Macrophage inflammatory protein-2 contributes to liver resection-induced acceleration of hepatic metastatic tumor growth

Adjuvant transarterial chemoembolization timing after radical resection is an independent prognostic factor for patients with hepatocellular carcinoma

Background

It has been reported that postoperative adjuvant TACE (PA-TACE) treatment decreases recurrence and significantly improves the survival of patients who undergo radical resection of hepatocellular carcinoma (HCC) with high-risk recurrence factors. However, when to perform PA-TACE has not been fully studied.

Methods

We retrospectively collected the clinicopathologic characteristics of the patients with HCC between October 2013 and June 2020. The optimal cutoff value for PA-TACE time was determined based on the R package “maxstat”. Logistic regression and Cox regression analysis were used to determine the effect of the choice of PA-TACE timing on prognosis.

Results

The analysis was performed on 789 patients with HCC, and 484 patients were finally involved and were divided into training cohort (378) and validation cohort (106). The PA-TACE timing was found to be associated with survival outcomes. Multivariate logistic analysis found independent predictors of the PA-TACE timing, including gender and history of HBV. Multivariate Cox analysis showed that Ki-67, tumor size, MVI and the PA-TACE timing were independent prognostic factors for RFS in HCC patients.

Conclusions

Based on this study, HCC patients with high-risk recurrence factors can receive personalized assistance in undergoing PA-TACE treatment and improve their survival outcomes.

Adjuvant Transarterial Chemoembolization Following Curative-Intent Hepatectomy Versus Hepatectomy Alone for Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The role of adjuvant transarterial chemoembolization (TACE) for patients with resectable hepatocellular carcinoma (HCC) undergoing hepatectomy is currently unclear. We performed a systematic review of the literature using the MEDLINE, Embase, and Cochrane Library databases. Random-effects meta-analysis was carried out to compare the overall survival (OS) and recurrence-free survival (RFS) of patients with resectable HCC undergoing hepatectomy followed by adjuvant TACE vs. hepatectomy alone in randomized controlled trials (RCTs). The risk of bias was assessed using the Risk of Bias 2.0 tool. Meta-regression analyses were performed to explore the effect of hepatitis B viral status, microvascular invasion, type of resection (anatomic vs. parenchymal-sparing), and tumor size on the outcomes. Ten eligible RCTs, reporting on 1216 patients in total, were identified. The combination of hepatectomy and adjuvant TACE was associated with superior OS (hazard ratio (HR): 0.66, 95% confidence interval (CI): 0.52 to 0.85; p < 0.001) and RFS (HR: 0.70, 95% CI: 0.56 to 0.88; p < 0.001) compared to hepatectomy alone. There were significant concerns regarding the risk of bias in most of the included studies. Overall, adjuvant TACE may be associated with an oncologic benefit in select HCC patients. However, the applicability of these findings may be limited to Eastern Asian populations, due to the geographically restricted sample. High-quality multinational RCTs, as well as predictive tools to optimize patient selection, are necessary before adjuvant TACE can be routinely implemented into standard practice. PROSPERO Registration ID: CRD42021245758.

1-Palmitoyl-2-Linoleoyl-3-Acetyl-rac-Glycerol (PLAG) Rapidly Resolves LPS-Induced Acute Lung Injury Through the Effective Control of Neutrophil Recruitment

Acute lung injury (ALI) is an acute respiratory failure that is associated with excessive neutrophil recruitment and high mortality. To assess the efficacy of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) as a therapeutic agent for ALI, this compound was administered orally to mice challenged with an intranasal dose of lipopolysaccharide (LPS). Using this model, we found that PLAG promotes resolution of ALI through effective control of LPS-induced neutrophil infiltration, endothelial permeability, and inflammatory chemokine production. In addition, the Toll like Receptor 4 (TLR4) endocytosis/exocytosis cycle was significantly accelerated in Raw 264.7 cells co-treated with PLAG/LPS, as compared to cells treated only with LPS. During this cycle, a PLAG-induced exotoxin clearance pathway was observed to occur through the prompt assembly of nicotinamide adenine dinucleotide phosphate (NADPH) units and production of reactive oxygen species (ROS), which ultimately lead to earlier LPS clearance. We further detected reduced expression, as well as faster return to homeostatic levels, of macrophage inflammatory protein (MIP)-2, in PLAG/LPS- vs. LPS-treated cells. MIP-2 is a main inducer of neutrophil migration that is mainly controlled by interferon regulatory factor 3 (IRF3) activation and is involved in the TLR4 endosomal-signaling pathway. PLAG induced TLR4-mediated TRIF-related adaptor molecules/Toll-interleukin receptor (TIR) domain-containing adaptor protein including interferon (IFN)-β/IRF3 endosomal signaling, leading to rapid association of TRAM/TRIF and TLR4 and earlier IRF3 phosphorylation in PLAG/LPS-treated vs. LPS-treated cells. PLAG specificity was further verified with PLAG analogs and metabolites known to control excessive neutrophil infiltration, suggesting that this acetylated diacylglycerol has a unique biological role in neutrophil motility. Thus, our data indicate that PLAG may represent a potential therapeutic agent for resolution of LPS-induced lung inflammation through effective MIP-2 modulation.

