p53 regulates cytoskeleton remodeling to suppress tumor progression

p53 Regulates Nuclear Architecture to Reduce Carcinogen Sensitivity and Mutagenic Potential

The p53 tumor suppressor is an indispensable regulator of DNA damage responses that accelerates carcinogenesis when mutated. In this report, we uncover a new mechanism by which p53 maintains genomic integrity in the absence of canonical DNA damage response activation. Specifically, loss of p53 dramatically alters chromatin structure at the nuclear periphery, allowing increased transmission of an environmental carcinogen, ultraviolet (UV) radiation, into the nucleus. Genome-wide mapping of UV-induced DNA lesions in p53-deficient primary cells reveals elevated lesion abundance in regions corresponding to locations of high mutation burden in malignant melanomas. These findings uncover a novel role of p53 in the suppression of mutations that contribute to cancer and highlight the critical influence of nuclear architecture in regulating sensitivity to carcinogens.

Loss of p53 function promotes DNA damage-induced formation of nuclear actin filaments

Tumor suppressor p53 plays a central role in response to DNA damage. DNA-damaging agents modulate nuclear actin dynamics, influencing cell behaviors; however, whether p53 affects the formation of nuclear actin filaments remains unclear. In this study, we found that p53 depletion promoted the formation of nuclear actin filaments in response to DNA-damaging agents, such as doxorubicin (DOXO) and etoposide (VP16). Even though the genetic probes used for the detection of nuclear actin filaments exerted a promotive effect on actin polymerization, the detected formation of nuclear actin filaments was highly dependent on both p53 depletion and DNA damage. Whilst active p53 is known to promote caspase-1 expression, the overexpression of caspase-1 reduced DNA damage-induced formation of nuclear actin filaments in p53-depleted cells. In contrast, co-treatment with DOXO and the pan-caspase inhibitor Q-VD-OPh or the caspase-1 inhibitor Z-YVAD-FMK induced the formation of nuclear actin filament formation even in cells bearing wild-type p53. These results suggest that the p53-caspase-1 axis suppresses DNA damage-induced formation of nuclear actin filaments. In addition, we found that the expression of nLifeact-GFP, the filamentous-actin-binding peptide Lifeact fused with the nuclear localization signal (NLS) and GFP, modulated the structure of nuclear actin filaments to be phalloidin-stainable in p53-depleted cells treated with the DNA-damaging agent, altering the chromatin structure and reducing the transcriptional activity. The level of phosphorylated H2AX (γH2AX), a marker of DNA damage, in these cells also reduced upon nLifeact-GFP expression, whilst details of the functional relationship between the formation of nLifeact-GFP-decorated nuclear actin filaments and DNA repair remained to be elucidated. Considering that the loss of p53 is associated with cancer progression, the results of this study raise a possibility that the artificial reinforcement of nuclear actin filaments by nLifeact-GFP may enhance the cytotoxic effect of DNA-damaging agents in aggressive cancer cells through a reduction in gene transcription.

Chorein sensitive microtubule organization in tumor cells

Background

The purpose of this study is to analyzed the involvement of chorein in microtubules organization of three types of malignant; rhabdomyosarcoma tumor cells (ZF), rhabdomyosarcoma cells (RH30), and rhabdomyosarcoma cells (RD). ZF are expressing high chorein levels. Previous studies revealed that chorein protein silencing in ZF tumor cells persuaded apoptotic response followed by cell death. In addition, in numerous malignant and non-malignant cells this protein regulates actin cytoskeleton structure and cellular signaling. However, the function of chorein protein in microtubular organization is yet to be established.

Methods

In a current research study, we analyzed the involvement of chorein in microtubules organization by using three types of malignant rhabdomyosarcoma cells. We have applied confocal laser-scanning microscopy to analyze microtubules structure and RT-PCR to examine cytoskeletal gene transcription.

Results

We report here that in rhabdomyosarcoma cells (RH30), chorein silencing induced disarrangement of microtubular network. This was documented by laser scanning microscopy and further quantified by FACS analysis. Interestingly and in agreement with previous reports, tubulin gene transcription in RH cells was unchanged upon silencing of chorein protein. Equally, confocal analysis showed minor disordered microtubules organization with evidently weakened staining in rhabdomyosarcoma cells (RD and ZF) after silencing of chorein protein.

Conclusion

These results disclose that chorein silencing induces considerable structural disorganization of tubulin network in RH30 human rhabdomyosarcoma tumor cells. Additional studies are now needed to establish the role of chorein in regulating cytoskeleton architecture in tumor cells.

Understanding disruption of the gut barrier during inflammation: Should we abandon traditional epithelial cell lines and switch to intestinal organoids?

