All for one and FOSL1 for all: FOSL1 at the crossroads of lung and pancreatic cancer driven by mutant KRAS

AP1/Fra1 confers resistance to MAPK cascade inhibition in pancreatic cancer

Targeting KRAS downstream signaling remains an important therapeutic approach in pancreatic cancer. We used primary pancreatic ductal epithelial cells and mouse models allowing the conditional expression of oncogenic Kras^G12D, to investigate KRAS signaling integrators. We observed that the AP1 family member FRA1 is tightly linked to the KRAS signal and expressed in pre-malignant lesions and the basal-like subtype of pancreatic cancer. However, genetic-loss-of-function experiments revealed that FRA1 is dispensable for Kras^G12D-induced pancreatic cancer development in mice. Using FRA1 gain- and loss-of-function models in an unbiased drug screen, we observed that FRA1 is a modulator of the responsiveness of pancreatic cancer to inhibitors of the RAF-MEK-ERK cascade. Mechanistically, context-dependent FRA1-associated adaptive rewiring of oncogenic ERK signaling was observed and correlated with sensitivity to inhibitors of canonical KRAS signaling. Furthermore, pharmacological-induced degradation of FRA1 synergizes with MEK inhibitors. Our studies establish FRA1 as a part of the molecular machinery controlling sensitivity to MAPK cascade inhibition allowing the development of mechanism-based therapies.

ALKBH5 promotes the progression of infantile hemangioma through regulating the NEAT1/miR-378b/FOSL1 axis

Our work aims to investigate long non-coding RNA (lncRNA) N6-methyladenosine (m⁶A) modification and its role in infantile hemangioma (IH). The mRNA and protein expression levels were assessed using quantitative real-time polymerase chain reaction, western blot and immunohistochemistry. Me-RIP assay was performed to evaluate lncRNA NEAT1 m⁶A levels. Cell proliferation, migration and invasion were evaluated using cell counting kit-8 assay, transwell migration and invasion assay, respectively. Photo-activatable ribonucleoside-enhanced crosslinking and immunoprecipitation assay was conducted to verify the binding relationship between lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) and ALKBH5 (an RNA demethylase). The binding relationship between lncRNA NEAT1, microRNA (miR)-378b and FOS-like antigen 1 (FOSL1) was verified using dual-luciferase reporter gene assay and/or RNA immunoprecipitation assay. ALKBH5, lncRNA NEAT1 and FOLS1 expression was elevated in IH tissues, while miR-378b was downregulated. ALKBH5 knockdown suppressed cell proliferation, migration and invasion of IH cells, while promoting cell apoptosis. ALKBH5 promoted lncRNA NEAT1 expression by reducing the m⁶A modification of lncRNA NEAT1. In addition, miR-378b was the target of lncRNA NEAT1, and its overexpression reversed the promotion effect of lncRNA NEAT1 overexpression on IH cell tumor-like behaviors. Moreover, FOLS1 was the target of miR-378b, and its overexpression reversed the inhibitory effect of miR-378b overexpression on IH cell tumor-like behaviors in vitro. ALKBH5 might have great potential as therapeutic target for IH, since ALKBH5 silencing suppressed IH progression by regulation of the NEAT1/miR-378b/FOSL1 axis.

RETRACTED: MiR-15a-5p targets FOSL1 to inhibit proliferation and promote apoptosis of keratinocytes via MAPK/ERK pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors. According to the authors, concerns with the experimental conduct presented in the paper have been identified, in addition to the grounds that that ethical approval was not sought or confirmed for the research undertaken. After a review, the Editor has confirmed approval that this paper should be retracted as it presents a violation of the Journal’s publishing policies and publishing ethics standards.

