High-density allelotyping of chromosome 8p in hepatocellular carcinoma and clinicopathologic correlation

Establishment and characterization of a highly metastatic hepatocellular carcinoma cell line

The prevalence of alcohol-related hepatocellular carcinoma (HCC) has been increasing during the last decade. Cancer research requires cell lines suitable for both in vitro and in vivo assays. However, there is a lack of cell lines with a high in vivo metastatic capacity for this HCC subtype. Herein, a new HCC cell line was established, named HCC-ZJ, using cells from a patient diagnosed with alcohol-related HCC. The karyotype of HCC-ZJ was 46, XY, del (p11.2). Whole-exome sequencing identified several genetic variations in HCC-Z that occur frequently in alcohol-associated HCC, such as mutations in TERT, CTNNB1, ARID1A, CDKN2A, SMARCA2, and HGF. Cell counting kit-8 assays, colony formation assays, and Transwell assays were performed to evaluate the proliferation, migration, and sensitivity to sorafenib and lenvatinib of HCC-Z in vitro. HCC-ZJ showed a robust proliferation rate, a weak foci-forming ability, a strong migration capacity, and a moderate invasion tendency in vitro. Finally, the tumorigenicity and metastatic capacity of HCC-Z were evaluated using a subcutaneous xenograft model, an orthotopic xenograft model, and a tail-veil injection model. HCCZJ exhibited strong tumorigenicity in the subcutaneous xenograft and orthotopic tumor models. Moreover, HCC-ZJ spontaneously formed pulmonary metastases in the orthotopic tumor model. In summary, a new HCC cell line derived from a patient with alcohol-related HCC was established, which showed a high metastatic capacity and could be applied for in vitro and in vivo experiments during pre-clinical research.Highlights• An alcohol-related HCC cell line, HCC-ZJ, was established• HCC-ZJ was applicable for in vitro functional experiment and gene editing• HCC-ZJ was applicable for in vivo tumor growth and spontaneous metastasis models.

An integrative view on glucagon function and putative role in the progression of pancreatic neuroendocrine tumours (pNETs) and hepatocellular carcinomas (HCC)

Cancer metabolism research area evolved greatly, however, is still unknown the impact of systemic metabolism control and diet on cancer. It makes sense that systemic regulators of metabolism can act directly on cancer cells and activate signalling, prompting metabolic remodelling needed to sustain cancer cell survival, tumour growth and disease progression. In the present review, we describe the main glucagon functions in the control of glycaemia and of metabolic pathways overall. Furthermore, an integrative view on how glucagon and related signalling pathways can contribute for pancreatic neuroendocrine tumours (pNETs) and hepatocellular carcinomas (HCC) progression, since pancreas and liver are the major organs exposed to higher levels of glucagon, pancreas as a producer and liver as a scavenger. The main objective is to bring to discussion some glucagon-dependent mechanisms by presenting an integrative view on microenvironmental and systemic aspects in pNETs and HCC biology.

The association of lncRNA SNPs and SNPs-environment interactions based on GWAS with HBV-related HCC risk and progression

Background

Long non‐coding RNA (lncRNA) plays an essential role in hepatitis B virus‐related hepatocellular carcinoma (HBV‐related HCC) occurrence and development. Single nucleotide polymorphism (SNP) may affect HBV‐related HCC susceptibility by altering the function of lncRNA. However, the relationship between lncRNA SNPs and HBV‐related HCC occurrence and development is still unclear.

Methods

In the present study, based on HBV‐related HCC genome‐wide association studies, eight potentially functional SNPs from two lncRNAs were predicted using a set of bioinformatics strategies. In 643 HBV‐related HCC patients, 549 CHB carriers, and 553 HBV natural clearance subjects from Southern Chinese, we evaluated associations between SNPs and HBV‐related HCC occurrence or development with odds ratio (OR) and 95% confidence interval (CI) under credible genetic models.

Results

In HBV‐related HCC patients, rs9908998 was found to significantly increase the risk of lymphatic metastasis under recessive model (Adjusted OR = 1.95, 95% CI = 1.20–3.17). Lnc‐RP11‐150O12.3 rs2275959, rs1008547, and rs11776545 with cancer family history may show significant multiplicative and additive interactions on HBV‐related HCC susceptibility (all p_Adjusted < .05). The associations of rs2275959, rs1008547, and rs11776545 with distant metastasis of HBV‐related HCC patients were observed in additive model (Adjusted OR = 1.45, 95% CI = 1.06–1.97 for rs2275959; Adjusted OR = 1.45, 95% CI = 1.06–1.98 for rs1008547; Adjusted OR = 1.40, 95% CI = 1.03–1.91 for rs11776545).

Conclusion

Taken together, lnc‐ACACA‐1 rs9908998, lnc‐RP11‐150O12.3 rs2275959, rs1008547, and rs11776545 might be predictors for HBV‐related HCC risk or prognosis.

8p deletions in renal cell carcinoma are associated with unfavorable tumor features and poor overall survival

BACKGROUND AND METHODS

8p deletions are common in renal cell carcinoma. To study their prognostic impact and association with kidney cancer phenotype, a tissue microarray with 1,809 cancers was analyzed by fluorescence in situ hybridization for 8p21 copy numbers.

RESULTS

One thousand four hundred and seventy four interpretable tumors showed substantial differences between renal cancer subtypes. That 8p deletion was only seen in 1 (0.5%) of 216 papillary carcinomas underscores the biologic uniqueness of papillary kidney cancer, which is also defined by a highly distinct morphology. 8p deletions were found in 13.2% of 976 clear cell carcinomas, 7.8% of 77 chromophobe carcinomas, 0.8% of 119 oncocytomas, but also in several rare tumor entities including 1 of 4 collecting duct cancers, 1 of 3 multilocular cystic clear cell renal cell neoplasm of low malignancy, 2 of 10 Xp11.2 translocation cancers, 3 of 18 not otherwise specified carcinomas, and 1 analyzed medullary carcinoma. In clear cell carcinomas, 8p deletions were significantly associated with higher International Society of Urologic Pathologists (ISUP) grading (P = 0.0014), Fuhrman (P = 0.0003) and Thoenes grade (P = 0.0033), advanced tumor stage (P = 0.0002), large tumor diameter (P = 0.0019), distant metastases (P = 0.0183), overall survival (P = 0.0394), and recurrence free survival (P < 0.0001). In multivariate analysis, the prognostic role of 8p deletions was not independent of established clinic-pathological parameters. In conclusion, 8p deletions are strongly linked to tumor aggressiveness in clear cell kidney cancer.

CONCLUSIONS

Because 8p deletions are easy to measure by fluorescence in situ hybridization, 8p deletion assessment, most likely in combination with other parameters, may have a role in future prognosis assessment in clear cell kidney cancer.

