G. Fassina

Squamous cell carcinoma antigen-immunoglobulin M complexes as novel biomarkers for hepatocellular carcinoma

Early detection of hepatocellular carcinoma (HCC), one of the most common and deadly tumors worldwide, still is difficult due to the lack of adequate biomarkers that show high sensitivity and specificity. The authors recently demonstrated that squamous cell carcinoma antigen (SCCA) variants were overexpressed remarkably in all surgically resected HCCs.

Progressive increase of SCCA-IgM immune complexes in cirrhotic patients is associated with development of hepatocellular carcinoma.

About 3–4% of cirrhotic patients develop primary liver cancer every year. Specific serologic markers have not yet been identified for screening of high risk patients. The serpin squamous cell carcinoma antigen (SCCA) is overexpressed in liver cancer and circulating SCCA‐IgM complexes have been described in patients with hepatocellular carcinoma (HCC). The aim of the present study was to assess the behavior of SCCA‐IgM in relation to HCC development in patients with cirrhosis. A retrospective, longitudinal study was conducted in a cohort of prospectively followed cirrhotic patients. Two groups with similar clinical profile at presentation were studied : group A included 16 patients who developed HCC during a median follow up of 4 years; group B included 17 patients who did not develop HCC during the same time interval. Circulating SCCA‐IgM immune complexes were determined using a recently standardized ELISA assay. At presentation similar levels of SCCA‐IgM complexes [mean ± SD: 267.40 ± 382.25 U/ml vs. 249.10 ± 446.90 U/ml, p = 0.9006] and of alpha‐fetoprotein [AFP; 24.11 ± 59.04 IU/ml vs. 10.91 ± 23.34 IU/ml, p = 0.3995] were detected in group A and in group B. The increase over time (ϕ) of SCCA‐IgM, assessed within at least one year before clinical diagnosis of HCC, was remarkably higher in group A than in group B (mean ± SD = 280.05 ± 606.71 (U/ml)/year vs. −37.92 ± 95.94 (U/ml)/year, p = 0.0408), while AFP increase was not significantly different (11.89 ± 23.27 (IU/ml)/year vs. 3.67 ± 11.46 (IU/ml)/year, p = 0.2179). Receiver operating characteristic (ROC) curves were plotted for the rate of change in the levels of both markers and the diagnostic accuracy measured as AUROC was higher for SCCA‐IgM ϕ (0.821) than for AFP ϕ (0.654). In conclusion, the progressive increase of SCCA‐IgM over time was associated with liver tumor development, suggesting that monitoring the behavior of SCCA‐IgM might become useful to identify cirrhotic patients at higher risk of HCC development.

Monitoring SCCA-IgM complexes in serum predicts liver disease progression in patients with chronic hepatitis.

Summary.  About 30% of the patients with chronic hepatitis develop a progressive liver disease and one of the most intriguing issues is the detection of noninvasive markers for fibrosis stage and disease progression. High levels of squamous cell carcinoma antigen (SCCA)‐immunoglobulin M (IgM) are detectable in hepatocellular carcinoma and their increase in cirrhotic patients can predict tumour development. As SCCA‐IgM can also be detectable at low percentages in patients with chronic hepatitis, the aim of this study was to assess SCCA‐IgM complexes in relation to disease outcome in this group of patients. An ELISA assay was used to determine the presence of SCCA‐IgM in 188 patients with chronic hepatitis and in 100 controls. An additional serum sample was available after a median period of 6 years in 57 untreated patients: these patients were subdivided in group A, including eight patients with a fibrosis score increase ≥2 in a second liver biopsy and group B, including 49 patients without fibrosis progression during a similar follow up. SCCA‐IgM complexes were detectable in 63 of 188 (33%) patients but in none of the controls. A significant increase of SCCA‐IgM levels over time was observed in patients with fibrosis progression (mean ± SD: 117 ± 200 U/mL/year), but not in those without histologic deterioration (mean ± SD: –8.8 ± 31 U/mL/year, P < 0.0001). In conclusion, monitoring SCCA‐IgM levels over time appears a useful approach to identify patients with chronic hepatitis at higher risk for cirrhosis development.

