Subcellular localization of hTERT in breast cancer: insights into its tumorigenesis and drug resistance mechanisms in HER2-immunopositive breast cancer.

Human telomerase reverse transcriptase (hTERT) is highly expressed in various cancers, including breast cancer. Although telomere elongation is an essential role for hTERT, the nuclear export after oxdative stress has also been shown in several cancer cell lines and is associated with drug-resistance in vitro. As only a few reports focused on the subcellular localization of hTERT in clinical specimens, we performed immunohistochemistry (IHC) and analyzed the correlation between intracellular hTERT expression and the clinicopathological characteristics to identify the clinical significance of hTERT subcellular expression in breast cancers. 144 invasive breast cancers classified by IHC subtype without primary systemic therapy (PST), were selected from a surgical resection cohort and were immunostained for hTERT, p-STAT3, p-AKT and p-ERK. The nuclear and/or cytoplasmic staining intensity and proportion of hTERT were scored and compared with clinicopathological parameters. The nuclear hTERT expression was significantly correlated with HER2 expression (p = 0.00156), and the scores were significantly correlated with p-STAT3 and p-AKT expression scores (r = 0.532, p = 0.000587 and r = 0.345, p = 0.0339, respectively) in the HER2-immunopositive breast cancer including luminal-HER2 and HER2 subtypes. Furthermore, hTERT was expressed more in cytoplasm in the specimens after PST than those before PST, and the score tended to be negatively correlated with tumor shrinkage rate in HER2 subtype (r = -0.593, p = 0.0705). These results suggest that nuclear and/or cytoplasmic hTERT may play a different role before and after PST including the tumorigenesis and drug-resistance in breast cancer. Suppression of cytoplasmic hTERT expression may lead to more effective strategy for drug-resistant HER2 subtype in breast cancer.

Cyclin-dependent kinase 4 upregulation mediates acquired resistance of dabrafenib plus trametinib in BRAF V600E-mutated lung cancer.

BACKGROUND: Combination therapy with the B-Raf inhibitor, dabrafenib, and the MEK inhibitor, trametinib (DT) is commonly used to treat patients with B-Raf proto-oncogene, serine/threonine kinase V600E (BRAF V600E)-mutated non-small cell lung cancer (NSCLC). However, the mechanisms through which cancer develops DT resistance are unclear. Here, we investigated new mechanisms underlying acquired DT-resistant NSCLC with the BRAF V600E mutation. METHODS: We compared genomic signatures before and after DT treatment in patients with NSCLC. RESULTS: Two of four patients treated with DT developed carcinomatous pleuritis within 3 months. Target DNA sequencing and quantitative polymerase chain reaction (PCR) analyses revealed the increased expression level of cyclin-dependent kinase 4 (CDK4). We also found prominent protein expression of CDK4 after DT treatment. Induction of CDK4 expression in a cell line derived from a patient with the BRAF V600E mutation resulted in partial resistance to dabrafenib. CONCLUSIONS: Our findings suggest a possible relationship between CDK4 upregulation and acquired resistance to DT therapy.

The value and practical utility of intraoperative touch imprint cytology of sentinel lymph node(s) in patients with breast cancer: A retrospective cytology-histology correlation study.

OBJECTIVE: Intraoperative evaluation of sentinel lymph nodes (SLNs) for patients with breast cancer is widely performed with frozen section (FS), cytology, or a combination of both. Touch imprint cytology (TIC) reportedly has an equivalent sensitivity to FS. We studied its diagnostic utility to detect SLN metastases. MATERIALS AND METHODS: Cases of 367 patients with breast cancer who underwent intraoperative valuation of SLNs (507 LNs) were evaluated. All FS and corresponding TIC slides of SLNs of each case were reviewed microscopically for the presence of metastases of any size. If present, the metastatic focus was measured on the FS. RESULTS: Of these 507 SLNs, 82 LNs (16.2%) from 69 women were found to have metastases in the FS and consisted of 5 LNs of isolated tumor cells, 15 of micrometastasis, and 62 of macrometastasis. TIC identified metastases in 69 of these 82 SLNs (sensitivity: 84.1%, specificity: 100%, and accuracy: 97.4%). All macrometastases could be detected by TIC, whereas TIC identified approximately 50% of micrometastases and none of isolated tumor cells. The size detection limit of metastatic foci, defined as the smallest dimension of metastasis detected without false negatives, was 2 mm. The smallest metastatic focus identified was 0.8 mm. CONCLUSIONS: TIC of SLNs is of great use given its negative predictive value of 100% for identification of macrometastasis in our study. For intraoperative evaluation of SLNs, based on our data, a practical two-step approach is proposed: SLN evaluation should be initially performed by TIC and then proceed to FS histological analysis only when cytologically positive to determine the size of metastatic focus.

