Disruptin, a cell-penetrating peptide degrader of EGFR Mehta, Ranjit K.; Shukla, Sushmita; Ramanand, Susmita G. ...
Translational oncology,
August 2021, 2021-08-00, 2021-08-01, Letnik:
14, Številka:
8
Journal Article
Recenzirano
Odprti dostop
•Systemic injection of Disruptin is effective in small tumors but was minimally effective in animals with established tumors.Intratumoral injections of Disruptin reduced EGFR protein level and slowed ...tumor growth.•Disruptin peptide causes the disappearance of EGFR protein and also affect angiogenesis.•The Disruptin peptide was toxic when dosed systemically.•Overall, these findings suggest that an agent that can reduce EGFR protein could offer an alternate therapy for EGFR driven tumors.
Disruptin is a cell-permeable decoy peptide designed to destabilize activated EGFR, both by inhibiting Hsp90 chaperoning and dissociating the active asymmetric EGFR dimer, which leads to an increase in engagement of activated EGFR with the proteolytic degradation machinery and subsequent loss from the cells. Disruptin is an N-terminally biotinylated nonadecapeptide, with 8 amino acids from the αC-helix-β4 sheet loop of EGFR (S767-C774) fused to a TAT undecapeptide. The S767-R775 loop is at the interface with juxtamembrane domains in the active EGFR dimers and is a binding site for Hsp90. Cellular studies in EGFR-activated tumor cells demonstrated that Disruptin causes the disappearance of EGFR protein from cells over a few hours, a growth inhibitory effect, similar but more effective than the EGFR kinase inhibition. Interestingly, cells without activated EGFR remained unaffected. In vivo studies showed that Disruptin slowed the growth of small tumors. Larger tumors responded to intratumoral injections but did not respond to systemic administration at tolerated doses. Investigation of these results revealed that systemic administration of Disruptin has acute toxicities, mainly related to its TAT peptide moiety. Therefore, we conclude that although the efficacy of both in vitro and in vivo intratumoral injection of Disruptin supports the therapeutic strategy of blocking activated EGFR dimerization, Disruptin is not suitable for further development. These studies also highlight the importance of the chosen models and drug-delivery methods for such investigations.
Nuclear envelope morphology protein 1 (
NEM1
) along with a phosphatidate phosphatase (
PAH1
) regulates lipid homeostasis and membrane biogenesis in yeast and mammals. We investigated four putative
...NEM1
homologues (
TtNEM1A
,
TtNEM1B
,
TtNEM1C
and
TtNEM1D
) in the
Tetrahymena thermophila
genome. Disruption of
TtNEM1B
,
TtNEM1C
or
TtNEM1D
did not compromise normal cell growth. In contrast, we were unable to generate knockout strain of
TtNEM1A
under the same conditions, indicating that
TtNEM1A
is essential for
Tetrahymena
growth. Interestingly, loss of
TtNEM1B
but not
TtNEM1C
or
TtNEM1D
caused a reduction in lipid droplet number. Similar to yeast and mammals, TtNem1B of
Tetrahymena
exerts its function
via
Pah1, since we found that
PAH1
overexpression rescued loss of Nem1 function. However, unlike
NEM1
in other organisms,
TtNEM1B
does not regulate ER/nuclear morphology. Similarly, neither
TtNEM1C
nor
TtNEM1D
is required to maintain normal ER morphology. While
Tetrahymena PAH1
was shown to functionally replace yeast
PAH1
earlier, we observed that
Tetrahymena NEM1
homologues did not functionally replace yeast
NEM1
. Overall, our results suggest the presence of a conserved cascade for regulation of lipid homeostasis and membrane biogenesis in
Tetrahymena
. Our results also suggest a Nem1-independent function of Pah1 in the regulation of ER morphology in
Tetrahymena
.
Phosphatidate phosphatases (PAH) play a central role in lipid metabolism and intracellular signaling. Herein, we report the presence of a low-molecular-weight
PAH
homolog in the single-celled ciliate
...Tetrahymena thermophila
.
In vitro
phosphatase assay showed that TtPAH2 belongs to the magnesium-dependent phosphatidate phosphatase (PAP1) family. Loss of function of
TtPAH2
did not affect the growth of
Tetrahymena
. Unlike other known
PAH
homologs,
TtPAH2
did not regulate lipid droplet number and ER morphology.
TtPAH2
did not rescue growth and ER/nuclear membrane defects of the
pah1∆
yeast cells, suggesting that the phosphatidate phosphatase activity of the protein is not sufficient to perform these cellular functions. Surprisingly,
TtPAH2
complemented the respiratory defect in the
pah1∆
yeast cells indicating a specific role of
TtPAH2
in respiration. Overall, our results indicate that TtPAH2 possesses the minimal function of PAH protein family in respiration. We suggest that the amino acid sequences absent from TtPAH2 but present in all other known PAH homologs are critical for lipid homeostasis and membrane biogenesis.
