A comparison of the human and mouse protein corona profiles of functionalized SiO2 nanocarriers.

Nanoparticles are a promising cancer therapy for their use as drug carriers given their versatile functionalization with polyethylene glycol and proteins that can be recognized by overexpressed receptors in tumor cells. However, it has been suggested that in biological fluids, proteins cover nanoparticles, which gives the proteins a biological identity that could be responsible for unexpected biological responses: the so-called protein corona. A relevant biological event that is usually ignored in protein-corona formation is the interspecies differences in protein binding, which can be involved in the discrepancies observed in preclinical studies and the nanoparticle safety and efficiency. Hence, the aim of this study was to determine the differences between human and mouse plasma protein corona profiles in an active therapy model using silicon dioxide nanoparticles (SiO2 nanoparticles) functionalized with polyethylene glycol and transferrin. Functionalized SiO2 nanoparticles were made with a primary particle size of 25 nm and a transferrin content of 50 µg mg-1 of nanoparticles and were PEGylated with a cross-linker. The proteomic analysis by nanoliquid chromatography tandem-mass spectrometry (nanoLC-MS/MS) showed interspecies differences. The most abundant proteins found in the human protein corona profile were immunoglobulins, actin cytoplasmic 1, hemoglobin subunit beta, serotransferrin, ficolin-3, complement C3, and apolipoprotein A-1. Meanwhile, the mouse protein corona adsorbed the serine protease inhibitor A3K, serotransferrin, alpha-1-antitrypsin 1-2, hemoglobin subunit beta, and fibrinogen gamma and beta chains. These protein-corona profile differences in the functionalized SiO2 nanoparticles indicate that biological responses observed in in vivo models could not be translated to clinical use and must be considered in the interpretation of preclinical trials in order to design more efficient and safer nanomedicines.

Histones and long non-coding RNAs: the new insights of epigenetic deregulation involved in oral cancer.

Oral squamous cell carcinoma (OSCC) is a category of aggressive malignancies that represent clinically, molecularly, and etiologically heterogeneous tumors. The majority of OSCCs are associated with tobacco and alcohol use, acting both independently and synergistically, which suggests that the environment plays an important role in carcinogenesis; however, the mechanisms associated with the development of OSCC are not well understood. It has been proposed that the epigenetic components could be implicated in the initiation and progression of OSCC. Primarily, aberrant DNA methylation patterns have been widely addressed in the study of OSCC. Diverse studies have proposed that other epigenetic processes such as post-translational histone modification, the deposition of histone variants, histone chaperones, and recently non-coding RNA, can be also involved in the development of oral cancer. In this review we focus on describing the new insights of the epigenetics processes that are related with OSCC as histones variants and long non-coding RNAs.

DNA methylation in oral squamous cell carcinoma: molecular mechanisms and clinical implications.

DNA methylation is an important regulator of gene transcription, and its role in carcinogenesis has been a topic of considerable interest in the last few years. Of the all epigenetic modifications, methylation, which represses transcription of the promoter region of tumor suppressor genes leading to gene silencing, has been most extensively studied. Oral squamous cell carcinoma (OSCC) has long been known to be the endpoint of many genetic changes, not only genomic mutations but also abnormal epigenetic modifications, as such, promoter methylation, contribute to development of this tumors. Recent studies have shown that promoter methylation of tumor suppressor genes is an important factor in carcinogenesis of OSCC. Some of the main genes that frequently showed promoter methylation in OSCC are those that participate in diverse processes such as regulation of the cell cycle, DNA repair, proliferation, and apoptosis. The aim of this review is to assess the current state of knowledge regarding promoter methylation of diverse genes in OSCC.

hMLH1 promoter methylation is an early event in oral cancer.