Signaling levels mold the RAS mutation tropism of urethane

RAS genes are commonly mutated in human cancer. Despite many possible mutations, individual cancer types often have a 'tropism' towards a specific subset of RAS mutations. As driver mutations, these patterns ostensibly originate from normal cells. High oncogenic RAS activity causes oncogenic stress and different oncogenic mutations can impart different levels of activity, suggesting a relationship between oncoprotein activity and RAS mutation tropism. Here, we show that changing rare codons to common in the murine Kras gene to increase protein expression shifts tumors induced by the carcinogen urethane from arising from canonical Q₆₁ to biochemically less active G₁₂ Kras driver mutations, despite the carcinogen still being biased towards generating Q₆₁ mutations. Conversely, inactivating the tumor suppressor p53 to blunt oncogenic stress partially reversed this effect, restoring Q₆₁ mutations. One interpretation of these findings is that the RAS mutation tropism of urethane arises from selection in normal cells for specific mutations that impart a narrow window of signaling that promotes proliferation without causing oncogenic stress.

Gene signature for prognosis in comparison of pancreatic cancer patients with diabetes and non-diabetes

BACKGROUND

Pancreatic cancer (PC) has much weaker prognosis, which can be divided into diabetes and non-diabetes. PC patients with diabetes mellitus will have more opportunities for physical examination due to diabetes, while pancreatic cancer patients without diabetes tend to have higher risk. Identification of prognostic markers for diabetic and non-diabetic pancreatic cancer can improve the prognosis of patients with both types of pancreatic cancer.

METHODS

Both types of PC patients perform differently at the clinical and molecular levels. The Cancer Genome Atlas (TCGA) is employed in this study. The gene expression of the PC with diabetes and non-diabetes is used for predicting their prognosis by LASSO (Least Absolute Shrinkage and Selection Operator) Cox regression. Furthermore, the results are validated by exchanging gene biomarker with each other and verified by the independent Gene Expression Omnibus (GEO) and the International Cancer Genome Consortium (ICGC). The prognostic index (PI) is generated by a combination of genetic biomarkers that are used to rank the patient's risk ratio. Survival analysis is applied to test significant difference between high-risk group and low-risk group.

RESULTS

An integrated gene prognostic biomarker consisted by 14 low-risk genes and six high-risk genes in PC with non-diabetes. Meanwhile, and another integrated gene prognostic biomarker consisted by five low-risk genes and three high-risk genes in PC with diabetes. Therefore, the prognostic value of gene biomarker in PC with non-diabetes and diabetes are all greater than clinical traits (HR = 1.102, P-value < 0.0001; HR = 1.212, P-value < 0.0001). Gene signature in PC with non-diabetes was validated in two independent datasets.

CONCLUSIONS

The conclusion of this study indicated that the prognostic value of genetic biomarkers in PCs with non-diabetes and diabetes. The gene signature was validated in two independent databases. Therefore, this study is expected to provide a novel gene biomarker for predicting prognosis of PC with non-diabetes and diabetes and improving clinical decision.

Low expression of FOSL1 is associated with favorable prognosis and sensitivity to radiation/pharmaceutical therapy in lower grade glioma

Objectives: FOSL1 is overexpressed in multiple cancers including malignant glioma and contributes to different cellular processes. However, little attention has been paid to the lower grade glioma (LGG).Methods: Cox coefficients were examined to compare FOSL1 expression among different tumors types using OncoLnc. The UCSC Xena browser was used to generate Kaplan-Meier survival curves and explore the association between FOSL1 expression and overall survival (OS) in TCGA-LGG and subgroups.Results: FOSL1 expression in LGG was ranked first among 21 different cancers. LGG with lower FOSL1 expression had longer OS (P < 0.001). The astrocytoma group had the highest FOSL1 expression and shortest OS, followed by oligoastrocytoma and oligodendroglioma (P < 0.05). The 1p19q co-deletion or IDH mutation subgroups had lower FOSL1 expression and longer OS (P < 0.001). Compared with the corresponding groups, LGG with lower FOSL1 expression had longer OS than the following groups: astrocytoma, oligodendroglioma, with/without 1p19q co-deletion, with IDH mutation, with radiation, and with pharmaceutical therapy (P < 0.05).Discussion: FOSL1 is a prognostic marker in LGG and subgroups.

