A human XPC protein interactome--a resource

Prospects and feasibility of synergistic therapy with radiotherapy, immunotherapy, and DNA methyltransferase inhibitors in non-small cell lung cancer

The morbidity and mortality of lung cancer are increasing, seriously threatening human health and life. Non-small cell lung cancer (NSCLC) has an insidious onset and is not easy to be diagnosed in its early stage. Distant metastasis often occurs and the prognosis is poor. Radiotherapy (RT) combined with immunotherapy, especially with immune checkpoint inhibitors (ICIs), has become the focus of research in NSCLC. The efficacy of immunoradiotherapy (iRT) is promising, but further optimization is necessary. DNA methylation has been involved in immune escape and radioresistance, and becomes a game changer in iRT. In this review, we focused on the regulation of DNA methylation on ICIs treatment resistance and radioresistance in NSCLC and elucidated the potential synergistic effects of DNA methyltransferases inhibitors (DNMTis) with iRT. Taken together, we outlined evidence suggesting that a combination of DNMTis, RT, and immunotherapy could be a promising treatment strategy to improve NSCLC outcomes.

Proteomic profiling reveals an association between ALDH and oxidative phosphorylation and DNA damage repair pathways in human colon adenocarcinoma stem cells

Several members of the aldehyde dehydrogenase (ALDH) family, especially ALDH1 isoenzymes, have been identified as biomarkers of cancer stem cells (CSCs), a small subpopulation of oncogenic cells with self-renewal and multipotency capability. Consistent with this contention, cell populations with high ALDH enzymatic activity exhibit greater carcinogenic potential. It has been reported that ALDH1, especially ALDH1A1, serves as a valuable biomarker for colon CSCs. However, the functional roles of ALDHs in CSCs and solid tumors of the colon tissue is not fully understood. The aim of the present study was to identify molecular signature associated with high ALDH activity in human colorectal adenocarcinoma (COLO320DM) cells by proteomics profiling. Aldefluor™ assay was performed to sort COLO320DM cells exhibiting high (ALDH^high) and low (ALDH^low) ALDH activity. Label-free quantitative proteomics analyses were conducted on these two cell populations. Proteomics profiling revealed a total of 229 differentially expressed proteins (DEPs) in ALDH^high relative to ALDH^low cells, of which 182 were down-regulated and 47 were up-regulated. In agreement with previous studies, ALDH1A1 appeared to be the principal ALDH isozyme contributing to the Aldefluor™ assay activity in COLO320DM cells. Ingenuity pathway analysis of the proteomic datasets indicated that DEPs were associated with mitochondrial dysfunction, sirtuin signaling, oxidative phosphorylation and nucleotide excision repair. Our proteomics study predicts that high ALDH1A1 activity may be involved in these cellular pathways to promote a metabolic switch and cellular survival of CSCs.

Xeroderma Pigmentosum C: A Valuable Tool to Decipher the Signaling Pathways in Skin Cancers

Xeroderma pigmentosum (XP) is a rare autosomal genodermatosis that manifests clinically with pronounced sensitivity to ultraviolet (UV) radiation and the high probability of the occurrence of different skin cancer types in XP patients. XP is mainly caused by mutations in XP-genes that are involved in the nucleotide excision repair (NER) pathway that functions in the removal of bulky DNA adducts. Besides, the aggregation of DNA lesions is a life-threatening event that might be a key for developing various mutations facilitating cancer appearance. One of the key players of NER is XPC that senses helical distortions found in damaged DNA. The majority of XPC gene mutations are nonsense, and some are missense leading either to the loss of XPC protein or to the expression of a truncated nonfunctional version. Given that no cure is yet available, XPC patients should be completely protected and isolated from all types of UV radiations (UVR). Although it is still poorly understood, the characterization of the proteomic signature of an XPC mutant is essential to identify mediators that could be targeted to prevent cancer development in XPC patients. Unraveling this proteomic signature is fundamental to decipher the signaling pathways affected by the loss of XPC expression following exposure to UVB radiation. In this review, we will focus on the signaling pathways disrupted in skin cancer, pathways modulating NER's function, including XPC, to disclose signaling pathways associated with XPC loss and skin cancer occurrence.