Promoter methylation is believed to inactivate the expression of hMLH1. This process has been implicated in the tumorigenesis of oral squamous cell carcinoma (OSCC). Thus, the aim of this study was to determine the profile of hMLH1 methylation and protein expression in OSCC. The matched case-control study included 50 OSCC cases and 200 controls, with a median of age 64 (Q1-Q3 54-71) years. Protein expression was determined by immunohistochemical staining, and hMLH1 gene promoter methylation was analyzed by methylation-specific polymerase chain reaction (MSP). A conditional logistic regression model for risk factors was built for OSCC cases and matched controls. Promoter methylation of hMLH1 was detected in 38 (76%) OSCC cases, but in none of the control samples. Of the 38 OSCC samples with promoter methylation, 12 (32%) were negative for hMLH1 protein, and corresponded to early clinical stages (10 in stage II and 2 in stage I). All 12 unmethylated samples showed positive stain for hMLH1. Multiple logistic regression analysis showed an OR of 16.54 (IC 95%: 1.69-161.68, p=0.016) for methylation of the hMLH1 gene and early stages of OSCC, adjusting by gender and tobacco use. This study showed a high frequency of hMLH1 promoter methylation that occurred in most of the early stage cases and in about half of the late stage cases. It is proposed that hMLH1 promoter methylation is an early event that is maintained during tumor progression.

Mortality due to lung cancer in Mexico.

The highest mortality due to cancer worldwide for both genders corresponds to lung cancer (1,179,000 deaths). In Mexico, the crude mortality rate due to lung cancer was of 5.01 per 10(5) inhabitants in 1979. The most important risk factor is smoking. The present study was aimed at analyzing the mortality due to lung cancer in Mexico, assessing data from each of the states constituting the Mexican Republic during the 1998-2004 period. Data were obtained from the National Institute of Statistics, Geography and Informatics (INEGI, for its initials in Spanish) corresponding to deaths due to lung cancer (1998-2004). We estimated the mean annual mortality rate (MAMR) for each of the 32 states of Mexico. We used the "World Population Standard". The MAMR was standardized according to age (ARS) direct method, and the standard error was determined by Poisson's approximation at a 95% confidence interval. To know the excess risk due to mortality, we calculated the standardized mortality ratios (SMRs) of ARS for each federal state, using the national rate as reference. In this period, 397,400 deaths due to malignant neoplasms were recorded, corresponding 45,578 (11.5%) to lung cancer; for men, 31,025 (68.1%) with MAMR of 8.9 and the respective ARS of 13.2 both x10(5) inhabitants. For women, results were 4553 (31.9%) deaths with MAMR of 4.1 and ARS of 5.4 both x10(5) inhabitants. The highest mortality rates due to lung cancer in both genders were observed in the north of Mexico, whereas for women this was observed in the central states. Although smoking is the main risk for lung cancer, there are other factors such as environmental pollution or exposure to toxicants that could be associated to this cancer. The years potentially lost due to lung cancer were 258,550 for men and 133,315 for women, with a total of 391,865 according to histopathology registry neoplasm malignant RHNM (1985-1995). Studies focused on the characterization and measurement of polluting agents would be a good start to determine the level of participation of air pollution in the development of lung cancer.

Mutational analysis of K-ras and Ras protein expression in larynx squamous cell carcinoma.

The ras gene family (H, K and N-ras) encodes the Ras protein, a GTPase-activating protein that regulates several signal transduction pathways including cellular proliferation and differentiation. Mutations in codons 12, 13 and 61 of the ras genes constitute one of the most frequent alterations in human cancer. In the Western Hemisphere, a low frequency of mutations in these genes has been observed in head and neck carcinomas; a higher frequency has been found in countries such as India and Taiwan. Increased protein expression is a relatively frequent event in larynx carcinomas. This study was aimed to evaluate the participation of the k-ras gene and Ras expression in 20 Mexican patients with larynx squamous carcinoma, 2 with dysplasia and 4 with normal mucosa. Samples (of 26 patients) were embedded in paraffin and immunohistochemical analysis was performed for the Ras protein, as well as amplification of the k-ras gene exon 1 (108 bp) by laser capture microdissection. Then, DNA extraction, PCR and sequencing were performed looking for possible mutation in codons 12 and 13. All patients with larynx carcinoma were men, median age 62 years. Eighty-five percent of the patients had risk factors such as smoking and/or alcohol consumption, 25% were in clinical stages I and II, and 75% in stages III and IV; 45% of the patients presented tumor recurrence or persistence. In this study, no mutations were found in codons 12 or 13 of the k-ras gene; however, protein expression was observed in 95% of the samples and a higher expression of the protein was associated with tumor recurrence or persistence, although this was not statistically significant. Unexpectedly, well-differentiated carcinomas and dysplasias presented an increase in protein expression. These results suggest that ras may be involved in early stages of larynx carcinogenesis and may be activated by other mechanisms different from mutations, such as epigenetic events.

