A positive feedback loop between Periostin and TGFβ1 induces and maintains the stemness of hepatocellular carcinoma cells via AP-2α activation

Background

Liver cancer stem cells (LCSCs) play key roles in the metastasis, recurrence, and chemotherapeutic resistance of hepatocellular carcinoma (HCC). Our previous research showed that the POSTN gene is closely related to the malignant progression and poor prognosis of HCC. This study aimed to elucidate the role of POSTN in generating LCSCs and maintaining their stemness as well as the underlying mechanisms.

Methods

Human HCC tissues and matched adjacent normal tissues were obtained from 110 patients. Immunohistochemistry, western blotting (WB), and RT-PCR were performed to detect the expression of POSTN and stemness factors. The roles of transforming growth factor (TGF)-β1 and AP-2α in the POSTN-induced stemness transformation of HCC cells were explored in vitro and in vivo using LCSCs obtained by CD133⁺ cell sorting.

Results

The high expression of POSTN was correlated with the expression of various stemness factors, particularly CD133, in our HCC patient cohort and in TCGA and ICGC datasets. Knockdown of POSTN expression decreased the abilities of HCC cell lines to form tumours in xenograft mouse models. Knockdown of POSTN expression also suppressed cell viability and clone formation, invasion, and sphere formation abilities in vitro. Knockdown of AP-2α attenuated the generation of CD133⁺ LCSCs and their malignant behaviours, indicating that AP-2α was a critical factor that mediated the POSTN-induced stemness transformation and maintenance of HCC cells. The role of AP-2α was verified by using a specific αvβ3 antagonist, cilengitide, in vitro and in vivo. Activation of POSTN could release TGFβ1 from the extracellular matrix and initiated POSTN/TGFβ1 positive feedback signalling. Furthermore, we found that the combined use of cilengitide and lenvatinib suppressed the growth of HCC cells with high POSTN expression more effectively than the use of lenvatinib alone in the patient-derived xenograft (PDX) mouse model.

Conclusions

The POSTN/TGFβ1 positive feedback pathway regulates the expression of stemness factors and the malignant progression of HCC cells by regulating the transcriptional activation of AP-2α. This pathway may serve as a new target for targeted gene therapy in HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02011-8.

Organoids of liver diseases: From bench to bedside

Understanding the occurrence, development, and treatment of liver diseases is the main goal of hepatopathology research. Liver diseases are not only diverse but also highly heterogeneous among individuals. At present, research on liver diseases is conducted mainly through cell culture, animal models, pathological specimens, etc. However, these methods cannot fully reveal the pathogenic mechanism and therapeutic characteristics of individualized liver diseases. Recent advances in three-dimensional cell culture technology (organoid culture techniques) include pluripotent stem cells and adult stem cells that are cultured in vitro to form self-organizing properties, making it possible to achieve individualized liver disease research. This review provides a comprehensive overview of the development of liver organoids, the existing and potential applications of liver regenerative medicine, the pathogenesis of liver disease heterogeneity, and drug screening.

Diagnostic accuracy of three-dimensional CT reconstruction and cephalometry for lateral skull base tumors

OBJECTIVE

To explore the diagnostic accuracy of three-dimensional CT reconstruction and cephalometry in lateral skull base tumors.

PATIENTS AND METHODS

Fifty-eight patients with lateral skull base tumors were randomly divided into control group (n = 29, examined with conventional diagnostic technique) or study group (n = 29, examined with three-dimensional CT reconstruction and cephalometry). The diagnostic accuracy, tumor distribution and image characteristics were compared between both patient groups.

RESULTS

In control group, preoperative tumor diagnosis was consistent with intraoperative diagnosis in 20 patients, similar in 7 patients and discrepant in 2 patients. In study group, there were 24 consistent, 4 similar, and 1 discrepant diagnoses (p < 0.05 vs. control group). Frequency of individual tumor types, as revealed by either diagnostic method, was comparable. The images obtained with three-dimensional CT reconstruction were clearer, facilitating an accurate demonstration of the tumor, including tumor size and location.

CONCLUSIONS

Three-dimensional CT reconstruction and cephalometry provides accurate diagnosis of lateral skull base tumors, which is helpful for subsequent surgical treatment.

[Repair and functional reconstruction of severe electrical burns of wrist]

OBJECTIVE

To reduce amputation rate of severe electrical burn of wrist and to promote partial recovery of the injuried hand.

