GADD34 suppresses wound healing by upregulating expression of myosin IIA

Collective cell migration relies on PPP1R15-mediated regulation of the endoplasmic reticulum stress response

Collective cell migration is integral to many developmental and disease processes. Previously, we discovered that protein phosphatase 1 (Pp1) promotes border cell collective migration in the Drosophila ovary. We now report that the Pp1 phosphatase regulatory subunit dPPP1R15 is a critical regulator of border cell migration. dPPP1R15 is an ortholog of mammalian PPP1R15 proteins that attenuate the endoplasmic reticulum (ER) stress response. We show that, in collectively migrating border cells, dPPP1R15 phosphatase restrains an active physiological protein kinase R-like ER kinase- (PERK)-eIF2α-activating transcription factor 4 (ATF4) stress pathway. RNAi knockdown of dPPP1R15 blocks border cell delamination from the epithelium and subsequent migration, increases eIF2α phosphorylation, reduces translation, and drives expression of the stress response transcription factor ATF4. We observe similar defects upon overexpression of ATF4 or the eIF2α kinase PERK. Furthermore, we show that normal border cells express markers of the PERK-dependent ER stress response and require PERK and ATF4 for efficient migration. In many other cell types, unresolved ER stress induces initiation of apoptosis. In contrast, border cells with chronic RNAi knockdown of dPPP1R15 survive. Together, our results demonstrate that the PERK-eIF2α-ATF4 pathway, regulated by dPPP1R15 activity, counteracts the physiological ER stress that occurs during collective border cell migration. We propose that in vivo collective cell migration is intrinsically "stressful," requiring tight homeostatic control of the ER stress response for collective cell cohesion, dynamics, and movement.

DT-13 inhibits breast cancer cell migration via non-muscle myosin II-A regulation in tumor microenvironment synchronized adaptations

BACKGROUND

Tumor metastasis is a terrifying characteristic of cancer. Numerous studies have been conducted to overcome metastasis by targeting tumor microenvironment (TME). However, due to complexity of tumor microenvironment, it remained difficult for accurate targeting. Dwarf-lillytruf tuber monomer-13 (DT-13) possess good potential against TME.

OBJECTIVE

As TME is supportive for tumor metastasis, alternatively it is a challenging for therapeutic intervention. In our present study, we explored molecular mechanism through which TME induced cell migration and how DT-13 interferes in this mechanism.

METHODS

We used a novel model of co-culture system which is eventually developed in our lab. Tumor cells were co-cultured with hypoxia induced cancer-associated fibroblasts (CAF) or with chemically induced cancer-associated adipocytes (CAA). The effect of hypoxia in conditioned medium for CAF was assessed through expression of α-SMA and HIF by western blotting while oil red staining was done to assess the successful chemical induction for adipocytes (CAA), the effect of TME through conditioned medium on cell migration was analyzed by trans-well cell migration, and cell motility (wound healing) analyses. The expression changes in cellular proteins were assessed through western blotting and immunofluorescent studies.

RESULTS AND CONCLUSION

Our results showed that tumor microenvironment has a direct role in promoting breast cancer cell migration by stromal cells; moreover, we found that DT-13 restricts this TME regulated cell migration via targeting stromal cells in vitro. Additionally we also found that DT-13 targets NMII-A for its effect on breast cancer cell migration for the regulation of stromal cells in TME.

Tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia: a single-institution experience

Background

Patients with CML treated with TKI can have a life expectancy comparable to that of the general population. Due to the extended duration of TKI administration, treatment discontinuation has been increasingly sought.

Methods

Medical records of 100 patients with CML who were in MR^4.5 and discontinued their TKI outside clinical trials were reviewed.

Results

After a median follow-up of 30 months (range, 5–112 months) after discontinuation, 35% and 17% lost MR^4.5 and major molecular response (MMR), respectively. Only six patients lost MMR 12 months or more after discontinuation. Loss of MR^4.5 was observed in 29% and 7% of patients with sustained MR^4.5 duration of more than 2 and 6 years before discontinuation, respectively. By univariate analysis, there was a higher risk of loss of MR^4.5 for patients who were treated for less than 87 months, received second or subsequent line TKI, never received interferon, or those with sustained MR^4.5 for less than 6 years. By multivariate analysis, sustained MR^4.5 for 6 years or more was the only significant predictor for durable response. Overall, 30% of patients who discontinued while in MR^4.5 were retreated with 93% regaining MR^4.5 at a median of 5 months.

Conclusion

These results demonstrate that under proper conditions, treatment discontinuation is feasible outside of clinical trial setting. MR^4.5 duration of 6 years or more before discontinuation is associated with very low risk of loss of MR^4.5.

Female GADD34 mice develop age-related inflammation and hepatocellular carcinoma

AIM

To analyze the impact of sex on GADD34 function, we studied the aging of female GADD34-deficient mice and compared them with male GADD34-deficient mice.

METHODS

We used GADD34-deficient mice on a C57BL/6 background. These mice were fed a normal diet throughout their life. Alternatively, they were fed a high-fat diet at 3 months-of-age. Liver tissues taken from mice were analyzed by hematoxylin-eosin staining and immunohistochemical methods. Fresh liver cells were analyzed by flow cytometry.

RESULTS

We found that female GADD34-deficient mice did not develop obesity or fatty livers. However, female GADD34-deficient mice had infiltrations of myeloid cells in the liver, followed by liver atrophy. Many female GADD34-deficient mice developed hepatocellular carcinoma, whereas female wild-type (WT) mice did not show hepatocellular carcinoma during aging. Female GADD34-deficient mice and female WT mice developed the same percentages of lymphoma. Although a high-fat diet induced a higher level of steatosis in young male GADD34-deficient mice compared with WT mice, a high-fat diet induced the same level of steatosis in young female GADD34-deficient mice compared with WT mice. However, GADD34-deficient female young mice had a higher level of infiltration of myeloid cells and myofibroblasts than WT mice.

CONCLUSIONS

In contrast to male GADD34-deficient mice, female GADD34-deficient mice did not show obesity as they aged. However, similar to the males, they developed inflammation followed by hepatocellular carcinoma. Geriatr Gerontol Int 2017; 17: 2593-2601.