Progesterone receptor potentiates macropinocytosis through CDC42 in pancreatic ductal adenocarcinoma.

Endocrine receptors play an essential role in tumor metabolic reprogramming and represent a promising therapeutic avenue in pancreatic ductal adenocarcinoma (PDAC). PDAC is characterized by a nutrient-deprived microenvironment. To meet their ascendant energy demands, cancer cells can internalize extracellular proteins via macropinocytosis. However, the roles of endocrine receptors in macropinocytosis are not clear. In this study, we found that progesterone receptor (PGR), a steroid-responsive nuclear receptor, is highly expressed in PDAC tissues obtained from both patients and transgenic LSL-KrasG12D/+; LSL-Trp53R172H/+; PDX1-cre (KPC) mice. Moreover, PGR knockdown restrained PDAC cell survival and tumor growth both in vitro and in vivo. Genetic and pharmacological PGR inhibition resulted in a marked attenuation of macropinocytosis in PDAC cells and subcutaneous tumor models, indicating the involvement of this receptor in macropinocytosis regulation. Mechanistically, PGR upregulated CDC42, a critical regulator in macropinocytosis, through PGR-mediated transcriptional activation. These data deepen the understanding of how the endocrine system influences tumor progression via a non-classical pathway and provide a novel therapeutic option for patients with PDAC.

[Effects and Mechanisms of Homoharringtonine on Expression of CEBPA Protein].

OBJECTIVE: To investigate the effect of homoharringtonine (HHT) on CEBPA protein and explore the mechanism of HHT in the treatment of acute myeloid leukemia (AML) with double CEBPA mutations. METHODS: The K562 cell line expressing CEBPA p30 (K562 CEBPA p30) was established. Western blot was used to determine the changes of the expression of CEBPA protein in K562 CEBPA p30, U937 and MOLM-13 cell lines before and after treatments with HHT, daunorubicin (DNR) or cytarabine (Ara-C). The effects of protease inhibitors and protein synthesis inhibitors on the expression of CEBPA protein were also determined. RNA-seq was used to analyze the difference of gene expressions and pathway enrichments between HHT group and DNR group. RESULTS: Both the endogenous CEBPA protein in U937 and MOLM-13 cell lines and the exogenous CEBPA protein in K562 CEBPA p30 were decreased by HHT (P<0.05) while were not by DNR or Ara-C. Proteasome inhibitors can increase the expression of CEBPA protein (P<0.05) while protein synthesis inhibitors can decrease the expression of CEBPA protein (P<0.05). The ribosome biogenesis related pathways in K562 CEBPA p30 were upregulated in HHT group while were not in DNR group. CONCLUSION: HHT can inhibit the synthesis of CEBPA and reduce the expression of CEBPA protein and this may be the mechanism of HHT in the treatment of CEBPA-double-mutant AML.

Identification of a potential hydrophobic peptide binding site in the C-terminal arm of trigger factor.

Trigger factor (TF) is the first chaperone to interact with nascent chains and facilitate their folding in bacteria. Escherichia coli TF is 432 residues in length and contains three domains with distinct structural and functional properties. The N-terminal domain of TF is important for ribosome binding, and the M-domain carries the PPIase activity. However, the function of the C-terminal domain remains unclear, and the residues or regions directly involved in substrate binding have not yet been identified. Here, a hydrophobic probe, bis-ANS, was used to characterize potential substrate-binding regions. Results showed that bis-ANS binds TF with a 1:1 stoichiometry and a K(d) of 16 microM, and it can be covalently incorporated into TF by UV-light irradiation. A single bis-ANS-labeled peptide was obtained by tryptic digestion and identified by MALDI-TOF mass spectrometry as Asn391-Lys392. In silico docking analysis identified a single potential binding site for bis-ANS on the TF molecule, which is adjacent to this dipeptide and lies in the pocket formed by the C-terminal arms. The bis-ANS-labeled TF completely lost the ability to assist GAPDH or lysozyme refolding and showed increased protection toward cleavage by alpha-chymotrypsin, suggesting blocking of hydrophobic residues. The C-terminal truncation mutant TF389 also showed no chaperone activity and could not bind bis-ANS. These results suggest that bis-ANS binding may mimic binding of a substrate peptide and that the C-terminal region of TF plays an important role in hydrophobic binding and chaperone function.