Disruption of the intestinal epithelial barrier is a hallmark of mucosal inflammation. It increases exposure of the immune system to luminal microbes, triggering a perpetuating inflammatory response. For several decades, the inflammatory stimuli-induced breakdown of the human gut barrier was studied in vitro by using colon cancer derived epithelial cell lines. While providing a wealth of important data, these cell lines do not completely mimic the morphology and function of normal human intestinal epithelial cells (IEC) due to cancer-related chromosomal abnormalities and oncogenic mutations. The development of human intestinal organoids provided a physiologically-relevant experimental platform to study homeostatic regulation and disease-dependent dysfunctions of the intestinal epithelial barrier. There is need to align and integrate the emerging data obtained with intestinal organoids and classical studies that utilized colon cancer cell lines. This review discusses the utilization of human intestinal organoids to dissect the roles and mechanisms of gut barrier disruption during mucosal inflammation. We summarize available data generated with two major types of organoids derived from either intestinal crypts or induced pluripotent stem cells and compare them to the results of earlier studies with conventional cell lines. We identify research areas where the complementary use of colon cancer-derived cell lines and organoids advance our understanding of epithelial barrier dysfunctions in the inflamed gut and identify unique questions that could be addressed only by using the intestinal organoid platforms.

Integrins in human hepatocellular carcinoma tumorigenesis and therapy

ABSTRACT

Integrins are a family of transmembrane receptors that connect the extracellular matrix and actin skeleton, which mediate cell adhesion, migration, signal transduction, and gene transcription. As a bi-directional signaling molecule, integrins can modulate many aspects of tumorigenesis, including tumor growth, invasion, angiogenesis, metastasis, and therapeutic resistance. Therefore, integrins have a great potential as antitumor therapeutic targets. In this review, we summarize the recent reports of integrins in human hepatocellular carcinoma (HCC), focusing on the abnormal expression, activation, and signaling of integrins in cancer cells as well as their roles in other cells in the tumor microenvironment. We also discuss the regulation and functions of integrins in hepatitis B virus-related HCC. Finally, we update the clinical and preclinical studies of integrin-related drugs in the treatment of HCC.

DIAPH3 is a prognostic biomarker and inhibit colorectal cancer progression through maintaining EGFR degradation

BACKGROUND

Actin cytoskeleton is connected with the processes of cell proliferation and migration in colorectal cancer (CRC). However, it is unknown how to accomplish these adjustments in CRC by actin cytoskeleton genes (ACGs) and here we investigated the role of hub prognosis-related ACGs-Diaphanous-related formin 3 (DIAPH3) in CRC, as a potential, novel target.

METHODS

The ACGs gene set from the Kyoto Encyclopedia of Genes and Genomes (KEGG) was used to group CRC patients and select prognosis-related ACGs by univariate and multivariate Cox regression for constructing prognostic model. Next, we tested hub prognosis-related ACGs- DIAPH3 expression in CRC and clarified the role of DIAPH3 by shRNA constructs in KM12 and SW480. Activation of EGFR was analyzed by western blot and immunofluorescence.

RESULTS

The results showed that actin cytoskeleton function is a significant prognostic factor for CRC patients and related to clinicopathological characteristics such as T stage and lymph node metastasis. A prognostic model constructed by four prognosis-related ACGs has a moderate intensity to 1-year Survival (AUC = 0.71). And hub prognosis-related ACGs DIAPH3 is downregulated in CRC. Knockdown of DIAPH3 could promote the proliferation and migration capacity of CRC. In addition, DIAPH3-silenced cells increase EGFR phosphorylation by inhibiting EGFR transportation to lysosome.

CONCLUSIONS

ACGs play a significant role in tumor invasion and have the potential to predict the prognosis of CRC. Prognosis-related ACGs DIAPH3 might be a new prognostic biomarker and DIAPH3 could inhibit CRC progression through maintaining EGFR degradation.

Synthesis of cinnamic acid ester derivatives with antiproliferative and antimetastatic activities on murine melanoma cells

Melanoma is the most aggressive skin cancer, and its incidence has continued to rise during the past decades. Conventional treatments present severe side effects in cancer patients, and melanoma can be refractory to commonly used anticancer drugs, which justify the efforts to find new potential anti-melanoma drugs. An alternative to promote the discovery of new pharmacological substances would be modifying chemical groups from a bioactive compound. Here we describe the synthesis of seventeen compounds derived from cinnamic acid and their bioactivity evaluation against melanoma cells. The compound phenyl 2,3-dibromo-3-phenylpropanoate (3q) was the most effective against murine B16-F10 cells, as observed in cytotoxicity and cell migration assays. Simultaneously, this compound showed low cytotoxic activity on non-tumor cells. At the highest concentration, the compound 3q was able to trigger apoptosis, whereas, at lower concentrations, it affected the cell cycle and melanoma cell proliferation. Furthermore, cinnamate 3q impaired cell invasion, adhesion, colonization, and actin polymerization. In conclusion, these results highlight the antiproliferative and antimetastatic potential of cinnamic acid derivatives on melanoma.