Phosphatidic acid phosphatases are involved in the biosynthesis of phospholipids and triacylglycerol, and also act as transcriptional regulators. Studies to ascertain its role in lipid metabolism and ...membrane biogenesis are restricted only to Opisthokonta and Archaeplastida. Herein, we report the role of phosphatidate phosphatase (PAH) in Tetrahymena thermophila, belonging to the Alveolata clade. We identified two PAH homologs in Tetrahymena, TtPAH1, and TtPAH2. Loss of function of TtPAH1 results in reduced lipid droplet number and increase in ER content. It also shows more ER sheet structure as compared to wild type Tetrahymena. Surprisingly, we did not observe a visible defect in nuclear morphology of ΔTtpah1 mutant. TtPAH1 rescued all the known defects in yeast pah1Δ strain and is conserved functionally between Tetrahymena and yeast. The homologous gene derived from Trypanosoma also rescued the defects of yeast pah1Δ strain. Our results indicate that PAH, previously known to be conserved between Opisthokonts, is also present in a set of distant lineages. Thus, a phosphatase cascade is evolutionarily conserved and is functionally interchangeable across eukaryotic lineages.
•
Systemic injection of Disruptin is effective in small tumors but was minimally effective in animals with established tumors.
Intratumoral injections of Disruptin reduced EGFR protein level and ...slowed tumor growth.
•
Disruptin peptide causes the disappearance of EGFR protein and also affect angiogenesis.
•
The Disruptin peptide was toxic when dosed systemically.
•
Overall, these findings suggest that an agent that can reduce EGFR protein could offer an alternate therapy for EGFR driven tumors.
Disruptin is a cell-permeable decoy peptide designed to destabilize activated EGFR, both by inhibiting Hsp90 chaperoning and dissociating the active asymmetric EGFR dimer, which leads to an increase in engagement of activated EGFR with the proteolytic degradation machinery and subsequent loss from the cells. Disruptin is an N-terminally biotinylated nonadecapeptide, with 8 amino acids from the αC-helix-β4 sheet loop of EGFR (S
767
-C
774
) fused to a TAT undecapeptide. The S
767
-R
775
loop is at the interface with juxtamembrane domains in the active EGFR dimers and is a binding site for Hsp90. Cellular studies in EGFR-activated tumor cells demonstrated that Disruptin causes the disappearance of EGFR protein from cells over a few hours, a growth inhibitory effect, similar but more effective than the EGFR kinase inhibition. Interestingly, cells without activated EGFR remained unaffected.
In vivo
studies showed that Disruptin slowed the growth of small tumors. Larger tumors responded to intratumoral injections but did not respond to systemic administration at tolerated doses. Investigation of these results revealed that systemic administration of Disruptin has acute toxicities, mainly related to its TAT peptide moiety. Therefore, we conclude that although the efficacy of both
in vitro
and
in vivo
intratumoral injection of Disruptin supports the therapeutic strategy of blocking activated EGFR dimerization, Disruptin is not suitable for further development. These studies also highlight the importance of the chosen models and drug-delivery methods for such investigations.
Abstract Relativistic jets from accreting supermassive black holes at cosmological distances can be powerful emitters of γ -rays. However, the precise mechanisms and locations responsible for the ...dissipation of energy within these jets, leading to observable γ -ray radiation, remain elusive. We detect evidence for an intrinsic absorption feature in the γ -ray spectrum at energies exceeding 10 GeV, presumably due to the photon–photon pair production of γ -rays with low-ionization lines at the outer edge of broad-line region (BLR), during the high-flux state of the flat-spectrum radio quasar PKS 1424−418. The feature can be discriminated from the turnover at higher energies resulting from γ -ray absorption in the extragalactic background light. It is absent in the low-flux states, supporting the interpretation that powerful dissipation events within or at the edge of the BLR evolve into fainter γ -ray emitting zones outside the BLR, possibly associated with the moving very long baseline interferometry radio knots. The inferred location of the γ -ray emission zone is consistent with the observed variability timescale of the brightest flare, provided that the flare is attributed to external Compton scattering with BLR photons.
