High Expression of SQSTM1/p62 Protein Is Associated with Poor Prognosis in Epithelial Ovarian Cancer

Tumor biomarkers for diagnosis, prognosis and targeted therapy

Tumor biomarkers, the substances which are produced by tumors or the body's responses to tumors during tumorigenesis and progression, have been demonstrated to possess critical and encouraging value in screening and early diagnosis, prognosis prediction, recurrence detection, and therapeutic efficacy monitoring of cancers. Over the past decades, continuous progress has been made in exploring and discovering novel, sensitive, specific, and accurate tumor biomarkers, which has significantly promoted personalized medicine and improved the outcomes of cancer patients, especially advances in molecular biology technologies developed for the detection of tumor biomarkers. Herein, we summarize the discovery and development of tumor biomarkers, including the history of tumor biomarkers, the conventional and innovative technologies used for biomarker discovery and detection, the classification of tumor biomarkers based on tissue origins, and the application of tumor biomarkers in clinical cancer management. In particular, we highlight the recent advancements in biomarker-based anticancer-targeted therapies which are emerging as breakthroughs and promising cancer therapeutic strategies. We also discuss limitations and challenges that need to be addressed and provide insights and perspectives to turn challenges into opportunities in this field. Collectively, the discovery and application of multiple tumor biomarkers emphasized in this review may provide guidance on improved precision medicine, broaden horizons in future research directions, and expedite the clinical classification of cancer patients according to their molecular biomarkers rather than organs of origin.

Clinical efficacy of plasmid encoding p62/SQSTM1 (Elenagen) in combination with gemcitabine in patients with platinum-resistant ovarian cancer: a randomized controlled trial

Background

The purpose of this trial is to evaluate the safety and efficacy of ELENAGEN, a novel anticancer therapeutic DNA plasmid encoding p62/SQSTM1 protein, as an adjuvant to chemotherapy with gemcitabine (GEM) in patients with advanced platinum-resistant ovarian cancer.

Methods

This open-label prospective randomized study with two arms. GEM (1000 mg/m2) on days 1 and 8 every 3 weeks was administered in both arms: in the Chemo arm (n = 20), GEM was the only treatment, and in the ELENAGEN arm (n = 20), GEM was supplemented with ELENAGEN (2.5 mg i.m. weekly). The primary endpoint was progression-free survival (PFS), and the secondary endpoint was safety. Antitumor activity was assessed by RECIST 1.1, and criteria safety was assessed according to NCI CTCAE version 5.0.

Results

According to the cutoff data, the median follow-up was 13.8 months. There were no serious adverse events related to ELENAGEN treatment. The median PFS was 2.8 and 7.2 months in the Chemo and ELENAGEN arms, respectively (p Log-Rank = 0.03). Notably, at the time of cutoff, 9 patients (45%) in the ELENAGEN arm did not progress, with the longest PFS recorded thus far being 24 months. Subgroup analysis of patients in both arms demonstrated high efficacy of ELENAGEN in patients with worse prognostic factors: high pretreatment levels of CA125 and progression after platinum-free interval <3 months.

Conclusions

The addition of ELENAGEN to gemcitabine is effective in patients with platinum-resistant ovarian cancer, including those with a worse prognosis.

Clinical trial registration

https://www.clinicaltrials.gov/study/NCT05979298, identifier NCT05979298, 2023-08-07.

Expression and Clinical Significance of IRE1-XBP1s, p62, and Caspase-3 in Colorectal Cancer Patients

Background

Three main cell signaling pathways including the endoplasmic reticulum stress (ERS) response, autophagy, and apoptosis play critical roles in both cell survival and death. They were found to crosstalk with one another during tumorigenesis and cancer progression. This study aimed to investigate the expression of the spliced form of X-box binding protein 1 (XBP1s), p62, and caspase-3, as the essential biomarkers of ERS, autophagy, and apoptosis in patients with colorectal cancer (CRC), as well as the correlation between their expression and clinicopathological data.

Methods

This retrospective study was conducted on formalin-fixed paraffin-embedded (FFPE) blocks, which were collected from patients and their tumor margins, from the tumor bank of Imam Khomeini Hospital (Tehran, Iran) from 2017 to 2019. Tissue microarray (TMA) was used to measure the XBP1s, p62, and caspase-3 biomarkers. Data were analyzed using SPSS software version 20, and P≤0.05 was considered statistically significant.

Results

Evaluating the total of 91 patients, a significant relationship was found between XBP1s expression and TNM stage (P=0.003), primary tumor (pT) (P=0.054), and the degree of differentiation (P=0.006); and between caspase-3 with pT (P=0.004), and lymphovascular invasion (P=0.02). However, no significant correlation was found between p62 and clinicopathological data. Furthermore, a positive relationship between XBP1s and p62 was confirmed (correlation coefficient: 22.2% and P=0.05).

Conclusion

Our findings indicated that XBP1s could be considered as a target for therapy in personalized medicine.

Nrf2 signaling pathway: current status and potential therapeutic targetable role in human cancers

Cancer is a borderless global health challenge that continues to threaten human health. Studies have found that oxidative stress (OS) is often associated with the etiology of many diseases, especially the aging process and cancer. Involved in the OS reaction as a key transcription factor, Nrf2 is a pivotal regulator of cellular redox state and detoxification. Nrf2 can prevent oxidative damage by regulating gene expression with antioxidant response elements (ARE) to promote the antioxidant response process. OS is generated with an imbalance in the redox state and promotes the accumulation of mutations and genome instability, thus associated with the establishment and development of different cancers. Nrf2 activation regulates a plethora of processes inducing cellular proliferation, differentiation and death, and is strongly associated with OS-mediated cancer. What's more, Nrf2 activation is also involved in anti-inflammatory effects and metabolic disorders, neurodegenerative diseases, and multidrug resistance. Nrf2 is highly expressed in multiple human body parts of digestive system, respiratory system, reproductive system and nervous system. In oncology research, Nrf2 has emerged as a promising therapeutic target. Therefore, certain natural compounds and drugs can exert anti-cancer effects through the Nrf2 signaling pathway, and blocking the Nrf2 signaling pathway can reduce some types of tumor recurrence rates and increase sensitivity to chemotherapy. However, Nrf2's dual role and controversial impact in cancer are inevitable consideration factors when treating Nrf2 as a therapeutic target. In this review, we summarized the current state of biological characteristics of Nrf2 and its dual role and development mechanism in different tumor cells, discussed Keap1/Nrf2/ARE signaling pathway and its downstream genes, elaborated the expression of related signaling pathways such as AMPK/mTOR and NF-κB. Besides, the main mechanism of Nrf2 as a cancer therapeutic target and the therapeutic strategies using Nrf2 inhibitors or activators, as well as the possible positive and negative effects of Nrf2 activation were also reviewed. It can be concluded that Nrf2 is related to OS and serves as an important factor in cancer formation and development, thus provides a basis for targeted therapy in human cancers.