HSP90 inhibitor PU-H71 increases radiosensitivity of breast cancer cells metastasized to visceral organs and alters the levels of inflammatory mediators

Heat shock protein 90 (HSP90) inhibitors are considered as new radiosensitizing agents. PU-H71, a novel HSP90 inhibitor, is under evaluation for the treatment of advanced cancer. It is however not known whether PU-H71 alters radiosensitivity of metastatic breast cancer. Hence, we here evaluated mechanisms of possible anti-tumoral and radiosensitizing effects of PU-H71 on breast carcinoma cells metastasized to vital organs such as the liver and brain. The effect of PU-H71 on proliferation of breast carcinoma cells was determined using 4T1 cells and its brain (4TBM), liver (4TLM), and heart (4THM) metastatic subsets as well as non-metastatic 67NR cells. Changes in radiation sensitivity were determined by clonogenic assays. Changes in client proteins and levels of angiogenic and inflammatory mediators from these cancer cell cultures and ex vivo cultures were detected. PU-H71 alone inhibited ERK1/2, p38, and Akt activation and reduced N-cadherin and HER2 which further documented the anti-tumoral effects of PU-H71. The combination of PU-H71 and radiotherapy induced cytotoxic effect than PU-H71 alone, and PU-H71 showed a radiosensitizing effect in vitro. On the other hand, PU-H71 and radiation co-treatment increased p38 phosphorylation which is one of the hallmarks of inflammatory response. Accordingly, IL-6 secretion was increased following PU-H71 and radiotherapy co-treatment ex vivo. Levels of angiogenic and inflammatory factors such as MIP-2, SDF-1, and VEGF were increased under in vitro conditions but not under ex vivo conditions. These results demonstrated for the first time that PU-H71 enhances therapeutic effects of radiotherapy especially in highly metastatic breast carcinoma but a possible increase in inflammatory response should also be considered.

Macrophage inflammatory protein-2 as mediator of inflammation in acute liver injury

Macrophage inflammatory protein (MIP)-2 is one of the CXC chemokines and is also known as chemokine CXC ligand (CXCL2). MIP-2 affects neutrophil recruitment and activation through the p38 mitogen-activated-protein-kinase-dependent signaling pathway, by binding to its specific receptors, CXCR1 and CXCR2. MIP-2 is produced by a variety of cell types, such as macrophages, monocytes, epithelial cells, and hepatocytes, in response to infection or injury. In liver injury, activated Kupffer cells are known as the major source of MIP-2. MIP-2-recruited and activated neutrophils can accelerate liver inflammation by releasing various inflammatory mediators. Here, we give a brief introduction to the basic molecular and cellular sources of MIP-2, and focus on its physiological and pathological functions in acute liver injury induced by concanavalin A, lipopolysaccharides, irradiation, ischemia/reperfusion, alcohol, and hypoxia, and hepatectomy-induced liver regeneration and tumor colorectal metastasis. Further understanding of the regulatory mechanisms of MIP-2 secretion and activation may be helpful to develop MIP-2-targeted therapeutic strategies to prevent liver inflammation.

