p53 amyloid formation leading to its loss of function: implications in cancer pathogenesis

The transcriptional regulator p53 has an essential role in tumor suppression. Almost 50% of human cancers are associated with the loss of p53 functions, where p53 often accumulates in the nucleus as well as in cytoplasm. Although it has been previously suggested that amyloid formation could be a cause of p53 loss-of-function in subset of tumors, the characterization of these amyloids and its structure-function relationship is not yet established. In the current study, we provide several evidences for the presence of p53 amyloid formation (in human and animal cancer tissues); along with its isolation from human cancer tissues and the biophysical characterization of these tissue-derived fibrils. Using amyloid seed of p53 fragment (P8, p53(250-257)), we show that p53 amyloid formation in cells not only leads to its functional inactivation but also transforms it into an oncoprotein. The in vitro studies further show that cancer-associated mutation destabilizes the fold of p53 core domain and also accelerates the aggregation and amyloid formation by this protein. Furthermore, we also show evidence of prion-like cell-to-cell transmission of different p53 amyloid species including full-length p53, which is induced by internalized P8 fibrils. The present study suggests that p53 amyloid formation could be one of the possible cause of p53 loss of function and therefore, inhibiting p53 amyloidogenesis could restore p53 tumor suppressor functions.

Cell Adhesion on Amyloid Fibrils Lacking Integrin Recognition Motif

Amyloids are highly ordered, cross-β-sheet-rich protein/peptide aggregates associated with both human diseases and native functions. Given the well established ability of amyloids in interacting with cell membranes, we hypothesize that amyloids can serve as universal cell-adhesive substrates. Here, we show that, similar to the extracellular matrix protein collagen, amyloids of various proteins/peptides support attachment and spreading of cells via robust stimulation of integrin expression and formation of integrin-based focal adhesions. Additionally, amyloid fibrils are also capable of immobilizing non-adherent red blood cells through charge-based interactions. Together, our results indicate that both active and passive mechanisms contribute to adhesion on amyloid fibrils. The present data may delineate the functional aspect of cell adhesion on amyloids by various organisms and its involvement in human diseases. Our results also raise the exciting possibility that cell adhesivity might be a generic property of amyloids.

MTA1-mediated transcriptional repression of SMAD7 in breast cancer cell lines

Metastasis is a complex process facilitated by the action of several genes. Metastasis associated 1 (MTA1) gene is one such gene which assists the process of metastasis by regulating several molecular targets. MTA1 acts as part of a nucleosome remodelling and histone deacetylation complex, which is involved in transcriptional regulation. Expression of MTA1 has been shown to be closely correlated with aggressiveness in several types of cancers, including breast cancer. In the present study we show that MTA1 regulates SMAD7, a component of Transforming growth factor beta (TGFbeta) signalling. TGFbeta signals are transduced to the nucleus by the Smad family of proteins, which includes Smad7, an inhibitory SMAD, which acts as a negative regulator of TGFbeta. On knockdown of MTA1, SMAD7 expression increases. Treating cells with a histone deacetylase inhibitor also increases SMAD7 expression. MTA1 is recruited to SMAD7 promoter region. SMAD7 inhibits activation of SMAD2 and SMAD3 and we show that the levels of these active SMAD proteins are decreased in cells expressing shRNA against MTA1. We further show that on MTA1 knockdown, the expression of downstream targets of SMAD7 is decreased. MTA1 thus appears to regulate a key inhibitor of TGFbeta signalling, SMAD7. By regulating molecules like SMAD7 MTA1 might assist the process of tumourigenesis and metastasis.

Fascin overexpression promotes neoplastic progression in oral squamous cell carcinoma

Background

Fascin is a globular actin cross-linking protein, which plays a major role in forming parallel actin bundles in cell protrusions and is found to be associated with tumor cell invasion and metastasis in various type of cancers including oral squamous cell carcinoma (OSCC). Previously, we have demonstrated that fascin regulates actin polymerization and thereby promotes cell motility in K8-depleted OSCC cells. In the present study we have investigated the role of fascin in tumor progression of OSCC.

Methods

To understand the role of fascin in OSCC development and/or progression, fascin was overexpressed along with vector control in OSCC derived cells AW13516. The phenotype was studied using wound healing, Boyden chamber, cell adhesion, Hanging drop, soft agar and tumorigenicity assays. Further, fascin expression was examined in human OSCC samples (N = 131) using immunohistochemistry and level of its expression was correlated with clinico-pathological parameters of the patients.

Results

Fascin overexpression in OSCC derived cells led to significant increase in cell migration, cell invasion and MMP-2 activity. In addition these cells demonstrated increased levels of phosphorylated AKT, ERK1/2 and JNK1/2. Our in vitro results were consistent with correlative studies of fascin expression with the clinico-pathological parameters of the OSCC patients. Fascin expression in OSCC showed statistically significant correlation with increased tumor stage (P = 0.041), increased lymph node metastasis (P = 0.001), less differentiation (P = 0.005), increased recurrence (P = 0.038) and shorter survival (P = 0.004) of the patients.

