Fusion expression, purification, and characterization of cytokeratin 19 fragments in E. coli for enhanced stability in diagnostic applications.

Cytokeratin 19 fragment (CYFRA21-1) serves as a crucial tumor marker in the context of lung cancer patients, playing a pivotal role as a calibrator in the realm of in vitro diagnostics. Nevertheless, during practical application, it has come to light that the recombinantly synthesized full-length CYFRA21-1 antigen exhibits suboptimal stability at the requisite concentration, while the utilization of natural antigens incurs a substantial cost. To address this issue, our investigation harnessed a strategic approach whereby the soluble fragment of cytokeratin 19 (Aa244-400) was integrated into the pET32a vector, subsequently being expressed within E. coli through a fusion with the TrxA protein. This process involved induction of protein expression through 0.2 mM IPTG at 16 °C for a duration of 16 h. After induction, the target protein was purified through Ni affinity and ion exchange chromatography. Subsequent characterization of the targeted protein was executed through the SEC-HPLC technique. The attained CYFRA21-1 antigen, as generated within this study, was effectively incorporated into a chemiluminescence-based in vitro diagnostic detection kit. The results indicate that the fusion protein exhibited commendable reactivity and stability, manifesting a deviation of less than 10 % following incubation at 37 °C for 7 days. Importantly, the production yield achieved a notable magnitude of 300 mg/L, thus rendering it a cost-effective and scalable alternative to natural antigens for clinical diagnostic applications.

DNA methylation-associated allelic inactivation regulates Keratin 19 gene expression during pancreatic development and carcinogenesis.

Within the pancreas, Keratin 19 (KRT19) labels the ductal lineage and is a determinant of pancreatic ductal adenocarcinoma (PDAC). To investigate KRT19 expression dynamics, we developed a human pluripotent stem cell (PSC)-based KRT19-mCherry reporter system in different genetic backgrounds to monitor KRT19 expression from its endogenous gene locus. A differentiation protocol to generate mature pancreatic duct-like organoids was applied. While KRT19/mCherry expression became evident at the early endoderm stage, mCherry signal was present in nearly all cells at the pancreatic endoderm (PE) and pancreatic progenitor (PP) stages. Interestingly, despite homogenous KRT19 expression, mCherry positivity dropped to 50% after ductal maturation, indicating a permanent switch from biallelic to monoallelic expression. DNA methylation profiling separated the distinct differentiation intermediates, with site-specific DNA methylation patterns occurring at the KRT19 locus during ductal maturation. Accordingly, the monoallelic switch was partially reverted upon treatment with a DNA-methyltransferase inhibitor. In human PDAC cohorts, high KRT19 levels correlate with low locus methylation and decreased survival. At the same time, activation of oncogenic KRASG12D signalling in our reporter system reversed monoallelic back to biallelic KRT19 expression in pancreatic duct-like organoids. Allelic reactivation was also detected in single-cell transcriptomes of human PDACs, which further revealed a positive correlation between KRT19 and KRAS expression. Accordingly, KRAS mutant PDACs had higher KRT19 mRNA but lower KRT19 gene locus DNA methylation than wildtype counterparts. KRT19 protein was additionally detected in plasma of PDAC patients, with higher concentrations correlating with shorter progression-free survival in gemcitabine/nabPaclitaxel-treated and opposing trends in FOLFIRINOX-treated patients. Apart from being an important pancreatic ductal lineage marker, KRT19 appears tightly controlled via a switch from biallelic to monoallelic expression during ductal lineage entry and is aberrantly expressed after oncogenic KRASG12D expression, indicating a role in PDAC development and malignancy. Soluble KRT19 might serve as a relevant biomarker to stratify treatment. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Decellularized skin pretreatment by monophosphoryl lipid A and lactobacillus casei supernatant accelerate skin recellularization.

