PI3K/AKT/mTOR signaling pathway: an important driver and therapeutic target in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor lacking estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. It has higher aggressiveness and metastasis than other subtypes, with limited effective therapeutic strategies, leading to a poor prognosis. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway is prevalently over-activated in human cancers and contributes to breast cancer (BC) growth, survival, proliferation, and angiogenesis, which could be an interesting therapeutic target. This review summarizes the PI3K/AKT/mTOR signaling pathway activation mechanism in TNBC and discusses the relationship between its activation and various TNBC subtypes. We also report the latest clinical studies on kinase inhibitors related to this pathway for treating TNBC. Our review discusses the issues that need to be addressed in the clinical application of these inhibitors.

Ginsenosides: changing the basic hallmarks of cancer cells to achieve the purpose of treating breast cancer.

In 2021, breast cancer accounted for a substantial proportion of cancer cases and represented the second leading cause of cancer deaths among women worldwide. Although tumor cells originate from normal cells in the human body, they possess distinct biological characteristics resulting from changes in gene structure and function of cancer cells in contrast with normal cells. These distinguishing features, known as hallmarks of cancer cells, differ from those of normal cells. The hallmarks primarily include high metabolic activity, mitochondrial dysfunction, and resistance to cell death. Current evidence suggests that the fundamental hallmarks of tumor cells affect the tissue structure, function, and metabolism of tumor cells and their internal and external environment. Therefore, these fundamental hallmarks of tumor cells enable tumor cells to proliferate, invade and avoid apoptosis. Modifying these hallmarks of tumor cells represents a new and potentially promising approach to tumor treatment. The key to breast cancer treatment lies in identifying the optimal therapeutic agent with minimal toxicity to normal cells, considering the specific types of tumor cells in patients. Some herbal medicines contain active ingredients which can precisely achieve this purpose. In this review, we introduce Ginsenoside's mechanism and research significance in achieving the therapeutic effect of breast cancer by changing the functional hallmarks of tumor cells, providing a new perspective for the potential application of Ginsenoside as a therapeutic drug for breast cancer.

Flagellin modulates IgE expression in B cells to initiate food allergy in mice.

The initiation mechanism of IgE expression has not been fully understood. Flagellin (FGN) is an important microbial factor in the regulation of immune responses in the intestine. This study tests a hypothesis that FGN plays a crucial role in the isotype switching of IgE in B cells and the initiation of food allergy. In this study, the expression of IgE in B cells was analyzed by real time RT-PCR, Western blotting and chromatin immunoprecipitation. A mouse model was developed to assess the role of Toll like receptor-5 in the development of IgE-mediated allergic reaction in the intestinal mucosa. The results showed that exposure to FGN suppressed the expression of Bcl6 in B cells via increasing the levels of histone deacetylase (HDAC) 7; the latter up regulated the levels of methylated H3K9 and H3K27, down regulated RNA polymerase II and STAT3 (signal transducer and activator of transcription 3) at the Bcl6 promoter locus. Exposure to FGN and IL-4 markedly increased the expression of IgE in B cells via activating p300, H3K4, Pol II and STAT6 at the IgE promoter locus. As compared with the sensitized wild mice, the sensitized TLR5-deficient mice showed no detectable OVA-specific IgE in the serum; mast cells in the intestinal mucosa were not activated, no apparent allergic symptoms were evoked after the specific antigen challenge. In conclusion, FGN facilitates the initiation of food allergy in mice by triggering IgE transcription in B cells in a Th2 polarization environment via activating HDAC7 and suppressing Bcl6 expression.

Regulation of TWIK-related potassium channel-1 (Trek1) restitutes intestinal epithelial barrier function.