MTUS1, a gene encoding angiotensin-II type 2 (AT2) receptor-interacting proteins, in health and disease, with special emphasis on its role in carcinogenesis

Loss of tumor suppressor activity is a frequent event in the formation and progression of tumors and has been listed as an important hallmark of cancers. Microtubule-Associated Scaffold Protein 1 (MTUS1) is a candidate tumor suppressor gene which is reported to be frequently down-regulated in a variety of human cancers including pancreas, colon, bladder, head-and-neck, ovarian, breast cancers, gastric, lung cancers. It is also reported to be implicated in several types of pathologies such as cardiac hypertrophy, atherosclerosis, and SLE-like lymphoproliferative diseases. Moreover, MTUS1-encoded proteins are shown to be involved in the regulation of vital cellular processes such as proliferation, differentiation, DNA repair, inflammation, vascular remodeling and senescence. However, the current knowledge is very limited about the role of this gene in human cancers as well as other type diseases. Besides, there is no literature report which summarizes and criticizes the importance of MTUS1 in the cellular processes, especially in the processes of carcinogenesis. Accordingly, in this comprehensive review, we tried to shed light on the role of tumor suppressor MTUS1/ATIP in health and disease, putting special emphasis on its role in the development and progression of human cancers as well as associated molecular mechanisms and the reasons behind MTUS1/ATIP deficiency, which have been not well documented previously.

MTUS1 and its targeting miRNAs in colorectal carcinoma: significant associations

Deregulated microRNA (miRNA) expression has been shown to be involved in the pathogenesis of several types of cancers including colorectal cancer (CRC). Thus, determining miRNA targets of genes that play critical role in the malignant transformation is very important. Here, expression levels of tumor suppressor microtubule-associated tumor suppressor 1 (MTUS1) and its regulatory miRNAs were reported. Predicted and validated targets of MTUS1 gene was determined by a computational approach. Expressions of MTUS1 and miRNAs were determined by using 96.96 Dynamic Array™ integrated fluidic circuit (Fluidigm). As a result, MTUS1 levels were found to be diminished in formalin-fixed, paraffin-embedded (FFPE) tissue samples of CRC patients compared to controls. Also, several of MTUS1 targeting miRNAs were found to be upregulated in CRC samples (miR-373-3p, 183-5p, 142-5p, 200c-3p, 19a-3p, -20a-5p, -181a-5p, -184, -181d-5p, -372-3p, 27b-3p, 98-5p, -let-7i-5p, -let-7d-5p, -let-7g-5p, -let-7b-5p, and -let-7c-5p). Of these miRNAs, miR-135b-5p, -373-3p, 183-5p, 142-5p, 200c-3p, 19a-3p showed marked expression levels. In contrast, expression levels of let-7a-5p, 7e-5p, 7f-5p, hsa-miR-125a-5p, and 125b-5p were found to be downregulated in CRC tissues. Accordingly, some of the overexpressed miRNAs especially the miR-135b-5p, -373-3p, 183-5p, 142-5p, 200c-3p, and 19a-3p may play key roles in CRC pathophysiology through MTUS1. In contrast, let-7a-5p, 7e-5p, 7f-5p, miR-125a-5p, and 125b-5p may play important roles in CRC carcinogenesis independent from the MTUS1. In conclusion, MTUS1 targeting miRNAs may play key roles in the development of CRC by downregulating tumor suppressor MTUS1.

Genomic losses at 5q13.2 and 8p23.1 in dysplastic hepatocytes are common events in hepatitis B virus-related hepatocellular carcinoma

Chromosomal loci with genomic imbalances are frequently identified in hepatocellular carcinoma (HCC). Greater than two-thirds of hepatitis B virus (HBV)-related HCCs originate from liver cirrhosis following a duration of up to two decades. However, it is unclear whether these genomic imbalances occur and accumulate in dysplastic hepatocytes of the cirrhotic liver during the progression from regenerated nodules to preneoplastic lesions, including dysplastic nodules (DN). In the present study, high-grade DNs (HGDNs) of HBV-related liver cirrhosis were screened to identify loci with genomic imbalances, and the frequency of the identified loci in a group of HCCs was analyzed in order to determine whether there may be a genetic link between liver cirrhosis and HCC. Genomic DNA was extracted from six HGDNs of two cases of HBV-related liver cirrhosis and subjected to array comparative genomic hybridization (CGH) analysis with a NimbleGen 720K microarray. Loci with the most frequently observed genomic imbalances in DNs were further analyzed in 83 cases of HCC by differential polymerase chain reaction (PCR) and quantitative PCR. The array CGH analysis revealed that the majority of genomic imbalances in the HGDNs were genomic losses of small segments, with loss of heterozygosity (LOH) at 5q13.2 and 8p23.1 identified most frequently. Of the 83 HCC cases, 30 (36.1%) cases were identified with LOH at 5q13.2, where known tumor-associated genes are located, including general transcription factor IIH subunit 2 (GTF2H2), baculoviral IAP repeat-containing protein 1 (BIRC1) and occludin (OCLN). LOH frequency at 8p23.1 in HCC was 61.29% (D8S1130) and 68.4% (D8S503) respectively, similar to the results obtained in previous studies. In conclusion, the results of the present study provided evidence that genomic losses at 5q13.2 and 8p23.1 identified in dysplastic hepatocytes of the cirrhotic liver are common events in HCC. HCC-associated chromosomal abnormalities may occur and accumulate in preneoplastic lesions of liver cirrhosis.

The overexpression of MCPH1 inhibits cell growth through regulating cell cycle-related proteins and activating cytochrome c-caspase 3 signaling in cervical cancer

MCPH1, initially identified as an hTERT repressor, has recently been implicated in mediating DNA damage response and maintaining chromosome integrity. This study is to investigate its potential role in the onset of cervical cancer. In the study, decreased expression of MCPH1 was observed in 19 of 31 cases (61.3%) at mRNA level and 44 of 63 cases (69.8%) at protein level of cervical tumor tissues compared with the paired nontumor tissues. Reduced MCPH1 protein expression was significantly associated with high-tumor grade (1 vs. 3 P = 0.013; 2 vs. 3 P = 0.047). In addition to inhibit SiHa cell migration and invasion, the overexpression of MCPH1 inhibited cervical cancer cells growth through inducing S phase arrest and mitochondrial apoptosis. Further analysis demonstrated cyclinA2/CDK2, CDC25C-cyclinB/CDC2, and p53/p21 pathways were involved in the MCPH1 overexpression-induced S phase arrest. Moreover, the overexpression of MCPH1 activated mitochondrial apoptosis through regulating several apoptosis-related proteins such as p53, Bcl-2, Bax, cytochrome c, caspase-3, and PARP-1. Our findings indicate that downregulated MCPH1 correlates with tumor progression in cervical cancer, and MCPH1 has an important role in regulating cell growth through regulating the cell cycle and apoptosis. Thus, it may be a crucial tumor suppressor gene and a novel candidate therapeutic target for cervical cancer.