Bioinformatics and expression analysis of the Xeroderma Pigmentosum complementation group C (XPC) of Trypanosoma evansi in Trypanosoma cruzi cells

Nucleotide excision repair (NER) acts repairing damages in DNA, such as lesions caused by cisplatin. Xeroderma Pigmentosum complementation group C (XPC) protein is involved in recognition of global genome DNA damages during NER (GG-NER) and it has been studied in different organisms due to its importance in other cellular processes. In this work, we studied NER proteins in Trypanosoma cruzi and Trypanosoma evansi, parasites of humans and animals respectively. We performed three-dimensional models of XPC proteins from T. cruzi and T. evansi and observed few structural differences between these proteins. In our tests, insertion of XPC gene from T. evansi (TevXPC) in T. cruzi resulted in slower cell growth under normal conditions. After cisplatin treatment, T. cruzi overexpressing its own XPC gene (TcXPC) was able to recover cell division rates faster than T. cruzi expressing TevXPC gene. Based on these tests, it is suggested that TevXPC (being an exogenous protein in T. cruzi) interferes negatively in cellular processes where TcXPC (the endogenous protein) is involved. This probably occurred due interaction of TevXPC with some endogenous molecules or proteins from T.cruzi but incapacity of interaction with others. This reinforces the importance of correctly XPC functioning within the cell.

Timely upstream events regulating nucleotide excision repair by ubiquitin-proteasome system: ubiquitin guides the way

The ubiquitin-proteasome system (UPS) plays crucial roles in regulation of multiple DNA repair pathways, including nucleotide excision repair (NER), which eliminates a broad variety of helix-distorting DNA lesions that can otherwise cause deleterious mutations and genomic instability. In mammalian NER, DNA damage sensors, DDB and XPC acting in global genomic NER (GG-NER), and, CSB and RNAPII acting in transcription-coupled NER (TC-NER) sub-pathways, undergo an array of post-translational ubiquitination at the DNA lesion sites. Accumulating evidence indicates that ubiquitination orchestrates the productive assembly of NER preincision complex by driving well-timed compositional changes in DNA damage-assembled sensor complexes. Conversely, the deubiquitination is also intimately involved in regulating the damage sensing aftermath, via removal of degradative ubiquitin modification on XPC and CSB to prevent their proteolysis for the factor recycling. This review summaries the relevant research efforts and latest findings in our understanding of ubiquitin-mediated regulation of NER and active participation by new regulators of NER, e.g., Cullin-Ring ubiquitin ligases (CRLs), ubiquitin-specific proteases (USPs) and ubiquitin-dependent segregase, valosin-containing protein (VCP)/p97. We project hypothetical step-by-step models in which VCP/p97-mediated timely extraction of damage sensors is integral to overall productive NER. The USPs and proteasome subtly counteract in fine-tuning the vital stability and function of NER damage sensors.

Role of Mitochondria in Viral Infections

Viral diseases account for an increasing proportion of deaths worldwide. Viruses maneuver host cell machinery in an attempt to subvert the intracellular environment favorable for their replication. The mitochondrial network is highly susceptible to physiological and environmental insults, including viral infections. Viruses affect mitochondrial functions and impact mitochondrial metabolism, and innate immune signaling. Resurgence of host-virus interactions in recent literature emphasizes the key role of mitochondria and host metabolism on viral life processes. Mitochondrial dysfunction leads to damage of mitochondria that generate toxic compounds, importantly mitochondrial DNA, inducing systemic toxicity, leading to damage of multiple organs in the body. Mitochondrial dynamics and mitophagy are essential for the maintenance of mitochondrial quality control and homeostasis. Therefore, metabolic antagonists may be essential to gain a better understanding of viral diseases and develop effective antiviral therapeutics. This review briefly discusses how viruses exploit mitochondrial dynamics for virus proliferation and induce associated diseases.

Mass spectrometry-based protein‒protein interaction techniques and their applications in studies of DNA damage repair

Proteins are major functional units that are tightly connected to form complex and dynamic networks. These networks enable cells and organisms to operate properly and respond efficiently to environmental cues. Over the past decades, many biochemical methods have been developed to search for protein-binding partners in order to understand how protein networks are constructed and connected. At the same time, rapid development in proteomics and mass spectrometry (MS) techniques makes it possible to identify interacting proteins and build comprehensive protein‒protein interaction networks. The resulting interactomes and networks have proven informative in the investigation of biological functions, such as in the field of DNA damage repair. In recent years, a number of proteins involved in DNA damage response and DNA repair pathways have been uncovered with MS-based protein‒protein interaction studies. As the technologies for enriching associated proteins and MS become more sophisticated, the studies of protein‒protein interactions are entering a new era. In this review, we summarize the strategies and recent developments for exploring protein‒protein interaction. In addition, we discuss the application of these tools in the investigation of protein‒protein interaction networks involved in DNA damage response and DNA repair.