BACKGROUND: Bioscaffolds and cells are two main components in the regeneration of damaged tissues via cell therapy. Umbilical cord stem cells are among the most well-known cell types for this purpose. The main objective of the present study was to evaluate the effect of the pretreatment of the foreskin acellular matrix (FAM) by monophosphoryl lipid A (MPLA) and Lactobacillus casei supernatant (LCS) on the attraction of human umbilical cord mesenchymal stem cells (hucMSC). METHODS AND RESULTS: The expression of certain cell migration genes was studied using qRT-PCR. In addition to cell migration, transdifferentiation of these cells to the epidermal-like cells was evaluated via immunohistochemistry (IHC) and immunocytochemistry (ICC) of cytokeratin 19 (CK19). The hucMSC showed more tissue tropism in the presence of MPLA and LCS pretreated FAM compared to the untreated control group. We confirmed this result by scanning electron microscopy (SEM) analysis, glycosaminoglycan (GAG), collagen, and DNA content. Furthermore, IHC and ICC data demonstrated that both treatments increase the protein expression level of CK19. CONCLUSION: Pretreatment of acellular bioscaffolds by MPLA or LCS can increase the migration rate of cells and also transdifferentiation of hucMSC to epidermal-like cells without growth factors. This strategy suggests a new approach in regenerative medicine.

Simultaneous Detection of Collagen I Alpha II and Cytokeratin 19 mRNA by Multiplex qPCR in Liquid Biopsy in Diagnosis of Patients with Resectable Solid Tumors.

The early detection of tumors is one of the key factors in increasing overall survival in cancer patients. A wide range of cancers still do not have a system of early diagnosis; therefore, the development of new non-invasive tools in this line is essential. Accordingly, the objective of our work was to develop a non-invasive screening method for the early detection of various carcinomas in plasma using a panel that combines two markers using RT-qPCR. A retrospective case-control study was conducted to develop a cancer screening test based on the detection of stromal and epithelial biomarkers (COL1A2 and KRT19) in plasma. The expression of biomarkers was evaluated using multiplex quantitative PCR applied to 47 cases with non-metastatic tumors and 13 control participants. For both biomarkers, a cut-off value was stablished using Youden's J index through ROC curve analysis and areas under the curve (AUC) were calculated. The plasma mRNA expression level of both biomarkers was significantly higher in diseased versus healthy patients. Moreover, ROC curve analysis showed an AUC value of 0.897 for the combined model. This model also resulted in a cutoff value of 0.664, as well as a sensitivity of 83% and a specificity of 84.6%. These results suggest that the plasma expression levels of COL1A2 and KRT19 could a have potential role in detecting various types of cancer at the early stages. The combined analysis of both stromal and epithelial biomarkers would provide a non-invasive screening method that would allow us to differentiate patients with an active neoplastic process.

Atoh1+ secretory progenitors possess renewal capacity independent of Lgr5+ cells during colonic regeneration.

During homeostasis, the colonic epithelium is replenished every 3-5 days by rapidly cycling Lgr5+ stem cells. However, various insults can lead to depletion of Lgr5+ stem cells, and colonic epithelium can be regenerated from Lgr5-negative cells. While studies in the small intestine have addressed the lineage identity of the Lgr5-negative regenerative cell population, in the colon this question has remained unanswered. Here, we set out to identify which cell(s) contribute to colonic regeneration by performing genetic fate-mapping studies of progenitor populations in mice. First, using keratin-19 (Krt19) to mark a heterogeneous population of cells, we found that Lgr5-negative cells can regenerate colonic crypts and give rise to Lgr5+ stem cells. Notch1+ absorptive progenitor cells did not contribute to epithelial repair after injury, whereas Atoh1+ secretory progenitors did contribute to this process. Additionally, while colonic Atoh1+ cells contributed minimally to other lineages during homeostasis, they displayed plasticity and contributed to epithelial repair during injury, independent of Lgr5+ cells. Our findings suggest that promotion of secretory progenitor plasticity could enable gut healing in colitis.

Prognostic value of CYFRA 21 - 1 and Ki67 in advanced NSCLC patients with wild-type EGFR.