Cell and Tissue Nanomechanics: From Early Development to Carcinogenesis

Cell and tissue nanomechanics, being inspired by progress in high-resolution physical mapping, has recently burst into biomedical research, discovering not only new characteristics of normal and diseased tissues, but also unveiling previously unknown mechanisms of pathological processes. Some parallels can be drawn between early development and carcinogenesis. Early embryogenesis, up to the blastocyst stage, requires a soft microenvironment and internal mechanical signals induced by the contractility of the cortical actomyosin cytoskeleton, stimulating quick cell divisions. During further development from the blastocyst implantation to placenta formation, decidua stiffness is increased ten-fold when compared to non-pregnant endometrium. Organogenesis is mediated by mechanosignaling inspired by intercellular junction formation with the involvement of mechanotransduction from the extracellular matrix (ECM). Carcinogenesis dramatically changes the mechanical properties of cells and their microenvironment, generally reproducing the structural properties and molecular organization of embryonic tissues, but with a higher stiffness of the ECM and higher cellular softness and fluidity. These changes are associated with the complete rearrangement of the entire tissue skeleton involving the ECM, cytoskeleton, and the nuclear scaffold, all integrated with each other in a joint network. The important changes occur in the cancer stem-cell niche responsible for tumor promotion and metastatic growth. We expect that the promising concept based on the natural selection of cancer cells fixing the most invasive phenotypes and genotypes by reciprocal regulation through ECM-mediated nanomechanical feedback loop can be exploited to create new therapeutic strategies for cancer treatment.

Published anti-SARS-CoV-2 in vitro hits share common mechanisms of action that synergize with antivirals

The global efforts in the past year have led to the discovery of nearly 200 drug repurposing candidates for COVID-19. Gaining more insights into their mechanisms of action could facilitate a better understanding of infection and the development of therapeutics. Leveraging large-scale drug-induced gene expression profiles, we found 36% of the active compounds regulate genes related to cholesterol homeostasis and microtubule cytoskeleton organization. Following bioinformatics analyses revealed that the expression of these genes is associated with COVID-19 patient severity and has predictive power on anti-SARS-CoV-2 efficacy in vitro. Monensin, a top new compound that regulates these genes, was further confirmed as an inhibitor of SARS-CoV-2 replication in Vero-E6 cells. Interestingly, drugs co-targeting cholesterol homeostasis and microtubule cytoskeleton organization processes more likely present a synergistic effect with antivirals. Therefore, potential therapeutics could be centered around combinations of targeting these processes and viral proteins.

Combined histopathological risk score using TP53 protein expression, CD8+ T cell density and intratumoral budding is an independent predictor of neoadjuvant therapy response in rectal adenocarcinoma

AIMS

Neoadjuvant therapy is the recommended treatment for locally advanced rectal adenocarcinoma; however, there remains significant variability in response to therapy. Tumour protein 53 (TP53) has been associated with therapy response and prognosis with conflicting data. Recently, we demonstrated that immune cell density and intratumoral budding (ITB) are predictive factors in rectal cancer. We investigated the predictive value of TP53 immunohistochemistry with CD8⁺ T cell density and ITB on pretreatment biopsies of rectal adenocarcinoma for response to neoadjuvant therapy.

METHODS AND RESULTS

Pretreatment biopsies of rectal adenocarcinoma from 117 patients with neoadjuvant therapy were analysed for TP53 expression by immunohistochemistry, ITB, CD8⁺ T cell density and mismatch repair protein (MMR) status. Most rectal adenocarcinomas displayed aberrant TP53 expression (86 of 117, 74%). Compared to wild-type TP53, aberrant TP53 expression was associated with proficient MMR status (P = 0.003) and low CD8⁺ T cell density (P = 0.001). Aberrant TP53 was significantly associated with a partial to poor response to neoadjuvant therapy [odds ratio (OR) = 2.42, 95% confidence interval (CI) = 1.04-5.62, P = 0.04]. A combined histopathological risk score (HRS) was created using CD8⁺ T cell density, ITB and TP53 expression. Patients were separated into low (none to one factor) and high (two to three factors) HRS categories. In the multivariable model, patients with a high HRS were 3.25-fold more likely to have a partial or poor response to neoadjuvant therapy (95% CI = 1.48-7.11, P = 0.003).

CONCLUSIONS

Our study demonstrates that aberrant TP53 expression, high ITB and low CD8⁺ T cell density in pretreatment biopsies can help predict response to neoadjuvant therapy. These biomarkers may be helpful in identifying patients at risk for therapy resistance.

The Significant Role of the Microfilament System in Tumors

Actin is the structural protein of microfilaments, and it usually exists in two forms: monomer and polymer. Among them, monomer actin is a spherical molecule composed of a polypeptide chain, also known as spherical actin. The function of actin polymers is to produce actin filaments, so it is also called fibroactin. The actin cytoskeleton is considered to be an important subcellular filament system. It interacts with numerous relevant proteins and regulatory cells, regulating basic functions, from cell division and muscle contraction to cell movement and ensuring tissue integrity. The dynamic reorganization of the actin cytoskeleton has immense influence on the progression and metastasis of cancer as well. This paper explores the significance of the microfilament network, the dynamic changes of its structure and function in the presence of a tumor, the formation process around the actin system, and the relevant proteins that may be target molecules for anticancer drugs so as to provide support and reference for interlinked cancer treatment research in the future.

