Chemoradiotherapy-induced ACKR2+ tumor cells drive CD8+ T cell senescence and cervical cancer recurrence.

Tumor recurrence after chemoradiotherapy is challenging to overcome, and approaches to predict the recurrence remain elusive. Here, human cervical cancer tissues before and after concurrent chemoradiotherapy (CCRT) analyzed by single-cell RNA sequencing reveal that CCRT specifically promotes CD8+ T cell senescence, driven by atypical chemokine receptor 2 (ACKR2)+ CCRT-resistant tumor cells. Mechanistically, ACKR2 expression is increased in response to CCRT and is also upregulated through the ligation of CC chemokines that are produced by activated myeloid and T cells. Subsequently, ACKR2+ tumor cells are induced to produce transforming growth factor ß to drive CD8+ T cell senescence, thereby compromising antitumor immunity. Moreover, retrospective analysis reveals that ACKR2 expression and CD8+ T cell senescence are enhanced in patients with cervical cancer who experienced recurrence after CCRT, indicating poor prognosis. Overall, we identify a subpopulation of CCRT-resistant ACKR2+ tumor cells driving CD8+ T cell senescence and tumor recurrence and highlight the prognostic value of ACKR2 and CD8+ T cell senescence for chemoradiotherapy recurrence.

DNA-PK-Mediated Cytoplasmic DNA Sensing Stimulates Glycolysis to Promote Lung Squamous Cell Carcinoma Malignancy and Chemoresistance.

Detection of cytoplasmic DNA is an essential biological mechanism that elicits IFN-dependent and immune-related responses. A better understanding of the mechanisms regulating cytoplasmic DNA sensing in tumor cells could help identify immunotherapeutic strategies to improve cancer treatment. Here we identified abundant cytoplasmic DNA accumulated in lung squamous cell carcinoma (LUSC) cells. DNA-PK, but not cGAS, functioned as a specific cytoplasmic DNA sensor to activate downstream ZAK/AKT/mTOR signaling, thereby enhancing the viability, motility, and chemoresistance of LUSC cells. DNA-PK-mediated cytoplasmic DNA sensing boosted glycolysis in LUSC cells, and blocking glycolysis abolished the tumor-promoting activity of cytoplasmic DNA. Elevated DNA-PK-mediated cytoplasmic DNA sensing was positively correlated with poor prognosis of human patients with LUSC. Targeting signaling activated by cytoplasmic DNA sensing with the ZAK inhibitor iZAK2 alone or in combination with STING agonist or anti-PD-1 antibody suppressed the tumor growth and improved the survival of mouse lung cancer models and human LUSC patient-derived xenografts model. Overall, these findings established DNA-PK-mediated cytoplasmic DNA sensing as a mechanism that supports LUSC malignancy and highlight the potential of targeting this pathway for treating LUSC. SIGNIFICANCE: DNA-PK is a cytoplasmic DNA sensor that activates ZAK/AKT/mTOR signaling and boosts glycolysis to enhance malignancy and chemoresistance of lung squamous cell carcinoma.

Targeted Deletion of Rictor in BMSCs Reduces the Biological Activity of K7M2 Cells and Mitigates OS-Induced Bone Destruction.