BACKGROUND: The prognostic value of cytokeratin 19 fragment (CYFRA 21 - 1) and Ki67 in advanced non-small cell lung cancer (NSCLC) patients with wild-type epidermal growth factor receptor (EGFR) remains to be explored. METHODS: In this study, 983 primary NSCLC patients from January 2016 to December 2019 were retrospectively reviewed. Finally, 117 advanced NSCLC patients with wild-type EGFR and 37 patients with EGFR mutation were included and prognostic value of CYFRA 21 - 1 and Ki67 were also identified. RESULTS: The patients age, smoking history and the Eastern Corporative Oncology Group (ECOG) performance scores were significantly different between CYFRA21-1 positive and negative groups (p < 0.05), while no significant differences were found in Ki67 high and low groups. The results of over survival (OS) demonstrated that patients with CYFRA21-1 positive had markedly shorter survival time than CYFRA21-1 negative (p < 0.001, For whole cohorts; p = 0.002, For wild-type EGFR). Besides, patients with wild-type EGFR also had shorter survival times than Ki67 high group. Moreover, In CYFRA 21 - 1 positive group, patients with Ki67 high had obviously shorter survival time compared to patients with Ki67 low (median: 24vs23.5 months; p = 0.048). However, Ki67 could not be used as an adverse risk factor for patients with EGFR mutation. Multivariate cox analysis showed that age (HR, 1.031; 95%CI, 1.003 ~ 1.006; p = 0.028), Histopathology (HR, 1.760; 95%CI,1.152 ~ 2.690; p = 0.009), CYFRA 21 - 1 (HR, 2.304; 95%CI,1.224 ~ 4.335; p = 0.01) and Ki67 (HR, 2.130; 95%CI,1.242 ~ 3.652; p = 0.006) served as independent prognostic risk factor for advanced NSCLC patients. CONCLUSIONS: Our finding indicated that CYFRA 21 - 1 was an independent prognostic factor for advanced NSCLC patients and Ki67 status could be a risk stratification marker for CYFRA 21 - 1 positive NSCLC patients with wild-type EGFR.

Evaluation of the one-step nucleic acid amplification assay for detecting lymph node metastasis in patients with cervical and endometrial cancer: A multicenter prospective study.

OBJECTIVE: This multicenter study aimed to evaluate the accuracy of the one-step nucleic acid amplification (OSNA) assay in diagnosing lymph node metastasis (LNM) in patients with cervical and endometrial cancers. METHODS: Surgically removed LNs from patients with cervical and endometrial cancer were sectioned at 2-mm intervals along the short axis direction and alternately examined using the OSNA assay and conventional histopathological examination. Ultrastaging (200-µm LN sections) was performed for metastatic LNs using hematoxylin and eosin staining and immunostaining with an anti-CK19 antibody in cases where the OSNA assay and histopathological examination (performed using 2-mm LN sections) results showed discordance. RESULTS: A total of 437 LNs from 133 patients were included; 61 patients (14%) showed metastasis by histopathological examination, with a concordance rate of 0.979 (95% confidence interval [CI]: 0.961-0.991) with the OSNA assay. The sensitivity and specificity of the OSNA assay were 0.918 (95% CI: 0.819-0.973) and 0.989 (95% CI: 0.973-0.997), respectively. Discordance between the two methods was observed in nine LNs (2.1%), and allocation bias of metastatic foci was identified as the major cause of discordance. CONCLUSIONS: The OSNA assay showed equally accurate detection of LN metastasis as the histopathological examination. We suggest that the OSNA assay may be a useful tool for the rapid intraoperative diagnosis of LN metastasis in patients with cervical and endometrial cancers.

Dysregulation of KRT19, TIMP1, and CLDN1 gene expression is associated with thyroid cancer.

Thyroid nodules are the main indicators of thyroid cancer, their malignancy is evaluated by cytological analysis and imaging technology, however, there are still cases where the result is not enough to classify thyroid cancer. Therefore, there is a necessity for accurate molecular biomarkers to collaborate in the diagnosis. Here, we analyzed the mRNA relative expression of CLDN1, TIMP1, and KRT19 genes in FNA of malignant (n = 48) and benign (n = 49) thyroid nodules by RT-qPCR analysis to assess their predictive value as cancer biomarkers. We identified a significant overexpression of the three transcripts in malignant nodules, therefore, the evaluation of their predictive capacity to distinguish between benign and malignant nodule as individual biomarkers were evaluated by logistic regression tests, obtaining promising prediction results to rule out cancer; later by random forest to create a stronger model, we included expression results with clinicopathological characteristics, the best model consists of the three-mRNA level expression with patient's history of cancer (AUC = 0.821, accuracy = 85.4% and sensitivity of 81.1%). These results demonstrate a dysregulated expression of CLDN1, KRT19 and TIMP1 in thyroid cancer, thus, represent a promising panel of biomarkers to be evaluated in indeterminate thyroid nodules.

Diagnostic of Cytokeratin-19 Gene Expression in Iranian Breast Cancer Patients.

