Kaposi's sarcoma: etiology and pathogenesis, inducing factors, causal associations, and treatments: facts and controversies

Kaposi's sarcoma (KS), an angioproliferative disorder, has a viral etiology and a multifactorial pathogenesis hinged on an immune dysfunction. The disease is multifocal, with a course ranging from indolent, with only skin manifestations to fulminant, with extensive visceral involvement. In the current view, all forms of KS have a common etiology in human herpesvirus (HHV)-8 infection, and the differences among them are due to the involvement of various cofactors. In fact, HHV-8 infection can be considered a necessary but not sufficient condition for the development of KS, because further factors (genetic, immunologic, and environmental) are required. The role of cofactors can be attributed to their ability to interact with HHV-8, to affect the immune system, or to act as vasoactive agents. In this contribution, a survey of the current state of knowledge on many and various factors involved in KS pathogenesis is carried out, in particular by highlighting the facts and controversies about the role of some drugs (quinine analogues and angiotensin-converting enzyme inhibitors) in the onset of the disease. Based on these assessments, it is possible to hypothesize that the role of cofactors in KS pathogenesis can move toward an effect either favoring or inhibiting the onset of the disease, depending on the presence of other agents modulating the pathogenesis itself, such as genetic predisposition, environmental factors, drug intake, or lymph flow disorders. It is possible that the same agents may act as either stimulating or inhibiting cofactors according to the patient’s genetic background and variable interactions.

Treatment guidelines for each form of KS are outlined, because a unique standard therapy for all of them cannot be considered due to KS heterogeneity. In most cases, therapeutic options, both local and systemic, should be tailored to the patient’s peculiar clinical conditions.

Clinical oncology in resource-limited settings

Infectious Agents and Cancer is introducing a new section of Clinical Oncology with the main objective of stimulating debate through articles published in the section. Infectious diseases have been the major causes of morbidity and mortality in human populations, and have dominated the medical approach to clinical and public health. Successful efforts to control mortality from acute infections have paved the way for chronic, mostly indolent, infections to become major causes of morbidity. Cancer, hitherto thought to be rare in resource-limited settings, is becoming a major contributor. The changes in mortality patterns are due, in part, to diseases linked to rapid changes in lifestyle, urbanization, and pollution. These diseases include many of the non-infection associated cancers. However, there is a dearth of information about the burden, pathogenesis, and therapeutic approaches about cancer in resource-limited countries. There are also substantial other challenges, including economic, infrastructure, technology, and personnel. The Journal advocates for interactive local-global (lo-bal) efforts to generate relevant knowledge about cancer burden, pathogenesis, and therapeutic approaches using a bottom-up approach to sharpen the focus on local and global relevance of research and clinical and public practice, particularly in resource-limited countries. The section on Clinical Oncology in Infectious Agents and Cancer will harness these "lo-bal" strategies to reduce substantially the time from concept, discovery, and development and implementation of locally and globally applicable diagnostic and therapeutic technologies.

Challenges in cancer vaccine development for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common liver malignancy, representing the third and fifth leading cause of death from cancer worldwide in men and women, respectively. The main risk factor for the development of HCC is the hepatitis B and C virus (HBV and HCV) infection; non-viral causes (e.g., alcoholism and aflatoxin) are additional risk factors. HCC prognosis is generally poor because of the low effectiveness of available treatments and the overall 5-year survival rate is approximately 5-6%. In this framework, immunotherapeutic interventions, including cancer vaccines, may represent a novel and effective therapeutic tool. However, only few immunotherapy trials for HCC have been conducted so far with contrasting results, suggesting that improvements in several aspects of the immunotherapy approaches need to be implemented. In particular, identification of novel specific tumor antigens and evaluation of most advanced combinatorial strategies could result in unprecedented clinical outcomes with great beneficial effect for HCC patients. The state of the art in immunotherapy strategies for HCC and future perspectives are reported in the present review.

VLPs and particle strategies for cancer vaccines

Effective delivery of tumor antigens to APCs is one of the key steps for eliciting a strong and durable immune response to tumors. Several cancer vaccines have been evaluated in clinical trials, based on soluble peptides, but results have not been fully satisfactory. To improve immunogenicity particles provide a valid strategy to display and/or incorporate epitopes which can be efficiently targeted to APCs for effective induction of adaptive immunity. In the present review, we report some leading technologies for developing particulate vaccines employed in cancer immunotherapy, highlighting the key parameters for a rational design to elicit both humoral and cellular responses.