METHODS

From 1987 to 1999, 44 cases, with 55 limbs of severe electrical burn were classified into 4 types, according to criteria of Dr Shen Zuyao, and were all treated by primary adequate decompression, timely debridement, reconstruction of blood circulation in cases complicated with blood vessel injury, and skin flap grafting from chest, abdomen or inguinal area, followed by treatment of anti-coaggluation and anti-infection. Once the wound healed, auto- or allo-transplantation or transferring of tendons were performed to repair tendon defect, and auto-nerve or fetal nerve transplantation performed for nerve defect.

RESULTS

After the primary treatment of the 55 burned limbs, all limbs of type IV were amputated, and most of other 3 types survived. The function, including sensation and movement, of survived hands partially recovered.

CONCLUSION

Primary reconstruction of blood circulation, cover of wound with skin flap, and timely repair of sensation and motor function are very crucial approach to reduce amputation rate and to promote the survived hand function of severe electrical burns of wrists.

Transcriptional protein binding domains governing basal expression of the rat luteinizing hormone receptor gene

The functional importance of specific protein binding domains on transcription within the GC-rich 173-base pair promoter of the luteinizing hormone receptor gene was studied by mutagenesis and gel retardation analysis. Transcription was dependent on the presence of two Sp1 elements in the promoter domain of transfected expressing mouse Leydig tumor cells (mLTC) and nonexpressing Chinese hamster ovary cells. Mutation of two protein binding domains located downstream of the Sp1 elements (M1 and C-box) revealed tissue-specific regulation of promoter activity by each domain. Also, gel retardation studies indicated the presence of multiple trans factors that bind to the C-box and M1 domains. Removal of the AP-2 element from the C-box resulted in mLTC-specific transcriptional activation that may involve an M1/C-box interaction. In addition, competition by overlapping NF-1 and AP-2 elements was demonstrable in both the C-box and upstream R domain for separate trans factors that exhibit neutral or inhibitory functions, respectively. Competition between the inhibitory and neutral DNA binding factors within both upstream and promoter domains may be responsible for a mechanism that controls the on/off state of luteinizing hormone receptor gene expression in gonadal cells. These studies reveal a complex pattern of transcriptional regulation that may reflect targeted mechanisms for the control of luteinizing hormone receptor gene expression.

Structural organization of the rat luteinizing hormone (LH) receptor gene

The luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor gene was isolated from rat liver genomic libraries and spanned at least 75 kilobase pairs from nucleotide -2057 of the 5'-flanking region to the 3'-noncoding end. The structural configuration of the coding region of the LH receptor gene consists of 11 exons separated by 10 introns that are all located within the putative extracellular domain prior to the first transmembrane region. The 5'-noncoding region contains several potential TATA boxes and SP1 promoter binding sites, as well as six palindromic elements, potential intron/exon splice junctions, and two extended open reading frames in frame with the initiation codon. Primer extension studies indicate the presence of multiple transcriptional initiation sites. Truncated forms of the LH/hCG receptor conform to alternative splicing patterns that are consistent either with the deletion of complete exons or alternate acceptor sites within exons. All splice site junctions correspond to known donor and acceptor consensus sequences. Exons 2-8 approximate the regions of the 14 consecutive 20 amino acid repeated motifs present in the LH, thyrotropin-stimulating hormone, and follicle-stimulating hormone receptor cDNAs, with the exception of a six to eight amino acid shift in each motif. Exons 1, 9, 10, and 11, do not conform to this repetitive intronic motif. These exons, however, contain important structural elements including the conserved cysteines (exons 1, 9, 11), the soybean lectin motif (exon 9), the seven-transmembrane domain with cytoplasmic G protein coupling elements (exon 11), and three putative N-linked glycosylation sites (exon 10), consistent with preservation of significant functional domains within single exons. Exon 10 and the beginning of exon 11 along with the lectin motif are unique to the LH receptor and may be involved in specific association with the hormonal ligand. The homologous regions with other members of the glycoprotein receptor family encoded by exons 2-8, and the common amino acid motif that contains 3 conserved cysteines immediately prior to the first transmembrane region, may be involved in common hormonal interactions and in coupling functions, respectively.