Myosin Motors: Novel Regulators and Therapeutic Targets in Colorectal Cancer

Colorectal cancer (CRC) remains the third most common cause of cancer and the second most common cause of cancer deaths worldwide. Clinicians are largely faced with advanced and metastatic disease for which few interventions are available. One poorly understood aspect of CRC involves altered organization of the actin cytoskeleton, especially at the metastatic stage of the disease. Myosin motors are crucial regulators of actin cytoskeletal architecture and remodeling. They act as mechanosensors of the tumor environments and control key cellular processes linked to oncogenesis, including cell division, extracellular matrix adhesion and tissue invasion. Different myosins play either oncogenic or tumor suppressor roles in breast, lung and prostate cancer; however, little is known about their functions in CRC. This review focuses on the functional roles of myosins in colon cancer development. We discuss the most studied class of myosins, class II (conventional) myosins, as well as several classes (I, V, VI, X and XVIII) of unconventional myosins that have been linked to CRC development. Altered expression and mutations of these motors in clinical tumor samples and their roles in CRC growth and metastasis are described. We also evaluate the potential of using small molecular modulators of myosin activity to develop novel anticancer therapies.

Intratumoral budding and automated CD8-positive T-cell density in pretreatment biopsies can predict response to neoadjuvant therapy in rectal adenocarcinoma

Tumor budding and CD8-positive (+) T-cells are recognized as prognostic factors in colorectal adenocarcinoma. We assessed CD8+ T-cell density and intratumoral budding in pretreatment rectal cancer biopsies to determine if they are predictive biomarkers for response to neoadjuvant therapy and survival. Pretreatment biopsies of locally advanced rectal adenocarcinoma from 117 patients were evaluated for CD8+ T-cell density using automated quantitative digital image analysis and for intratumoral budding and correlated with clinicopathological variables on postneoadjuvant surgical resection specimens, response to neoadjuvant therapy, and survival. Patients with high CD8+ T-cell density (≥157 per mm²) on biopsy were significantly more likely to exhibit complete/near complete response to neoadjuvant therapy (66% vs. 33%, p = 0.001) and low tumor stage (0 or I) on resection (62% vs. 30%, p = 0.001) compared with patients with low CD8+ T-cell density. High CD8+ T-cell density was an independent predictor of response to neoadjuvant therapy with a 2.63 higher likelihood of complete response (95% CI 1.04-6.65, p = 0.04) and a 3.66 higher likelihood of complete/near complete response (95% CI 1.60-8.38, p = 0.002). The presence of intratumoral budding on biopsy was significantly associated with a reduced likelihood of achieving complete/near complete response to neoadjuvant therapy (odds ratio 0.36, 95% CI 0.13-0.97, p = 0.048). Patients with intratumoral budding on biopsy had a significantly reduced disease-free survival compared with patients without intratumoral budding (5-year survival 39% vs 87%, p < 0.001). In the multivariable model, the presence of intratumoral budding on biopsy was associated with a 3.35-fold increased risk of tumor recurrence (95% CI 1.25-8.99, p = 0.02). In conclusion, CD8+ T-cell density and intratumoral budding in pretreatment biopsies of rectal adenocarcinoma are independent predictive biomarkers of response to neoadjuvant therapy and intratumoral budding associates with patient survival. These biomarkers may be helpful in selecting patients who will respond to neoadjuvant therapy and identifying patients at risk for recurrence.

Mutant TP53 interacts with BCAR1 to contribute to cancer cell invasion

BACKGROUND

Mutant TP53 interacts with other proteins to produce gain-of-function properties that contribute to cancer metastasis. However, the underlying mechanisms are still not fully understood.

METHODS

Using immunoprecipitation and proximity ligation assays, we evaluated breast cancer anti-estrogen resistance 1 (BCAR1) as a novel binding partner of TP53R273H, a TP53 mutant frequently found in human cancers. The biological functions of their binding were examined by the transwell invasion assay. Clinical outcome of patients was analysed based on TP53 status and BCAR1 expression using public database.

RESULTS

We discovered a novel interaction between TP53R273H and BCAR1. We found that BCAR1 translocates from the cytoplasm into the nucleus and binds to TP53R273H in a manner dependent on SRC family kinases (SFKs), which are known to enhance metastasis. The expression of full-length TP53R273H, but not the BCAR1 binding-deficient mutant TP53R273HΔ102-207, promoted cancer cell invasion. Furthermore, among the patients with mutant TP53, high BCAR1 expression was associated with a poorer prognosis.

