Fig 2: CMTM6 and PD-L1 were found in the lysates of CC-derived cells. (a) CMTM6 expression was found to be higher in the total lysate of CaSki cells compared to those of HeLa and SiHa cells, shown as bands corresponding to the approximate molecular weight reported for CMTM6 and its densitometric analysis. (b) The bands corresponding to the molecular weight reported for PD-L1 were also found in the three cell lines, coinciding again to show that CaSki cells express the highest levels of this protein; the band pattern and its densitometric analysis are shown. In both cases, β-actin was used as a constitutive protein and loading control. The uncropped blots are shown in Figure S2. Data are shown as mean ± SD; three independent experiments were performed for each condition. * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001, **** p ≤ 0.0001, ns: no significance.

Fig 3: Total CMTM6 and total PD-L1 in plasma from the healthy donors (HDs) group and the cervical cancer patients (CC) group. (a) Concentrations of CMTM6 in the plasma of HDs (n = 23) and CC (n = 23) were measured by enzyme-linked immunosorbent assay (ELISA). Data are shown as pg/mL of CMTM6. (b) PD-L1 levels in the plasma of HDs (n = 11) and CC (n = 21) are shown as pg/mL of PD-L1. Student’s t-test was used. * p ≤ 0.05, ** p ≤ 0.01.

Fig 4: CMTM6 released by cell lines derived from cervical cancer. ELISA of culture supernatants to quantify the total levels of supernatant CMTM6. Detectable levels of supernatant CMTM6 were seen in all cell lines; however, HeLa cells were found to release the highest concentration (11,015 pg/mL). Data are shown as mean ± SD; two independent experiments were performed for each condition. * p < 0.05; *** p < 0.001; **** p < 0.0001.

Fig 5: CMTM6 and PD-L1 were found in exosomes from the plasma of the healthy donor group (HD) and the group of patients with cervical cancer (CC). (a) CMTM6 is preferentially released in exosomes in both the HD (n = 10) and CC (n = 20) groups; data shown as pg/mL of CMTM6. (b) PD-L1 was elevated in the exosome-enriched plasma fractions from both the HDs (n = 6) and CC (n = 15); data shown as pg/mL. (c) Correlation between exosomal CMTM6 and PD-L1 in HD samples (r = 0.996). (d) Correlation between exosomal CMTM6 and PD-L1 in CC samples (r = 0.8346). (e) CMTM6 was found to increase in the exosomal fractions from HDs and CC patients by Western blot. CD63 was used as an exosomal marker. The uncropped blots are shown in Figure S1. Wilcoxon ranked test was used. * p ≤ 0.05, ** p ≤ 0.01, *** p < 0.005.