The disruption of epithelial barrier integrity is an important factor in the pathogenesis of various immune disorders. However, the restitution of the compromised barrier functions is difficult. This study investigates the regulation of TWIK-related potassium channel-1 (Trek1) in the restitution of intestinal epithelial barrier functions. The human colon epithelial cell line T84 was cultured in monolayers and used to observe epithelial barrier functions in vitro. An intestinal allergy mouse model was created. Cytokine levels were determined by enzyme-linked immunosorbent assay and western blotting. The results showed that Trek1 deficiency induced T84 monolayer barrier disruption. Allergic responses markedly suppressed the expression of Trek1 in the intestinal epithelia via activating the mitogen-activated protein kinase pathways and increasing the expression of histone deacetylase-1. The inhibition of histone deacetylase-1 by sodium butyrate or the administration of a butyrate-producing probiotic (Clostridium butyricum) restored the intestinal epithelial barrier functions and markedly enhanced the effect of antigen-specific immunotherapy. The data suggest that Trek1 is required for the maintenance of intestinal epithelial barrier integrity. Allergic responses induce an insufficiency of Trek1 expression in the intestinal epithelia. Trek1 expression facilitates the restoration of intestinal epithelial barrier functions in an allergic environment.

Interaction of TIM4 and TIM3 induces T helper 1 cell apoptosis.

The T helper 1 (Th1) polarization plays a critical role in the pathogenesis of a number of inflammatory disorders in the body; the remedies in the correction of polarized Th1 cells are limited. This study aims to investigate the role of T cell immunoglobulin mucin domain molecule 4 (TIM4) in the induction of Th1 cell apoptosis. In this study, polarized Th1 cells were generated from naive Th1 cells from the mouse spleen. Recombinant TIM4 was added to the culture to stimulate the polarized Th1 cells. The apoptosis of Th1 cells was assessed by flow cytometry. The expression of FasL was analyzed by chromatin immunoprecipitation, real time RT-PCR, and Western blotting. The results showed that the polarized Th1 cells expressed high levels of TIM3. After exposure of the polarized Th1 cells to TIM4 in the culture, a complex of TIM3 and TIM4 was detected on the surface of Th1 cells, which induced the Th1 cell apoptosis. The engagement of TIM3 by TIM4 increased p300 phosphorylation in Th1 cells, which further increased the levels of Fas ligand in the cells and induced Th1 cell apoptosis. In conclusion, TIM4 binds TIM3 on the surface of polarized Th1 cells to induce Th1 cell apoptosis, which may contribute to the development of Th2-dominant immune disorders.

Insulin-like growth factor-1 endues monocytes with immune suppressive ability to inhibit inflammation in the intestine.

The pathogenesis of some chronic inflammation such as inflammatory bowel disease is unclear. Insulin-like growth factor-1 (IGF1) has active immune regulatory capability. This study aims to investigate into the mechanism by which IGF1 modulates the monocyte (Mo) properties to inhibit immune inflammation in the intestine. In this study, the production of IGF1 by intestinal epithelial cells was evaluated by real time RT-PCR and Western blotting. Mos were analyzed by flow cytometry. A mouse colitis model was created with trinitrobenzene sulfonic acid. The results showed that mouse IECs produced IGF1, which could be up regulated by exposure to CpG-ODN (CpG-oligodeoxynueleotides) in the culture. Culture the CpG-ODN-primed IEC cells and Mos or exposure of Mos to IGF1 in the culture induced the Mos to express IL-10. The IGF1-primed Mos showed the immune suppressive effect on inhibiting the immune inflammation in the mouse colon. In conclusion, the IGF1-primed Mos are capable of suppressing immune inflammation in the intestine.

Prolactin mediates psychological stress-induced dysfunction of regulatory T cells to facilitate intestinal inflammation.

OBJECTIVE: The dysfunction of immune regulation plays a critical role in the pathogenesis of a number of chronic inflammatory disorders, such as IBD. A close relationship between psychological stress and intestinal inflammation has been noted; the underlying mechanism remains elusive. This study aims to elucidate a pathological pathway between psychological stress and the dysfunction of regulatory T cells (Treg), and its effect on facilitating intestinal inflammation. DESIGN: A restraint stress model was employed to induce psychological stress in mice. The functions of Tregs were determined by assessing the immune suppressor effects in the intestine. A mouse model of intestinal inflammation was established using a low dose of trinitrobenzene sulfonic acid (TNBS) or dextran sulfate sodium (DSS) together with the challenge of chronic stress. RESULTS: After treating mice with restraint stress, the suppressor function of intestinal Treg was compromised, although the frequency of Treg was not changed in the intestine. Further observation revealed that stress induced Tregs in the intestine to differentiate into foxhead box P3(+) interleukin (IL)-17(+) tumour necrosis factor (TNF)-α(+) T cells. We also observed that exposure to stress-derived prolactin induced dendritic cells (DC) to produce IL-6 and IL-23 in vitro and in vivo, which played a critical role in altering Treg's phenotypes. Treating mice with chronic stress facilitated the initiation of intestinal inflammation by a low dose of TNBS or DSS, which was abolished by pretreatment with an inhibitor of prolactin, the cabergoline. CONCLUSIONS: Psychological stress-derived prolactin alters DC and Treg's properties to contribute to intestinal inflammation.