Bone marrow mesenchymal stem cells (BMSCs) are indispensable cells constituting the bone marrow microenvironment that are generally recognized as being involved in the development and progression of osteosarcoma (OS). To explore whether mTORC2 signaling inhibition in BMSCs suppressed OS growth and tumor-caused bone destruction, 3-month-old littermates genotyped Rictorflox/flox or Prx1-cre; Rictorflox/flox (with same gender) were injected with K7M2 cells in the proximal tibia. After 40 days, bone destruction was alleviated in Prx1-cre; Rictorflox/flox mice, as observed on X-ray and micro-CT. This was accompanied by decreased serum N-terminal propeptide of procollagen type I (PINP) levels and reduced tumor bone formation in vivo. Interactions between K7M2 and BMSCs were studied in vitro. Rictor-deficient BMSCs, which were cultured in tumor-conditioned medium (TCM), caused reduced bone proliferation and suppressed osteogenic differentiation. Moreover, compared with the control group, K7M2 cells cultured in BCM (culture medium extracted from Rictor-deficient BMSCs) displayed less proliferation, migration, and invasion, and attenuated osteogenic activity. Forty types of cytokines were then analyzed by mouse cytokine array and decreased levels CCL2/3/5 and interleukin-16 were detected in Rictor-deficient BMSCs. These results suggested that inhibition of mTORC2 (Rictor) signaling pathway in BMSCs exerted anti-OS effects through 2 mechanisms: (1) by suppressing the proliferation and osteogenic differentiation of BMSCs induced by OS to alleviate bone destruction; (2) by reducing the secretion of cytokines by BMSCs, which are closely related to OS cell growth, migration, invasion, and tumorigenic osteogenesis.

Water-soluble BODIPY-nido-carborane nanoparticles applied to biocompatibility tumor cell imaging.

In this article, o-carborane has a high boron content, high hydrophobicity, and good chemical stability. It has been widely used in the fields of biology and medicine, especially in the application of boron neutron capture therapy (BNCT). However, o-carborane is a fat-soluble compound, its hydrophobicity is too strong, and its bioavailability is poor. This project aims to improve the water solubility of o-carborane drugs, so that the drugs can reach specific sites. For this reason, this article provides a one-pot reaction for the synthesis of water-soluble boron-containing drugs. 2-Chloro-1-(difluoroboranyl)-5-((4-ethyl-3,5-dimethyl-2H-pyrrol-2-ylidene)(phenyl) methyl)-1H-pyrrole and ethylenediamine are used as raw materials to synthesize fluorescent molecular probe BODIPY-NH2, and the fluorescent molecular probe is reacted with P-CBMA (poly(carboxybetaine methacrylate)) to produce a water-soluble gel polymer. Water-soluble o-carborane polymers were synthesized by hydrogen bonding of the polymers with bis(4-azaspiro[3.4]octan-4-ium)-nido-ortho-carborane and bis(5-azaspiro[4.5]decan-5-ium)-nido-ortho-caborane. The two polymers were characterized and the results showed that the maximum UV absorption wavelength of the two boron polymers in different polar solutions was 530-540 nm. In the fluorescence spectrum, the maximum emission wavelengths of the two boron polymers are concentrated between 550 and 560 nm. Through electron microscopy imaging, the fluoroboron pyrrole polymers wrap the boron clusters to form a spherical stacked. Through fluorescent cell imaging, both boron polymers can enter target cells.

A critical analysis of SARS-CoV-2 (COVID-19) complexities, emerging variants, and therapeutic interventions and vaccination strategies.

Coronavirus is a family of viruses that can cause diseases such as the common cold, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). The universal outbreak of coronavirus disease 2019 (COVID-19) caused by SARS coronaviruses 2 (SARS-CoV-2) has become a global pandemic. The ß-Coronaviruses, which caused SARS-CoV-2 (COVID-19), have spread in more than 213 countries, infected over 81 million people, and caused more than 1.79 million deaths. COVID-19 symptoms vary from mild fever, flu to severe pneumonia in severely ill patients. Difficult breathing, acute respiratory distress syndrome (ARDS), acute kidney disease, liver damage, and multi-organ failure ultimately lead to death. Researchers are working on different pre-clinical and clinical trials to prevent this deadly pandemic by developing new vaccines. Along with vaccines, therapeutic intervention is an integral part of healthcare response to address the ongoing threat posed by COVID-19. Despite the global efforts to understand and fight against COVID-19, many challenges need to be addressed. This article summarizes the current pandemic, different strains of SARS-CoV-2, etiology, complexities, surviving medications of COVID-19, and so far, vaccination for the treatment of COVID-19.

PELI1 promotes radiotherapy sensitivity by inhibiting noncanonical NF-κB in esophageal squamous cancer.