CONCLUSIONS

The interaction between TP53R273H and BCAR1 plays an important role in enhancing cancer cell invasion. Thus, our study suggests a disruption of the TP53R273H-BCAR1 binding as a potential therapeutic approach for TP53R273H-harbouring cancer patients.

Human papillomavirus type 38 alters wild-type p53 activity to promote cell proliferation via the downregulation of integrin alpha 1 expression

Tumor suppressors can exert pro-proliferation functions in specific contexts. In the beta human papillomavirus type 38 (HPV38) experimental model, the viral proteins E6 and E7 promote accumulation of a wild-type (WT) p53 form in human keratinocytes (HKs), promoting cellular proliferation. Inactivation of p53 by different means strongly decreases the proliferation of HPV38 E6/E7 HKs. This p53 form is phosphorylated at S392 by the double-stranded RNA-dependent protein kinase PKR, which is highly activated by HPV38. PKR-mediated S392 p53 phosphorylation promotes the formation of a p53/DNMT1 complex, which inhibits expression of integrin alpha 1 (ITGA1), a repressor of epidermal growth factor receptor (EGFR) signaling. Ectopic expression of ITGA1 in HPV38 E6/E7 HKs promotes EGFR degradation, inhibition of cellular proliferation, and cellular death. Itga1 expression was also inhibited in the skin of HPV38 transgenic mice that have an elevated susceptibility to UV-induced skin carcinogenesis. In summary, these findings reveal the existence of a specific WT p53 form that displays pro-proliferation properties.

Persistence of a regeneration-associated, transitional alveolar epithelial cell state in pulmonary fibrosis

Stem cells undergo dynamic changes in response to injury to regenerate lost cells. However, the identity of transitional states and the mechanisms that drive their trajectories remain understudied. Using lung organoids, multiple in vivo repair models, single-cell transcriptomics and lineage tracing, we find that alveolar type-2 epithelial cells undergoing differentiation into type-1 cells acquire pre-alveolar type-1 transitional cell state (PATS) en route to terminal maturation. Transitional cells undergo extensive stretching during differentiation, making them vulnerable to DNA damage. Cells in the PATS show an enrichment of TP53, TGFβ, DNA-damage-response signalling and cellular senescence. Gain and loss of function as well as genomic binding assays revealed a direct transcriptional control of PATS by TP53 signalling. Notably, accumulation of PATS-like cells in human fibrotic lungs was observed, suggesting persistence of the transitional state in fibrosis. Our study thus implicates a transient state associated with senescence in normal epithelial tissue repair and its abnormal persistence in disease conditions.

Gut commensal derived-valeric acid protects against radiation injuries

BACKGROUND

Hematopoietic and intestinal systems side effects are frequently found in patients who suffered from accidental or medical radiation exposure. In this case, we investigated the effects of gut microbiota produced-valeric acid (VA) on radiation-induced injuries.

METHODS

Mice were exposed to total body irradiation (TBI) or total abdominal irradiation (TAI) to mimic accidental or clinical scenarios. High-performance liquid chromatography (HPLC) was performed to assess short-chain fatty acids (SCFAs) in fecal pellets. Oral gavage with VA was used to mitigate radiation-induced toxicity. Gross examination was performed to assess tissue injuries of thymus, spleen and small intestine. High-throughput sequencing was used to characterize the gut microbiota profile. Isobaric tags for relative and absolute quantitation (iTRAQ) were performed to analyze the difference of protein profile. Hydrodynamic-based gene delivery assay was performed to silence KRT1 in vivo.

RESULTS

VA exerted the most significant radioprotection among the SCFAs. In detail, VA replenishment elevated the survival rate of irradiated mice, protected hematogenic organs, improved gastrointestinal (GI) tract function and intestinal epithelial integrity in irradiated mice. High-throughput sequencing and iTRAQ showed that oral gavage of VA restored the enteric bacteria taxonomic proportions, reprogrammed the small intestinal protein profile of mice following TAI exposure. Importantly, keratin 1 (KRT1) played a pivotal role in the radioprotection of VA.

CONCLUSIONS

Our findings provide new insights into gut microbiota-produced VA and underpin that VA might be employed as a therapeutic option to mitigate radiation injury in pre-clinical settings.

ZNF185 is a p53 target gene following DNA damage

The transcription factor p53 is a key player in the tumour suppressive DNA damage response and a growing number of target genes involved in these pathways has been identified. p53 has been shown to be implicated in controlling cell motility and its mutant form enhances metastasis by loss of cell directionality, but the p53 role in this context has not yet being investigated. Here, we report that ZNF185, an actin cytoskeleton-associated protein from LIM-family of Zn-finger proteins, is induced following DNA-damage. ChIP-seq analysis, chromatin crosslinking immune-precipitation experiments and luciferase assays demonstrate that ZNF185 is a bona fide p53 target gene. Upon genotoxic stress, caused by DNA-damaging drug etoposide and UVB irradiation, ZNF185 expression is up-regulated and in etoposide-treated cells, ZNF185 depletion does not affect cell proliferation and apoptosis, but interferes with actin cytoskeleton remodelling and cell polarization. Bioinformatic analysis of different types of epithelial cancers from both TCGA and GTEx databases showed a significant decrease in ZNF185 mRNA level compared to normal tissues. These findings are confirmed by tissue micro-array IHC staining. Our data highlight the involvement of ZNF185 and cytoskeleton changes in p53-mediated cellular response to genotoxic stress and indicate ZNF185 as potential biomarker for epithelial cancer diagnosis.