BRIT1 regulates p53 stability and functions as a tumor suppressor in breast cancer

In humans, the gene encoding the BRCA1 C terminus-repeat inhibitor of human telomerase expression 1 (BRIT1) protein is located on chromosome 8p23.1, a region implicated in the development of several malignancies, including breast cancer. Previous studies by our group and others suggested that BRIT1 might function as a novel tumor suppressor. Thus, identifying the molecular mechanisms that underlie BRIT1's tumor suppressive function is important to understand cancer etiology and to identify effective therapeutic strategies for BRIT1-deficient tumors. We thus investigated the role of BRIT1 as a tumor suppressor in breast cancer by using genetic approaches. We discovered that BRIT1 functions as a post-transcriptional regulator of p53 expression. BRIT1 regulates p53 protein stability through blocking murine double minute 2-mediated p53 ubiquitination. To fully demonstrate the role of BRIT1 as a tumor suppressor, we depleted BRIT1 in normal breast epithelial cells. We found that knockdown of BRIT1 caused the oncogenic transformation of normal mammary epithelial cells. Furthermore, ectopic expression of BRIT1 effectively suppressed breast cancer cell proliferation and colony formation in vitro and tumor growth in vivo. Taken together, our study provides new insights into the biological functions of BRIT1 as a tumor suppressor in human breast cancer.

Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: potential prospects for combined targeted therapeutics (review)

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, and its incidence is increasing worldwide in an alarming manner. The development of curative therapy for advanced and metastatic HCC is a high clinical priority. The HCC genome is complex and heterogeneous; therefore, the identification of recurrent genomic and related gene alterations is critical for developing clinical applications for diagnosis, prognosis and targeted therapy of the disease. This article focuses on recent research progress and our contribution in identifying and deciphering the role of defined genetic alterations in the pathogenesis of HCC. A significant number of genes that promote or suppress HCC cell growth have been identified at the sites of genomic reorganization. Notwithstanding the accumulation of multiple genetic alterations, highly recurrent changes on a single chromosome can alter the expression of oncogenes and tumor suppressor genes (TSGs) whose deregulation may be sufficient to drive the progression of normal hepatocytes to malignancy. A distinct and highly recurrent pattern of genomic imbalances in HCC includes the loss of DNA copy number (associated with loss of heterozygosity) of TSG-containing chromosome 8p and gain of DNA copy number or regional amplification of protooncogenes on chromosome 8q. Even though 8p is relatively small, it carries an unusually large number of TSGs, while, on the other side, several oncogenes are dispersed along 8q. Compelling evidence demonstrates that DLC1, a potent TSG on 8p, and MYC oncogene on 8q play a critical role in the pathogenesis of human HCC. Direct evidence for their role in the genesis of HCC has been obtained in a mosaic mouse model. Knockdown of DLC1 helps MYC in the induction of hepatoblast transformation in vitro, and in the development of HCC in vivo. Therapeutic interventions, which would simultaneously target signaling pathways governing both DLC1 and MYC functions in hepatocarcinogenesis, could result in progress in the treatment of liver cancer.

Interventional therapies for hepatocellular carcinoma

Hepatocellular carcinoma is the third most common cause of cancer-related death. In the past few years, staging systems have been developed that enable patients to be stratified into treatment algorithms in a multidisciplinary setting. Several of these treatments involve minimally invasive image-guided therapy that can be performed by radiologists.

Genome-wide association study of hepatocellular carcinoma in Southern Chinese patients with chronic hepatitis B virus infection

One of the most relevant risk factors for hepatocellular carcinoma (HCC) development is chronic hepatitis B virus (HBV) infection, but only a fraction of chronic HBV carriers develop HCC, indicating that complex interactions among viral, environmental and genetic factors lead to HCC in HBV-infected patients. So far, host genetic factors have incompletely been characterized. Therefore, we performed a genome-wide association (GWA) study in a Southern Chinese cohort consisting of 95 HBV-infected HCC patients (cases) and 97 HBV-infected patients without HCC (controls) using the Illumina Human610-Quad BeadChips. The top single nucleotide polymorphisms (SNPs) were then validated in an independent cohort of 500 cases and 728 controls. 4 SNPs (rs12682266, rs7821974, rs2275959, rs1573266) at chromosome 8p12 showed consistent association in both the GWA and replication phases (OR(combined) = 1.31-1.39; p(combined) = 2.71 × 10(-5)-5.19 × 10(-4); PAR(combined) = 26-31%). We found a 2.3-kb expressed sequence tag (EST) in the region using in-silico data mining and verified the existence of the full-length EST experimentally. The expression level of the EST was significantly reduced in human HCC tumors in comparison to the corresponding non-tumorous liver tissues (P<0.001). Results from sequence analysis and in-vitro protein translation study suggest that the transcript might function as a long non-coding RNA. In summary, our study suggests that variations at chromosome 8p12 may promote HCC in patients with HBV. Further functional studies of this region may help understand HBV-associated hepatocarcinogenesis.

DOK2 as a marker of poor prognosis of patients with gastric adenocarcinoma after curative resection

BACKGROUND

DOK2 is known as the substrate of chmeric p210bcr/abl oncoprotein characterizing chronic myelogenous leukemia with Philadelphia chromosome. Reduced DOK2 expression was recently reported in lung adenocarcinoma, suggesting that this protein acts as a tumor suppressor in solid tumors. The purpose of this study was to determine the significance of DOK2 in gastric cancer.

METHODS

The study subjects were 118 patients who underwent curative surgery for gastric cancer, as well as 7 gastric cancer cell lines. The tissues and cell lines were analyzed for DOK2 gene and protein expressions by histopathology and immunohistochemistry, and also using a microsatellite marker for loss of heterozygosity. Correlation of survival with clinicopathological parameters was investigated by univariate and multivariate analyses.

RESULTS

DOK2 expression was confirmed in the normal gastric mucosa. Considerable differences in the gene expression were noted among the gastric cell lines. Positive DOK2 expression was noted in the noncancerous regions of all pathological specimens, whereas 59 (50.0%) specimens of 118 patients were negatively stained in the tumor. Loss of heterozygosity was observed in 54.5% of DOK2(-) cases. DOK2(-) patients were more likely to develop recurrence than DOK2(+) and showed poorer 5-year overall survival (59.1%) than DOK2(+) (76.4%, P = .0403). Multivariate analysis identified pT (hazard ratio [HR] = 2.748, 95% confidence interval [95% CI] = 1.061-8.927, P = .0361), pN (HR = 2.486, 95% CI = 1.264-4.932, P = .0086), and DOK2(-) (HR = 2.343, 95% CI = 1.211-4.727, P = .0112) as significant and independent determinants of poor survival.

