Vol 32, No 3 (2017)

Ductal adenocarcinoma is one of the most common and severely aggressive forms of pancreatic cancer. IGF-I is one of the factors that ensures survival and proliferation of tumor cells, and its increased concentration inside the tumor is a characteristic sign of many malignant formations. The goal of this minireview is to provide an up-to-date insight on the roles of the IGF-I/IGF-IR signaling pathway in carcinogenesis and potential opportunities for pharmacologic targeting of IGF-I/IGF-IR in pancreatic tumors.

We have cloned the promoter of the human PCNA gene that codes for a proliferating cell-nuclear antigen. Two promoter DNA fragments were cloned of 1416 and 389 bp in length. Expression of luc and PDX1 genes under the control of the PCNA promoter was demonstrated in transient and stable transfection in human and mouse cell lines. We have shown that PCNA promoter within genetically engineered vectors is able to promote efficient expression of heterologous genes at a level comparable to a widely used CMV promoter. In particular, we report a comparative analysis of expression of PDX1, a master regulator gene in the pancreas, under PCNA promoter in pancreatic cancer cells. We propose that PCNA promoter can be used as a universal one in the design of therapeutic gene constructs.

The formation of biofilms by M. tuberculosis on Shkolnikova’s medium (synthetic medium, analogue of Sauton’s medium) has been researched. We studied 150 clinical and 20 laboratory strains of M. tuberculosis. None of the 150 strains isolated from human beings produced biofilms (pellicle), but all yielded abundant planktonic growth. Twenty reference strains of M. tuberculosis produced both biofilms (pellicle) and planktonic growth. The phenomenon of biofilm formation by mixed cultures was observed when inoculating sputum treated with NALC-NaOH from patients with tuberculosis. We obtained 63 mixed biofilms. In 30.2% (19/63) of cases, biofilms contained the DNA of the causative agent of tuberculosis. The RV-PCR method was used to select six samples with the highest concentration of mycobacterial DNA. Molecular cloning and sequencing of a fragment of the 16S rRNA gene from one of the biofilms was carried out. The nucleotide sequence had 99% homology with the Bacillus thermoamylovorans species. From the mixed biofilms obtained, three strains of spore-forming bacilli were isolated. Strains are identified by Sanger’s sequencing of the 16S rRNA gene, one as Bacillus licheniformis, and the other two as Brevibacillus spp. A study of the resistance of isolated strains of spore bacilli against 12 antituberculosis drugs of the first and second series was carried out. All three strains were resistant to maximum concentrations of isoniazid, streptomycin, ethionamide, and ethambutol. Strains of Brevibacillus spp. were additionally resistant to para-aminosalicylic acid (PAS) and kanamycin. In a model experiment, the possibility of cogrowth of clinical strains of M. tuberculosis and B. licheniformis was demonstrated with prolonged co-incubation in Shkolnikova’s medium. In the first few days of growth, B. licheniformis produced a biofilm that remained stable for the entire observation period of 45 days. The hypothesis suggesting the possibility of a short-term persistence of some “saprophytic” species of bacilli in the caseous contents of necrosis foci in the late stages of pulmonary tuberculosis has been postulated.

This study addresses a current problem of vaccinal prevention—the development of approaches to increase the immunogenicity of influenza vaccines—and it is directed at studying the effect of mutations responsible for the degree of attenuation of influenza viruses on the formation of an immune response. We conducted the analysis of the humoral and cellular immune response in mice with the introduction of strains of the influenza A virus containing single and combined point mutations alike typical for the attenuation donor A/Leningrad/134/17/57 (H2N2), which is used at present for the preparation of domestic live influenza vaccine. In the study, 13 mutant strains were compared to the attenuation donor (containing all these mutations) and its “wild” predecessor (without mutations). It has been shown that the presence in internal genes of the “wild” virus of single mutations that are typical for the attenuation donor, as well as their combinations, can affect not only the quantitative indices of the humoral immune response, but also the rate of accumulation of virus-specific serum and secretory antibodies. A group of viruses with mutations in the M1 gene was isolated based on the ability to stimulate T cell response. A promising approach to development of ways to increase the immunogenic properties of live influenza vaccines will be a further search for a balanced combination of mutations in M1 and NS2 genes that enhance the stimulation of most of the immuneresponse factors studied, with mutations in genes of polymerase complex that impart attenuating properties to strains.