Emerging Roles of Post-Translational Modifications in Nucleotide Excision Repair

Nucleotide excision repair (NER) is a versatile DNA repair pathway which can be activated in response to a broad spectrum of UV-induced DNA damage, such as bulky adducts, including cyclobutane-pyrimidine dimers (CPDs) and 6–4 photoproducts (6–4PPs). Based on the genomic position of the lesion, two sub-pathways can be defined: (I) global genomic NER (GG-NER), involved in the ablation of damage throughout the whole genome regardless of the transcription activity of the damaged DNA locus, and (II) transcription-coupled NER (TC-NER), activated at DNA regions where RNAPII-mediated transcription takes place. These processes are tightly regulated by coordinated mechanisms, including post-translational modifications (PTMs). The fine-tuning modulation of the balance between the proteins, responsible for PTMs, is essential to maintain genome integrity and to prevent tumorigenesis. In this review, apart from the other substantial PTMs (SUMOylation, PARylation) related to NER, we principally focus on reversible ubiquitylation, which involves E3 ubiquitin ligase and deubiquitylase (DUB) enzymes responsible for the spatiotemporally precise regulation of NER.

OTUD4: A Potential Prognosis Biomarker for Multiple Human Cancers

Background

Deubiquitinase OTU domain containing 4 (OTUD4) is initially identified as a K48-specific deubiquitinase and plays an important role in DNA damage repair signaling transduction. However, the expression level, prognostic role, biological function and mechanism of OTUD4 in multiple human cancers are unclear.

Methods

GEPIA online (http://gepia.cancer-pku.cn/; The Cancer Genome Atlas (TCGA) database) was used to analyze the mRNA expression of OTUD4 in multiple human cancers. Kaplan-Meier plotter (KM plotter) database and TCGA database were used to evaluate the prognostic value of OTUD4 expression in multiple human cancers. MTT, Transwell and 3D culture assays were used to detect the role of OTUD4 in breast, liver and lung cancer cells. The correlation between OTUD4 and apoptosis signaling pathway and AKT signaling pathway was analyzed by Gene set enrichment analysis (GSEA).

Results

OTUD4 mRNA expression is significantly downregulated in multiple human cancer tissues. Survival analysis establishes that the downregulation of OTUD4 predicts poor prognosis in many solid tumors, including breast invasive carcinoma (BRCA), esophageal carcinoma (ESCA), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma (LUAD), and ovarian serous cystadenocarcinoma (OV). Furthermore, overexpression of OTUD4 could inhibit tumor cell proliferation, migration and invasion of breast, liver and lung cancer cells through inhibiting the AKT signaling pathway.

Conclusion

This study found that OTUD4 may be a potential predictive factor for several human cancers and a tumor suppressor for breast, liver and lung cancer. The overexpression of OTUD4 restrained proliferation, migration and invasion of human breast, liver and lung cancer cells through promoting cancer cells apoptosis and inhibiting AKT signaling pathway. Notably, our results indicated that OTUD4 could be a useful biomarker for the prognosis of human cancers and a potential molecular target for diagnosis and treatment of breast, liver and lung cancer.

Current Landscape of Epigenetics in Lung Cancer: Focus on the Mechanism and Application

Lung cancer is the leading cause of cancer-related mortality worldwide. Tumorigenesis involves a multistep process resulting from the interactions of genetic, epigenetic, and environmental factors. Genome-wide association studies and sequencing studies have identified many epigenetic alterations associated with the development of lung cancer. Epigenetic mechanisms, mainly including DNA methylation, histone modification, and noncoding RNAs (ncRNAs), are heritable and reversible modifications that are involved in some important biological processes and affect cancer hallmarks. We summarize the major epigenetic modifications in lung cancer, focusing on DNA methylation and ncRNAs, their roles in tumorigenesis, and their effects on key signaling pathways. In addition, we describe the clinical application of epigenetic biomarkers in the early diagnosis, prognosis prediction, and oncotherapy of lung cancer. Understanding the epigenetic regulation mechanism of lung cancer can provide a new explanation for tumorigenesis and a new target for the precise treatment of lung cancer.