Characterization of humoral responses to soluble trimeric HIV gp140 from a clade A Ugandan field isolate

Trimeric soluble forms of HIV gp140 envelope glycoproteins represent one of the closest molecular structures compared to native spikes present on intact virus particles. Trimeric soluble gp140 have been generated by several groups and such molecules have been shown to induce antibodies with neutralizing activity against homologous and heterologous viruses. In the present study, we generated a recombinant trimeric soluble gp140, derived from a previously identified Ugandan A-clade HIV field isolate (gp140_94UG018). Antibodies elicited in immunized rabbits show a broad binding pattern to HIV envelopes of different clades. An epitope mapping analysis reveals that, on average, the binding is mostly focused on the C1, C2, V3, V5 and C5 regions. Immune sera show neutralization activity to Tier 1 isolates of different clades, demonstrating cross clade neutralizing activity which needs to be further broadened by possible structural modifications of the clade A gp140_94UG018. Our results provide a rationale for the design and evaluation of immunogens and the clade A gp140_94UG018 shows promising characteristics for potential involvement in an effective HIV vaccine with broad activity.

Infections and cancer: debate about using vaccines as a cancer control tool

In 2012, Infectious Agents and Cancer commissioned a thematic series collection of articles on Prevention of HPV related cancer. The articles have attracted wide interest and stimulated debate, including about the utility of vaccines in cancer control. The application of vaccines to cancer control fulfills a promise envisioned at the turn of the 20^th century when remarkable experiments showed that some cancers were caused by infections. This suggested the possibility of applying infection-control strategies to cancer control. Vaccines represent the most practical cost-effective technology to prevent wide human suffering and death from many acute infectious diseases, such as small pox or polio. Hitherto applied to control of acute fatal infections, vaccines, if developed, might provide a potent way to control cancer. The articles in the HPV thematic series show success in developing and applying a vaccine against human papilloma virus (HPV). A vaccine is also available against hepatitis B virus (HBV), which causes liver cancer. These vaccines augment the tools available to control the associated cancers. Scientific endeavor continues for six other cancer-associated infections, mostly viruses. Not surprisingly, debate about the safety of vaccines targeting cancer has been triggered in the scientific community. Questions about safety have been raised for those populations where other means to control these cancers may be available. Although it is difficult to quantify risk from vaccines in individuals where other cancer control services exist, it is likely to be low. Vaccines are much safer today than before. Technological advancement in vaccine development and manufacture and improved regulatory review and efficient distribution have minimized substantially the risk for harm from vaccines. Formal and informal debate about the pros and cons of applying vaccines as a cancer control tools is ongoing in scientific journals and on the web. Infectious Agents and Cancer encourages evidence-based discussion to clarify understanding of the role of vaccines in cancer control. In a similar vein, the journal will not consider anecdotal reports and rhetorical arguments because they are unlikely to inform policy, regulation, or the public.

Mutations in TP53, CTNNB1 and PIK3CA genes in hepatocellular carcinoma associated with hepatitis B and hepatitis C virus infections

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. Hepatocarcinogenesis is a multistep process mainly associated with persistent infection with hepatitis B (HBV) or C (HCV) viruses and always involving the accumulation of genetic alterations over decades of chronic liver disease. Mutations in TP53 and CTNNB1 genes are considered the cancer drivers for HCC development with variable frequencies depending on the etiology. Here we present a comprehensive review evaluating somatic mutations in TP53 and CTNNB1 genes in HBV- and HCV-related HCCs. Moreover, we report the mutational analysis of TP53 (exons 4-9) and CTNNB1 (exon 3) as well as PIK3CA (exon 9) genes in HCC from Southern Italy. The overall mutation frequency of TP53 and CTNNB1 was 33.3%, while hotspot variations in PIK3CA were completely absent. CTNNB1 mutations were significantly associated with young age (P=0.019) and moderately/poorly differentiated HCV-related HCC (P=0.015). The extended analysis of genetic alterations will help to identify molecular markers for liver cancer prevention, diagnosis and treatment of HBV and HCV-associated liver cancer.

Molecular signatures associated with HCV-induced hepatocellular carcinoma and liver metastasis

