The effects of amino acid substitution of spike protein and genomic recombination on the evolution of SARS-CoV-2.

Over three years' pandemic of 2019 novel coronavirus disease (COVID-19), multiple variants and novel subvariants have emerged successively, outcompeted earlier variants and become predominant. The sequential emergence of variants reflects the evolutionary process of mutation-selection-adaption of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Amino acid substitution/insertion/deletion in the spike protein causes altered viral antigenicity, transmissibility, and pathogenicity of SARS-CoV-2. Early in the pandemic, D614G mutation conferred virus with advantages over previous variants and increased transmissibility, and it also laid a conservative background for subsequent substantial mutations. The role of genomic recombination in the evolution of SARS-CoV-2 raised increasing concern with the occurrence of novel recombinants such as Deltacron, XBB.1.5, XBB.1.9.1, and XBB.1.16 in the late phase of pandemic. Co-circulation of different variants and co-infection in immunocompromised patients accelerate the emergence of recombinants. Surveillance for SARS-CoV-2 genomic variations, particularly spike protein mutation and recombination, is essential to identify ongoing changes in the viral genome and antigenic epitopes and thus leads to the development of new vaccine strategies and interventions.

Smoke and Spike: Benzo[a]pyrene Enhances SARS-CoV-2 Infection by Boosting NR4A2-Induced ACE2 and TMPRSS2 Expression.

Cigarette smoke aggravates severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the underlying mechanisms remain unclear. Here, they show that benzo[a]pyrene in cigarette smoke extract facilitates SARS-CoV-2 infection via upregulating angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). Benzo[a]pyrene trans-activates the promoters of ACE2 and TMPRSS2 by upregulating nuclear receptor subfamily 4 A number 2 (NR4A2) and promoting its binding of NR4A2 to their promoters, which is independent of functional genetic polymorphisms in ACE2 and TMPRSS2. Benzo[a]pyrene increases the susceptibility of lung epithelial cells to SARS-CoV-2 pseudoviruses and facilitates the infection of authentic Omicron BA.5 in primary human alveolar type II cells, lung organoids, and lung and testis of hamsters. Increased expression of Nr4a2, Ace2, and Tmprss2, as well as decreased methylation of CpG islands at the Nr4a2 promoter are observed in aged mice compared to their younger counterparts. NR4A2 knockdown or interferon-λ2/λ3 stimulation downregulates the expression of NR4A2, ACE2, and TMPRSS2, thereby inhibiting the infection. In conclusion, benzo[a]pyrene enhances SARS-CoV-2 infection by boosting NR4A2-induced ACE2 and TMPRSS2 expression. This study elucidates the mechanisms underlying the detrimental effects of cigarette smoking on SARS-CoV-2 infection and provides prophylactic options for coronavirus disease 2019, particularly for the elderly population.

Innate and adaptive immunity to SARS-CoV-2 and predisposing factors.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), has affected all countries worldwide. Although some symptoms are relatively mild, others are still associated with severe and even fatal clinical outcomes. Innate and adaptive immunity are important for the control of SARS-CoV-2 infections, whereas a comprehensive characterization of the innate and adaptive immune response to COVID-19 is still lacking and the mechanisms underlying immune pathogenesis and host predisposing factors are still a matter of scientific debate. Here, the specific functions and kinetics of innate and adaptive immunity involved in SARS-CoV-2 recognition and resultant pathogenesis are discussed, as well as their immune memory for vaccinations, viral-mediated immune evasion, and the current and future immunotherapeutic agents. We also highlight host factors that contribute to infection, which may deepen the understanding of viral pathogenesis and help identify targeted therapies that attenuate severe disease and infection.

Heterogeneity, inherent and acquired drug resistance in patient-derived organoid models of primary liver cancer.