OTU deubiquitinase 4 is silenced and radiosensitizes non-small cell lung cancer cells via inhibiting DNA repair

Background

Radiotherapy is becoming one major therapeutics for non-small cell lung cancer (NSCLC). Identifying novel radiosensitizers will greatly increase the efficacy of radiotherapy and benefit more patients. OTU deubiquitinase 4 (OTUD4) has been reported involved in DNA damage repair pathways and could be a potential target for chemotherapy therapy. This study aimed to investigate the roles of OTUD4 in regulation of radiosensitivity of NSCLC via modulating DNA repair.

Methods

The expression of OTUD4, γ-H2Ax and ATM/CHK2/p53 pathway-related signaling molecules were detected by Western blotting and QRT-PCR. The methylation of OTUD4 promoter was investigated by 5-aza-deoxycytidine treatment, methylation-specific PCR and bisulfite genomic sequencing assays. Radiosensitivity was assessed by the clonogenic formation assay. Cell cycle, cell apoptosis were analyzed by flow cytometry. DNA damage and repair were determined by comet assay, γ-H2Ax foci staining and flow cytometry.

Results

OTUD4 is dramatically downregulated in NSCLC and its downregulation significantly correlates with poor prognosis of NSCLC patients. Promoter hypermethylation is responsible for the loss of OTUD4 expression in NSCLC cells. Overexpression of OTUD4 increases radiosensitivity of NSCLC cells exhibiting as impaired clonogenic formation ability, enhanced cell cycle arrest and increased cell apoptosis. Moreover, molecular mechanism study reveals that OTUD4 radiosensitizs NSCLC cells via ATM/CHK2/P53 signaling and inhibiting homology-directed repair of DNA double strand breaks induced by ionizing radiation.

Conclusions

This study uncovers a tumor-suppressing role of OTUD4 and that OTUD4 is a potential radiosensitizer for NSCLC.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0816-z) contains supplementary material, which is available to authorized users.

Exploring novel key regulators in breast cancer network

The breast cancer network constructed from 70 experimentally verified genes is found to follow hierarchical scale free nature with heterogeneous modular organization and diverge leading hubs. The topological parameters (degree distributions, clustering co-efficient, connectivity and centralities) of this network obey fractal rules indicating absence of centrality lethality rule, and efficient communication among the components. From the network theoretical approach, we identified few key regulators out of large number of leading hubs, which are deeply rooted from top to down of the network, serve as backbone of the network, and possible target genes. However, p53, which is one of these key regulators, is found to be in low rank and keep itself at low profile but directly cross-talks with important genes BRCA2 and BRCA3. The popularity of these hubs gets changed in unpredictable way at various levels of organization thus showing disassortive nature. The local community paradigm approach in this network shows strong correlation of nodes in majority of modules/sub-modules (fast communication among nodes) and weak correlation of nodes only in few modules/sub-modules (slow communication among nodes) at various levels of network organization.

Timing of DNA lesion recognition: Ubiquitin signaling in the NER pathway

Damaged DNA is repaired by specialized repair factors that are recruited in a well-orchestrated manner to the damage site. The DNA damage response at UV inflicted DNA lesions is accompanied by posttranslational modifications of DNA repair factors and the chromatin environment sourrounding the lesion. In particular, mono- and poly-ubiquitylation events are an integral part of the DNA damage signaling. Whereas ubiquitin signaling at DNA doublestrand breaks has been subject to intensive studies comparatively little is known about the intricacies of ubiquitylation events occurring during nucleotide excision repair (NER), the major pathway to remove bulky helix lesions. Both, the global genomic (GG-NER) and the transcription-coupled (TC-NER) branches of NER are subject to ubiquitylation and deubiquitylation processes.Here we summarize our current knowledge of the ubiquitylation network that drives DNA repair in the NER pathway and we discuss the crosstalk of ubiquitin signaling with other prominent post-translational modfications that might be essential to time the DNA damage recognition step.