PD-L1-specific helper T-cells exhibit effective antitumor responses: new strategy of cancer immunotherapy targeting PD-L1 in head and neck squamous cell carcinoma.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) originates from squamous epithelium of the upper aerodigestive tract and is the most common malignancy in the head and neck region. Among HNSCCs, oropharynx squamous cell carcinoma (OSCC) has a unique profile and is associated with human papillomavirus infection. Recently, anti-programmed cell death-1 monoclonal antibody has yielded good clinical responses in recurrent and/or metastatic HNSCC patients. Therefore, programmed death-ligand 1 (PD-L1) may be a favorable target molecule for cancer immunotherapy. Although PD-L1-expressing malignant cells could be targeted by PD-L1-specific CD8+ cytotoxic T lymphocytes, it remains unclear whether CD4+ helper T lymphocytes (HTLs) recognize and kill tumor cells in a PD-L1-specific manner. METHODS: The expression levels of PD-L1 and HLA-DR were evaluated using immunohistochemical analyses. MHC class II-binding peptides for PD-L1 were designed based on computer algorithm analyses and added into in vitro culture of HTLs with antigen-presenting cells to evaluate their stimulatory activity. RESULTS: We found that seven of 24 cases of OSCC showed positive for both PD-L1 and HLA-DR and that PD-L1241-265 peptide efficiently activates HTLs, which showed not only cytokine production but also cytotoxicity against tumor cells in a PD-L1-dependent manner. Also, an adoptive transfer of the PD-L1-specific HTLs significantly inhibited growth of PD-L1-expressing human tumor cell lines in an immunodeficient mouse model. Importantly, T cell responses specific for the PD-L1241-265 peptide were detected in the HNSCC patients. CONCLUSIONS: The cancer immunotherapy targeting PD-L1 as a helper T-cell antigen would be a rational strategy for HNSCC patients.

Programmed death-ligand 1 and its soluble form are highly expressed in nasal natural killer/T-cell lymphoma: a potential rationale for immunotherapy.

Nasal natural killer/T-cell lymphoma (NNKTL) is an aggressive neoplasm with poor therapeutic responses and prognosis. The programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) pathway plays an important role in immune evasion of tumor cells through T-cell exhaustion. The aim of the present study was to examine the expression of PD-L1 and PD-1 molecules in NNKTL. We detected the expression of PD-L1 in biopsy samples from all of the NNKTL patients studied. PD-L1 was found on both malignant cells and tumor-infiltrating macrophages, while PD-1-positive mononuclear cells infiltrated the tumor tissues in 36% of patients. Most significantly, soluble PD-L1 (sPD-L1) was present in sera of NNKTL patients at higher levels as compared to healthy individuals and the levels of serum sPD-L1 in patients positively correlated with the expression of PD-L1 in lymphoma cells of tumor tissues. In addition, the high-sPD-L1 group of patients showed significantly worse prognosis than the low-sPD-L1 group. Furthermore, we confirmed that membrane and soluble PD-L1 was expressed on the surface and in the culture supernatant, respectively, of NNKTL cell lines. The expression of PD-L1 was observed in tumor tissues and sera from a murine xenograft model inoculated with an NNKTL cell line. Our results suggest that sPD-L1 could be a prognostic predictor for NNKTL and open up the possibility of immunotherapy of this lymphoma using PD-1/PD-L1 axis inhibitors.