Guanylate binding protein 1 (GBP-1) promotes cell motility and invasiveness of lung adenocarcinoma

Previously, we identified molecules involved in human invasive lung adenocarcinoma, and guanylate-binding protein 1 (GBP-1) was selected for further analysis. RT-PCR of normal lung and invasive lung adenocarcinoma tissue samples showed that the relative GBP-1 expression levels normalized to GAPDH for invasive lung adenocarcinoma were three-fold higher than those for normal lung samples (P < 0.05). GBP-1 gene and protein expression levels were also higher in mesenchymal-like than in epithelial-like lung adenocarcinoma cell lines. To determine whether GBP-1 participates in lung adenocarcinoma invasion, we performed migration and wound healing assays using RERF-LC-OK cells transfected with various siRNAs. The relative migration of transfected GBP1-siRNA1 and GBP1-siRNA2 cells was significantly lower than that of transfected control-siRNA cells. The relative wound healing capacities 6 and 12 h after cells transfected with GBP1-siRNA1 and GBP1-siRNA2 were scratched were significantly lower than those of the control-siRNA cells. Immunohistochemistry of 80 patients with Stage I lung adenocarcinoma revealed that non-invasive cells were GBP-1 negative in all cases. Invasive cells were GBP-1 positive in 10 cases (12.5%) and GBP-1 negative in 70 cases (87.5%). Lymphatic-vascular invasion was positive in 20 patients (25%) and positively correlated with GBP-1 expression (P < 0.05). In conclusion, GBP-1 may enhance lung adenocarcinoma invasiveness by promoting cell motility, and control of GBP-1 expression has the potential to contribute to the development of new therapeutic strategies for lung adenocarcinoma.

Biomarkers of basal cell carcinoma resistance to methyl-aminolevulinate photodynamic therapy

Background

Methyl-aminolevulinate photodynamic therapy (MAL-PDT) is an excellent option for the treatment of basal cell carcinoma (BCC). However, up to 25% of cases are resistant to this treatment modality.

Objective

The aim of this study was to identify potential biomarkers of BCC response to MAL-PDT.

Material and methods

Clinical, histological, and immunohistochemical (p53, Ki-67, CD-31, COX2, β-catenin, EGFR, and survivin) variables were analyzed in a retrospective study of consecutive BCC patients treated with MAL-PDT at the San Jorge Hospital, Huesca, Spain between January 2006 and December 2015. To deepen on these markers, the effects on p53 and cyclin D1 expression, in vitro response to MAL-PDT of 2 murine BCC cell lines (ASZ and BSZ), was also evaluated.

Results

The retrospective study examined the response to MAL-PDT of 390 BCCs from 182 patients. The overall clinical response rate was 82.8%, with a mean follow-up time of 35.96 months (SD = 23.46). Immunohistochemistry revealed positive p53 in 84.6% of responders but only 15.4% of nonresponsive tumors (p = 0.011). Tumors with increased peripheral palisading of basal cell islands to immunostaining β-catenin responded poorly to PDT (p = 0.01). In line with our findings in patients, in vitro studies revealed a better response to PDT in the p53-positive ASZ cell line than the p53-negative BSZ cell line (p<0.01).

Multivariate analysis revealed that the following variables were significantly associated with response to PDT: age, nBCC, presence of peritumoral inflammatory infiltrate, and p53 immunopositivity. Patients with positive p53 immunostaining were 68.54 times more likely to achieve cure than p53-negative patients (CI95% 2.94–159.8)

Conclusion

Our finding suggest that certain clinicopathological and immunohistochemical variables, particularly p53 expression, may serve as indicators of BCC response to MAL-PDT, and thus facilitate the selection of patients who are most likely to benefit from this therapy.