CONCLUSIONS

Our data suggest the potential usefulness of DOK2 as a marker of poor prognosis in patients with gastric cancer after curative resection.

LOH analysis of genes around D4S2964 identifies ARD1B as a prognostic predictor of hepatocellular carcinoma

AIM

To investigate genes around the locus D4S2964 affected by loss of heterozygosity (LOH) and their clinical implications.

METHODS

Four hundred and forty single nucleotide polymorphisms (SNPs) located at 49 genes around D4S2964 were selected from the National Center for Biotechnology Information website for the SNPs microarray fabrication. LOH of SNPs markers in 112 cases of hepatocellular carcinoma (HCC) tissues and paired adjacent liver tissues were investigated by the SNPs microarray. The correlation between allelic losses with clinicopathological features and overall survival was analyzed.

RESULTS

A fine map of LOH of SNPs in genes around D4S2964 was plotted. The average frequency of LOH in genes was 0.39. A correlation between cirrhosis and the FAL index (fractional allelic loss) was found (P = 0.0202). Larger tumor size was found to be significantly associated with LOH in genes ADP-ribosyltransferase 3 (ART3), nucleoporin 54 kDa (NUP54), scavenger receptor class B, member 2 (SCARB2) and coiled-coil domain containing 158 (CCDC158) (P = 0.043, P = 0.019, P = 0.001, P = 0.037, respectively). Kaplan-Meier analysis showed that patients with LOH in ARD1 homolog B (ARD1B) and septin 11 (SEPT11) had a significantly lower survival rate than those with retention (P = 0.021 and P = 0.004, respectively). A Cox regression model suggested that LOH in ARD1B and SEPT11, respectively, were predictors of the overall survival in HCC (P = 0.006 and P = 0.026, respectively).

CONCLUSION

LOH in genes around D4S2964 may play an important role in HCC development and progression. LOH in ARD1B and SEPT11 could serve as novel prognostic predictors in HCC patients.

Gain of miR-151 on chromosome 8q24.3 facilitates tumour cell migration and spreading through downregulating RhoGDIA

Recurrent chromosomal aberrations are often observed in hepatocellular carcinoma (HCC), but little is known about the functional non-coding sequences, particularly microRNAs (miRNAs), at the chromosomal breakpoints in HCC. Here we show that 22 miRNAs are often amplified or deleted in HCC. MicroRNA-151 (miR-151), a frequently amplified miRNA on 8q24.3, is correlated with intrahepatic metastasis of HCC. We further show that miR-151, which is often expressed together with its host gene FAK, encoding focal adhesion kinase, significantly increases HCC cell migration and invasion in vitro and in vivo, mainly through miR-151-5p, but not through miR-151-3p. Moreover, miR-151 exerts this function by directly targeting RhoGDIA, a putative metastasis suppressor in HCC, thus leading to the activation of Rac1, Cdc42 and Rho GTPases. In addition, miR-151 can function synergistically with FAK to enhance HCC cell motility and spreading. Thus, our findings indicate that chromosome gain of miR-151 is a crucial stimulus for tumour invasion and metastasis of HCC.

Genetic and epigenetic silencing of SCARA5 may contribute to human hepatocellular carcinoma by activating FAK signaling

The epigenetic silencing of tumor suppressor genes is a crucial event during carcinogenesis and metastasis. Here, in a human genome-wide survey, we identified scavenger receptor class A, member 5 (SCARA5) as a candidate tumor suppressor gene located on chromosome 8p. We found that SCARA5 expression was frequently downregulated as a result of promoter hypermethylation and allelic imbalance and was associated with vascular invasion in human hepatocellular carcinoma (HCC). Furthermore, SCARA5 knockdown via RNAi markedly enhanced HCC cell growth in vitro, colony formation in soft agar, and invasiveness, tumorigenicity, and lung metastasis in vivo. By contrast, SCARA5 overexpression suppressed these malignant behaviors. Interestingly, SCARA5 was found to physically associate with focal adhesion kinase (FAK) and inhibit the tyrosine phosphorylation cascade of the FAK-Src-Cas signaling pathway. Conversely, silencing SCARA5 stimulated the signaling pathway via increased phosphorylation of certain tyrosine residues of FAK, Src, and p130Cas; it was also associated with activation of MMP9, a tumor metastasis-associated enzyme. Taken together, these data suggest that the plasma membrane protein SCARA5 can contribute to HCC tumorigenesis and metastasis via activation of the FAK signaling pathway.

Clonality and allelotype analyses of focal nodular hyperplasia compared with hepatocellular adenoma and carcinoma

AIM: To identify clonality and genetic alterations in focal nodular hyperplasia (FNH) and the nodules derived from it.

METHODS: Twelve FNH lesions were examined. Twelve hepatocellular adenomas (HCAs) and 22 hepatocellular carcinomas (HCCs) were used as references. Nodules of different types were identified and isolated from FNH by microdissection. An X-chromosome inactivation assay was employed to describe their clonality status. Loss of heterozygosity (LOH) was detected, using 57 markers, for genetic alterations.

RESULTS: Nodules of altered hepatocytes (NAH), the putative precursors of HCA and HCC, were found in all the FNH lesions. Polyclonality was revealed in 10 FNH lesions from female patients, and LOH was not detected in any of the six FNH lesions examined, the results apparently showing their polyclonal nature. In contrast, monoclonality was demonstrated in all the eight HCAs and in four of the HCCs from females, and allelic imbalances were found in the HCAs (9/9) and HCCs (15/18), with chromosomal arms 11p, 13q and 17p affected in the former, and 6q, 8p, 11p, 16q and 17p affected in the latter lesions in high frequencies (≥ 30%). Monoclonality was revealed in 21 (40%) of the 52 microdissected NAH, but was not found in any of the five ordinary nodules. LOH was found in all of the 13 NAH tested, being highly frequent at six loci on 8p, 11p, 13q and 17p.

CONCLUSION: FNH, as a whole, is polyclonal, but some of the NAH lesions derived from it are already neoplastic and harbor similar allelic imbalances as HCAs.

Frequent epigenetic inactivation of SFRP genes in hepatocellular carcinoma

BACKGROUND

Activation of the Wnt signaling pathway is frequently observed in hepatocellular carcinoma (HCC), though mutation of three of its components, CTNNB1, AXIN1, and AXIN2, is observed substantially less often.

METHODS

We examined the relationship between Wnt signaling and epigenetic alteration of secreted frizzled-related protein (SFRP) genes in HCC.