Sentinel lymph node (SLN) biopsy is currently the recommended procedure for axillary staging in clinically node-negative early breast cancer at diagnosis. The present study aimed to identify Cytokeratin-19 (CK19) gene profiles that accurately predicted the outcome of breast cancer patients. Fifty tumor samples from breast cancer patients were analyzed for the expression of the CK19 gene using quantitative PCR. Also, normal breast tissues (N = 50) were taken from the same patients that had undergone partial or total mastectomy. This gene signature was confirmed based on tumor's stage, grade, and estrogen receptor (ER) status, using conditional logistic regression. Based on these findings, the negative reported lymph nodes for metastasis had micrometastasis in significant values. There was a significant difference between normal and cancer samples in  CK19 expression. In this sentinel node evaluation, the relationship of this gene with tumor characteristics needs to be established and discussed finding a clear role for this gene in tumor outcome.

Evaluation of CK19 and VEGF gene expression, ki67 antigen, p53 protein, C-erb-B2, and their relationship in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is one of the ten most common malignant tumors globally. This study aimed to evaluate the expression changes of Cytokeratin 19 (CK19), vascular endothelial growth factor (VEGF), P53, ki67, and c-ert-B2 in OSCC patients. For this purpose, 30 patients were selected as the case group and 30 healthy individuals as the control group. The expression of CK19 and VEGF genes in their blood serum was measured. Also, the expression of ki67, P53, and c-ert-B2 markers in squamous cell carcinoma was evaluated using immunohistochemistry. T-test was used to analyze the data. The results showed that the presence of CK19 marker in people with OSCC was positive in 17 out of 30 patients and VEGF marker in 23 out of 30 patients. The mean of ki67 positive, P53 positive, and Cerb-B2 positive cells were 399.4, 221.4, and 26.8, respectively. The correlation test between the indices showed a statistical correlation between the incidence of ki67 and P53 (r = 91.5% and p = 0.02). While statistical correlation was not seen between the incidence of ki67 and Cerb-B2 index (r = -1.7% and p = 0.97) and P53 and C-erb-B2 index (r = -13% and p = 0.8) (p <0.05). In general, the expression of VEGF and CK19 genes is higher in patients with OSCC than in healthy individuals. Therefore, examining the expression level of these two biomarkers in the blood of OSCC patients can be considered as a diagnostic screening method in the early stages of the disease. The immunohistochemical study of squamous cell carcinoma can also be used as a diagnostic screening test in the early stages of the disease.

A preliminary study on the detection of lymph node metastasis in cervical cancer using a quantitative RT-PCR assay.

OBJECTIVE: This preliminary study aimed to assess the detection accuracy of sentinel lymph node metastasis in cervical cancer using quantitative reverse transcriptase-polymerase chain reaction. METHODS: We collected cervical cancer tissues and 70 pelvic lymph node samples from patients with cervical cancer. The quantitative reverse transcriptase-polymerase chain reaction assay was performed to investigate the expression of cytokeratin 19 mRNA in cervical cancer tissues and determine the cutoff value of cytokeratin 19 mRNA between the non-metastatic and metastatic lymph nodes. RESULTS: The expression of cytokeratin 19 mRNA in cancer tissues was detected in all (71/71) the tumours, with a median copy number of 7.56 × 105/µl of RNA by quantitative reverse transcriptase-polymerase chain reaction. Sixteen lymph nodes were diagnosed as positive by pathological examination. The median copy numbers of cytokeratin 19 mRNA for positive and negative lymph nodes were 43.3 × 104/µl and 121.1/µl, respectively. The expression of cytokeratin 19 mRNA in pathologically positive lymph nodes was higher than that in the negative lymph nodes (P < 0.0001) by quantitative reverse transcriptase-polymerase chain reaction analysis. Using a receiver operating characteristic plot, the maximum sensitivity (100%) and specificity (94.4%) were obtained when the cutoff value was set at 1169 copies/µl. CONCLUSIONS: After setting the cutoff value at 1169 copies/µl, a quantitative reverse transcriptase-polymerase chain reaction assay using cytokeratin 19 mRNA showed high accuracy in detecting lymph node metastasis in cervical cancer. We believe that the quantitative reverse transcriptase-polymerase chain reaction assay using cytokeratin 19 mRNA may be acceptable for lymph node metastasis detection in patients with cervical cancer.

Feasibility of Pooled One-Step Nucleic Acid Amplification for Molecular Staging of Pathologically Node-Negative Colon Cancer: A Prospective Multicenter Study.