Role of autophagy and its regulation by noncoding RNAs in ovarian cancer

Autophagy is a self-digestion process by which misfolded proteins and damaged organelles in eukaryotic cells are degraded to maintain cellular homeostasis. This process is involved in the tumorigenesis, metastasis, and chemoresistance of various tumors such as ovarian cancer (OC). Noncoding RNAs (ncRNAs), mainly including microRNAs, long noncoding RNAs, and circular RNAs, have been extensively investigated in cancer research for their roles in the regulation of autophagy. Recent studies have shown that in OC cells, ncRNAs can modulate the formation of autophagosomes, which affect tumor progression and chemoresistance. An understanding of the role of autophagy in OC progression, treatment, and prognosis is important, and the identification of the regulatory roles of ncRNAs in autophagy leads to intervention strategies for OC therapy. This review summarizes the role of autophagy in OC and discusses the role of ncRNA-mediated autophagy in OC, as an understanding of these roles may contribute to the development of potential therapeutic strategies for this disease.

Autophagy: A challengeable paradox in cancer treatment

OBJECTIVE

Autophagy is an intracellular degradation pathway conserved in all eukaryotes from yeast to humans. This process plays a quality-control role by destroying harmful cellular components under normal conditions, maintaining cell survival, and establishing cellular adaptation under stressful conditions. Hence, there are various studies indicating dysfunctional autophagy as a factor involved in the development and progression of various human diseases, including cancer. In addition, the importance of autophagy in the development of cancer has been highlighted by paradoxical roles, as a cytoprotective and cytotoxic mechanism. Despite extensive research in the field of cancer, there are many questions and challenges about the roles and effects suggested for autophagy in cancer treatment. The aim of this study was to provide an overview of the paradoxical roles of autophagy in different tumors and related cancer treatment options.

METHODS

In this study, to find articles, a search was made in PubMed and Google scholar databases with the keywords Autophagy, Autophagy in Cancer Management, and Drug Design.

RESULTS

According to the investigation, some studies suggest that several advanced cancers are dependent on autophagy for cell survival, so when cancer cells are exposed to therapy, autophagy is induced and suppresses the anti-cancer effects of therapeutic agents and also results in cell resistance. However, enhanced autophagy from using anti-cancer drugs causes autophagy-mediated cell death in several cancers. Because autophagy also plays roles in both tumor suppression and promotion further research is needed to determine the precise mechanism of this process in cancer treatment.

CONCLUSION

We concluded in this article, autophagy manipulation may either promote or hinder the growth and development of cancer according to the origin of the cancer cells, the type of cancer, and the behavior of the cancer cells exposed to treatment. Thus, before starting treatment it is necessary to determine the basal levels of autophagy in various cancers.

The multifaced role and therapeutic regulation of autophagy in ovarian cancer

Ovarian cancer (OC) is one of the tumors that occurs most frequently in women. Autophagy is involved in cell homeostasis, biomolecule recycling, and survival, making it a potential target for anti-tumor drugs. It is worth noting that growing evidence reveals a close link between autophagy and OC. In the context of OC, autophagy demonstrates activity as both a tumor suppressor and a tumor promoter, depending on the context. Autophagy's exact function in OC is greatly reliant on the tumor microenvironment (TME) and other conditions, such as hypoxia, nutritional deficiency, chemotherapy, and so on. However, what can be concluded from different studies is that autophagy-related signaling pathways, especially PI3K/AKT/mTOR axis, increase in advanced stages and malignant phenotype of the disease reduces autophagy and ultimately leads to tumor progression. This study sought to present a thorough understanding of the role of autophagy-related signaling pathways in OC and existing therapies targeting these signaling pathways.

Prognostic relevance of autophagy-related markers p62, LC3, and Beclin1 in ovarian cancer

AIM

To analyze the expression of autophagy markers p62, LC3, and Beclin1 in ovarian cancer tissue and evaluate the prognostic potential of these markers.

METHODS

The study enrolled 328 patients: 122 with epithelial ovarian carcinoma, 42 with atypical proliferative tumor, and 164 with benign epithelial ovarian tumor. The expression of p62, LC3, and Beclin1 was analyzed in central and invasive tumor segments with immunohistochemistry combined with tissue microarray. The expression levels of the analyzed markers were correlated with relevant histopathology parameters.

RESULTS

The expression of all analyzed markers was most remarkable in epithelial ovarian carcinoma. There was a strong positive correlation between the expressions of p62 and LC3, while these two markers negatively correlated with Beclin1. High-grade serous carcinoma had higher p62 and LC3 levels, and lower Beclin1 levels than other tumor types. This expression profile was also observed in more advanced tumor stages.

CONCLUSION

Prominent p62 and LC3 expression in combination with weak Beclin1 expression in high-grade serous carcinoma indicates potential for the application of autophagy inhibitors in patients with this tumor subtype.

Immunohistochemical Expression of p62 in Feline Mammary Carcinoma and Non-Neoplastic Mammary Tissue

The p62 protein, also called sequestosome 1 (SQSTM1), is a ubiquitin-binding scaffold protein. In human oncology, although the interest in the function of this protein is recent, the knowledge is now numerous, but its role in tumorigenesis is not yet clear. This preliminary study aims to evaluate the immunohistochemical expression of p62 in 38 cases of feline mammary carcinoma with different grades of differentiation and in 12 non-neoplastic mammary gland tissues, to assess the expression level and a possible correlation with malignancy. The expression of p62 was statistically higher in carcinoma compared to non-neoplastic mammary glands: 28 feline mammary carcinomas (73.7%) had a high p62 expression score, three (7.9%) had a moderate expression, while seven cases (18.4%) had a low expression. The grade of the differentiation of the carcinoma was not correlated with the p62 expression. This study represents the first approach in feline oncology that correlates p62 expression in feline mammary carcinoma. Our results, although preliminary, are similar to the results of human breast cancer, therefore, also in the cat, p62 could be considered a possible oncotarget.