RESULTS

We frequently detected the active form of beta-catenin and accumulation of nuclear beta-catenin in liver cancer cell lines. We detected methylation of SFRP family genes in liver cancer cell lines (SFRP1, 9/12, 75%; SFRP2, 7/12, 58%; SFRP4, 3/12, 25%; SFRP5, 7/12, 58%) and primary HCCs (SFRP1, 9/19, 47%; SFRP2, 12/19, 63%; SFRP5, 8/19, 42%), though methylation of SFRP4 was not found in primary HCCs. SFRP methylation also was detected in hepatitis B or C virus-associated chronic hepatitis (SFRP1, 6/37, 16%; SFRP2, 14/37, 38%; SFRP5, 5/37, 14%) and liver cirrhosis (SFRP1, 10/28, 36%; SFRP2, 9/28, 32%; SFRP5, 3/28, 11%), suggesting that methylation of these genes is an early event in liver carcinogenesis. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor (TCF/LEF) transcriptional activity in liver cancer cells, while overexpression of a beta-catenin mutant and depletion of SFRP1 using siRNA synergistically upregulated TCF/LEF transcriptional activity.

CONCLUSIONS

Our results confirm the frequent methylation and silencing of Wnt antagonist genes in HCC, and suggest that their loss of function contributes to activation of Wnt signaling during hepatocarcinogenesis.

Loss of heterozygosity at D8S298 is a predictor for long-term survival of patients with tumor-node-metastasis stage I of hepatocellular carcinoma

PURPOSE

Our previous studies have shown that chromosome 8p deletion correlates with metastasis of hepatocellular carcinoma (HCC). This study was to determine whether 8p deletion could be used in predicting the prognosis of patients with HCC, particularly in those with early stage of HCC.

EXPERIMENTAL DESIGN

A total of 131 patients with tumor-node-metastasis (TNM) stage I of HCC who underwent curative liver resection were enrolled. Loss of heterozygosity (LOH) was examined using 10 microsatellite markers at chromosome 8p, as well as 14 microsatellites at chromosome 1p, 17p, 4q, 13q, and 16q, and their association with 5-year overall survival (OS) and disease-free survival (DFS) of patients was analyzed.

RESULTS

In the entire cohort of patients, the mean LOH frequency at these 24 loci was 43.2%; LOH frequencies at D8S298 and D1S199 were 31.5% and 33.7%, respectively. LOH at D8S298 was associated with a worse 5-year OS (P = 0.008) and DFS (P = 0.038) in patients with TNM stage I of HCC. Likewise, the patients with LOH at D1S199 had a worse 5-year OS (P < 0.001) and DFS (P = 0.014) compared with those without LOH at D1S199. In multivariate analyses, LOH at D8S298 was an independent predictor of decreased DFS (hazard ratio, 0.372; 95% 95% confidence interval, 0.146-0.948; P = 0.038), whereas LOH at D1S199 was an independent predictor of decreased OS (hazard ratio, 0.281; 95% confidence interval, 0.123-0.643; P = 0.003).

CONCLUSIONS

LOH at D8S298 and D1S199 is independently associated with a worse survival in patients with TNM stage I of HCC after curative resection and could serve as novel prognostic predictors for this subgroup of patients.

Molecular pathogenesis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. Hepatocarcinogenesis is a multistep process evolving from normal through chronic hepatitis/cirrhosis and dysplastic nodules to HCC. With advances in molecular methods, there is a growing understanding of the molecular mechanisms in hepatocarcinogenesis. Hepatocarcinogenesis is strongly linked to increases in allelic losses, chromosomal changes, gene mutations, epigenetic alterations and alterations in molecular cellular pathways. Some of these alterations are accompanied by a stepwise increase in the different pathological disease stages in hepatocarcinogenesis. Overall, a detailed understanding of the underlying molecular mechanisms involved in the progression of HCC is of fundamental importance to the development of effective prevention and treatment regimes for HCC.

Identification of minimal regions of deletion at 8p23.1-22 associated with metastasis of hepatocellular carcinoma

AIMS/BACKGROUND

Loss of heterozygosity (LOH) at 8p is the most frequent chromosomal alteration in tumorigenesis of human cancers. However, the genetic change in metastasis of hepatocellular carcinoma (HCC) still has to be investigated.

METHODS

We used 16 microsatellite markers informative in Japanese patients, selected from among 61 published microsatellite markers at 8p23.2-21 to compare the frequency of LOH in primary tumours (Tps) and metastatic tumours (Tms) in a PCR-based analysis. Sixty-three informative cancerous lesions (26 were Tps, 37 were Tms) from 23 cases of HCC were used.

RESULTS

The frequency of LOH at 8p23.2-21 with at least one marker was 19% in Tps and 68% in Tms. Allelic loss at 8p23.2-21 was significantly more frequent in Tms than in Tps (P=0.0003). More specifically, the frequency of LOH at D8S262, D8S1819, D8S503, D8S1130, D8S552, D8S1109, and D8S261 in Tms was 36-60% respectively.

CONCLUSIONS

In contrast, allelic loss at the same markers in Tp was only detected in 0-17% of the tumour respectively. The significant difference in the frequency of LOH at 8p between primary cancer and metastatic cancer in individual cases of HCC suggests LOH at 8p to be involved in the enhancement of tumour aggressiveness, especially during metastasis.

Concurrent loss of heterozygosity and copy number analysis in adenoid cystic carcinoma by SNP genotyping arrays

Adenoid cystic carcinoma (ACC) is one of the most common malignancies to arise in the salivary glands, yet very little is known of the genetic alterations that are involved in the pathogenesis of this disease. To further examine the genetic changes that underlie ACC, we analyzed genomic DNA obtained from 22 primary ACC and two ACC-derived cell lines by high-density oligonucleotide single-nucleotide polymorphism genotyping arrays (Affymetrix GeneChip Human Mapping 100K Set). Allelotype calls were analyzed by the Haplotype Correction version of the Linkage Disequilibrium Hidden Markov Model to determine loss of heterozygosity using information derived only from tumor samples. Comparison of data obtained from matched tumor-normal samples suggested that only deletion calls of >3 Mb were reliable. Within these parameters, ACC samples revealed a mean of three deletions per tumor, and no consensus areas of deletion were observed across the majority of tumors. Similarly, copy number analysis of primary hybridization data revealed no consensus areas of gene amplification. This is in contrast to a much higher rate of genomic alterations detected in a cohort of squamous carcinomas analyzed by the same methods. Our data show that most ACC have predominantly stable genomes, which is consistent with the theory that telomere crisis does not play a significant role in early stages of ACC tumor progression. Our data suggest that gene mutation and/or epigenetic events that cannot be detected by assay of gross alteration of chromosomal structure are likely to underlie the malignant transformation events of this tumor type.

Frequent loss of heterozygosity in two distinct regions, 8p23.1 and 8p22, in hepatocellular carcinoma

AIM: To identify the precise location of putative tumor suppressor genes (TSGs) on the short arm of chromosome 8 in patients with hepatocellular carcinoma (HCC).

