The generation of reducing equivalent NADPH via glucose-6-phosphate dehydrogenase (G6PD) is critical for the maintenance of redox homeostasis and reductive biosynthesis in cells. NADPH also plays key roles in cellular processes mediated by redox signaling. Insufficient G6PD activity predisposes cells to growth retardation and demise. Severely lacking G6PD impairs embryonic development and delays organismal growth. Altered G6PD activity is associated with pathophysiology, such as autophagy, insulin resistance, infection, inflammation, as well as diabetes and hypertension. Aberrant activation of G6PD leads to enhanced cell proliferation and adaptation in many types of cancers. The present review aims to update the existing knowledge concerning G6PD and emphasizes how G6PD modulates redox signaling and affects cell survival and demise, particularly in diseases such as cancer. Exploiting G6PD as a potential drug target against cancer is also discussed.

Glucose-6-phosphate dehydrogenase (G6PD) is the rate-limiting enzyme of the pentose phosphate pathway that modulates cellular redox homeostasis via the regeneration of NADPH. G6PD-deficient cells have a reduced ability to induce the innate immune response, thus increasing host susceptibility to pathogen infections. An important part of the immune response is the activation of the inflammasome. G6PD-deficient peripheral blood mononuclear cells (PBMCs) from patients and human monocytic (THP-1) cells were used as models to investigate whether G6PD modulates inflammasome activation. A decreased expression of IL-1β was observed in both G6PD-deficient PBMCs and PMA-primed G6PD-knockdown (G6PD-kd) THP-1 cells upon lipopolysaccharide (LPS)/adenosine triphosphate (ATP) or LPS/nigericin stimulation. The pro-IL-1β expression of THP-1 cells was decreased by G6PD knockdown at the transcriptional and translational levels in an investigation of the expression of the inflammasome subunits. The phosphorylation of p38 MAPK and downstream c-Fos expression were decreased upon G6PD knockdown, accompanied by decreased AP-1 translocation into the nucleus. Impaired inflammasome activation in G6PD-kd THP-1 cells was mediated by a decrease in the production of reactive oxygen species (ROS) by NOX signaling, while treatment with hydrogen peroxide (H 2 O 2 ) enhanced inflammasome activation in G6PD-kd THP-1 cells. G6PD knockdown decreased Staphylococcus aureus and Escherichia coli clearance in G6PD-kd THP-1 cells and G6PD-deficient PBMCs following inflammasome activation. These findings support the notion that enhanced pathogen susceptibility in G6PD deficiency is, in part, due to an altered redox signaling, which adversely affects inflammasome activation and the bactericidal response.Abbreviations: G6PD, glucose-6-phosphate dehydrogenase; NADPH, reduced form of nicotinamide adenine dinucleotide phosphate; NOX, NADPH oxidase; NO, nitric oxide; NOS, nitric oxide synthase; UP-LPS, ultrapure lipopolysaccharide; PMA, phorbol 12-myristate 13-acetate; ATP, adenosine triphosphate; MAPK, mitogenactivated protein kinases; AP-1, activator protein 1; ROS, reactive oxygen species; PBMC, peripheral blood mononuclear cells; H 2 O 2 , hydrogen peroxide; THP-1, human monocytic cells; G6PD-kd, G6PD knockdown

Patients with oral cavity squamous cell carcinoma (OSCC) are frequently first diagnosed at an advanced stage, leading to poor prognosis and high mortality rates. Early detection of OSCC using body fluid-accessible biomarkers may improve the prognosis and survival rate of OSCC patients. As tumor interstitial fluid is a proximal fluid enriched with cancer-related proteins, it is a useful reservoir suitable for the discovery of cancer biomarkers and dysregulated biological pathways in tumor microenvironments. Thus, paired interstitial fluids of tumor (TIF) and adjacent noncancerous (NIF) tissues from 10 OSCC patients were harvested and analyzed using one-dimensional gel electrophoresis coupled with liquid chromatography-tandem mass spectrometry (GeLC-MS/MS). Using label-free spectral counting-based quantification, 113 proteins were found to be up-regulated in the TIFs compared with the NIFs. The gene set enrichment analysis (GSEA) revealed that the differentially expressed TIF proteins were highly associated with aminoacyl tRNA biosynthesis pathway. The elevated levels of 4 proteins (IARS, KARS, WARS, and YARS) involved in the aminoacyl tRNA biosynthesis were verified in the OSCC tissues with immunohistochemistry (IHC). In addition, nidogen-1 (NID1) was selected for verification as an OSCC biomarker. Salivary level of NID1 in OSCC patients (n = 48) was significantly higher than that in the healthy individuals (n = 51) and subjects with oral potentially malignant disorder (OPMD; n = 53). IHC analysis showed that NID1 level in OSCC tissues was increased compared with adjacent noncancerous epithelium (n = 222). Importantly, the elevated NID1 level was correlated with the advanced stages of OSCC, as well as the poor survival of OSCC patients. Collectively, the results suggested that TIF analysis facilitates understanding of the OSCC microenvironment and that salivary NID1 may be a useful biomarker for OSCC.