Cigarette smoke extract stimulates rat pulmonary artery smooth muscle cell proliferation via PKC-PDGFB signaling.

Accumulating evidence suggests a direct role for cigarette smoke in pulmonary vascular remodeling, which contributes to the development of pulmonary hypertension. However, the molecular mechanisms underlying this process remain poorly understood. Platelet-derived growth factor (PDGF) is a potential mitogen and chemoattractant implicated in several biological processes, including cell survival, proliferation, and migration. In this study, we investigated the effect of cigarette smoke extract (CSE) on cell proliferation of rat pulmonary artery smooth muscle cells (rPASMCs). We found that stimulation of rPASMCs with CSE significantly increased cell proliferation and promoted cell cycle progression from G1 phase to the S and G2 phases. CSE treatment also significantly upregulated the mRNA and protein levels of PDGFB and PDGFRß. Our study also revealed that Rottlerin, an inhibitor of PKCδ signaling, prevented CSE-induced cell proliferation, attenuated the increase of S and G2 phase populations induced by CSE treatment, and downregulated PDGFB and PDGFRß mRNA and protein levels in rPASMCs exposed to CSE. Collectively, our data demonstrated that CSE-induced cell proliferation of rPASMCs involved upregulation of the PKCδ-PDGFB pathway.

Expression of ß1,3-N-acetylglucosaminyltransferases during differentiation of human acute myeloid leukemia cells.

The expressions of ß1,3-N-acetylglucosamonyltransferase-2 and -8 (ß3GnT-2, ß3GnT-8),-the two main glycosyltransferases responsible for the synthesis of poly-N-acetyllactosamine (polyLacNAc) in glycans, and ß3GnT-5 participating in the syntheses of sphingoglycolipids were studied in leukemia cell lines during differentiation using RT-PCR method. ß3GnT-2 and ß3GnT-8 distribute widely in six myeloid and monocytoid leukemia cell lines with different abundances, while ß3GnT-4 was only present in NB4 cells. ATRA (all-trans retinoic acid) and dimethylsulfoxide (DMSO), which induce the differentiation of HL-60 and NB4 (two human acute myeloid leukemia cell lines) to myelocytic lineage, up-regulated these two enzymes with various degrees at 2 and 72 h of treatment. In HL-60 cells treated with ATRA, the increase of ß3GnT-8 was more than ß3GnT-2, while in NB4 cells treated with DMSO, the increase of ß3GnT-2 was more than ß3GnT-8. However, when HL-60 and NB4 were differentiated to monocytic lineage induced by phorbol 12-myristate 13-acetate the expressions of ß3GnT-2 and ß3GnT-8 showed no alterations or the increase of expressions was far less than those in myelocytic differentiation. By means of FITC-labeled tomato lectin affinity staining and flow-cytometry, it was found that the product of ß3GnT-2 and -8, polyLacNAc was also increased on the cell surface of HL-60 and NB4 treated with ATRA or DMSO, but unchanged when treated with PMA. These results were in accordance with the up-regulation of the mRNAs of ß3GnT-2 and -8. The expression of ß3GnT-5, however, was not changed both in myelocytic and monocytic differentiations. The difference in the up-regulation of ß3GnT-2 and -8, especially their products may become a useful index to discriminate the myelocytic and monocytic differentiation of leukemia cells.

[Effect of protein kinase C-nuclear factor-kappa B signal transduction pathway on proliferation and expression of vascular endothelial growth factor in human pulmonary artery smooth muscle cells].