[Effect of endothelin on the release of angiotensin II from rat cardiovascular system]

The existence of angiotensin II immunoreactive substance in rat cardiovascular system was demonstrated by RIA and immunohistochemistry techniques. In atrium, aorta and cultured rat aorta smooth muscle cells, angiotensin II content is 7.2 + 2.7 pg/mg protein, 152.4 + 59.2 pg/mg protein and 3.5 + 0.8 pg/2 x 10(5) cells respectively. Endothelin, a potent vasoconstricting polypeptide, can enhance the release of angiotensin II from cultured rat aorta and aortic smooth muscle cells significantly. The results suggest that endothelin may be involved in the regulation of local blood flow and vascular tone, and it may also implicate the pathogenesis of some cardiovascular diseases such as cardiohypertrophy and vascular hypertrophy.

[Significance of endothelin in shock pathogenesis]

Endothelin is a recently discovered bioactive peptide produced by vascular endothelial cells. By means of specific radioimmunoassay we found that plasma endothelin level in patients with late septic shock was significantly increased. And a typical shock model in healthy rats was reproduced by continuous infusion of endothelin (endothelin shock). Infusion of endothelin at a small dose to hemorrhagic shocked rats deteriorated the shock process and resulted in an irreversible development. From these results it is suggested that endothelin may be an endogenous injury-inducing factor, acting as one of the important humoral factors involved in shock pathogenesis.

[Distribution of substance K in the rat heart and its cardiovascular effects]

The present work was to investigate the distribution of Substance K (SK) in the rat heart and its cardiovascular effects. The content of SK-like immunoreactive material (SKLI), determined by using specific radioimmunoassay, was higher in the atrium (19.9 +/- 3.5 pmol/g tissue) than in the ventricle (4.1 +/- 0.8 pmol/g tissue). SKLI in the heart existed in the nerves fibers and its molecular form was identical with synthetic SK. There were high affinity binding sites of SK on the cardiohybricyte CP 8401: KD = 0.161 nmol/L, Bmax = 8.08 pmol/L. SK stimulated the release of ANF from the cardiohybricytes and from the isolated rat atria. Furthermore, SK injected intravenously induced a hypotensive effect in rats, and decreased left ventricle end systolic pressure (LVESP), +/- LVdp/dtmax, as well as slightly increased heart rate (HR). In isolated Langendorff perfusion heart of rat, SK increased HR, LVdp/dtmax, left ventricle peak systolic pressure (LVPSP) and perfusion pressure (PP). These effects of SK were inhibited by a tachykinin receptor antagonist, (D-Pro2, D-Trp7.9)-SP. These findings suggest that SK exist in the heart and might be able to bind with its specific binding sites on the cardiocytes, thus inducing the release of ANF from the atrium and regulating cardiovascular functions.

Seroprevalence of Legionella in Shanxi Province, China

Using an ELISA with bacterial sonicate antigens, the prevalence of antibodies to the antigens of 15 legionellae was determined in 319 healthy individuals residing in Taiyuan, China (Shanxi Province). Significant antibody levels were detected to 11 antigens. Confirming earlier studies, an association was noted between cigarette smoking and seroreactivity, however, none was observed between occupation, or sex and seroreactivity. When the response to specific antigens or antigenic "groups" was studied, an association with work site was apparent. These data suggested a higher rate of exposure to Philadelphia 1 type antigens at the Bureau of Mining dormitory and a nearby electric power plant, and to E-327F/NY-23 type antigens at the Shanxi Mining College and Shanxi Daily newspaper. Further studies will define the reservoirs and mechanisms of exposure.

A dynorphin peptide induces hypotension by stimulating the release of atrial natriuretic peptide from rat atrium

Intravenous injection of dynorphin A-(1-10) amide (Dyn, 81-324 nmol/kg) induced a dose-dependent hypotensive effect in the rat. This effect was antagonized by pretreatment with immunoglobulin G, purified from a specific antiserum raised against alpha-human atrial natriuretic peptide (anti-hANP-IgG), as well as by high doses of naloxone (2 or 10 mg/kg). In addition, a 12-fold increase in plasma level of atrial natriuretic peptide-like immunoreactivity (ANP-IR) was found following Dyn administration, which was accompanied by a significant decrease of atrial ANP-IR. These results suggest that the stimulated release of ANP-IR from the atrium may constitute one of the mechanisms for the depressor effect of dynorphin peptides.