BACKGROUND: Although conventional one-step nucleic acid amplification (OSNA) is a useful molecular-staging method, its complexity hinders its use in clinical practice. A pooled approach for OSNA (pOSNA) has been evaluated for its feasibility in pathologically node-negative colon cancer (pNNCC) for molecular staging of lymph node metastasis in clinical practice. METHODS: Subjects were patients diagnosed with clinical stage II-IIIA colon cancer between January 2017 and September 2018. pOSNA involved harvesting pericolic lymph nodes from fresh surgical specimens, cutting them in half, placing 50% of the nodes in a single test tube, and performing the OSNA assay. The remaining halved pericolic, intermediate, and main lymph nodes were submitted for histopathologic examination, with metastasis determined by hematoxylin and eosin staining of a cut surface of each node. RESULTS: Of the 98 enrolled patients, 92 formed the analysis set. The mean number of harvested lymph nodes per case was 24.3 (range 5-66) and the mean number of lymph nodes used for pOSNA analysis was 6.9 (range 1-35). The concordance rate, sensitivity, and specificity between methods were 89.1%, 84.6% (95% confidence interval [CI] 0.80-0.91), and 90.9% (95% CI 0.88-0.94), respectively. The pOSNA upstaging rate for node-negative patients was 9.1% (6/66), and pOSNA returned false-negative results in 15.4% of node-positive cases (4/26). CONCLUSIONS: pOSNA demonstrated an upstaging rate for pNNCC equivalent to that in previous studies, suggesting its feasibility for molecular staging of pNNCC in clinical practice.

Downregulation of MMP-9 Enhances the Anti-Migratory Effect of Cyclophosphamide in MDA-MB-231 and MCF-7 Breast Cancer Cell Lines.

Metastasis is one of the most urgent issues in breast cancer patients. One of the factors necessary in the migration process is the remodeling of the extracellular matrix (ECM). Metalloproteinases (MMPs) can break down the elements of the ECM, which facilitates cell movement. Many highly aggressive tumors are characterized by high levels of MMPs. In the case of breast cancer, the association between MMP-9 and the migration potential and invasiveness of cells has been demonstrated. In addition, reports indicating increased migration of breast cancer cells after the administration of the commonly used cytostatic cyclophosphamide (CP) are particularly disturbing. Hence, our research aimed to assess the effect of CP treatment on MDA-MB-231 and MCF-7 cells and how this response is influenced by the downregulation of the MMP-9 level. The obtained results suggest that CP causes a decrease in the survival of breast cancer cells of various invasiveness, and the downregulation of MMP-9 enhances this effect, mainly by inducing apoptosis. Moreover, in the group of MMP-9 siRNA-transfected CP-treated cells, a more severe reduction in invasion and migration of cells of both lines was observed, as indicated by the migration and invasion transwell assays and Wound healing assay. Hence, we suggest that CP alone may not result in satisfactory therapeutic effects. On the other hand, the use of combination therapy targeting MMP-9, together with the CP, could improve the effectiveness of the treatment. Additionally, we confirmed a relationship between the levels of MMP-9 and cytokeratin 19 (CK19).

A Hyaluronan and Platelet-Rich Plasma Hydrogel for Mesenchymal Stem Cell Delivery in the Intervertebral Disc: An Organ Culture Study.

The purpose of the present pilot study was to evaluate the effect of a hydrogel composed of hyaluronic acid (HA) and platelet-rich plasma (PRP) as a carrier for human mesenchymal stem cells (hMSCs) for intervertebral disc (IVD) regeneration using a disc organ culture model. HA was mixed with batroxobin (BTX) and PRP to form a hydrogel encapsulating 1 × 106 or 2 × 106 hMSCs. Bovine IVDs were nucleotomized and filled with hMSCs suspended in ~200 µL of the PRP/HA/BTX hydrogel. IVDs collected at day 0 and nucleotomized IVDs with no hMSCs and/or hydrogel alone were used as controls. hMSCs encapsulated in the hydrogel were also cultured in well plates to evaluate the effect of the IVD environment on hMSCs. After 1 week, tissue structure, scaffold integration, hMSC viability and gene expression of matrix and nucleus pulposus (NP) cell markers were assessed. Histological analysis showed a better preservation of the viability of the IVD tissue adjacent to the gel in the presence of hMSCs (~70%) compared to the hydrogel without hMSCs. Furthermore, disc morphology was maintained, and the hydrogel showed signs of integration with the surrounding tissues. At the gene expression level, the hydrogel loaded with hMSCs preserved the normal metabolism of the tissue. The IVD environment promoted hMSC differentiation towards a NP cell phenotype by increasing cytokeratin-19 (KRT19) gene expression. This study demonstrated that the hydrogel composed of HA/PRP/BTX represents a valid carrier for hMSCs being able to maintain a good cell viability while stimulating cell activity and NP marker expression.