Synthesis and in vitro study of novel neuraminidase inhibitors against avian influenza virus

Evidences of oseltamivir resistant influenza patients raised the need of novel neuraminidase inhibitors. In this study, five oseltamivir analogs PMC-31-PMC-36, synthesised according to the outcomes of a rational design analysis aimed to investigate the effects of substitution at the 5-amino and 4-amido groups of oseltamivir on its antiviral activity, were screened for their inhibition against neuraminidase N1 and N3. The enzymes used as models were from the avian influenza A H7N1 and H7N3 viruses. The neuraminidase inhibition assay was carried out by using recombinant species obtained from a baculovirus expression system and the fluorogenic substrate MUNANA. The assay was validated by using oseltamivir carboxylate as a reference inhibitor. Among the tested compounds, PMC-36 showed the highest inhibition on N1 with an IC(50) of 14.6±3.0nM (oseltamivir 25±4nM), while PMC-35 showed a significant inhibitory effect on N3 with an IC(50) of 0.1±0.03nM (oseltamivir 0.2±0.02nM). The analysis of the inhibitory properties of this panel of compounds allowed a preliminary assessment of a structure-activity relationship for the modification of the 4-amido and 5-amino groups of oseltamivir carboxylate. The substitution of the acetamido group in the oseltamivir structure with a 2-butenylamido moiety reduced the observed activity, while the introduction of a propenylamido group was well tolerated. Substitution of the free 5-amino group of oseltamivir carboxylate with an azide, decreased the activity against both N1 and N3. When these structural changes were both introduced, a dramatic reduction of activity was observed for both N1 and N3. The alkylation of the free 5-amino group in oseltamivir carboxylate introducing an isopropyl group seemed to increase the inhibitory effect for both N1 and N3 neuraminidases, displaying a more pronounced effect against N1.

Experimental validation of specificity of the squamous cell carcinoma antigen-immunoglobulin M (SCCA-IgM) assay in patients with cirrhosis

Abstract Background: Squamous cell carcinoma antigen-immunoglobulin M (SCCA-IgM) is a useful biomarker for the risk of development of hepatocellular carcinoma (HCC) in patients with cirrhosis due to its progressive increase associated to HCC evolution. In patients with cirrhosis, other assays have been affected by interfering reactivities of IgM. In this study, the analytical specificity of the SCCA-IgM assay was assessed by evaluating SCCA-IgM measurement dependence on different capture phases, and by measuring the recovery of SCCA-IgM reactivity following serum fractionation. Methods: Serum samples from 82 patients with cirrhosis were analyzed. SCCA-IgM was measured using the reference test (Hepa-IC, Xeptagen, Italy) that is based on rabbit oligoclonal anti-squamous cell carcinoma antigen (SCCA) and a dedicated ELISA with a mouse monoclonal anti-SCCA as the capture antibody. Results: SCCA-IgM concentrations measured with the reference assay (median value=87 AU/mL) were higher than those measured with the mouse monoclonal test (median value=78 AU/mL). However, the differences in the SCCA-IgM distribution were not statistically significant (p>0.05). When SCCA-IgM concentrations measured with both tests were compared, a linear correlation was found (r=0.77, p<0.05). Fractionation of the most reactive sera by gel-filtration chromatography showed that total recovery of SCCA-IgM reactivity was seen only in the fractions corresponding to components with a molecular weight higher than IgM and SCCA (>2000 kDa) with both tests. Conclusions: The equivalence of both SCCA-IgM assays and the absence of reactivity not related to immune complexes support the analytical specificity of SCCA-IgM measurements. The results validate the assessment of SCCA-IgM for prognostic purposes in patients with cirrhosis. Clin Chem Lab Med 2010;48:217–23.

HCV genotype 3 and squamous cell carcinoma antigen (SCCA)-IgM are independently associated with histological features of NASH in HCV-infected patients.

Nonalcoholic steatohepatitis (NASH) enhances the risk of progressive liver disease. In chronic hepatitis C (CHC), liver steatosis is frequent, especially in genotype 3, but its clinical significance is debated. As squamous cell carcinoma antigen (SCCA)‐IgM has been associated with advanced liver disease and risk of tumour development, we evaluated its occurrence in CHC and the possible relation with NASH at liver biopsy. Using a validated ELISA, serum SCCA‐IgM was measured in 91 patients with CHC at the time of liver biopsy performed before antiviral treatment, at the end of treatment and 6 months thereafter, and in 93 HCV‐negative patients with histological diagnosis of nonalcoholic fatty liver disease, as controls. SCCA‐IgM was detected in 33% of CHC patients and in 4% of controls. This biomarker was found more elevated in CHC patients with histological NASH, and at multivariate analysis, SCCA‐IgM and HCV genotype 3 were independently associated with NASH [OR (95% CI): 6.94 (1.21–40) and 27.02 (4.44–166.6)]. As predictors of NASH, HCV genotype 3 and SCCA‐IgM had a specificity and a sensitivity of 97% and 44%, and of 95% and 27%, respectively. PPV and NPV were 80% and 86% for HCV genotype 3 vs 73% and 72% for SCCA‐IgM. In patients with sustained virologic response to therapy, SCCA‐IgM levels decreased significantly, while these remained unchanged in nonresponders. In conclusion, SCCA‐IgM is detectable in one‐third of patients with CHC and significantly correlates with histological NASH.