METHODS: We used 16 microsatellite markers informative in Japanese patients, which were selected from 61 published markers, on 8p, to analyze the frequency of loss of heterozygosity (LOH) in each region in 33 cases (56 lesions) of HCC.

RESULTS: The frequency of LOH at 8p23.2-21 with at least one marker was 63% (20/32) in the informative cases. More specifically, the frequency of LOH at 8p23.2, 8p23.1, 8p22, and 8p21 was 6%, 52%, 47%, and 13% in HCC cases. The LOH was significantly more frequent at 8p23.1 and 8p22 than the average (52% vs 22%, P = 0.0008; and 47% vs 22%, P = 0.004, respectively) or others sites, such as 8p23.2 (52% vs 6%, P = 0.003; 47% vs 22%, P = 0.004) and 8p21 (52% vs 13%, P = 0.001; 47% vs 13%, P = 0.005) in liver cancer on the basis of cases. Notably, LOH frequency was significantly higher at D8S277, D8S503, D8S1130, D8S552, D8S254 and D8S258 than at the other sites. However, no allelic loss was detected at any marker on 8p in the lesions of nontumor liver tissues.

CONCLUSION: Deletion of 8p, especially the loss of 8p23.1-22, is an important event in the initiation or promotion of HCC. Our results should be useful in identifying critical genes that might lie at 8p23.1-22.

Promoter methylation of the secreted frizzled-related protein 1 gene SFRP1 is frequent in hepatocellular carcinoma

BACKGROUND

The secreted frizzled-related protein 1 gene (SFRP1) encodes a Wnt/beta-catenin signaling antagonist and frequently is inactivated by promoter methylation in many tumors. However, the role of SFRP1 in hepatocellular carcinoma (HCC) is not clear. Therefore, the authors investigated whether methylation of the SFRP1 promoter is common in HCC and whether it may influence SFRP1 expression.

METHODS

Four HCC cell lines, 54 HCCs, 42 cirrhotic livers, 21 livers with chronic hepatitis, and 15 normal control tissues were analyzed for 1) SFRP1 promoter methylation by using methylation-specific polymerase chain reaction analysis and bisulfite sequencing, 2) SFRP1 messenger RNA expression by using quantitative reverse transcriptase-polymerase chain reaction analysis, and 3) loss of heterozygosity (LOH) by using microsatellite markers flanking the SFRP1 locus. HCC cells were treated with the demethylating agent 5-aza-2'-deoxycytidine to determine whether it could restore SFRP1 expression.

RESULTS

SFRP1 promoter methylation was observed in 75%, 48.2%, 21.4%, 14.3% and 0% in HCC cell lines, primary HCCs, cirrhotic livers, livers with chronic hepatitis, and normal control tissues, respectively. Methylation of the SFRP1 promoter region in HCCs increased significantly compared with control tissues. All samples with SFRP1 methylation showed down-regulation of SFRP1 expression. Demethylation treatment with 5-aza-2'-deoxycytidine in HCC cells restored SFRP1 expression. Moreover, LOH of markers D8S505 and D8S1722 was found in 25% and 27.6% of the informative samples, respectively.

CONCLUSIONS

The current results suggested that promoter hypermethylation of SFRP1 is a common event in HCC and plays an important role in the regulation of SFRP1 expression. In addition to methylation-mediated down-regulation of SFRP1, LOH also may play a role.

BRIT1 regulates early DNA damage response, chromosomal integrity, and cancer

BRIT1, initially identified as an hTERT repressor, has additional functions at DNA damage checkpoints. Here, we demonstrate that BRIT1 formed nuclear foci minutes after irradiation. The foci of BRIT1 colocalized with 53BP1, MDC1, NBS1, ATM, RPA, and ATR. BRIT1 was required for activation of these elements, indicating that BRIT1 is a proximal factor in the DNA damage response pathway. Depletion of BRIT1 increased the accumulation of chromosomal aberrations. In addition, decreased levels of BRIT1 were detected in several types of human cancer, with BRIT1 expression being inversely correlated with genomic instability and metastasis. These results identify BRIT1 as a crucial DNA damage regulator in the ATM/ATR pathways and suggest that it functions as a tumor suppressor gene.

Rho GTPase-activating protein deleted in liver cancer suppresses cell proliferation and invasion in hepatocellular carcinoma

Deleted in liver cancer (DLC1) is a candidate tumor suppressor gene recently isolated from human hepatocellular carcinoma. Structurally, DLC1 protein contains a conserved GTPase-activating protein for Rho family protein (RhoGAP) domain, which has been thought to regulate the activity of Rho family proteins. Previous studies indicated that DLC1 was frequently inactivated in cancer cells. In the present study, we aimed to characterize the tumor suppressor roles of DLC1 in hepatocellular carcinoma. We showed that DLC1 significantly inhibited cell proliferation, anchorage-independent growth, and in vivo tumorigenicity when stably expressed in hepatocellular carcinoma cells. Moreover, DLC1 expression greatly reduced the motility and invasiveness of hepatocellular carcinoma cells. With RhoGAP-deficient DLC1 mutant (DLC1-K714E), we showed that the RhoGAP activity was essential for DLC1-mediated tumor suppressor function. Furthermore, the 292- to 648-amino acid region and the steroidogenic acute regulatory related lipid transfer domain played an auxiliary role to RhoGAP and tumor suppressor function of DLC1. Taken together, our findings showed that DLC1 functions as a tumor suppressor in hepatocellular carcinoma and provide the first evidence to support the hypothesis that DLC1 suppresses cancer cell growth by negatively regulating the activity of Rho proteins.

Clinicopathological significance of loss of heterozygosity and microsatellite instability in hepatocellular carcinoma in China

AIM: To determine the features of microsatellite alterations and their association with clinicopathological characteristics of hepatocellular carcinoma (HCC).

METHODS: Loss of heterozygosity (LOH) and microsatellite instability (MSI) of 55 microsatellite loci were detected with PCR-based microsatellite polymorphism analyses in tumors and corresponding noncancerous liver tissues of 56 surgically resected HCCs using the MegaBACE 500 automatic DNA analysis system.

RESULTS: LOH was found in 44 of 56 HCCs (78.6%) at one or several loci. Frequencies of LOH on 1p, 4q, 8p, 16q, and 17p were 69.6% (39/56), 71.4% (40/56), 66.1% (37/56), 66.1% (37/56), and 64.3% (36/56), respectively. MSI was found in 18 of 56 HCCs (32.1%) at one or several loci. Ten of fifty-six (17.9%) HCCs had MSI-H. Serum HBV infection, alpha-fetoprotein concentration, tumor size, cirrhosis, histological grade, tumor capsule, as well as tumor intrahepatic metastasis, might be correlated with LOH on certain chromosome regions.