Abnormal accumulation of OFD1 in endometrial cancer with poor prognosis inhibits ciliogenesis

The aim of the present study was to examine primary cilia in endometrial tissue during the menstrual cycle and to clarify their morphological changes with different grades of endometrial cancer. Images of fluorescence immunostaining taken by confocal microscopy were used to count the number of primary cilia in normal endometrium and endometrioid carcinoma Grade 1 and Grade 3 specimens. To examine the association between autophagy and ciliogenesis in endometrioid carcinoma, the expression of p62/Sequestosome-1, a selective substrate for autophagy, and oral-facial-digital syndrome 1 protein (OFD1), a protein associated with ciliogenesis, were examined using images of fluorescence immunostaining taken by confocal microscopy. The level of p62 expression was confirmed by western blotting. In proliferative and secretory endometrial stromal cells, the percentage of cells that were ciliated was 7.2 and 32.7% (95% confidence interval=21.61-39.79; P<0.01), and the length of the primary cilia was 1.24 µm and 2.34 µm (0.92-1.26; P<0.01), respectively. In stromal cells of endometrioid carcinoma Grade 1 and Grade 3, the percentage of ciliated cells was 13.5 and 2.9% (7.89-15.05; P<0.001), and the length of the primary cilia was 2.02 and 1.14 µm (0.76-0.99; P<0.001), respectively. In both normal menstrual cycle tissue and endometrial carcinomas, the percentage of primary cilia was lower and their length was shorter in tissues with higher proliferative potential. The expression of OFD1 was significantly higher in Grade 3 compared with Grade 1 as indicated by quantifying the intensity of the fluorescence images (133–12248; P=0.046). To the best of our knowledge, this is the first study concerning the distribution of primary cilia in normal endometrium and endometrial cancer tissues. Overall, fewer ciliated cells in the highly malignant endometrial cancer tissues may be associated not only to the proliferation of cancer cells, but also to the excessive accumulation of OFD1 due to dysfunctional autophagy.

Pre-activation of autophagy impacts response to olaparib in prostate cancer cells

Poly (ADP-ribose) polymerase 1 (PARP1) plays an essential role in DNA repair and is targeted by anticancer therapies using PARP inhibitors (PARPi) such as olaparib. PARPi treatment in prostate cancer (PC) is currently used as a monotherapy or in combination with standard therapies (hormonotherapy) in clinical trials for patients with DNA damage response mutation. Unfortunately, 20% of these patients did not respond to this new treatment. This resistance mechanism in PC is still not well understood. Here, we report that autophagy affects differently the response of PC cell lines to olaparib depending on its activation status. Pre-activation of autophagy before olaparib resulted in an increase of DNA repair activity by homologous recombination (HR) to repair double-strand breaks induced by olaparib and enhanced cell proliferation. When autophagy was activated after olaparib treatment, or completely inhibited, PC cells demonstrated an increased sensitivity to this PARPi. This autophagy-mediated resistance is, in part, regulated by the nuclear localization of sequestrosome 1 (SQSTM1/p62). Decrease of SQSTM1/p62 nuclear localization due to autophagy pre-activation leads to an increase of filamin A (FLNA) protein expression and BRCA1/Rad51 recruitment involved in the HR pathway. Our results reveal that autophagy basal levels may in part determine amenability to PARPi treatment.

Pre-activation of autophagy mediates resistance to olaparib by decreasing nuclear SQSTM1/p62, which increases homologous recombination-mediated repair through filamin A expression and BRCA1/Rad51 recruitment.

Dihydrotanshinone I inhibits ovarian tumor growth by activating oxidative stress through Keap1-mediated Nrf2 ubiquitination degradation

Dihydrotanshinone I (DHT), a bioactive compound in Salvia miltiorrhiza, was reported to exhibit cytotoxicity against various malignancies. However, the underlying mechanism on ovarian cancer remains unclear. Here, DHT inhibited cell viability of ovarian cancer HO8910PM, SKOV3, A2780 and ES2 cells. It showed moderate inhibitory effect on ovarian epithelial IOSE80 cells and lower toxicity than chemotherapy drugs. DHT induced apoptosis and G2 cell cycle arrest accompanied by reduced expression of Bcl-2, Caspase-3, and increased Bax. Meanwhile, DHT increased ROS accumulation, decreased mitochondrial membrane potential and activated oxidative stress in HO8910PM and ES2 cells. Mechanistically, DHT inhibited Nrf2 and p62 expression, Nrf2 target genes and enzymes, and Nrf2 nuclear translocation, while increased the expression of Nrf2 inhibitor Keap1. NAC, a ROS scavenger, rescued DHT-induced proliferation inhibition, ROS generation and Nrf2 inhibition. DHT alleviated tBHQ-induced Nrf2 expression and increased its mRNA level. However, the proteasome inhibitor MG132 blocked DHT-induced Nrf2 inhibition, suggesting a post-translational regulation manner. DHT enhanced Nrf2 binding with Keap1, leading to potentiated Nrf2 ubiquitination degradation. Furthermore, Nrf2 and p62 overexpression blocked DHT-induced Nrf2 and p62 inhibition. Consistent with the in vitro results, DHT significantly delayed tumor growth in HO8910PM and ES2 xenograft nude mice, decreased tumor marker HE4 and CA125 levels, reversed the abnormally expressed proteins including Ki67, Nrf2, p62, Keap1, Bcl-2, CyclinB1, Cdc-2, and antioxidant enzymes SOD, CAT in vivo. Serum from DHT-treated mice also inhibited cell growth in vitro. Taken together, DHT exhibits anti-ovarian tumor effect by activating oxidative stress through ubiquitination-mediated Nrf2 degradation. Our findings implicate a potential application of DHT for ovarian cancer therapy.

OSov: An Interactive Web Server to Evaluate Prognostic Biomarkers for Ovarian Cancer

Simple Summary

The OSov web server incorporates gene expression profiles with clinical risk factors to estimate the ovarian cancers patients’ survival, and provides a tool for multiple analysis, such as forest-plot, uni/multi-variate survival analysis, Kaplan-Meier plot and nomogram construction.

Abstract

Ovarian cancer is one of the most aggressive and highly lethal gynecological cancers. The purpose of our study is to build a free prognostic web server to help researchers discover potential prognostic biomarkers by integrating gene expression profiling data and clinical follow-up information of ovarian cancer. We construct a prognostic web server OSov (Online consensus Survival analysis for Ovarian cancer) based on RNA expression profiles. OSov is a user-friendly web server which could present a Kaplan–Meier plot, forest plot, nomogram and survival summary table of queried genes in each individual cohort to evaluate the prognostic potency of each queried gene. To assess the performance of OSov web server, 163 previously published prognostic biomarkers of ovarian cancer were tested and 72% of them had their prognostic values confirmed in OSov. It is a free and valuable prognostic web server to screen and assess survival-associated biomarkers for ovarian cancer.