Hepatocellular carcinomas (HCCs) are a heterogeneous group of tumors that differ in risk factors and genetic alterations. In Italy, particularly Southern Italy, chronic hepatitis C virus (HCV) infection represents the main cause of HCC. Using high-density oligoarrays, we identified consistent differences in gene-expression between HCC and normal liver tissue. Expression patterns in HCC were also readily distinguishable from those associated with liver metastases. To characterize molecular events relevant to hepatocarcinogenesis and identify biomarkers for early HCC detection, gene expression profiling of 71 liver biopsies from HCV-related primary HCC and corresponding HCV-positive non-HCC hepatic tissue, as well as gastrointestinal liver metastases paired with the apparently normal peri-tumoral liver tissue, were compared to 6 liver biopsies from healthy individuals. Characteristic gene signatures were identified when normal tissue was compared with HCV-related primary HCC, corresponding HCV-positive non-HCC as well as gastrointestinal liver metastases. Pathway analysis classified the cellular and biological functions of the genes differentially expressed as related to regulation of gene expression and post-translational modification in HCV-related primary HCC; cellular Growth and Proliferation, and Cell-To-Cell Signaling and Interaction in HCV-related non HCC samples; Cellular Growth and Proliferation and Cell Cycle in metastasis. Also characteristic gene signatures were identified of HCV-HCC progression for early HCC diagnosis.

CONCLUSIONS

A diagnostic molecular signature complementing conventional pathologic assessment was identified.

Developments in virus-like particle-based vaccines for HIV

Virus-like particles (VLPs) hold great promise for the development of effective and affordable vaccines. VLPs, indeed, are suitable for presentation and efficient delivery to antigen-presenting cells of linear as well as conformational antigens. This will ultimately result in a crosspresentation with both MHC class I and II molecules to prime CD4(+) T-helper and CD8(+) cytotoxic T cells. This review describes an update on the development and use of VLPs as vaccine approaches for HIV.

Somatic mutations of STK11 gene in human papillomavirus positive and negative penile cancer

Background

Human papillomavirus (HPV) infection accounts for about 40-50% of all cases of penile carcinoma suggesting that other factors, including host genetic status, are involved in neoplastic transformation. In this perspective, STK11 gene, which has been found frequently mutated in HPV-related cervical carcinoma, has been analyzed in HPV-positive and HPV-negative invasive penile cancers to establish its mutational status and the possible correlation of HPV infection with specific genetic alterations.

Methods

Genomic DNAs extracted from 26 cases of penile squamous cell carcinoma were analyzed for genetic alterations in the exons 1 to 9 of STK11 gene by quantitative real-time PCR. Ratios of potentially deleted and non-deleted exons were indicative of specific loss of STK11 coding regions. DNA samples of 5 cancer cases were subjected to standard PCR amplification of STK11 exons 1 to 9 and analyzed for somatic mutations by direct nucleotide sequencing analysis.

Results

Heterozygous deletions of STK11 exon 1 and 2 were identified in 2 out of 14 HPV-positive (14.3%) and 1 out of 12 HPV-negative cases (8.3%). Complete nucleotide sequencing analysis of exons 1 to 9 showed a single nucleotide change upstream the exon 2 coding region in 1 out of 5 penile carcinoma samples.

Conclusions

The present results suggest that single nucleotide mutations and/or deletions of STK11 gene are rare events in penile cancer. Moreover, no significant association was observed between STK11 alterations and HPV infection in these tumors.

Identification and sequence analysis of a novel human leukocyte antigen allele B*51:141

The newly detected HLA-B*51:141 is distinguished from HLA-B*51:08 by a single-nucleotide exchange at codon 30 where D is replaced by Y.

Immunogenomics approaches for vaccine evaluation

Vaccines represent a potent tool to prevent or contain diseases with high morbidity or mortality. However, despite their widespread use, there is still a limited understanding of the mechanisms underlying the effective elicitation of protective immune responses by vaccines. The integrated co-operation between cells and molecules of innate and adaptive immune systems is under intense study by several groups and constantly updated. The recent development of new technologies and computational tools permits the comprehensive and quantitative analysis of the interactions between all of the components of immunity over time. This study reviews recent progress in exploiting an immunogenomics approach, within the systems biology strategy, to study and evaluate vaccine strategies for infectious and neoplastic diseases. The final goal of this approach is 2-fold, looking for novel and unpredictable mechanisms as well as identifying common immune signatures, relevant for predicting immune responsiveness to improve the design of vaccine strategies. Such approach, indeed, would enable the switch from 'empirical' to 'knowledge-based' vaccinology, leading to a patient-tailored treatment.

Molecular characterization analysis of the outer protein layer (VP7) from human rotavirus A genotype G1 isolate identified in Iran: implications for vaccine development

The full open reading frame of the outer protein layer VP7 from an isolate of human rotavirus identified in 2010 in an Iranian child admitted to hospital with gastroenteritis was amplified from a clinical stool specimen and subjected to molecular characterization. Genetic and phylogenetic analyses indicated that the analyzed gene falls into the G1 genotype forming a sub-cluster with sequences recently identified in Iran and geographically distant countries. Such results were confirmed by protein sequence alignment, showing a highly conserved "G1-like?? amino acid sequence pattern within the known three main immunodominant regions. These results are extremely relevant in a perspective of vaccine development. Indeed, the present study confirms that the A group G1 genotype is the most prevalent Rotavirus circulating in Iran and supports the development of G1 genotype-based rotavirus vaccine for this country.