OBJECTIVE: To investigate the effect of protein kinase C (PKC)-nuclear factor-kappa B (NF-kappaB) signal transduction pathway on proliferation and expression of vascular endothelial growth factor (VEGF) in human pulmonary artery smooth muscle cells (HPASMCs). METHODS: Cultured HPASMCs in normoxia or hypoxia conditions were divided into three groups and stimulated with or without phorbol 12-myristate 13-acetate (PMA) and pyrrolidine dithiocarbamate (PDTC) in vitro. The three groups were the control group, the PMA group and the PMA + PDTC group. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect VEGF mRNA expression, and the expression of VEGF protein and the inhibitor protein IkappaBalpha were observed by Western blot, while the location and expression of NF-kappaB p65 were observed by immunocytochemical staining, and cell cycle phases were analyzed by flow cytometry. RESULTS: (1) As for the positive rate of nucleolar staining for NF-kappaB p65, the relative expression of IkappaBalpha protein, and the percentage of G(2)/M phases of cell cycle, there were significant differences between the PMA group and the control group or PMA + PDTC group, both in normoxia and hypoxia conditions (P < 0.05, respectively), and there was also a significant difference between the normoxia and hypoxia PMA groups (P < 0.05). (2) There were no significant differences in VEGF mRNA and protein expression among the three groups (P > 0.05, respectively) in normoxia, but the expression was higher in hypoxia PMA group than in hypoxia control and hypoxia PMA + PDTC or normoxia PMA group (P < 0.05, respectively). (3) There was a positive correlation between the positive rate of nucleolar staining for NF-kappaB p65, the relative expression of VEGF protein and the percentage of G(2)/M phases of cell cycle in hypoxia PMA group (r = 0.587 - 0.710, P < 0.05, respectively). CONCLUSIONS: There is a signal transduction pathway of PKC-NF-kappaB in HPASMCs. The activity of PKC can be enhanced in hypoxia, concomitant NF-kappaB activation or VEGF overexpression to be involved in the proliferation. These results suggest that the activation of NF-kappaB can be considered as a downstream of PKC signal transduction pathway, and the activation of PKC-NF-kappaB signal transduction pathway and VEGF overexpression may contribute to the process of hypoxic pulmonary hypertension.

[Expression of protein kinase C and nuclear factor kappa B in lung tissue of patients with chronic obstructive pulmonary disease].

OBJECTIVE: To investigate the expression changes of protein kinase C (PKC) and nuclear factor kappa B (NF-kappaB) in lung tissue of patients with chronic obstructive pulmonary disease (COPD). METHODS: The lung tissues obtained from 15 patients (A group) without COPD and 15 patients (B group) with COPD matched with A group in age and sex undergoing pneumonectomy for peripheral lung cancer. The protein and mRNA level of PKCalpha was determined by using Western blot analysis and reverse transcription polymerase chain reaction respectively. NF-kappaB p65 nuclei positive expression was observed by immunohistochemical technique. Electrophoretic mobility shift assay was used to detect the NF-kappaB/DNA binding activity. RESULTS: (1) Forced expiratory volume in one second (FEV1)/forced vital capacity (FVC), FEV1(%Pre) and partial pressure of oxygen in artery (PaO2) of B group were significantly lower than that of A group (t=7.73-13.96, P <0.01, respectively). (2) There was higher level of PKCalpha/GAPDH mRNA and the relative expression of PKCalpha protein in B group than in A group (t=7.64 and 22.27, P <0.01, respectively). (3) There were significant increases in NF-kappaB p65 nuclei positive expression of B group than that of A group (t=112.79, P <0.01). The NF-kappaB/DNA binding activity of B group was approximately 3.2-fold that of A group (t=104.80, P <0.01). (4) There was a significant negative correlation between PaO2 and the nuclei positive expression rate of NF-kappaB p65 in 15 cases of B group (r=-0.7090, P <0.05). CONCLUSION: The expression of PKCalpha, NF-kappaB p65 nuclei positive expression rate and NF-kappaB/DNA binding activity significantly increase in lung tissues of patients with COPD, suggesting that the activation of PKC and NF-kappaB may contribute to the process of COPD in human.