Combined Evaluation of MAP1LC3B and SQSTM1 for Biological and Clinical Significance in Ductal Carcinoma of Breast Cancer

Breast cancer is the leading cause of cancer death in women worldwide. The microtubule-associated protein light chain 3B (MAP1LC3B) and adaptor sequestosome 1 (SQSTM1) are two major markers for autophagy. Increased protein levels of MAP1LC3B and SQSTM1 are considered to be causes of autophagy inhibition or activation in various types of cancers. However, the roles of MAP1LC3B and SQSTM1 in breast cancer are still not clear. Using a tissue microarray from 274 breast invasive ductal carcinoma (IDC) patients, we found that tumor tissues showed higher protein levels of MAP1LC3B and cytoplasmic SQSTM1 in comparison to those in adjacent normal tissues. Moreover, high levels of MAP1LC3B were associated with better survival, including disease-specific survival and disease-free survival (DFS) in IDC patients. Furthermore, high co-expression of MAP1LC3B and SQSTM1 was significantly associated with better DFS in IDC patients. Astonishingly, the autophagy inhibitor accumulated the protein levels of MAP1LC3B/SQSTM1 and enhanced the cytotoxic effects of cisplatin and paclitaxel in MCF7 and BT474 breast cancer cell lines, implying that autophagy inhibition might result in poor prognosis and chemosensitivity in IDC. Taken together, high co-expression of MAP1LC3B and SQSTM1 might serve as a potential diagnostic and prognostic biomarker for IDC patients.

Sequestosome 1/p62: A multitasker in the regulation of malignant tumor aggression (Review)

Sequestosome 1 (SQSTM1)/p62 is an adapter protein mainly involved in the transportation, degradation and destruction of various proteins that cooperates with components of autophagy and the ubiquitin-proteasome degradation pathway. Numerous studies have shown that SQSTM1/p62 functions at multiple levels, including involvement in genetic stability or modification, post-transcriptional regulation and protein function. As a result, SQSTM1/p62 is a versatile protein that is a critical core regulator of tumor cell genetic stability, autophagy, apoptosis and other forms of cell death, malignant growth, proliferation, migration, invasion, metastasis and chemoradiotherapeutic response, and an indicator of patient prognosis. SQSTM1/p62 regulates these processes via its distinct molecular structure, through which it participates in a variety of activating or inactivating tumor-related and tumor microenvironment-related signaling pathways, particularly positive feedback loops and epithelial-mesenchymal transition-related pathways. Therefore, functioning as a proto-oncogene or tumor suppressor gene in various types of cancer and tumor-associated microenvironments, SQSTM1/p62 is capable of promoting or retarding malignant tumor aggression, giving rise to immeasurable effects on tumor occurrence and development, and on patient treatment and prognosis.

p62/Sequestosome 1 regulates transforming growth factor beta signaling and epithelial to mesenchymal transition in A549 cells

Transforming growth factor beta (TGFβ) receptor trafficking regulates many TGFβ-dependent cellular outcomes including epithelial to mesenchymal transition (EMT). EMT in A549 non-small cell lung cancer (NSCLC) cells has recently been linked to the regulation of cellular autophagy. Here, we investigated the role of the autophagy cargo receptor, p62/sequestosome 1 (SQSTM1), in regulating TGFβ receptor trafficking, TGFβ1-dependent Smad2 phosphorylation and EMT in A549 NSCLC cells. Using immunofluorescence microscopy, p62/SQSTM1 was observed to co-localize with TGFβ receptors in the late endosome. Small interfering RNA (SiRNA)-mediated silencing of p62/SQSTM1 resulted in an attenuated time-course of Smad2 phosphorylation but did not alter Smad2 nuclear translocation. However, p62/SQSTM1 silencing promoted TGFβ1-dependent EMT marker expression, actin stress fiber formation and A549 cell migration. We further observed that Smad4-independent TGFβ1 signaling decreased p62/SQSTM1 protein levels via a proteasome-dependent mechanism. Although p62/SQSTM1 silencing did not impede TGFβ-dependent autophagy, our results suggest that p62/SQSTM1 may aid in maintaining A549 cells in an epithelial state and TGFβ1 decreases p62/SQSTM1 prior to inducing EMT and autophagy.

Knockdown of p62/sequestosome enhances ginsenoside Rh2-induced apoptosis in cervical cancer HeLa cells with no effect on autophagy

p62/sequestosome is a multifunctional adaptor protein that participates in a wide variety of cellular processes. 20(S)-Ginsenoside Rh2 (G-Rh2) has various biological effects, including anticancer activity. We found that G-Rh2 can induce apoptosis and autophagy in HeLa cells. G-Rh2 significantly enhanced the transcriptional level of p62. A siRNA was constructed to knock down p62 and assess its effect on apoptosis induced by G-Rh2. p62 protein levels were successfully downregulated in cells transfected with the p62-specific siRNA. Silencing of p62 further decreased cell viability while also enhancing cell apoptosis, reactive oxygen species generation, the ratio of Bax to Bcl-2, and the cleavage of PARP. p62 knockdown decreased expression levels of Nrf2. Moreover, silencing of p62 had no significant effect on autophagy induced by G-Rh2. These results suggest that combining G-Rh2 treatment with inhibition of p62 may be a potential treatment strategy for cervical cancer.

p62 manipulation affects chlorin e6-mediated photodynamic therapy efficacy in colorectal cancer cell lines

p62 is a multifunctional protein that mediates cell signaling pathways, autophagy and tumorigenesis, and participates in important regulation processes at the intersection between autophagy and cancer. Photodynamic therapy (PDT) is a treatment that involves photosensitizing agents and light to kill cancer cells. However, whether the efficacy of PDT depends on the expression level of p62 in colorectal cancer cell lines is not known. The present study aimed to examine the role of p62 expression levels in chlorin e6-based PDT in colorectal cancer cells. To study the effect of p62 on cancer cell death, we used PDT to treat a stable cell line overexpressing p62. Cells overexpressing p62 showed a higher cell death rate than cells not expressing this protein. Overexpression of p62 may contribute to colorectal cancer cell death. These results provide preliminary evidence for use of p62 as a therapy target to treat colorectal cancer.

