KAI1, was examined in bladder cancer progression and compared with the expression of p53 and pRb, which are markers of advanced disease. KAI1 mRNA (by in situ hybridization) and protein levels (by immunohistochemistry) were examined in 135 paraffin-embedded bladder tissue sections. Significant decreases in KAI1 mRNA and protein levels were detected between normal and tumour tissue (p<0.001 and p=0.026, respectively), and between non-invasive and invasive tumours (p=0.046 and p<0.001, respectively). Loss of KAI1 protein expression was accompanied by a shift in staining pattern from a uniform distribution to a weaker, membranous or heterogeneous pattern. Normal tissue and low-grade tumours showed little p53 protein staining. High level staining (indicative of mutant p53) was associated with increased grade in non-invasive tumours (p=0.031) but was not significantly higher in invasive tumours. Whilst p53 protein staining increased with malignant progression and KAI1 mRNA expression decreased, there was no significant correlation between the two patterns (p=0.33, adjusted for group, p=0.18) or when only cancer samples were analysed (p=0.065, adjusted for group, p=0.26), even when taking into account overexpression of MDM-2 protein as a pathway for inactivation of p53. There was no correlation between loss of KAI1 mRNA expression and gain of abnormal pRb staining (p=0. 30, or adjusted for tumour samples only, p=0.59). These results suggest that loss of KAI1 expression is associated with invasive bladder cancer, but is not related to mutation of p53 or to loss of normal pRb expression.

Conventional clinicopathologic prognostic factors in surgically resected nonsmall cell lung carcinoma. A comparison of prognostic factors for each pathologic TNM stage based on multivariate analyses

BACKGROUND

A number of prognostic factors have been reported for resected nonsmall cell lung carcinoma. None of them, however, has been reported to have greater prognostic impact than the pathologic TNM staging system. The authors evaluated 18 conventional clinicopathologic prognostic factors in each pathologic stage.

METHODS

A retrospective study was conducted on surgically resected 836 lung carcinoma patients, and the following conventional prognostic factors were evaluated in multivariate analyses: age, gender, pack-year smoking, serum carcinoembryonic antigen and squamous cell carcinoma antigen levels, laterality of tumor, clinical N status, histologic type of tumor, greatest tumor dimension, grade of differentiation, pleural involvement, lymphatic invasion, vascular invasion, degree of fibrosing scarring, nuclear atypia, mitotic activity, and curativity of resection.

RESULTS

The overall 5-year survival rate was 63.8%. In 430 cases of pathologic Stage I disease, multivariate analyses revealed 3 significant prognostic factors: clinical N status (P < 0.001), vascular invasion (P = 0.001), and curativity of resection (P < 0.001). In 406 cases of more advanced disease, i.e., pathologic Stage II, IIIA, IIIB, or IV, multivariate analyses revealed 4 factors as significant: histology (P = 0.001), pathologic N status (P < 0.001), tumor size (P < 0.001), and curativity of resection (P = 0.002).

CONCLUSIONS

Conventional clinicopathologic prognostic factors had a different impact on prognosis in each pathologic TNM stage among patients who underwent surgical resection of nonsmall cell lung carcinoma. These factors should be analyzed separately in each pathologic TNM stage.

Down-regulation of KAI1 messenger RNA expression is not associated with loss of heterozygosity of the KAI1 gene region in lung adenocarcinoma

KAI1, a metastasis suppressor gene of prostate cancer, is located on human chromosome 11p11.2. Down-regulation of KAI1 mRNA during tumor progression and metastasis has been reported for several kinds of cancer, but the mechanism of this down-regulation is not known. In the present study, our aim was to ascertain the relationship between down-regulation of KAI1 mRNA expression and KAI1 gene alterations in lung cancer. Forty-nine cases of adenocarcinoma of the lung were studied by reverse-transcriptase polymerase chain reaction (RT-PCR) assay of KAI1 mRNA and by immunohistochemical detection of KAI1 protein. In addition, markers of the microsatellite loci D11S1344 and D11S1326 were used to investigate loss of heterozygosity (LOH) and replication errors (RERs) of the KAI1 gene region. The RT-PCR assay showed that there was no correlation between KAI1 mRNA expression and either the age of the patients or tumor size. By contrast, KAI1 mRNA expression was significantly correlated with gender (P=0.047), metastasis to the lymph nodes or other organs (P=0.004), the histological grade of the tumor (P=0.036) and the pathological stage (P=0.049). Immunohistochemical staining showed that in one case without metastasis, loss of KAI1 mRNA was associated with invasion of the stroma by KAI1 protein-negative cancer cells. The numbers of informative cases by microsatellite analysis were 14 (28.6%) of 49 at D11S1344 and 27 (55.1%) of 49 at D11S1326; none of 49 adenocarcinomas showed LOH or RERs at these loci. These results suggest that down-regulation of KAI1 mRNA expression rarely if ever involves LOH or RERs of the KAI1 gene region in primary lung adenocarcinoma.

Frequent loss of KAI1 expression in squamous and lymphoid neoplasms. An immunohistochemical study of archival tissues

The metastasis suppressor gene KAI1 was identified by its ability to inhibit the formation of pulmonary metastases in experimental models for prostatic carcinoma. Down-regulation of this gene may be correlated with the invasive phenotype in melanomas and colon and bladder carcinomas and with the metastatic phenotype in carcinomas of the lung, breast, prostate, and pancreas. The goal of our study was to establish an immunohistochemical method to detect KAI1 expression in archival tissues. Using cell lines with known KAI1 levels and paraffin-embedded KAI1 positive tissues as controls, we observed strong membrane staining in lymphoid follicular centers and squamous epithelia. We then demonstrated the utility of our assay by studying KAI1 expression in 34 lymphoid and 57 squamous lesions. All eight reactive lymph nodes were KAI1 positive. In contrast, three of 13 follicular small cleaved and five of 13 diffuse large cell lymphomas were KAI1 negative. Seventy-nine percent (37 of 47) of invasive squamous cell carcinomas from the lung (n = 15), head and neck (n = 18), and cervix (n = 14) showed extensive KAI1 down-regulation. Loss of KAI1 expression was also found in a subset of 10 high-grade cervical dysplasias. Our data show that (i) immunohistochemistry is a suitable technique for evaluating KAI1 expression in archival tissues; (ii) KAI1 was not expressed in a subset of both low-grade and high-grade lymphomas; and (iii) there was extensive down-regulation of KAI1 in squamous cell carcinomas, suggestive of an important role of the gene in the suppression of invasion in these malignancies.