Evolutionarily novel genes are expressed in transgenic fish tumors and their orthologs are involved in development of progressive traits in humans

Abstract

Earlier we suggested a new hypothesis of the possible evolutionary role of hereditary tumors (Kozlov, Evolution by tumor Neofunctionalization, 2014), and described a new class of genes – tumor specifically expressed, evolutionarily novel (TSEEN) genes - that are predicted by this hypothesis (Kozlov, Infect Agents Cancer 11:34, 2016). In this paper we studied evolutionarily novel genes expressed in fish tumors after regression, as a model of evolving organs. As evolutionarily novel genes may not yet have organismal functions, we studied the acquisition of new gene functions by comparing fish evolutionarily novel genes with their human orthologs. We found that many genes involved in development of progressive traits in humans (lung, mammary gland, placenta, ventricular septum, etc.) originated in fish and are expressed in fish tumors and tumors after regression. These findings support a possible evolutionary role of hereditary tumors, and in particular the hypothesis of evolution by tumor neofunctionalization.

Research highlights

Earlier we described a new class of genes that are tumor-specifically expressed and evolutionarily novel (TSEEN). As the functions of TSEEN genes are often uncertain, we decided to study TSEEN genes of fishes so that we could trace the appearance of their new functions in higher vertebrates. We found that many human genes which are involved in development of progressive traits (placenta development, mammary gland and lung development etc.,) originated in fishes and are expressed in fish tumors.

Transcription factor 7 promotes the progression of perihilar cholangiocarcinoma by inducing the transcription of c-Myc and FOS-like antigen 1

Background

Perihilar cholangiocarcinoma (PHCC) is the most common type of cholangiocarcinoma with the worst prognosis. Radical resection of PHCC is difficult; thus, few effective biomarkers or useful molecular profiles for PHCC have been reported in recent years. Therefore, in this study, we aimed to assess biomarkers for PHCC.

Methods

We screened potential biomarkers for PHCC using exome and transcriptome sequencing with PHCC tissues and paired normal tissues. Transcription factor 7 (TCF7) expression was evaluated using quantitative reverse transcription polymerase chain reaction, western blotting, and immunohistochemistry. The correlations between TCF7 and clinicopathological factors were analyzed with Chi-square test, and the prognostic significance of TCF7 was evaluated with univariate and multivariate analyses. The functions of TCF7 and its main effectors in PHCC cells were investigated in vitro and in vivo.

Findings

TCF7 expression was upregulated in PHCC and was an unfavorable prognostic biomarker. c-Myc was a main effector of TCF7 in PHCC cells and modulated TCF7-induced proliferation, invasion, and migration. FOS-like antigen 1 (FOSL1) was identified as a downstream target of TCF7 and was required in TCF7-induced PHCC proliferation. Triple-positive expression of TCF7, c-Myc, and FOSL1 predicted a much worse prognosis in patients with PHCC than TCF7 expression alone.

Interpretation

Postoperative detection of TCF7, c-Myc, and FOSL1 may be useful for stratifying patients with a high risk of unfavorable prognosis, and suppressing TCF7 or its downstream effectors may be a promising strategy for the treatment of PHCC.

Expression of long non-coding RNA LINC00973 is consistently increased upon treatment of colon cancer cells with different chemotherapeutic drugs

Early prediction of tumor relapse depends on the identification of new prognostic cancer biomarkers, which are suitable for monitoring tumor response to different chemotherapeutic drugs. Using RNA-Seq, RT-qPCR, bioinformatics, and studies utilizing the murine tumor xenograft model, we have found significant and consistent changes in the abundance of five lincRNAs (LINC00973, LINC00941, CASC19, CCAT1, and BCAR4) upon treatment of both HT-29 and HCT-116 cells with 5-fluorouracil, oxaliplatin, and irinotecan at different doses and durations; both in vitro and in vivo. The most frequent changes were detected for LINC00973, whose content is most strongly and consistently increased upon treatment of both colon cancer cell lines with all three chemotherapeutic drugs. Additional studies are required in order to determine the molecular mechanisms by which anticancer drugs affect LINC00973 expression and to define the consequences of its upregulation on drug resistance of cancer cells.