Ailanthone increases oxidative stress in CDDP-resistant ovarian and bladder cancer cells by inhibiting of Nrf2 and YAP expression through a post-translational mechanism

Chemoresistance represents one of the main obstacles in treating several types of cancer, including bladder and ovarian cancers, and it is characterized by an increase of cellular antioxidant potential. Nrf2 and YAP proteins play an important role in increasing chemoresistance and in inducing antioxidant enzymes. It has been reported that Ailanthone (Aila), a compound extracted from the Ailanthus Altissima, has an anticancer activity toward several cancer cell lines, including chemoresistant cell lines. We have examined the effect of Aila on proliferation, migration and expression of Nrf2 and YAP proteins in A2780 (CDDP-sensitive) and A2780/CP70 (CDDP-resistant) ovarian cancer cells. Furthermore, to clarify the mechanism of Aila action we extended our studies to sensitive and CDDP-resistant 253J-BV bladder cancer cells, which have been used in a previous study on the effect of Aila. Results demonstrated that Aila exerted an inhibitory effect on growth and colony formation of sensitive and CDDP-resistant ovarian cancer cells and reduced oriented cell migration with higher effectiveness in CDDP resistant cells. Moreover, Aila strongly reduced Nrf2 and YAP protein expression and reduced the expression of the Nrf2 target GSTA4, and the YAP/TEAD target survivin. In CDDP-resistant ovarian and bladder cancer cells the intracellular oxidative stress level was lower with respect to the sensitive cells. Moreover, Aila treatment further reduced the superoxide anion content of CDDP-resistant cells in correlation with the reduction of Nrf2 and YAP proteins. However, Aila treatment increased Nrf2 and YAP mRNA expression in all cancer cell lines. The inhibition of proteolysis by MG132, a proteasoma inhibitor, restored Nrf2 and YAP protein expressions, suggesting that the Aila effect was at post-translational level. In accordance with this observation, we found an increase of the Nrf2 inhibitor Keap1, a reduction of p62/SQSTM1, a Nrf2 target which leads Keap1 protein to the autophagic degradation, and a reduction of P-YAP. Moreover, UCHL1 deubiquitinase expression, which was increased in bladder and ovarian resistant cells, was down-regulated by Aila treatment. In conclusion we demonstrated that Aila can reduce proliferation and migration of cancer cells through a mechanism involving a post translational reduction of Nrf2 and YAP proteins which, in turn, entailed an increase of oxidative stress particularly in the chemoresistant lines.

Fibroblast Growth Factor 1 Ameliorates Diabetes-Induced Liver Injury by Reducing Cellular Stress and Restoring Autophagy

Background

Type 2 diabetes (T2D) is a metabolic dysfunction disease that causes several complications. Liver injury is one of these that severely affects patients with diabetes. Fibroblast growth factor 1 (FGF1) has glucose-lowering activity and plays a role in modulation of several liver injuries. Nevertheless, the effects and potential mechanisms of FGF1 against diabetes-induced liver injury are unknown.

Methods

To further investigate the effect of FGF1 on diabetic liver injury, we divided db/db mice into two groups and intraperitoneally (i.p.) injected either with FGF1 at 0.5 mg/kg body weight or saline every other day for 4 weeks. Then body weights were measured. Serum and liver tissues were collected for biochemical and molecular analyses.

Results

FGF1 significantly reduced blood glucose and ameliorated diabetes-induced liver steatosis, fibrosis, and apoptosis. FGF1 also restored defective hepatic autophagy in db/db mice. Mechanistic investigations showed that diabetes markedly induced oxidative stress and endoplasmic reticulum stress and that FGF1 treatment significantly attenuated these effects.

Conclusions

FGF1-associated glucose level reduction and amelioration of cellular stress are potential protective effects of FGF1 against diabetes-induced liver injury.

PDCD4 inhibits lung tumorigenesis by the suppressing p62-Nrf2 signaling pathway and upregulating Keap1 expression

Programmed cell death 4 (PDCD4) suppresses tumorigenesis, tumor progression, and invasion by inhibiting transcription and translation of oncogenes. However, the role of PDCD4 in lung tumorigenesis is unclear. Sequestosome1/p62 mediates cell proliferation, survival, and death through multiple signaling pathways, including autophagy and cell metabolism. p62/SQSTM1 is transcriptional target of Nrf2 and an important regulator of tumor growth. The aim of this study was to clarify whether and how PDCD4 regulates the p62-Nrf2 pathway, and how this regulation relates to tumorigenesis in human lung cancer cells. We established two stable human lung cancer cell lines, A549 and H460 that each overexpressed PDCD4. We found that PDCD4 overexpression decreased p62 expression levels and inhibited cell proliferation, and also increased the expression levels of cleaved PARP and cleaved caspase 3. Knockdown of p62 markedly increased the apoptotic rate of A549 and H460 cells overexpressing PDCD4. Furthermore levels of the epithelial-mesenchymal transition-related markers Slug, Snail, Twist1 and Vimentin were decreased and expression level of E-cadherin was increased in PDCD4-overexpressing cells. We also found that PDCD4 suppressed transcriptional activation of Nrf2 (an upstream regulator of p62) and increased endogenous levels of Keap1 (a negative regulator of Nrf2). Upregulation of Keap1 induced apoptosis and inhibited cell proliferation by suppressing activity of the p62-Nrf2 pathway in PDCD4-overexpressing cells. As anticipated, results from a mouse xenograft model showed that PDCD4 overexpression in xenografts inhibited cell proliferation and tumorigenesis. Taken together, our results demonstrate that PDCD4 overexpression, which increased Keap1 expression, reduces the levels and activity of the p62-Nrf2 pathway, thereby inhibiting tumorigenesis. Our findings suggest that PDCD4 may be a potential target for lung cancer therapies.

Ovarian cancer therapeutic potential of glutamine depletion based on GS expression

Amino acids (AAs) are biologically important nutrient compounds necessary for the survival of any cell. Of the 20 AAs, cancer cells depend on the uptake of several extracellular AAs for survival. However, which extracellular AA is indispensable for the survival of cancer cells and the molecular mechanism involved have not been fully defined. In this study, we found that the reduction of cell survival caused by glutamine (Gln) depletion is inversely correlated with the expression level of glutamine synthetase (GS) in ovarian cancer (OVC) cells. GS expression was downregulated in 45 of 316 OVC cases (14.2%). The depletion of extracellular Gln by treatment with l-asparaginase, in addition to inhibiting Gln uptake via the knockdown of a Gln transporter, led to the inhibition of cell growth in OVC cells with low expression of GS (GSlow-OVC cells). Furthermore, the re-expression of GS in GSlow-OVC cells induced the inhibition of tumor growth in vitro and in vivo. Thus, these findings provide novel insight into the development of an OVC therapy based on the requirement of Gln.

Enhanced basal autophagy supports ameloblastoma-derived cell survival and reactivation

OBJECTIVES

Ameloblastoma is an aggressive odontogenic jaw neoplasm. Its unlimited growth confers high potential for malignant transformation and recurrence. It is unclear why ameloblastoma is highly recurrent despite surgical resection with a wide margin of normal tissue. While canonical autophagy can be used to degrade and eliminate damaged cellular components, it is also a protective mechanism that provides energy and vital metabolites for cell survival. We used ameloblastoma-derived cells to test the hypothesis that autophagic processes play a role in survival and reactivation of ameloblastoma.

