Gigaxonin is an E3 ubiquitin ligase that plays a role in cytoskeletal stability. Its role in cancer is not yet clearly understood. Our previous studies of head and neck cancer had identified ...gigaxonin interacting with p16 for NFκB ubiquitination. To explore its role in cancer cell growth suppression, we analyzed normal and tumor DNA from cervical and head and neck cancers. There was a higher frequency of exon 8 SNP (c.1293 C>T, rs2608555) in the tumor (46% vs. 25% normal, P = 0.011) pointing to a relationship to cancer. Comparison of primary tumor with recurrence and metastasis did not reveal a statistical significance. Two cervical cancer cell lines, ME180 and HT3 harboring exon 8 SNP and showing T allele expression correlated with higher gigaxonin expression, reduced in vitro cell growth and enhanced cisplatin sensitivity in comparison with C allele expressing cancer cell lines. Loss of gigaxonin expression in ME180 cells through CRISPR-Cas9 or siRNA led to aggressive cancer cell growth including increased migration and Matrigel invasion. The in vitro cell growth phenotypes were reversed with re-expression of gigaxonin. Suppression of cell growth correlated with reduced Snail and increased e-cadherin expression. Mouse tail vein injection studies showed increased lung metastasis of cells with low gigaxonin expression and reduced metastasis with reexpression of gigaxonin. We have found an association between C allele expression and RNA instability and absence of multimeric protein formation. From our results, we conclude that gigaxonin expression is associated with suppression of epithelial-mesenchymal transition through inhibition of Snail.
Our results suggest that GAN gene exon 8 SNP T allele expression correlates with higher gigaxonin expression and suppression of aggressive cancer cell growth. There is downregulation of Snail and upregulation of e-cadherin through NFκB ubiquitination. We hypothesize that exon 8 T allele and gigaxonin expression could serve as diagnostic markers of suppression of aggressive growth of head and neck cancer.
Blocking programmed death protein 1 (PD-1) negative immune receptor has produced remarkable progress in treating patients with advanced cancers, such as melanoma, lung, head and neck, kidney, ...bladder, Hodgkin’s disease, mismatch repair deficient colon cancer, liver and ovarian cancer with high mutational burden, etc. However, only subset of patients are benefitting from this therapy and substantial portion of patients have relapsed after long durable response. Therefore, it is critical to understand its resistance mechanisms to improve therapeutic efficacy and select right patients for checkpoint blockade immunotherapy. We have identified mutations associated with acquired resistance among 4 patients with advanced melanoma, including JAK1/2 that resulted in loss of adaptive programmed death protein ligand 1 (PD-L1). We reasoned that this could occur among patients with primary resistance. JAK1/2 inactivating mutations were found in tumor biopsies of 1 of 23 patients with melanoma and in 1 of 16 patients with mismatch repair deficient colon cancer treated with PD-1 blockade. Two out of 48 human melanoma cell lines had JAK1/2 mutations led to loss of PD-L1 expression upon interferon gamma exposure mediated by disabled interferon gamma receptor signaling pathway. JAK1/2 loss-of-function alterations in TCGA confer adverse outcomes in patients. sh-RNA screening and chromatin immunoprecipitation approach on interferon signaling genes for selected melanoma cell lines revealed JAK1/2, STAT1/2/3 and IRF-1 are the key molecules involved in PD-L1 expression. RNA-seq analyses for tumors enriched with these genes were associated with clinical response to PD-1 blockade. Therefore, we propose that JAK1/2 loss-of-function mutations are a genetic mechanism of lack of reactive PD-L1 expression and response to interferon gamma, leading to primary or acquired resistance to PD-1 blockade therapy.
