Eubacterium sp. CAG:581 is clinically associated with NMIBC occurrence. To examine the potential relationship between the urinary microbiota alteration and NMIBC development, we firstly compared the long-read metagenomics sequencing data of 51 NMIBC patients and 47 healthy controls. LEfSe algorithm was used to define their potential differential bacterium patterns. We found Eubacterium sp. CAG:581, Bacteroides sp. 4_3_47FAA and Flavobacteriales were enriched in NMIBC group as compared to healthy control group (Fig. 1A). Flavobacteriales belong to the taxonomy level of class, hence we further studied Eubacterium sp. CAG:581 and Bacteroides sp. 4_3_47FAA for quantitative validation. The gut microbiota diversity of the above two groups was analyzed by the Chao1 index and Rank Abundance Curves for α diversity and Bray-Curtis distance and Binary-Jaccard distance for β diversity. It showed that α diversity of the urinary bacterial community of NMIBC group was lower than those of healthy control groups (Fig. 1B and 1C). β diversity of the urinary microbiota evaluated by ANOSIM was significantly different between the two groups based on the Bray-Curtis distances (R = 0.144, P = 0.025, Fig. 1D) and Binary-Jaccard distance (R2 = 0.190, P = 0.003, Fig. 1E). Then the difference in bacterial community composition was analyzed. At the phylum, class and genus level, the predominantly abundant phyla of the NMIBC group were Eubacterium sp. CAG:581, Bacteroides sp. 4_3_47FAA and Flavobacteriales, while the enriched phyla of the healthy control group were listed as the cyan columns in Fig. 1F.
The functional composition of the urinary microbiome was compared between NMIBC patients and controls by COG and KEGG pathway analyses. Although the functional compositions of the two groups were highly similar, COG analyses indicated the clustering of metabolic modules were increased in NMIBC group including the metabolism of xenobiotics by cytochrome P450 (E-value = 31.357, P < 0.001), purine (E-value = 30.835, P = 0.022), flavone and flavonol biosynthesis (E-value = 29.663, P = 0.029) (Fig. 1G). KEGG pathway analysis showed that these differential metabolisms were majorly concentrated on oxidative phosphorylation, cardiac muscle contraction and carbon metabolism (Fig. 1H). These findings are consistent with the hypermetabolic activity and aggressive characteristics of NMIBC.
Coculture of Eubacterium sp. CAG:581 promoted the growth of NMIBC organoids. Hypoxia is essential for the growth of obligate anaerobes, but prohibitive for the maintenance of viable tumor organoids [21]. To surmount this tradeoff in oxygen demands, we developed NMIBC organoids and anaerobes coculture system, consisting of a normoxic apical chamber and a hypoxic basal chamber. The plug inserts tightly, physically blocking the influx of external oxygen, which allows maintenance of hypoxia in the basal chamber, while oxygen freely perfuses the apical chamber (Fig. 2A). NMIBC organoids model derived from NMIBC patients were established on the array chip using 50% Matrigel. Each chip had a reservoir layer on the top, a 3D implanting hole in the middle, and anaerobes culture slide underneath. The nested design allowed convenient medium exchange without disruption of the 3D organoids (Fig. 2A). It showed that organoids size on the chip increased over time and achieved a diameter of 30 µm within 21 days. Eubacterium sp. CAG:581 and Bacteroides sp. 4_3_47FAA coculture groups respectively proliferated faster by 48.5% and 37.8% when compared with control NMIBC organoids on Day 21 (Fig. 2B). On day 21, bright-field images of Eubacterium sp. CAG:581 coculture group has presented heterogeneous morphologies with predominantly thin-walled cystic structure and solid dense structure (Fig. 2C). To gain insights into the underlying mechanisms, we randomly performed RNA-Seq to compare Eubacterium sp. CAG:581-cocultured NMIBC organoids (N14-N26) and control NMIBC organoids (N1-N13). It demonstrated that ECM1 and MMP9 were most significantly upregulated in Eubacterium sp. CAG:581-cocultured NMIBC organoids, while PTPN6 and IKZF3 were mostly downregulated in the heatmap and ssGSEA analysis (Fig. 2D and 2E), which should be further validated by molecular biological experiments.