PURPOSE: We aimed to elucidate the applicability of tumor organoids for inherent drug resistance of primary liver cancer (PLC) and mechanisms of acquired drug resistance. METHODS: PLC tissues were used to establish organoids, organoid-derived xenograft (ODX) and patient-derived xenograft (PDX) models. Acquired drug resistance was induced in hepatocellular carcinoma (HCC) organoids. Gene expression profiling was performed by RNA-sequencing. RESULTS: Fifty-two organoids were established from 153 PLC patients. Compared with establishing PDX models, establishing organoids of HCC showed a trend toward a higher success rate (29.0% vs. 23.7%) and took less time (13.0 ± 4.7 vs. 25.1 ± 5.4 days, p = 2.28 × 10-13). Larger tumors, vascular invasion, higher serum AFP levels, advanced stages and upregulation of stemness- and proliferation-related genes were significantly associated with the successful establishment of HCC organoids and PDX. Organoids and ODX recapitulated PLC histopathological features, but were enriched in more aggressive cell types. PLC organoids were mostly resistant to lenvatinib in vitro but sensitive to lenvatinib in ODX models. Stemness- and epithelial-mesenchymal transition (EMT)-related gene sets were found to be upregulated, whereas liver development- and liver specific molecule-related gene sets were downregulated in acquired sorafenib-resistant organoids. Targeting the mTOR signaling pathway was effective in treating acquired sorafenib-resistant HCC organoids, possibly via inducing phosphorylated S6 kinase. Genes upregulated in acquired sorafenib-resistant HCC organoids were associated with an unfavorable prognosis. CONCLUSIONS: HCC organoids perform better than PDX for drug screening. Acquired sorafenib resistance in organoids promotes HCC aggressiveness via facilitating stemness, retro-differentiation and EMT. Phosphorylated S6 kinase may be predictive for drug resistance in HCC.

PLXDC2 enhances invadopodium formation to promote invasion and metastasis of gastric cancer cells via interacting with PTP1B.

Plexin-domain containing 2 (PLXDC2) has been reported as an oncoprotein in several human malignancies. However, its expression and roles in gastric cancer remain largely unclear. In this study, we found that PLXDC2 was highly expressed in gastric cancer tissues, and the expression levels were positively correlated with clinicopathological features, but negatively with the patients' outcome. Cox regression analysis identified PLXDC2 as an independent prognostic indicator for the patients. Knockdown of PLXDC2 markedly suppressed the in vitro invasion and in vivo metastasis of gastric cancer cells, while overexpression of PLXDC2 resulted in opposite effects. Mechanistically, PLXDC2 enhanced the level of phosphorylated Cortactin (p-Cortactin) by physically interacting with protein tyrosine phosphatase 1B (PTP1B), an important dephosphorylase, to prevent its dephosphorylating of p-Cortactin, thereby promoting the formation of invadopodia. Collectively, our results indicate that PLXDC2 contributes to the invasion and metastasis of gastric cancer by inhibiting PTP1B to facilitate the invadopodium formation, and may serve as a potential prognostic biomarker and a therapeutic target for this disease.

Robotic surgical system completed radical gastrectomy for gastric cancer after liver transplantation: case report and systematic review.

De novo gastric cancer (GC) is uncommon in clinic after liver transplantation. Until now, only a few cases have been reported, and radical resection combined with comprehensive treatment remains the major therapeutic method. Two patients with De novo GC after liver transplantation were successfully treated with D2 lymphadenectomy using da Vinci robotic surgery system at our Hospital. Both operations were successful, and the duration of case 1 and 2 was 315 and 275 minutes respectively, with the estimated blood loss of 145 and 125 mL. The patients were discharged on day 7 and 9 after surgery, and no complications occurred. Postoperative pathological stages were pT4aN3aM0, stage III B and pT4aN2M0, stage III A respectively. Case 2 developed gastric retention 3 weeks after operation, and gastroscopy revealed edema within anastomotic stoma. Conservative treatment using feeding jejunal tube was performed. After 2 weeks, normal diet was gradually restored. Patients were treated with SOX regimen 3 weeks and 2 months post operation. During follow-up period, patients were in good health without long-term complications. Therefore, GC surgery using Da Vinci robot surgery system after liver transplantation is safe and feasible.

MTMR2 promotes invasion and metastasis of gastric cancer via inactivating IFNγ/STAT1 signaling.