CONCLUSION: Frequent microsatellite alterations exist in HCC. LOH, which represents a tumor suppressor gene pathway, plays a more important role in hepatocarcin-ogenesis. MSI, which represents a mismatch repair gene pathway, is a rare event during liver carcinogenesis. Furthermore, LOH on certain chromosome regions may be correlated with clinicopathological characteristics in HCC.

Distinct chromosomal bias of gene expression signatures in the progression of hepatocellular carcinoma

To identify the chromosomal aberrations associated with the progression of liver cancer, we applied expression imbalance map analysis to gene expression data from 31 hepatocellular carcinomas and 19 noncancerous tissues. Expression imbalance map analysis, which detects mRNA expression imbalance correlated with chromosomal regions, showed that expression gains of 1q21-23 (74%), 8q13-21 (48%), 12q23-24 (41%), 17q12-21(48%), 17q25 (25%), and 20q11 (22%) and losses of 4q13 (48%), 8p12-21 (32%), 13q14 (32%), and 17p13 (29%) were significantly associated with hepatocellular carcinoma. Most regions with altered expression identified by expression imbalance map were also identified in previous reports using comparative genomic hybridization. We demonstrated chromosomal copy number gain in 1q21-23 and loss in 17p13 by genomic quantitative PCR, suggesting that gene expression profiles reflect chromosomal alterations. Furthermore, expression imbalance map analysis revealed that more poorly differentiated hepatocellular carcinoma contain more chromosomal alterations, which are accumulated in a stepwise manner in the course of hepatocellular carcinoma progression: expression imbalance of 1q, 8p, 8q, and 17p occur as early events in hepatocarcinogenesis, and 12q, 17q25 and 20q occur as later events. In particular, expression gain of 17q12-21 and loss of 4q were seen to accumulate constantly through the dedifferentiation process. Our data suggest that gene expression profiles are subject to chromosomal bias and that expression imbalance map can correlate gene expression to gene loci with high resolution and sensitivity.

Genomic instability in hepatocellular carcinoma revealed by using the random amplified polymorphic DNA method

PURPOSE

To investigate the genomic instability and their association with clinicopathological characteristics in hepatocellular carcinoma (HCC).

METHODS

DNA isolated from tumors and corresponding non-cancerous liver tissues of 56 patients with HCC was amplified with ten random 10-mer arbitrary primers by the random amplified polymorphic DNA (RAPD) method.

RESULTS

All the cases of HCC were demonstrated to have genomic instability by at least one primer. The incidence of genomic instability ranged from 20 to 70% in each case, and 17.9-50% in each primer. Serum AFP concentration, HBV infection, tumor size, histological grade, tumor capsule invasion, as well as intrahepatic metastasis were associated with the genomic instability on certain primers.

CONCLUSIONS

Genomic instability is a frequent event in HCC. The RAPD is an effective method for the identification and analysis of genomic instability in HCC, and it may provide new information for further evaluating the molecular mechanism of hepatocarcinogenesis.

LFIRE-1/HFREP-1, a liver-specific gene, is frequently downregulated and has growth suppressor activity in hepatocellular carcinoma

We have previously identified several novel genes, which are differentially expressed among human normal liver and hepatocellular carcinomas (HCCs). The full-length liver fibrinogen-related gene-1 (LFIRE-1) cDNA was cloned from the human normal liver cDNA library. LFIRE-1 is highly homologous to HFREP-1 with discrepancy at 5' untranslated region (UTR) and encodes the same fibrinogen-related protein, which suggest that these two sequences might be alternative splicing forms of the same gene, LFIRE-1/HFREP-1, located at human chromosome 8p22. The LFIRE-1 and HFREP-1 are specifically expressed in normal human liver tissue, but reduced or undetectable in most of HCC specimens at both RNA and protein level. Furthermore, the reduction or nonexpression of LFIRE-1/HFREP-1 is significantly associated with the degree of tumor differentiation. Loss of heterozygosity (LOH) analysis revealed allelic loss of LFIRE-1/HFREP-1 on chromosome 8p22 in 57.1% (24/42) of HCC specimens. We detected three inactivation mutations among 45 cases of HCC specimens examined, two of which lost the remaining allele and the third had a replacement of conserved cysteine residue with glycine residue. Notably, the downregulation of LFIRE-1/HFREP-1 expression is frequently associated with allelic loss. The reduction of LFIRE-1/HFREP-1 expression by antisense approach enhances cancer cell proliferation and colony formation in soft agar. Moreover, restoration of exogenous wild-type LFIRE-1/HFREP-1 expression but not LFIRE-1/HFREP-1 missense mutations in human HCC cells inhibited their anchorage-dependent or -independent growth in vitro, and suppressed their tumorigenicity in nude mice. In conclusion, our data demonstrated that liver-specific gene LFIRE-1/HFREP-1 was frequently downregulated and might possess growth suppressor activity in HCC.

Deletions of chromosome 8p and loss of sFRP1 expression are progression markers of papillary bladder cancer

Many molecular alterations are known to occur in urothelial carcinoma of the bladder, but their significance for tumor progression is poorly understood. Deletions of chromosome 8p are frequently found in several tumor types and are often associated with progressive disease. In all, 99 bladder tumors were screened for deletions at 8p using loss of heterozygosity (LOH) and multicolor fluorescence in situ hybridization FISH analyses. Allelic loss on chromosome 8p in at least one marker was found in 25/99 (25%) tumors. There was a significant correlation of 8p deletions with invasive tumor growth and a highly significant association with papillary growth pattern in patients with invasive disease. cDNA array analyses revealed that secreted Frizzled-related protein 1 (sFRP1), an antagonist of Frizzled receptors and Wnt pathway activation on chromosome 8p12-11.1, is frequently downregulated in bladder cancer. To investigate sFRP1 as a candidate for a putative progression-related gene on 8p, urothelial cell lines and primary urothelial carcinomas were screened for sFRP1 expression using quantitative real-time PCR, Northern blot, immunofluorescence and immunohistochemistry (IHC). Of the investigated bladder cancers, 38% showed loss of sFRP1 expression by quantitative RT-PCR. Evaluation of the protein expression by IHC using tissue microarrays containing 776 bladder cancers revealed loss or strong reduction of sFRP1 expression in 66% of cases. SFRP1 loss was associated with higher tumor stage and grade and shorter overall survival. In addition, loss of sFRP1 was an independent indicator of poor survival in patients with papillary but not with muscle invasive bladder cancer. There were neither mutations in the coding region of sFRP1 nor homozygous deletions at 8p12-11.21. However, promoter methylation was detected using methylation-specific PCR in 29% of cases. In conclusion, we could show a close correlation of chromosome 8p deletions and progression of papillary bladder tumors. The sFRP1 gene on chromosome 8p12-11.1 could be a candidate gene for the predicted, progression-related tumor suppressor gene in bladder cancer and could contribute to urothelial carcinogenesis.