The low sensitivity of radiotherapy is the main cause of tumor tolerance against ionizing radiation (IR). However, the molecular mechanisms by which radiosensitivity is controlled remain elusive. Here, we observed that high expression of pellino E3 ubiquitin protein ligase 1 (PELI1) was correlated with improved prognosis in human esophageal squamous cell carcinoma stage III patients that received adjuvant radiotherapy. Moreover, we found PELI1-mediated IR-induced tumor cell apoptosis in vivo and in vitro. Mechanistically, PELI1 mediated the lysine 48 (Lys48)-linked polyubiquitination and degradation of NF-κB-inducing kinase (NIK; also known as MAP3K14), the master kinase of the noncanonical NF-κB pathway, thereby inhibiting IR-induced activation of the noncanonical NF-κB signaling pathway during radiotherapy. As a consequence, PELI1 inhibited the noncanonical NF-κB-induced expression of the anti-apoptotic gene BCL2 like 1 (Bclxl; also known as BCL2L1), leading to an enhancement of the IR-induced apoptosis signaling pathway and ultimately promoting IR-induced apoptosis in tumor cells. Therefore, Bclxl or NIK knockdown abolished the apoptosis-resistant effect in PELI1-knockdown tumor cells after radiotherapy. These findings establish PELI1 as a critical tumor intrinsic regulator in controlling the sensitivity of tumor cells to radiotherapy through modulating IR-induced noncanonical NF-κB expression.

Resveratrol (RV): A pharmacological review and call for further research.

Resveratrol (RV) is a well-known polyphenolic compound in various plants, including grape, peanut, and berry fruits, which is quite famous for its association with several health benefits such as anti-obesity, cardioprotective neuroprotective, antitumor, antidiabetic, antioxidants, anti-age effects, and glucose metabolism. Significantly, promising therapeutic properties have been reported in various cancer, neurodegeneration, and atherosclerosis and are regulated by several synergistic pathways that control oxidative stress, cell death, and inflammation. Similarly, RV possesses a strong anti-adipogenic effect by inhibiting fat accumulation processes and activating oxidative and lipolytic pathways, exhibiting their cardioprotective effects by inhibiting platelet aggregation. The RV also shows significant antibacterial effects against various food-borne pathogens (Listeria, Campylobacter, Staphylococcus aureus, and E. coli) by inhibiting an electron transport chain (ETC) and F0F1-ATPase, which decreases the production of cellular energy that leads to the spread of pathogens. After collecting and analyzing scientific literature, it may be concluded that RV is well tolerated and favorably affects cardiovascular, neurological, and diabetic disorders. As such, it is possible that RV can be considered the best nutritional additive and a complementary drug, especially a therapeutic candidate. Therefore, this review would increase knowledge about the blend of RV as well as inspire researchers around the world to consider RV as a pharmaceutical drug to combat future health crises against various inhumane diseases. In the future, this article will be aware of discoveries about the potential of this promising natural compound as the best nutraceuticals and therapeutic drugs in medicine.

BFAR coordinates TGFß signaling to modulate Th9-mediated cancer immunotherapy.

TGFß is essential for the generation of anti-tumor Th9 cells; on the other hand, it causes resistance against anti-tumor immunity. Despite recent progress, the underlying mechanism reconciling the double-edged effect of TGFß signaling in Th9-mediated cancer immunotherapy remains elusive. Here, we find that TGFß-induced down-regulation of bifunctional apoptosis regulator (BFAR) represents the key mechanism preventing the sustained activation of TGFß signaling and thus impairing Th9 inducibility. Mechanistically, BFAR mediates K63-linked ubiquitination of TGFßR1 at K268, which is critical to activate TGFß signaling. Thus, BFAR deficiency or K268R knock-in mutation suppresses TGFßR1 ubiquitination and Th9 differentiation, thereby inhibiting Th9-mediated cancer immunotherapy. More interestingly, BFAR-overexpressed Th9 cells exhibit promising therapeutic efficacy to curtail tumor growth and metastasis and promote the sensitivity of anti-PD-1-mediated checkpoint immunotherapy. Thus, our findings establish BFAR as a key TGFß-regulated gene to fine-tune TGFß signaling that causes Th9 induction insensitivity, and they highlight the translational potential of BFAR in promoting Th9-mediated cancer immunotherapy.