BACKGROUND: The aberrant expression of myotubularin-related protein 2 (MTMR2) has been found in some cancers, but little is known about the roles and clinical relevance. The present study aimed to investigate the roles and clinical relevance of MTMR2 as well as the underlying mechanisms in gastric cancer (GC). METHODS: MTMR2 expression was examined in 295 GC samples by using immunohistochemistry (IHC). The correlation between MTMR2 expression and clinicopathological features and outcomes of the patients was analyzed. The roles of MTMR2 in regulating the invasive and metastatic capabilities of GC cells were observed using gain-and loss-of-function assays both in vitro and in vivo. The pathways involved in MTMR2-regulating invasion and metastasis were selected and identified by using mRNA expression profiling. Functions and underlying mechanisms of MTMR2-mediated invasion and metastasis were further investigated in a series of in vitro studies. RESULTS: MTMR2 was highly expressed in human GC tissues compared to adjacent normal tissues and its expression levels were significantly correlated with depth of invasion, lymph node metastasis, and TNM stage. Patients with MTMR2high had significantly shorter lifespan than those with MTMR2low. Cox regression analysis showed that MTMR2 was an independent prognostic indicator for GC patients. Knockdown of MTMR2 significantly reduced migratory and invasive capabilities in vitro and metastases in vivo in GC cells, while overexpressing MTMR2 achieved the opposite results. MTMR2 knockdown and overexpression markedly inhibited and promoted the epithelial-mesenchymal transition (EMT), respectively. MTMR2 mediated EMT through the IFNγ/STAT1/IRF1 pathway to promote GC invasion and metastasis. Phosphorylation of STAT1 and IRF1 was increased by MTMR2 knockdown and decreased by MTMR2 overexpression accompanying with ZEB1 down-regulation and up-regulation, respectively. Silencing IRF1 upregulated ZEB1, which induced EMT and consequently enhanced invasion and metastasis in GC cells. CONCLUSIONS: Our findings suggest that MTMR2 is an important promoter in GC invasion and metastasis by inactivating IFNγ/STAT1 signaling and may act as a new prognostic indicator and a potential therapeutic target for GC.

[Feasibility of robotic surgical system in radical gastrectomy for gastric cancer after liver transplantation].

OBJECTIVE: To explore the feasibility and safety of robotic surgical system for radical gastrectomy after liver transplantation. METHODS: A 65-year-old male patient with gastric cancer after liver transplantation underwent radical distal subtotal gastrectomy using Da Vinci surgical system at the General Surgery Department of Southwest Hospital Affiliated to the Army Military Medical University on October 23,2018. The placement of Trocars was arranged using five-hole method. No metastatic tumors were found during intraperitoneal exploration and the first hepatic hilum was found to be wrapped with omentum majus. The tumor located at gastric antrum near the lesser curvature. Then the first and the second station lymph nodes were dissected successively. Distal gastrectomy, Billroth II and Brown anastomosis were performed. The anatomical changes of upper abdomen and gastric lymph reflux after liver transplantation were analyzed. RESULTS: Radical distal gastrectomy with D2 lymphadenectomy was successfully performed under the whole robotic surgical system. The operative time was 315 minutes,and blood loss was 145 ml. A total of 19 lymph nodes were dissected, of which 11 were metastatic lymph nodes. The operative difficulty was to separate the adhesion around the hepatic hilum precisely so as to avoid the damage of hepatic surface, as well as the colon hepatic flexure and duodenum which were closely adhered to hepatic hilum. Meanwhile,it was necessary to pay attention to protetion for the common bile duct and portal vein. The endoscopic wrist joint of the robot surgical system was flexible and delicate, which had obvious advantages in the process of anatomical separation of the adhesions among organs and adhesions around denuded common hepatic artery without normal vascular sheath. Semi-liquid diet was provided on the third day after operation. The immunosuppressants were resumed on the third day after operation. The patient was discharged on the 7th day postoperatively without any complications. There were no abdominal bleeding, incision infection,anastomotic leakage, anastomotic stenosis and other complications. Two months after operation, the patients diet and daily life is normal. CONCLUSION: The robotic surgical system is safe and feasible for gastric cancer surgery after liver transplantation.