Characterisation of resistance mechanisms developed by basal cell carcinoma cells in response to repeated cycles of Photodynamic Therapy

Photodynamic Therapy (PDT) with methyl-aminolevulinate acid (MAL-PDT) is being used for the treatment of Basal cell carcinoma (BCC), but recurrences have been reported. In this work, we have evaluated resistance mechanisms to MAL-PDT developed by three BCC cell lines (ASZ, BSZ and CSZ), derived from mice on a ptch+/- background and with or without p53 expression, subjected to 10 cycles of PDT (10thG). The resistant populations showed mesenchymal-like structure and diminished proliferative capacity and size compared to the parental (P) cells. The resistance was dependent on the production of the endogenous photosensitiser protoporphyrin IX in the CSZ cell line and on its cellular localisation in ASZ and BSZ cells. Moreover, resistant cells expressing the p53 gene presented lower proliferation rate and increased expression levels of N-cadherin and Gsk3β (a component of the Wnt/β-catenin pathway) than P cells. In contrast, 10thG cells lacking the p53 gene showed lower levels of expression of Gsk3β in the cytoplasm and of E-cadherin and β-catenin in the membrane. In addition, resistant cells presented higher tumorigenic ability in immunosuppressed mice. Altogether, these results shed light on resistance mechanisms of BCC to PDT and may help to improve the use of this therapeutic approach.

Diverse and cancer type‑specific roles of the p53 R248Q gain‑of‑function mutation in cancer migration and invasiveness

Gain‑of‑function (GOF) mutations in the TP53 gene lead to acquisition of new functions by the mutated tumor suppressor p53 protein. A number of the over‑represented 'hot spot' mutations, including the ones in codons 175, 248 or 273, convey GOF phenotypes. Such phenotypes may include resistance to chemotherapeutics or changes in motility and invasiveness. Whereas the prevalent notion is that the acquisition of the p53 GOF phenotype translates into poorer prognosis for the patient, the analysis of a human somatic p53 mutations dataset demonstrated earlier tumor onset, but decreased frequency and altered location of metastases in patients with the p53‑R248Q allele. Therefore, the GOF activities of p53‑R248Q and p53‑D281G were analyzed in triple negative breast cancer MDA‑MB‑231 and lung adenocarcinoma H1299 cell lines with regard to invasive and metastatic traits. The expression of p53‑D281G increased the motility and invasiveness of the lung cancer cells, but not those of the breast cancer cells. In contrast, the expression of p53‑R248Q decreased the motility and invasiveness of the breast and lung cancer cells in a p53 transactivation‑dependent manner. The intravenous xenotransplantation of MDA‑MB‑231 cells expressing p53‑R248Q into zebrafish embryos resulted in an alteration of the distribution of cancer cells in the body of the fish. In p53‑R248Q‑expressing H1299 cells a decrease in the expression of TCF8/ZEB1 and N‑cadherin was observed, suggesting partial mesenchymal‑to‑epithelial transition. In the two cell lines expressing p53‑R248Q a decrease was noted in the expression of myosin light chain 2, a protein involved in actomyosin‑based motility. To the best of our knowledge, the present study is one of only few reports demonstrating the mutated p53 GOF activity resulting in a decrease of a malignant trait in human cancer.

LncRNAs regulate the cytoskeleton and related Rho/ROCK signaling in cancer metastasis

Some of the key steps in cancer metastasis are the migration and invasion of tumor cells; these processes require rearrangement of the cytoskeleton. Actin filaments, microtubules, and intermediate filaments involved in the formation of cytoskeletal structures, such as stress fibers and pseudopodia, promote the invasion and metastasis of tumor cells. Therefore, it is important to explore the mechanisms underlying cytoskeletal regulation. The ras homolog family (Rho) and Rho-associated coiled-coil containing protein serine/threonine kinase (ROCK) signaling pathway is involved in the regulation of the cytoskeleton. Moreover, long noncoding RNAs (lncRNAs) have essential roles in tumor migration and guide gene regulation during cancer progression. LncRNAs can regulate the cytoskeleton directly or may influence the cytoskeleton via Rho/ROCK signaling during tumor migration. In this review, we focus on the regulatory association between lncRNAs and the cytoskeleton and discuss the pathways and mechanisms involved in the regulation of cancer metastasis.

The physical interaction of p53 and plakoglobin is necessary for their synergistic inhibition of migration and invasion

Plakoglobin (PG) is a paralog of β-catenin with similar adhesive, but contrasting signalling functions. Although β-catenin has well-known oncogenic function, PG generally acts as a tumor/metastasis suppressor by mechanisms that are just beginning to be deciphered. Previously, we showed that PG interacted with wild type (WT) and a number of mutant p53s, and that its tumor/metastasis suppressor activity may be mediated, at least partially, by this interaction. Here, carcinoma cell lines deficient in both p53 and PG (H1299), or expressing mutant p53 in the absence of PG (SCC9), were transfected with expression constructs encoding WT and different fragments and deletions of p53 and PG, individually or in pairs. Transfectants were characterized for their in vitro growth, migratory and invasive properties and for mapping the interacting domain of p53 and PG. We showed that when coexpressed, p53-WT and PG-WT cooperated to decrease growth, and acted synergistically to significantly reduce cell migration and invasion. The DNA-binding domain of p53 and C-terminal domain of PG mediated p53/PG interaction, and furthermore, the C-terminus of PG played a central role in the inhibition of invasion in association with p53.