The ubiquitin ligase Peli1 inhibits ICOS and thereby Tfh-mediated immunity.

T follicular helper (Tfh) cells are crucial for regulating autoimmune inflammation and protective immunity against viral infection. However, the molecular mechanism controlling Tfh cell differentiation is poorly understood. Here, through two mixed bone marrow chimeric experiments, we identified Peli1, a T cell-enriched E3 ubiquitin ligase, as an intrinsic regulator that inhibits Tfh cell differentiation. Peli1 deficiency significantly promoted c-Rel-mediated inducible T-cell costimulator (ICOS) expression, and PELI1 mRNA expression was negatively associated with ICOS expression on human CD4+ T cells. Mechanistically, increased ICOS expression on Peli1-KO CD4+ T cells enhanced the activation of PI3K-AKT signaling and thus suppressed the expression of Klf2, a transcription factor that inhibits Tfh differentiation. Therefore, reconstitution of Klf2 abolished the differences in Tfh differentiation and germinal center reaction between WT and Peli1-KO cells. As a consequence, Peli1-deficient CD4+ T cells promoted lupus-like autoimmunity but protected against H1N1 influenza virus infection in mouse models. Collectively, our findings established Peli1 as a critical negative regulator of Tfh differentiation and indicated that targeting Peli1 may have beneficial therapeutic effects in Tfh-related autoimmunity or infectious diseases.

Modulation of M2 macrophage polarization by the crosstalk between Stat6 and Trim24.

Stat6 is known to drive macrophage M2 polarization. However, how macrophage polarization is fine-tuned by Stat6 is poorly understood. Here, we find that Lys383 of Stat6 is acetylated by the acetyltransferase CREB-binding protein (CBP) during macrophage activation to suppress macrophage M2 polarization. Mechanistically, Trim24, a CBP-associated E3 ligase, promotes Stat6 acetylation by catalyzing CBP ubiquitination at Lys119 to facilitate the recruitment of CBP to Stat6. Loss of Trim24 inhibits Stat6 acetylation and thus promotes M2 polarization in both mouse and human macrophages, potentially compromising antitumor immune responses. By contrast, Stat6 mediates the suppression of TRIM24 expression in M2 macrophages to contribute to the induction of an immunosuppressive tumor niche. Taken together, our findings establish Stat6 acetylation as an essential negative regulatory mechanism that curtails macrophage M2 polarization.

Peli1 controls the survival of dopaminergic neurons through modulating microglia-mediated neuroinflammation.

Chronic neuroinflammation is known to contributes to the toxicity of neurodegeneration of Parkinson's disease (PD). However, the molecular and cellular mechanisms controlling inflammatory responses in the central nervous system remain poorly understood. Here we found that a E3 ubiquitin ligase Peli1 is dramatically induced only in the substantia nigra (SN) of the human and mouse PD brains. The ablation of Peli1 significantly suppressed LPS-induced production of neurotoxic mediators and proinflammatory cytokines in SN and in primary microglia, whereas Peli1 is dispensable for the inflammatory responses in astrocyte. Accordingly, Peli1 deficiency markedly inhibited neuron death induced by the conditioned medium from LPS-stimulated microglia. Mechanistical study suggested that Peli1 acts as a positive regulator of inflammatory response in microglia through activation of NF-κB and MAP kinase. Our results established Peli1 as a critical mediator in the regulation of microglial activation and neuroinflammation-induced death of dopaminergic neurons during PD pathogenesis, suggesting that targeting Peli1 may have therapeutic effect in neuroinflammation.

A polymorphism within the mismatch repair gene predicts prognosis and adjuvant chemotherapy benefit in gastric cancer.