Background and objectives Human papillomavirus (HPV)-driven oropharyngeal squamous cell carcinoma (OPSCC) is increasing globally. In Taiwan, HPV-positive OPSCC is obscured by tobacco, alcohol, and betel quid use. We investigated the role of high-risk HPV (hrHPV) in a large retrospective Taiwan OPSCC cohort. Methods and results The cohort of 541 OPSCCs treated at Chang Gung Memorial Hospital from 1998–2016 consisted of 507 men (94%) and 34 women (6%). Most used tobacco (81%), alcohol (51%), and betel quid (65%). Formalin-fixed, paraffin-embedded tissue was used for p16 staining (a surrogate marker for HPV) and testing for HPV DNA presence and type by Multiplex HPV PCR-MassArray. HPV DNA and/or p16 staining (HPV-positive) was found in 28.4% (150/528) tumors. p16 and HPV DNA were strongly correlated (F < 0.0001). HPV16 was present in 82.8%, and HPV58 in 7.5% of HPV-positive tumors. HPV was associated with higher age (55.5 vs. 52.7 years, p = 0.004), lower T-stage (p = 0.008) better overall survival (OS) (hazard ratio [HR] 0.58 [95% CI 0.42–0.81], p = 0.001), and disease-free survival (DFS) (HR 0.54 [95% CI 0.40–0.73], p < 0.0001). Alcohol was strongly associated with recurrence and death (OS: HR 2.06 [95% CI 1.54–2.74], p < 0.0001; DFS: HR 1.72 [95% CI 1.33–2.24], p < 0.0001). OS and DFS in HPV-positive cases decreased for alcohol users (p < 0.0001). Obscured by the strong alcohol effect, predictive associations were not found for tobacco or betel quid. Conclusions As with HPV-positive OPSCC globally, HPV is an increasingly important etiological factor in Taiwanese OPSCC. HPV-positive OPSCC has considerable survival benefit, but this is reduced by alcohol, tobacco, and betel quid use. hrHPV is a cancer risk factor in males and females. Vaccinating both sexes with a multivalent vaccine including HPV58, combined with alcohol and tobacco cessation policies will be effective cancer-prevention public health strategies in Taiwan.

Background In North America and Western Europe, human papillomavirus (HPV)-driven oropharyngeal squamous cell carcinoma (OPSCC) has increased dramatically over the past 40 years, whereas HPV-negative OPSCC, typically associated with alcohol and tobacco as etiological factors, has declined. In Taiwan, the OPSCC rate is increasing; however, there is limited understanding of the role of HPV, as tobacco, alcohol, and betel quid use are still very prominent. Here we investigated the involvement of HPV and its prognostic implications for OPSCC in Taiwan. Methods and findings We studied a retrospective cohort of 541 OPSCCs undergoing care between 1998 and 2016 at the Chang Gung Memorial Hospital-Linkou, Taiwan. Clinical and risk exposure data were retrieved from hospital charts. Most cases were males (94%) and had concomitant (87%) exposure to alcohol (51%), tobacco (83%), and betel quid (65%). Formalin-fixed, paraffin-embedded tissue sections were immunostained for p16, a surrogate for active HPV, and DNA was tested for HPV detection and genotyping by Multiplex PCR-MassArray. Tumors with p16 and/or HPV DNA positivity were identified as HPV-positive. HPV status was assigned to 528 tumors. The prevalence of HPV-positive OPSCC was 28.4% (150/528), with a strong correlation between p16 and HPV DNA results (F < 0.0001). We observed an incremental trend for HPV-positive OPSCC over 18 years. HPV16 alone was found in 76.9%, and HPV58 in 7.5% tumors. Among males more tumors were HPV-negative than positive, but among the 34 females more tumors were HPV-positive (62% vs. 38%, p < 0.0001), more commonly from the tonsils (p < 0.01), and less prone to use tobacco, alcohol, and betel quid (p < 0.0001). For all patients, HPV-positive OPSCC was associated with higher age at diagnosis (55.5 vs. 52.7 years, p = 0.004), and lower T-stage (p = 0.02). HPV-positivity in OPSCC tumors was an independent predictor of better overall survival (OS) (hazard ratio [HR] 0.57 [95% CI 0.41-0.80], p = 0.0009), and disease-free survival (DFS) (HR 0.53 [95% CI 0.40-0.72], p < 0.0001) in multivariable estimations for up to 5-year post-diagnosis. Alcohol consumption was strongly associated with higher risk of recurrence and death (OS: HR 2.02 [95% CI 1.52-2.68], p < 0.0001; DFS: HR 1.70 [95% CI 1.31-2.21], p < 0.0001). No predictive associations were found for smoke or betel quid. Kaplan-Meier's OS and DFS were longer in HPV-positive cases (p < 0.0001), but this advantage decreased for alcohol users (p < 0.0001). Lastly, HPV-positive OPSCC had the best outcomes in non-drinkers, non-smokers, and non-betel quid chewers, but the prognostic benefit of HPV persisted in the presence of these risk factors. Conclusions Consistent with the increasing role of HPV on OPSCC globally, HPV is an important etiological factor in more than one-fourth of OPSCC cases from Chang Gung Hospital. Like in Western countries, HPV provides considerable independent survival benefits to OPSCC, but the added prognostic value is reduced by exposure to the risk factors, alcohol, smoking, and betel quid. There is a need to consider HPV as an etiologic factor in treatment and in cancer-prevention policies in Taiwan.