Type conversion of secretomes in a 3D TAM2 and HCC cell co-culture system and functional importance of CXCL2 in HCC

Macrophages play important roles in the tumor microenvironment, driving cancer progression and metastasis, particularly in hepatocellular carcinoma (HCC). However, few studies have assessed the exact secretome composition in HCC. In the present study, the impact of different phenotype of macrophages on HCC cells was investigated. Alternatively activated macrophages (M2) were found to significantly increase the proliferation, migration, and invasion abilities of SMMC7721 cells (all P < 0.05). M2 were then co-cultured with SMMC7721 cells to reconstruct the tumor microenvironment. Conditioned medium from 3D single cultures of M2, SMMC7721 cells, and their co-culture system were analyzed using quantitative proteomics via iTRAQ labeling combined with mass spectrometric analysis. Secretome analysis revealed a total of 159 differential secreted proteins in the co-culture system compared to the single culture systems, with 63 being up-regulated (>1.3-fold) and 96 down-regulated (<0.7-fold). CXCL2 was confirmed to have higher expression in the co-culture system and HCC tissues, and was selected for further investigation. Functional effects data suggested that recombinant human CXCL2 significantly enhanced the migration, invasion ability of SMMC7721 cells, and weakened adhesion ability. While CXCL2 neutralization and CXCR2 blockage significantly inhibited the effects of CXCL2 on SMMC7721 cells, indicating that CXCL2 may play pivotal role in HCC metastasis.

Blastocystis sp. in Irritable Bowel Syndrome (IBS)--Detection in Stool Aspirates during Colonoscopy

Blastocystis is one of the most common gut parasites found in the intestinal tract of humans and animals. Its' association with IBS is controversial, possibly as a result of irregular shedding of parasites in stool and variation in stool detection. We aimed to screen for Blastocystis in colonic stool aspirate samples in adult patients with and without IBS undergoing colonoscopy for various indications and measure the interleukin levels (IL-8, IL-3 and IL-5). In addition to standard stool culture techniques, polymerase chain reaction (PCR) techniques were employed to detect and subtype Blastocystis. All the serum samples collected were subjected for ELISA studies to measure the interleukin levels (IL-8, IL-3 and IL-5). Among 109 (IBS n = 35 and non-IBS n = 74) adults, direct stool examination and culture of colonic aspirates were initially negative for Blastocystis. However, PCR analysis detected Blastocystis in 6 (17%) IBS and 4 (5.5%) non-IBS patients. In the six positive IBS patients by PCR method, subtype 3 was shown to be the most predominant (3/6: 50%) followed by subtype 4 (2/6; 33.3%) and subtype 5 (1/6; 16.6%). IL-8 levels were significantly elevated in the IBS Blasto group and IBS group (p<0.05) compared to non-IBS and non-IBS Blasto group. The level of IL-3 in were seen to be significantly higher in than IBS Blasto group and IBS group (p<0.05) compared to non-IBS. Meanwhile, the IL-5 levels were significantly higher in IBS Blasto group (p<0.05) compared to non-IBS and non-IBS Blasto group. This study implicates that detecting Blastosystis by PCR method using colonic aspirate samples during colonoscopy, suggests that this may be a better method for sample collection due to the parasite’s irregular shedding in Blastocystis-infected stools. Patients with IBS infected with parasite showed an increase in the interleukin levels demonstrate that Blastocystis does have an effect in the immune system.

Caught in the act: revealing the metastatic process by live imaging

The prognosis of metastatic cancer in patients is poor. Interfering with metastatic spread is therefore important for achieving better survival from cancer. Metastatic disease is established through a series of steps, including breaching of the basement membrane, intravasation and survival in lymphatic or blood vessels, extravasation, and growth at distant sites. Yet, although we know the steps involved in metastasis, the cellular and molecular mechanisms of dissemination and colonization of distant organs are incompletely understood. Here, we review the important insights into the metastatic process that have been gained specifically through the use of imaging technologies in murine, chicken embryo and zebrafish model systems, including high-resolution two-photon microscopy and bioluminescence. We further discuss how imaging technologies are beginning to allow researchers to address the role of regional activation of specific molecular pathways in the metastatic process. These technologies are shedding light, literally, on almost every step of the metastatic process, particularly with regards to the dynamics and plasticity of the disseminating cancer cells and the active participation of the microenvironment in the processes.