Nucleotide Excision Repair: Finely Tuned Molecular Orchestra of Early Pre-incision Events

Nucleotide excision repair (NER) eliminates a broad variety of helix-distorting DNA lesions that can otherwise cause genomic instability. NER comprises two distinct subpathways: global genomic NER (GG-NER) operating throughout the genome, and transcription-coupled NER (TC-NER) preferentially removing DNA lesions from transcribing DNA strands of transcriptionally active genes. Several NER factors undergo post-translational modifications, including ubiquitination, occurring swiftly and reversibly at DNA lesion sites. Accumulating evidence indicates that ubiquitination not only orchestrates the spatio-temporal recruitment of key protein factors to DNA lesion sites but also the productive assembly of NER pre-incision complex. This review will be restricted to the latest conceptual understanding of ubiquitin-mediated regulation of initial damage sensors of NER, that is DDB, XPC, RNAPII and CSB. We project hypothetical NER models in which ubiquitin-specific segregase, valosin-containing protein (VCP)/p97, plays an essential role in timely extraction of the congregated DNA damage sensors to functionally facilitate the DNA lesion elimination from the genome.

The emerging role of deubiquitination in nucleotide excision repair

Nucleotide excision repair (NER) protects genome stability by eliminating DNA helix distorting lesions, such as those induced by UV radiation. The addition and removal of ubiquitin, namely, ubiquitination and deubiquitination, have recently been demonstrated as general mechanisms to regulate protein functions. Accumulating evidence shows that several NER factors are subjected to extensive regulation by ubiquitination and deubiquitination. Thus, the balance between E3 ligases and deubiquitinating enzyme activities can dynamically alter the ubiquitin landscape at DNA damage sites, thereby regulating NER efficiency. Current knowledge about XPC ubiquitination by different ubiquitin E3 ligases highlights the importance of ubiquitin linkage types in regulating XPC binding and release from damaged DNA. Here, we discuss the emerging roles of deubiquitinating enzymes and their ubiquitin linkage specificities in NER.

Global-genome Nucleotide Excision Repair Controlled by Ubiquitin/Sumo Modifiers

Global-genome nucleotide excision repair (GG-NER) prevents genome instability by excising a wide range of different DNA base adducts and crosslinks induced by chemical carcinogens, ultraviolet (UV) light or intracellular side products of metabolism. As a versatile damage sensor, xeroderma pigmentosum group C (XPC) protein initiates this generic defense reaction by locating the damage and recruiting the subunits of a large lesion demarcation complex that, in turn, triggers the excision of aberrant DNA by endonucleases. In the very special case of a DNA repair response to UV radiation, the function of this XPC initiator is tightly controlled by the dual action of cullin-type CRL4(DDB2) and sumo-targeted RNF111 ubiquitin ligases. This twofold protein ubiquitination system promotes GG-NER reactions by spatially and temporally regulating the interaction of XPC protein with damaged DNA across the nucleosome landscape of chromatin. In the absence of either CRL4(DDB2) or RNF111, the DNA excision repair of UV lesions is inefficient, indicating that these two ubiquitin ligases play a critical role in mitigating the adverse biological effects of UV light in the exposed skin.

Xeroderma pigmentosum group C sensor: unprecedented recognition strategy and tight spatiotemporal regulation

The cellular defense system known as global-genome nucleotide excision repair (GG-NER) safeguards genome stability by eliminating a plethora of structurally unrelated DNA adducts inflicted by chemical carcinogens, ultraviolet (UV) radiation or endogenous metabolic by-products. Xeroderma pigmentosum group C (XPC) protein provides the promiscuous damage sensor that initiates this versatile NER reaction through the sequential recruitment of DNA helicases and endonucleases, which in turn recognize and excise insulting base adducts. As a DNA damage sensor, XPC protein is very unique in that it (a) displays an extremely wide substrate range, (b) localizes DNA lesions by an entirely indirect readout strategy, (c) recruits not only NER factors but also multiple repair players, (d) interacts avidly with undamaged DNA, (e) also interrogates nucleosome-wrapped DNA irrespective of chromatin compaction and (f) additionally functions beyond repair as a co-activator of RNA polymerase II-mediated transcription. Many recent reports highlighted the complexity of a post-translational circuit that uses polypeptide modifiers to regulate the spatiotemporal activity of this multiuse sensor during the UV damage response in human skin. A newly emerging concept is that stringent regulation of the diverse XPC functions is needed to prioritize DNA repair while avoiding the futile processing of undamaged genes or silent genomic sequences.