METHODS

Primary epithelial (EP-AMCs) and mesenchymal (MS-AMCs) ameloblastoma-derived cells were established from tissue samples of solid multicystic ameloblastoma. Clonogenic capacity and basal autophagic capacity were assessed in ameloblastoma-derived cells relative to human odontoma-derived cells (HODCs) and maxilla-mesenchymal stem cells (MX-MSCs). Ability of ameloblastoma-derived cells to survive and form new ameloblastoma was assessed in mouse tumor xenografts.

RESULTS

EP-AMCs were highly clonogenic (p < 0.0001) and demonstrated enhanced basal levels of autophagic proteins microtubule-associated protein 1-light chain 3 (LC3) (p < 0.01), p62 (Sequestosome 1, SQSTM1) (p < 0.01), and the LC3-adapter, melanoregulin (MREG) (p < 0.05) relative to controls. EP-AMCs xenografts regenerated solid ameloblastoma-like tumor with histological features of columnar ameloblast-like cells, loose stellate reticulum-like cells and regions of cystic degeneration characteristic of follicular variant of solid multicystic ameloblastoma. The xenografts also displayed stromal epithelial invaginations strongly reactive to LC3 and p62 suggestive of epithelial-mesenchymal transition and neoplastic odontogenic epithelium.

CONCLUSIONS

EP-AMCs exhibit altered autophagic processes that can support survival and recurrence of post-surgical ameloblastoma cells.

p62/SQSTM1 - steering the cell through health and disease

SQSTM1 (also known as p62) is a multifunctional stress-inducible scaffold protein involved in diverse cellular processes. Its functions are tightly regulated through an extensive pattern of post-translational modifications, and include the isolation of cargos degraded by autophagy, induction of the antioxidant response by the Keap1-Nrf2 system, as well as the regulation of endosomal trafficking, apoptosis and inflammation. Accordingly, malfunction of SQSTM1 is associated with a wide range of diseases, including bone and muscle disorders, neurodegenerative and metabolic diseases, and multiple forms of cancer. In this Review, we summarize current knowledge regarding regulation, post-translational modifications and functions of SQSTM1, as well as how they are dysregulated in various pathogenic contexts.

Cytoplasmic SQSTM1/ P62 Accumulation Predicates a Poor Prognosis in Patients with Malignant Tumor

Aims: SQSTM1/p62, as an autophagy marker, is a key molecule involved in the autophagy process. Recent studies have demonstrated that p62 has a close relationship with tumorigenesis and progression, but the impact of p62 on patients' survival has not been comprehensively understood. Therefore, we conducted this study to assess the expression level of p62 in tumor cells and the prognostic role of p62 expression in various malignant tumors. Methods: We searched PubMed, PubMed Central (PMC), Embase, Ovid and Web of Science databases and identified 30 eligible studies containing 14,072 patients to include in the meta-analysis. The p62 mRNA and protein expression profiles in various tumor tissues and normal tissues were presented according to the Human Protein Atlas (HPA) and the Gene Expression Profiling Interactive Analysis (GEPIA). We also tested the association between p62 mRNA level and patients' survival based on the Cancer Genome Atlas (TCGA) and the Human Protein Atlas (HPA) databases. Results: The expression levels of p62 mRNA and protein varied in different tissues. The p62 proteins were elevated and mainly located in the cytoplasm in some types of tumor compared with the normal tissues. The pooled results indicated that p62 overexpression in tumor tissues was associated with a worse prognosis. In the subgroup analysis, a significant relationship was observed between cytoplasmic p62 accumulation and both overall survival (HR 1.53, 95% CI: 1.03-2.27, P < 0.05) and disease-specific survival (HR 1.60, 95% CI: 1.15-2.24, P < 0.01). The relationship between p62 and worse survival was more evident in early stage tumors. P62 mRNA expression had no significant effect on the patient's survival except of liver cancer. Conclusions: The findings of this meta-analysis highlight the role of p62 as a useful prognostic biomarker for some types of tumor according to different clinicopathologic features, which may contribute to the selection of effective treatment methods for different malignant tumors.

Autophagy is positively associated with the accumulation of myeloid‑derived suppressor cells in 4‑nitroquinoline‑1‑oxide‑induced oral cancer

It has previously been demonstrated that autophagy and inflammation act synergistically to promote carcinogenesis. However, the precise roles of autophagy in multistep oral carcinogenesis are still unclear, particularly regarding its association with tumor inflammation. The present study established a 4NQO-induced oral cancer mouse model and investigated autophagy status in the multistep process of oral carcinogenesis using immunohistochemistry, western blotting and immunofluorescence staining. Furthermore, the number of Gr-1⁺CD11b⁺ myeloid derived suppressor cells (MDSCs) and CD4⁺ Foxp3⁺ regulatory T cells (Tregs) during oral carcinogenesis and the association with autophagy status was also examined. The results revealed that the expression of autophagy biomarkers, including dihydrosphingosine 1-phosphate phosphatase LCB3 (LC3B), p62/SQSTM1 (p62) and Beclin 1 increased during 4NQO-induced carcinogenesis and in human oral cancer. The number of MDSCs and Tregs also increased during oral carcinogenesis. Furthermore, the expression of LC3B and p62 significantly correlated with the accumulation of MDSCs and the expression of Beclin 1 correlated with the increase of Tregs. These data indicated that autophagy may be activated by the tumor inflammation microenvironment during oral carcinogenesis.

Activation of p62/SQSTM1-Keap1-Nuclear Factor Erythroid 2-Related Factor 2 Pathway in Cancer

Autophagy and the Keap1–Nrf2 system are major cellular defense mechanisms against metabolic and oxidative stress. These two systems are linked via phosphorylation of the ubiquitin binding autophagy receptor protein p62/SQSTM1 in the p62–Keap1–Nrf2 pathway. The p62–Keap1–Nrf2 pathway plays a protective role in normal cells; however, recent studies indicate that this pathway induces tumorigenesis of pre-malignant cells, and promotes the growth and drug resistance of tumor cells via metabolic reprogramming mediated by Nrf2 activation. These findings suggest that impairment of autophagy is involved in the acquisition of malignancy and maintenance of tumors, and furthermore, that p62/SQSTM1 could be a potential target for chemotherapy in cancers that harbor excess p62.