A 24-kDa cloned zinc metalloprotease from Actinobacillus pleuropneumoniae is common to all serotypes and cleaves actin in vitro.

Actinobacillus pleuropneumoniae causes pleuropneumonia in swine. This bacterium secretes proteases that degrade porcine hemoglobin and IgA in vitro. To further characterize A. pleuropneumoniae proteases, we constructed a genomic library expressed in Escherichia coli DH5alpha, and selected a clone that showed proteolytic activity. The recombinant plasmid carries an 800-base pair A. pleuropneumoniae gene sequence that.codes for a 24-kDa polypeptide. A 350-base pair PstI fragment from the sequence hybridized at high stringency with DNA from 12 serotypes of A. pleuropneumoniae, but not with DNA from Actinobacillus suis, Haemophilus parasuis, Pasteurella haemolytica, Pasteurella multocida A or D, or E. coli DH5alpha, thus showing specificity for A. pleuropneumoniae. The expressed polypeptide was recognized as an antigen by convalescent-phase pig sera. Furthermore, a polyclonal antiserum developed against the purified polypeptide recognized an A. pleuropneumoniae oligomeric protein in both crude-extract and cell-free culture media. This recombinant polypeptide cleaved azocoll, gelatin, and actin. Inhibition of the proteolytic activity by diethylpyrocarbonate suggests that this polypeptide is a zinc metalloprotease.

Human cervical cancer-associated nuclear matrix proteins.

The nuclear matrix is the nonchromatin protein structural component of the nucleus that governs nuclear shape and also exerts regulatory control over higher order gene organization. Recent studies have documented the presence of tumor-associated nuclear matrix proteins in several human cancers. We used high-resolution two-dimensional gel electrophoresis to compare nuclear matrix protein patterns in cervical carcinomas with those from normal cervical tissue. Tumors obtained from 20 patients undergoing hysterectomy for clinically localized cervical cancer were compared with normal cervical tissue. We have identified five polypeptides (CvC-1: Mr = 69,408 Da, pI = 5. 78; CvC-2: Mr = 53,752 Da, pI = 5.54; CvC-3: Mr = 47,887 Da, pI = 5. 60; CvC-4: Mr = 46,006 Da, pI = 5.07; and CvC-5: Mr = 44,864 Da, pI = 6.61) in the nuclear matrix from cervical carcinomas that were present in 20 of 20 cervical tumors but 0 of 10 normal tissues. These data extend similar findings of cancer-associated nuclear matrix proteins in other human cancers and suggest that nuclear matrix proteins may represent a new class of cancer markers that could aid the diagnosis or management of some types of cancer.

Kdp-like system in Salmonella typhimurium LT-2.

Salmonella typhimurium LT-2, as Escherichia coli K12, was able to grow in a potassium concentration-dependent manner, down to a very low concentration (< 5 microM). Its metabolic swelling also was [K+]-dependent. When the cells were subjected to hyperosmotic shock, this ion was uptaken rapidly, probably due to a K(+)-high affinity transport-system, similar to the E. coli Kdp system. The shrinkage in presence of 0.6 M NaCl, however, was more noticeable in S. typhimurium, which expressed a smaller level of intracellular K+ than E. coli. The genetic locus responsible for the ability of S. typhimurium to grow in low [K+], was mapped in nitrosoguanidine mutants and localized around min 18, close to the gal operon. This asseveration was confirmed by experiments of reversion, conjugation, and transduction. The mutants required considerably more [K+] to grow and to swell than the parental strain; in addition, below 1 mM [K+], they showed less internal [K+].