[Role of 16 slices spiral CT angiography with 3-dimensional CT and CT virtual endoscopy in detecting blood supply of lung carcinoma].

BACKGROUND & OBJECTIVE: Angiography, a common method in evaluating blood supply of lung carcinoma, is invasive and complicated, with low success rate for bronchial artery, and could not assure to show all supply blood vessels at a time. This study was to explore clinical value of 16 slices spiral CT angiography with 3-dimensional CT (3DCT) and CT virtual endoscopy (CTVE) in diagnosing and evaluating supply blood vessels and blood supply of lung carcinoma, so as to find a non-invasive, safe, simple and effective method in diagnosing blood supply of lung carcinoma. METHODS: A total of 72 patients with pathologically proved lung carcinoma underwent 16 slices spiral CT angiography with 3DCT. Volume rendering (VR), maximum intensity projection (MIP), and surface shaded display (SSD) of supply blood vessels of lung carcinoma were used as 3DCT models. CTVE of bronchial artery was performed in 25 patients. Color VR of tumor lesion was performed in all patients. RESULTS: Supply blood vessels were showed in 68 patients, 59 of them showed only bronchial artery, 5 showed intercostals arteries, and 4 showed mixed types, including bronchial artery, intercostals arteries, or branch arteries of subclavian artery. The bronchial artery entered into enlarged mediastinal lymph nodes in 4 patients. CTVE well displayed the orifice and lumen of bronchial arteries in the 25 patients. The extent of red color of tumor lesion on VR color image were divided into 4 types: no color (n=11), light red (n=17), moderate red (n=32), and heavy red (n=12); the added CT values of tumor lesion after enhanced CT were (6.16+/-2.23) Hu, (15.71+/-3.13) Hu, (25.47+/-2.71) Hu, and (44.31+/-19.68) Hu, respectively. The corresponding rate between enhanced type and distributive type of red color on color VR was 86.1%. CONCLUSIONS: The 16 slices spiral CT angiography with 3DCT and CTVE could show clearly supply blood vessels and blood supply of lung carcinoma. It is a non-invasive, simple and effective method in evaluating and diagnosing blood supply of lung carcinoma.

[The value of three-phase pulmonary helical CT in diagnosing peripheral pulmonary cancer (diameter

OBJECTIVE: To evaluate the value of three-phase pulmonary helical CT in diagnosing peripheral pulmonary cancer (diameter

[Helical dual-phase CT scan in evaluating blood supply of primary heptocellular carcinoma after transcatheter hepatic artery chemoembolization with lipiodol].

OBJECTIVE: To evaluate the blood supply of low density viable area of primary heptocellular carcinoma after transcatheter hepatic artery chemoembolization using lipiodol (LP-TACE), by helical dual-phase CT scanning and three dimensional CT (3DCT). METHODS: Thirty-four patients with primary heptocellular carcinoma after LP-TACE were examined by hepatic helical dual-phase CT. 3DCT model of the maximum intensity projection (MIP), surface shaded display (SSD) reconstruction of the hepatic artery and portal vein were simultaneously done in 5 cases. RESULTS: Viable tumor areas of 34 cases of primary heptocellular carcinoma after LP-TACE were divided into four types: peripheral, lateral, central and diffused types. Enhanced tumor vessel or tissue in viable tumor area was found during hepatic dual-phase in 17 cases, during hepatic artery-phase only in 8 and hepatic portal vein-phase only in 3. The viable tumor areas were found to have blood supply from the hepatic vein in 2 cases. The viable tumor area unenhanced during hepatic dual-phase was found in 6 cases. In 5 cases, the relation between the viable tumor area and branches of hepatic artery and portal vein was showed by MIP and SSD of hepatic artery and portal vein. CONCLUSION: Hepatic helical dual-phase CT scan with 3DCT is effective in evaluating the blood supply of viable tumor areas and the therapeutic effect of primary heptocellular carcinoma after LP-TACE.