BACKGROUND
Hormone-dependent cancers, including breast, endometrial and ovarian cancers, account for 25% of all cancers in women. Endometrial cancer is the fifth most common cancer. Ovarian cancer is less common, but has a worse prognosis and higher mortality.
Estrogens are steroid hormones that regulate cell growth, proliferation and the physiology of reproductive processes and are also involved in the pathophysiology of cancer. Estrogens effects are caused by the activation of ERα and ERβ, which trigger the transcription of target genes, while the non-genomic effects are caused by interaction with the membrane-bound ER and by binding to the GPER receptor.
Enzymes from the aldo-keto reductase (AKR) protein superfamily are involved in many important biochemical processes, including the biosynthesis, metabolism and detoxification of endogenous and exogenous compounds. AKR1C3, AKR1B1 and AKR1B10 enzymes play an important role in hormone-dependent cancers. Among other, these three enzymes regulate cell proliferation, differentiation, and are involved in metabolism and resistance to chemotherapeutic agents, as well as in the metabolism of steroid hormones.
We investigated whether the enzymes AKR1C3, AKR1B1 and AKR1B10 and receptors ERα, ERβ and GPER are prognostic biochemical markers for estimating the course of the disease and the probability of developing resistance to individual chemotherapeutic agents.
METHODS
In study we included 233 patients who were treated for ovarian cancer or endometrial cancer. We performed immunohistochemical staining on paraffin-embedded cancerous tissue samples using validated antibodies according to optimized protocols and analyzed the presence of selected proteins AKR1C3, AKR1B1, AKR1B10, ERα, ERβ and GPER. We evaluated the proportion, pattern and intensity of staining. Statistical methods were used to check possible correlations between the expression of the studied proteins with survival and with other clinical and pathological data. We additionally analyzed the expression data for ERα, ERβ and GPER at the RNA level (RNA-Seq normalized in series) and protein-level expression data (reverse-phase protein microarrays) from the open access database Portal cBioPortal (
https://www.cbioportal.org/).
RESULTS
Endometrial cancer
In patients with endometrial cancer, we detected a significantly higher expression of AKR1C3, AKR1B1 and AKR1B10 in the adjacent non-neoplastic endometrium compared to endometrioid endometrial cancer. Survival analysis in patients with endometrioid endometrial cancer showed that high expression of AKR1C3 and expression of AKR1B1 and AKR1B10 above the median value correlates with better overall survival and disease-free survival.
When analyzing estrogen receptors, we found that nuclear immunoreactivity for ERα in is weaker in endometrial cancer compared to control endometrial tissue; there were no differences in the cytoplasm. For ERβ, nuclear and cytoplasmic immunoreactivity was unchanged in cancer tissue compared to control tissue. GPER immunoreactivity was unchanged in cancer and control endometrial tissue. Survival analysis showed a trend for longer survival in patients with endometrioid endometrial cancer with higher ERα levels. In patients with endometrial cancer (type 1 and type 2), statistically significant longer survival was found in patients with a higher level of ERα and higher expression of the ESR1 and GPER genes, while the expression of the ESR2 gene had no effect on survival. Expression of ESR1, ESR2 and GPER genes and ERα protein had no statistically significant effect on disease free survival.
Ovarian cancer
In patients with ovarian cancer, there was no correlation between AKR1C3 expression and overall or disease-free survival or response to chemotherapy. A higher immunohistochemical level of AKR1B1 was associated with better overall survival and disease-free survival in patients with high-grade serous ovarian cancer, whereas AKR1B10 level showed no significant differences. We did not detect an association between AKR1B1 and AKR1B10 with different responses to chemotherapy. Survival analysis showed that in patients with high-grade serous ovarian cancer, there was no statistically significant association between overall survival and high or low expression levels of ESR1, ESR2 and GPER genes or ERα protein. ESR2 gene expression above the median in high-grade serous ovarian cancer was associated with longer disease-free survival, whereas ESR1 and GPER gene expression did not affect disease free survival.
CONCLUSION
With the results of the doctoral dissertation, we contributed to better understanding of the pathophysiology of endometrial and ovarian cancer. We determined the expression of estrogen receptors and were the first to characterize the aldo-keto-reductases AKR1C3, AKR1B1 and AKR1B10 in a large number of endometrial and ovarian cancer samples. In both malignant diseases, we showed the connection of aldo-keto-reductases with pathogenesis and described the association of different levels of the studied proteins with survival. With our results, we identified biochemical markers with prognostic potential, which opens up possibilities for future studies and possible translation into clinical practice.
