Multidrug resistance (MDR) of tumor cells is the resistance to a broad spectrum of structurally unrelated cytotoxic drugs with different mechanisms of action. One of the main causes of MDR phenotype is the activity of ATP-binding cassette transporters (ABC transporters). ABC transporters efflux toxic compounds from the cells. All living cells contain ABC transporters. This review is dedicated to the studies of three-dimensional structure of ABC transporters, to the data concerning MDR evolution in tumor cell populations. Some information 
about molecular mechanisms of MDR evolution is also presented.

Interaction of the extracellular domains of the transmembrane proteins cadherins provides cell-cell adhesion. For many years epithelial E- cadherin was regarded as a tumor suppressor and was used as a prognostic marker in cancer. Suppression of E-cadherin expression was observed in many carcinomas. During recent years, the tumor suppressor function of E-cadherin is being reconsidered. It has been shown that ductal breast carcinomas, colorectal carcinomas, oral cavity carcinomas, and squamous cell carcinomas of the head and neck can retain E-cadherin expression. Immunohistochemical staining with a panel of monoclonal antibodies revealed membrane localization of E-cadherin in many tumors. It was shown that transformed epithelial cells in vitro form dynamic adherens junctions that are essential for the effective collective migration of these cells.

Over the last forty years antiestrogen tamoxifen belongs to the most effective antitumor drugs widely used in the treatment of breast cancer, however, the efficiency of tamoxifen therapy is often limited by development of tumor hormonal resistance. The study of the mechanism of hormonal resistance led to the significant progress in the insight in signaling pathways respondent for the cancer cell growth in the absence of estrogen. In the review we have analyzed the recent data including our results obtained in the N. N. Blokhin RCRC, concerned with the study of the new aspects of hormonal resistance – the involvement of hypoxia-dependent HIF-1α / VEGF pathway, epithelial-mesenchymal transition and mTOR / AMPK in the formation of estrogen-independent phenotype. Some of the signaling proteins are considered as the potential targets for the therapy of the estrogen-resistant breast cancer.

The basic contemporary data and the results of authors’ long-term personal research devoted to the role of auto / paracrine growth factors, their receptors and some down-stream signaling proteins (PI3K, Akt, NF-κB) in clinical course, prognosis and development of hormonal and drug sensitivity of various human tumors are reviewed. The data on the key targeted drugs suppressing various growth factor signaling pathways components are summarized with special attention to the criteria of assessment of individual sensitivity to these drugs including those based on modern molecular biologic technologies.

Numerous studies have shown that approximately 20 % of all human tumors are neoplasms of an infectious nature. This review is an attempt to summarize the current understanding of the role of known human oncogenic viruses and their genetic variants on the risk of the human cancers development, as well as to show the existing measures of specific prevention of virus-induced tumors. It was paid also attention to the interaction between viral and cellular proteins, including tumor suppressors, and to the evaluation the significance of this interaction for specific oncogenic viruses and virus-associated tumors.

Viruses are associated with nearly 20 % of human cancers worldwide. Until recently genetic abnormalities generated by oncogenic viruses
in cells were the main object of studies. Understanding of the importance of epigenetics in the regulation of gene expression prompted the investigation of virus and host interactions at the epigenetic level. We review aspects such as common futures of oncogenic virus interactions with cell epigenetic system and virus-specific peculiarities of these interactions. Knowledge of the regulation of virus genomes by cell epigenetic system and disturbances of this system by viruses should provide us with markers for following cancer progression, as well as new tools for cancer therapy

The mechanisms of anticancerogenic effects of flavanoids and isocyanates from the plants widely consumed in the midland belt of Russia were reviewed. Data of studies both in vitro and in vivo were analyzed. Special attention was paid to inhibition of targets responsible for carcinogen metabolic activation, carcinogenesis promotion and tumor progression as well as neoangiogenesis. Besides that the antioxidant properties of flavonoids and their effects on cell cycle regulation, apoptosis initiation and cell mobility were considered.

The paper reviews modern concepts of serological tumor markers and their place in oncology: using for differential diagnostics, in the prognosis of the tumor, follow-up and for preclinical revealing of relapses, as well as in the screening aimed at early detection of malignant neoplasms. Biochemical characteristics and functions of most informative tumor markers (CA125, PSA etc.) were described. Currently diagnostic indexes, obtained by the in vitro diagnostic multivariate index assay (IVDMIA), and algorithms using several serological markers begin to apply in laboratory practice to increase diagnostic accuracy. Also some promising new serological tumor markers were described in this review.