Establishment of cell lines from a primary hepatocellular carcinoma and its metastatis

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world with a very poor prognosis that has been associated with tumor metastasis. The molecular mechanism of HCC metastasis is still unclear. In this study, we established cell lines from a primary tumor (H2-P) and its metastasis (H2-M). G-banding karyotyping, comparative genomic hybridization, and fluorescence in situ hybridization were applied to study these two cell lines and the results demonstrated that they are of the same origin. These cell lines provide a very useful tool to identify genetic alterations associated with HCC metastasis.

Diagnosis of intrahepatic metastasis and multicentric carcinogenesis by microsatellite loss of heterozygosity in patients with multiple and recurrent hepatocellular carcinomas

BACKGROUND/AIMS

The prognosis of hepatocellular carcinoma (HCC) is poor because of frequent intrahepatic metastasis (IM) or multicentric carcinogenesis (MC). We compared the effectiveness of loss of heterozygosity (LOH) analysis in the diagnosis of these two forms with that of histopathological diagnosis.

METHODS

Using LOH analysis of 15 specific DNA microsatellite loci, tumor clonality was assessed in 37 cases.

RESULTS

LOH was observed in 30% of seven solitary tumors. According to these results, the selected threshold to diagnose MC was a difference in the LOH status at more than 30% of the analyzed loci, when comparing two samples in the same liver. In nine multiple HCCs, identical genetic and histopathological diagnoses were found in four (IM: 2, MC: 2). Of 21 recurrent tumors, 19 showed LOH for at least one marker. IM and MC were genetically diagnosed in five and ten patients, respectively. Genetic and histopathological diagnoses were identical in ten of 19 patients (IM: 5. MC: 5). Five genetic MC were histopathologically diagnosed as IM (3) and 'undetermined' (2).

CONCLUSIONS

Genetic diagnosis by LOH analysis may be more strict and specific than histopathological diagnosis in the differential diagnosis of IM and MC.

Identification of a new tumor suppressor gene located at chromosome 8p21.3-22

Transformation of normal cells into malignant tumor cells, a process termed carcinogenesis, depends on progressive acquisition of genetic alterations. These result in activation of protooncogenes or inactivation of tumor suppressor genes responsible for the loss of proliferative control in tumor cells and the failure to undergo cellular differentiation. The aim of our study was the identification of molecular regulators of carcinogenesis by studying gene expression during induction of cellular differentiation and quiescence in a three-dimensional (3D) cell culture model. Here, we report the discovery of a tumor suppressor gene located at chromosome 8p21.3-22 near marker D8S254. It is ubiquitously expressed in normal tissue and transiently up-regulated during initiation of cellular differentiation and quiescence in 3D cell culture. In contrast, mRNA expression was not detectable in tissue from pancreatic tumor and the pancreatic tumor cell line MIA PaCa-2. Recombinant expression in the tumor cell line MIA PaCa-2 inhibited proliferation, as shown by a 30% reduction of BrdU uptake after recombinant expression. Immunocytochemistry and Western blot analysis of subcellular fractions demonstrated a mitochondrial localization for the mature protein. In conclusion, we identified a tumor suppressor gene at chromosome 8p21.3-22, encoding a mitochondrial protein, controlling cellular proliferation.

The abnormalities of chromosome 8 in two hepatocellular carcinoma cell clones with the same genetic background and different metastatic potential

PURPOSE

Two hepatocellular carcinoma (HCC) cell clones named MHCC97-H and MHCC97-L with different metastatic potential have recently been established from the same parent cell line MHCC97 in our institute. The cytogenetic alterations of these two clones were investigated in this study to explore the possible clues to the mechanism involved in HCC metastasis.

METHODS

Their chromosomal aberrations were analyzed with comparative genomic hybridization (CGH), chromosome-specific painting, and two-color fluorescence in situ hybridization (FISH).

RESULTS

The aberrations were found in a total of 17 chromosomes, and six kinds of the aberrations including gains of 1q, 7q, 8q, 20, and the losses of 8p23, 21q were found both in the two cell clones and their parent cell line MHCC97. Using modified CGH, with the DNA of MHCC97-L as control to test the MHCC97-H clone, the loss of 8p23 and the gain of 1q31-32, 8q21.3-22, 13q22, 17q22 were highlighted, and the most significant finding was on chromosome 8. Dual color FISH combining a pericentromeric probe and a BAC probe mapping at 8q23.1 was then performed to verify this result, and the signal ratios of the BAC to centromere were 1.43 in MHCC97-H and 1.45 in MHCC97-L, confirming the over-representations at 8q in both cells. Another interesting finding in the dual-color metaphase FISH was the intrachromosomal translocation of 8q to 8p (looked like an isochromosome 8) and non-reciprocal translocation of part of 8q to 4q, which was further clarified and proved by the FISH with whole chromosome 8 painting probe.

CONCLUSIONS

The high copies amplification on 8q, the formation of isochromosome 8, non-reciprocal translocation of partial 8q to 4q, and loss of 8p occurred at the same time and are the characteristic chromosomal aberrations of the two cell clones. The chromosome 8p, especially 8p23, might harbor some novel genes related to the HCC metastasis.

Microdissection-based allelotyping discriminates de novo tumor from intrahepatic spread in hepatocellular carcinoma

A total of 103 cases of hepatocellular carcinoma (HCC) arising in native livers discovered at the time of transplantation underwent allelic loss analysis. HCC mutational allelotyping targeted 10 genomic loci (1p, 3p, 5q, 7q, 8q, 9p, 10q, 17p, 17q, 18q) using 18 polymorphic microsatellite markers situated in proximity to known tumor suppressor genes associated with human carcinogenesis. Gene analysis was performed on microdissected tissue samples removed from 4-microm thick histologic sections at specific topographic sites selected on the basis of representative cellular characteristics. Microdissection targets included largest tumor nodule at 2 locations as well as up to 3 additional tumor nodules in each case. HCC genotyping characteristics including mutational profile and cumulative fractional allelic loss (FAL) were correlated with clinical and pathologic features. Individual nodules of HCC showed 2 patterns of mutational change: (1) essentially concordant mutational profiles consistent with intrahepatic spread of tumor, or (2) discordant mutational profiles consistent with independent primary cancer formation. In 15 of 56 cases (27%) in which the HCC was in a multinodular, bilobar form (T4), sufficient discordance in the allelic loss profile enabled a more accurate T-stage classification with better prediction of recurrence-free survival. In conclusion, microdissection genotyping of HCC is an effective and objective means to (1) distinguish between de novo HCC tumor formation versus intrahepatic spread of cancer and to (2) improve on current methods for prediction of tumor aggressiveness and recurrence-free survival after liver transplantation.