A rare case of high-grade intraductal carcinoma of the upper lip: immunohistochemical and genetic analyses.

Although intraductal carcinoma (IDC) of the salivary glands was previously called low-grade cribriform cystadenocarcinoma, it was newly categorized in the 4th version of the World Health Organization classification. We report a case of IDC of the upper lip and examined it immunohistochemically and genetically. The patient was a 48-year-old Japanese female, who noticed a tiny nodule on her left upper lip. Histologically, the tumor cells, which had eosinophilic cytoplasm, exhibited papillary and solid growth patterns, and regions of suspected microinvasion or intraductal spread were also seen at the periphery of the tumor. Small necrotic foci were noted. Immunohistochemically, the tumor cells were diffusely positive for the androgen receptor, CK19, CK5/6, EGFR, and SOX10, whereas they were focally positive for GCDFP-15, S-100 protein, and mammaglobin. The tumor nests were surrounded by alpha-smooth muscle actin-p63-/calponin-/CK14-positive myoepithelial cells. The Ki-67 labeling index was 51.2%. Genetic analysis showed no evidence of the TRIM27-RET or NCOA4-RET fusion gene. We finally diagnosed the tumor as a high-grade mixed intercalated duct/apocrine-type IDC of the upper lip. IDC of the minor salivary glands is exceedingly rare. We discuss diagnostic problems associated with minor salivary gland lesions, and the "basal-like" phenotype of this case.

Plasma extracellular vesicle long RNA profiling identifies a diagnostic signature for the detection of pancreatic ductal adenocarcinoma.

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDAC) is difficult to diagnose at resectable stage. Recent studies have suggested that extracellular vesicles (EVs) contain long RNAs. The aim of this study was to develop a diagnostic (d-)signature for the detection of PDAC based on EV long RNA (exLR) profiling. DESIGN: We conducted a case-control study with 501 participants, including 284 patients with PDAC, 100 patients with chronic pancreatitis (CP) and 117 healthy subjects. The exLR profile of plasma samples was analysed by exLR sequencing. The d-signature was identified using a support vector machine algorithm and a training cohort (n=188) and was validated using an internal validation cohort (n=135) and an external validation cohort (n=178). RESULTS: We developed a d-signature that comprised eight exLRs, including FGA, KRT19, HIST1H2BK, ITIH2, MARCH2, CLDN1, MAL2 and TIMP1, for PDAC detection. The d-signature showed high accuracy, with an area under the receiver operating characteristic curve (AUC) of 0.960, 0.950 and 0.936 in the training, internal validation and external validation cohort, respectively. The d-signature was able to identify resectable stage I/II cancer with an AUC of 0.949 in the combined three cohorts. In addition, the d-signature showed superior performance to carbohydrate antigen 19-9 in distinguishing PDAC from CP (AUC 0.931 vs 0.873, p=0.028). CONCLUSION: This study is the first to characterise the plasma exLR profile in PDAC and to report an exLR signature for the detection of pancreatic cancer. This signature may improve the prognosis of patients who would have otherwise missed the curative treatment window.

Keratin 18 is an integral part of the intermediate filament network in murine skeletal muscle.

Intermediate filaments (IFs) contribute to force transmission, cellular integrity, and signaling in skeletal muscle. We previously identified keratin 19 (Krt19) as a muscle IF protein. We now report the presence of a second type I muscle keratin, Krt18. Krt18 mRNA levels are about half those for Krt19 and only 1:1,000th those for desmin; the protein was nevertheless detectable in immunoblots. Muscle function, measured by maximal isometric force in vivo, was moderately compromised in Krt18-knockout (Krt18-KO) or dominant-negative mutant mice (Krt18 DN), but structure was unaltered. Exogenous Krt18, introduced by electroporation, was localized in a reticulum around the contractile apparatus in wild-type muscle and to a lesser extent in muscle lacking Krt19 or desmin or both proteins. Exogenous Krt19, which was either reticular or aggregated in controls, became reticular more frequently in Krt19-null than in Krt18-null, desmin-null, or double-null muscles. Desmin was assembled into the reticulum normally in all genotypes. Notably, all three IF proteins appeared in overlapping reticular structures. We assessed the effect of Krt18 on susceptibility to injury in vivo by electroporating siRNA into tibialis anterior (TA) muscles of control and Krt19-KO mice and testing 2 wk later. Results showed a 33% strength deficit (reduction in maximal torque after injury) compared with siRNA-treated controls. Conversely, electroporation of siRNA to Krt19 into Krt18-null TA yielded a strength deficit of 18% after injury compared with controls. Our results suggest that Krt18 plays a complementary role to Krt19 in skeletal muscle in both assembling keratin-based filaments and transducing contractile force.