Multiparametric analyses of human PBMCs loaded ex vivo with a candidate idiotype vaccine for HCV-related lymphoproliferative disorders

Hepatitis C virus (HCV) has been identified as one of the major risk factors for type II mixed cryoglobulinemia (MC), during the clinical evolution of chronic hepatitis, which may lead to development of B cell non-Hodgkin's lymphoma (NHL). We have previously shown that the candidate idiotype vaccine, based on the IGKV3-20 light chain protein, is able to induce activation and maturation of circulating antigen presenting cells (APCs) in both HCV-positive and HCV-negative healthy control subjects, with production of Th2-type cytokines. Here, the effect of the recombinant IGKV3-20 protein on human peripheral blood mononuclear cells (PBMCs) from HCV-positive subjects, with known blood levels of cryoglobulins, is shown via gene expression profiling analysis combined to multiparameter flow cytometry and multiplex analyses of cytokines.

Advances in viral oncology research: summary of the 3rd International Meeting

The 3rd International Conference on Viral Oncology Research, supported by the Italian Society for Virology, took place in Naples on 4-6 October 2011. The meeting was articulated in five sessions covering all aspects of viral oncology from laboratory science to clinical interventions. The session topics were epidemiology and mechanisms of virus-associated cancers; oncogenic DNA viruses; oncogenic RNA viruses and preventive and therapeutic strategies for virus-associated neoplasia. More than 100 scientists attended the meeting. A summary of the invited lectures and oral selected presentations is reported.

Characterization of the human papillomavirus (HPV) integration sites into genital cancers

Oncogenic HPVs have been found frequently integrated into human genome of invasive cancers and chromosomal localization has been extensively investigated in cervical carcinoma. Few studies have analyzed the HPV integration loci in other genital cancers. We have characterized the integration sites of HPV16 in invasive penile carcinoma by means of Alu-HPV-based PCR. Nucleotide sequence analysis of viral-human DNA junctions showed that HPV integration occurred in one case within the chromosome 8q21.3 region, in which the FAM92A1 gene is mapped, and in the second case inside the chromosome 16p13.3, within the intronic region of TRAP1 gene. These results confirm previous observations, summarized in a systematic review of the literature, on the HPV integration events in gene loci relevant to cancer pathogenesis.

Innate immunity and hepatitis C virus infection: a microarray's view

Hepatitis C virus (HCV) induces a chronic infection in more than two-thirds of HCV infected subjects. The inefficient innate and adaptive immune responses have been shown to play a major pathogenetic role in the development and persistence of HCV chronic infection. Several aspects of the interactions between the virus and the host immune system have been clarified and, in particular, mechanisms have been identified which underlie the ability of HCV to seize and subvert innate as well as adaptive immune responses. The present review summarizes recent findings on the interaction between HCV infection and innate immune response whose final effect is the downstream inefficient development of antigen-specific adaptive immunity, thereby contributing to virus persistence.

Evaluation of a combined triple method to detect causative HPV in oral and oropharyngeal squamous cell carcinomas: p16 Immunohistochemistry, Consensus PCR HPV-DNA, and In Situ Hybridization

BACKGROUND

Recent emerging evidences identify Human Papillomavirus (HPV) related Head and Neck squamous cell carcinomas (HN-SCCs) as a separate subgroup among Head and Neck Cancers with different epidemiology, histopathological characteristics, therapeutic response to chemo-radiation treatment and clinical outcome. However, there is not a worldwide consensus on the methods to be used in clinical practice. The endpoint of this study was to demonstrate the reliability of a triple method which combines evaluation of: 1. p16 protein expression by immunohistochemistry (p16-IHC); 2. HPV-DNA genotyping by consensus HPV-DNA PCR methods (Consensus PCR); and 3 viral integration into the host by in situ hybridization method (ISH). This triple method has been applied to HN-SCC originated from oral cavity (OSCC) and oropharynx (OPSCC), the two anatomical sites in which high risk (HR) HPVs have been clearly implicated as etiologic factors. Methylation-Specific PCR (MSP) was performed to study inactivation of p16-CDKN2a locus by epigenetic events. Reliability of multiple methods was measured by Kappa statistics.