Background No data exist for the long-term outcome of metastatic colorectal cancer (mCRC) from the Southern part of Asia. The primary objective of the study is to evaluate the survival outcome of ...mCRC from an Indian tertiary care center. The study also aims to highlight the treatment pattern practiced and the unique clinico-pathologic characteristics. Methods This is a single-center retrospective observational study done at a large referral tertiary care center in North India. All patients with synchronous or metachronous mCRC who received at least one dose of chemotherapy for metastatic disease, registered between 2003 to 2017 were included. Primary outcome measures were overall survival and progression-free survival and prognostic factors of overall survival. Descriptive analysis was done for the clinicopathological characteristics and treatment patterns. Kaplan Meier method for overall survival and progression-free survival. Cox regression analysis was performed for the determination of the prognostic factors for overall survival. Result Out of 377 eligible patients, 256 patients (68%) had de novo metastatic disease and the remaining 121 (32%) progressed to metastatic disease after initial treatment. The cohort was young (median age, 46 years) with the most common primary site being the rectum. A higher proportion of signet (9%) and mucinous histology (24%). The three common sites of metastasis were the liver, peritoneum, and lung. In the first line, most patients received oxaliplatin-based chemotherapy (70%). Only 12.5% of patients received biologicals in the first-line setting. The median follow-up and median overall survival of study cohort were 17 months and 18.5 months. The factors associated with poor outcome for overall survival on multivariate analysis were ECOG performance status of > 1, high CEA, low albumin, and the number of lines of chemotherapy received (< 2). Conclusion The outcome of mCRC is inferior to the published literature. We found a relatively higher proportion of patients with the following characteristics; younger, rectum as primary tumor location, the signet, and mucinous histology, higher incidence of peritoneum involvement. The routine use of targeted therapies is limited. Government schemes (inclusion of targeted therapies in the Ayushman scheme), NGO assistance, and availability of generic low-cost targeted drugs may increase the availability. Keywords: Metastatic, Colorectal cancer, Real life experience, India
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Context.
Blazars, a class of active galaxies whose jets are relativistic and collimated flows of plasma directed along the line of sight, are prone to a slew of magnetohydrodynamic (MHD) ...instabilities. These jets show characteristic multi-wavelength and multi-timescale variabilities.
Aims.
We aim to study the interplay of radiation and particle acceleration processes in regulating the multi-band emission and variability signatures from blazars. In particular, the goal is to decipher the impact of shocks arising due to MHD instabilities in driving the long-term variable emission signatures from blazars.
Methods.
To this end, we performed relativistic MHD (RMHD) simulations of a representative section of a blazar jet. The jet was evolved using a hybrid Eulerian-Lagrangian framework to account for radiative losses due to synchrotron process as well as particle acceleration due to shocks. Additionally, we incorporated and validated radiative losses taking into consideration the external Compton (EC) process that is relevant for blazars. We further compared the effects of different radiation mechanisms through numerical simulation of 2D slab jet as a validation test. Finally, we carried out a parametric study to quantify the effect of magnetic fields and external radiation field characteristics by performing 3D simulations of a plasma column. The synthetic light curves and spectral energy distribution (SEDs) were analyzed to qualitatively understand the impact of instability driven shocks.
Results.
We observed that shocks produced with the evolution of instabilities give rise to flaring signatures in the high-energy band. The impact of such shocks is also evident from the instantaneous flattening of the synchrotron component of the SEDs. At later stages, we observed the transition in X-ray emission from the synchrotron process to that dominated by EC. The inclusion of the EC process also gives rise to
γ
-ray emission and shows signatures of mild Compton dominance that is typically seen in low-synchrotron peaked blazars.
To determine equivalence of modified gemcitabine and oxaliplatin compared with gemcitabine and cisplatin in unresectable gallbladder cancer (GBC). Primary end-point was overall survival (OS).
Open ...label, prospective, randomised phase III equivalence study. Inclusion criteria included histologically proven unresectable GBC, 18 years or older, adequate organ functions and Eastern Cooperative Oncology Group ≤2.
108 patients were required in each arm to have an equivalence margin of ±2 months with power of 80%.
Modified gemcitabine and oxaliplatin (mGemOx)—gemcitabine 900 mg/m2, oxaliplatin 80 mg/m2, maximum 6 cycles; gemcitabine + cisplatin (CisGem)—gemcitabine 1000 mg/m2, cisplatin 25 mg/m2, maximum 8 cycles, all day 1 and 8 every 3 weeks.
Two hundred sixty subjects were recruited between February 2011 and July 2015. Two hundred forty-three patients (119, mGemOx and 124, CisGem) received at least 1 dose and analysed for safety and efficacy (modified intention to treat). Median OS was 8·5 months for whole group (95% confidence interval CI: 7·9–9·1). Median OS in mGemOx was 9 months and 8·3 months in CisGem; p = 0·057 (hazard ratio = 0·78; 95% CI = 0·60-1·02). Restricted mean OS for follow-up limited to 30 months was 11·2 months (95% CI: 9·8–12·6) in mGemOx and 10·4 months (95% CI: 9·1–11·7) in CisGem. Difference of the mean was 0·8 months with 95% CI, exceeding 2 months (−1·1 to 2·7), hence rejecting equivalence. Peripheral neuropathy, thrombocytopaenia in mGemOx and nephrotoxicity was higher with CisGem.
This trial failed to show equivalence of eight cycles of CisGem to six cycles of mGemOx. Numerically OS was better with mGemOx. Toxicities were different. The trial was not powered to answer superiority.
CTRI/2010/091/001406.
•No randomised controlled trials have compared CisGem and mGemOx in unresectable gallbladder cancer.•A phase III randomised equivalence study with 2 months of equivalence margin was conducted.•243 subjects were analysed in modified ITT analysis.•Median overall survival in mGemOx was 9 months and 8·3 months in CisGem.•Results confirmed that 8 cycles of CisGem were not equivalent to 6 cycles of mGemOx.
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