ERK2-dependent activation of c-Jun is required for nontypeable Haemophilus influenzae-induced CXCL2 upregulation in inner ear fibrocytes

The inner ear, composed of the cochlea and the vestibule, is a specialized sensory organ for hearing and balance. Although the inner ear has been known as an immune-privileged organ, there is emerging evidence indicating an active immune reaction of the inner ear. Inner ear inflammation can be induced by the entry of proinflammatory molecules derived from middle ear infection. Because middle ear infection is highly prevalent in children, middle ear infection-induced inner ear inflammation can impact the normal development of language and motor coordination. Previously, we have demonstrated that the inner ear fibrocytes (spiral ligament fibrocytes) are able to recognize nontypeable Haemophilus influenzae, a major pathogen of middle ear infection, and upregulate a monocyte-attracting chemokine through TLR2-dependent NF-κB activation. In this study, we aimed to determine the molecular mechanism involved in nontypeable H. influenzae-induced cochlear infiltration of polymorphonuclear cells. The rat spiral ligament fibrocytes were found to release CXCL2 in response to nontypeable H. influenzae via activation of c-Jun, leading to the recruitment of polymorphonuclear cells to the cochlea. We also demonstrate that MEK1/ERK2 signaling pathway is required for nontypeable H. influenzae-induced CXCL2 upregulation in the rat spiral ligament fibrocytes. Two AP-1 motifs in the 5'-flanking region of CXCL2 appeared to function as a nontypeable H. influenzae-responsive element, and the proximal AP-1 motif was found to have a higher binding affinity to nontypeable H. influenzae-activated c-Jun than that of the distal one. Our results will enable us better to understand the molecular pathogenesis of middle ear infection-induced inner ear inflammation.

Parenchyma-preserving hepatic resection for colorectal liver metastases

BACKGROUND

Hepatic resection of colorectal liver metastases is the only curative treatment option. As clinical and experimental data indicate that the extent of liver resection correlates with growth of residual metastases, the present study analyzes the potential benefit of a parenchyma-preserving liver surgery approach.

METHODS

Data from a prospectively maintained database of patients undergoing liver resection for colorectal metastases were reviewed. Evaluation of outcome was performed using the Kaplan-Meier method. Correlations were calculated between clinical-pathological variables.

RESULTS

One hundred sixty-three patients underwent 198 liver resections for colorectal metastases: 26 major hepatectomies, 65 minor anatomical resections, 78 non-anatomical resections, as well as 29 combinations of minor anatomical and non-anatomical procedures. Overall 1-, 3-, and 5-year survival was 93%, 62%, and 40%, respectively. Patients with repeated liver resections had a 5-year survival of 27%. Interestingly, large dissection areas were associated with a significant reduction of the 5-year survival rate (33%). Five-year survival after major hepatectomy was not significantly reduced.

CONCLUSION

For colorectal liver metastases, minor resections offer a prolonged survival compared to major hepatectomies. As patients with stage IV colorectal disease are candidates for repeat resections, preservation of hepatic parenchyma is of increasing importance in the setting of multi-modal and repeated therapy approaches.

Darbepoetin-α promotes neovascularization and cell proliferation in established colorectal liver metastases

BACKGROUND

The erythropoietin-analogue darbepoetin-α (DPO) improves liver function and regeneration after hepatectomy (Phx), however, also enhances Phx-induced tumor cell engraftment and neovascularization. Because it is unknown whether DPO also enhances the growth of established tumors, we herein studied the effect of DPO on established colorectal liver metastases after Phx.

METHODS

CT26.WT cells were implanted into the liver of BALB/c mice. Five days after tumor establishment, animals underwent 50% Phx and received 10 μg/kgBW DPO or saline. Non-Phx animals with DPO or saline-treatment served as controls. Seven days after Phx tumors were analyzed regarding blood vessel formation, leukocyte adhesion, cell proliferation, apoptotic cell death, and growth using intravital fluorescence microscopy, histology, and immunohistochemistry.

RESULTS

The growth of established colorectal liver metastases was slightly stimulated after DPO-treatment in hepatectomized and non-hepatectomized animals. However, tumor vessel formation and tumor cell proliferation were significantly enhanced after DPO-treatment in hepatectomized and non-hepatectomized mice compared with controls. Apoptotic cell death and leukocyte-endothelial cell interaction were significantly reduced after DPO-treatment.

CONCLUSION

Our study indicates that DPO-treatment promotes neovascularization and cell proliferation in established colorectal liver metastases of hepatectomized and non-hepatectomized mice. DPO-application in patients with colorectal liver metastases might promote tumor progression and should therefore be avoided.