Autophagy as an emerging therapy target for ovarian carcinoma

Autophagy is a conserved cellular self-digestion pathway for maintenance of homeostasis under basal and stressed conditions. Autophagy plays pivotal roles in the pathogenesis of many diseases, such as aging-related diseases, autoimmune diseases, cardiovascular diseases, and cancers. Of special note is that accumulating data suggest an intimate relationship between autophagy and ovarian carcinoma. Autophagy is well identified to act as either as a tumor-suppressor or as a tumor-promoter in ovarian carcinoma. The exact function of autophagy in ovarian carcinoma is highly dependent on the circumstances of cancer including hypoxic, nutrient-deficient, chemotherapy and so on. However, the mechanism underlying autophagy associated with ovarian carcinoma remains elusive, the precise role of autophagy in ovarian carcinoma also remains undetermined. In this review, we tried to sum up and discuss recent research achievements of autophagy in ovarian cancer. Moreover, waves of novel therapies ways for ovarian carcinoma based on the functions of autophagy were collected.

Quinacrine upregulates p21/p27 independent of p53 through autophagy-mediated downregulation of p62-Skp2 axis in ovarian cancer

We have previously shown that the anti-malarial compound Quinacrine (QC) inhibits ovarian cancer (OC) growth by modulating autophagy. In the present study we extended these studies to identify the molecular pathways regulated by QC to promote apoptosis independent of p53 status in OC. QC exhibited strong anti-cancer properties in OC cell lines in contrast to other anti-malarial autophagy inhibiting drugs. QC treatment selectively upregulated cell cycle inhibitor p21, and downregulated F box protein Skp2 and p62/SQSTM1 expression independent of p53 status. Genetic downregulation of key autophagy protein ATG5 abolished QC-mediated effects on both cell cycle protein p21/Skp2 as well as autophagic cargo protein p62. Furthermore, genetic silencing of p62/SQSTM1 resulted in increased sensitivity to QC-mediated apoptosis, downregulated Skp2 mRNA and increased accumulation of p21 expression. Likewise, genetic knockdown of Skp2 resulted in the upregulation of p21 and p27 and increased sensitivity of OC cells to QC treatment. In contrast, transient overexpression of exogenous p62-HA plasmid rescued the QC-mediated Skp2 downregulation indicating the positive regulation of Skp2 by p62. Collectively, these data indicate that QC-mediated effects on cell cycle proteins p21/Skp2is autophagy-dependent and p53-independent in high grade serious OC cells.

The prognostic value of p62 in solid tumor patients: a meta-analysis

p62, as a scaffolding/adaptor protein, is involved in multiple physiological processes include inflammation, autophagy and mitosis. However, the influence of p62 in cancer patients has not been comprehensively investigated. Moreover, the prognostic value of p62 for the survival of patients with solid tumors remains controversial. In this present meta-analysis, twenty suitable articles were identified from PubMed, EMBASE and Web of Science, Nature databases, including 4271 patients. A random-effect or fixed-effect model was adopted to correlate p62 expression with different outcome measured in entire tumors. Combined with results of hazard ratios (HRs) and 95% confidence intervals (CIs), we concluded that higher expression of p62 is associated with poorer overall survival (OS) (HR: 2.22, 95% CI: 1.82–2.71, P < 0.05), disease-free survival (DFS) (HR = 2.48, 95% CI: 1.78–3.46, P < 0.05) and even certain clinicopathological parameters, such as lymph node metastasis (RR = 1.21, 95% CI: 1.06–1.37) and clinical stages (RR = 1.27, 95% CI: 1.12–1.45), in cancer patients. Consequently, our data showed that p62 might be an effective poor prognostic factor for patients with various solid tumors.

Isoliquiritigenin Induces Autophagy and Inhibits Ovarian Cancer Cell Growth

Ovarian cancer is one of the commonest gynecologic malignancies, which has a poor prognosis for patients at the advanced stage. Isoliquiritigenin (ISL), an active flavonoid component of the licorice plant, previously demonstrated antioxidant, anti-inflammatory, and tumor suppressive effects. In this study, we investigated the antitumor effect of ISL on human ovarian cancer in vitro using the human ovarian cancer cell lines, OVCAR5 and ES-2, as model systems. Our results show that ISL significantly inhibited the viability of cancer cells in a concentration- and time-dependent manner. Flow cytometry analysis indicated that ISL induced G2/M phase arrest. Furthermore, the expression of cleaved PARP, cleaved caspase-3, Bax/Bcl-2 ratio, LC3B-II, and Beclin-1 levels were increased in western blot analysis. To clarify the role of autophagy and apoptosis in the effect of ISL, we used the autophagy inhibitor-3-methyladenine (3-MA) to attenuate the punctate fluorescence staining pattern of the p62/sequestosome 1 (SQSTM1, red fluorescence) and LC3 (green fluorescence) proteins after ISL treatment, and 3-MA inhibited the cytotoxicity of ISL. These findings provide new information about the link between ISL-induced autophagy and apoptosis and suggest that ISL is a candidate agent for the treatment of human ovarian cancer.

Clinical Applications of Autophagy Proteins in Cancer: From Potential Targets to Biomarkers

Autophagy, a lysosome-mediated intracellular degradation and recycling pathway, plays multiple context-dependent roles in tumorigenesis and treatment resistance. Encouraging results from various preclinical studies have led to the initiation of numerous clinical trials with the intention of targeting autophagy in various cancers. Accumulating knowledge of the particular mechanisms and players involved in different steps of autophagy regulation led to the ongoing discovery of small molecule inhibitors designed to disrupt this highly orchestrated process. However, the development of validated autophagy-related biomarkers, essential for rational selection of patients entering clinical trials involving autophagy inhibitors, is lagging behind. One possible source of biomarkers for this purpose is the autophagy machinery itself. In this review, we address the recent trends, challenges and advances in the assessment of the biomarker potential of clinically relevant autophagy proteins in human cancers.

p62/SQSTM1 as an oncotarget mediates cisplatin resistance through activating RIP1-NF-κB pathway in human ovarian cancer cells

Platinum‐based therapeutic strategies have been widely used in ovarian cancer treatment. However, drug resistance has greatly limited therapeutic efficacy. Recently, tolerance to cisplatin has been attributed to other factors unrelated to DNA. p62 (also known as SQSTM1) functions as a multifunctional hub participating in tumorigenesis and may be a therapeutic target. Our previous study showed that p62 was overexpressed in drug‐resistant ovarian epithelial carcinoma and its inhibition increased the sensitivity to cisplatin. In this study, we demonstrate that the activity of the NF‐κB signaling pathway and K63‐linked ubiquitination of RIP1 was higher in cisplatin‐resistant ovarian (SKOV3/DDP) cells compared with parental cells. In addition, cisplatin resistance could be reversed by inhibiting the expression of p62 using siRNA. Furthermore, deletion of the ZZ domain of p62 that interacts with RIP1 in SKOV3 cells markedly decreased K63‐linked ubiquitination of RIP1 and inhibited the activation of the NF‐κB signaling pathway. Moreover, loss of the ZZ domain from p62 led to poor proliferative capacity and high levels of apoptosis in SKOV3 cells and made them more sensitive to cisplatin treatment. Collectively, we provide evidence that p62 is implicated in the activation of NF‐κB signaling that is partly dependent on RIP1. p62 promotes cell proliferation and inhibits apoptosis thus mediating drug resistance in ovarian cancer cells.