Eubacterium sp. CAG:581 activated ECM1/ERK1/2 phosphorylation/MMP9 of NMIBC organoids. Based on the above RNA-Seq predictive data, we have determined the transcriptional levels of ptpn6, ikzf3, ecm1 and mmp9 in NMIBC organoids cocultured with Eubacterium sp. CAG:581 and control NMIBC organoids by RT-PCR. It showed that increased colony forming units (CFU) gradient (5×105, 106, 5×106, 107, 5×107) of Eubacterium sp. CAG:581 have significantly increased mRNA levels of ecm1 and mmp9 (Fig. 3A). Then we compared their protein expressions by the assay of western blotting, which also demonstrated increased gradient of Eubacterium sp. CAG:581 could upregulate ECM1 and MMP9 of NMIBC organoids as compared with the control organoids. It was reported that ECM1 induces tumor growth by promoting angiogenesis or enhancing the EGF signaling in the breast cancer [22]. We thus detected their expression of ERK1/2 phosphorylation and AKT phosphorylation, which manifested the upregulated ERK1/2 phosphorylation under the exposure of increased CFU gradient of Eubacterium sp. CAG:581 (Fig. 3B). Then we used shRNA of ECM1 to model BCa organoidshECM1 and control BCa organoidvector. When exposed to 107 cfu Eubacterium sp. CAG:581, BCa organoidshECM1 was determined with decreased expression of ERK1/2 phosphorylation and MMP9. Meanwhile, BCa organoidshECM1 and BCa organoidvector were treated with 10 µM Ravoxertinib (Rav) or Ulixertinib (Uli), both of which are inhibitors of ERK1/2 [23, 24]. It showed that both Rav and Uli could impair the expression of MMP9 (Fig. 3C). Lastly, we detected the proliferative size of Rav-treated or Uli-treated BCa organoidshECM1 and control BCa organoidvector under the exposure of 107 cfu Eubacterium sp. CAG:581 for 21 days. We found ERK1/2 inhibition or shECM1 could effectively prohibit the growth of BCa organoids (Fig. 3D), which suggested Eubacterium sp. CAG:581 progressed NMIBC organoids by activating ECM1/ERK1/2 phosphorylation/MMP9.
Eubacterium sp. CAG:581 was endowed with the diagnostic predictor for NMIBC. Increasing evidence points to the urinary microbiota as a possible key susceptibility factor for early-stage bladder cancer (BCa) progression [11, 25]. However, its conclusive interpretation is often insufficient, given that various environmental conditions could significantly alter the regulation of urinary microbiota. Herein we have evaluated the relationship between the amount of Eubacterium sp. CAG:581, ECM1, MMP9 and other baseline features in 51 NMIBC patients and 47 healthy controls (Fig. 4A). The amount of Eubacterium sp. CAG:581 was positively associated with the occurrence of NMIBC (HR: 4.21, 95% CI: 2.54–5.33, log-rank P < 0.001). The expression of ECM1 (HR: 1.87, 95% CI: 1.61–2.83, log-rank P = 0.005) and MMP9 (HR: 1.66, 95% CI: 1.49–1.88, log-rank P = 0.013) were substantially higher in NMIBC group than healthy control group. In contrast, age, sex, smoking status and alcohol consumption of this study were not statistically significant for Pearson correlation analysis (Fig. 4A). In addition, levels of Eubacterium sp. CAG:581, ECM1 and MMP9 with survival probability of NMIBC were also analyzed by Kaplan Meier Curve. The findings revealed that higher amount of Eubacterium sp. CAG:581 was strongly associated with decreased survival probability of NMIBC (Fig. 4B), and the survival time was also favorably linked with the expression of ECM1 and MMP9 (Figs. 4C and 4D). These above data implied the detection of Eubacterium sp. CAG:581 is effective at predicting the occurrence of NMIBC.
Identification of NMIBC occurrence-associated Eubacterium sp. CAG:581 in the larger population. To further validate whether Eubacterium sp. CAG:581 levels had a similar prediction value in a different and larger NMIBC patients’ population, we analyzed an additional cohort with 406 NMIBC patients as the Cohort 2. Using PCA cluster analysis with 398 normal healthy controls, we identified the ability of Eubacterium sp. CAG:581 to distinguish NMIBC urine from healthy control urine (Fig. 5A). LASSO regression analysis of Eubacterium sp. CAG:581-induced prognostic DEGs by RNA-Seq was also modeled to verify its fine cooperativity (Fig. 5B) and stable partial likelihood deviation from the minimum value (Fig. 5C). Based on the abundance of Eubacterium sp. CAG:581 levels, we have also divided them into the group of high risk and low risk, which demonstrated that the prognosis model is feasible in their survival predictions (Figs. 5D and 5E). The prognostic value of increased urine ECM1 and MMP9 were also stable and accurate in larger NMIBC cohort. Decreased PTPN6 and IKZF3 were determined in the Cohort 2 as well (Fig. 5F). The total survival rate was significantly worse (P < 0.001) in NMIBC patients with high amounts of Eubacterium sp. CAG:581, according to the Kaplan-Meier survival curve (Fig. 5G). Receiver operating characteristic (ROC) curve analysis was conducted to predict the potential CRC recurrence using 1-, 2-, and 3-year NMIBC occurrence and 3-year occurrence was demonstrated with the highest AUC value of 0.79. Youden Index was used to determine the optimal cut-off point of 3-year NMIBC occurrence as 10.3 (delta CT value) that provided the best balance between the sensitivity and the specificity of Eubacterium sp. CAG:581 to predict NMIBC occurrence (Fig. 5H). Therefore, the data in Cohort 2 not only confirm our observation in Cohort 1 but also define the potential value of the Eubacterium sp. CAG:581 signature in predicting NMIBC occurrence.