Conclusion

In conclusion, our results indicate that fascin promotes tumor progression and activates AKT and MAPK pathways in OSCC-derived cells. Further, our correlative studies of fascin expression in OSCC with clinico-pathological parameters of the patients indicate that fascin may prove to be useful in prognostication and treatment of OSCC.

Vγ9Vδ2 T (γδ) lymphocytes: a promising approach for immunotherapy of solid tumors

3064

Background: The Vγ9Vd2 T (γd) blood lymphocyte subset has a strong cytotoxic potential and can be selectively activated with chemically-synthesized, structural analogues of non-conventional antigens like BrHPP (IPH1101). Their proliferation requires low dose of Interleukin-2 (IL-2). Methods: We developed several in vitro and in vivo models to assess the immunotherapeutic potential of IPH1101-activated γd cells: - Direct cytotoxicity assays on patient-derived primary tumor cell lines - Extensive pharmacodynamics in the non human primate (NHP) - Small scale in vitro amplification assays for IPH1101-sensitive patient pre-selection Then, two Phase I clinical trials were performed in solid tumor patients: - Autologous cell therapy with ex vivo IPH1101- expanded γd cells (1, 4 or 8.109 cells) - Direct administration of IPH1101 (200 to 1800 mg/m2 i.v.) and low dose IL-2 (106 U/m2 s.c.). Results: In NHP, IPH1101 and low dose IL-2 induce early pro-inflammatory cytokine release and dose-dependent γd cell amplification in peripheral blood. In vitro, mRCC tumor cells are efficiently and selectively killed by autologous γd cells. In Phase I clinical trials, both ex vivo expanded γd cells and IPH1101 were well tolerated. - Cell therapy-related AEs included mainly gastrointestinal disorders, flu-like symptoms and hypotension. Six patients showed stabilized disease. Median duration of stabilization was 25.7 weeks. 2 pts treated with 4.109 or 8.109 cells showed substantial tumor shrinkage at the 14-week evaluation (-22% and -48%, respectively). - When IPH1101 was administered with low dose of IL-2, a significant increase of blood γd T cells was observed (up to 240 times the basal values) and in terms of clinical activity assessment, among the evaluable mRCC population (n=15), 8 patients presented disease stabilization for more than 35 weeks, including 6 for more than 51 weeks. Conclusions: For the first time, a specific γd immunotherapy was fully developed and led to Phase I clinical trials. It has been found well tolerated. Encouraging signs of disease stabilisation in mRCC patients suggest that γd may have a role in the treatment of cancers resistant to conventional therapies. A phase 2 is ongoing in mRCC patients.

No significant financial relationships to disclose.

An autologous Vγ9Vδ2 T lymphocytes cell therapy product generated by BrHPP (INNACELL Gamma Delta [IGD]) in metastatic renal cell carcinoma patients: Phase I clinical trial results

2550

Background: Vγ9Vδ2 (γδ) T lymphocytes, a peripheral blood lymphocyte subset, have shown to be directly cytotoxic against renal carcinoma cells. Lymphocytes γδ can be selectively expanded ex vivo with BrHPP (Phosphostim) and IL-2. We conducted a phase I trial, to define the dose limiting toxicities (DLT), characterize the safety profile, the pharmacodynamics and potential efficacy. Methods: Patients (pts), with progressive mRCC, PS of 0–1 and no organ dysfunction, were included. A one hour iv infusion of IGD was administered alone at cycle 1, and combined with low dose of sc IL-2 (2 MIU/m2 d1 to d7) in the 2 subsequent cycles (every 3 weeks). IGD dose was escalated from 1, up to 8 billions cells (bil). Results: 10 mRCC pts were treated in the study at 3 IGD dose levels: 1 patient at 1 bil, 6 pts at 4 bil, 3 pts at 8 bil. One patient experienced a grade (G)3 hypotension (4 bil, cycle 3), and one patient presented reversible signs of biological disseminated intravascular coagulation (8 bil, cycle 2) graded as a serious adverse event and fulfilling a DLT criteria. At all doses the treatment was well tolerated during the product alone infusion (cycle 1). The most frequent type of adverse events presented was mild to moderate flue like symptomes as fever, chills and asthenia reported during the second and third cycles in the IL-2 combined cycles. Patients presented also gastrointestinal symptoms as nausea and vomiting of grade 1 or 2. Preliminary efficacy assessment evaluation shows: 2 pts were not evaluable, 3 pts were withdrawn for disease progression at 3, 8 and 11 weeks, 2 pts maintained a stable disease for 36 and 63 weeks, and 2 pts are still under follow up with a stable disease at >91 and >124 weeks post treatment. Of note, one patient showed a 19% decrease in tumour size and another one presented a significant pain decrease leading to quality of life improvement. One other patient recently treated, is still under follow-up without progression after >16 weeks post treatment. Conclusion: IGD in combination with sc low dose IL-2 is safe, well tolerated, and shows promising antitumor signs of efficacy. These results warrant further product evaluation in phase 2 clinical trials.

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