Calreticulin Expression in Human Non–Small Cell Lung Cancers Correlates with Increased Accumulation of Antitumor Immune Cells and Favorable Prognosis

Abstract

A high density of tumor-infiltrating mature dendritic cells (DC) and CD8þ T cells correlates with a positive prognosis in a majority of human cancers. The recruitment of activated lymphocytes to the tumor microenvironment, primed to recognize tumor-associated antigens, can occur in response to immunogenic cell death (ICD) of tumor cells. ICD is characterized by the preapoptotic translocation of calreticulin (CRT) from the endoplasmic reticulum (ER) to the cell surface as a result of an ER stress response accompanied by the phosphorylation of eukaryotic initiation factor 2a (eIF2a). We conducted a retrospective study on two independent cohorts of patients with non-small cell lung cancer (NSCLC) to investigate the prognostic potential of CRT. We report that the level of CRT expression on tumor cells, which correlated with eIF2a phosphorylation, positively influenced the clinical outcome of NSCLC. High CRT expression on tumor cells was associated with a higher density of infiltrating mature DC and effector memory T-cell subsets, suggesting that CRT triggers the activation of adaptive immune responses in the tumor microenvironment. Accordingly, patients with elevated CRT expression and dense intratumoral infiltration by DC or CD8 þ T lymphocytes had the best prognosis. We conclude that CRT expression constitutes a new powerful prognostic biomarker that reflects enhanced local antitumor immune responses in the lung.

The ratio of CD8+/FOXP3 T lymphocytes infiltrating breast tissues predicts the relapse of ductal carcinoma in situ

“…17,[27][28][29] Antigen retrieval was performed by incubating slides in citrate buffer (pH 7.3) for 20 min at 98 C and cooling them for 30 min, at room temperature (RT). The sections were mounted on Shandon Sequenza coverplates (Thermo Fisher Scientific, 72-199-50) in distilled water.…”

Calreticulin exposure by malignant blasts correlates with robust anticancer immunity and improved clinical outcome in AML patients

“…21 In particular, CRT levels or exposure has been shown to convey robust prognostic information in subjects with multiple solid tumors, including neuroblastoma, non-small cell lung carcinoma, ovarian cancer, and colorectal carcinoma. [22][23][24][25] However, little is known on the prognostic value of CRT in patients with hematological malignancies, irrespective of the fact that these patients often receive ICD inducers, including anthracyclines and bortezomib. In a preliminary study, we reported that malignant blasts from patients with acute myeloid leukemia (AML) may expose CRT on the plasma membrane regardless of chemotherapy, 26 but did not investigate the prognostic relevance of these findings.…”

Biomarkers of immunogenic stress in metastases from melanoma patients: Correlations with the immune infiltrate

“…There are two striking differences between our prior work (on primary breast and lung cancer samples) and the present study (on melanoma metastases), although all these cancer types appear to be under strong immunosurveillance, meaning that the presence of an immune infiltrate and, more so, favorable ratios between immune effectors and immunosuppressive cell types predict improved OS. 21,31,[33][34][35][36][37][38][39]28 First, none of the malignant cell stress-related biomarkers had any impact on melanoma patient survival, contrasting with the observation that the presence of LC3B puncta and high expression of HMGB1 has a positive effect on the life expectancy of breast cancer patients. 23 This discrepancy might be related to the stage of patients (operable breast cancer vs. stage III/IV melanoma), intrinsic biological differences between neoplasias (perhaps related to the epithelial vs. neuroectodermal origin of these tumor types), or a rather distinct organization of the immunosurveillance system.…”

“…23,25 Reduced expression of CALR by cancer cells has been correlated with poor prognosis and reduced infiltration by CTL in colorectal cancer, 26 as well as in non-small cell lung cancer (NSCLC). 27,28 Similarly, low phosphorylation of eIF2a, which can be measured by immunohistochemistry using a phospho-neoepitope-specific antibody, predicts poor local immune responses and dismal prognosis in NSCLC. 28 In breast cancer, eIF2a phosphorylation could be associated with an increased ploidy (which induces ER stress and correlates with an increase in nuclear size) and the CD8 C…”

“…27,28 Similarly, low phosphorylation of eIF2a, which can be measured by immunohistochemistry using a phospho-neoepitope-specific antibody, predicts poor local immune responses and dismal prognosis in NSCLC. 28 In breast cancer, eIF2a phosphorylation could be associated with an increased ploidy (which induces ER stress and correlates with an increase in nuclear size) and the CD8 C…”