Lymphotoxin-β receptor activation by lymphotoxin-α(1)β(2) and LIGHT promotes tumor growth in an NFκB-dependent manner

Lymphotoxin beta receptor (LTβR) activation on mouse fibrosarcoma cells (BFS-1) results in enhanced solid tumor growth paralleled by increased angiogenesis induced by the expression of pro-angiogenic CXCL2. In our study, we demonstrate that both functional ligands of the LTβR, namely LTα(1) β(2) and LIGHT, are involved in the activation of LTβR in solid fibrosarcomas. To identify whether the lymphocyte population is involved in the activation of LTβR in these fibrosarcoma tumors, we used conditional LTβ-deficient mice that specifically lack LTβ expression either on T cells (T-LTβ(-/-)) or on B cells (B-LTβ(-/-)). Solid tumor growth was reduced in both mouse strains when compared to tumor growth in wild-type mice, indicating the participation of both T and B host lymphocytes in the activation of LTβR in these tumors. Tumor growth was also reduced in LIGHT-deficient mice, suggesting a contribution of this ligand to the activation of LTβR in BFS-1 fibrosarcomas. LTβR signaling can involve IκBα and/or NFκB-inducing kinase (NIK) for subsequent NFκB activation in different types of cells. Expression of a dominant negative form of IκBα or of a dominant negative mutant of NIK resulted in decreased activation of NFκB signaling and reduced expression of pro-angiogenic CXCL2 in vitro. Moreover, expression of dominant negative form of NIK or an IκBα repressor in these fibrosarcoma cells resulted in reduced solid tumor growth in vivo, suggesting that both IκBα and NIK are involved in pro-angiogenic signaling after LTβR activation. Our data support the idea that the ablation of LTβR signaling should be considered for cancer treatment.

CXCR4 and CXCR7 regulate angiogenesis and CT26.WT tumor growth independent from SDF-1

Recent studies have shown that the chemokine stromal cell-derived factor (SDF)-1 and its receptor CXCR4 are involved in the metastatic process of colorectal cancer. The impact of SDF-1 on the stimulated metastatic growth during hepatectomy-associated liver regeneration is unknown. With the use of a heterotopic murine colon cancer model, we analyzed whether blockade of SDF-1 inhibits angiogenesis and extrahepatic growth of colorectal cancer after liver resection. Functional neutralization of SDF-1 by 1 mg/kg body weight anti-SDF-1 antibody only slightly delayed the initial tumor cell engraftment but also did not reduce the size of established extrahepatic tumors compared with controls. Tumor cell apoptosis was increased by anti-SDF-1 treatment only during the early 5-9-day period of tumor cell engraftment, but was found significantly decreased during the late phase of tumor growth. The initial delay of tumor cell engraftment was associated with an increase of tumor capillary density and microvascular permeability. This was associated with an increased vascular endothelial growth factor (VEGF) expression and an enhanced tumor cell invasion of the neighboring tissue. In contrast to the neutralization of SDF-1, blockade of the SDF-1 receptors CXCR4 and CXCR7 significantly reduced tumor capillary density and tumor growth. Thus, our study indicates that neutralization of SDF-1 after hepatectomy is not capable of inhibiting angiogenesis and growth of extrahepatic colorectal tumors, because it is counteracted by the compensatory actions through an alternative VEGF-dependent pathway.

Liver regeneration and tumor stimulation--a review of cytokine and angiogenic factors

Liver resection for metastatic (colorectal carcinoma) tumors is often followed by a significant incidence of tumor recurrence. Cellular and molecular changes resulting from hepatectomy and the subsequent liver regeneration process may influence the kinetics of tumor growth and contribute to recurrence. Clinical and experimental evidence suggests that factors involved in liver regeneration may also stimulate the growth of occult tumors and the reactivation of dormant micrometastases. An understanding of the underlying changes may enable alternative strategies to minimize tumor recurrence and improve patient survival after hepatectomy.

Liver regeneration and tumor stimulation--a review of cytokine and angiogenic factors

Liver resection for metastatic (colorectal carcinoma) tumors is often followed by a significant incidence of tumor recurrence. Cellular and molecular changes resulting from hepatectomy and the subsequent liver regeneration process may influence the kinetics of tumor growth and contribute to recurrence. Clinical and experimental evidence suggests that factors involved in liver regeneration may also stimulate the growth of occult tumors and the reactivation of dormant micrometastases. An understanding of the underlying changes may enable alternative strategies to minimize tumor recurrence and improve patient survival after hepatectomy.