Characterization of Krt19 CreERT allele for targeting the nucleus pulposus cells in the postnatal mouse intervertebral disc.

Intervertebral disc degeneration and associated back pain are relatively common but sparsely understood conditions, affecting over 70% of the population during some point of life. Disc degeneration is often associated with a loss of nucleus pulposus (NP) cells. Genetic mouse models offer convenient avenues to understand the cellular and molecular regulation of the disc during its formation, growth, maintenance, and aging. However, due to the lack of inducible driver lines to precisely target NP cells in the postnatal mouse disc, progress in this area of research has been moderate. NP cells are known to express cytokeratin 19 (Krt19), and tamoxifen (Tam)-inducible Krt19CreERT allele is available. The current study describes the characterization of Krt19CreERT allele to specifically and efficiently target NP cells in neonatal, skeletally mature, middle-aged, and aged mice using two independent fluorescent reporter lines. The efficiency of recombination at all ages was validated by immunostaining for KRT19. Results show that following Tam induction, Krt19CreERT specifically drives recombination of NP cells in the spine of neonatal and aged mice, while no recombination was detected in the surrounding tissues. Knee joints from skeletally mature Tam-treated Krt19CreERT/+ ; R26tdTOM mouse show the absence of recombination in all tissues and cells of the knee joint. Thus, this study provides evidence for the use of Krt19CreERT allele for genetic characterization of NP cells at different stages of the mouse life.

Single-cell RNA sequencing reveals the regenerative potential of thyroid follicular epithelial cells in metastatic thyroid carcinoma.

Thyroid stimulating hormone deficiency is the cornerstone of treatment for metastatic thyroid cancer. Due to the loss of follicular epithelial cells in thyroid cancer, the thyroid gland degenerates to 85% of its original size. When thyroid stimulating hormone is restored, follicular epithelial cells in thyroid cancer regenerate, which is postulated to be related to stem-like cells. By single cell RNA seq, we found a group of rare thyroid follicular epithelial cells in mouse metastatic thyroid cancer, which expressed stem-like genes (CD44V6+ and CD133+) and a large number of differentiated cells (CD44V6+ and CD24+). In mouse and in organoids, the two subsets contribute equally to metastatic thyroid cancer regeneration. The analysis of human metastatic thyroid cancer revealed that the differentiated thyroid follicular epithelial cell subpopulation was similar to that of the stem like epithelial cell subpopulation, and the regeneration potential was also enhanced after thyroid stimulating hormone ablation. Accordingly, we propose that the regeneration of metastatic thyroid cancer is driven by almost all persistent thyroid follicular epithelial cells, not only by few stem-like cells.

Intranasal delivery of cationic liposome-protamine complex mRNA vaccine elicits effective anti-tumor immunity.

Immunization with synthetic mRNA encoding tumor-associated antigens is an emerging vaccine strategy for the treatment of cancer. In order to prevent mRNA degradation, promote antigen-presenting cells antigen presentation, and induce an anti-tumor immune response, we investigated the nasal administration of mRNA vaccines with positively charged protamine to concentrate mRNA, form a stable polycation-mRNA complex, and encapsulate the complex with DOTAP/Chol/DSPE-PEG cationic liposomes. Cationic liposome/protamine complex (LPC) showed significantly greater efficiency in uptake of vaccine particles in vitro and stronger capacities to stimulate dendritic cell maturation, which further induced a potent anti-tumor immune response. Intranasal immunization of mice with cationic LPC containing mRNA encoding cytokeratin 19 provoked a strong cellular immune response and slowed tumor growth in an aggressive Lewis lung cancer model. The results of this study provide evidence that cationic LPC can be used as a safe and effective adjuvant and this mRNA formulation provides a basis for anti-cancer vaccination of humans.