Infiltration of Immune Competent Cells into Primary Tumors and Their Surrounding Connective Tissues in Xenograft and Syngeneic Mouse Models

Ovarian cancer cells regulate their mitochondrial content and high mitochondrial content is associated with a poor prognosis

Most cancer patients ultimately die from the consequences of distant metastases. As metastasis formation consumes energy mitochondria play an important role during this process as they are the most important cellular organelle to synthesise the energy rich substrate ATP, which provides the necessary energy to enable distant metastasis formation. However, mitochondria are also important for the execution of apoptosis, a process which limits metastasis formation. We therefore wanted to investigate the mitochondrial content in ovarian cancer cells and link its presence to the patient's prognosis in order to analyse which of the two opposing functions of mitochondria dominates during the malignant progression of ovarian cancer. Monoclonal antibodies directed against different mitochondrial specific proteins, namely heat shock proteins 60 (HSP60), fumarase and succinic dehydrogenase, were used in immunohistochemistry in preliminary experiments to identify the antibody most suited to detect mitochondria in ovarian cancer cells in clinical tissue samples. The clearest staining pattern, which even delineated individual mitochondria, was seen with the anti-HSP60 antibody, which was used for the subsequent clinical study staining primary ovarian cancers (n = 155), borderline tumours (n = 24) and recurrent ovarian cancers (n = 26). The staining results were semi-quantitatively scored into three groups according to their mitochondrial content: low (n = 26), intermediate (n = 50) and high (n = 84). Survival analysis showed that high mitochondrial content correlated with a statistically significant overall reduced survival rate In addition to the clinical tissue samples, mitochondrial content was analysed in ovarian cancer cells grown in vitro (cell lines: OVCAR8, SKOV3, OVCAR3 and COV644) and in vivo in severe combined immunodeficiency (SCID) mice.In in vivo grown SKOV3 and OVCAR8 cells, the number of mitochondria positive cells was markedly down-regulated compared to the in vitro grown cells indicating that mitochondrial number is subject to regulatory processes. As high mitochondrial content is associated with a poor prognosis, the provision of high energy substrates by the mitochondria seems to be more important for metastasis formation than the inhibition of apoptotic cell death, which is also mediated by mitochondria. In vivo and in vitro grown human ovarian cancer cells showed that the mitochondrial content is highly adaptable to the growth condition of the cancer cells.

Dissecting the molecular profiling and tumor immune microenvironment of three subtypes of esophageal cancer

BACKGROUND

Great improvements have been made in the prognosis of esophageal cancer (ESCA) with the application of chemotherapy and immunotherapy. However, the majority of cases remain resistant to these regimens. Hence there is an urgent need to characterize the subtypes of ESCA with favorable survival outcome and drug responsiveness.

METHODS

We characterized the malignant cells of ESCA and explored their communication with immune cells using the Cellchat algorithm. The ligand-receptor interaction pairs were then used as inputting information to identify the subtypes of ESCA by unsupervised clustering analysis. Further investigation aimed to dissect the different patterns of tumor immune microenvironment (TIME), tumor mutation burden, immunotherapy responsiveness and drug sensitivity among the various subtypes of ESCA. A nomogram was also constructed to predict the survival rate of ESCA patients by conducting Cox regression and decision curve analysis.

RESULTS

Three subtypes were identified based on the ligand-receptor interaction pairs. Patients in cluster 2 showed a longer survival time and less likelihood of response to immunotherapy compared with cluster 1 or 3. Eight hub genes were screened to construct a prognostic signature, which can stratify patients well into high- and low-risk groups with distinct survival outcomes and drug sensitivities. The nomogram showed quite good performance in predicting patient survival rates of 1 and 3 years.

CONCLUSION

This study characterized the molecular profiling and TIME patterns of three subtypes of ESCA. The relative findings will provide emergent insights for the treatment of ESCA.