Liver resection-associated macrophage inflammatory protein-2 stimulates engraftment but not growth of colorectal metastasis at extrahepatic sites

BACKGROUND

Previous studies have shown that liver resection enhances intrahepatic engraftment of CXCR-2-expressing colorectal cancer cells by the action of the CXC chemokine macrophage inflammatory protein (MIP)-2. Herein we studied how liver resection-associated MIP-2 affects extrahepatic tumor cell engraftment and whether MIP-2 also stimulates the growth of already established metastases.

MATERIALS AND METHODS

Green fluorescent protein-transfected CT26.WT colorectal cancer cells were implanted into dorsal skinfold chambers of syngeneic BALB/c mice. Additionally, all animals underwent a 30% hepatectomy. To study MIP-2 in extrahepatic tumor cell engraftment, animals were treated with an anti-MIP-2 antibody, starting at the day of tumor cell implantation. To study MIP-2 in established metastases, anti-MIP-2 treatment was initiated at day 5 after tumor cell implantation. Hepatectomized animals without neutralization of MIP-2 served as controls. Tumor vascularization and growth as well as tumor cell migration, proliferation, apoptosis, and CXCR-2 expression were studied over 14 days using intravital fluorescence microscopy, histology, and immunohistochemistry.

RESULTS

Functional inhibition of MIP-2 significantly delayed extrahepatic tumor cell engraftment but not the growth of established metastases. The initial delay of engraftment was associated with a compensatory stimulation of vascularization and tumor cell migration when compared to controls (P < 0.05). Further, inhibition of tumor cell engraftment by initial anti-MIP-2 treatment was associated with a significant (P < 0.05) reduction of CXCR-2 expression and tumor cell apoptosis.

CONCLUSION

Our study indicates that MIP-2 is involved in extrahepatic engraftment of CT.26 colorectal cancer cells. The MIP-2/CXCR-2 signaling pathway may be a promising target for early antitumor therapy in patients undergoing liver resection.

Major but not minor hepatectomy accelerates engraftment of extrahepatic tumor cells

BACKGROUND

The effect of hepatectomy and hepatic regeneration on intra- and extrahepatic tumor growth is still controversially discussed. Herein we studied the effect of minor (30%) or major (70%) hepatectomy on engraftment of extrahepatic tumor cells, and the role of tumor neovascularization and tumor cell migration.

METHODS

Green fluorescent protein (GFP)-transfected CT26.WT colorectal cancer cells were implanted in dorsal skinfold chambers of syngeneic BALB/c mice. Animals underwent 30% (30%Phx, n = 8) or 70% hepatectomy (70%Phx, n = 8). Sham-operated animals served as controls (n = 8). Angiogenesis and neovascularization as well as tumor cell migration, proliferation and growth were studied over 14 days using intravital fluorescence microscopy, histology and immunohistochemistry.

RESULTS

After both minor and major hepatectomy tumor proliferating cell nuclear antigen (PCNA) expression increased significantly (P < 0.05) when compared with nonhepatectomized controls. However, only major but not minor hepatectomy accelerated neovascularization (P < 0.05) and tumor cell migration (P < 0.05). This was associated with a significantly (P < 0.05) enhanced tumor growth after 70%Phx when compared with 30%Phx and controls. The rate of apoptotic cell death was not affected by major or minor hepatectomy.

CONCLUSION

Regeneration after major hepatectomy accelerates extrahepatic tumor cell engraftment, most probably by acceleration of neovascularization and induction of tumor cell migration.

Perspectives of micronuclear test in human lymphocytes cultivated in cytogenetic block conditions. Part 1: Cell proliferation

Cultivation of human blood lymphocytes under the conditions of cytokinetic block with cytochalasin B creates unique opportunity to analyze the total spectrum of the changes describing genome instability. The main task of the present publication is the analysis of a modern state, opportunities and outlooks of the micronuclear test on human blood lymphocytes. The special attention is given those directions of researches which are rather seldom present in the literature - to laws of cellular proliferation, to existence of physiological conditionality and genetic predisposition to development of effects of genome instability; to effects of emotional stress and the adaptive response to action of ionizing irradiation, etc. The material is presented in 2 consecutive publications. It is finished with discussion of methodical features of statement of culture, results of the microscopic analysis and ideology of creation of the conclusions of the study.