We have observed overexpression of PACS-1, a cytosolic sorting protein in primary cervical tumors. Absence of exonic mutations and overexpression at the RNA level suggested a transcriptional and/or ...posttranscriptional regulation. University of California Santa Cruz genome browser analysis of PACS-1 micro RNAs (miR), revealed two 8-base target sequences at the 3' terminus for hsa-miR-34a and hsa-miR-449a. Quantitative RT-PCR and Northern blotting studies showed reduced or loss of expression of the two microRNAs in cervical cancer cell lines and primary tumors, indicating dysregulation of these two microRNAs in cervical cancer. Loss of PACS-1 with siRNA or exogenous expression of hsa-miR-34a or hsa-miR-449a in HeLa and SiHa cervical cancer cell lines resulted in DNA damage response, S-phase cell cycle arrest, and reduction in cell growth. Furthermore, the siRNA studies showed that loss of PACS-1 expression was accompanied by increased nuclear γH2AX expression, Lys
-p53 acetylation, and genomic instability. PACS-1 re-expression through LNA-hsa-anti-miR-34a or -449a or through PACS-1 cDNA transfection led to the reversal of DNA damage response and restoration of cell growth. Release of cells post 24-h serum starvation showed PACS-1 nuclear localization at G
-S phase of the cell cycle. Our results therefore indicate that the loss of hsa-miR-34a and hsa-miR-449a expression in cervical cancer leads to overexpression of PACS-1 and suppression of DNA damage response, resulting in the development of chemo-resistant tumors.
A 30-year-old woman presented to an outside hospital with pain in the right upper abdomen. Imaging revealed over 100 liver lesions, the largest measuring 74 mm×71 mm, and multiple lytic bone lesions. ...An outpatient liver biopsy showed a poorly differentiated adenocarcinoma favouring a breast primary. The tumour was oestrogen and progesterone receptor negative, but human epidermal growth factor 2 (HER2/neu) amplified. In her second clinic visit she had decompensated liver failure manifested by new-onset ascites and jaundice. Initially, the chemotherapy plan was for docetaxel, pertuzumab and trastuzumab, but given her severe liver dysfunction we used a combination of carboplatin, pertuzumab and trastuzumab as an inpatient. She was hospitalised for 14 days and eventually discharged with a marked improvement of her symptoms and liver tests. She subsequently completed five outpatient chemotherapy cycles. We showed that carboplatin is a possible alternative to docetaxel when severe liver dysfunction precludes docetaxel's use in combination with pertuzumab and trastuzumab.
Tumor responses to PD-1 blockade therapy are mediated by T cells, which we characterized in 102 tumor biopsies obtained from 53 patients treated with pembrolizumab, an antibody to PD-1. Biopsies were ...dissociated and single cell infiltrates were analyzed by multicolor flow cytometry using two computational approaches to resolve the leukocyte phenotypes at the single cell level. There was a statistically significant increase in the frequency of T cells in patients who responded to therapy. The frequency of intratumoral B cells and monocytic myeloid-derived suppressor cells (moMDSCs) significantly increased in patients’ biopsies taken on treatment. The percentage of cells with a T regulatory phenotype, monocytes, and NK cells did not change while on PD-1 blockade therapy. CD8
+
T memory cells were the most prominent phenotype that expanded intratumorally on therapy. However, the frequency of CD4
+
T effector memory cells significantly decreased on treatment, whereas CD4
+
T effector cells significantly increased in nonresponding tumors on therapy. In peripheral blood, an unusual population of blood cells expressing CD56 were detected in two patients with regressing melanoma. In conclusion, PD-1 blockade increases the frequency of T cells, B cells, and MDSCs in tumors, with the CD8
+
T effector memory subset being the major T-cell phenotype expanded in patients with a response to therapy.
A 30-year-old woman presented to an outside hospital with pain in the right upper abdomen. Imaging revealed over 100 liver lesions, the largest measuring 74 mm×71 mm, and multiple lytic bone lesions. ...An outpatient liver biopsy showed a poorly differentiated adenocarcinoma favouring a breast primary. The tumour was oestrogen and progesterone receptor negative, but human epidermal growth factor 2 (HER2/neu) amplified. In her second clinic visit she had decompensated liver failure manifested by new-onset ascites and jaundice. Initially, the chemotherapy plan was for docetaxel, pertuzumab and trastuzumab, but given her severe liver dysfunction we used a combination of carboplatin, pertuzumab and trastuzumab as an inpatient. She was hospitalised for 14 days and eventually discharged with a marked improvement of her symptoms and liver tests. She subsequently completed five outpatient chemotherapy cycles. We showed that carboplatin is a possible alternative to docetaxel when severe liver dysfunction precludes docetaxel's use in combination with pertuzumab and trastuzumab.
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