RESULTS

All the HN-SCCs confirmed HPV positive by PCR and/or ISH were also p16 positive by IHC, with the latter showing a very high level of sensitivity as single test (100% in both OSCC and OPSCC) but lower specificity level (74% in OSCC and 93% in OPSCC).Concordance analysis between ISH and Consensus PCR showed a faint agreement in OPSCC (κ = 0.38) and a moderate agreement in OSCC (κ = 0.44). Furthermore, the addition of double positive score (ISHpositive and Consensus PCR positive) increased significantly the specificity of HR-HPV detection on formalin-fixed paraffin embedded (FFPE) samples (100% in OSCC and 78.5% in OPSCC), but reduced the sensitivity (33% in OSCC and 60% in OPSCC). The significant reduction of sensitivity by the double method was compensated by a very high sensitivity of p16-IHC detection in the triple approach.

CONCLUSIONS

Although HR-HPVs detection is of utmost importance in clinical settings for the Head and Neck Cancer patients, there is no consensus on which to consider the 'golden standard' among the numerous detection methods available either as single test or combinations. Until recently, quantitative E6 RNA PCR has been considered the 'golden standard' since it was demonstrated to have very high accuracy level and very high statistical significance associated with prognostic parameters. In contrast, quantitative E6 DNA PCR has proven to have very high level of accuracy but lesser prognostic association with clinical outcome than the HPV E6 oncoprotein RNA PCR. However, although it is theoretically possible to perform quantitative PCR detection methods also on FFPE samples, they reach the maximum of accuracy on fresh frozen tissue. Furthermore, worldwide diagnostic laboratories have not all the same ability to analyze simultaneously both FFPE and fresh tissues with these quantitative molecular detection methods. Therefore, in the current clinical practice a p16-IHC test is considered as sufficient for HPV diagnostic in accordance with the recently published Head and Neck Cancer international guidelines. Although p16-IHC may serve as a good prognostic indicator, our study clearly demonstrated that it is not satisfactory when used exclusively as the only HPV detecting method. Adding ISH, although known as less sensitive than PCR-based detection methods, has the advantage to preserve the morphological context of HPV-DNA signals in FFPE samples and, thus increase the overall specificity of p16/Consensus PCR combination tests.

Developments in virus-like particle-based vaccines for infectious diseases and cancer

Virus-like particles hold great promise for the development of effective and affordable vaccines. Indeed, virus-like particles are suitable for presentation and efficient delivery of linear as well as conformational antigens to antigen-presenting cells. This will ultimately result in optimal B-cell activation and cross-presentation with both MHC class I and II molecules to prime CD4(+) T-helper as well as CD8(+) cytotoxic T cells. This article provides an update on the development and use of virus-like particles as vaccine approaches for infectious diseases and cancer.

Dendritic cells in the pathogenesis and treatment of human diseases: a Janus Bifrons?

Dendritic cells (DCs) represent the bridging cell compartment between a variety of nonself antigens (i.e., microbial, cancer and vaccine antigens) and adaptive immunity, orchestrating the quality and potency of downstream immune responses. Because of the central role of DCs in the generation and regulation of immunity, the modulation of DC function in order to shape immune responses is gaining momentum. In this respect, recent advances in understanding DC biology, as well as the required molecular signals for induction of T-cell immunity, have spurred many experimental strategies to use DCs for therapeutic immunological approaches for infections and cancer. However, when DCs lose control over such 'protective' responses - by alterations in their number, phenotype and/or function - undesired effects leading to allergy and autoimmune clinical manifestations may occur. Novel therapeutic approaches have been designed and currently evaluated in order to address DCs and silence these immunopathological processes. In this article we present recent concepts of DC biology and some medical implications in view of therapeutic opportunities.

Effects of adjuvants on IgG subclasses elicited by virus-like particles

BACKGROUND

Virus-Like Particles (VLPs) represent an efficient strategy to present and deliver conformational antigens to the immune system, inducing both arms of the adaptive immune response. Moreover, their particulate structure surrounded by cell membrane provides an adjuvanted effect to VLP-based immunizations. In the present study, the elicitation of different patterns of IgG subclasses by VLPs, administered in CpG ODN1826 or poly(I:C) adjuvants, has been evaluated in an animal model.

RESULTS

Adjuvanted VLPs elicited a higher titer of total specific IgG compared to VLPs alone. Furthermore, while VLPs alone induced a balanced TH2 pattern, VLPs formulated with either adjuvant elicited a TH1-biased IgG subclasses (IgG2a and IgG3), with poly(I:C) more potent than CpG ODN1826.

CONCLUSIONS

The results confirmed that adjuvants efficiently improve antigen immunogenicity and represent a suitable strategy to skew the adaptive immune response toward the differentiation of the desired T helper subset, also using VLPs as antigen.