Squamous cell carcinoma antigen-1 (SERPINB3) polymorphism in chronic liver disease

BACKGROUND The serpin squamous cell carcinoma antigen (SCCA, SERPINB3) has been found over-expressed in primary liver cancer and at lower extent in cirrhosis and chronic hepatitis. A novel SCCA-1 variant (SCCA-PD), presenting a single mutation in the reactive centre (Gly351Ala), has been recently identified (rs3180227). AIM To explore SCCA-1 polymorphism in patients with HCV infection as single etiologic factor and different extent of liver disease. METHODS One hundred and fourty-eight patients with chronic HCV infection (45 chronic hepatitis, 53 cirrhosis, 50 HCC) and 50 controls were evaluated. SCCA-1 polymorphism was studied by restriction fragment length polymorphism and confirmed randomly by direct sequencing. Circulating SCCA-IgM complex was determined by ELISA. RESULTS SCCA-PD was detected with higher frequency in cirrhotic patients (45.3%, odds ratio=2.62; 95%CI 1.13-6.10, p=0.038) than in patients with chronic hepatitis or in controls (24.4% and 24%, respectively). Intermediate figures were found in hepatocarcinoma (36.0%). SCCA-IgM in serum was lower in patients carrying SCCA-PD than in wild type patients and the difference was statistically significant in cirrhotic patients (mean+/-S.D.=117.45+/-54.45 U/ml vs. 268.52+/-341.27 U/ml, p=0.026). CONCLUSIONS The newly identified SCCA-PD variant was more frequently found in liver cirrhosis, suggesting that patients carrying this polymorphism are more prone to develop progressive liver fibrosis.

Increased antiprotease activity of the SERPINB3 polymorphic variant SCCA-PD

SERPINB3 has been found in chronic liver damage and hepatocellular carcinoma, but not in normal liver. By direct mRNA sequencing, a new SERPINB3 polymorphism (SCCA-PD) has been identified, presenting the substitution Gly351Ala in the reactive center loop of the protein. The prevalence of the SCCA-PD isoform has been found to be significantly higher in patients with cirrhosis than in patients with chronic liver disease and in normal subjects. The aim of this study was to investigate the biological and functional activity of SERPINB3 isoforms using in vitro models. HepG2 and Huh7 cells lines were transfected with plasmid vectors containing wild-type SERPINB3 or its polymorphic variant SCCA-PD and their expression at transcriptional and protein level was determined. To assess the functional activity, both recombinant proteins were produced and kinetic analysis was carried out using papain and cathepsin-L as target proteases. In addition, the inhibition of JNK kinase activity by SERPINB3 isoforms was assessed. The crystal structure of wild-type SERPINB3 at 2.7 Å resolution was used for preparation of refined 3D models of the two isoforms. The results showed that transcriptional activity and protein expression of the two isoforms were similar in both transfected cell lines. Both SERPINB3 preparations exerted a dose-dependent protease inhibitory activity, but the effect of SCCA-PD was higher than that of the wild-type isoform. This result was supported by 3D modelling, where increased hydrophobic profile of the SCCA-PD isoform, introduced by the G351A mutation, was detected. In addition, at high protein concentration, SCCA-PD revealed a 16% higher inhibitory effect on c-Jun phosphorylation by JNK1, compared with wild-type SERPINB3. In conclusion, the single amino acid substitution in the SERPINB3 reactive site loop improves the functional activity of SCCA-PD isoform. This different antiprotease activity might favor disease progression in patients carrying this polymorphism.

The Effects of Combinatorial Chemistry and Technologies on Drug Discovery and Biotechnology – a Mini Review

Abstract The review will focus on the aspects of combinatorial chemistry and technologies that are more relevant in the modern pharmaceutical process. An historical, critical introduction is followed by three chapters, dealing with the use of combinatorial chemistry/high throughput synthesis in medicinal chemistry; the rational design of combinatorial libraries using computer-assisted combinatorial drug design; and the use of combinatorial technologies in biotechnology. The impact of “combinatorial thinking” in drug discovery in general, and in the examples reported in details, is critically discussed. Finally, an expert opinion on current and future trends in combinatorial chemistry and combinatorial technologies is provided.