Cofilin-mediated Neuronal Apoptosis via p53 Translocation and PLD1 Regulation

Amyloid β (Aβ) accumulation is an early event in the pathogenesis of Alzheimer’s disease (AD), leading to mitochondrial and synaptic dysfunction, tau accumulation, and eventual neuronal death. While the p53 apoptotic pathway has clearly been associated with Aβ deposits and neuronal apoptosis, the critical upstream factors contributing to p53 activation in AD are not well understood. We have previously shown that cofilin activation plays a pivotal role in Aβ-induced mitochondrial and synaptic dysfunction. In this study, we show that activated cofilin (S3A) preferentially forms a complex with p53 and promotes its mitochondrial and nuclear localization, resulting in transcription of p53-responsive genes and promotion of apoptosis. Conversely, reduction of endogenous cofilin by knockdown or genetic deficiency inhibits mitochondrial and nuclear translocation of p53 in cultured cells and in APP/PS1 mice. This cofilin-p53 pro-apoptotic pathway is subject to negative regulation by PLD1 thorough cofilin inactivation and inhibition of cofilin/p53 complex formation. Finally, activated cofilin is unable to induce apoptosis in cells genetically lacking p53. These findings taken together indicate that cofilin coopts and requires the nuclear and mitochondrial pro-apoptotic p53 program to induce and execute apoptosis, while PLD1 functions in a regulatory multi-brake capacity in this pathway.

Substrate Stiffness Influences Doxorubicin-Induced p53 Activation via ROCK2 Expression

The physical properties of the extracellular matrix (ECM), such as stiffness, are involved in the determination of the characteristics of cancer cells, including chemotherapy sensitivity. Resistance to chemotherapy is often linked to dysfunction of tumor suppressor p53; however, it remains elusive whether the ECM microenvironment interferes with p53 activation in cancer cells. Here, we show that, in MCF-7 breast cancer cells, extracellular stiffness influences p53 activation induced by the antitumor drug doxorubicin. Cell growth inhibition by doxorubicin was increased in response to ECM rigidity in a p53-dependent manner. The expression of Rho-associated coiled coil-containing protein kinase (ROCK) 2, which induces the activation of myosin II, was significantly higher when cells were cultured on stiffer ECM substrates. Knockdown of ROCK2 expression or pharmacological inhibition of ROCK decreased doxorubicin-induced p53 activation. Our results suggest that a soft ECM causes downregulation of ROCK2 expression, which drives resistance to chemotherapy by repressing p53 activation.

Colorectal carcinomas with submucosal invasion (pT1): analysis of histopathological and molecular factors predicting lymph node metastasis

Submucosally invasive colorectal carcinoma (pT1) has the potential to be cured by local excision. In US surgical intervention is reserved for tumors with high-grade morphology, lymphvascular invasion, and close/positive margin. In other countries, particularly Japan, surgical therapy is also recommended for mucinous tumors, tumors with >1000 μm of submucosal invasion, and those with high tumor budding. These histological features have not been well evaluated in a western cohort of pT1 carcinomas. In a cohort of 116 surgically resected pT1 colorectal carcinomas, high tumor budding (P<0.001), lymphatic invasion (P=0.003), depth of submucosal invasion >1000 μm (P=0.04), and high-grade morphology (P=0.04) were significantly associated with lymph node metastasis on univariate analysis. Mucinous differentiation, tumor location, tumor growth pattern, and size of invasive component were not significant. On multivariate analysis, only high tumor budding was associated with lymph node metastasis with an odds ratio of 4.3 (P=0.004). A subset of 48 tumors (22 node-positive and 26 node-negative) was analyzed for mutations in 50 oncogenes and tumor suppressors. No statistically significant molecular alterations in these 50 genes were associated with lymph node status. However, lymphatic invasion was associated with BRAF mutations (P=0.01). Furthermore, high tumor budding was associated with mutations in TP53 (P=0.03) and inversely associated with mutations in the mTOR pathway (PIK3CA and AKT, P=0.02). In conclusion, this study demonstrates the importance of identifying high tumor budding in pT1 carcinomas when considering additional surgical resection. Molecular alterations associated with adverse histological features are identified.

Functions of the Tumor Suppressors p53 and Rb in Actin Cytoskeleton Remodeling

Mechanical microenvironments, such as extracellular matrix stiffness and strain, have crucial roles in cancer progression. Cells sense their microenvironments with mechanosensing biomolecules, which is accompanied by the modulation of actin cytoskeleton structures, and the signals are subsequently transduced downstream as biochemical signals. The tumor suppressors p53 and retinoblastoma protein (Rb) are known to prevent cancer progression. The p53 and Rb signaling pathways are disrupted in many types of cancers. Here, we review recent findings about the roles of these tumor suppressors in the regulation of mechanosensing biomolecules and the actin cytoskeleton. We further discuss how dysfunction in the p53- and/or Rb-mediated mechanosignaling pathways is potentially involved in cancer progression. These pathways might provide good targets for developing anticancer therapies.