Ovarian cancer is estimated to reach 22,530 diagnoses and cause 13,980 cancer deaths per year. The most common histology diagnosed of ovarian cancer is epithelial ovarian carcinomas (EOC). An aggressive epithelial subtype is clear cell ovarian carcinoma (CCOC) and is characterized as a non-serous ovarian cancer. Protein kinase C (PKC) is an enzymatic family of proteins that have been found to be a component in cancer progression, tissue invasion, and metastasis. The atypical PKC (aPKC) isoforms, PKC-ι and PKC-ζ, have been suggested to participate in the increased proliferation of ovarian cancers. Previous studies have indicated that novel aPKC inhibitors ICA-1S and ζ-Stat decreased the migratory behaviors of colorectal cancer cells and were selective for PKC-ι/λ and PKC-ζ, respectively. The aims of this investigation were to further determine the binding mechanisms of ζ-Stat, expand on the tissue range of these compounds, investigate the therapeutic potential of ζ-Stat in CCOC, and to illustrate the disruption of invasion via the PKC-ζ signaling cascade. The methods utilized were molecular docking and virtual target screening, Western blot analysis, end-point PCR, GST pull down, cell viability and invasion and migration assays. We discovered that the small molecule inhibitor, ζ-Stat, is a prospective drug candidate to investigate as a novel potential treatment for CCOC. We also found that the PKC-ζ/Ect2/Rac1 activation pathway was decreased by ζ-Stat, which in turn decreased invasive behavior of CCOC.

Despite enormous scientific advancements in cancer treatment, there is a need for research to combat cancer, particularly bladder cancer. Drugs once proved to be effective in treating bladder cancer have shown reduced efficacy; hence, the cancer recurrence rate is increasing. To overcome this situation, several strategies have been considered, including the development of novel active drugs or modification of existing therapeutic regimens by combining two or more existing drugs. In recent years, atypical protein kinase Cs (PKCs), phospholipid-dependent serine/threonine kinases, have been considered as a central regulator of various cancer-associated signaling pathways, and they control cell cycle progression, tumorigenesis and metastasis. Additionally, the biologically crucial mTOR signaling pathway is altered in numerous types of cancer, including bladder cancer. Furthermore, despite independent activation, atypical PKC signaling can be triggered by mTOR. The present study examined whether the concurrent inhibition of atypical PKCs and mTOR using a combination of novel atypical PKC inhibitors (ICA-I, an inhibitor of PKC-ι; or ζ-Stat, an inhibitor of PKC-ζ) and rapamycin blocks bladder cancer progression. In the present study, healthy bladder MC-SV-HUCT2 and bladder cancer TCCSUP cells were tested and subjected to a WST1 assay, western blot analysis, immunoprecipitation, a scratch wound healing assay, flow cytometry and immunofluorescence analyses. The results revealed that the combination therapy induced a reduction in human bladder cancer cell viability compared with control and individual atypical PKC inhibitor and rapamycin treatment. Additionally, the concurrent inhibition of atypical PKCs and mTOR retards the migration of bladder cancer cells. These findings indicated that the administration of atypical PKC inhibitors together with rapamycin could be a useful therapeutic option in treating bladder cancer.

Purpose: The options for treating lung cancers are limited, as diagnosis typically occurs during the late stages of the disease. There is a dire need to develop aPKC (atypical Protein Kinase C) inhibitors due to aPKC overexpression and contributions to lung cancer malignancies. In this study, we investigate the role of atypical PKCs (aPKCs) in cell proliferation and migration in lung cancer cell lines and the effect of the novel aPKC inhibitor DNDA (3,4-amino-2,7 napthalene disulfonic acid). Methods: The normal and lung cancer cells were treated with various concentrations of DNDA. We used a WST assay to determine lung cell viability, then analyzed cell apoptosis through Annexin V/PI staining and flow cytometry. Immunoprecipitation determined the proteins' associations, and Western blot allowed testing of the expression of interest proteins. We also employed the UbiTest to identify the ubiquitination of the FAK. The scratch and transwell assays measured cell migration and invasion of lung cancer cells. Results: Our data from cell viability and flow cytometry showed a significant reduction in cell proliferation and induction of apoptosis with DNDA treatment in lung cancer cells, as well as no toxic effect on normal BEAS-2B lung cells. Western blot results showed that the phosphorylation of PKC-iota and phosphorylation of FAK decreased in A549 lung cancer cells upon DNDA treatment. Immunoprecipitation (IP) data revealed an association of PKC-ι with FAK and FAK with Casitas B-lineage lymphoma proto-oncogene-b (Cbl-b). UbiTest results suggest that PKC-ι regulates FAK cleavage through its ubiquitination by Cbl-b, thereby inhibiting A549 lung cancer cells' migration. This was evident from scratch, invasion, and migration assays. Conclusion: Our study data suggest that DNDA inhibits cell proliferation and induces apoptosis in lung cancer cells. Moreover, DNDA inhibit A549 lung cancer cells' migration by PKC-ι/FAK ubiquitination via Cbl-b.

Lung cancer is the second most common cancer and it is the leading cause of cancer death in both men and women. PKC isozymes play an important role in the development and progression of many cancers by regulating the cell cycle, survival, apoptosis, cell motility and malignant transformation. Our focus is to study the role of atypical PKCs (aPKC) in cell proliferation and migration in lung cancer cell lines. We used a novel non-specific inhibitor of aPKC namely DNDA (3,4-amino-2,7napthalenedisulfonic acid). Our hypothesis is that DNDA inhibits cell proliferation and migration of lung cancer cells. Our data from cell viability and flow cytometry showed significant reduction in cell proliferation and induction of apoptosis with DNDA (10µM) in A549 and H1299 lung cancer cells. Additionally, DNDA showed no toxic effect on BEAS-2B normal lung cells. Elevated levels of Focal Adhesion kinase (FAK) are implicated in the progression of cancer and plays a vital role in the invasion and migration of cancer cells. Western blot results showed that the phosphorylation of PKC-ι and phosphorylation of FAK were decreased in A549 lung cancer cells upon DNDA treatment. Moreover, there was no significant reduction in phosphorylation of FAK in H1299 lung cancer cells upon treatment with DNDA. Immunoprecipitation (IP) data revealed an association of PKC-ι with FAK and FAK with Cbl-b. Ubitest results suggests that PKC-ι regulates the cleavage of FAK through its ubiquination by cbl-b and thus inhibits the migration of A549 lung cancer cells which was evident from scratch assay. Our data indicates that DNDA might inhibit the migration of A549 lung cancer cells by PKC-ι/FAK ubiquination via Cbl-b. Citation Format: Raja Reddy Bommareddy, Rekha Patel, Mildred Acevedo Duncan. Effects of atypical protein Kinase c inhibitor (DNDA) on lung cancer proliferation and migration by PKC-ι/FAK ubiquination through the Cbl-b pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4437.

No abstract