BACKGROUND: Defective mismatch repair (dMMR) and microsatellite instability (MSI) correlate with gastric cancer (GC) outcome. We hypothesized that MMR genetic polymorphisms that have low-penetrant effects but may cause heterogeneous MMR capability among individuals also affect GC outcome. METHODS: The polymorphisms rs1800734 in MLH1, rs2303428 and rs3732183 in MSH2, rs735943 in EXO1, and rs11797 in TREX1 were selected and analyzed in independent discovery and validation sets that included 167 and 593 patients, respectively. MSI was determined. RESULTS: In both the discovery and validation sets, the rs2303428 TC + CC genotype correlated with poor overall survival (OS) in non-cardia (P < 0.05) but not in cardia GC. Multivariate models showed that for OS of patients with non-cardia GC, the rs2303428 TC + CC genotype was an independent predictor in the validation set (HR 1.54; 95% CI 1.02-2.32; P = 0.040) and had a trend to be an independent predictor in the discovery set (HR 1.70; 95% CI 0.96-3.01; P = 0.067). Furthermore, in both patient sets, fluoropyrimidines-based adjuvant chemotherapy improved OS for non-cardia patients with the rs2303428 TC + CC genotype (HR 0.14; 95% CI 0.04-0.57; P = 0.006; and HR 0.29; 95% CI 0.15-0.58; P < 0.001, respectively) but not for those with the TT genotype. The rs2303428 genotypes were not associated with MSI frequency. The rs2303428 TC + CC genotype correlated with reduced expressions for thymidylate synthetase, P-glycoprotein and ERCC1 (P < 0.05) in non-cardia GC. CONCLUSIONS: The rs2303428 genotypes may predict prognosis and adjuvant chemotherapy benefit in non-cardia GC patients.

Association Between the Microsatellite Instability Status and the Efficacy of Postoperative Adjuvant Chemoradiotherapy in Patients With Gastric Cancer.

Purpose: The effect of microsatellite instability (MSI) on the response to radiotherapy remains unknown. The aim of this study was to investigate the association between the MSI status and the outcomes of gastric cancer (GC) treated by surgical resection with or without postoperative adjuvant chemoradiotherapy. Methods: The records of patients who underwent surgical resection of stage IB-III GC with or without postoperative adjuvant chemoradiotherapy were retrospectively retrieved from the Affiliated Hospital of Jiangsu University (n = 89), The Cancer Genome Atlas (n = 202), and the Asian Cancer Research Group (n = 138). The primary endpoint was overall survival (OS). Results: The MSI status had no significant influence on OS in all cohorts. Compared with surgery alone, adjuvant chemoradiotherapy improved or tended to improve OS of patients with stage III disease, irrespective of the MSI status, in all cohorts. Among patients with stage Ib/II disease, only those with microsatellite stability (MSS) benefited from chemoradiotherapy in terms of OS, whereas those with MSI showed no improvement in OS. A comparison of gene expression profiles between MSI stage Ib/II GC and MSS stage Ib/II GC revealed that MSI correlated with the overexpression of thymidylate synthetase, a marker of fluoropyrimidine resistance. Furthermore, tumor hypoxia scoring for stage Ib/II lesions showed significantly greater hypoxia in MSI tumors than in MSS tumors. Conclusions: The findings of this study suggest that postoperative adjuvant chemoradiotherapy is effective for stage III GC, regardless of the MSI status. However, MSI may predict a poor response to postoperative adjuvant chemoradiotherapy in patients with stage Ib/II GC.

Poly IC pretreatment suppresses B cell-mediated lupus-like autoimmunity through induction of Peli1.