NETO2 promotes invasion and metastasis of gastric cancer cells via activation of PI3K/Akt/NF-κB/Snail axis and predicts outcome of the patients.

Aberrant expression of neuropilin and tolloid-like 2 (NETO2) has been observed during the progression of some human carcinomas. However, the expression pattern and clinical relevance of NETO2 in gastric cancer (GC) remain to be elucidated. In this study, we found that NETO2 expression was higher in GC tissues compared with paired non-cancerous tissues. Moreover, the expression of NETO2 was positively correlated with clinical stage, invasion depth, lymph node metastasis, and tumor size, but inversely correlated with overall and disease-free survival rates. Cox regression analysis identified NETO2 as an independent prognostic indicator for GC patients. Overexpression of NETO2 facilitated migration and invasion of GC cells in vitro and metastasis in vivo in association with induction of epithelial-mesenchymal transition. Conversely, knockdown of NETO2 had the opposite effects. Mechanistically, silencing NETO2 reduced the phosphorylation of PI3K, AKT, and NF-κB p65 as well as the expression of Snail, whereas NETO2 overexpression achieved the opposite results. Furthermore, we identified TNFRSF12A as a mediator for NETO2 to activate PI3K/AKT/NF-κB/Snail axis. Collectively, our results demonstrate that NETO2 promotes invasion and metastasis of GC cells and represents a novel prognostic indicator as well as a potential therapeutic target in GC.

[Application of robotic surgery to treat carcinoma in the remnant stomach].

OBJECTIVE: To explore the surgical techniques and feasibility of robotic surgery for carcinoma in the remnant stomach(CRS). METHODS: Clinicopathological data of 20 CRS patients undergoing robotic surgery at the Minimally Invasive Center for Gastrointestinal Surgery, Army Medical University Southwest Hospital from November 2012 to October 2017 were retrospectively collected. The surgical methods, procedures, main difficulties, and key techniques were analyzed, and the clinical efficacy was evaluated. RESULTS: Among 20 CRS patients, 14 were male and 6 were female with mean age of 59.9 years and mean BMI of 19.7 kg/m2. For the primary diseases, 17 patients underwent laparotomy, 3 underwent laparoscopic radical resection of gastric cancer; 18 cases received distal subtotal gastrectomy plus Billroth II( anastomosis, 2 received distal subtotal gastrectomy plus Billroth I( anastomosis. CRS located in anastomotic stoma in 15 cases and in the gastric fundus and cardiac part in 5 cases. Preoperative staging revealed 2 cases of T2NxM0, 1 of T3NxM0, 2 of TxNxM0 and 15 of T4aNxM0. Sixteen patients received robotic surgery with Roux-en-Y reconstruction successfully, and 4 patients were converted to laparotomy for palliative total gastrectomy, including 1 case with diaphragm invasion, 1 case with transverse colon invasion, and 2 cases with tight adhesions. The mean surgery time was (255±35) minutes, mean blood loss was (230±50) ml, mean number of dissected lymph nodes was 19.5±3.0, mean recovery time to gastrointestinal function was (2.3±1.0) days, mean time to feeding was (2.3±1.0) days, and mean time to ambulatory activity was (2.5±0.5) days. Pathological examinations revealed 12 patients with poorly differentiated adenocarcinoma, 6 patients with moderately differentiated adenocarcinoma, and 2 patients with mucinous adenocarcinoma. Postoperative pTNM staging was identified as follows: stage I(B for 1 patient, stage II(A for 2 patients, stage II(B for 5 patients, stage III(A for 5 patients, stage III(B for 4 patients, and stage III(C for 3 patients. One patient died 2 weeks after operation due to multiple organ failure. One patient received another hemostasis operation due to hemorrhage of splenic artery and recovered postoperatively. Two patients experienced anastomotic leakage, 1 patient developed duodenal stump fistula and 1 patient experienced incision site infection postoperatively, and all of them recovered after conservative treatment. During 5-60 months follow-up, 10 cases died and 10 cases survived, including 1 case for 6 years. CONCLUSIONS: Robotic surgery for CRS is feasible with satisfactory short-term efficacy. However, the long-term efficacy requires further study.