Architecture of the human XPC DNA repair and stem cell coactivator complex

The Xeroderma pigmentosum complementation group C (XPC) complex is a versatile factor involved in both nucleotide excision repair and transcriptional coactivation as a critical component of the NANOG, OCT4, and SOX2 pluripotency gene regulatory network. Here we present the structure of the human holo-XPC complex determined by single-particle electron microscopy to reveal a flexible, ear-shaped structure that undergoes localized loss of order upon DNA binding. We also determined the structure of the complete yeast homolog Rad4 holo-complex to find a similar overall architecture to the human complex, consistent with their shared DNA repair functions. Localized differences between these structures reflect an intriguing phylogenetic divergence in transcriptional capabilities that we present here. Having positioned the constituent subunits by tagging and deletion, we propose a model of key interaction interfaces that reveals the structural basis for this difference in functional conservation. Together, our findings establish a framework for understanding the structure-function relationships of the XPC complex in the interplay between transcription and DNA repair.

XPC: Going where no DNA damage sensor has gone before

XPC has long been considered instrumental in DNA damage recognition during global genome nucleotide excision repair (GG-NER). While this recognition is crucial for organismal health and survival, as XPC's recognition of lesions stimulates global genomic repair, more recent lines of research have uncovered many new non-canonical pathways in which XPC plays a role, such as base excision repair (BER), chromatin remodeling, cell signaling, proteolytic degradation, and cellular viability. Since the first discovery of its yeast homolog, Rad4, the involvement of XPC in cellular regulation has expanded considerably. Indeed, our understanding appears to barely scratch the surface of the incredible potential influence of XPC on maintaining proper cellular function. Here, we first review the canonical role of XPC in lesion recognition and then explore the new world of XPC function.

SUMO and ubiquitin-dependent XPC exchange drives nucleotide excision repair

XPC recognizes UV-induced DNA lesions and initiates their removal by nucleotide excision repair (NER). Damage recognition in NER is tightly controlled by ubiquitin and SUMO modifications. Recent studies have shown that the SUMO-targeted ubiquitin ligase RNF111 promotes K63-linked ubiquitylation of SUMOylated XPC after DNA damage. However, the exact regulatory function of these modifications in vivo remains elusive. Here we show that RNF111 is required for efficient repair of ultraviolet-induced DNA lesions. RNF111-mediated ubiquitylation promotes the release of XPC from damaged DNA after NER initiation, and is needed for stable incorporation of the NER endonucleases XPG and ERCC1/XPF. Our data suggest that RNF111, together with the CRL4(DDB2) ubiquitin ligase complex, is responsible for sequential XPC ubiquitylation, which regulates the recruitment and release of XPC and is crucial for efficient progression of the NER reaction, thereby providing an extra layer of quality control of NER.

The nucleotide excision repair protein XPC is essential for bulky DNA adducts to promote interleukin-6 expression via the activation of p38-SAPK

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants, and many are potent carcinogens. Benzo[a]pyrene (B[a]P), one of the best-studied PAHs, is metabolized ultimately to the genotoxin anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE). BPDE triggers stress responses linked to gene expression, cell death and survival. So far, the underlying mechanisms that initiate these signal transduction cascades are unknown. Here we show that BPDE-induced DNA damage is recognized by DNA damage sensor proteins to induce activation of the stress-activated protein kinase (SAPK) p38. Surprisingly, the classical DNA damage response, which involves the kinases ATM and ATR, is not involved in p38-SAPK activation by BPDE. Moreover, the induction of p38-SAPK phosphorylation also occurs in the absence of DNA strand breaks. Instead, increased phosphorylation of p38-SAPK requires the nucleotide excision repair (NER) and DNA damage sensor proteins XPC and mHR23B. Interestingly, other genotoxins such as cisplatin (CDDP), hydrogen peroxide and ultraviolet radiation also enhance XPC-dependent p38-SAPK phosphorylation. In contrast, anti-benzo[c]phenanthrene-3,4-dihydrodiol-1,2-epoxide, the DNA adducts of which are not properly recognized by NER, does not trigger p38-SAPK activation. As a downstream consequence, expression and secretion of the pro-inflammatory cytokine interleukin-6 is induced by BPDE and CDDP in vitro and by CDDP in the murine lung, and depends on XPC. In conclusion, we describe a novel pathway in which DNA damage recognition by NER proteins specifically leads to activation of p38-SAPK to promote inflammatory gene expression.