Noncanonical NF-κB pathway is essential for the B cell activation and antibody production, which centralize the critical role of B cells in regulating the pathogenesis of systemic lupus erythematosus (SLE). We have previously demonstrated that Pellino1 (Peli1) negatively regulates noncanonical NF-κB activation and lupus autoimmunity. Here, we showed that poly IC is a potent inducer of Peli1 protein in mouse splenic B cells in dose- and time-dependent manners, and poly IC-induced Peli1 protein dramatically suppressed the activation of noncanonical NF-κB pathway. In addition, poly IC-pretreated B cells failed to induce lupus-like disease in BM12 CD4+ T cell-immunized mice. Accordingly, the induction of antibody-producing plasma cells and germinal center B cells, as well as the production of autoantibodies were significantly impaired in immunized µMT mice that were transferred with poly IC-pretreated B cells. Our findings demonstrate that poly IC-induced Peli1 negatively regulates the noncanonical NF-κB pathway in the context of restraining the pathogenesis of lupus-like disease.

Peli1 negatively regulates noncanonical NF-κB signaling to restrain systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by uncontrolled secretion of autoantibodies by plasma cells. Although the functional importance of plasma cells and autoantibodies in SLE has been well established, the underlying molecular mechanisms of controlling autoantibody production remain poorly understood. Here we show that Peli1 has a B cell-intrinsic function to protect against lupus-like autoimmunity in mice. Peli1 deficiency in B cells induces autoantibody production via noncanonical NF-κB signaling. Mechanically, Peli1 functions as an E3 ligase to associate with NF-κB inducing kinase (NIK) and mediates NIK Lys48 ubiquitination and degradation. Overexpression of Peli1 inhibits noncanonical NF-κB activation and alleviates lupus-like disease. In humans, PELI1 levels negatively correlate with disease severity in SLE patients. Our findings establish Peli1 as a negative regulator of the noncanonical NF-κB pathway in the context of restraining the pathogenesis of lupus-like disease.

Lin28/microRNA-let-7a promotes metastasis under circumstances of hyperactive Wnt signaling in esophageal squamous cell carcinoma.

Dysregulation of micro (mi)RNA-let-7 has been associated with the development and prognosis of multiple cancer types. Lin28, a RNA-binding protein, plays a conserved role in regulating the maturation of let-7 family proteins. However, few studies have focused on the effects of Lin28/let-7 on Wnt-activated esophageal squamous cell carcinoma (ESCC). Analysis of the expression of let-7a, let-7b and let-7c in clinical tissues revealed that lower let-7a expression was correlated with higher tumor node metastasis staging and recurrence in patients with ESCC. Furthermore, it was demonstrated that let-7a was inversely correlated with the migration and invasion of ESCC cells. In addition, epithelial-mesenchymal transition, and the expression of VEGF-C and MMP9 were effectively decreased by let-7a-mimic or siRNA-Lin28 pretreatment. Mechanistically, Lin28 functioned as the key factor in signal transduction, which regulated the expression of let-7a and the downstream genes along the Wnt signaling pathway. Taken together, these findings identified a biochemical and functional association between Lin28/let-7a, and the Wnt pathway in ESCC cells.

Novel transduction of nutrient stress to Notch pathway by RasGRP3 promotes malignant aggressiveness in human esophageal squamous cell carcinoma.

In the process of enlarging of tumors, the dissolving tissue structures and remodeling endothelial cells for restoring gas exchange and nutritional support, further facilitate tumor cell invasion and metastasis. Activation of Ras plays a critical role in the development of esophageal squamous cell carcinoma (ESCC), but the underlying mechanisms remain poorly understood. We therefore investigated whether Ras guanyl-releasing protein 3 (RasGRP3), a Ras activator, could promote metastasis by inducing vascular regeneration and further epithelial-mesenchymal transition under nutrient stress (NS). In the present study, we explored that the accumulation of RasGRP3 regulated vascular endothelial growth factor-A production, co-stimulated Notch pathway with high expression of Notch intracellular domain (NICD) and Hes1. Moreover, ESCC cells under NS increased the expression of vimentin, Snail, Slug and MMP9 proteins; while inhibition of Notch activation by DAPT (a γ-secretase inhibitor) or RasGRP3-targeted RNA interference prevented from the effect. In conclusion, these findings provide a new insight into the upregulation of RasGRP3 involved in Notch pathway activation in the development of ESCC, especially under nutrient deprivation.