Hyper-phosphorylation of Sequestosome-1 Distinguishes Resistance to Cisplatin in Patient Derived High Grade Serous Ovarian Cancer Cells

Platinum-resistance is a major limitation to effective chemotherapy regimens in high-grade serous ovarian cancer (HGSOC). To better understand the mechanisms involved we characterized the proteome and phosphoproteome in cisplatin sensitive and resistant HGSOC primary cells using a mass spectrometry-based proteomic strategy. PCA analysis identified a distinctive phosphoproteomic signature between cisplatin sensitive and resistant cell lines. The most phosphorylated protein in cisplatin resistant cells was sequestosome-1 (p62/SQSTM1). Changes in expression of apoptosis and autophagy related proteins Caspase-3 and SQSTM1, respectively, were validated by Western blot analysis. A significant increase in apoptosis in the presence of cisplatin was observed in only the sensitive cell line while SQSTM1 revealed increased expression in the resistant cell line relative to sensitive cell line. Furthermore, site-specific phosphorylation on 20 amino acid residues of SQSTM1 was detected indicating a hyper-phosphorylation phenotype. This elevated hyper-phosphorylation of SQSTM1 in resistant HGSOC cell lines was validated with Western blot analysis. Immunofluoresence staining of s28-pSQSTM1 showed inducible localization to autophagosomes upon cisplatin treatment in the sensitive cell line while being constitutively expressed to autophagosomes in the resistant cell. Furthermore, SQSTM1 expression was localized in cancer cells of clinical high-grade serous tumors. Here, we propose hyper-phosphorylation of SQSTM1 as a marker and a key proteomic change in cisplatin resistance development in ovarian cancers by activating the autophagy pathway and influencing down-regulation of apoptosis.

p62/SQSTM1 levels predicts radiotherapy resistance in hypopharyngeal carcinomas

Hypopharyngeal carcinoma is one of the worst prognostic malignancies among head and neck carcinomas. Therefore, a good biomarker should be identified to predict the best therapeutic option before starting the treatment. In cell models, p62/SQSTM1 levels affected the Nrf2-Keap1 pathway, ROS levels, GSH/GSSG ratios and cell growth, especially under irradiation rather than under CDDP exposure, which was toxic despite p62/SQSTM1 status. In a clinical cohort of hypopharyngeal carcinomas, high levels of p62/SQSTM1 significantly predicted poor prognosis (log-rank test, Chi-square value = 6.750, P = 0.0094) and maximum critical risk (Cox proportional hazard ratio = 4.405, P = 0.0086), especially in the radiotherapy group. Therefore, when p62/SQSTM1 is elevated in the biopsy section, hypopharyngeal carcinoma should be treated with surgical and/or chemotherapeutic options.

Safety and efficacy of p62 DNA vaccine ELENAGEN in a first-in-human trial in patients with advanced solid tumors

Elenagen is a plasmid encoding p62/SQSTM1, the first DNA vaccine possessing two mutually complementing mechanisms of action: it elicits immune response against p62 and mitigates systemic chronic inflammation. Previously, Elenagen demonstrated anti-tumor efficacy and safety in rodent tumor models and spontaneous tumors in dogs. This multicenter I/IIa trial evaluated safety and clinical activity of Elenagen in patients with advanced solid tumors. Fifteen patients were treated with escalating doses of Elenagen (1- 5 mg per doses, 5 times weekly) and additional 12 patients received 1 mg dose. Ten patients with breast and ovary cancers that progressed after Elenagen were then treated with conventional chemotherapy. Adverse events (AE) were of Grade 1; no severe AE were observed. Cumulatively twelve patients (44%) with breast, ovary, lung, renal cancer and melanoma achieved stable disease for at least 8 wks, with 4 of them (15%) had tumor control for more than 24 wks, with a maximum of 32 wks. The patients with breast and ovary cancers achieved additional tumor stabilization for 12-28 wks when treated with chemotherapy following Elenagen treatment. Therefore, Elenagen demonstrated good safety profile and antitumor activity in advanced solid tumors. Especially encouraging is its ability to restore tumor sensitivity to chemotherapy.

The second annual conference of International ovarian cancer consortium and the symposium on tumor microenvironment and therapeutic resistance

The second Annual Meeting of the International Ovarian Cancer Consortium (IOCC) was held in conjunction with the Symposium on Tumor Microenvironment and Therapeutic Resistance at the Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, and USA. A brief welcoming event along with the banquet on Aug 16th was followed by the eight thematic scientific sessions from August 16 to 18, 2015. Forty-three lectures, organized in eight sessions, were discussed in front of an audience of more than hundred attendees. Emphasis was put on oncogene signaling in cancer genesis and progression, new approaches in Precision Medicine and therapy of ovarian cancer, the role of tumor microenvironment in carcinogenesis, and preventive/curative potential of natural products. In this meeting-report, we highlight the findings and the perspectives in cancer biology and therapeutic strategies that emerged during the conference.

High Expression of p62 Protein Is Associated with Poor Prognosis and Aggressive Phenotypes in Endometrial Cancer

High expression of SQSTM1/p62 (p62) protein, which functions as a hub of oncogenic signaling pathways, has been detected in several human cancers. However, the clinicopathological and functional contribution of p62 expression is largely unknown in endometrial cancers (ECs). In this study, we assessed the expression status of p62 in primary ECs (n = 194) by immunohistochemistry and analyzed its clinical significance. Although p62 was expressed in the cytoplasm and/or nucleus in primary ECs, we observed that an expression subtype, high expression of cytoplasmic p62 but low expression of nuclear p62 (cytoplasm(High)/nucleus(Low)), significantly correlated with nonendometrioid types (P = 0.002), high grade (P < 0.001), deep myometrial invasion (P = 0.025), vascular invasion (P = 0.012), and poor prognosis (P < 0.001), and may be an independent prognostic marker of ECs (P = 0.011). Furthermore, RNA interference-mediated inhibition of p62 expression in the HEC-1A EC cell line led to the reduction of invasiveness and resistance to oxidative stress in vitro, as well as the suppression of in vivo tumor growth in an orthotopic mouse model of ECs. High expression of cytoplasmic p62 is a novel prognostic biomarker of ECs, and excess p62 expression may functionally contribute to the acquirement of malignant phenotypes in EC cells.