Sulforaphane Analogues with Heterocyclic Moieties: Syntheses and Inhibitory Activities against Cancer Cell Lines.

Recent studies have shown that sulforaphane (SFN) selectively inhibits the growth of ALDH⁺ breast cancer stem-like cells.Herein, a series of SFN analogues were synthesized and evaluated against breast cancer cell lines MCF-7 and SUM-159, and the leukemia stem cell-like cell line KG-1a. These SFN analogues were characterized by the replacement of the methyl group with heterocyclic moieties, and the replacement of the sulfoxide group with sulfide or sulfone. A growth inhibitory assay indicated that the tetrazole analogs 3d, 8d and 9d were significantly more potent than SFN against the three cancer cell lines. Compound 14c, the water soluble derivative of tetrazole sulfide 3d, demonstrated higher potency against KG-1a cell line than 3d. SFN, 3d and 14c significantly induced the activation of caspase-3, and reduced the ALDH⁺ subpopulation in the SUM159 cell line, while the marketed drug doxrubicin(DOX) increased the ALDH⁺ subpopulation.

p53 suppresses 14-3-3γ by stimulating proteasome-mediated 14-3-3γ protein degradation.

14-3-3 proteins are a family of highly conserved polypeptides that interact with a large number of proteins and play a role in a wide variety of cellular processes. 14-3-3 proteins have been demonstrated overexpressed in several cancers and serving as potential oncogenes. In a previous study we showed one isoform of the 14-3-3 family, 14-3-3γ was negatively regulated by p53 through binding to its promoter and inhibiting its transcription. In the present study we investigated both p53 and 14-3-3γ protein levels in human lung cancerous tissues and normal lung tissues. We found 14-3-3γ expression correlated to p53 overexpression in lung cancer tissues. Ecotopic expression of wild-type p53, but not mutant p53 (R175H) suppressed both endogenous and exogenous 14-3-3γ in colon and lung cancer cell lines. Further examination demonstrated that p53 interacted with C-terminal domain of 14-3-3γ and induced 14-3-3γ ubiquitination. MG132, a specific inhibitor of the 26S proteasome, could block the effect of p53 on 14-3-3γ protein levels, suggesting that p53 suppressed 14-3-3γ by stimulating the process of proteasome-mediated degradation of 14-3-3γ. These results indicate that the inhibitory effect of p53 on 14-3-3γ is mediated also by a post-transcriptional mechanism. Loss of p53 function may result in upregulation of 14-3-3γ in lung cancers.

The Helicobacter pylori protein CagM is located in the transmembrane channel that is required for CagA translocation.

Helicobacter pylori (H. pylori) is a human gastric pathogen that colonizes the stomach in more than 50 % of the world's human population. Infection with this bacterium can induce several gastric diseases ranging from gastritis to peptic ulcer and gastric cancer. Virulent H. pylori isolates harboring the cag pathogenicity island (cag PAI), which encodes a Type IV Secretion System (T4SS), form a pilus for the injection of its major virulence protein CagA into gastric cells. Several cag PAI genes have been identified as homologues of T4SS genes from Agrobacterium tumefaciens, while the other members in cag PAI still have no known function. We studied one of such proteins with unknown function, CagM, which was predicted to have a putative N-terminal signal sequence and at least three transmembrane helices. To determine the subcellular localization of CagM, we performed a cell fractionation procedure and produced rabbit anti-CagM polyclonal antibodies for immunoblotting assays. Furthermore, we generated an isogenic ΔcagM mutant to investigate the ability of CagA translocation compared with the wild-type NCTC 11637 strain using GES-1 and MKN-45 cell infection experiments. Our results indicated that CagM was mainly located in the bacterial membrane, partially located in the periplasm, and essential for CagA translocation both in GES-1 and MKN-45 cells, which suggested that CagM was one of the core members of Cag T4SS and localized in the transmembrane channel.